--- /srv/rebuilderd/tmp/rebuilderdcwK4uQ/inputs/erlang-doc_27.3.4.4+dfsg-1_all.deb
+++ /srv/rebuilderd/tmp/rebuilderdcwK4uQ/out/erlang-doc_27.3.4.4+dfsg-1_all.deb
├── file list
│ @@ -1,3 +1,3 @@
│  -rw-r--r--   0        0        0        4 2025-10-31 11:57:11.000000 debian-binary
│ --rw-r--r--   0        0        0    39836 2025-10-31 11:57:11.000000 control.tar.xz
│ --rw-r--r--   0        0        0 16799524 2025-10-31 11:57:11.000000 data.tar.xz
│ +-rw-r--r--   0        0        0    39824 2025-10-31 11:57:11.000000 control.tar.xz
│ +-rw-r--r--   0        0        0 16801328 2025-10-31 11:57:11.000000 data.tar.xz
├── control.tar.xz
│ ├── control.tar
│ │ ├── ./md5sums
│ │ │ ├── ./md5sums
│ │ │ │┄ Files differ
│ │ │ ├── line order
│ │ │ │ @@ -247,15 +247,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/search_data-24AC38FF.js
│ │ │ │ +usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/search_data-DCEA5CE3.js
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/sidebar_items-0A25BDF1.js
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/driver.html
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/driver_entry.html
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/epmd_cmd.html
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_cmd.html
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_dist_protocol.html
│ │ │ │  usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_driver.html
│ │ │ │ @@ -370,15 +370,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/search_data-47E11C0C.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/search_data-7ECECF0A.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/sidebar_items-020EA270.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/event_handler_chapter.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/example_chapter.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/getting_started_chapter.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/install_chapter.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/introduction.html
│ │ │ │ @@ -516,15 +516,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/search_data-6D666814.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/search_data-0488DFD4.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/sidebar_items-F976ACE0.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/notes.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/search.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/typer_cmd.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/.build
│ │ │ │  usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/404.html
│ │ │ │ @@ -781,15 +781,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/search_data-D71AAFA6.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/search_data-FF6A1601.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/sidebar_items-B6B07F6E.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/ftp.epub
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/ftp.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/ftp_client.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/introduction.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/notes.html
│ │ │ │ @@ -1176,15 +1176,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/search_data-465DEDF7.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/search_data-D78563F6.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/sidebar_items-19ECDBA9.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/error_handling.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/getting_started.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/introduction.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/notes.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/odbc.epub
│ │ │ │ @@ -1332,15 +1332,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/search_data-A1188F1F.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/search_data-1DC1D27C.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/sidebar_items-E5CACCF4.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dtrace.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dyntrace.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/instrument.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/lttng.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/msacc.html
│ │ │ │ @@ -1500,15 +1500,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/search_data-E0401131.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/search_data-AAB6B0F2.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/sidebar_items-F32BF3C6.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/hardening.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/introduction.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/notes.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/search.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh.epub
│ │ │ │ @@ -1542,15 +1542,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/search_data-2DAE4F8E.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/search_data-31FB6662.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/sidebar_items-617A7806.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/notes.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/search.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl.epub
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl_app.html
│ │ │ │ @@ -1684,15 +1684,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/search_data-1D7BB8C0.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/search_data-B09DB05B.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/sidebar_items-2B4A1108.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/epp_dodger.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_comment_scan.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_prettypr.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_recomment.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_syntax.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_syntax_lib.html
│ │ │ │ @@ -1719,15 +1719,15 @@
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ │ -usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/search_data-7B342769.js
│ │ │ │ +usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/search_data-BA5DB564.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/sidebar_items-3CBBBF05.js
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/getting_started.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/index.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/introduction.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/notes.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/search.html
│ │ │ │  usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/tftp.epub
├── data.tar.xz
│ ├── data.tar
│ │ ├── file list
│ │ │ @@ -137,15 +137,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)      292 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/ssh.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      293 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/ssl.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      294 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/stdlib.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      300 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/syntax_tools.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     2286 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/.build
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5648 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/404.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   654589 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/Erlang System Documentation.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   654626 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/Erlang System Documentation.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    53542 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/applications.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    97489 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/appup_cookbook.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/assets/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7982 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/assets/ballpoint-pen.svg
│ │ │  -rw-r--r--   0 root         (0) root         (0)     2284 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/assets/dist1.gif
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5214 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/assets/dist2.gif
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5007 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/doc/system/assets/dist3.gif
│ │ │ @@ -304,15 +304,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)  2379224 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/search_data-24AC38FF.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)  2379224 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/search_data-DCEA5CE3.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    99983 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/dist/sidebar_items-0A25BDF1.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    67771 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/driver.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    34520 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/driver_entry.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    20642 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/epmd_cmd.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   124695 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_cmd.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    94002 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_dist_protocol.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   159610 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_driver.html
│ │ │ @@ -351,15 +351,15 @@
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1060 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/.build
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6010 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/404.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6692 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/api-reference.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)    96847 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/asn1.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    96858 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/asn1.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   140490 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/asn1_getting_started.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9328 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/asn1_introduction.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7454 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/asn1_overview.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    78800 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/asn1_spec.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    35477 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/asn1ct.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/assets/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1340 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/asn1-5.3.4.2/doc/html/assets/exclusive_Win_But.gif
│ │ │ @@ -397,15 +397,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    10672 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/api-reference.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/assets/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     4963 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/assets/config.gif
│ │ │  -rw-r--r--   0 root         (0) root         (0)    10726 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/assets/html_logs.gif
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5837 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/assets/logo.png
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9561 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/assets/tc_execution.gif
│ │ │  -rw-r--r--   0 root         (0) root         (0)    21795 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/basics_chapter.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   399364 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/common_test.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   399362 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/common_test.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7502 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/common_test_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    59626 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/config_file_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    25541 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/cover_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   182818 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/ct.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12310 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/ct_cover.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    30032 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/ct_ftp.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    77362 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/ct_hooks.html
│ │ │ @@ -438,15 +438,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)   585051 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/search_data-47E11C0C.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   585051 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/search_data-7ECECF0A.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    58564 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/dist/sidebar_items-020EA270.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    31486 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/event_handler_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    62593 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/example_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    26740 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/getting_started_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      270 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     8025 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/install_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     8890 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/common_test-1.27.7/doc/html/introduction.html
│ │ │ @@ -466,15 +466,15 @@
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/assets/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5837 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/assets/logo.png
│ │ │  -rw-r--r--   0 root         (0) root         (0)    24226 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/beam_ssa.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   450809 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/cerl.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    28701 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/cerl_clauses.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    28995 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/cerl_trees.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    84370 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/compile.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   181852 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/compiler.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   181857 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/compiler.epub
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/dist/
│ │ │  -rw-r--r--   0 root         (0) root         (0)    20933 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/dist/handlebars.runtime-CFQAK6SD.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    33580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/dist/handlebars.templates-K7URE6B4.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    70589 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/dist/html-55NP3CS6.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    67213 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/dist/html-erlang-WGRVP7UZ.css
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17732 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/dist/inconsolata-latin-400-normal-OXLHDACS.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17976 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/compiler-8.6.1.2/doc/html/dist/inconsolata-latin-700-normal-S55P5GAG.woff2
│ │ │ @@ -500,15 +500,15 @@
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)      992 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/.build
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6016 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/404.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    35139 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/algorithm_details.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6670 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/api-reference.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/assets/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5837 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/assets/logo.png
│ │ │ --rw-r--r--   0 root         (0) root         (0)   127050 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/crypto.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   127052 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/crypto.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   294963 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/crypto.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    10018 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/crypto_app.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/dist/
│ │ │  -rw-r--r--   0 root         (0) root         (0)    20933 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/dist/handlebars.runtime-CFQAK6SD.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    33580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/dist/handlebars.templates-K7URE6B4.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    70589 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/dist/html-55NP3CS6.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    67213 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/crypto-5.5.3/doc/html/dist/html-erlang-WGRVP7UZ.css
│ │ │ @@ -546,15 +546,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    21770 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/assets/cond_break_dialog.jpg
│ │ │  -rw-r--r--   0 root         (0) root         (0)    13532 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/assets/function_break_dialog.jpg
│ │ │  -rw-r--r--   0 root         (0) root         (0)    28924 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/assets/interpret.jpg
│ │ │  -rw-r--r--   0 root         (0) root         (0)    14414 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/assets/line_break_dialog.jpg
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5837 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/assets/logo.png
│ │ │  -rw-r--r--   0 root         (0) root         (0)    40742 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/assets/monitor.jpg
│ │ │  -rw-r--r--   0 root         (0) root         (0)    34504 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/assets/view.jpg
│ │ │ --rw-r--r--   0 root         (0) root         (0)   219444 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/debugger.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   219447 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/debugger.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    13135 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/debugger.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    52048 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/debugger_chapter.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/dist/
│ │ │  -rw-r--r--   0 root         (0) root         (0)    20933 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/dist/handlebars.runtime-CFQAK6SD.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    33580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/dist/handlebars.templates-K7URE6B4.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    70589 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/dist/html-55NP3CS6.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    67213 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/debugger-5.5.0.1/doc/html/dist/html-erlang-WGRVP7UZ.css
│ │ │ @@ -583,15 +583,15 @@
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)      921 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/.build
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6028 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/404.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6794 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/api-reference.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/assets/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5837 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/assets/logo.png
│ │ │ --rw-r--r--   0 root         (0) root         (0)    66389 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dialyzer.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    66385 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dialyzer.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    53654 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dialyzer.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    25902 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dialyzer_chapter.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/
│ │ │  -rw-r--r--   0 root         (0) root         (0)    20933 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/handlebars.runtime-CFQAK6SD.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    33580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/handlebars.templates-K7URE6B4.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    70589 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/html-55NP3CS6.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    67213 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/html-erlang-WGRVP7UZ.css
│ │ │ @@ -604,29 +604,29 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)   122270 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/search_data-6D666814.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   122270 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/search_data-0488DFD4.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7336 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/dist/sidebar_items-F976ACE0.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      266 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   132207 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5944 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    10876 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/dialyzer-5.3.1/doc/html/typer_cmd.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1143 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/.build
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6034 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/404.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     8222 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/api-reference.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/assets/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5837 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/assets/logo.png
│ │ │ --rw-r--r--   0 root         (0) root         (0)   144222 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   144219 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   253956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    57599 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    29032 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter_codec.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    32274 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter_dict.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6784 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter_examples.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9532 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter_intro.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    21968 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/diameter-2.4.1.1/doc/html/diameter_make.html
│ │ │ @@ -789,15 +789,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)   193099 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/dist/search_data-1F14090C.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    15936 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/dist/sidebar_items-8A5CCEF3.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    73740 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/ei.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    72795 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/ei_connect.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    11739 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/ei_global.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    26982 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/ei_users_guide.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    22688 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/erl_call_cmd.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)    84945 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/erl_interface.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    84946 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/erl_interface.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)      272 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   110953 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5565 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/erl_interface-5.5.2/doc/html/search.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1332 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/.build
│ │ │ @@ -832,15 +832,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    80722 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/dist/search_data-07FF68FB.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9243 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/dist/sidebar_items-639C3385.js
│ │ │ --rw-r--r--   0 root         (0) root         (0)   302542 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   302539 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    22899 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    57168 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et_collector.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    52414 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et_desc.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   100534 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et_examples.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9916 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et_intro.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    20457 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et_selector.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    45778 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/et-1.7.1/doc/html/et_tutorial.html
│ │ │ @@ -873,15 +873,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    75635 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/dist/search_data-9EC16955.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     3043 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/dist/sidebar_items-3A2D003A.js
│ │ │ --rw-r--r--   0 root         (0) root         (0)    45179 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/eunit.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    45180 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/eunit.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    13587 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/eunit.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6634 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/eunit_surefire.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      263 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    38822 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5926 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/eunit-2.9.1/doc/html/search.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/
│ │ │ @@ -905,17 +905,17 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)    29403 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/search_data-D71AAFA6.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    29403 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/search_data-FF6A1601.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5270 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/dist/sidebar_items-B6B07F6E.js
│ │ │ --rw-r--r--   0 root         (0) root         (0)    33164 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/ftp.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    33167 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/ftp.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    82127 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/ftp.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12856 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/ftp_client.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      261 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7162 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/introduction.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    22515 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5914 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ftp-1.2.3/doc/html/search.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/
│ │ │ @@ -951,15 +951,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    11421 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/http_uri.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    91850 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/httpc.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   117910 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/httpd.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12136 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/httpd_custom_api.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    13448 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/httpd_socket.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    45124 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/httpd_util.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      265 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/index.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   152853 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/inets.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   152856 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/inets.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    25717 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/inets.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     8659 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/inets_services.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7466 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/introduction.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    21300 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/mod_alias.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    83168 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/mod_auth.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    19815 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/mod_esi.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    37282 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/inets-9.3.2.1/doc/html/mod_security.html
│ │ │ @@ -1138,15 +1138,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    57284 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/global.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    37262 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/global_group.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    24987 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/heart.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      267 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   184609 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/inet.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    86882 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/inet_res.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7733 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/introduction_chapter.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   790884 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/kernel.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   790883 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/kernel.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    42777 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/kernel_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   188467 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/logger.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   108811 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/logger_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    70518 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/logger_cookbook.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    15657 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/logger_disk_log_h.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    25586 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/logger_filters.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    34203 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/kernel-10.2.7.2/doc/html/logger_formatter.html
│ │ │ @@ -1198,15 +1198,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)   200183 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/dist/search_data-3F59FB08.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    33244 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/dist/sidebar_items-0FDD3384.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      264 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/index.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   181537 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   181544 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   199461 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    13680 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco_architecture.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9136 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco_codec_meas.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23098 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco_codec_mstone1.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9740 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco_codec_mstone2.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9712 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco_codec_transform.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    18676 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/megaco-4.7.2/doc/html/megaco_debug.html
│ │ │ @@ -1253,15 +1253,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)   375315 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/dist/search_data-48CBC29D.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    24530 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/dist/sidebar_items-845AA6F8.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      265 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/index.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   221930 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   221944 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   320920 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    45468 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia_app_a.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    87795 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia_app_b.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    46060 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia_app_c.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9869 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia_chap1.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   109095 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia_chap2.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    51394 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/mnesia-4.23.5/doc/html/mnesia_chap3.html
│ │ │ @@ -1308,15 +1308,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)   146200 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/dist/search_data-C92E6517.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12765 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/dist/sidebar_items-6D9D41B7.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17966 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/etop.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    15746 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/etop_ug.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      265 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7350 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/introduction_ug.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    71142 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/notes.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   116872 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/observer.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   116863 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/observer.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    13905 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/observer.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7238 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/observer_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23494 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/observer_ug.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5941 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   111935 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/ttb.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   165007 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/observer-2.17/doc/html/ttb_ug.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/
│ │ │ @@ -1343,22 +1343,22 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)    76343 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/search_data-465DEDF7.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    76343 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/search_data-D78563F6.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7406 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/dist/sidebar_items-19ECDBA9.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    13859 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/error_handling.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    51373 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/getting_started.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      261 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     8466 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/introduction.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    57071 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/notes.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)    67277 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/odbc.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    67278 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/odbc.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    76660 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/odbc.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5917 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/odbc-2.15/doc/html/search.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)      952 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/.build
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6019 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/404.html
│ │ │ @@ -1387,15 +1387,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    69231 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/dist/search_data-D20C2403.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7923 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/dist/sidebar_items-CB1A13C5.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      265 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    31358 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/memsup.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    57043 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    14802 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/nteventlog.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)    50283 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/os_mon.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    50284 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/os_mon.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9983 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/os_mon_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    22952 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/os_sup.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5935 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/os_mon-2.10.1/doc/html/search.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)      890 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/.build
│ │ │ @@ -1422,15 +1422,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    55131 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/dist/search_data-5B3B164D.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5679 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/dist/sidebar_items-E70C9F62.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      266 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    55824 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/leex.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    37754 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/notes.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)    44439 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/parsetools.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    44436 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/parsetools.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5950 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    67892 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/parsetools-2.6/doc/html/yecc.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)      952 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/.build
│ │ │  -rw-r--r--   0 root         (0) root         (0)     6049 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/404.html
│ │ │ @@ -1455,15 +1455,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)   145165 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/dist/search_data-3C8D465E.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    16466 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/dist/sidebar_items-6446AF99.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      271 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    90723 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/notes.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   100056 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/public_key.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   100048 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/public_key.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   207172 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/public_key.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    10281 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/public_key_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    70652 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/public_key_records.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5965 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   131335 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/public_key-1.17.1.1/doc/html/using_public_key.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/
│ │ │ @@ -1491,15 +1491,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    90283 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/dist/search_data-8726EDEC.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     8840 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/dist/sidebar_items-DF937488.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      265 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    46277 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/notes.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)    62891 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/reltool.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    62878 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/reltool.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   100617 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/reltool.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   199744 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/reltool_examples.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/reltool_intro.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23138 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/reltool_usage.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5938 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/reltool-1.0.1/doc/html/search.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/
│ │ │ @@ -1524,24 +1524,24 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)   161570 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/search_data-A1188F1F.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   161570 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/search_data-1DC1D27C.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    18284 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dist/sidebar_items-E5CACCF4.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9774 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dtrace.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    47868 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/dyntrace.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      271 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    50868 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/instrument.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    64811 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/lttng.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    50067 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/msacc.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    78751 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/notes.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   118757 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/runtime_tools.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   118745 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/runtime_tools.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7584 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/runtime_tools_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    29115 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/scheduler.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5974 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12911 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/system_information.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9992 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/runtime_tools-2.1.1/doc/html/systemtap.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/
│ │ │ @@ -1576,15 +1576,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    34663 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/error_logging.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      262 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    70067 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    42546 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/rb.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12220 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/rel.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    80519 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/release_handler.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9577 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/relup.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)    92274 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/sasl.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    92278 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/sasl.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17193 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/sasl_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7699 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/sasl_intro.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17269 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/script.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5920 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    40703 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/sasl-4.2.2/doc/html/systools.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/
│ │ │ @@ -1623,15 +1623,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)   549455 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/dist/search_data-18B48D27.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    90029 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/dist/sidebar_items-E4326166.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      263 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    61226 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5923 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/search.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   443714 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   443711 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   148375 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    39983 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp_advanced_agent.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    62881 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp_agent_config_files.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    51341 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp_agent_funct_descr.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    18123 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp_agent_netif.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    66609 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     8609 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/snmp-5.18.2/doc/html/snmp_app_a.html
│ │ │ @@ -1707,22 +1707,22 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)   368072 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/search_data-E0401131.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   368072 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/search_data-AAB6B0F2.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    45936 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/dist/sidebar_items-F32BF3C6.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23928 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/hardening.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      264 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    14206 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/introduction.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   231444 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5923 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/search.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   272661 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   272667 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   250454 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    24859 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh_agent.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    25480 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    44362 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh_client_channel.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23335 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh_client_key_api.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    78399 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh_connection.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    49063 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssh-5.2.11.3/doc/html/ssh_file.html
│ │ │ @@ -1754,20 +1754,20 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)   486276 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/search_data-2DAE4F8E.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   486276 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/search_data-31FB6662.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    27242 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/dist/sidebar_items-617A7806.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)      265 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   254708 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5926 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/search.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   210317 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   210310 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   316851 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17362 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12890 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl_crl_cache.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    21815 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl_crl_cache_api.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    39368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl_distribution.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    14213 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl_protocol.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    25887 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/ssl-11.2.12.3/doc/html/ssl_session_cache_api.html
│ │ │ @@ -1865,15 +1865,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5938 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    47248 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/sets.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   106196 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/shell.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    10144 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/shell_default.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    49822 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/shell_docs.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    33204 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/slave.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   354762 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/sofs.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)  1410495 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/stdlib.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)  1410529 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/stdlib.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    15682 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/stdlib_app.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   191516 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/string.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    93086 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/supervisor.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    20623 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/supervisor_bridge.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   107262 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/sys.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    81680 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/timer.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    75028 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/stdlib-6.2.2.2/doc/html/unicode.html
│ │ │ @@ -1906,15 +1906,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)   212519 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/search_data-1D7BB8C0.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   212519 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/search_data-B09DB05B.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    52682 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/dist/sidebar_items-2B4A1108.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)    37822 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/epp_dodger.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17453 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_comment_scan.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    39814 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_prettypr.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17404 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_recomment.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   509513 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_syntax.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   112150 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/syntax_tools-3.2.2.2/doc/html/erl_syntax_lib.html
│ │ │ @@ -1946,15 +1946,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23236 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23580 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)    23040 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5624 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5472 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5368 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1956 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/remixicon-NKANDIL5.woff2
│ │ │ --rw-r--r--   0 root         (0) root         (0)    22267 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/search_data-7B342769.js
│ │ │ +-rw-r--r--   0 root         (0) root         (0)    22267 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/search_data-BA5DB564.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     3043 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/dist/sidebar_items-3CBBBF05.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)     9543 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/getting_started.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      262 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     7929 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/introduction.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    14778 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5920 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    28826 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tftp-1.2.2/doc/html/tftp.epub
│ │ │ @@ -2002,15 +2002,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)      263 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    67398 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/lcnt.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    53417 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/lcnt_chapter.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    18424 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/make.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   106923 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5926 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/search.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    28575 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/tags.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)   239549 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/tools.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)   239545 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/tools.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)   173731 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/tprof.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)   184557 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/xref.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    39616 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/tools-4.1.1/doc/html/xref_chapter.html
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/
│ │ │  drwxr-xr-x   0 root         (0) root         (0)        0 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/
│ │ │  -rw-r--r--   0 root         (0) root         (0)     1612 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/.build.gz
│ │ │ @@ -2040,15 +2040,15 @@
│ │ │  -rw-r--r--   0 root         (0) root         (0)  1664774 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/dist/search_data-7BF0929D.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)   578643 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/dist/sidebar_items-A20B6997.js
│ │ │  -rw-r--r--   0 root         (0) root         (0)  1720397 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/gl.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    77340 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/glu.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)      260 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/index.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    58699 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/notes.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)     5908 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/search.html
│ │ │ --rw-r--r--   0 root         (0) root         (0)  1607143 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wx.epub
│ │ │ +-rw-r--r--   0 root         (0) root         (0)  1607142 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wx.epub
│ │ │  -rw-r--r--   0 root         (0) root         (0)    54017 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wx.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    19452 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wxAcceleratorEntry.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    15130 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wxAcceleratorTable.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    12373 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wxActivateEvent.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    19127 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wxArtProvider.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    17639 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wxAuiDockArt.html
│ │ │  -rw-r--r--   0 root         (0) root         (0)    63043 2025-10-31 11:57:11.000000 ./usr/share/doc/erlang-doc/html/lib/wx-2.4.3/doc/html/wxAuiManager.html
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/Erlang System Documentation.epub
│ │ │ ├── zipinfo {}
│ │ │ │ @@ -1,93 +1,93 @@
│ │ │ │ -Zip file size: 654589 bytes, number of entries: 91
│ │ │ │ -?rw-r--r--  6.1 unx       20 bx stor 25-Oct-31 13:18 mimetype
│ │ │ │ -?rw-r--r--  6.1 unx    17922 bx defN 25-Oct-31 13:18 OEBPS/versions.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     4673 bx defN 25-Oct-31 13:18 OEBPS/upgrade.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    53439 bx defN 25-Oct-31 13:18 OEBPS/typespec.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     2166 bx defN 25-Oct-31 13:18 OEBPS/tutorial.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx      764 bx defN 25-Oct-31 13:18 OEBPS/title.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    46256 bx defN 25-Oct-31 13:18 OEBPS/tablesdatabases.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    12466 bx defN 25-Oct-31 13:18 OEBPS/system_principles.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     7346 bx defN 25-Oct-31 13:18 OEBPS/system_limits.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    63476 bx defN 25-Oct-31 13:18 OEBPS/sup_princ.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx   253918 bx defN 25-Oct-31 13:18 OEBPS/statem.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx   111264 bx defN 25-Oct-31 13:18 OEBPS/spec_proc.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx   249951 bx defN 25-Oct-31 13:18 OEBPS/seq_prog.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    70943 bx defN 25-Oct-31 13:18 OEBPS/robustness.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    20854 bx defN 25-Oct-31 13:18 OEBPS/release_structure.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    59888 bx defN 25-Oct-31 13:18 OEBPS/release_handling.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     4596 bx defN 25-Oct-31 13:18 OEBPS/reference_manual.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    19455 bx defN 25-Oct-31 13:18 OEBPS/ref_man_records.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    48276 bx defN 25-Oct-31 13:18 OEBPS/ref_man_processes.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    14454 bx defN 25-Oct-31 13:18 OEBPS/ref_man_functions.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    49542 bx defN 25-Oct-31 13:18 OEBPS/records_macros.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     2190 bx defN 25-Oct-31 13:18 OEBPS/readme.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx      785 bx defN 25-Oct-31 13:18 OEBPS/programming_examples.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    40147 bx defN 25-Oct-31 13:18 OEBPS/prog_ex_records.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    15206 bx defN 25-Oct-31 13:18 OEBPS/profiling.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     8501 bx defN 25-Oct-31 13:18 OEBPS/ports.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     3737 bx defN 25-Oct-31 13:18 OEBPS/patterns.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    13417 bx defN 25-Oct-31 13:18 OEBPS/overview.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     8959 bx defN 25-Oct-31 13:18 OEBPS/otp-patch-apply.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     9082 bx defN 25-Oct-31 13:18 OEBPS/opaques.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    14065 bx defN 25-Oct-31 13:18 OEBPS/nif.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     6367 bx defN 25-Oct-31 13:18 OEBPS/nav.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    25842 bx defN 25-Oct-31 13:18 OEBPS/modules.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     7012 bx defN 25-Oct-31 13:18 OEBPS/misc.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     5477 bx defN 25-Oct-31 13:18 OEBPS/memory.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    45509 bx defN 25-Oct-31 13:18 OEBPS/maps.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    39594 bx defN 25-Oct-31 13:18 OEBPS/macros.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    31439 bx defN 25-Oct-31 13:18 OEBPS/listhandling.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    42996 bx defN 25-Oct-31 13:18 OEBPS/list_comprehensions.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     2211 bx defN 25-Oct-31 13:18 OEBPS/installation_guide.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    55516 bx defN 25-Oct-31 13:18 OEBPS/install.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    28229 bx defN 25-Oct-31 13:18 OEBPS/install-win32.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    35715 bx defN 25-Oct-31 13:18 OEBPS/install-cross.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    20858 bx defN 25-Oct-31 13:18 OEBPS/included_applications.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     2353 bx defN 25-Oct-31 13:18 OEBPS/getting_started.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    31341 bx defN 25-Oct-31 13:18 OEBPS/gen_server_concepts.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx   118675 bx defN 25-Oct-31 13:18 OEBPS/funs.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     8453 bx defN 25-Oct-31 13:18 OEBPS/features.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx   255000 bx defN 25-Oct-31 13:18 OEBPS/expressions.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     2365 bx defN 25-Oct-31 13:18 OEBPS/example.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    26747 bx defN 25-Oct-31 13:18 OEBPS/events.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    16629 bx defN 25-Oct-31 13:18 OEBPS/errors.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    13609 bx defN 25-Oct-31 13:18 OEBPS/error_logging.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    42501 bx defN 25-Oct-31 13:18 OEBPS/erl_interface.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    18220 bx defN 25-Oct-31 13:18 OEBPS/embedded.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     2085 bx defN 25-Oct-31 13:18 OEBPS/efficiency_guide.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    46447 bx defN 25-Oct-31 13:18 OEBPS/eff_guide_processes.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    21209 bx defN 25-Oct-31 13:18 OEBPS/eff_guide_functions.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     9338 bx defN 25-Oct-31 13:18 OEBPS/drivers.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    47180 bx defN 25-Oct-31 13:18 OEBPS/documentation.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    14892 bx defN 25-Oct-31 13:18 OEBPS/distributed_applications.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    24284 bx defN 25-Oct-31 13:18 OEBPS/distributed.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    14562 bx defN 25-Oct-31 13:18 OEBPS/dist/epub-erlang-ESPT6BQV.css
│ │ │ │ -?rw-r--r--  6.1 unx      499 bx defN 25-Oct-31 13:18 OEBPS/dist/epub-LSJCIYTM.js
│ │ │ │ -?rw-r--r--  6.1 unx    36780 bx defN 25-Oct-31 13:18 OEBPS/design_principles.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    15003 bx defN 25-Oct-31 13:18 OEBPS/debugging.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    71771 bx defN 25-Oct-31 13:18 OEBPS/data_types.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx   115067 bx defN 25-Oct-31 13:18 OEBPS/create_target.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    13187 bx defN 25-Oct-31 13:18 OEBPS/content.opf
│ │ │ │ -?rw-r--r--  6.1 unx   129900 bx defN 25-Oct-31 13:18 OEBPS/conc_prog.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    33231 bx defN 25-Oct-31 13:18 OEBPS/commoncaveats.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    11935 bx defN 25-Oct-31 13:18 OEBPS/code_loading.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx      803 bx defN 25-Oct-31 13:18 OEBPS/cnode.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     5177 bx defN 25-Oct-31 13:18 OEBPS/character_set.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    40707 bx defN 25-Oct-31 13:18 OEBPS/c_portdriver.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    35510 bx defN 25-Oct-31 13:18 OEBPS/c_port.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    34819 bx defN 25-Oct-31 13:18 OEBPS/bit_syntax.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    53327 bx defN 25-Oct-31 13:18 OEBPS/binaryhandling.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     7606 bx defN 25-Oct-31 13:18 OEBPS/benchmarking.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx     5837 bx defN 25-Oct-31 13:18 OEBPS/assets/logo.png
│ │ │ │ -?rw-r--r--  6.1 unx     5837 bx defN 25-Oct-31 13:18 OEBPS/assets/erlang-logo.png
│ │ │ │ -?rw-r--r--  6.1 unx     7044 bx stor 25-Oct-31 13:18 OEBPS/assets/dist5.gif
│ │ │ │ -?rw-r--r--  6.1 unx     2939 bx stor 25-Oct-31 13:18 OEBPS/assets/dist4.gif
│ │ │ │ -?rw-r--r--  6.1 unx     5007 bx stor 25-Oct-31 13:18 OEBPS/assets/dist3.gif
│ │ │ │ -?rw-r--r--  6.1 unx     5214 bx stor 25-Oct-31 13:18 OEBPS/assets/dist2.gif
│ │ │ │ -?rw-r--r--  6.1 unx     2284 bx stor 25-Oct-31 13:18 OEBPS/assets/dist1.gif
│ │ │ │ -?rw-r--r--  6.1 unx     7982 bx stor 25-Oct-31 13:18 OEBPS/assets/ballpoint-pen.svg
│ │ │ │ -?rw-r--r--  6.1 unx    91721 bx defN 25-Oct-31 13:18 OEBPS/appup_cookbook.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx    47722 bx defN 25-Oct-31 13:18 OEBPS/applications.xhtml
│ │ │ │ -?rw-r--r--  6.1 unx      252 bx defN 25-Oct-31 13:18 META-INF/container.xml
│ │ │ │ -?rw-r--r--  6.1 unx      162 bx defN 25-Oct-31 13:18 META-INF/com.apple.ibooks.display-options.xml
│ │ │ │ -91 files, 3077736 bytes uncompressed, 638657 bytes compressed:  79.3%
│ │ │ │ +Zip file size: 654626 bytes, number of entries: 91
│ │ │ │ +?rw-r--r--  6.1 unx       20 bx stor 25-Oct-31 15:24 mimetype
│ │ │ │ +?rw-r--r--  6.1 unx    17922 bx defN 25-Oct-31 15:24 OEBPS/versions.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     4673 bx defN 25-Oct-31 15:24 OEBPS/upgrade.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    53439 bx defN 25-Oct-31 15:24 OEBPS/typespec.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     2166 bx defN 25-Oct-31 15:24 OEBPS/tutorial.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx      764 bx defN 25-Oct-31 15:24 OEBPS/title.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    46256 bx defN 25-Oct-31 15:24 OEBPS/tablesdatabases.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    12466 bx defN 25-Oct-31 15:24 OEBPS/system_principles.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     7346 bx defN 25-Oct-31 15:24 OEBPS/system_limits.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    63476 bx defN 25-Oct-31 15:24 OEBPS/sup_princ.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx   253918 bx defN 25-Oct-31 15:24 OEBPS/statem.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx   111264 bx defN 25-Oct-31 15:24 OEBPS/spec_proc.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx   249951 bx defN 25-Oct-31 15:24 OEBPS/seq_prog.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    70943 bx defN 25-Oct-31 15:24 OEBPS/robustness.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    20854 bx defN 25-Oct-31 15:24 OEBPS/release_structure.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    59888 bx defN 25-Oct-31 15:24 OEBPS/release_handling.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     4596 bx defN 25-Oct-31 15:24 OEBPS/reference_manual.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    19455 bx defN 25-Oct-31 15:24 OEBPS/ref_man_records.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    48276 bx defN 25-Oct-31 15:24 OEBPS/ref_man_processes.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    14454 bx defN 25-Oct-31 15:24 OEBPS/ref_man_functions.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    49542 bx defN 25-Oct-31 15:24 OEBPS/records_macros.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     2190 bx defN 25-Oct-31 15:24 OEBPS/readme.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx      785 bx defN 25-Oct-31 15:24 OEBPS/programming_examples.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    40147 bx defN 25-Oct-31 15:24 OEBPS/prog_ex_records.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    15206 bx defN 25-Oct-31 15:24 OEBPS/profiling.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     8501 bx defN 25-Oct-31 15:24 OEBPS/ports.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     3737 bx defN 25-Oct-31 15:24 OEBPS/patterns.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    13417 bx defN 25-Oct-31 15:24 OEBPS/overview.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     8959 bx defN 25-Oct-31 15:24 OEBPS/otp-patch-apply.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     9082 bx defN 25-Oct-31 15:24 OEBPS/opaques.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    14065 bx defN 25-Oct-31 15:24 OEBPS/nif.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     6367 bx defN 25-Oct-31 15:24 OEBPS/nav.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    25842 bx defN 25-Oct-31 15:24 OEBPS/modules.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     7012 bx defN 25-Oct-31 15:24 OEBPS/misc.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     5477 bx defN 25-Oct-31 15:24 OEBPS/memory.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    45509 bx defN 25-Oct-31 15:24 OEBPS/maps.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    39594 bx defN 25-Oct-31 15:24 OEBPS/macros.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    31439 bx defN 25-Oct-31 15:24 OEBPS/listhandling.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    42996 bx defN 25-Oct-31 15:24 OEBPS/list_comprehensions.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     2211 bx defN 25-Oct-31 15:24 OEBPS/installation_guide.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    55516 bx defN 25-Oct-31 15:24 OEBPS/install.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    28229 bx defN 25-Oct-31 15:24 OEBPS/install-win32.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    35715 bx defN 25-Oct-31 15:24 OEBPS/install-cross.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    20858 bx defN 25-Oct-31 15:24 OEBPS/included_applications.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     2353 bx defN 25-Oct-31 15:24 OEBPS/getting_started.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    31341 bx defN 25-Oct-31 15:24 OEBPS/gen_server_concepts.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx   118675 bx defN 25-Oct-31 15:24 OEBPS/funs.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     8453 bx defN 25-Oct-31 15:24 OEBPS/features.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx   255000 bx defN 25-Oct-31 15:24 OEBPS/expressions.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     2365 bx defN 25-Oct-31 15:24 OEBPS/example.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    26747 bx defN 25-Oct-31 15:24 OEBPS/events.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    16629 bx defN 25-Oct-31 15:24 OEBPS/errors.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    13609 bx defN 25-Oct-31 15:24 OEBPS/error_logging.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    42501 bx defN 25-Oct-31 15:24 OEBPS/erl_interface.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    18220 bx defN 25-Oct-31 15:24 OEBPS/embedded.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     2085 bx defN 25-Oct-31 15:24 OEBPS/efficiency_guide.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    46447 bx defN 25-Oct-31 15:24 OEBPS/eff_guide_processes.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    21209 bx defN 25-Oct-31 15:24 OEBPS/eff_guide_functions.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     9338 bx defN 25-Oct-31 15:24 OEBPS/drivers.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    47180 bx defN 25-Oct-31 15:24 OEBPS/documentation.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    14892 bx defN 25-Oct-31 15:24 OEBPS/distributed_applications.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    24284 bx defN 25-Oct-31 15:24 OEBPS/distributed.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    14562 bx defN 25-Oct-31 15:24 OEBPS/dist/epub-erlang-ESPT6BQV.css
│ │ │ │ +?rw-r--r--  6.1 unx      499 bx defN 25-Oct-31 15:24 OEBPS/dist/epub-LSJCIYTM.js
│ │ │ │ +?rw-r--r--  6.1 unx    36780 bx defN 25-Oct-31 15:24 OEBPS/design_principles.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    15003 bx defN 25-Oct-31 15:24 OEBPS/debugging.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    71771 bx defN 25-Oct-31 15:24 OEBPS/data_types.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx   115067 bx defN 25-Oct-31 15:24 OEBPS/create_target.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    13187 bx defN 25-Oct-31 15:24 OEBPS/content.opf
│ │ │ │ +?rw-r--r--  6.1 unx   129900 bx defN 25-Oct-31 15:24 OEBPS/conc_prog.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    33231 bx defN 25-Oct-31 15:24 OEBPS/commoncaveats.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    11935 bx defN 25-Oct-31 15:24 OEBPS/code_loading.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx      803 bx defN 25-Oct-31 15:24 OEBPS/cnode.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     5177 bx defN 25-Oct-31 15:24 OEBPS/character_set.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    40707 bx defN 25-Oct-31 15:24 OEBPS/c_portdriver.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    35510 bx defN 25-Oct-31 15:24 OEBPS/c_port.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    34819 bx defN 25-Oct-31 15:24 OEBPS/bit_syntax.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    53327 bx defN 25-Oct-31 15:24 OEBPS/binaryhandling.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     7606 bx defN 25-Oct-31 15:24 OEBPS/benchmarking.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx     5837 bx defN 25-Oct-31 15:24 OEBPS/assets/logo.png
│ │ │ │ +?rw-r--r--  6.1 unx     5837 bx defN 25-Oct-31 15:24 OEBPS/assets/erlang-logo.png
│ │ │ │ +?rw-r--r--  6.1 unx     7044 bx stor 25-Oct-31 15:24 OEBPS/assets/dist5.gif
│ │ │ │ +?rw-r--r--  6.1 unx     2939 bx stor 25-Oct-31 15:24 OEBPS/assets/dist4.gif
│ │ │ │ +?rw-r--r--  6.1 unx     5007 bx stor 25-Oct-31 15:24 OEBPS/assets/dist3.gif
│ │ │ │ +?rw-r--r--  6.1 unx     5214 bx stor 25-Oct-31 15:24 OEBPS/assets/dist2.gif
│ │ │ │ +?rw-r--r--  6.1 unx     2284 bx stor 25-Oct-31 15:24 OEBPS/assets/dist1.gif
│ │ │ │ +?rw-r--r--  6.1 unx     7982 bx stor 25-Oct-31 15:24 OEBPS/assets/ballpoint-pen.svg
│ │ │ │ +?rw-r--r--  6.1 unx    91721 bx defN 25-Oct-31 15:24 OEBPS/appup_cookbook.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx    47722 bx defN 25-Oct-31 15:24 OEBPS/applications.xhtml
│ │ │ │ +?rw-r--r--  6.1 unx      252 bx defN 25-Oct-31 15:24 META-INF/container.xml
│ │ │ │ +?rw-r--r--  6.1 unx      162 bx defN 25-Oct-31 15:24 META-INF/com.apple.ibooks.display-options.xml
│ │ │ │ +91 files, 3077736 bytes uncompressed, 638694 bytes compressed:  79.3%
│ │ │ ├── zipdetails --redact --walk --utc {}
│ │ │ │ @@ -1,29 +1,29 @@
│ │ │ │  
│ │ │ │  00000 LOCAL HEADER #1       04034B50 (67324752)
│ │ │ │  00004 Extract Zip Spec      0A (10) '1.0'
│ │ │ │  00005 Extract OS            00 (0) 'MS-DOS'
│ │ │ │  00006 General Purpose Flag  0000 (0)
│ │ │ │  00008 Compression Method    0000 (0) 'Stored'
│ │ │ │ -0000A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ +0000A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │  0000E CRC                   2CAB616F (749429103)
│ │ │ │  00012 Compressed Size       00000014 (20)
│ │ │ │  00016 Uncompressed Size     00000014 (20)
│ │ │ │  0001A Filename Length       0008 (8)
│ │ │ │  0001C Extra Length          001C (28)
│ │ │ │  0001E Filename              'XXXXXXXX'
│ │ │ │  #
│ │ │ │  # WARNING: Offset 0x1E: Filename 'XXXXXXXX'
│ │ │ │  #          Zero length filename
│ │ │ │  #
│ │ │ │  00026 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │  00028   Length              0009 (9)
│ │ │ │  0002A   Flags               03 (3) 'Modification Access'
│ │ │ │ -0002B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -0002F   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ +0002B   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +0002F   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │  00033 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │  00035   Length              000B (11)
│ │ │ │  00037   Version             01 (1)
│ │ │ │  00038   UID Size            04 (4)
│ │ │ │  00039   UID                 00000000 (0)
│ │ │ │  0003D   GID Size            04 (4)
│ │ │ │  0003E   GID                 00000000 (0)
│ │ │ │ @@ -31,30 +31,30 @@
│ │ │ │  
│ │ │ │  00056 LOCAL HEADER #2       04034B50 (67324752)
│ │ │ │  0005A Extract Zip Spec      14 (20) '2.0'
│ │ │ │  0005B Extract OS            00 (0) 'MS-DOS'
│ │ │ │  0005C General Purpose Flag  0000 (0)
│ │ │ │        [Bits 1-2]            0 'Normal Compression'
│ │ │ │  0005E Compression Method    0008 (8) 'Deflated'
│ │ │ │ -00060 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ +00060 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │  00064 CRC                   203D4469 (540886121)
│ │ │ │  00068 Compressed Size       000015AD (5549)
│ │ │ │  0006C Uncompressed Size     00004602 (17922)
│ │ │ │  00070 Filename Length       0014 (20)
│ │ │ │  00072 Extra Length          001C (28)
│ │ │ │  00074 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │  #
│ │ │ │  # WARNING: Offset 0x74: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │  #          Zero length filename
│ │ │ │  #
│ │ │ │  00088 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │  0008A   Length              0009 (9)
│ │ │ │  0008C   Flags               03 (3) 'Modification Access'
│ │ │ │ -0008D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -00091   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ +0008D   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +00091   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │  00095 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │  00097   Length              000B (11)
│ │ │ │  00099   Version             01 (1)
│ │ │ │  0009A   UID Size            04 (4)
│ │ │ │  0009B   UID                 00000000 (0)
│ │ │ │  0009F   GID Size            04 (4)
│ │ │ │  000A0   GID                 00000000 (0)
│ │ │ │ @@ -62,30 +62,30 @@
│ │ │ │  
│ │ │ │  01651 LOCAL HEADER #3       04034B50 (67324752)
│ │ │ │  01655 Extract Zip Spec      14 (20) '2.0'
│ │ │ │  01656 Extract OS            00 (0) 'MS-DOS'
│ │ │ │  01657 General Purpose Flag  0000 (0)
│ │ │ │        [Bits 1-2]            0 'Normal Compression'
│ │ │ │  01659 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -0165B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ +0165B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │  0165F CRC                   1EC1D7C5 (516020165)
│ │ │ │  01663 Compressed Size       000006D5 (1749)
│ │ │ │  01667 Uncompressed Size     00001241 (4673)
│ │ │ │  0166B Filename Length       0013 (19)
│ │ │ │  0166D Extra Length          001C (28)
│ │ │ │  0166F Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │  #
│ │ │ │  # WARNING: Offset 0x166F: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │  #          Zero length filename
│ │ │ │  #
│ │ │ │  01682 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │  01684   Length              0009 (9)
│ │ │ │  01686   Flags               03 (3) 'Modification Access'
│ │ │ │ -01687   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -0168B   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ +01687   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +0168B   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │  0168F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │  01691   Length              000B (11)
│ │ │ │  01693   Version             01 (1)
│ │ │ │  01694   UID Size            04 (4)
│ │ │ │  01695   UID                 00000000 (0)
│ │ │ │  01699   GID Size            04 (4)
│ │ │ │  0169A   GID                 00000000 (0)
│ │ │ │ @@ -93,6187 +93,6187 @@
│ │ │ │  
│ │ │ │  01D73 LOCAL HEADER #4       04034B50 (67324752)
│ │ │ │  01D77 Extract Zip Spec      14 (20) '2.0'
│ │ │ │  01D78 Extract OS            00 (0) 'MS-DOS'
│ │ │ │  01D79 General Purpose Flag  0000 (0)
│ │ │ │        [Bits 1-2]            0 'Normal Compression'
│ │ │ │  01D7B Compression Method    0008 (8) 'Deflated'
│ │ │ │ -01D7D Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -01D81 CRC                   DD59CFB1 (3713650609)
│ │ │ │ -01D85 Compressed Size       00002DA9 (11689)
│ │ │ │ +01D7D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +01D81 CRC                   7FB0954F (2142278991)
│ │ │ │ +01D85 Compressed Size       00002DA0 (11680)
│ │ │ │  01D89 Uncompressed Size     0000D0BF (53439)
│ │ │ │  01D8D Filename Length       0014 (20)
│ │ │ │  01D8F Extra Length          001C (28)
│ │ │ │  01D91 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │  #
│ │ │ │  # WARNING: Offset 0x1D91: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │  #          Zero length filename
│ │ │ │  #
│ │ │ │  01DA5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │  01DA7   Length              0009 (9)
│ │ │ │  01DA9   Flags               03 (3) 'Modification Access'
│ │ │ │ -01DAA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -01DAE   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ +01DAA   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +01DAE   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │  01DB2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │  01DB4   Length              000B (11)
│ │ │ │  01DB6   Version             01 (1)
│ │ │ │  01DB7   UID Size            04 (4)
│ │ │ │  01DB8   UID                 00000000 (0)
│ │ │ │  01DBC   GID Size            04 (4)
│ │ │ │  01DBD   GID                 00000000 (0)
│ │ │ │  01DC1 PAYLOAD
│ │ │ │  
│ │ │ │ -04B6A LOCAL HEADER #5       04034B50 (67324752)
│ │ │ │ -04B6E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -04B6F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -04B70 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -04B72 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -04B74 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -04B78 CRC                   B8F4A452 (3103040594)
│ │ │ │ -04B7C Compressed Size       000003F0 (1008)
│ │ │ │ -04B80 Uncompressed Size     00000876 (2166)
│ │ │ │ -04B84 Filename Length       0014 (20)
│ │ │ │ -04B86 Extra Length          001C (28)
│ │ │ │ -04B88 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x4B88: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -04B9C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -04B9E   Length              0009 (9)
│ │ │ │ -04BA0   Flags               03 (3) 'Modification Access'
│ │ │ │ -04BA1   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -04BA5   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -04BA9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -04BAB   Length              000B (11)
│ │ │ │ -04BAD   Version             01 (1)
│ │ │ │ -04BAE   UID Size            04 (4)
│ │ │ │ -04BAF   UID                 00000000 (0)
│ │ │ │ -04BB3   GID Size            04 (4)
│ │ │ │ -04BB4   GID                 00000000 (0)
│ │ │ │ -04BB8 PAYLOAD
│ │ │ │ -
│ │ │ │ -04FA8 LOCAL HEADER #6       04034B50 (67324752)
│ │ │ │ -04FAC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -04FAD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -04FAE General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -04FB0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -04FB2 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -04FB6 CRC                   D32DA388 (3542983560)
│ │ │ │ -04FBA Compressed Size       000001AE (430)
│ │ │ │ -04FBE Uncompressed Size     000002FC (764)
│ │ │ │ -04FC2 Filename Length       0011 (17)
│ │ │ │ -04FC4 Extra Length          001C (28)
│ │ │ │ -04FC6 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x4FC6: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -04FD7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -04FD9   Length              0009 (9)
│ │ │ │ -04FDB   Flags               03 (3) 'Modification Access'
│ │ │ │ -04FDC   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -04FE0   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -04FE4 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -04FE6   Length              000B (11)
│ │ │ │ -04FE8   Version             01 (1)
│ │ │ │ -04FE9   UID Size            04 (4)
│ │ │ │ -04FEA   UID                 00000000 (0)
│ │ │ │ -04FEE   GID Size            04 (4)
│ │ │ │ -04FEF   GID                 00000000 (0)
│ │ │ │ -04FF3 PAYLOAD
│ │ │ │ -
│ │ │ │ -051A1 LOCAL HEADER #7       04034B50 (67324752)
│ │ │ │ -051A5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -051A6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -051A7 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -051A9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -051AB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -051AF CRC                   D5BF807E (3586097278)
│ │ │ │ -051B3 Compressed Size       000020C6 (8390)
│ │ │ │ -051B7 Uncompressed Size     0000B4B0 (46256)
│ │ │ │ -051BB Filename Length       001B (27)
│ │ │ │ -051BD Extra Length          001C (28)
│ │ │ │ -051BF Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x51BF: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -051DA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -051DC   Length              0009 (9)
│ │ │ │ -051DE   Flags               03 (3) 'Modification Access'
│ │ │ │ -051DF   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -051E3   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -051E7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -051E9   Length              000B (11)
│ │ │ │ -051EB   Version             01 (1)
│ │ │ │ -051EC   UID Size            04 (4)
│ │ │ │ -051ED   UID                 00000000 (0)
│ │ │ │ -051F1   GID Size            04 (4)
│ │ │ │ -051F2   GID                 00000000 (0)
│ │ │ │ -051F6 PAYLOAD
│ │ │ │ -
│ │ │ │ -072BC LOCAL HEADER #8       04034B50 (67324752)
│ │ │ │ -072C0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -072C1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -072C2 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -072C4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -072C6 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -072CA CRC                   CB35CCED (3409300717)
│ │ │ │ -072CE Compressed Size       00000E6F (3695)
│ │ │ │ -072D2 Uncompressed Size     000030B2 (12466)
│ │ │ │ -072D6 Filename Length       001D (29)
│ │ │ │ -072D8 Extra Length          001C (28)
│ │ │ │ -072DA Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x72DA: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -072F7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -072F9   Length              0009 (9)
│ │ │ │ -072FB   Flags               03 (3) 'Modification Access'
│ │ │ │ -072FC   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -07300   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -07304 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -07306   Length              000B (11)
│ │ │ │ -07308   Version             01 (1)
│ │ │ │ -07309   UID Size            04 (4)
│ │ │ │ -0730A   UID                 00000000 (0)
│ │ │ │ -0730E   GID Size            04 (4)
│ │ │ │ -0730F   GID                 00000000 (0)
│ │ │ │ -07313 PAYLOAD
│ │ │ │ -
│ │ │ │ -08182 LOCAL HEADER #9       04034B50 (67324752)
│ │ │ │ -08186 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -08187 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -08188 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -0818A Compression Method    0008 (8) 'Deflated'
│ │ │ │ -0818C Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -08190 CRC                   D01F57B3 (3491714995)
│ │ │ │ -08194 Compressed Size       00000972 (2418)
│ │ │ │ -08198 Uncompressed Size     00001CB2 (7346)
│ │ │ │ -0819C Filename Length       0019 (25)
│ │ │ │ -0819E Extra Length          001C (28)
│ │ │ │ -081A0 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x81A0: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -081B9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -081BB   Length              0009 (9)
│ │ │ │ -081BD   Flags               03 (3) 'Modification Access'
│ │ │ │ -081BE   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -081C2   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -081C6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -081C8   Length              000B (11)
│ │ │ │ -081CA   Version             01 (1)
│ │ │ │ -081CB   UID Size            04 (4)
│ │ │ │ -081CC   UID                 00000000 (0)
│ │ │ │ -081D0   GID Size            04 (4)
│ │ │ │ -081D1   GID                 00000000 (0)
│ │ │ │ -081D5 PAYLOAD
│ │ │ │ -
│ │ │ │ -08B47 LOCAL HEADER #10      04034B50 (67324752)
│ │ │ │ -08B4B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -08B4C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -08B4D General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -08B4F Compression Method    0008 (8) 'Deflated'
│ │ │ │ -08B51 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -08B55 CRC                   92DCCD7D (2463944061)
│ │ │ │ -08B59 Compressed Size       0000387F (14463)
│ │ │ │ -08B5D Uncompressed Size     0000F7F4 (63476)
│ │ │ │ -08B61 Filename Length       0015 (21)
│ │ │ │ -08B63 Extra Length          001C (28)
│ │ │ │ -08B65 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x8B65: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -08B7A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -08B7C   Length              0009 (9)
│ │ │ │ -08B7E   Flags               03 (3) 'Modification Access'
│ │ │ │ -08B7F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -08B83   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -08B87 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -08B89   Length              000B (11)
│ │ │ │ -08B8B   Version             01 (1)
│ │ │ │ -08B8C   UID Size            04 (4)
│ │ │ │ -08B8D   UID                 00000000 (0)
│ │ │ │ -08B91   GID Size            04 (4)
│ │ │ │ -08B92   GID                 00000000 (0)
│ │ │ │ -08B96 PAYLOAD
│ │ │ │ -
│ │ │ │ -0C415 LOCAL HEADER #11      04034B50 (67324752)
│ │ │ │ -0C419 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -0C41A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -0C41B General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -0C41D Compression Method    0008 (8) 'Deflated'
│ │ │ │ -0C41F Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -0C423 CRC                   2368599F (594041247)
│ │ │ │ -0C427 Compressed Size       0000AAD3 (43731)
│ │ │ │ -0C42B Uncompressed Size     0003DFDE (253918)
│ │ │ │ -0C42F Filename Length       0012 (18)
│ │ │ │ -0C431 Extra Length          001C (28)
│ │ │ │ -0C433 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0xC433: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -0C445 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -0C447   Length              0009 (9)
│ │ │ │ -0C449   Flags               03 (3) 'Modification Access'
│ │ │ │ -0C44A   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -0C44E   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -0C452 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -0C454   Length              000B (11)
│ │ │ │ -0C456   Version             01 (1)
│ │ │ │ -0C457   UID Size            04 (4)
│ │ │ │ -0C458   UID                 00000000 (0)
│ │ │ │ -0C45C   GID Size            04 (4)
│ │ │ │ -0C45D   GID                 00000000 (0)
│ │ │ │ -0C461 PAYLOAD
│ │ │ │ -
│ │ │ │ -16F34 LOCAL HEADER #12      04034B50 (67324752)
│ │ │ │ -16F38 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -16F39 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -16F3A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -16F3C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -16F3E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -16F42 CRC                   2DEC84BF (770475199)
│ │ │ │ -16F46 Compressed Size       00003B1E (15134)
│ │ │ │ -16F4A Uncompressed Size     0001B2A0 (111264)
│ │ │ │ -16F4E Filename Length       0015 (21)
│ │ │ │ -16F50 Extra Length          001C (28)
│ │ │ │ -16F52 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x16F52: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -16F67 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -16F69   Length              0009 (9)
│ │ │ │ -16F6B   Flags               03 (3) 'Modification Access'
│ │ │ │ -16F6C   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -16F70   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -16F74 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -16F76   Length              000B (11)
│ │ │ │ -16F78   Version             01 (1)
│ │ │ │ -16F79   UID Size            04 (4)
│ │ │ │ -16F7A   UID                 00000000 (0)
│ │ │ │ -16F7E   GID Size            04 (4)
│ │ │ │ -16F7F   GID                 00000000 (0)
│ │ │ │ -16F83 PAYLOAD
│ │ │ │ -
│ │ │ │ -1AAA1 LOCAL HEADER #13      04034B50 (67324752)
│ │ │ │ -1AAA5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -1AAA6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -1AAA7 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -1AAA9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -1AAAB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -1AAAF CRC                   352F19D3 (892279251)
│ │ │ │ -1AAB3 Compressed Size       00009090 (37008)
│ │ │ │ -1AAB7 Uncompressed Size     0003D05F (249951)
│ │ │ │ -1AABB Filename Length       0014 (20)
│ │ │ │ -1AABD Extra Length          001C (28)
│ │ │ │ -1AABF Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x1AABF: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -1AAD3 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -1AAD5   Length              0009 (9)
│ │ │ │ -1AAD7   Flags               03 (3) 'Modification Access'
│ │ │ │ -1AAD8   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -1AADC   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -1AAE0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -1AAE2   Length              000B (11)
│ │ │ │ -1AAE4   Version             01 (1)
│ │ │ │ -1AAE5   UID Size            04 (4)
│ │ │ │ -1AAE6   UID                 00000000 (0)
│ │ │ │ -1AAEA   GID Size            04 (4)
│ │ │ │ -1AAEB   GID                 00000000 (0)
│ │ │ │ -1AAEF PAYLOAD
│ │ │ │ -
│ │ │ │ -23B7F LOCAL HEADER #14      04034B50 (67324752)
│ │ │ │ -23B83 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -23B84 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -23B85 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -23B87 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -23B89 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -23B8D CRC                   A14752A3 (2705805987)
│ │ │ │ -23B91 Compressed Size       00002A65 (10853)
│ │ │ │ -23B95 Uncompressed Size     0001151F (70943)
│ │ │ │ -23B99 Filename Length       0016 (22)
│ │ │ │ -23B9B Extra Length          001C (28)
│ │ │ │ -23B9D Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x23B9D: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -23BB3 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -23BB5   Length              0009 (9)
│ │ │ │ -23BB7   Flags               03 (3) 'Modification Access'
│ │ │ │ -23BB8   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -23BBC   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -23BC0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -23BC2   Length              000B (11)
│ │ │ │ -23BC4   Version             01 (1)
│ │ │ │ -23BC5   UID Size            04 (4)
│ │ │ │ -23BC6   UID                 00000000 (0)
│ │ │ │ -23BCA   GID Size            04 (4)
│ │ │ │ -23BCB   GID                 00000000 (0)
│ │ │ │ -23BCF PAYLOAD
│ │ │ │ -
│ │ │ │ -26634 LOCAL HEADER #15      04034B50 (67324752)
│ │ │ │ -26638 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -26639 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -2663A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -2663C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -2663E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -26642 CRC                   F1E18143 (4058087747)
│ │ │ │ -26646 Compressed Size       000014D8 (5336)
│ │ │ │ -2664A Uncompressed Size     00005176 (20854)
│ │ │ │ -2664E Filename Length       001D (29)
│ │ │ │ -26650 Extra Length          001C (28)
│ │ │ │ -26652 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x26652: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -2666F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -26671   Length              0009 (9)
│ │ │ │ -26673   Flags               03 (3) 'Modification Access'
│ │ │ │ -26674   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -26678   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2667C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -2667E   Length              000B (11)
│ │ │ │ -26680   Version             01 (1)
│ │ │ │ -26681   UID Size            04 (4)
│ │ │ │ -26682   UID                 00000000 (0)
│ │ │ │ -26686   GID Size            04 (4)
│ │ │ │ -26687   GID                 00000000 (0)
│ │ │ │ -2668B PAYLOAD
│ │ │ │ -
│ │ │ │ -27B63 LOCAL HEADER #16      04034B50 (67324752)
│ │ │ │ -27B67 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -27B68 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -27B69 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -27B6B Compression Method    0008 (8) 'Deflated'
│ │ │ │ -27B6D Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -27B71 CRC                   78898277 (2022277751)
│ │ │ │ -27B75 Compressed Size       000037F6 (14326)
│ │ │ │ -27B79 Uncompressed Size     0000E9F0 (59888)
│ │ │ │ -27B7D Filename Length       001C (28)
│ │ │ │ -27B7F Extra Length          001C (28)
│ │ │ │ -27B81 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x27B81: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -27B9D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -27B9F   Length              0009 (9)
│ │ │ │ -27BA1   Flags               03 (3) 'Modification Access'
│ │ │ │ -27BA2   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -27BA6   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -27BAA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -27BAC   Length              000B (11)
│ │ │ │ -27BAE   Version             01 (1)
│ │ │ │ -27BAF   UID Size            04 (4)
│ │ │ │ -27BB0   UID                 00000000 (0)
│ │ │ │ -27BB4   GID Size            04 (4)
│ │ │ │ -27BB5   GID                 00000000 (0)
│ │ │ │ -27BB9 PAYLOAD
│ │ │ │ -
│ │ │ │ -2B3AF LOCAL HEADER #17      04034B50 (67324752)
│ │ │ │ -2B3B3 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -2B3B4 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -2B3B5 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -2B3B7 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -2B3B9 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -2B3BD CRC                   6A63C5E7 (1784923623)
│ │ │ │ -2B3C1 Compressed Size       000006A0 (1696)
│ │ │ │ -2B3C5 Uncompressed Size     000011F4 (4596)
│ │ │ │ -2B3C9 Filename Length       001C (28)
│ │ │ │ -2B3CB Extra Length          001C (28)
│ │ │ │ -2B3CD Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x2B3CD: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -2B3E9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -2B3EB   Length              0009 (9)
│ │ │ │ -2B3ED   Flags               03 (3) 'Modification Access'
│ │ │ │ -2B3EE   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2B3F2   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2B3F6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -2B3F8   Length              000B (11)
│ │ │ │ -2B3FA   Version             01 (1)
│ │ │ │ -2B3FB   UID Size            04 (4)
│ │ │ │ -2B3FC   UID                 00000000 (0)
│ │ │ │ -2B400   GID Size            04 (4)
│ │ │ │ -2B401   GID                 00000000 (0)
│ │ │ │ -2B405 PAYLOAD
│ │ │ │ -
│ │ │ │ -2BAA5 LOCAL HEADER #18      04034B50 (67324752)
│ │ │ │ -2BAA9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -2BAAA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -2BAAB General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -2BAAD Compression Method    0008 (8) 'Deflated'
│ │ │ │ -2BAAF Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -2BAB3 CRC                   4B420ADA (1262619354)
│ │ │ │ -2BAB7 Compressed Size       0000107B (4219)
│ │ │ │ -2BABB Uncompressed Size     00004BFF (19455)
│ │ │ │ -2BABF Filename Length       001B (27)
│ │ │ │ -2BAC1 Extra Length          001C (28)
│ │ │ │ -2BAC3 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x2BAC3: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -2BADE Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -2BAE0   Length              0009 (9)
│ │ │ │ -2BAE2   Flags               03 (3) 'Modification Access'
│ │ │ │ -2BAE3   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2BAE7   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2BAEB Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -2BAED   Length              000B (11)
│ │ │ │ -2BAEF   Version             01 (1)
│ │ │ │ -2BAF0   UID Size            04 (4)
│ │ │ │ -2BAF1   UID                 00000000 (0)
│ │ │ │ -2BAF5   GID Size            04 (4)
│ │ │ │ -2BAF6   GID                 00000000 (0)
│ │ │ │ -2BAFA PAYLOAD
│ │ │ │ -
│ │ │ │ -2CB75 LOCAL HEADER #19      04034B50 (67324752)
│ │ │ │ -2CB79 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -2CB7A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -2CB7B General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -2CB7D Compression Method    0008 (8) 'Deflated'
│ │ │ │ -2CB7F Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -2CB83 CRC                   A579921F (2776207903)
│ │ │ │ -2CB87 Compressed Size       000033AB (13227)
│ │ │ │ -2CB8B Uncompressed Size     0000BC94 (48276)
│ │ │ │ -2CB8F Filename Length       001D (29)
│ │ │ │ -2CB91 Extra Length          001C (28)
│ │ │ │ -2CB93 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x2CB93: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -2CBB0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -2CBB2   Length              0009 (9)
│ │ │ │ -2CBB4   Flags               03 (3) 'Modification Access'
│ │ │ │ -2CBB5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2CBB9   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2CBBD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -2CBBF   Length              000B (11)
│ │ │ │ -2CBC1   Version             01 (1)
│ │ │ │ -2CBC2   UID Size            04 (4)
│ │ │ │ -2CBC3   UID                 00000000 (0)
│ │ │ │ -2CBC7   GID Size            04 (4)
│ │ │ │ -2CBC8   GID                 00000000 (0)
│ │ │ │ -2CBCC PAYLOAD
│ │ │ │ -
│ │ │ │ -2FF77 LOCAL HEADER #20      04034B50 (67324752)
│ │ │ │ -2FF7B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -2FF7C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -2FF7D General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -2FF7F Compression Method    0008 (8) 'Deflated'
│ │ │ │ -2FF81 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -2FF85 CRC                   3BBA297E (1002056062)
│ │ │ │ -2FF89 Compressed Size       00000D6C (3436)
│ │ │ │ -2FF8D Uncompressed Size     00003876 (14454)
│ │ │ │ -2FF91 Filename Length       001D (29)
│ │ │ │ -2FF93 Extra Length          001C (28)
│ │ │ │ -2FF95 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x2FF95: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -2FFB2 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -2FFB4   Length              0009 (9)
│ │ │ │ -2FFB6   Flags               03 (3) 'Modification Access'
│ │ │ │ -2FFB7   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2FFBB   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -2FFBF Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -2FFC1   Length              000B (11)
│ │ │ │ -2FFC3   Version             01 (1)
│ │ │ │ -2FFC4   UID Size            04 (4)
│ │ │ │ -2FFC5   UID                 00000000 (0)
│ │ │ │ -2FFC9   GID Size            04 (4)
│ │ │ │ -2FFCA   GID                 00000000 (0)
│ │ │ │ -2FFCE PAYLOAD
│ │ │ │ -
│ │ │ │ -30D3A LOCAL HEADER #21      04034B50 (67324752)
│ │ │ │ -30D3E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -30D3F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -30D40 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -30D42 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -30D44 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -30D48 CRC                   CE4502E0 (3460629216)
│ │ │ │ -30D4C Compressed Size       00001C6A (7274)
│ │ │ │ -30D50 Uncompressed Size     0000C186 (49542)
│ │ │ │ -30D54 Filename Length       001A (26)
│ │ │ │ -30D56 Extra Length          001C (28)
│ │ │ │ -30D58 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x30D58: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -30D72 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -30D74   Length              0009 (9)
│ │ │ │ -30D76   Flags               03 (3) 'Modification Access'
│ │ │ │ -30D77   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -30D7B   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -30D7F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -30D81   Length              000B (11)
│ │ │ │ -30D83   Version             01 (1)
│ │ │ │ -30D84   UID Size            04 (4)
│ │ │ │ -30D85   UID                 00000000 (0)
│ │ │ │ -30D89   GID Size            04 (4)
│ │ │ │ -30D8A   GID                 00000000 (0)
│ │ │ │ -30D8E PAYLOAD
│ │ │ │ -
│ │ │ │ -329F8 LOCAL HEADER #22      04034B50 (67324752)
│ │ │ │ -329FC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -329FD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -329FE General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -32A00 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -32A02 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -32A06 CRC                   65574916 (1700219158)
│ │ │ │ -32A0A Compressed Size       000003A3 (931)
│ │ │ │ -32A0E Uncompressed Size     0000088E (2190)
│ │ │ │ -32A12 Filename Length       0012 (18)
│ │ │ │ -32A14 Extra Length          001C (28)
│ │ │ │ -32A16 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x32A16: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -32A28 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -32A2A   Length              0009 (9)
│ │ │ │ -32A2C   Flags               03 (3) 'Modification Access'
│ │ │ │ -32A2D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -32A31   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -32A35 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -32A37   Length              000B (11)
│ │ │ │ -32A39   Version             01 (1)
│ │ │ │ -32A3A   UID Size            04 (4)
│ │ │ │ -32A3B   UID                 00000000 (0)
│ │ │ │ -32A3F   GID Size            04 (4)
│ │ │ │ -32A40   GID                 00000000 (0)
│ │ │ │ -32A44 PAYLOAD
│ │ │ │ -
│ │ │ │ -32DE7 LOCAL HEADER #23      04034B50 (67324752)
│ │ │ │ -32DEB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -32DEC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -32DED General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -32DEF Compression Method    0008 (8) 'Deflated'
│ │ │ │ -32DF1 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -32DF5 CRC                   83472134 (2202476852)
│ │ │ │ -32DF9 Compressed Size       000001D4 (468)
│ │ │ │ -32DFD Uncompressed Size     00000311 (785)
│ │ │ │ -32E01 Filename Length       0020 (32)
│ │ │ │ -32E03 Extra Length          001C (28)
│ │ │ │ -32E05 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x32E05: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -32E25 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -32E27   Length              0009 (9)
│ │ │ │ -32E29   Flags               03 (3) 'Modification Access'
│ │ │ │ -32E2A   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -32E2E   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -32E32 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -32E34   Length              000B (11)
│ │ │ │ -32E36   Version             01 (1)
│ │ │ │ -32E37   UID Size            04 (4)
│ │ │ │ -32E38   UID                 00000000 (0)
│ │ │ │ -32E3C   GID Size            04 (4)
│ │ │ │ -32E3D   GID                 00000000 (0)
│ │ │ │ -32E41 PAYLOAD
│ │ │ │ -
│ │ │ │ -33015 LOCAL HEADER #24      04034B50 (67324752)
│ │ │ │ -33019 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -3301A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -3301B General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -3301D Compression Method    0008 (8) 'Deflated'
│ │ │ │ -3301F Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -33023 CRC                   E5289043 (3844640835)
│ │ │ │ -33027 Compressed Size       000017A7 (6055)
│ │ │ │ -3302B Uncompressed Size     00009CD3 (40147)
│ │ │ │ -3302F Filename Length       001B (27)
│ │ │ │ -33031 Extra Length          001C (28)
│ │ │ │ -33033 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x33033: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3304E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -33050   Length              0009 (9)
│ │ │ │ -33052   Flags               03 (3) 'Modification Access'
│ │ │ │ -33053   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -33057   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3305B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3305D   Length              000B (11)
│ │ │ │ -3305F   Version             01 (1)
│ │ │ │ -33060   UID Size            04 (4)
│ │ │ │ -33061   UID                 00000000 (0)
│ │ │ │ -33065   GID Size            04 (4)
│ │ │ │ -33066   GID                 00000000 (0)
│ │ │ │ -3306A PAYLOAD
│ │ │ │ -
│ │ │ │ -34811 LOCAL HEADER #25      04034B50 (67324752)
│ │ │ │ -34815 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -34816 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -34817 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -34819 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -3481B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -3481F CRC                   5F73B5AE (1601418670)
│ │ │ │ -34823 Compressed Size       00001371 (4977)
│ │ │ │ -34827 Uncompressed Size     00003B66 (15206)
│ │ │ │ -3482B Filename Length       0015 (21)
│ │ │ │ -3482D Extra Length          001C (28)
│ │ │ │ -3482F Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3482F: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -34844 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -34846   Length              0009 (9)
│ │ │ │ -34848   Flags               03 (3) 'Modification Access'
│ │ │ │ -34849   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3484D   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -34851 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -34853   Length              000B (11)
│ │ │ │ -34855   Version             01 (1)
│ │ │ │ -34856   UID Size            04 (4)
│ │ │ │ -34857   UID                 00000000 (0)
│ │ │ │ -3485B   GID Size            04 (4)
│ │ │ │ -3485C   GID                 00000000 (0)
│ │ │ │ -34860 PAYLOAD
│ │ │ │ -
│ │ │ │ -35BD1 LOCAL HEADER #26      04034B50 (67324752)
│ │ │ │ -35BD5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -35BD6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -35BD7 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -35BD9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -35BDB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -35BDF CRC                   7FAE09B6 (2142112182)
│ │ │ │ -35BE3 Compressed Size       00000AD1 (2769)
│ │ │ │ -35BE7 Uncompressed Size     00002135 (8501)
│ │ │ │ -35BEB Filename Length       0011 (17)
│ │ │ │ -35BED Extra Length          001C (28)
│ │ │ │ -35BEF Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x35BEF: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -35C00 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -35C02   Length              0009 (9)
│ │ │ │ -35C04   Flags               03 (3) 'Modification Access'
│ │ │ │ -35C05   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -35C09   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -35C0D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -35C0F   Length              000B (11)
│ │ │ │ -35C11   Version             01 (1)
│ │ │ │ -35C12   UID Size            04 (4)
│ │ │ │ -35C13   UID                 00000000 (0)
│ │ │ │ -35C17   GID Size            04 (4)
│ │ │ │ -35C18   GID                 00000000 (0)
│ │ │ │ -35C1C PAYLOAD
│ │ │ │ -
│ │ │ │ -366ED LOCAL HEADER #27      04034B50 (67324752)
│ │ │ │ -366F1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -366F2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -366F3 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -366F5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -366F7 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -366FB CRC                   F2F690A2 (4076245154)
│ │ │ │ -366FF Compressed Size       000003FE (1022)
│ │ │ │ -36703 Uncompressed Size     00000E99 (3737)
│ │ │ │ -36707 Filename Length       0014 (20)
│ │ │ │ -36709 Extra Length          001C (28)
│ │ │ │ -3670B Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3670B: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3671F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -36721   Length              0009 (9)
│ │ │ │ -36723   Flags               03 (3) 'Modification Access'
│ │ │ │ -36724   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -36728   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3672C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3672E   Length              000B (11)
│ │ │ │ -36730   Version             01 (1)
│ │ │ │ -36731   UID Size            04 (4)
│ │ │ │ -36732   UID                 00000000 (0)
│ │ │ │ -36736   GID Size            04 (4)
│ │ │ │ -36737   GID                 00000000 (0)
│ │ │ │ -3673B PAYLOAD
│ │ │ │ -
│ │ │ │ -36B39 LOCAL HEADER #28      04034B50 (67324752)
│ │ │ │ -36B3D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -36B3E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -36B3F General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -36B41 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -36B43 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -36B47 CRC                   EB83ACB7 (3951275191)
│ │ │ │ -36B4B Compressed Size       00001261 (4705)
│ │ │ │ -36B4F Uncompressed Size     00003469 (13417)
│ │ │ │ -36B53 Filename Length       0014 (20)
│ │ │ │ -36B55 Extra Length          001C (28)
│ │ │ │ -36B57 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x36B57: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -36B6B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -36B6D   Length              0009 (9)
│ │ │ │ -36B6F   Flags               03 (3) 'Modification Access'
│ │ │ │ -36B70   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -36B74   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -36B78 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -36B7A   Length              000B (11)
│ │ │ │ -36B7C   Version             01 (1)
│ │ │ │ -36B7D   UID Size            04 (4)
│ │ │ │ -36B7E   UID                 00000000 (0)
│ │ │ │ -36B82   GID Size            04 (4)
│ │ │ │ -36B83   GID                 00000000 (0)
│ │ │ │ -36B87 PAYLOAD
│ │ │ │ -
│ │ │ │ -37DE8 LOCAL HEADER #29      04034B50 (67324752)
│ │ │ │ -37DEC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -37DED Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -37DEE General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -37DF0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -37DF2 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -37DF6 CRC                   ED6E01D4 (3983409620)
│ │ │ │ -37DFA Compressed Size       00000AD0 (2768)
│ │ │ │ -37DFE Uncompressed Size     000022FF (8959)
│ │ │ │ -37E02 Filename Length       001B (27)
│ │ │ │ -37E04 Extra Length          001C (28)
│ │ │ │ -37E06 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x37E06: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -37E21 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -37E23   Length              0009 (9)
│ │ │ │ -37E25   Flags               03 (3) 'Modification Access'
│ │ │ │ -37E26   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -37E2A   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -37E2E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -37E30   Length              000B (11)
│ │ │ │ -37E32   Version             01 (1)
│ │ │ │ -37E33   UID Size            04 (4)
│ │ │ │ -37E34   UID                 00000000 (0)
│ │ │ │ -37E38   GID Size            04 (4)
│ │ │ │ -37E39   GID                 00000000 (0)
│ │ │ │ -37E3D PAYLOAD
│ │ │ │ -
│ │ │ │ -3890D LOCAL HEADER #30      04034B50 (67324752)
│ │ │ │ -38911 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -38912 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -38913 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -38915 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -38917 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -3891B CRC                   7FE9699A (2146003354)
│ │ │ │ -3891F Compressed Size       00000A8D (2701)
│ │ │ │ -38923 Uncompressed Size     0000237A (9082)
│ │ │ │ -38927 Filename Length       0013 (19)
│ │ │ │ -38929 Extra Length          001C (28)
│ │ │ │ -3892B Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3892B: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3893E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -38940   Length              0009 (9)
│ │ │ │ -38942   Flags               03 (3) 'Modification Access'
│ │ │ │ -38943   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -38947   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3894B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3894D   Length              000B (11)
│ │ │ │ -3894F   Version             01 (1)
│ │ │ │ -38950   UID Size            04 (4)
│ │ │ │ -38951   UID                 00000000 (0)
│ │ │ │ -38955   GID Size            04 (4)
│ │ │ │ -38956   GID                 00000000 (0)
│ │ │ │ -3895A PAYLOAD
│ │ │ │ -
│ │ │ │ -393E7 LOCAL HEADER #31      04034B50 (67324752)
│ │ │ │ -393EB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -393EC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -393ED General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -393EF Compression Method    0008 (8) 'Deflated'
│ │ │ │ -393F1 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -393F5 CRC                   DD9D1818 (3718060056)
│ │ │ │ -393F9 Compressed Size       00000F48 (3912)
│ │ │ │ -393FD Uncompressed Size     000036F1 (14065)
│ │ │ │ -39401 Filename Length       000F (15)
│ │ │ │ -39403 Extra Length          001C (28)
│ │ │ │ -39405 Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x39405: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -39414 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -39416   Length              0009 (9)
│ │ │ │ -39418   Flags               03 (3) 'Modification Access'
│ │ │ │ -39419   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3941D   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -39421 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -39423   Length              000B (11)
│ │ │ │ -39425   Version             01 (1)
│ │ │ │ -39426   UID Size            04 (4)
│ │ │ │ -39427   UID                 00000000 (0)
│ │ │ │ -3942B   GID Size            04 (4)
│ │ │ │ -3942C   GID                 00000000 (0)
│ │ │ │ -39430 PAYLOAD
│ │ │ │ -
│ │ │ │ -3A378 LOCAL HEADER #32      04034B50 (67324752)
│ │ │ │ -3A37C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -3A37D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -3A37E General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -3A380 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -3A382 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -3A386 CRC                   54672E6E (1416048238)
│ │ │ │ -3A38A Compressed Size       0000066A (1642)
│ │ │ │ -3A38E Uncompressed Size     000018DF (6367)
│ │ │ │ -3A392 Filename Length       000F (15)
│ │ │ │ -3A394 Extra Length          001C (28)
│ │ │ │ -3A396 Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3A396: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3A3A5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -3A3A7   Length              0009 (9)
│ │ │ │ -3A3A9   Flags               03 (3) 'Modification Access'
│ │ │ │ -3A3AA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3A3AE   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3A3B2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3A3B4   Length              000B (11)
│ │ │ │ -3A3B6   Version             01 (1)
│ │ │ │ -3A3B7   UID Size            04 (4)
│ │ │ │ -3A3B8   UID                 00000000 (0)
│ │ │ │ -3A3BC   GID Size            04 (4)
│ │ │ │ -3A3BD   GID                 00000000 (0)
│ │ │ │ -3A3C1 PAYLOAD
│ │ │ │ -
│ │ │ │ -3AA2B LOCAL HEADER #33      04034B50 (67324752)
│ │ │ │ -3AA2F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -3AA30 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -3AA31 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -3AA33 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -3AA35 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -3AA39 CRC                   8AF71E36 (2331450934)
│ │ │ │ -3AA3D Compressed Size       00001A49 (6729)
│ │ │ │ -3AA41 Uncompressed Size     000064F2 (25842)
│ │ │ │ -3AA45 Filename Length       0013 (19)
│ │ │ │ -3AA47 Extra Length          001C (28)
│ │ │ │ -3AA49 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3AA49: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3AA5C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -3AA5E   Length              0009 (9)
│ │ │ │ -3AA60   Flags               03 (3) 'Modification Access'
│ │ │ │ -3AA61   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3AA65   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3AA69 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3AA6B   Length              000B (11)
│ │ │ │ -3AA6D   Version             01 (1)
│ │ │ │ -3AA6E   UID Size            04 (4)
│ │ │ │ -3AA6F   UID                 00000000 (0)
│ │ │ │ -3AA73   GID Size            04 (4)
│ │ │ │ -3AA74   GID                 00000000 (0)
│ │ │ │ -3AA78 PAYLOAD
│ │ │ │ -
│ │ │ │ -3C4C1 LOCAL HEADER #34      04034B50 (67324752)
│ │ │ │ -3C4C5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -3C4C6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -3C4C7 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -3C4C9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -3C4CB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -3C4CF CRC                   D1448544 (3510928708)
│ │ │ │ -3C4D3 Compressed Size       000009A5 (2469)
│ │ │ │ -3C4D7 Uncompressed Size     00001B64 (7012)
│ │ │ │ -3C4DB Filename Length       0010 (16)
│ │ │ │ -3C4DD Extra Length          001C (28)
│ │ │ │ -3C4DF Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3C4DF: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3C4EF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -3C4F1   Length              0009 (9)
│ │ │ │ -3C4F3   Flags               03 (3) 'Modification Access'
│ │ │ │ -3C4F4   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3C4F8   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3C4FC Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3C4FE   Length              000B (11)
│ │ │ │ -3C500   Version             01 (1)
│ │ │ │ -3C501   UID Size            04 (4)
│ │ │ │ -3C502   UID                 00000000 (0)
│ │ │ │ -3C506   GID Size            04 (4)
│ │ │ │ -3C507   GID                 00000000 (0)
│ │ │ │ -3C50B PAYLOAD
│ │ │ │ -
│ │ │ │ -3CEB0 LOCAL HEADER #35      04034B50 (67324752)
│ │ │ │ -3CEB4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -3CEB5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -3CEB6 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -3CEB8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -3CEBA Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -3CEBE CRC                   3E5AEB62 (1046145890)
│ │ │ │ -3CEC2 Compressed Size       000006B7 (1719)
│ │ │ │ -3CEC6 Uncompressed Size     00001565 (5477)
│ │ │ │ -3CECA Filename Length       0012 (18)
│ │ │ │ -3CECC Extra Length          001C (28)
│ │ │ │ -3CECE Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3CECE: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3CEE0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -3CEE2   Length              0009 (9)
│ │ │ │ -3CEE4   Flags               03 (3) 'Modification Access'
│ │ │ │ -3CEE5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3CEE9   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3CEED Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3CEEF   Length              000B (11)
│ │ │ │ -3CEF1   Version             01 (1)
│ │ │ │ -3CEF2   UID Size            04 (4)
│ │ │ │ -3CEF3   UID                 00000000 (0)
│ │ │ │ -3CEF7   GID Size            04 (4)
│ │ │ │ -3CEF8   GID                 00000000 (0)
│ │ │ │ -3CEFC PAYLOAD
│ │ │ │ -
│ │ │ │ -3D5B3 LOCAL HEADER #36      04034B50 (67324752)
│ │ │ │ -3D5B7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -3D5B8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -3D5B9 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -3D5BB Compression Method    0008 (8) 'Deflated'
│ │ │ │ -3D5BD Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -3D5C1 CRC                   C50CE88C (3305957516)
│ │ │ │ -3D5C5 Compressed Size       00002A1A (10778)
│ │ │ │ -3D5C9 Uncompressed Size     0000B1C5 (45509)
│ │ │ │ -3D5CD Filename Length       0010 (16)
│ │ │ │ -3D5CF Extra Length          001C (28)
│ │ │ │ -3D5D1 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x3D5D1: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -3D5E1 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -3D5E3   Length              0009 (9)
│ │ │ │ -3D5E5   Flags               03 (3) 'Modification Access'
│ │ │ │ -3D5E6   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3D5EA   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -3D5EE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -3D5F0   Length              000B (11)
│ │ │ │ -3D5F2   Version             01 (1)
│ │ │ │ -3D5F3   UID Size            04 (4)
│ │ │ │ -3D5F4   UID                 00000000 (0)
│ │ │ │ -3D5F8   GID Size            04 (4)
│ │ │ │ -3D5F9   GID                 00000000 (0)
│ │ │ │ -3D5FD PAYLOAD
│ │ │ │ -
│ │ │ │ -40017 LOCAL HEADER #37      04034B50 (67324752)
│ │ │ │ -4001B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -4001C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -4001D General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -4001F Compression Method    0008 (8) 'Deflated'
│ │ │ │ -40021 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -40025 CRC                   C59A1802 (3315210242)
│ │ │ │ -40029 Compressed Size       00001E84 (7812)
│ │ │ │ -4002D Uncompressed Size     00009AAA (39594)
│ │ │ │ -40031 Filename Length       0012 (18)
│ │ │ │ -40033 Extra Length          001C (28)
│ │ │ │ -40035 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x40035: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -40047 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -40049   Length              0009 (9)
│ │ │ │ -4004B   Flags               03 (3) 'Modification Access'
│ │ │ │ -4004C   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -40050   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -40054 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -40056   Length              000B (11)
│ │ │ │ -40058   Version             01 (1)
│ │ │ │ -40059   UID Size            04 (4)
│ │ │ │ -4005A   UID                 00000000 (0)
│ │ │ │ -4005E   GID Size            04 (4)
│ │ │ │ -4005F   GID                 00000000 (0)
│ │ │ │ -40063 PAYLOAD
│ │ │ │ -
│ │ │ │ -41EE7 LOCAL HEADER #38      04034B50 (67324752)
│ │ │ │ -41EEB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -41EEC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -41EED General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -41EEF Compression Method    0008 (8) 'Deflated'
│ │ │ │ -41EF1 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -41EF5 CRC                   A34909C0 (2739472832)
│ │ │ │ -41EF9 Compressed Size       00001477 (5239)
│ │ │ │ -41EFD Uncompressed Size     00007ACF (31439)
│ │ │ │ -41F01 Filename Length       0018 (24)
│ │ │ │ -41F03 Extra Length          001C (28)
│ │ │ │ -41F05 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x41F05: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -41F1D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -41F1F   Length              0009 (9)
│ │ │ │ -41F21   Flags               03 (3) 'Modification Access'
│ │ │ │ -41F22   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -41F26   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -41F2A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -41F2C   Length              000B (11)
│ │ │ │ -41F2E   Version             01 (1)
│ │ │ │ -41F2F   UID Size            04 (4)
│ │ │ │ -41F30   UID                 00000000 (0)
│ │ │ │ -41F34   GID Size            04 (4)
│ │ │ │ -41F35   GID                 00000000 (0)
│ │ │ │ -41F39 PAYLOAD
│ │ │ │ -
│ │ │ │ -433B0 LOCAL HEADER #39      04034B50 (67324752)
│ │ │ │ -433B4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -433B5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -433B6 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -433B8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -433BA Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -433BE CRC                   C605A326 (3322258214)
│ │ │ │ -433C2 Compressed Size       000018CF (6351)
│ │ │ │ -433C6 Uncompressed Size     0000A7F4 (42996)
│ │ │ │ -433CA Filename Length       001F (31)
│ │ │ │ -433CC Extra Length          001C (28)
│ │ │ │ -433CE Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x433CE: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -433ED Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -433EF   Length              0009 (9)
│ │ │ │ -433F1   Flags               03 (3) 'Modification Access'
│ │ │ │ -433F2   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -433F6   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -433FA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -433FC   Length              000B (11)
│ │ │ │ -433FE   Version             01 (1)
│ │ │ │ -433FF   UID Size            04 (4)
│ │ │ │ -43400   UID                 00000000 (0)
│ │ │ │ -43404   GID Size            04 (4)
│ │ │ │ -43405   GID                 00000000 (0)
│ │ │ │ -43409 PAYLOAD
│ │ │ │ -
│ │ │ │ -44CD8 LOCAL HEADER #40      04034B50 (67324752)
│ │ │ │ -44CDC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -44CDD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -44CDE General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -44CE0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -44CE2 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -44CE6 CRC                   FFAF198F (4289665423)
│ │ │ │ -44CEA Compressed Size       000003F6 (1014)
│ │ │ │ -44CEE Uncompressed Size     000008A3 (2211)
│ │ │ │ -44CF2 Filename Length       001E (30)
│ │ │ │ -44CF4 Extra Length          001C (28)
│ │ │ │ -44CF6 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x44CF6: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -44D14 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -44D16   Length              0009 (9)
│ │ │ │ -44D18   Flags               03 (3) 'Modification Access'
│ │ │ │ -44D19   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -44D1D   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -44D21 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -44D23   Length              000B (11)
│ │ │ │ -44D25   Version             01 (1)
│ │ │ │ -44D26   UID Size            04 (4)
│ │ │ │ -44D27   UID                 00000000 (0)
│ │ │ │ -44D2B   GID Size            04 (4)
│ │ │ │ -44D2C   GID                 00000000 (0)
│ │ │ │ -44D30 PAYLOAD
│ │ │ │ -
│ │ │ │ -45126 LOCAL HEADER #41      04034B50 (67324752)
│ │ │ │ -4512A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -4512B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -4512C General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -4512E Compression Method    0008 (8) 'Deflated'
│ │ │ │ -45130 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -45134 CRC                   32E3FA13 (853801491)
│ │ │ │ -45138 Compressed Size       00004292 (17042)
│ │ │ │ -4513C Uncompressed Size     0000D8DC (55516)
│ │ │ │ -45140 Filename Length       0013 (19)
│ │ │ │ -45142 Extra Length          001C (28)
│ │ │ │ -45144 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x45144: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -45157 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -45159   Length              0009 (9)
│ │ │ │ -4515B   Flags               03 (3) 'Modification Access'
│ │ │ │ -4515C   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -45160   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -45164 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -45166   Length              000B (11)
│ │ │ │ -45168   Version             01 (1)
│ │ │ │ -45169   UID Size            04 (4)
│ │ │ │ -4516A   UID                 00000000 (0)
│ │ │ │ -4516E   GID Size            04 (4)
│ │ │ │ -4516F   GID                 00000000 (0)
│ │ │ │ -45173 PAYLOAD
│ │ │ │ -
│ │ │ │ -49405 LOCAL HEADER #42      04034B50 (67324752)
│ │ │ │ -49409 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -4940A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -4940B General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -4940D Compression Method    0008 (8) 'Deflated'
│ │ │ │ -4940F Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -49413 CRC                   9F6AFEBF (2674589375)
│ │ │ │ -49417 Compressed Size       000026C3 (9923)
│ │ │ │ -4941B Uncompressed Size     00006E45 (28229)
│ │ │ │ -4941F Filename Length       0019 (25)
│ │ │ │ -49421 Extra Length          001C (28)
│ │ │ │ -49423 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x49423: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -4943C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -4943E   Length              0009 (9)
│ │ │ │ -49440   Flags               03 (3) 'Modification Access'
│ │ │ │ -49441   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -49445   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -49449 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -4944B   Length              000B (11)
│ │ │ │ -4944D   Version             01 (1)
│ │ │ │ -4944E   UID Size            04 (4)
│ │ │ │ -4944F   UID                 00000000 (0)
│ │ │ │ -49453   GID Size            04 (4)
│ │ │ │ -49454   GID                 00000000 (0)
│ │ │ │ -49458 PAYLOAD
│ │ │ │ -
│ │ │ │ -4BB1B LOCAL HEADER #43      04034B50 (67324752)
│ │ │ │ -4BB1F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -4BB20 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -4BB21 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -4BB23 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -4BB25 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -4BB29 CRC                   0369577C (57235324)
│ │ │ │ -4BB2D Compressed Size       00002739 (10041)
│ │ │ │ -4BB31 Uncompressed Size     00008B83 (35715)
│ │ │ │ -4BB35 Filename Length       0019 (25)
│ │ │ │ -4BB37 Extra Length          001C (28)
│ │ │ │ -4BB39 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x4BB39: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -4BB52 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -4BB54   Length              0009 (9)
│ │ │ │ -4BB56   Flags               03 (3) 'Modification Access'
│ │ │ │ -4BB57   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4BB5B   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4BB5F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -4BB61   Length              000B (11)
│ │ │ │ -4BB63   Version             01 (1)
│ │ │ │ -4BB64   UID Size            04 (4)
│ │ │ │ -4BB65   UID                 00000000 (0)
│ │ │ │ -4BB69   GID Size            04 (4)
│ │ │ │ -4BB6A   GID                 00000000 (0)
│ │ │ │ -4BB6E PAYLOAD
│ │ │ │ -
│ │ │ │ -4E2A7 LOCAL HEADER #44      04034B50 (67324752)
│ │ │ │ -4E2AB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -4E2AC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -4E2AD General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -4E2AF Compression Method    0008 (8) 'Deflated'
│ │ │ │ -4E2B1 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -4E2B5 CRC                   8B9BB6EF (2342237935)
│ │ │ │ -4E2B9 Compressed Size       00000CF1 (3313)
│ │ │ │ -4E2BD Uncompressed Size     0000517A (20858)
│ │ │ │ -4E2C1 Filename Length       0021 (33)
│ │ │ │ -4E2C3 Extra Length          001C (28)
│ │ │ │ -4E2C5 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x4E2C5: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -4E2E6 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -4E2E8   Length              0009 (9)
│ │ │ │ -4E2EA   Flags               03 (3) 'Modification Access'
│ │ │ │ -4E2EB   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4E2EF   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4E2F3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -4E2F5   Length              000B (11)
│ │ │ │ -4E2F7   Version             01 (1)
│ │ │ │ -4E2F8   UID Size            04 (4)
│ │ │ │ -4E2F9   UID                 00000000 (0)
│ │ │ │ -4E2FD   GID Size            04 (4)
│ │ │ │ -4E2FE   GID                 00000000 (0)
│ │ │ │ -4E302 PAYLOAD
│ │ │ │ -
│ │ │ │ -4EFF3 LOCAL HEADER #45      04034B50 (67324752)
│ │ │ │ -4EFF7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -4EFF8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -4EFF9 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -4EFFB Compression Method    0008 (8) 'Deflated'
│ │ │ │ -4EFFD Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -4F001 CRC                   8F01E69C (2399266460)
│ │ │ │ -4F005 Compressed Size       00000468 (1128)
│ │ │ │ -4F009 Uncompressed Size     00000931 (2353)
│ │ │ │ -4F00D Filename Length       001B (27)
│ │ │ │ -4F00F Extra Length          001C (28)
│ │ │ │ -4F011 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x4F011: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -4F02C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -4F02E   Length              0009 (9)
│ │ │ │ -4F030   Flags               03 (3) 'Modification Access'
│ │ │ │ -4F031   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4F035   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4F039 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -4F03B   Length              000B (11)
│ │ │ │ -4F03D   Version             01 (1)
│ │ │ │ -4F03E   UID Size            04 (4)
│ │ │ │ -4F03F   UID                 00000000 (0)
│ │ │ │ -4F043   GID Size            04 (4)
│ │ │ │ -4F044   GID                 00000000 (0)
│ │ │ │ -4F048 PAYLOAD
│ │ │ │ -
│ │ │ │ -4F4B0 LOCAL HEADER #46      04034B50 (67324752)
│ │ │ │ -4F4B4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -4F4B5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -4F4B6 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -4F4B8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -4F4BA Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -4F4BE CRC                   2A5112D6 (709956310)
│ │ │ │ -4F4C2 Compressed Size       000016F1 (5873)
│ │ │ │ -4F4C6 Uncompressed Size     00007A6D (31341)
│ │ │ │ -4F4CA Filename Length       001F (31)
│ │ │ │ -4F4CC Extra Length          001C (28)
│ │ │ │ -4F4CE Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x4F4CE: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -4F4ED Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -4F4EF   Length              0009 (9)
│ │ │ │ -4F4F1   Flags               03 (3) 'Modification Access'
│ │ │ │ -4F4F2   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4F4F6   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -4F4FA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -4F4FC   Length              000B (11)
│ │ │ │ -4F4FE   Version             01 (1)
│ │ │ │ -4F4FF   UID Size            04 (4)
│ │ │ │ -4F500   UID                 00000000 (0)
│ │ │ │ -4F504   GID Size            04 (4)
│ │ │ │ -4F505   GID                 00000000 (0)
│ │ │ │ -4F509 PAYLOAD
│ │ │ │ -
│ │ │ │ -50BFA LOCAL HEADER #47      04034B50 (67324752)
│ │ │ │ -50BFE Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -50BFF Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -50C00 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -50C02 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -50C04 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -50C08 CRC                   1BA8E4E8 (464053480)
│ │ │ │ -50C0C Compressed Size       0000416A (16746)
│ │ │ │ -50C10 Uncompressed Size     0001CF93 (118675)
│ │ │ │ -50C14 Filename Length       0010 (16)
│ │ │ │ -50C16 Extra Length          001C (28)
│ │ │ │ -50C18 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x50C18: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -50C28 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -50C2A   Length              0009 (9)
│ │ │ │ -50C2C   Flags               03 (3) 'Modification Access'
│ │ │ │ -50C2D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -50C31   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -50C35 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -50C37   Length              000B (11)
│ │ │ │ -50C39   Version             01 (1)
│ │ │ │ -50C3A   UID Size            04 (4)
│ │ │ │ -50C3B   UID                 00000000 (0)
│ │ │ │ -50C3F   GID Size            04 (4)
│ │ │ │ -50C40   GID                 00000000 (0)
│ │ │ │ -50C44 PAYLOAD
│ │ │ │ -
│ │ │ │ -54DAE LOCAL HEADER #48      04034B50 (67324752)
│ │ │ │ -54DB2 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -54DB3 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -54DB4 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -54DB6 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -54DB8 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -54DBC CRC                   2020DAF6 (539024118)
│ │ │ │ -54DC0 Compressed Size       00000A94 (2708)
│ │ │ │ -54DC4 Uncompressed Size     00002105 (8453)
│ │ │ │ -54DC8 Filename Length       0014 (20)
│ │ │ │ -54DCA Extra Length          001C (28)
│ │ │ │ -54DCC Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x54DCC: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -54DE0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -54DE2   Length              0009 (9)
│ │ │ │ -54DE4   Flags               03 (3) 'Modification Access'
│ │ │ │ -54DE5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -54DE9   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -54DED Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -54DEF   Length              000B (11)
│ │ │ │ -54DF1   Version             01 (1)
│ │ │ │ -54DF2   UID Size            04 (4)
│ │ │ │ -54DF3   UID                 00000000 (0)
│ │ │ │ -54DF7   GID Size            04 (4)
│ │ │ │ -54DF8   GID                 00000000 (0)
│ │ │ │ -54DFC PAYLOAD
│ │ │ │ -
│ │ │ │ -55890 LOCAL HEADER #49      04034B50 (67324752)
│ │ │ │ -55894 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -55895 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -55896 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -55898 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -5589A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -5589E CRC                   F1FD1FA8 (4059897768)
│ │ │ │ -558A2 Compressed Size       0000AC9D (44189)
│ │ │ │ -558A6 Uncompressed Size     0003E418 (255000)
│ │ │ │ -558AA Filename Length       0017 (23)
│ │ │ │ -558AC Extra Length          001C (28)
│ │ │ │ -558AE Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x558AE: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -558C5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -558C7   Length              0009 (9)
│ │ │ │ -558C9   Flags               03 (3) 'Modification Access'
│ │ │ │ -558CA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -558CE   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -558D2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -558D4   Length              000B (11)
│ │ │ │ -558D6   Version             01 (1)
│ │ │ │ -558D7   UID Size            04 (4)
│ │ │ │ -558D8   UID                 00000000 (0)
│ │ │ │ -558DC   GID Size            04 (4)
│ │ │ │ -558DD   GID                 00000000 (0)
│ │ │ │ -558E1 PAYLOAD
│ │ │ │ -
│ │ │ │ -6057E LOCAL HEADER #50      04034B50 (67324752)
│ │ │ │ -60582 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -60583 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -60584 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -60586 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -60588 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -6058C CRC                   97230023 (2535653411)
│ │ │ │ -60590 Compressed Size       00000401 (1025)
│ │ │ │ -60594 Uncompressed Size     0000093D (2365)
│ │ │ │ -60598 Filename Length       0013 (19)
│ │ │ │ -6059A Extra Length          001C (28)
│ │ │ │ -6059C Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x6059C: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -605AF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -605B1   Length              0009 (9)
│ │ │ │ -605B3   Flags               03 (3) 'Modification Access'
│ │ │ │ -605B4   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -605B8   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -605BC Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -605BE   Length              000B (11)
│ │ │ │ -605C0   Version             01 (1)
│ │ │ │ -605C1   UID Size            04 (4)
│ │ │ │ -605C2   UID                 00000000 (0)
│ │ │ │ -605C6   GID Size            04 (4)
│ │ │ │ -605C7   GID                 00000000 (0)
│ │ │ │ -605CB PAYLOAD
│ │ │ │ -
│ │ │ │ -609CC LOCAL HEADER #51      04034B50 (67324752)
│ │ │ │ -609D0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -609D1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -609D2 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -609D4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -609D6 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -609DA CRC                   15AD4D8E (363679118)
│ │ │ │ -609DE Compressed Size       000014DB (5339)
│ │ │ │ -609E2 Uncompressed Size     0000687B (26747)
│ │ │ │ -609E6 Filename Length       0012 (18)
│ │ │ │ -609E8 Extra Length          001C (28)
│ │ │ │ -609EA Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x609EA: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -609FC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -609FE   Length              0009 (9)
│ │ │ │ -60A00   Flags               03 (3) 'Modification Access'
│ │ │ │ -60A01   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -60A05   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -60A09 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -60A0B   Length              000B (11)
│ │ │ │ -60A0D   Version             01 (1)
│ │ │ │ -60A0E   UID Size            04 (4)
│ │ │ │ -60A0F   UID                 00000000 (0)
│ │ │ │ -60A13   GID Size            04 (4)
│ │ │ │ -60A14   GID                 00000000 (0)
│ │ │ │ -60A18 PAYLOAD
│ │ │ │ -
│ │ │ │ -61EF3 LOCAL HEADER #52      04034B50 (67324752)
│ │ │ │ -61EF7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -61EF8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -61EF9 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -61EFB Compression Method    0008 (8) 'Deflated'
│ │ │ │ -61EFD Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -61F01 CRC                   BDF3884F (3186853967)
│ │ │ │ -61F05 Compressed Size       000011EB (4587)
│ │ │ │ -61F09 Uncompressed Size     000040F5 (16629)
│ │ │ │ -61F0D Filename Length       0012 (18)
│ │ │ │ -61F0F Extra Length          001C (28)
│ │ │ │ -61F11 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x61F11: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -61F23 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -61F25   Length              0009 (9)
│ │ │ │ -61F27   Flags               03 (3) 'Modification Access'
│ │ │ │ -61F28   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -61F2C   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -61F30 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -61F32   Length              000B (11)
│ │ │ │ -61F34   Version             01 (1)
│ │ │ │ -61F35   UID Size            04 (4)
│ │ │ │ -61F36   UID                 00000000 (0)
│ │ │ │ -61F3A   GID Size            04 (4)
│ │ │ │ -61F3B   GID                 00000000 (0)
│ │ │ │ -61F3F PAYLOAD
│ │ │ │ -
│ │ │ │ -6312A LOCAL HEADER #53      04034B50 (67324752)
│ │ │ │ -6312E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -6312F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -63130 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -63132 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -63134 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -63138 CRC                   2C7ABAF2 (746240754)
│ │ │ │ -6313C Compressed Size       000009DA (2522)
│ │ │ │ -63140 Uncompressed Size     00003529 (13609)
│ │ │ │ -63144 Filename Length       0019 (25)
│ │ │ │ -63146 Extra Length          001C (28)
│ │ │ │ -63148 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x63148: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -63161 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -63163   Length              0009 (9)
│ │ │ │ -63165   Flags               03 (3) 'Modification Access'
│ │ │ │ -63166   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6316A   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6316E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -63170   Length              000B (11)
│ │ │ │ -63172   Version             01 (1)
│ │ │ │ -63173   UID Size            04 (4)
│ │ │ │ -63174   UID                 00000000 (0)
│ │ │ │ -63178   GID Size            04 (4)
│ │ │ │ -63179   GID                 00000000 (0)
│ │ │ │ -6317D PAYLOAD
│ │ │ │ -
│ │ │ │ -63B57 LOCAL HEADER #54      04034B50 (67324752)
│ │ │ │ -63B5B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -63B5C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -63B5D General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -63B5F Compression Method    0008 (8) 'Deflated'
│ │ │ │ -63B61 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -63B65 CRC                   D69E8D28 (3600715048)
│ │ │ │ -63B69 Compressed Size       000018B1 (6321)
│ │ │ │ -63B6D Uncompressed Size     0000A605 (42501)
│ │ │ │ -63B71 Filename Length       0019 (25)
│ │ │ │ -63B73 Extra Length          001C (28)
│ │ │ │ -63B75 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x63B75: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -63B8E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -63B90   Length              0009 (9)
│ │ │ │ -63B92   Flags               03 (3) 'Modification Access'
│ │ │ │ -63B93   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -63B97   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -63B9B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -63B9D   Length              000B (11)
│ │ │ │ -63B9F   Version             01 (1)
│ │ │ │ -63BA0   UID Size            04 (4)
│ │ │ │ -63BA1   UID                 00000000 (0)
│ │ │ │ -63BA5   GID Size            04 (4)
│ │ │ │ -63BA6   GID                 00000000 (0)
│ │ │ │ -63BAA PAYLOAD
│ │ │ │ -
│ │ │ │ -6545B LOCAL HEADER #55      04034B50 (67324752)
│ │ │ │ -6545F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -65460 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -65461 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -65463 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -65465 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -65469 CRC                   47E0D6DC (1205917404)
│ │ │ │ -6546D Compressed Size       0000177E (6014)
│ │ │ │ -65471 Uncompressed Size     0000472C (18220)
│ │ │ │ -65475 Filename Length       0014 (20)
│ │ │ │ -65477 Extra Length          001C (28)
│ │ │ │ -65479 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x65479: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -6548D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -6548F   Length              0009 (9)
│ │ │ │ -65491   Flags               03 (3) 'Modification Access'
│ │ │ │ -65492   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -65496   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6549A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -6549C   Length              000B (11)
│ │ │ │ -6549E   Version             01 (1)
│ │ │ │ -6549F   UID Size            04 (4)
│ │ │ │ -654A0   UID                 00000000 (0)
│ │ │ │ -654A4   GID Size            04 (4)
│ │ │ │ -654A5   GID                 00000000 (0)
│ │ │ │ -654A9 PAYLOAD
│ │ │ │ -
│ │ │ │ -66C27 LOCAL HEADER #56      04034B50 (67324752)
│ │ │ │ -66C2B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -66C2C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -66C2D General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -66C2F Compression Method    0008 (8) 'Deflated'
│ │ │ │ -66C31 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -66C35 CRC                   EDF51269 (3992261225)
│ │ │ │ -66C39 Compressed Size       0000040B (1035)
│ │ │ │ -66C3D Uncompressed Size     00000825 (2085)
│ │ │ │ -66C41 Filename Length       001C (28)
│ │ │ │ -66C43 Extra Length          001C (28)
│ │ │ │ -66C45 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x66C45: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -66C61 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -66C63   Length              0009 (9)
│ │ │ │ -66C65   Flags               03 (3) 'Modification Access'
│ │ │ │ -66C66   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -66C6A   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -66C6E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -66C70   Length              000B (11)
│ │ │ │ -66C72   Version             01 (1)
│ │ │ │ -66C73   UID Size            04 (4)
│ │ │ │ -66C74   UID                 00000000 (0)
│ │ │ │ -66C78   GID Size            04 (4)
│ │ │ │ -66C79   GID                 00000000 (0)
│ │ │ │ -66C7D PAYLOAD
│ │ │ │ -
│ │ │ │ -67088 LOCAL HEADER #57      04034B50 (67324752)
│ │ │ │ -6708C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -6708D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -6708E General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -67090 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -67092 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -67096 CRC                   AC935B99 (2895338393)
│ │ │ │ -6709A Compressed Size       00002483 (9347)
│ │ │ │ -6709E Uncompressed Size     0000B56F (46447)
│ │ │ │ -670A2 Filename Length       001F (31)
│ │ │ │ -670A4 Extra Length          001C (28)
│ │ │ │ -670A6 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x670A6: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -670C5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -670C7   Length              0009 (9)
│ │ │ │ -670C9   Flags               03 (3) 'Modification Access'
│ │ │ │ -670CA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -670CE   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -670D2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -670D4   Length              000B (11)
│ │ │ │ -670D6   Version             01 (1)
│ │ │ │ -670D7   UID Size            04 (4)
│ │ │ │ -670D8   UID                 00000000 (0)
│ │ │ │ -670DC   GID Size            04 (4)
│ │ │ │ -670DD   GID                 00000000 (0)
│ │ │ │ -670E1 PAYLOAD
│ │ │ │ -
│ │ │ │ -69564 LOCAL HEADER #58      04034B50 (67324752)
│ │ │ │ -69568 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -69569 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -6956A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -6956C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -6956E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -69572 CRC                   EE677FF5 (3999760373)
│ │ │ │ -69576 Compressed Size       00000E81 (3713)
│ │ │ │ -6957A Uncompressed Size     000052D9 (21209)
│ │ │ │ -6957E Filename Length       001F (31)
│ │ │ │ -69580 Extra Length          001C (28)
│ │ │ │ -69582 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x69582: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -695A1 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -695A3   Length              0009 (9)
│ │ │ │ -695A5   Flags               03 (3) 'Modification Access'
│ │ │ │ -695A6   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -695AA   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -695AE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -695B0   Length              000B (11)
│ │ │ │ -695B2   Version             01 (1)
│ │ │ │ -695B3   UID Size            04 (4)
│ │ │ │ -695B4   UID                 00000000 (0)
│ │ │ │ -695B8   GID Size            04 (4)
│ │ │ │ -695B9   GID                 00000000 (0)
│ │ │ │ -695BD PAYLOAD
│ │ │ │ -
│ │ │ │ -6A43E LOCAL HEADER #59      04034B50 (67324752)
│ │ │ │ -6A442 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -6A443 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -6A444 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -6A446 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -6A448 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -6A44C CRC                   651C981F (1696372767)
│ │ │ │ -6A450 Compressed Size       00000A43 (2627)
│ │ │ │ -6A454 Uncompressed Size     0000247A (9338)
│ │ │ │ -6A458 Filename Length       0013 (19)
│ │ │ │ -6A45A Extra Length          001C (28)
│ │ │ │ -6A45C Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x6A45C: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -6A46F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -6A471   Length              0009 (9)
│ │ │ │ -6A473   Flags               03 (3) 'Modification Access'
│ │ │ │ -6A474   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6A478   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6A47C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -6A47E   Length              000B (11)
│ │ │ │ -6A480   Version             01 (1)
│ │ │ │ -6A481   UID Size            04 (4)
│ │ │ │ -6A482   UID                 00000000 (0)
│ │ │ │ -6A486   GID Size            04 (4)
│ │ │ │ -6A487   GID                 00000000 (0)
│ │ │ │ -6A48B PAYLOAD
│ │ │ │ -
│ │ │ │ -6AECE LOCAL HEADER #60      04034B50 (67324752)
│ │ │ │ -6AED2 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -6AED3 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -6AED4 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -6AED6 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -6AED8 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -6AEDC CRC                   6A1CF0DA (1780281562)
│ │ │ │ -6AEE0 Compressed Size       00002486 (9350)
│ │ │ │ -6AEE4 Uncompressed Size     0000B84C (47180)
│ │ │ │ -6AEE8 Filename Length       0019 (25)
│ │ │ │ -6AEEA Extra Length          001C (28)
│ │ │ │ -6AEEC Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x6AEEC: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -6AF05 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -6AF07   Length              0009 (9)
│ │ │ │ -6AF09   Flags               03 (3) 'Modification Access'
│ │ │ │ -6AF0A   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6AF0E   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6AF12 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -6AF14   Length              000B (11)
│ │ │ │ -6AF16   Version             01 (1)
│ │ │ │ -6AF17   UID Size            04 (4)
│ │ │ │ -6AF18   UID                 00000000 (0)
│ │ │ │ -6AF1C   GID Size            04 (4)
│ │ │ │ -6AF1D   GID                 00000000 (0)
│ │ │ │ -6AF21 PAYLOAD
│ │ │ │ -
│ │ │ │ -6D3A7 LOCAL HEADER #61      04034B50 (67324752)
│ │ │ │ -6D3AB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -6D3AC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -6D3AD General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -6D3AF Compression Method    0008 (8) 'Deflated'
│ │ │ │ -6D3B1 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -6D3B5 CRC                   E9583C9A (3914874010)
│ │ │ │ -6D3B9 Compressed Size       00000EF9 (3833)
│ │ │ │ -6D3BD Uncompressed Size     00003A2C (14892)
│ │ │ │ -6D3C1 Filename Length       0024 (36)
│ │ │ │ -6D3C3 Extra Length          001C (28)
│ │ │ │ -6D3C5 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x6D3C5: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -6D3E9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -6D3EB   Length              0009 (9)
│ │ │ │ -6D3ED   Flags               03 (3) 'Modification Access'
│ │ │ │ -6D3EE   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6D3F2   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6D3F6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -6D3F8   Length              000B (11)
│ │ │ │ -6D3FA   Version             01 (1)
│ │ │ │ -6D3FB   UID Size            04 (4)
│ │ │ │ -6D3FC   UID                 00000000 (0)
│ │ │ │ -6D400   GID Size            04 (4)
│ │ │ │ -6D401   GID                 00000000 (0)
│ │ │ │ -6D405 PAYLOAD
│ │ │ │ -
│ │ │ │ -6E2FE LOCAL HEADER #62      04034B50 (67324752)
│ │ │ │ -6E302 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -6E303 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -6E304 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -6E306 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -6E308 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -6E30C CRC                   0D165AC6 (219568838)
│ │ │ │ -6E310 Compressed Size       00001AC1 (6849)
│ │ │ │ -6E314 Uncompressed Size     00005EDC (24284)
│ │ │ │ -6E318 Filename Length       0017 (23)
│ │ │ │ -6E31A Extra Length          001C (28)
│ │ │ │ -6E31C Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x6E31C: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -6E333 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -6E335   Length              0009 (9)
│ │ │ │ -6E337   Flags               03 (3) 'Modification Access'
│ │ │ │ -6E338   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6E33C   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6E340 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -6E342   Length              000B (11)
│ │ │ │ -6E344   Version             01 (1)
│ │ │ │ -6E345   UID Size            04 (4)
│ │ │ │ -6E346   UID                 00000000 (0)
│ │ │ │ -6E34A   GID Size            04 (4)
│ │ │ │ -6E34B   GID                 00000000 (0)
│ │ │ │ -6E34F PAYLOAD
│ │ │ │ -
│ │ │ │ -6FE10 LOCAL HEADER #63      04034B50 (67324752)
│ │ │ │ -6FE14 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -6FE15 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -6FE16 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -6FE18 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -6FE1A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -6FE1E CRC                   11E32AF1 (300100337)
│ │ │ │ -6FE22 Compressed Size       00000ED3 (3795)
│ │ │ │ -6FE26 Uncompressed Size     000038E2 (14562)
│ │ │ │ -6FE2A Filename Length       0023 (35)
│ │ │ │ -6FE2C Extra Length          001C (28)
│ │ │ │ -6FE2E Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x6FE2E: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -6FE51 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -6FE53   Length              0009 (9)
│ │ │ │ -6FE55   Flags               03 (3) 'Modification Access'
│ │ │ │ -6FE56   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6FE5A   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -6FE5E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -6FE60   Length              000B (11)
│ │ │ │ -6FE62   Version             01 (1)
│ │ │ │ -6FE63   UID Size            04 (4)
│ │ │ │ -6FE64   UID                 00000000 (0)
│ │ │ │ -6FE68   GID Size            04 (4)
│ │ │ │ -6FE69   GID                 00000000 (0)
│ │ │ │ -6FE6D PAYLOAD
│ │ │ │ -
│ │ │ │ -70D40 LOCAL HEADER #64      04034B50 (67324752)
│ │ │ │ -70D44 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -70D45 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -70D46 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -70D48 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -70D4A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -70D4E CRC                   2DB7929F (767005343)
│ │ │ │ -70D52 Compressed Size       00000113 (275)
│ │ │ │ -70D56 Uncompressed Size     000001F3 (499)
│ │ │ │ -70D5A Filename Length       001B (27)
│ │ │ │ -70D5C Extra Length          001C (28)
│ │ │ │ -70D5E Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x70D5E: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -70D79 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -70D7B   Length              0009 (9)
│ │ │ │ -70D7D   Flags               03 (3) 'Modification Access'
│ │ │ │ -70D7E   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -70D82   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -70D86 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -70D88   Length              000B (11)
│ │ │ │ -70D8A   Version             01 (1)
│ │ │ │ -70D8B   UID Size            04 (4)
│ │ │ │ -70D8C   UID                 00000000 (0)
│ │ │ │ -70D90   GID Size            04 (4)
│ │ │ │ -70D91   GID                 00000000 (0)
│ │ │ │ -70D95 PAYLOAD
│ │ │ │ -
│ │ │ │ -70EA8 LOCAL HEADER #65      04034B50 (67324752)
│ │ │ │ -70EAC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -70EAD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -70EAE General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -70EB0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -70EB2 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -70EB6 CRC                   BC4620C3 (3158712515)
│ │ │ │ -70EBA Compressed Size       00001892 (6290)
│ │ │ │ -70EBE Uncompressed Size     00008FAC (36780)
│ │ │ │ -70EC2 Filename Length       001D (29)
│ │ │ │ -70EC4 Extra Length          001C (28)
│ │ │ │ -70EC6 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x70EC6: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -70EE3 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -70EE5   Length              0009 (9)
│ │ │ │ -70EE7   Flags               03 (3) 'Modification Access'
│ │ │ │ -70EE8   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -70EEC   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -70EF0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -70EF2   Length              000B (11)
│ │ │ │ -70EF4   Version             01 (1)
│ │ │ │ -70EF5   UID Size            04 (4)
│ │ │ │ -70EF6   UID                 00000000 (0)
│ │ │ │ -70EFA   GID Size            04 (4)
│ │ │ │ -70EFB   GID                 00000000 (0)
│ │ │ │ -70EFF PAYLOAD
│ │ │ │ -
│ │ │ │ -72791 LOCAL HEADER #66      04034B50 (67324752)
│ │ │ │ -72795 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -72796 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -72797 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -72799 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -7279B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -7279F CRC                   63FED801 (1677645825)
│ │ │ │ -727A3 Compressed Size       0000164D (5709)
│ │ │ │ -727A7 Uncompressed Size     00003A9B (15003)
│ │ │ │ -727AB Filename Length       0015 (21)
│ │ │ │ -727AD Extra Length          001C (28)
│ │ │ │ -727AF Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x727AF: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -727C4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -727C6   Length              0009 (9)
│ │ │ │ -727C8   Flags               03 (3) 'Modification Access'
│ │ │ │ -727C9   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -727CD   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -727D1 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -727D3   Length              000B (11)
│ │ │ │ -727D5   Version             01 (1)
│ │ │ │ -727D6   UID Size            04 (4)
│ │ │ │ -727D7   UID                 00000000 (0)
│ │ │ │ -727DB   GID Size            04 (4)
│ │ │ │ -727DC   GID                 00000000 (0)
│ │ │ │ -727E0 PAYLOAD
│ │ │ │ -
│ │ │ │ -73E2D LOCAL HEADER #67      04034B50 (67324752)
│ │ │ │ -73E31 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -73E32 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -73E33 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -73E35 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -73E37 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -73E3B CRC                   ADE907F6 (2917730294)
│ │ │ │ -73E3F Compressed Size       00003B50 (15184)
│ │ │ │ -73E43 Uncompressed Size     0001185B (71771)
│ │ │ │ -73E47 Filename Length       0016 (22)
│ │ │ │ -73E49 Extra Length          001C (28)
│ │ │ │ -73E4B Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x73E4B: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -73E61 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -73E63   Length              0009 (9)
│ │ │ │ -73E65   Flags               03 (3) 'Modification Access'
│ │ │ │ -73E66   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -73E6A   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -73E6E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -73E70   Length              000B (11)
│ │ │ │ -73E72   Version             01 (1)
│ │ │ │ -73E73   UID Size            04 (4)
│ │ │ │ -73E74   UID                 00000000 (0)
│ │ │ │ -73E78   GID Size            04 (4)
│ │ │ │ -73E79   GID                 00000000 (0)
│ │ │ │ -73E7D PAYLOAD
│ │ │ │ -
│ │ │ │ -779CD LOCAL HEADER #68      04034B50 (67324752)
│ │ │ │ -779D1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -779D2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -779D3 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -779D5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -779D7 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -779DB CRC                   7DF00FFC (2112884732)
│ │ │ │ -779DF Compressed Size       00003E85 (16005)
│ │ │ │ -779E3 Uncompressed Size     0001C17B (115067)
│ │ │ │ -779E7 Filename Length       0019 (25)
│ │ │ │ -779E9 Extra Length          001C (28)
│ │ │ │ -779EB Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x779EB: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -77A04 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -77A06   Length              0009 (9)
│ │ │ │ -77A08   Flags               03 (3) 'Modification Access'
│ │ │ │ -77A09   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -77A0D   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -77A11 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -77A13   Length              000B (11)
│ │ │ │ -77A15   Version             01 (1)
│ │ │ │ -77A16   UID Size            04 (4)
│ │ │ │ -77A17   UID                 00000000 (0)
│ │ │ │ -77A1B   GID Size            04 (4)
│ │ │ │ -77A1C   GID                 00000000 (0)
│ │ │ │ -77A20 PAYLOAD
│ │ │ │ -
│ │ │ │ -7B8A5 LOCAL HEADER #69      04034B50 (67324752)
│ │ │ │ -7B8A9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -7B8AA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -7B8AB General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -7B8AD Compression Method    0008 (8) 'Deflated'
│ │ │ │ -7B8AF Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -7B8B3 CRC                   08716215 (141648405)
│ │ │ │ -7B8B7 Compressed Size       00000833 (2099)
│ │ │ │ -7B8BB Uncompressed Size     00003383 (13187)
│ │ │ │ -7B8BF Filename Length       0011 (17)
│ │ │ │ -7B8C1 Extra Length          001C (28)
│ │ │ │ -7B8C3 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x7B8C3: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -7B8D4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -7B8D6   Length              0009 (9)
│ │ │ │ -7B8D8   Flags               03 (3) 'Modification Access'
│ │ │ │ -7B8D9   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -7B8DD   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -7B8E1 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -7B8E3   Length              000B (11)
│ │ │ │ -7B8E5   Version             01 (1)
│ │ │ │ -7B8E6   UID Size            04 (4)
│ │ │ │ -7B8E7   UID                 00000000 (0)
│ │ │ │ -7B8EB   GID Size            04 (4)
│ │ │ │ -7B8EC   GID                 00000000 (0)
│ │ │ │ -7B8F0 PAYLOAD
│ │ │ │ -
│ │ │ │ -7C123 LOCAL HEADER #70      04034B50 (67324752)
│ │ │ │ -7C127 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -7C128 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -7C129 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -7C12B Compression Method    0008 (8) 'Deflated'
│ │ │ │ -7C12D Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -7C131 CRC                   9B8ACD82 (2609565058)
│ │ │ │ -7C135 Compressed Size       00005188 (20872)
│ │ │ │ -7C139 Uncompressed Size     0001FB6C (129900)
│ │ │ │ -7C13D Filename Length       0015 (21)
│ │ │ │ -7C13F Extra Length          001C (28)
│ │ │ │ -7C141 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x7C141: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -7C156 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -7C158   Length              0009 (9)
│ │ │ │ -7C15A   Flags               03 (3) 'Modification Access'
│ │ │ │ -7C15B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -7C15F   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -7C163 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -7C165   Length              000B (11)
│ │ │ │ -7C167   Version             01 (1)
│ │ │ │ -7C168   UID Size            04 (4)
│ │ │ │ -7C169   UID                 00000000 (0)
│ │ │ │ -7C16D   GID Size            04 (4)
│ │ │ │ -7C16E   GID                 00000000 (0)
│ │ │ │ -7C172 PAYLOAD
│ │ │ │ -
│ │ │ │ -812FA LOCAL HEADER #71      04034B50 (67324752)
│ │ │ │ -812FE Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -812FF Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -81300 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -81302 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -81304 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -81308 CRC                   535E57D6 (1398691798)
│ │ │ │ -8130C Compressed Size       00001B05 (6917)
│ │ │ │ -81310 Uncompressed Size     000081CF (33231)
│ │ │ │ -81314 Filename Length       0019 (25)
│ │ │ │ -81316 Extra Length          001C (28)
│ │ │ │ -81318 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x81318: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -81331 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -81333   Length              0009 (9)
│ │ │ │ -81335   Flags               03 (3) 'Modification Access'
│ │ │ │ -81336   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8133A   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8133E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -81340   Length              000B (11)
│ │ │ │ -81342   Version             01 (1)
│ │ │ │ -81343   UID Size            04 (4)
│ │ │ │ -81344   UID                 00000000 (0)
│ │ │ │ -81348   GID Size            04 (4)
│ │ │ │ -81349   GID                 00000000 (0)
│ │ │ │ -8134D PAYLOAD
│ │ │ │ -
│ │ │ │ -82E52 LOCAL HEADER #72      04034B50 (67324752)
│ │ │ │ -82E56 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -82E57 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -82E58 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -82E5A Compression Method    0008 (8) 'Deflated'
│ │ │ │ -82E5C Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -82E60 CRC                   02D5C73B (47564603)
│ │ │ │ -82E64 Compressed Size       00000D96 (3478)
│ │ │ │ -82E68 Uncompressed Size     00002E9F (11935)
│ │ │ │ -82E6C Filename Length       0018 (24)
│ │ │ │ -82E6E Extra Length          001C (28)
│ │ │ │ -82E70 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x82E70: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -82E88 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -82E8A   Length              0009 (9)
│ │ │ │ -82E8C   Flags               03 (3) 'Modification Access'
│ │ │ │ -82E8D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -82E91   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -82E95 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -82E97   Length              000B (11)
│ │ │ │ -82E99   Version             01 (1)
│ │ │ │ -82E9A   UID Size            04 (4)
│ │ │ │ -82E9B   UID                 00000000 (0)
│ │ │ │ -82E9F   GID Size            04 (4)
│ │ │ │ -82EA0   GID                 00000000 (0)
│ │ │ │ -82EA4 PAYLOAD
│ │ │ │ -
│ │ │ │ -83C3A LOCAL HEADER #73      04034B50 (67324752)
│ │ │ │ -83C3E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -83C3F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -83C40 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -83C42 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -83C44 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -83C48 CRC                   B429472D (3022604077)
│ │ │ │ -83C4C Compressed Size       000001E1 (481)
│ │ │ │ -83C50 Uncompressed Size     00000323 (803)
│ │ │ │ -83C54 Filename Length       0011 (17)
│ │ │ │ -83C56 Extra Length          001C (28)
│ │ │ │ -83C58 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x83C58: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -83C69 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -83C6B   Length              0009 (9)
│ │ │ │ -83C6D   Flags               03 (3) 'Modification Access'
│ │ │ │ -83C6E   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -83C72   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -83C76 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -83C78   Length              000B (11)
│ │ │ │ -83C7A   Version             01 (1)
│ │ │ │ -83C7B   UID Size            04 (4)
│ │ │ │ -83C7C   UID                 00000000 (0)
│ │ │ │ -83C80   GID Size            04 (4)
│ │ │ │ -83C81   GID                 00000000 (0)
│ │ │ │ -83C85 PAYLOAD
│ │ │ │ -
│ │ │ │ -83E66 LOCAL HEADER #74      04034B50 (67324752)
│ │ │ │ -83E6A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -83E6B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -83E6C General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -83E6E Compression Method    0008 (8) 'Deflated'
│ │ │ │ -83E70 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -83E74 CRC                   1E45F0E3 (507900131)
│ │ │ │ -83E78 Compressed Size       000006C1 (1729)
│ │ │ │ -83E7C Uncompressed Size     00001439 (5177)
│ │ │ │ -83E80 Filename Length       0019 (25)
│ │ │ │ -83E82 Extra Length          001C (28)
│ │ │ │ -83E84 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x83E84: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -83E9D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -83E9F   Length              0009 (9)
│ │ │ │ -83EA1   Flags               03 (3) 'Modification Access'
│ │ │ │ -83EA2   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -83EA6   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -83EAA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -83EAC   Length              000B (11)
│ │ │ │ -83EAE   Version             01 (1)
│ │ │ │ -83EAF   UID Size            04 (4)
│ │ │ │ -83EB0   UID                 00000000 (0)
│ │ │ │ -83EB4   GID Size            04 (4)
│ │ │ │ -83EB5   GID                 00000000 (0)
│ │ │ │ -83EB9 PAYLOAD
│ │ │ │ -
│ │ │ │ -8457A LOCAL HEADER #75      04034B50 (67324752)
│ │ │ │ -8457E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -8457F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -84580 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -84582 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -84584 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -84588 CRC                   31106466 (823157862)
│ │ │ │ -8458C Compressed Size       00001B86 (7046)
│ │ │ │ -84590 Uncompressed Size     00009F03 (40707)
│ │ │ │ -84594 Filename Length       0018 (24)
│ │ │ │ -84596 Extra Length          001C (28)
│ │ │ │ -84598 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x84598: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -845B0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -845B2   Length              0009 (9)
│ │ │ │ -845B4   Flags               03 (3) 'Modification Access'
│ │ │ │ -845B5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -845B9   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -845BD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -845BF   Length              000B (11)
│ │ │ │ -845C1   Version             01 (1)
│ │ │ │ -845C2   UID Size            04 (4)
│ │ │ │ -845C3   UID                 00000000 (0)
│ │ │ │ -845C7   GID Size            04 (4)
│ │ │ │ -845C8   GID                 00000000 (0)
│ │ │ │ -845CC PAYLOAD
│ │ │ │ -
│ │ │ │ -86152 LOCAL HEADER #76      04034B50 (67324752)
│ │ │ │ -86156 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -86157 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -86158 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -8615A Compression Method    0008 (8) 'Deflated'
│ │ │ │ -8615C Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -86160 CRC                   EAA681B2 (3936780722)
│ │ │ │ -86164 Compressed Size       000016FB (5883)
│ │ │ │ -86168 Uncompressed Size     00008AB6 (35510)
│ │ │ │ -8616C Filename Length       0012 (18)
│ │ │ │ -8616E Extra Length          001C (28)
│ │ │ │ -86170 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x86170: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -86182 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -86184   Length              0009 (9)
│ │ │ │ -86186   Flags               03 (3) 'Modification Access'
│ │ │ │ -86187   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8618B   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8618F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -86191   Length              000B (11)
│ │ │ │ -86193   Version             01 (1)
│ │ │ │ -86194   UID Size            04 (4)
│ │ │ │ -86195   UID                 00000000 (0)
│ │ │ │ -86199   GID Size            04 (4)
│ │ │ │ -8619A   GID                 00000000 (0)
│ │ │ │ -8619E PAYLOAD
│ │ │ │ -
│ │ │ │ -87899 LOCAL HEADER #77      04034B50 (67324752)
│ │ │ │ -8789D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -8789E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -8789F General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -878A1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -878A3 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -878A7 CRC                   2B5B6715 (727410453)
│ │ │ │ -878AB Compressed Size       00001E12 (7698)
│ │ │ │ -878AF Uncompressed Size     00008803 (34819)
│ │ │ │ -878B3 Filename Length       0016 (22)
│ │ │ │ -878B5 Extra Length          001C (28)
│ │ │ │ -878B7 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x878B7: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -878CD Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -878CF   Length              0009 (9)
│ │ │ │ -878D1   Flags               03 (3) 'Modification Access'
│ │ │ │ -878D2   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -878D6   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -878DA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -878DC   Length              000B (11)
│ │ │ │ -878DE   Version             01 (1)
│ │ │ │ -878DF   UID Size            04 (4)
│ │ │ │ -878E0   UID                 00000000 (0)
│ │ │ │ -878E4   GID Size            04 (4)
│ │ │ │ -878E5   GID                 00000000 (0)
│ │ │ │ -878E9 PAYLOAD
│ │ │ │ -
│ │ │ │ -896FB LOCAL HEADER #78      04034B50 (67324752)
│ │ │ │ -896FF Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -89700 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -89701 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -89703 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -89705 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -89709 CRC                   F1BBDD3F (4055620927)
│ │ │ │ -8970D Compressed Size       000029A9 (10665)
│ │ │ │ -89711 Uncompressed Size     0000D04F (53327)
│ │ │ │ -89715 Filename Length       001A (26)
│ │ │ │ -89717 Extra Length          001C (28)
│ │ │ │ -89719 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x89719: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -89733 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -89735   Length              0009 (9)
│ │ │ │ -89737   Flags               03 (3) 'Modification Access'
│ │ │ │ -89738   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8973C   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -89740 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -89742   Length              000B (11)
│ │ │ │ -89744   Version             01 (1)
│ │ │ │ -89745   UID Size            04 (4)
│ │ │ │ -89746   UID                 00000000 (0)
│ │ │ │ -8974A   GID Size            04 (4)
│ │ │ │ -8974B   GID                 00000000 (0)
│ │ │ │ -8974F PAYLOAD
│ │ │ │ -
│ │ │ │ -8C0F8 LOCAL HEADER #79      04034B50 (67324752)
│ │ │ │ -8C0FC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -8C0FD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -8C0FE General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -8C100 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -8C102 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -8C106 CRC                   DC838374 (3699606388)
│ │ │ │ -8C10A Compressed Size       000009AB (2475)
│ │ │ │ -8C10E Uncompressed Size     00001DB6 (7606)
│ │ │ │ -8C112 Filename Length       0018 (24)
│ │ │ │ -8C114 Extra Length          001C (28)
│ │ │ │ -8C116 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x8C116: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -8C12E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -8C130   Length              0009 (9)
│ │ │ │ -8C132   Flags               03 (3) 'Modification Access'
│ │ │ │ -8C133   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8C137   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8C13B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -8C13D   Length              000B (11)
│ │ │ │ -8C13F   Version             01 (1)
│ │ │ │ -8C140   UID Size            04 (4)
│ │ │ │ -8C141   UID                 00000000 (0)
│ │ │ │ -8C145   GID Size            04 (4)
│ │ │ │ -8C146   GID                 00000000 (0)
│ │ │ │ -8C14A PAYLOAD
│ │ │ │ -
│ │ │ │ -8CAF5 LOCAL HEADER #80      04034B50 (67324752)
│ │ │ │ -8CAF9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -8CAFA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -8CAFB General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -8CAFD Compression Method    0008 (8) 'Deflated'
│ │ │ │ -8CAFF Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -8CB03 CRC                   F5E2129F (4125233823)
│ │ │ │ -8CB07 Compressed Size       000016BC (5820)
│ │ │ │ -8CB0B Uncompressed Size     000016CD (5837)
│ │ │ │ -8CB0F Filename Length       0015 (21)
│ │ │ │ -8CB11 Extra Length          001C (28)
│ │ │ │ -8CB13 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x8CB13: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -8CB28 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -8CB2A   Length              0009 (9)
│ │ │ │ -8CB2C   Flags               03 (3) 'Modification Access'
│ │ │ │ -8CB2D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8CB31   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8CB35 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -8CB37   Length              000B (11)
│ │ │ │ -8CB39   Version             01 (1)
│ │ │ │ -8CB3A   UID Size            04 (4)
│ │ │ │ -8CB3B   UID                 00000000 (0)
│ │ │ │ -8CB3F   GID Size            04 (4)
│ │ │ │ -8CB40   GID                 00000000 (0)
│ │ │ │ -8CB44 PAYLOAD
│ │ │ │ -
│ │ │ │ -8E200 LOCAL HEADER #81      04034B50 (67324752)
│ │ │ │ -8E204 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -8E205 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -8E206 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -8E208 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -8E20A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -8E20E CRC                   F5E2129F (4125233823)
│ │ │ │ -8E212 Compressed Size       000016BC (5820)
│ │ │ │ -8E216 Uncompressed Size     000016CD (5837)
│ │ │ │ -8E21A Filename Length       001C (28)
│ │ │ │ -8E21C Extra Length          001C (28)
│ │ │ │ -8E21E Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x8E21E: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -8E23A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -8E23C   Length              0009 (9)
│ │ │ │ -8E23E   Flags               03 (3) 'Modification Access'
│ │ │ │ -8E23F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8E243   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8E247 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -8E249   Length              000B (11)
│ │ │ │ -8E24B   Version             01 (1)
│ │ │ │ -8E24C   UID Size            04 (4)
│ │ │ │ -8E24D   UID                 00000000 (0)
│ │ │ │ -8E251   GID Size            04 (4)
│ │ │ │ -8E252   GID                 00000000 (0)
│ │ │ │ -8E256 PAYLOAD
│ │ │ │ -
│ │ │ │ -8F912 LOCAL HEADER #82      04034B50 (67324752)
│ │ │ │ -8F916 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -8F917 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -8F918 General Purpose Flag  0000 (0)
│ │ │ │ -8F91A Compression Method    0000 (0) 'Stored'
│ │ │ │ -8F91C Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -8F920 CRC                   FC95F24B (4237685323)
│ │ │ │ -8F924 Compressed Size       00001B84 (7044)
│ │ │ │ -8F928 Uncompressed Size     00001B84 (7044)
│ │ │ │ -8F92C Filename Length       0016 (22)
│ │ │ │ -8F92E Extra Length          001C (28)
│ │ │ │ -8F930 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x8F930: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -8F946 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -8F948   Length              0009 (9)
│ │ │ │ -8F94A   Flags               03 (3) 'Modification Access'
│ │ │ │ -8F94B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8F94F   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -8F953 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -8F955   Length              000B (11)
│ │ │ │ -8F957   Version             01 (1)
│ │ │ │ -8F958   UID Size            04 (4)
│ │ │ │ -8F959   UID                 00000000 (0)
│ │ │ │ -8F95D   GID Size            04 (4)
│ │ │ │ -8F95E   GID                 00000000 (0)
│ │ │ │ -8F962 PAYLOAD
│ │ │ │ -
│ │ │ │ -914E6 LOCAL HEADER #83      04034B50 (67324752)
│ │ │ │ -914EA Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -914EB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -914EC General Purpose Flag  0000 (0)
│ │ │ │ -914EE Compression Method    0000 (0) 'Stored'
│ │ │ │ -914F0 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -914F4 CRC                   D0D71F86 (3503759238)
│ │ │ │ -914F8 Compressed Size       00000B7B (2939)
│ │ │ │ -914FC Uncompressed Size     00000B7B (2939)
│ │ │ │ -91500 Filename Length       0016 (22)
│ │ │ │ -91502 Extra Length          001C (28)
│ │ │ │ -91504 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x91504: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9151A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9151C   Length              0009 (9)
│ │ │ │ -9151E   Flags               03 (3) 'Modification Access'
│ │ │ │ -9151F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -91523   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -91527 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -91529   Length              000B (11)
│ │ │ │ -9152B   Version             01 (1)
│ │ │ │ -9152C   UID Size            04 (4)
│ │ │ │ -9152D   UID                 00000000 (0)
│ │ │ │ -91531   GID Size            04 (4)
│ │ │ │ -91532   GID                 00000000 (0)
│ │ │ │ -91536 PAYLOAD
│ │ │ │ -
│ │ │ │ -920B1 LOCAL HEADER #84      04034B50 (67324752)
│ │ │ │ -920B5 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -920B6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -920B7 General Purpose Flag  0000 (0)
│ │ │ │ -920B9 Compression Method    0000 (0) 'Stored'
│ │ │ │ -920BB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -920BF CRC                   FFF9C4D2 (4294558930)
│ │ │ │ -920C3 Compressed Size       0000138F (5007)
│ │ │ │ -920C7 Uncompressed Size     0000138F (5007)
│ │ │ │ -920CB Filename Length       0016 (22)
│ │ │ │ -920CD Extra Length          001C (28)
│ │ │ │ -920CF Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x920CF: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -920E5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -920E7   Length              0009 (9)
│ │ │ │ -920E9   Flags               03 (3) 'Modification Access'
│ │ │ │ -920EA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -920EE   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -920F2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -920F4   Length              000B (11)
│ │ │ │ -920F6   Version             01 (1)
│ │ │ │ -920F7   UID Size            04 (4)
│ │ │ │ -920F8   UID                 00000000 (0)
│ │ │ │ -920FC   GID Size            04 (4)
│ │ │ │ -920FD   GID                 00000000 (0)
│ │ │ │ -92101 PAYLOAD
│ │ │ │ -
│ │ │ │ -93490 LOCAL HEADER #85      04034B50 (67324752)
│ │ │ │ -93494 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -93495 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -93496 General Purpose Flag  0000 (0)
│ │ │ │ -93498 Compression Method    0000 (0) 'Stored'
│ │ │ │ -9349A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9349E CRC                   A1037E8E (2701360782)
│ │ │ │ -934A2 Compressed Size       0000145E (5214)
│ │ │ │ -934A6 Uncompressed Size     0000145E (5214)
│ │ │ │ -934AA Filename Length       0016 (22)
│ │ │ │ -934AC Extra Length          001C (28)
│ │ │ │ -934AE Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x934AE: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -934C4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -934C6   Length              0009 (9)
│ │ │ │ -934C8   Flags               03 (3) 'Modification Access'
│ │ │ │ -934C9   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -934CD   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -934D1 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -934D3   Length              000B (11)
│ │ │ │ -934D5   Version             01 (1)
│ │ │ │ -934D6   UID Size            04 (4)
│ │ │ │ -934D7   UID                 00000000 (0)
│ │ │ │ -934DB   GID Size            04 (4)
│ │ │ │ -934DC   GID                 00000000 (0)
│ │ │ │ -934E0 PAYLOAD
│ │ │ │ -
│ │ │ │ -9493E LOCAL HEADER #86      04034B50 (67324752)
│ │ │ │ -94942 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -94943 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -94944 General Purpose Flag  0000 (0)
│ │ │ │ -94946 Compression Method    0000 (0) 'Stored'
│ │ │ │ -94948 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9494C CRC                   5E9E64F1 (1587438833)
│ │ │ │ -94950 Compressed Size       000008EC (2284)
│ │ │ │ -94954 Uncompressed Size     000008EC (2284)
│ │ │ │ -94958 Filename Length       0016 (22)
│ │ │ │ -9495A Extra Length          001C (28)
│ │ │ │ -9495C Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9495C: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -94972 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -94974   Length              0009 (9)
│ │ │ │ -94976   Flags               03 (3) 'Modification Access'
│ │ │ │ -94977   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9497B   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9497F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -94981   Length              000B (11)
│ │ │ │ -94983   Version             01 (1)
│ │ │ │ -94984   UID Size            04 (4)
│ │ │ │ -94985   UID                 00000000 (0)
│ │ │ │ -94989   GID Size            04 (4)
│ │ │ │ -9498A   GID                 00000000 (0)
│ │ │ │ -9498E PAYLOAD
│ │ │ │ -
│ │ │ │ -9527A LOCAL HEADER #87      04034B50 (67324752)
│ │ │ │ -9527E Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9527F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -95280 General Purpose Flag  0000 (0)
│ │ │ │ -95282 Compression Method    0000 (0) 'Stored'
│ │ │ │ -95284 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -95288 CRC                   42E340AB (1122189483)
│ │ │ │ -9528C Compressed Size       00001F2E (7982)
│ │ │ │ -95290 Uncompressed Size     00001F2E (7982)
│ │ │ │ -95294 Filename Length       001E (30)
│ │ │ │ -95296 Extra Length          001C (28)
│ │ │ │ -95298 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x95298: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -952B6 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -952B8   Length              0009 (9)
│ │ │ │ -952BA   Flags               03 (3) 'Modification Access'
│ │ │ │ -952BB   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -952BF   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -952C3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -952C5   Length              000B (11)
│ │ │ │ -952C7   Version             01 (1)
│ │ │ │ -952C8   UID Size            04 (4)
│ │ │ │ -952C9   UID                 00000000 (0)
│ │ │ │ -952CD   GID Size            04 (4)
│ │ │ │ -952CE   GID                 00000000 (0)
│ │ │ │ -952D2 PAYLOAD
│ │ │ │ -
│ │ │ │ -97200 LOCAL HEADER #88      04034B50 (67324752)
│ │ │ │ -97204 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -97205 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -97206 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -97208 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9720A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9720E CRC                   46D4ADFC (1188343292)
│ │ │ │ -97212 Compressed Size       00003D71 (15729)
│ │ │ │ -97216 Uncompressed Size     00016649 (91721)
│ │ │ │ -9721A Filename Length       001A (26)
│ │ │ │ -9721C Extra Length          001C (28)
│ │ │ │ -9721E Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9721E: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -97238 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9723A   Length              0009 (9)
│ │ │ │ -9723C   Flags               03 (3) 'Modification Access'
│ │ │ │ -9723D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -97241   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -97245 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -97247   Length              000B (11)
│ │ │ │ -97249   Version             01 (1)
│ │ │ │ -9724A   UID Size            04 (4)
│ │ │ │ -9724B   UID                 00000000 (0)
│ │ │ │ -9724F   GID Size            04 (4)
│ │ │ │ -97250   GID                 00000000 (0)
│ │ │ │ -97254 PAYLOAD
│ │ │ │ -
│ │ │ │ -9AFC5 LOCAL HEADER #89      04034B50 (67324752)
│ │ │ │ -9AFC9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9AFCA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9AFCB General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9AFCD Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9AFCF Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9AFD3 CRC                   228F80DD (579829981)
│ │ │ │ -9AFD7 Compressed Size       000029BF (10687)
│ │ │ │ -9AFDB Uncompressed Size     0000BA6A (47722)
│ │ │ │ -9AFDF Filename Length       0018 (24)
│ │ │ │ -9AFE1 Extra Length          001C (28)
│ │ │ │ -9AFE3 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9AFE3: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9AFFB Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9AFFD   Length              0009 (9)
│ │ │ │ -9AFFF   Flags               03 (3) 'Modification Access'
│ │ │ │ -9B000   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9B004   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9B008 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9B00A   Length              000B (11)
│ │ │ │ -9B00C   Version             01 (1)
│ │ │ │ -9B00D   UID Size            04 (4)
│ │ │ │ -9B00E   UID                 00000000 (0)
│ │ │ │ -9B012   GID Size            04 (4)
│ │ │ │ -9B013   GID                 00000000 (0)
│ │ │ │ -9B017 PAYLOAD
│ │ │ │ -
│ │ │ │ -9D9D6 LOCAL HEADER #90      04034B50 (67324752)
│ │ │ │ -9D9DA Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9D9DB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9D9DC General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9D9DE Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9D9E0 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9D9E4 CRC                   DCB3B516 (3702764822)
│ │ │ │ -9D9E8 Compressed Size       000000AE (174)
│ │ │ │ -9D9EC Uncompressed Size     000000FC (252)
│ │ │ │ -9D9F0 Filename Length       0016 (22)
│ │ │ │ -9D9F2 Extra Length          001C (28)
│ │ │ │ -9D9F4 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9D9F4: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DA0A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DA0C   Length              0009 (9)
│ │ │ │ -9DA0E   Flags               03 (3) 'Modification Access'
│ │ │ │ -9DA0F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DA13   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DA17 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DA19   Length              000B (11)
│ │ │ │ -9DA1B   Version             01 (1)
│ │ │ │ -9DA1C   UID Size            04 (4)
│ │ │ │ -9DA1D   UID                 00000000 (0)
│ │ │ │ -9DA21   GID Size            04 (4)
│ │ │ │ -9DA22   GID                 00000000 (0)
│ │ │ │ -9DA26 PAYLOAD               XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
│ │ │ │ +04B61 LOCAL HEADER #5       04034B50 (67324752)
│ │ │ │ +04B65 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +04B66 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +04B67 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +04B69 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +04B6B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +04B6F CRC                   B8F4A452 (3103040594)
│ │ │ │ +04B73 Compressed Size       000003F0 (1008)
│ │ │ │ +04B77 Uncompressed Size     00000876 (2166)
│ │ │ │ +04B7B Filename Length       0014 (20)
│ │ │ │ +04B7D Extra Length          001C (28)
│ │ │ │ +04B7F Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4B7F: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +04B93 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +04B95   Length              0009 (9)
│ │ │ │ +04B97   Flags               03 (3) 'Modification Access'
│ │ │ │ +04B98   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +04B9C   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +04BA0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +04BA2   Length              000B (11)
│ │ │ │ +04BA4   Version             01 (1)
│ │ │ │ +04BA5   UID Size            04 (4)
│ │ │ │ +04BA6   UID                 00000000 (0)
│ │ │ │ +04BAA   GID Size            04 (4)
│ │ │ │ +04BAB   GID                 00000000 (0)
│ │ │ │ +04BAF PAYLOAD
│ │ │ │ +
│ │ │ │ +04F9F LOCAL HEADER #6       04034B50 (67324752)
│ │ │ │ +04FA3 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +04FA4 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +04FA5 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +04FA7 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +04FA9 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +04FAD CRC                   D32DA388 (3542983560)
│ │ │ │ +04FB1 Compressed Size       000001AE (430)
│ │ │ │ +04FB5 Uncompressed Size     000002FC (764)
│ │ │ │ +04FB9 Filename Length       0011 (17)
│ │ │ │ +04FBB Extra Length          001C (28)
│ │ │ │ +04FBD Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4FBD: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +04FCE Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +04FD0   Length              0009 (9)
│ │ │ │ +04FD2   Flags               03 (3) 'Modification Access'
│ │ │ │ +04FD3   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +04FD7   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +04FDB Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +04FDD   Length              000B (11)
│ │ │ │ +04FDF   Version             01 (1)
│ │ │ │ +04FE0   UID Size            04 (4)
│ │ │ │ +04FE1   UID                 00000000 (0)
│ │ │ │ +04FE5   GID Size            04 (4)
│ │ │ │ +04FE6   GID                 00000000 (0)
│ │ │ │ +04FEA PAYLOAD
│ │ │ │ +
│ │ │ │ +05198 LOCAL HEADER #7       04034B50 (67324752)
│ │ │ │ +0519C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +0519D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +0519E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +051A0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +051A2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +051A6 CRC                   BD3875EC (3174594028)
│ │ │ │ +051AA Compressed Size       000020C4 (8388)
│ │ │ │ +051AE Uncompressed Size     0000B4B0 (46256)
│ │ │ │ +051B2 Filename Length       001B (27)
│ │ │ │ +051B4 Extra Length          001C (28)
│ │ │ │ +051B6 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x51B6: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +051D1 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +051D3   Length              0009 (9)
│ │ │ │ +051D5   Flags               03 (3) 'Modification Access'
│ │ │ │ +051D6   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +051DA   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +051DE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +051E0   Length              000B (11)
│ │ │ │ +051E2   Version             01 (1)
│ │ │ │ +051E3   UID Size            04 (4)
│ │ │ │ +051E4   UID                 00000000 (0)
│ │ │ │ +051E8   GID Size            04 (4)
│ │ │ │ +051E9   GID                 00000000 (0)
│ │ │ │ +051ED PAYLOAD
│ │ │ │ +
│ │ │ │ +072B1 LOCAL HEADER #8       04034B50 (67324752)
│ │ │ │ +072B5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +072B6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +072B7 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +072B9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +072BB Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +072BF CRC                   CB35CCED (3409300717)
│ │ │ │ +072C3 Compressed Size       00000E6F (3695)
│ │ │ │ +072C7 Uncompressed Size     000030B2 (12466)
│ │ │ │ +072CB Filename Length       001D (29)
│ │ │ │ +072CD Extra Length          001C (28)
│ │ │ │ +072CF Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x72CF: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +072EC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +072EE   Length              0009 (9)
│ │ │ │ +072F0   Flags               03 (3) 'Modification Access'
│ │ │ │ +072F1   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +072F5   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +072F9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +072FB   Length              000B (11)
│ │ │ │ +072FD   Version             01 (1)
│ │ │ │ +072FE   UID Size            04 (4)
│ │ │ │ +072FF   UID                 00000000 (0)
│ │ │ │ +07303   GID Size            04 (4)
│ │ │ │ +07304   GID                 00000000 (0)
│ │ │ │ +07308 PAYLOAD
│ │ │ │ +
│ │ │ │ +08177 LOCAL HEADER #9       04034B50 (67324752)
│ │ │ │ +0817B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +0817C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +0817D General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +0817F Compression Method    0008 (8) 'Deflated'
│ │ │ │ +08181 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +08185 CRC                   D01F57B3 (3491714995)
│ │ │ │ +08189 Compressed Size       00000972 (2418)
│ │ │ │ +0818D Uncompressed Size     00001CB2 (7346)
│ │ │ │ +08191 Filename Length       0019 (25)
│ │ │ │ +08193 Extra Length          001C (28)
│ │ │ │ +08195 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x8195: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +081AE Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +081B0   Length              0009 (9)
│ │ │ │ +081B2   Flags               03 (3) 'Modification Access'
│ │ │ │ +081B3   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +081B7   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +081BB Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +081BD   Length              000B (11)
│ │ │ │ +081BF   Version             01 (1)
│ │ │ │ +081C0   UID Size            04 (4)
│ │ │ │ +081C1   UID                 00000000 (0)
│ │ │ │ +081C5   GID Size            04 (4)
│ │ │ │ +081C6   GID                 00000000 (0)
│ │ │ │ +081CA PAYLOAD
│ │ │ │ +
│ │ │ │ +08B3C LOCAL HEADER #10      04034B50 (67324752)
│ │ │ │ +08B40 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +08B41 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +08B42 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +08B44 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +08B46 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +08B4A CRC                   8FE86D92 (2414374290)
│ │ │ │ +08B4E Compressed Size       00003880 (14464)
│ │ │ │ +08B52 Uncompressed Size     0000F7F4 (63476)
│ │ │ │ +08B56 Filename Length       0015 (21)
│ │ │ │ +08B58 Extra Length          001C (28)
│ │ │ │ +08B5A Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x8B5A: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +08B6F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +08B71   Length              0009 (9)
│ │ │ │ +08B73   Flags               03 (3) 'Modification Access'
│ │ │ │ +08B74   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +08B78   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +08B7C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +08B7E   Length              000B (11)
│ │ │ │ +08B80   Version             01 (1)
│ │ │ │ +08B81   UID Size            04 (4)
│ │ │ │ +08B82   UID                 00000000 (0)
│ │ │ │ +08B86   GID Size            04 (4)
│ │ │ │ +08B87   GID                 00000000 (0)
│ │ │ │ +08B8B PAYLOAD
│ │ │ │ +
│ │ │ │ +0C40B LOCAL HEADER #11      04034B50 (67324752)
│ │ │ │ +0C40F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +0C410 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +0C411 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +0C413 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +0C415 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +0C419 CRC                   5D10F8D5 (1561393365)
│ │ │ │ +0C41D Compressed Size       0000AAE5 (43749)
│ │ │ │ +0C421 Uncompressed Size     0003DFDE (253918)
│ │ │ │ +0C425 Filename Length       0012 (18)
│ │ │ │ +0C427 Extra Length          001C (28)
│ │ │ │ +0C429 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0xC429: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +0C43B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +0C43D   Length              0009 (9)
│ │ │ │ +0C43F   Flags               03 (3) 'Modification Access'
│ │ │ │ +0C440   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +0C444   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +0C448 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +0C44A   Length              000B (11)
│ │ │ │ +0C44C   Version             01 (1)
│ │ │ │ +0C44D   UID Size            04 (4)
│ │ │ │ +0C44E   UID                 00000000 (0)
│ │ │ │ +0C452   GID Size            04 (4)
│ │ │ │ +0C453   GID                 00000000 (0)
│ │ │ │ +0C457 PAYLOAD
│ │ │ │ +
│ │ │ │ +16F3C LOCAL HEADER #12      04034B50 (67324752)
│ │ │ │ +16F40 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +16F41 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +16F42 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +16F44 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +16F46 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +16F4A CRC                   55F94B52 (1442401106)
│ │ │ │ +16F4E Compressed Size       00003B1D (15133)
│ │ │ │ +16F52 Uncompressed Size     0001B2A0 (111264)
│ │ │ │ +16F56 Filename Length       0015 (21)
│ │ │ │ +16F58 Extra Length          001C (28)
│ │ │ │ +16F5A Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x16F5A: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +16F6F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +16F71   Length              0009 (9)
│ │ │ │ +16F73   Flags               03 (3) 'Modification Access'
│ │ │ │ +16F74   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +16F78   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +16F7C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +16F7E   Length              000B (11)
│ │ │ │ +16F80   Version             01 (1)
│ │ │ │ +16F81   UID Size            04 (4)
│ │ │ │ +16F82   UID                 00000000 (0)
│ │ │ │ +16F86   GID Size            04 (4)
│ │ │ │ +16F87   GID                 00000000 (0)
│ │ │ │ +16F8B PAYLOAD
│ │ │ │ +
│ │ │ │ +1AAA8 LOCAL HEADER #13      04034B50 (67324752)
│ │ │ │ +1AAAC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +1AAAD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +1AAAE General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +1AAB0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +1AAB2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +1AAB6 CRC                   C8304069 (3358605417)
│ │ │ │ +1AABA Compressed Size       00009082 (36994)
│ │ │ │ +1AABE Uncompressed Size     0003D05F (249951)
│ │ │ │ +1AAC2 Filename Length       0014 (20)
│ │ │ │ +1AAC4 Extra Length          001C (28)
│ │ │ │ +1AAC6 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x1AAC6: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +1AADA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +1AADC   Length              0009 (9)
│ │ │ │ +1AADE   Flags               03 (3) 'Modification Access'
│ │ │ │ +1AADF   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +1AAE3   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +1AAE7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +1AAE9   Length              000B (11)
│ │ │ │ +1AAEB   Version             01 (1)
│ │ │ │ +1AAEC   UID Size            04 (4)
│ │ │ │ +1AAED   UID                 00000000 (0)
│ │ │ │ +1AAF1   GID Size            04 (4)
│ │ │ │ +1AAF2   GID                 00000000 (0)
│ │ │ │ +1AAF6 PAYLOAD
│ │ │ │ +
│ │ │ │ +23B78 LOCAL HEADER #14      04034B50 (67324752)
│ │ │ │ +23B7C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +23B7D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +23B7E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +23B80 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +23B82 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +23B86 CRC                   2482A8C2 (612542658)
│ │ │ │ +23B8A Compressed Size       00002A67 (10855)
│ │ │ │ +23B8E Uncompressed Size     0001151F (70943)
│ │ │ │ +23B92 Filename Length       0016 (22)
│ │ │ │ +23B94 Extra Length          001C (28)
│ │ │ │ +23B96 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x23B96: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +23BAC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +23BAE   Length              0009 (9)
│ │ │ │ +23BB0   Flags               03 (3) 'Modification Access'
│ │ │ │ +23BB1   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +23BB5   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +23BB9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +23BBB   Length              000B (11)
│ │ │ │ +23BBD   Version             01 (1)
│ │ │ │ +23BBE   UID Size            04 (4)
│ │ │ │ +23BBF   UID                 00000000 (0)
│ │ │ │ +23BC3   GID Size            04 (4)
│ │ │ │ +23BC4   GID                 00000000 (0)
│ │ │ │ +23BC8 PAYLOAD
│ │ │ │ +
│ │ │ │ +2662F LOCAL HEADER #15      04034B50 (67324752)
│ │ │ │ +26633 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +26634 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +26635 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +26637 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +26639 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2663D CRC                   29636121 (694378785)
│ │ │ │ +26641 Compressed Size       000014DA (5338)
│ │ │ │ +26645 Uncompressed Size     00005176 (20854)
│ │ │ │ +26649 Filename Length       001D (29)
│ │ │ │ +2664B Extra Length          001C (28)
│ │ │ │ +2664D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x2664D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +2666A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +2666C   Length              0009 (9)
│ │ │ │ +2666E   Flags               03 (3) 'Modification Access'
│ │ │ │ +2666F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +26673   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +26677 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +26679   Length              000B (11)
│ │ │ │ +2667B   Version             01 (1)
│ │ │ │ +2667C   UID Size            04 (4)
│ │ │ │ +2667D   UID                 00000000 (0)
│ │ │ │ +26681   GID Size            04 (4)
│ │ │ │ +26682   GID                 00000000 (0)
│ │ │ │ +26686 PAYLOAD
│ │ │ │ +
│ │ │ │ +27B60 LOCAL HEADER #16      04034B50 (67324752)
│ │ │ │ +27B64 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +27B65 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +27B66 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +27B68 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +27B6A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +27B6E CRC                   298D1A65 (697113189)
│ │ │ │ +27B72 Compressed Size       000037FC (14332)
│ │ │ │ +27B76 Uncompressed Size     0000E9F0 (59888)
│ │ │ │ +27B7A Filename Length       001C (28)
│ │ │ │ +27B7C Extra Length          001C (28)
│ │ │ │ +27B7E Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x27B7E: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +27B9A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +27B9C   Length              0009 (9)
│ │ │ │ +27B9E   Flags               03 (3) 'Modification Access'
│ │ │ │ +27B9F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +27BA3   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +27BA7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +27BA9   Length              000B (11)
│ │ │ │ +27BAB   Version             01 (1)
│ │ │ │ +27BAC   UID Size            04 (4)
│ │ │ │ +27BAD   UID                 00000000 (0)
│ │ │ │ +27BB1   GID Size            04 (4)
│ │ │ │ +27BB2   GID                 00000000 (0)
│ │ │ │ +27BB6 PAYLOAD
│ │ │ │ +
│ │ │ │ +2B3B2 LOCAL HEADER #17      04034B50 (67324752)
│ │ │ │ +2B3B6 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +2B3B7 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +2B3B8 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +2B3BA Compression Method    0008 (8) 'Deflated'
│ │ │ │ +2B3BC Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2B3C0 CRC                   6A63C5E7 (1784923623)
│ │ │ │ +2B3C4 Compressed Size       000006A0 (1696)
│ │ │ │ +2B3C8 Uncompressed Size     000011F4 (4596)
│ │ │ │ +2B3CC Filename Length       001C (28)
│ │ │ │ +2B3CE Extra Length          001C (28)
│ │ │ │ +2B3D0 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x2B3D0: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +2B3EC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +2B3EE   Length              0009 (9)
│ │ │ │ +2B3F0   Flags               03 (3) 'Modification Access'
│ │ │ │ +2B3F1   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2B3F5   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2B3F9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +2B3FB   Length              000B (11)
│ │ │ │ +2B3FD   Version             01 (1)
│ │ │ │ +2B3FE   UID Size            04 (4)
│ │ │ │ +2B3FF   UID                 00000000 (0)
│ │ │ │ +2B403   GID Size            04 (4)
│ │ │ │ +2B404   GID                 00000000 (0)
│ │ │ │ +2B408 PAYLOAD
│ │ │ │ +
│ │ │ │ +2BAA8 LOCAL HEADER #18      04034B50 (67324752)
│ │ │ │ +2BAAC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +2BAAD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +2BAAE General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +2BAB0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +2BAB2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2BAB6 CRC                   F6FDE277 (4143833719)
│ │ │ │ +2BABA Compressed Size       0000107C (4220)
│ │ │ │ +2BABE Uncompressed Size     00004BFF (19455)
│ │ │ │ +2BAC2 Filename Length       001B (27)
│ │ │ │ +2BAC4 Extra Length          001C (28)
│ │ │ │ +2BAC6 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x2BAC6: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +2BAE1 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +2BAE3   Length              0009 (9)
│ │ │ │ +2BAE5   Flags               03 (3) 'Modification Access'
│ │ │ │ +2BAE6   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2BAEA   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2BAEE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +2BAF0   Length              000B (11)
│ │ │ │ +2BAF2   Version             01 (1)
│ │ │ │ +2BAF3   UID Size            04 (4)
│ │ │ │ +2BAF4   UID                 00000000 (0)
│ │ │ │ +2BAF8   GID Size            04 (4)
│ │ │ │ +2BAF9   GID                 00000000 (0)
│ │ │ │ +2BAFD PAYLOAD
│ │ │ │ +
│ │ │ │ +2CB79 LOCAL HEADER #19      04034B50 (67324752)
│ │ │ │ +2CB7D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +2CB7E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +2CB7F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +2CB81 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +2CB83 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2CB87 CRC                   8F81EFC3 (2407657411)
│ │ │ │ +2CB8B Compressed Size       000033AB (13227)
│ │ │ │ +2CB8F Uncompressed Size     0000BC94 (48276)
│ │ │ │ +2CB93 Filename Length       001D (29)
│ │ │ │ +2CB95 Extra Length          001C (28)
│ │ │ │ +2CB97 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x2CB97: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +2CBB4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +2CBB6   Length              0009 (9)
│ │ │ │ +2CBB8   Flags               03 (3) 'Modification Access'
│ │ │ │ +2CBB9   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2CBBD   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2CBC1 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +2CBC3   Length              000B (11)
│ │ │ │ +2CBC5   Version             01 (1)
│ │ │ │ +2CBC6   UID Size            04 (4)
│ │ │ │ +2CBC7   UID                 00000000 (0)
│ │ │ │ +2CBCB   GID Size            04 (4)
│ │ │ │ +2CBCC   GID                 00000000 (0)
│ │ │ │ +2CBD0 PAYLOAD
│ │ │ │ +
│ │ │ │ +2FF7B LOCAL HEADER #20      04034B50 (67324752)
│ │ │ │ +2FF7F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +2FF80 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +2FF81 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +2FF83 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +2FF85 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2FF89 CRC                   F6188119 (4128801049)
│ │ │ │ +2FF8D Compressed Size       00000D6B (3435)
│ │ │ │ +2FF91 Uncompressed Size     00003876 (14454)
│ │ │ │ +2FF95 Filename Length       001D (29)
│ │ │ │ +2FF97 Extra Length          001C (28)
│ │ │ │ +2FF99 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x2FF99: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +2FFB6 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +2FFB8   Length              0009 (9)
│ │ │ │ +2FFBA   Flags               03 (3) 'Modification Access'
│ │ │ │ +2FFBB   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2FFBF   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +2FFC3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +2FFC5   Length              000B (11)
│ │ │ │ +2FFC7   Version             01 (1)
│ │ │ │ +2FFC8   UID Size            04 (4)
│ │ │ │ +2FFC9   UID                 00000000 (0)
│ │ │ │ +2FFCD   GID Size            04 (4)
│ │ │ │ +2FFCE   GID                 00000000 (0)
│ │ │ │ +2FFD2 PAYLOAD
│ │ │ │ +
│ │ │ │ +30D3D LOCAL HEADER #21      04034B50 (67324752)
│ │ │ │ +30D41 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +30D42 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +30D43 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +30D45 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +30D47 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +30D4B CRC                   39EA28E4 (971647204)
│ │ │ │ +30D4F Compressed Size       00001C6C (7276)
│ │ │ │ +30D53 Uncompressed Size     0000C186 (49542)
│ │ │ │ +30D57 Filename Length       001A (26)
│ │ │ │ +30D59 Extra Length          001C (28)
│ │ │ │ +30D5B Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x30D5B: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +30D75 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +30D77   Length              0009 (9)
│ │ │ │ +30D79   Flags               03 (3) 'Modification Access'
│ │ │ │ +30D7A   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +30D7E   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +30D82 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +30D84   Length              000B (11)
│ │ │ │ +30D86   Version             01 (1)
│ │ │ │ +30D87   UID Size            04 (4)
│ │ │ │ +30D88   UID                 00000000 (0)
│ │ │ │ +30D8C   GID Size            04 (4)
│ │ │ │ +30D8D   GID                 00000000 (0)
│ │ │ │ +30D91 PAYLOAD
│ │ │ │ +
│ │ │ │ +329FD LOCAL HEADER #22      04034B50 (67324752)
│ │ │ │ +32A01 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +32A02 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +32A03 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +32A05 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +32A07 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +32A0B CRC                   65574916 (1700219158)
│ │ │ │ +32A0F Compressed Size       000003A3 (931)
│ │ │ │ +32A13 Uncompressed Size     0000088E (2190)
│ │ │ │ +32A17 Filename Length       0012 (18)
│ │ │ │ +32A19 Extra Length          001C (28)
│ │ │ │ +32A1B Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x32A1B: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +32A2D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +32A2F   Length              0009 (9)
│ │ │ │ +32A31   Flags               03 (3) 'Modification Access'
│ │ │ │ +32A32   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +32A36   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +32A3A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +32A3C   Length              000B (11)
│ │ │ │ +32A3E   Version             01 (1)
│ │ │ │ +32A3F   UID Size            04 (4)
│ │ │ │ +32A40   UID                 00000000 (0)
│ │ │ │ +32A44   GID Size            04 (4)
│ │ │ │ +32A45   GID                 00000000 (0)
│ │ │ │ +32A49 PAYLOAD
│ │ │ │ +
│ │ │ │ +32DEC LOCAL HEADER #23      04034B50 (67324752)
│ │ │ │ +32DF0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +32DF1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +32DF2 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +32DF4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +32DF6 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +32DFA CRC                   83472134 (2202476852)
│ │ │ │ +32DFE Compressed Size       000001D4 (468)
│ │ │ │ +32E02 Uncompressed Size     00000311 (785)
│ │ │ │ +32E06 Filename Length       0020 (32)
│ │ │ │ +32E08 Extra Length          001C (28)
│ │ │ │ +32E0A Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x32E0A: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +32E2A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +32E2C   Length              0009 (9)
│ │ │ │ +32E2E   Flags               03 (3) 'Modification Access'
│ │ │ │ +32E2F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +32E33   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +32E37 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +32E39   Length              000B (11)
│ │ │ │ +32E3B   Version             01 (1)
│ │ │ │ +32E3C   UID Size            04 (4)
│ │ │ │ +32E3D   UID                 00000000 (0)
│ │ │ │ +32E41   GID Size            04 (4)
│ │ │ │ +32E42   GID                 00000000 (0)
│ │ │ │ +32E46 PAYLOAD
│ │ │ │ +
│ │ │ │ +3301A LOCAL HEADER #24      04034B50 (67324752)
│ │ │ │ +3301E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +3301F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +33020 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +33022 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +33024 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +33028 CRC                   97D21429 (2547127337)
│ │ │ │ +3302C Compressed Size       000017AA (6058)
│ │ │ │ +33030 Uncompressed Size     00009CD3 (40147)
│ │ │ │ +33034 Filename Length       001B (27)
│ │ │ │ +33036 Extra Length          001C (28)
│ │ │ │ +33038 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x33038: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +33053 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +33055   Length              0009 (9)
│ │ │ │ +33057   Flags               03 (3) 'Modification Access'
│ │ │ │ +33058   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3305C   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +33060 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +33062   Length              000B (11)
│ │ │ │ +33064   Version             01 (1)
│ │ │ │ +33065   UID Size            04 (4)
│ │ │ │ +33066   UID                 00000000 (0)
│ │ │ │ +3306A   GID Size            04 (4)
│ │ │ │ +3306B   GID                 00000000 (0)
│ │ │ │ +3306F PAYLOAD
│ │ │ │ +
│ │ │ │ +34819 LOCAL HEADER #25      04034B50 (67324752)
│ │ │ │ +3481D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +3481E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +3481F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +34821 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +34823 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +34827 CRC                   5F73B5AE (1601418670)
│ │ │ │ +3482B Compressed Size       00001371 (4977)
│ │ │ │ +3482F Uncompressed Size     00003B66 (15206)
│ │ │ │ +34833 Filename Length       0015 (21)
│ │ │ │ +34835 Extra Length          001C (28)
│ │ │ │ +34837 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x34837: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +3484C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +3484E   Length              0009 (9)
│ │ │ │ +34850   Flags               03 (3) 'Modification Access'
│ │ │ │ +34851   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +34855   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +34859 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +3485B   Length              000B (11)
│ │ │ │ +3485D   Version             01 (1)
│ │ │ │ +3485E   UID Size            04 (4)
│ │ │ │ +3485F   UID                 00000000 (0)
│ │ │ │ +34863   GID Size            04 (4)
│ │ │ │ +34864   GID                 00000000 (0)
│ │ │ │ +34868 PAYLOAD
│ │ │ │ +
│ │ │ │ +35BD9 LOCAL HEADER #26      04034B50 (67324752)
│ │ │ │ +35BDD Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +35BDE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +35BDF General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +35BE1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +35BE3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +35BE7 CRC                   7FAE09B6 (2142112182)
│ │ │ │ +35BEB Compressed Size       00000AD1 (2769)
│ │ │ │ +35BEF Uncompressed Size     00002135 (8501)
│ │ │ │ +35BF3 Filename Length       0011 (17)
│ │ │ │ +35BF5 Extra Length          001C (28)
│ │ │ │ +35BF7 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x35BF7: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +35C08 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +35C0A   Length              0009 (9)
│ │ │ │ +35C0C   Flags               03 (3) 'Modification Access'
│ │ │ │ +35C0D   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +35C11   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +35C15 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +35C17   Length              000B (11)
│ │ │ │ +35C19   Version             01 (1)
│ │ │ │ +35C1A   UID Size            04 (4)
│ │ │ │ +35C1B   UID                 00000000 (0)
│ │ │ │ +35C1F   GID Size            04 (4)
│ │ │ │ +35C20   GID                 00000000 (0)
│ │ │ │ +35C24 PAYLOAD
│ │ │ │ +
│ │ │ │ +366F5 LOCAL HEADER #27      04034B50 (67324752)
│ │ │ │ +366F9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +366FA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +366FB General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +366FD Compression Method    0008 (8) 'Deflated'
│ │ │ │ +366FF Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +36703 CRC                   4CCDDBC1 (1288559553)
│ │ │ │ +36707 Compressed Size       000003FE (1022)
│ │ │ │ +3670B Uncompressed Size     00000E99 (3737)
│ │ │ │ +3670F Filename Length       0014 (20)
│ │ │ │ +36711 Extra Length          001C (28)
│ │ │ │ +36713 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x36713: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +36727 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +36729   Length              0009 (9)
│ │ │ │ +3672B   Flags               03 (3) 'Modification Access'
│ │ │ │ +3672C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +36730   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +36734 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +36736   Length              000B (11)
│ │ │ │ +36738   Version             01 (1)
│ │ │ │ +36739   UID Size            04 (4)
│ │ │ │ +3673A   UID                 00000000 (0)
│ │ │ │ +3673E   GID Size            04 (4)
│ │ │ │ +3673F   GID                 00000000 (0)
│ │ │ │ +36743 PAYLOAD
│ │ │ │ +
│ │ │ │ +36B41 LOCAL HEADER #28      04034B50 (67324752)
│ │ │ │ +36B45 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +36B46 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +36B47 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +36B49 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +36B4B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +36B4F CRC                   EB83ACB7 (3951275191)
│ │ │ │ +36B53 Compressed Size       00001261 (4705)
│ │ │ │ +36B57 Uncompressed Size     00003469 (13417)
│ │ │ │ +36B5B Filename Length       0014 (20)
│ │ │ │ +36B5D Extra Length          001C (28)
│ │ │ │ +36B5F Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x36B5F: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +36B73 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +36B75   Length              0009 (9)
│ │ │ │ +36B77   Flags               03 (3) 'Modification Access'
│ │ │ │ +36B78   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +36B7C   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +36B80 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +36B82   Length              000B (11)
│ │ │ │ +36B84   Version             01 (1)
│ │ │ │ +36B85   UID Size            04 (4)
│ │ │ │ +36B86   UID                 00000000 (0)
│ │ │ │ +36B8A   GID Size            04 (4)
│ │ │ │ +36B8B   GID                 00000000 (0)
│ │ │ │ +36B8F PAYLOAD
│ │ │ │ +
│ │ │ │ +37DF0 LOCAL HEADER #29      04034B50 (67324752)
│ │ │ │ +37DF4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +37DF5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +37DF6 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +37DF8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +37DFA Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +37DFE CRC                   95A9A82D (2510923821)
│ │ │ │ +37E02 Compressed Size       00000ACF (2767)
│ │ │ │ +37E06 Uncompressed Size     000022FF (8959)
│ │ │ │ +37E0A Filename Length       001B (27)
│ │ │ │ +37E0C Extra Length          001C (28)
│ │ │ │ +37E0E Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x37E0E: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +37E29 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +37E2B   Length              0009 (9)
│ │ │ │ +37E2D   Flags               03 (3) 'Modification Access'
│ │ │ │ +37E2E   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +37E32   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +37E36 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +37E38   Length              000B (11)
│ │ │ │ +37E3A   Version             01 (1)
│ │ │ │ +37E3B   UID Size            04 (4)
│ │ │ │ +37E3C   UID                 00000000 (0)
│ │ │ │ +37E40   GID Size            04 (4)
│ │ │ │ +37E41   GID                 00000000 (0)
│ │ │ │ +37E45 PAYLOAD
│ │ │ │ +
│ │ │ │ +38914 LOCAL HEADER #30      04034B50 (67324752)
│ │ │ │ +38918 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +38919 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +3891A General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +3891C Compression Method    0008 (8) 'Deflated'
│ │ │ │ +3891E Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +38922 CRC                   160B7E11 (369851921)
│ │ │ │ +38926 Compressed Size       00000A8F (2703)
│ │ │ │ +3892A Uncompressed Size     0000237A (9082)
│ │ │ │ +3892E Filename Length       0013 (19)
│ │ │ │ +38930 Extra Length          001C (28)
│ │ │ │ +38932 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x38932: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +38945 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +38947   Length              0009 (9)
│ │ │ │ +38949   Flags               03 (3) 'Modification Access'
│ │ │ │ +3894A   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3894E   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +38952 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +38954   Length              000B (11)
│ │ │ │ +38956   Version             01 (1)
│ │ │ │ +38957   UID Size            04 (4)
│ │ │ │ +38958   UID                 00000000 (0)
│ │ │ │ +3895C   GID Size            04 (4)
│ │ │ │ +3895D   GID                 00000000 (0)
│ │ │ │ +38961 PAYLOAD
│ │ │ │ +
│ │ │ │ +393F0 LOCAL HEADER #31      04034B50 (67324752)
│ │ │ │ +393F4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +393F5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +393F6 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +393F8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +393FA Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +393FE CRC                   813C96AD (2168231597)
│ │ │ │ +39402 Compressed Size       00000F45 (3909)
│ │ │ │ +39406 Uncompressed Size     000036F1 (14065)
│ │ │ │ +3940A Filename Length       000F (15)
│ │ │ │ +3940C Extra Length          001C (28)
│ │ │ │ +3940E Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x3940E: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +3941D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +3941F   Length              0009 (9)
│ │ │ │ +39421   Flags               03 (3) 'Modification Access'
│ │ │ │ +39422   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +39426   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3942A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +3942C   Length              000B (11)
│ │ │ │ +3942E   Version             01 (1)
│ │ │ │ +3942F   UID Size            04 (4)
│ │ │ │ +39430   UID                 00000000 (0)
│ │ │ │ +39434   GID Size            04 (4)
│ │ │ │ +39435   GID                 00000000 (0)
│ │ │ │ +39439 PAYLOAD
│ │ │ │ +
│ │ │ │ +3A37E LOCAL HEADER #32      04034B50 (67324752)
│ │ │ │ +3A382 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +3A383 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +3A384 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +3A386 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +3A388 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3A38C CRC                   54672E6E (1416048238)
│ │ │ │ +3A390 Compressed Size       0000066A (1642)
│ │ │ │ +3A394 Uncompressed Size     000018DF (6367)
│ │ │ │ +3A398 Filename Length       000F (15)
│ │ │ │ +3A39A Extra Length          001C (28)
│ │ │ │ +3A39C Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x3A39C: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +3A3AB Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +3A3AD   Length              0009 (9)
│ │ │ │ +3A3AF   Flags               03 (3) 'Modification Access'
│ │ │ │ +3A3B0   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3A3B4   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3A3B8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +3A3BA   Length              000B (11)
│ │ │ │ +3A3BC   Version             01 (1)
│ │ │ │ +3A3BD   UID Size            04 (4)
│ │ │ │ +3A3BE   UID                 00000000 (0)
│ │ │ │ +3A3C2   GID Size            04 (4)
│ │ │ │ +3A3C3   GID                 00000000 (0)
│ │ │ │ +3A3C7 PAYLOAD
│ │ │ │ +
│ │ │ │ +3AA31 LOCAL HEADER #33      04034B50 (67324752)
│ │ │ │ +3AA35 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +3AA36 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +3AA37 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +3AA39 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +3AA3B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3AA3F CRC                   71733BC2 (1903377346)
│ │ │ │ +3AA43 Compressed Size       00001A48 (6728)
│ │ │ │ +3AA47 Uncompressed Size     000064F2 (25842)
│ │ │ │ +3AA4B Filename Length       0013 (19)
│ │ │ │ +3AA4D Extra Length          001C (28)
│ │ │ │ +3AA4F Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x3AA4F: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +3AA62 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +3AA64   Length              0009 (9)
│ │ │ │ +3AA66   Flags               03 (3) 'Modification Access'
│ │ │ │ +3AA67   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3AA6B   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3AA6F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +3AA71   Length              000B (11)
│ │ │ │ +3AA73   Version             01 (1)
│ │ │ │ +3AA74   UID Size            04 (4)
│ │ │ │ +3AA75   UID                 00000000 (0)
│ │ │ │ +3AA79   GID Size            04 (4)
│ │ │ │ +3AA7A   GID                 00000000 (0)
│ │ │ │ +3AA7E PAYLOAD
│ │ │ │ +
│ │ │ │ +3C4C6 LOCAL HEADER #34      04034B50 (67324752)
│ │ │ │ +3C4CA Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +3C4CB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +3C4CC General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +3C4CE Compression Method    0008 (8) 'Deflated'
│ │ │ │ +3C4D0 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3C4D4 CRC                   D1448544 (3510928708)
│ │ │ │ +3C4D8 Compressed Size       000009A5 (2469)
│ │ │ │ +3C4DC Uncompressed Size     00001B64 (7012)
│ │ │ │ +3C4E0 Filename Length       0010 (16)
│ │ │ │ +3C4E2 Extra Length          001C (28)
│ │ │ │ +3C4E4 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x3C4E4: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +3C4F4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +3C4F6   Length              0009 (9)
│ │ │ │ +3C4F8   Flags               03 (3) 'Modification Access'
│ │ │ │ +3C4F9   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3C4FD   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3C501 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +3C503   Length              000B (11)
│ │ │ │ +3C505   Version             01 (1)
│ │ │ │ +3C506   UID Size            04 (4)
│ │ │ │ +3C507   UID                 00000000 (0)
│ │ │ │ +3C50B   GID Size            04 (4)
│ │ │ │ +3C50C   GID                 00000000 (0)
│ │ │ │ +3C510 PAYLOAD
│ │ │ │ +
│ │ │ │ +3CEB5 LOCAL HEADER #35      04034B50 (67324752)
│ │ │ │ +3CEB9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +3CEBA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +3CEBB General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +3CEBD Compression Method    0008 (8) 'Deflated'
│ │ │ │ +3CEBF Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3CEC3 CRC                   3E5AEB62 (1046145890)
│ │ │ │ +3CEC7 Compressed Size       000006B7 (1719)
│ │ │ │ +3CECB Uncompressed Size     00001565 (5477)
│ │ │ │ +3CECF Filename Length       0012 (18)
│ │ │ │ +3CED1 Extra Length          001C (28)
│ │ │ │ +3CED3 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x3CED3: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +3CEE5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +3CEE7   Length              0009 (9)
│ │ │ │ +3CEE9   Flags               03 (3) 'Modification Access'
│ │ │ │ +3CEEA   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3CEEE   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3CEF2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +3CEF4   Length              000B (11)
│ │ │ │ +3CEF6   Version             01 (1)
│ │ │ │ +3CEF7   UID Size            04 (4)
│ │ │ │ +3CEF8   UID                 00000000 (0)
│ │ │ │ +3CEFC   GID Size            04 (4)
│ │ │ │ +3CEFD   GID                 00000000 (0)
│ │ │ │ +3CF01 PAYLOAD
│ │ │ │ +
│ │ │ │ +3D5B8 LOCAL HEADER #36      04034B50 (67324752)
│ │ │ │ +3D5BC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +3D5BD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +3D5BE General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +3D5C0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +3D5C2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3D5C6 CRC                   0CAC5654 (212620884)
│ │ │ │ +3D5CA Compressed Size       00002A18 (10776)
│ │ │ │ +3D5CE Uncompressed Size     0000B1C5 (45509)
│ │ │ │ +3D5D2 Filename Length       0010 (16)
│ │ │ │ +3D5D4 Extra Length          001C (28)
│ │ │ │ +3D5D6 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x3D5D6: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +3D5E6 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +3D5E8   Length              0009 (9)
│ │ │ │ +3D5EA   Flags               03 (3) 'Modification Access'
│ │ │ │ +3D5EB   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3D5EF   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +3D5F3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +3D5F5   Length              000B (11)
│ │ │ │ +3D5F7   Version             01 (1)
│ │ │ │ +3D5F8   UID Size            04 (4)
│ │ │ │ +3D5F9   UID                 00000000 (0)
│ │ │ │ +3D5FD   GID Size            04 (4)
│ │ │ │ +3D5FE   GID                 00000000 (0)
│ │ │ │ +3D602 PAYLOAD
│ │ │ │ +
│ │ │ │ +4001A LOCAL HEADER #37      04034B50 (67324752)
│ │ │ │ +4001E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +4001F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +40020 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +40022 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +40024 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +40028 CRC                   7F12A43C (2131928124)
│ │ │ │ +4002C Compressed Size       00001E82 (7810)
│ │ │ │ +40030 Uncompressed Size     00009AAA (39594)
│ │ │ │ +40034 Filename Length       0012 (18)
│ │ │ │ +40036 Extra Length          001C (28)
│ │ │ │ +40038 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x40038: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +4004A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +4004C   Length              0009 (9)
│ │ │ │ +4004E   Flags               03 (3) 'Modification Access'
│ │ │ │ +4004F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +40053   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +40057 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +40059   Length              000B (11)
│ │ │ │ +4005B   Version             01 (1)
│ │ │ │ +4005C   UID Size            04 (4)
│ │ │ │ +4005D   UID                 00000000 (0)
│ │ │ │ +40061   GID Size            04 (4)
│ │ │ │ +40062   GID                 00000000 (0)
│ │ │ │ +40066 PAYLOAD
│ │ │ │ +
│ │ │ │ +41EE8 LOCAL HEADER #38      04034B50 (67324752)
│ │ │ │ +41EEC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +41EED Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +41EEE General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +41EF0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +41EF2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +41EF6 CRC                   E63D084C (3862759500)
│ │ │ │ +41EFA Compressed Size       00001474 (5236)
│ │ │ │ +41EFE Uncompressed Size     00007ACF (31439)
│ │ │ │ +41F02 Filename Length       0018 (24)
│ │ │ │ +41F04 Extra Length          001C (28)
│ │ │ │ +41F06 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x41F06: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +41F1E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +41F20   Length              0009 (9)
│ │ │ │ +41F22   Flags               03 (3) 'Modification Access'
│ │ │ │ +41F23   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +41F27   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +41F2B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +41F2D   Length              000B (11)
│ │ │ │ +41F2F   Version             01 (1)
│ │ │ │ +41F30   UID Size            04 (4)
│ │ │ │ +41F31   UID                 00000000 (0)
│ │ │ │ +41F35   GID Size            04 (4)
│ │ │ │ +41F36   GID                 00000000 (0)
│ │ │ │ +41F3A PAYLOAD
│ │ │ │ +
│ │ │ │ +433AE LOCAL HEADER #39      04034B50 (67324752)
│ │ │ │ +433B2 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +433B3 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +433B4 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +433B6 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +433B8 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +433BC CRC                   2F887888 (797472904)
│ │ │ │ +433C0 Compressed Size       000018CB (6347)
│ │ │ │ +433C4 Uncompressed Size     0000A7F4 (42996)
│ │ │ │ +433C8 Filename Length       001F (31)
│ │ │ │ +433CA Extra Length          001C (28)
│ │ │ │ +433CC Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x433CC: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +433EB Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +433ED   Length              0009 (9)
│ │ │ │ +433EF   Flags               03 (3) 'Modification Access'
│ │ │ │ +433F0   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +433F4   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +433F8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +433FA   Length              000B (11)
│ │ │ │ +433FC   Version             01 (1)
│ │ │ │ +433FD   UID Size            04 (4)
│ │ │ │ +433FE   UID                 00000000 (0)
│ │ │ │ +43402   GID Size            04 (4)
│ │ │ │ +43403   GID                 00000000 (0)
│ │ │ │ +43407 PAYLOAD
│ │ │ │ +
│ │ │ │ +44CD2 LOCAL HEADER #40      04034B50 (67324752)
│ │ │ │ +44CD6 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +44CD7 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +44CD8 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +44CDA Compression Method    0008 (8) 'Deflated'
│ │ │ │ +44CDC Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +44CE0 CRC                   FFAF198F (4289665423)
│ │ │ │ +44CE4 Compressed Size       000003F6 (1014)
│ │ │ │ +44CE8 Uncompressed Size     000008A3 (2211)
│ │ │ │ +44CEC Filename Length       001E (30)
│ │ │ │ +44CEE Extra Length          001C (28)
│ │ │ │ +44CF0 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x44CF0: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +44D0E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +44D10   Length              0009 (9)
│ │ │ │ +44D12   Flags               03 (3) 'Modification Access'
│ │ │ │ +44D13   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +44D17   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +44D1B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +44D1D   Length              000B (11)
│ │ │ │ +44D1F   Version             01 (1)
│ │ │ │ +44D20   UID Size            04 (4)
│ │ │ │ +44D21   UID                 00000000 (0)
│ │ │ │ +44D25   GID Size            04 (4)
│ │ │ │ +44D26   GID                 00000000 (0)
│ │ │ │ +44D2A PAYLOAD
│ │ │ │ +
│ │ │ │ +45120 LOCAL HEADER #41      04034B50 (67324752)
│ │ │ │ +45124 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +45125 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +45126 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +45128 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +4512A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4512E CRC                   32E3FA13 (853801491)
│ │ │ │ +45132 Compressed Size       00004292 (17042)
│ │ │ │ +45136 Uncompressed Size     0000D8DC (55516)
│ │ │ │ +4513A Filename Length       0013 (19)
│ │ │ │ +4513C Extra Length          001C (28)
│ │ │ │ +4513E Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4513E: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +45151 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +45153   Length              0009 (9)
│ │ │ │ +45155   Flags               03 (3) 'Modification Access'
│ │ │ │ +45156   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4515A   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4515E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +45160   Length              000B (11)
│ │ │ │ +45162   Version             01 (1)
│ │ │ │ +45163   UID Size            04 (4)
│ │ │ │ +45164   UID                 00000000 (0)
│ │ │ │ +45168   GID Size            04 (4)
│ │ │ │ +45169   GID                 00000000 (0)
│ │ │ │ +4516D PAYLOAD
│ │ │ │ +
│ │ │ │ +493FF LOCAL HEADER #42      04034B50 (67324752)
│ │ │ │ +49403 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +49404 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +49405 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +49407 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +49409 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4940D CRC                   0AAA7D81 (178945409)
│ │ │ │ +49411 Compressed Size       000026C5 (9925)
│ │ │ │ +49415 Uncompressed Size     00006E45 (28229)
│ │ │ │ +49419 Filename Length       0019 (25)
│ │ │ │ +4941B Extra Length          001C (28)
│ │ │ │ +4941D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4941D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +49436 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +49438   Length              0009 (9)
│ │ │ │ +4943A   Flags               03 (3) 'Modification Access'
│ │ │ │ +4943B   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4943F   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +49443 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +49445   Length              000B (11)
│ │ │ │ +49447   Version             01 (1)
│ │ │ │ +49448   UID Size            04 (4)
│ │ │ │ +49449   UID                 00000000 (0)
│ │ │ │ +4944D   GID Size            04 (4)
│ │ │ │ +4944E   GID                 00000000 (0)
│ │ │ │ +49452 PAYLOAD
│ │ │ │ +
│ │ │ │ +4BB17 LOCAL HEADER #43      04034B50 (67324752)
│ │ │ │ +4BB1B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +4BB1C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +4BB1D General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +4BB1F Compression Method    0008 (8) 'Deflated'
│ │ │ │ +4BB21 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4BB25 CRC                   0369577C (57235324)
│ │ │ │ +4BB29 Compressed Size       00002739 (10041)
│ │ │ │ +4BB2D Uncompressed Size     00008B83 (35715)
│ │ │ │ +4BB31 Filename Length       0019 (25)
│ │ │ │ +4BB33 Extra Length          001C (28)
│ │ │ │ +4BB35 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4BB35: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +4BB4E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +4BB50   Length              0009 (9)
│ │ │ │ +4BB52   Flags               03 (3) 'Modification Access'
│ │ │ │ +4BB53   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4BB57   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4BB5B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +4BB5D   Length              000B (11)
│ │ │ │ +4BB5F   Version             01 (1)
│ │ │ │ +4BB60   UID Size            04 (4)
│ │ │ │ +4BB61   UID                 00000000 (0)
│ │ │ │ +4BB65   GID Size            04 (4)
│ │ │ │ +4BB66   GID                 00000000 (0)
│ │ │ │ +4BB6A PAYLOAD
│ │ │ │ +
│ │ │ │ +4E2A3 LOCAL HEADER #44      04034B50 (67324752)
│ │ │ │ +4E2A7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +4E2A8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +4E2A9 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +4E2AB Compression Method    0008 (8) 'Deflated'
│ │ │ │ +4E2AD Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4E2B1 CRC                   6DB8C629 (1840825897)
│ │ │ │ +4E2B5 Compressed Size       00000CF2 (3314)
│ │ │ │ +4E2B9 Uncompressed Size     0000517A (20858)
│ │ │ │ +4E2BD Filename Length       0021 (33)
│ │ │ │ +4E2BF Extra Length          001C (28)
│ │ │ │ +4E2C1 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4E2C1: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +4E2E2 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +4E2E4   Length              0009 (9)
│ │ │ │ +4E2E6   Flags               03 (3) 'Modification Access'
│ │ │ │ +4E2E7   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4E2EB   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4E2EF Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +4E2F1   Length              000B (11)
│ │ │ │ +4E2F3   Version             01 (1)
│ │ │ │ +4E2F4   UID Size            04 (4)
│ │ │ │ +4E2F5   UID                 00000000 (0)
│ │ │ │ +4E2F9   GID Size            04 (4)
│ │ │ │ +4E2FA   GID                 00000000 (0)
│ │ │ │ +4E2FE PAYLOAD
│ │ │ │ +
│ │ │ │ +4EFF0 LOCAL HEADER #45      04034B50 (67324752)
│ │ │ │ +4EFF4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +4EFF5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +4EFF6 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +4EFF8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +4EFFA Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4EFFE CRC                   8F01E69C (2399266460)
│ │ │ │ +4F002 Compressed Size       00000468 (1128)
│ │ │ │ +4F006 Uncompressed Size     00000931 (2353)
│ │ │ │ +4F00A Filename Length       001B (27)
│ │ │ │ +4F00C Extra Length          001C (28)
│ │ │ │ +4F00E Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4F00E: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +4F029 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +4F02B   Length              0009 (9)
│ │ │ │ +4F02D   Flags               03 (3) 'Modification Access'
│ │ │ │ +4F02E   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4F032   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4F036 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +4F038   Length              000B (11)
│ │ │ │ +4F03A   Version             01 (1)
│ │ │ │ +4F03B   UID Size            04 (4)
│ │ │ │ +4F03C   UID                 00000000 (0)
│ │ │ │ +4F040   GID Size            04 (4)
│ │ │ │ +4F041   GID                 00000000 (0)
│ │ │ │ +4F045 PAYLOAD
│ │ │ │ +
│ │ │ │ +4F4AD LOCAL HEADER #46      04034B50 (67324752)
│ │ │ │ +4F4B1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +4F4B2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +4F4B3 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +4F4B5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +4F4B7 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4F4BB CRC                   0D0600BA (218497210)
│ │ │ │ +4F4BF Compressed Size       000016EF (5871)
│ │ │ │ +4F4C3 Uncompressed Size     00007A6D (31341)
│ │ │ │ +4F4C7 Filename Length       001F (31)
│ │ │ │ +4F4C9 Extra Length          001C (28)
│ │ │ │ +4F4CB Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x4F4CB: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +4F4EA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +4F4EC   Length              0009 (9)
│ │ │ │ +4F4EE   Flags               03 (3) 'Modification Access'
│ │ │ │ +4F4EF   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4F4F3   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +4F4F7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +4F4F9   Length              000B (11)
│ │ │ │ +4F4FB   Version             01 (1)
│ │ │ │ +4F4FC   UID Size            04 (4)
│ │ │ │ +4F4FD   UID                 00000000 (0)
│ │ │ │ +4F501   GID Size            04 (4)
│ │ │ │ +4F502   GID                 00000000 (0)
│ │ │ │ +4F506 PAYLOAD
│ │ │ │ +
│ │ │ │ +50BF5 LOCAL HEADER #47      04034B50 (67324752)
│ │ │ │ +50BF9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +50BFA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +50BFB General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +50BFD Compression Method    0008 (8) 'Deflated'
│ │ │ │ +50BFF Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +50C03 CRC                   F6942733 (4136904499)
│ │ │ │ +50C07 Compressed Size       00004177 (16759)
│ │ │ │ +50C0B Uncompressed Size     0001CF93 (118675)
│ │ │ │ +50C0F Filename Length       0010 (16)
│ │ │ │ +50C11 Extra Length          001C (28)
│ │ │ │ +50C13 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x50C13: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +50C23 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +50C25   Length              0009 (9)
│ │ │ │ +50C27   Flags               03 (3) 'Modification Access'
│ │ │ │ +50C28   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +50C2C   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +50C30 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +50C32   Length              000B (11)
│ │ │ │ +50C34   Version             01 (1)
│ │ │ │ +50C35   UID Size            04 (4)
│ │ │ │ +50C36   UID                 00000000 (0)
│ │ │ │ +50C3A   GID Size            04 (4)
│ │ │ │ +50C3B   GID                 00000000 (0)
│ │ │ │ +50C3F PAYLOAD
│ │ │ │ +
│ │ │ │ +54DB6 LOCAL HEADER #48      04034B50 (67324752)
│ │ │ │ +54DBA Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +54DBB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +54DBC General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +54DBE Compression Method    0008 (8) 'Deflated'
│ │ │ │ +54DC0 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +54DC4 CRC                   2020DAF6 (539024118)
│ │ │ │ +54DC8 Compressed Size       00000A94 (2708)
│ │ │ │ +54DCC Uncompressed Size     00002105 (8453)
│ │ │ │ +54DD0 Filename Length       0014 (20)
│ │ │ │ +54DD2 Extra Length          001C (28)
│ │ │ │ +54DD4 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x54DD4: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +54DE8 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +54DEA   Length              0009 (9)
│ │ │ │ +54DEC   Flags               03 (3) 'Modification Access'
│ │ │ │ +54DED   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +54DF1   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +54DF5 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +54DF7   Length              000B (11)
│ │ │ │ +54DF9   Version             01 (1)
│ │ │ │ +54DFA   UID Size            04 (4)
│ │ │ │ +54DFB   UID                 00000000 (0)
│ │ │ │ +54DFF   GID Size            04 (4)
│ │ │ │ +54E00   GID                 00000000 (0)
│ │ │ │ +54E04 PAYLOAD
│ │ │ │ +
│ │ │ │ +55898 LOCAL HEADER #49      04034B50 (67324752)
│ │ │ │ +5589C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +5589D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +5589E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +558A0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +558A2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +558A6 CRC                   B73364B1 (3073598641)
│ │ │ │ +558AA Compressed Size       0000ACA6 (44198)
│ │ │ │ +558AE Uncompressed Size     0003E418 (255000)
│ │ │ │ +558B2 Filename Length       0017 (23)
│ │ │ │ +558B4 Extra Length          001C (28)
│ │ │ │ +558B6 Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x558B6: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +558CD Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +558CF   Length              0009 (9)
│ │ │ │ +558D1   Flags               03 (3) 'Modification Access'
│ │ │ │ +558D2   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +558D6   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +558DA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +558DC   Length              000B (11)
│ │ │ │ +558DE   Version             01 (1)
│ │ │ │ +558DF   UID Size            04 (4)
│ │ │ │ +558E0   UID                 00000000 (0)
│ │ │ │ +558E4   GID Size            04 (4)
│ │ │ │ +558E5   GID                 00000000 (0)
│ │ │ │ +558E9 PAYLOAD
│ │ │ │ +
│ │ │ │ +6058F LOCAL HEADER #50      04034B50 (67324752)
│ │ │ │ +60593 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +60594 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +60595 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +60597 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +60599 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6059D CRC                   102FB47C (271561852)
│ │ │ │ +605A1 Compressed Size       00000401 (1025)
│ │ │ │ +605A5 Uncompressed Size     0000093D (2365)
│ │ │ │ +605A9 Filename Length       0013 (19)
│ │ │ │ +605AB Extra Length          001C (28)
│ │ │ │ +605AD Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x605AD: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +605C0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +605C2   Length              0009 (9)
│ │ │ │ +605C4   Flags               03 (3) 'Modification Access'
│ │ │ │ +605C5   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +605C9   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +605CD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +605CF   Length              000B (11)
│ │ │ │ +605D1   Version             01 (1)
│ │ │ │ +605D2   UID Size            04 (4)
│ │ │ │ +605D3   UID                 00000000 (0)
│ │ │ │ +605D7   GID Size            04 (4)
│ │ │ │ +605D8   GID                 00000000 (0)
│ │ │ │ +605DC PAYLOAD
│ │ │ │ +
│ │ │ │ +609DD LOCAL HEADER #51      04034B50 (67324752)
│ │ │ │ +609E1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +609E2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +609E3 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +609E5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +609E7 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +609EB CRC                   B3F70F09 (3019312905)
│ │ │ │ +609EF Compressed Size       000014E4 (5348)
│ │ │ │ +609F3 Uncompressed Size     0000687B (26747)
│ │ │ │ +609F7 Filename Length       0012 (18)
│ │ │ │ +609F9 Extra Length          001C (28)
│ │ │ │ +609FB Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x609FB: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +60A0D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +60A0F   Length              0009 (9)
│ │ │ │ +60A11   Flags               03 (3) 'Modification Access'
│ │ │ │ +60A12   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +60A16   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +60A1A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +60A1C   Length              000B (11)
│ │ │ │ +60A1E   Version             01 (1)
│ │ │ │ +60A1F   UID Size            04 (4)
│ │ │ │ +60A20   UID                 00000000 (0)
│ │ │ │ +60A24   GID Size            04 (4)
│ │ │ │ +60A25   GID                 00000000 (0)
│ │ │ │ +60A29 PAYLOAD
│ │ │ │ +
│ │ │ │ +61F0D LOCAL HEADER #52      04034B50 (67324752)
│ │ │ │ +61F11 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +61F12 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +61F13 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +61F15 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +61F17 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +61F1B CRC                   44472F97 (1145515927)
│ │ │ │ +61F1F Compressed Size       000011EB (4587)
│ │ │ │ +61F23 Uncompressed Size     000040F5 (16629)
│ │ │ │ +61F27 Filename Length       0012 (18)
│ │ │ │ +61F29 Extra Length          001C (28)
│ │ │ │ +61F2B Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x61F2B: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +61F3D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +61F3F   Length              0009 (9)
│ │ │ │ +61F41   Flags               03 (3) 'Modification Access'
│ │ │ │ +61F42   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +61F46   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +61F4A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +61F4C   Length              000B (11)
│ │ │ │ +61F4E   Version             01 (1)
│ │ │ │ +61F4F   UID Size            04 (4)
│ │ │ │ +61F50   UID                 00000000 (0)
│ │ │ │ +61F54   GID Size            04 (4)
│ │ │ │ +61F55   GID                 00000000 (0)
│ │ │ │ +61F59 PAYLOAD
│ │ │ │ +
│ │ │ │ +63144 LOCAL HEADER #53      04034B50 (67324752)
│ │ │ │ +63148 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +63149 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +6314A General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +6314C Compression Method    0008 (8) 'Deflated'
│ │ │ │ +6314E Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +63152 CRC                   5D525827 (1565677607)
│ │ │ │ +63156 Compressed Size       000009DA (2522)
│ │ │ │ +6315A Uncompressed Size     00003529 (13609)
│ │ │ │ +6315E Filename Length       0019 (25)
│ │ │ │ +63160 Extra Length          001C (28)
│ │ │ │ +63162 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x63162: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +6317B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +6317D   Length              0009 (9)
│ │ │ │ +6317F   Flags               03 (3) 'Modification Access'
│ │ │ │ +63180   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +63184   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +63188 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +6318A   Length              000B (11)
│ │ │ │ +6318C   Version             01 (1)
│ │ │ │ +6318D   UID Size            04 (4)
│ │ │ │ +6318E   UID                 00000000 (0)
│ │ │ │ +63192   GID Size            04 (4)
│ │ │ │ +63193   GID                 00000000 (0)
│ │ │ │ +63197 PAYLOAD
│ │ │ │ +
│ │ │ │ +63B71 LOCAL HEADER #54      04034B50 (67324752)
│ │ │ │ +63B75 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +63B76 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +63B77 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +63B79 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +63B7B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +63B7F CRC                   9170A9FB (2440079867)
│ │ │ │ +63B83 Compressed Size       000018B3 (6323)
│ │ │ │ +63B87 Uncompressed Size     0000A605 (42501)
│ │ │ │ +63B8B Filename Length       0019 (25)
│ │ │ │ +63B8D Extra Length          001C (28)
│ │ │ │ +63B8F Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x63B8F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +63BA8 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +63BAA   Length              0009 (9)
│ │ │ │ +63BAC   Flags               03 (3) 'Modification Access'
│ │ │ │ +63BAD   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +63BB1   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +63BB5 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +63BB7   Length              000B (11)
│ │ │ │ +63BB9   Version             01 (1)
│ │ │ │ +63BBA   UID Size            04 (4)
│ │ │ │ +63BBB   UID                 00000000 (0)
│ │ │ │ +63BBF   GID Size            04 (4)
│ │ │ │ +63BC0   GID                 00000000 (0)
│ │ │ │ +63BC4 PAYLOAD
│ │ │ │ +
│ │ │ │ +65477 LOCAL HEADER #55      04034B50 (67324752)
│ │ │ │ +6547B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +6547C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +6547D General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +6547F Compression Method    0008 (8) 'Deflated'
│ │ │ │ +65481 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +65485 CRC                   47E0D6DC (1205917404)
│ │ │ │ +65489 Compressed Size       0000177E (6014)
│ │ │ │ +6548D Uncompressed Size     0000472C (18220)
│ │ │ │ +65491 Filename Length       0014 (20)
│ │ │ │ +65493 Extra Length          001C (28)
│ │ │ │ +65495 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x65495: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +654A9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +654AB   Length              0009 (9)
│ │ │ │ +654AD   Flags               03 (3) 'Modification Access'
│ │ │ │ +654AE   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +654B2   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +654B6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +654B8   Length              000B (11)
│ │ │ │ +654BA   Version             01 (1)
│ │ │ │ +654BB   UID Size            04 (4)
│ │ │ │ +654BC   UID                 00000000 (0)
│ │ │ │ +654C0   GID Size            04 (4)
│ │ │ │ +654C1   GID                 00000000 (0)
│ │ │ │ +654C5 PAYLOAD
│ │ │ │ +
│ │ │ │ +66C43 LOCAL HEADER #56      04034B50 (67324752)
│ │ │ │ +66C47 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +66C48 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +66C49 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +66C4B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +66C4D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +66C51 CRC                   EDF51269 (3992261225)
│ │ │ │ +66C55 Compressed Size       0000040B (1035)
│ │ │ │ +66C59 Uncompressed Size     00000825 (2085)
│ │ │ │ +66C5D Filename Length       001C (28)
│ │ │ │ +66C5F Extra Length          001C (28)
│ │ │ │ +66C61 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x66C61: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +66C7D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +66C7F   Length              0009 (9)
│ │ │ │ +66C81   Flags               03 (3) 'Modification Access'
│ │ │ │ +66C82   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +66C86   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +66C8A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +66C8C   Length              000B (11)
│ │ │ │ +66C8E   Version             01 (1)
│ │ │ │ +66C8F   UID Size            04 (4)
│ │ │ │ +66C90   UID                 00000000 (0)
│ │ │ │ +66C94   GID Size            04 (4)
│ │ │ │ +66C95   GID                 00000000 (0)
│ │ │ │ +66C99 PAYLOAD
│ │ │ │ +
│ │ │ │ +670A4 LOCAL HEADER #57      04034B50 (67324752)
│ │ │ │ +670A8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +670A9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +670AA General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +670AC Compression Method    0008 (8) 'Deflated'
│ │ │ │ +670AE Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +670B2 CRC                   3F7C9239 (1065128505)
│ │ │ │ +670B6 Compressed Size       00002480 (9344)
│ │ │ │ +670BA Uncompressed Size     0000B56F (46447)
│ │ │ │ +670BE Filename Length       001F (31)
│ │ │ │ +670C0 Extra Length          001C (28)
│ │ │ │ +670C2 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x670C2: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +670E1 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +670E3   Length              0009 (9)
│ │ │ │ +670E5   Flags               03 (3) 'Modification Access'
│ │ │ │ +670E6   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +670EA   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +670EE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +670F0   Length              000B (11)
│ │ │ │ +670F2   Version             01 (1)
│ │ │ │ +670F3   UID Size            04 (4)
│ │ │ │ +670F4   UID                 00000000 (0)
│ │ │ │ +670F8   GID Size            04 (4)
│ │ │ │ +670F9   GID                 00000000 (0)
│ │ │ │ +670FD PAYLOAD
│ │ │ │ +
│ │ │ │ +6957D LOCAL HEADER #58      04034B50 (67324752)
│ │ │ │ +69581 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +69582 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +69583 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +69585 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +69587 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6958B CRC                   870D678F (2265802639)
│ │ │ │ +6958F Compressed Size       00000E7D (3709)
│ │ │ │ +69593 Uncompressed Size     000052D9 (21209)
│ │ │ │ +69597 Filename Length       001F (31)
│ │ │ │ +69599 Extra Length          001C (28)
│ │ │ │ +6959B Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x6959B: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +695BA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +695BC   Length              0009 (9)
│ │ │ │ +695BE   Flags               03 (3) 'Modification Access'
│ │ │ │ +695BF   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +695C3   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +695C7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +695C9   Length              000B (11)
│ │ │ │ +695CB   Version             01 (1)
│ │ │ │ +695CC   UID Size            04 (4)
│ │ │ │ +695CD   UID                 00000000 (0)
│ │ │ │ +695D1   GID Size            04 (4)
│ │ │ │ +695D2   GID                 00000000 (0)
│ │ │ │ +695D6 PAYLOAD
│ │ │ │ +
│ │ │ │ +6A453 LOCAL HEADER #59      04034B50 (67324752)
│ │ │ │ +6A457 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +6A458 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +6A459 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +6A45B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +6A45D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6A461 CRC                   862D2937 (2251106615)
│ │ │ │ +6A465 Compressed Size       00000A44 (2628)
│ │ │ │ +6A469 Uncompressed Size     0000247A (9338)
│ │ │ │ +6A46D Filename Length       0013 (19)
│ │ │ │ +6A46F Extra Length          001C (28)
│ │ │ │ +6A471 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x6A471: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +6A484 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +6A486   Length              0009 (9)
│ │ │ │ +6A488   Flags               03 (3) 'Modification Access'
│ │ │ │ +6A489   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6A48D   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6A491 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +6A493   Length              000B (11)
│ │ │ │ +6A495   Version             01 (1)
│ │ │ │ +6A496   UID Size            04 (4)
│ │ │ │ +6A497   UID                 00000000 (0)
│ │ │ │ +6A49B   GID Size            04 (4)
│ │ │ │ +6A49C   GID                 00000000 (0)
│ │ │ │ +6A4A0 PAYLOAD
│ │ │ │ +
│ │ │ │ +6AEE4 LOCAL HEADER #60      04034B50 (67324752)
│ │ │ │ +6AEE8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +6AEE9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +6AEEA General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +6AEEC Compression Method    0008 (8) 'Deflated'
│ │ │ │ +6AEEE Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6AEF2 CRC                   EB0E516C (3943584108)
│ │ │ │ +6AEF6 Compressed Size       00002489 (9353)
│ │ │ │ +6AEFA Uncompressed Size     0000B84C (47180)
│ │ │ │ +6AEFE Filename Length       0019 (25)
│ │ │ │ +6AF00 Extra Length          001C (28)
│ │ │ │ +6AF02 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x6AF02: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +6AF1B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +6AF1D   Length              0009 (9)
│ │ │ │ +6AF1F   Flags               03 (3) 'Modification Access'
│ │ │ │ +6AF20   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6AF24   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6AF28 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +6AF2A   Length              000B (11)
│ │ │ │ +6AF2C   Version             01 (1)
│ │ │ │ +6AF2D   UID Size            04 (4)
│ │ │ │ +6AF2E   UID                 00000000 (0)
│ │ │ │ +6AF32   GID Size            04 (4)
│ │ │ │ +6AF33   GID                 00000000 (0)
│ │ │ │ +6AF37 PAYLOAD
│ │ │ │ +
│ │ │ │ +6D3C0 LOCAL HEADER #61      04034B50 (67324752)
│ │ │ │ +6D3C4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +6D3C5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +6D3C6 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +6D3C8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +6D3CA Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6D3CE CRC                   5D7EB216 (1568584214)
│ │ │ │ +6D3D2 Compressed Size       00000EFA (3834)
│ │ │ │ +6D3D6 Uncompressed Size     00003A2C (14892)
│ │ │ │ +6D3DA Filename Length       0024 (36)
│ │ │ │ +6D3DC Extra Length          001C (28)
│ │ │ │ +6D3DE Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x6D3DE: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +6D402 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +6D404   Length              0009 (9)
│ │ │ │ +6D406   Flags               03 (3) 'Modification Access'
│ │ │ │ +6D407   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6D40B   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6D40F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +6D411   Length              000B (11)
│ │ │ │ +6D413   Version             01 (1)
│ │ │ │ +6D414   UID Size            04 (4)
│ │ │ │ +6D415   UID                 00000000 (0)
│ │ │ │ +6D419   GID Size            04 (4)
│ │ │ │ +6D41A   GID                 00000000 (0)
│ │ │ │ +6D41E PAYLOAD
│ │ │ │ +
│ │ │ │ +6E318 LOCAL HEADER #62      04034B50 (67324752)
│ │ │ │ +6E31C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +6E31D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +6E31E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +6E320 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +6E322 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6E326 CRC                   AC96636E (2895537006)
│ │ │ │ +6E32A Compressed Size       00001AC0 (6848)
│ │ │ │ +6E32E Uncompressed Size     00005EDC (24284)
│ │ │ │ +6E332 Filename Length       0017 (23)
│ │ │ │ +6E334 Extra Length          001C (28)
│ │ │ │ +6E336 Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x6E336: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +6E34D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +6E34F   Length              0009 (9)
│ │ │ │ +6E351   Flags               03 (3) 'Modification Access'
│ │ │ │ +6E352   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6E356   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6E35A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +6E35C   Length              000B (11)
│ │ │ │ +6E35E   Version             01 (1)
│ │ │ │ +6E35F   UID Size            04 (4)
│ │ │ │ +6E360   UID                 00000000 (0)
│ │ │ │ +6E364   GID Size            04 (4)
│ │ │ │ +6E365   GID                 00000000 (0)
│ │ │ │ +6E369 PAYLOAD
│ │ │ │ +
│ │ │ │ +6FE29 LOCAL HEADER #63      04034B50 (67324752)
│ │ │ │ +6FE2D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +6FE2E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +6FE2F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +6FE31 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +6FE33 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6FE37 CRC                   11E32AF1 (300100337)
│ │ │ │ +6FE3B Compressed Size       00000ED3 (3795)
│ │ │ │ +6FE3F Uncompressed Size     000038E2 (14562)
│ │ │ │ +6FE43 Filename Length       0023 (35)
│ │ │ │ +6FE45 Extra Length          001C (28)
│ │ │ │ +6FE47 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x6FE47: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +6FE6A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +6FE6C   Length              0009 (9)
│ │ │ │ +6FE6E   Flags               03 (3) 'Modification Access'
│ │ │ │ +6FE6F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6FE73   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +6FE77 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +6FE79   Length              000B (11)
│ │ │ │ +6FE7B   Version             01 (1)
│ │ │ │ +6FE7C   UID Size            04 (4)
│ │ │ │ +6FE7D   UID                 00000000 (0)
│ │ │ │ +6FE81   GID Size            04 (4)
│ │ │ │ +6FE82   GID                 00000000 (0)
│ │ │ │ +6FE86 PAYLOAD
│ │ │ │ +
│ │ │ │ +70D59 LOCAL HEADER #64      04034B50 (67324752)
│ │ │ │ +70D5D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +70D5E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +70D5F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +70D61 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +70D63 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +70D67 CRC                   2DB7929F (767005343)
│ │ │ │ +70D6B Compressed Size       00000113 (275)
│ │ │ │ +70D6F Uncompressed Size     000001F3 (499)
│ │ │ │ +70D73 Filename Length       001B (27)
│ │ │ │ +70D75 Extra Length          001C (28)
│ │ │ │ +70D77 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x70D77: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +70D92 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +70D94   Length              0009 (9)
│ │ │ │ +70D96   Flags               03 (3) 'Modification Access'
│ │ │ │ +70D97   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +70D9B   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +70D9F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +70DA1   Length              000B (11)
│ │ │ │ +70DA3   Version             01 (1)
│ │ │ │ +70DA4   UID Size            04 (4)
│ │ │ │ +70DA5   UID                 00000000 (0)
│ │ │ │ +70DA9   GID Size            04 (4)
│ │ │ │ +70DAA   GID                 00000000 (0)
│ │ │ │ +70DAE PAYLOAD
│ │ │ │ +
│ │ │ │ +70EC1 LOCAL HEADER #65      04034B50 (67324752)
│ │ │ │ +70EC5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +70EC6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +70EC7 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +70EC9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +70ECB Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +70ECF CRC                   BF2C5594 (3207353748)
│ │ │ │ +70ED3 Compressed Size       00001890 (6288)
│ │ │ │ +70ED7 Uncompressed Size     00008FAC (36780)
│ │ │ │ +70EDB Filename Length       001D (29)
│ │ │ │ +70EDD Extra Length          001C (28)
│ │ │ │ +70EDF Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x70EDF: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +70EFC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +70EFE   Length              0009 (9)
│ │ │ │ +70F00   Flags               03 (3) 'Modification Access'
│ │ │ │ +70F01   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +70F05   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +70F09 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +70F0B   Length              000B (11)
│ │ │ │ +70F0D   Version             01 (1)
│ │ │ │ +70F0E   UID Size            04 (4)
│ │ │ │ +70F0F   UID                 00000000 (0)
│ │ │ │ +70F13   GID Size            04 (4)
│ │ │ │ +70F14   GID                 00000000 (0)
│ │ │ │ +70F18 PAYLOAD
│ │ │ │ +
│ │ │ │ +727A8 LOCAL HEADER #66      04034B50 (67324752)
│ │ │ │ +727AC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +727AD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +727AE General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +727B0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +727B2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +727B6 CRC                   63FED801 (1677645825)
│ │ │ │ +727BA Compressed Size       0000164D (5709)
│ │ │ │ +727BE Uncompressed Size     00003A9B (15003)
│ │ │ │ +727C2 Filename Length       0015 (21)
│ │ │ │ +727C4 Extra Length          001C (28)
│ │ │ │ +727C6 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x727C6: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +727DB Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +727DD   Length              0009 (9)
│ │ │ │ +727DF   Flags               03 (3) 'Modification Access'
│ │ │ │ +727E0   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +727E4   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +727E8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +727EA   Length              000B (11)
│ │ │ │ +727EC   Version             01 (1)
│ │ │ │ +727ED   UID Size            04 (4)
│ │ │ │ +727EE   UID                 00000000 (0)
│ │ │ │ +727F2   GID Size            04 (4)
│ │ │ │ +727F3   GID                 00000000 (0)
│ │ │ │ +727F7 PAYLOAD
│ │ │ │ +
│ │ │ │ +73E44 LOCAL HEADER #67      04034B50 (67324752)
│ │ │ │ +73E48 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +73E49 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +73E4A General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +73E4C Compression Method    0008 (8) 'Deflated'
│ │ │ │ +73E4E Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +73E52 CRC                   C4C757ED (3301398509)
│ │ │ │ +73E56 Compressed Size       00003B50 (15184)
│ │ │ │ +73E5A Uncompressed Size     0001185B (71771)
│ │ │ │ +73E5E Filename Length       0016 (22)
│ │ │ │ +73E60 Extra Length          001C (28)
│ │ │ │ +73E62 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x73E62: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +73E78 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +73E7A   Length              0009 (9)
│ │ │ │ +73E7C   Flags               03 (3) 'Modification Access'
│ │ │ │ +73E7D   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +73E81   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +73E85 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +73E87   Length              000B (11)
│ │ │ │ +73E89   Version             01 (1)
│ │ │ │ +73E8A   UID Size            04 (4)
│ │ │ │ +73E8B   UID                 00000000 (0)
│ │ │ │ +73E8F   GID Size            04 (4)
│ │ │ │ +73E90   GID                 00000000 (0)
│ │ │ │ +73E94 PAYLOAD
│ │ │ │ +
│ │ │ │ +779E4 LOCAL HEADER #68      04034B50 (67324752)
│ │ │ │ +779E8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +779E9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +779EA General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +779EC Compression Method    0008 (8) 'Deflated'
│ │ │ │ +779EE Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +779F2 CRC                   4A54A065 (1247060069)
│ │ │ │ +779F6 Compressed Size       00003E86 (16006)
│ │ │ │ +779FA Uncompressed Size     0001C17B (115067)
│ │ │ │ +779FE Filename Length       0019 (25)
│ │ │ │ +77A00 Extra Length          001C (28)
│ │ │ │ +77A02 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x77A02: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +77A1B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +77A1D   Length              0009 (9)
│ │ │ │ +77A1F   Flags               03 (3) 'Modification Access'
│ │ │ │ +77A20   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +77A24   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +77A28 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +77A2A   Length              000B (11)
│ │ │ │ +77A2C   Version             01 (1)
│ │ │ │ +77A2D   UID Size            04 (4)
│ │ │ │ +77A2E   UID                 00000000 (0)
│ │ │ │ +77A32   GID Size            04 (4)
│ │ │ │ +77A33   GID                 00000000 (0)
│ │ │ │ +77A37 PAYLOAD
│ │ │ │ +
│ │ │ │ +7B8BD LOCAL HEADER #69      04034B50 (67324752)
│ │ │ │ +7B8C1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +7B8C2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +7B8C3 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +7B8C5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +7B8C7 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +7B8CB CRC                   04806937 (75524407)
│ │ │ │ +7B8CF Compressed Size       00000838 (2104)
│ │ │ │ +7B8D3 Uncompressed Size     00003383 (13187)
│ │ │ │ +7B8D7 Filename Length       0011 (17)
│ │ │ │ +7B8D9 Extra Length          001C (28)
│ │ │ │ +7B8DB Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x7B8DB: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +7B8EC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +7B8EE   Length              0009 (9)
│ │ │ │ +7B8F0   Flags               03 (3) 'Modification Access'
│ │ │ │ +7B8F1   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +7B8F5   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +7B8F9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +7B8FB   Length              000B (11)
│ │ │ │ +7B8FD   Version             01 (1)
│ │ │ │ +7B8FE   UID Size            04 (4)
│ │ │ │ +7B8FF   UID                 00000000 (0)
│ │ │ │ +7B903   GID Size            04 (4)
│ │ │ │ +7B904   GID                 00000000 (0)
│ │ │ │ +7B908 PAYLOAD
│ │ │ │ +
│ │ │ │ +7C140 LOCAL HEADER #70      04034B50 (67324752)
│ │ │ │ +7C144 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +7C145 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +7C146 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +7C148 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +7C14A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +7C14E CRC                   02DF6A89 (48196233)
│ │ │ │ +7C152 Compressed Size       00005188 (20872)
│ │ │ │ +7C156 Uncompressed Size     0001FB6C (129900)
│ │ │ │ +7C15A Filename Length       0015 (21)
│ │ │ │ +7C15C Extra Length          001C (28)
│ │ │ │ +7C15E Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x7C15E: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +7C173 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +7C175   Length              0009 (9)
│ │ │ │ +7C177   Flags               03 (3) 'Modification Access'
│ │ │ │ +7C178   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +7C17C   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +7C180 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +7C182   Length              000B (11)
│ │ │ │ +7C184   Version             01 (1)
│ │ │ │ +7C185   UID Size            04 (4)
│ │ │ │ +7C186   UID                 00000000 (0)
│ │ │ │ +7C18A   GID Size            04 (4)
│ │ │ │ +7C18B   GID                 00000000 (0)
│ │ │ │ +7C18F PAYLOAD
│ │ │ │ +
│ │ │ │ +81317 LOCAL HEADER #71      04034B50 (67324752)
│ │ │ │ +8131B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +8131C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +8131D General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +8131F Compression Method    0008 (8) 'Deflated'
│ │ │ │ +81321 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +81325 CRC                   9F6D82FD (2674754301)
│ │ │ │ +81329 Compressed Size       00001B09 (6921)
│ │ │ │ +8132D Uncompressed Size     000081CF (33231)
│ │ │ │ +81331 Filename Length       0019 (25)
│ │ │ │ +81333 Extra Length          001C (28)
│ │ │ │ +81335 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x81335: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +8134E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +81350   Length              0009 (9)
│ │ │ │ +81352   Flags               03 (3) 'Modification Access'
│ │ │ │ +81353   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +81357   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8135B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +8135D   Length              000B (11)
│ │ │ │ +8135F   Version             01 (1)
│ │ │ │ +81360   UID Size            04 (4)
│ │ │ │ +81361   UID                 00000000 (0)
│ │ │ │ +81365   GID Size            04 (4)
│ │ │ │ +81366   GID                 00000000 (0)
│ │ │ │ +8136A PAYLOAD
│ │ │ │ +
│ │ │ │ +82E73 LOCAL HEADER #72      04034B50 (67324752)
│ │ │ │ +82E77 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +82E78 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +82E79 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +82E7B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +82E7D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +82E81 CRC                   112D8470 (288195696)
│ │ │ │ +82E85 Compressed Size       00000D97 (3479)
│ │ │ │ +82E89 Uncompressed Size     00002E9F (11935)
│ │ │ │ +82E8D Filename Length       0018 (24)
│ │ │ │ +82E8F Extra Length          001C (28)
│ │ │ │ +82E91 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x82E91: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +82EA9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +82EAB   Length              0009 (9)
│ │ │ │ +82EAD   Flags               03 (3) 'Modification Access'
│ │ │ │ +82EAE   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +82EB2   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +82EB6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +82EB8   Length              000B (11)
│ │ │ │ +82EBA   Version             01 (1)
│ │ │ │ +82EBB   UID Size            04 (4)
│ │ │ │ +82EBC   UID                 00000000 (0)
│ │ │ │ +82EC0   GID Size            04 (4)
│ │ │ │ +82EC1   GID                 00000000 (0)
│ │ │ │ +82EC5 PAYLOAD
│ │ │ │ +
│ │ │ │ +83C5C LOCAL HEADER #73      04034B50 (67324752)
│ │ │ │ +83C60 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +83C61 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +83C62 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +83C64 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +83C66 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +83C6A CRC                   B429472D (3022604077)
│ │ │ │ +83C6E Compressed Size       000001E1 (481)
│ │ │ │ +83C72 Uncompressed Size     00000323 (803)
│ │ │ │ +83C76 Filename Length       0011 (17)
│ │ │ │ +83C78 Extra Length          001C (28)
│ │ │ │ +83C7A Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x83C7A: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +83C8B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +83C8D   Length              0009 (9)
│ │ │ │ +83C8F   Flags               03 (3) 'Modification Access'
│ │ │ │ +83C90   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +83C94   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +83C98 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +83C9A   Length              000B (11)
│ │ │ │ +83C9C   Version             01 (1)
│ │ │ │ +83C9D   UID Size            04 (4)
│ │ │ │ +83C9E   UID                 00000000 (0)
│ │ │ │ +83CA2   GID Size            04 (4)
│ │ │ │ +83CA3   GID                 00000000 (0)
│ │ │ │ +83CA7 PAYLOAD
│ │ │ │ +
│ │ │ │ +83E88 LOCAL HEADER #74      04034B50 (67324752)
│ │ │ │ +83E8C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +83E8D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +83E8E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +83E90 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +83E92 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +83E96 CRC                   1E45F0E3 (507900131)
│ │ │ │ +83E9A Compressed Size       000006C1 (1729)
│ │ │ │ +83E9E Uncompressed Size     00001439 (5177)
│ │ │ │ +83EA2 Filename Length       0019 (25)
│ │ │ │ +83EA4 Extra Length          001C (28)
│ │ │ │ +83EA6 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x83EA6: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +83EBF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +83EC1   Length              0009 (9)
│ │ │ │ +83EC3   Flags               03 (3) 'Modification Access'
│ │ │ │ +83EC4   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +83EC8   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +83ECC Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +83ECE   Length              000B (11)
│ │ │ │ +83ED0   Version             01 (1)
│ │ │ │ +83ED1   UID Size            04 (4)
│ │ │ │ +83ED2   UID                 00000000 (0)
│ │ │ │ +83ED6   GID Size            04 (4)
│ │ │ │ +83ED7   GID                 00000000 (0)
│ │ │ │ +83EDB PAYLOAD
│ │ │ │ +
│ │ │ │ +8459C LOCAL HEADER #75      04034B50 (67324752)
│ │ │ │ +845A0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +845A1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +845A2 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +845A4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +845A6 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +845AA CRC                   2E699024 (778670116)
│ │ │ │ +845AE Compressed Size       00001B8B (7051)
│ │ │ │ +845B2 Uncompressed Size     00009F03 (40707)
│ │ │ │ +845B6 Filename Length       0018 (24)
│ │ │ │ +845B8 Extra Length          001C (28)
│ │ │ │ +845BA Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x845BA: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +845D2 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +845D4   Length              0009 (9)
│ │ │ │ +845D6   Flags               03 (3) 'Modification Access'
│ │ │ │ +845D7   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +845DB   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +845DF Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +845E1   Length              000B (11)
│ │ │ │ +845E3   Version             01 (1)
│ │ │ │ +845E4   UID Size            04 (4)
│ │ │ │ +845E5   UID                 00000000 (0)
│ │ │ │ +845E9   GID Size            04 (4)
│ │ │ │ +845EA   GID                 00000000 (0)
│ │ │ │ +845EE PAYLOAD
│ │ │ │ +
│ │ │ │ +86179 LOCAL HEADER #76      04034B50 (67324752)
│ │ │ │ +8617D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +8617E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +8617F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +86181 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +86183 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +86187 CRC                   59BB50F3 (1505448179)
│ │ │ │ +8618B Compressed Size       000016F9 (5881)
│ │ │ │ +8618F Uncompressed Size     00008AB6 (35510)
│ │ │ │ +86193 Filename Length       0012 (18)
│ │ │ │ +86195 Extra Length          001C (28)
│ │ │ │ +86197 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x86197: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +861A9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +861AB   Length              0009 (9)
│ │ │ │ +861AD   Flags               03 (3) 'Modification Access'
│ │ │ │ +861AE   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +861B2   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +861B6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +861B8   Length              000B (11)
│ │ │ │ +861BA   Version             01 (1)
│ │ │ │ +861BB   UID Size            04 (4)
│ │ │ │ +861BC   UID                 00000000 (0)
│ │ │ │ +861C0   GID Size            04 (4)
│ │ │ │ +861C1   GID                 00000000 (0)
│ │ │ │ +861C5 PAYLOAD
│ │ │ │ +
│ │ │ │ +878BE LOCAL HEADER #77      04034B50 (67324752)
│ │ │ │ +878C2 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +878C3 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +878C4 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +878C6 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +878C8 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +878CC CRC                   EA21F703 (3928094467)
│ │ │ │ +878D0 Compressed Size       00001E13 (7699)
│ │ │ │ +878D4 Uncompressed Size     00008803 (34819)
│ │ │ │ +878D8 Filename Length       0016 (22)
│ │ │ │ +878DA Extra Length          001C (28)
│ │ │ │ +878DC Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x878DC: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +878F2 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +878F4   Length              0009 (9)
│ │ │ │ +878F6   Flags               03 (3) 'Modification Access'
│ │ │ │ +878F7   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +878FB   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +878FF Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +87901   Length              000B (11)
│ │ │ │ +87903   Version             01 (1)
│ │ │ │ +87904   UID Size            04 (4)
│ │ │ │ +87905   UID                 00000000 (0)
│ │ │ │ +87909   GID Size            04 (4)
│ │ │ │ +8790A   GID                 00000000 (0)
│ │ │ │ +8790E PAYLOAD
│ │ │ │ +
│ │ │ │ +89721 LOCAL HEADER #78      04034B50 (67324752)
│ │ │ │ +89725 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +89726 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +89727 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +89729 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +8972B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8972F CRC                   F5D80FF6 (4124577782)
│ │ │ │ +89733 Compressed Size       000029A8 (10664)
│ │ │ │ +89737 Uncompressed Size     0000D04F (53327)
│ │ │ │ +8973B Filename Length       001A (26)
│ │ │ │ +8973D Extra Length          001C (28)
│ │ │ │ +8973F Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x8973F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +89759 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +8975B   Length              0009 (9)
│ │ │ │ +8975D   Flags               03 (3) 'Modification Access'
│ │ │ │ +8975E   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +89762   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +89766 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +89768   Length              000B (11)
│ │ │ │ +8976A   Version             01 (1)
│ │ │ │ +8976B   UID Size            04 (4)
│ │ │ │ +8976C   UID                 00000000 (0)
│ │ │ │ +89770   GID Size            04 (4)
│ │ │ │ +89771   GID                 00000000 (0)
│ │ │ │ +89775 PAYLOAD
│ │ │ │ +
│ │ │ │ +8C11D LOCAL HEADER #79      04034B50 (67324752)
│ │ │ │ +8C121 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +8C122 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +8C123 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +8C125 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +8C127 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8C12B CRC                   B50D8ED4 (3037564628)
│ │ │ │ +8C12F Compressed Size       000009AC (2476)
│ │ │ │ +8C133 Uncompressed Size     00001DB6 (7606)
│ │ │ │ +8C137 Filename Length       0018 (24)
│ │ │ │ +8C139 Extra Length          001C (28)
│ │ │ │ +8C13B Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x8C13B: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +8C153 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +8C155   Length              0009 (9)
│ │ │ │ +8C157   Flags               03 (3) 'Modification Access'
│ │ │ │ +8C158   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8C15C   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8C160 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +8C162   Length              000B (11)
│ │ │ │ +8C164   Version             01 (1)
│ │ │ │ +8C165   UID Size            04 (4)
│ │ │ │ +8C166   UID                 00000000 (0)
│ │ │ │ +8C16A   GID Size            04 (4)
│ │ │ │ +8C16B   GID                 00000000 (0)
│ │ │ │ +8C16F PAYLOAD
│ │ │ │ +
│ │ │ │ +8CB1B LOCAL HEADER #80      04034B50 (67324752)
│ │ │ │ +8CB1F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +8CB20 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +8CB21 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +8CB23 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +8CB25 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8CB29 CRC                   F5E2129F (4125233823)
│ │ │ │ +8CB2D Compressed Size       000016BC (5820)
│ │ │ │ +8CB31 Uncompressed Size     000016CD (5837)
│ │ │ │ +8CB35 Filename Length       0015 (21)
│ │ │ │ +8CB37 Extra Length          001C (28)
│ │ │ │ +8CB39 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x8CB39: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +8CB4E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +8CB50   Length              0009 (9)
│ │ │ │ +8CB52   Flags               03 (3) 'Modification Access'
│ │ │ │ +8CB53   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8CB57   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8CB5B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +8CB5D   Length              000B (11)
│ │ │ │ +8CB5F   Version             01 (1)
│ │ │ │ +8CB60   UID Size            04 (4)
│ │ │ │ +8CB61   UID                 00000000 (0)
│ │ │ │ +8CB65   GID Size            04 (4)
│ │ │ │ +8CB66   GID                 00000000 (0)
│ │ │ │ +8CB6A PAYLOAD
│ │ │ │ +
│ │ │ │ +8E226 LOCAL HEADER #81      04034B50 (67324752)
│ │ │ │ +8E22A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +8E22B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +8E22C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +8E22E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +8E230 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8E234 CRC                   F5E2129F (4125233823)
│ │ │ │ +8E238 Compressed Size       000016BC (5820)
│ │ │ │ +8E23C Uncompressed Size     000016CD (5837)
│ │ │ │ +8E240 Filename Length       001C (28)
│ │ │ │ +8E242 Extra Length          001C (28)
│ │ │ │ +8E244 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x8E244: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +8E260 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +8E262   Length              0009 (9)
│ │ │ │ +8E264   Flags               03 (3) 'Modification Access'
│ │ │ │ +8E265   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8E269   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8E26D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +8E26F   Length              000B (11)
│ │ │ │ +8E271   Version             01 (1)
│ │ │ │ +8E272   UID Size            04 (4)
│ │ │ │ +8E273   UID                 00000000 (0)
│ │ │ │ +8E277   GID Size            04 (4)
│ │ │ │ +8E278   GID                 00000000 (0)
│ │ │ │ +8E27C PAYLOAD
│ │ │ │ +
│ │ │ │ +8F938 LOCAL HEADER #82      04034B50 (67324752)
│ │ │ │ +8F93C Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +8F93D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +8F93E General Purpose Flag  0000 (0)
│ │ │ │ +8F940 Compression Method    0000 (0) 'Stored'
│ │ │ │ +8F942 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8F946 CRC                   FC95F24B (4237685323)
│ │ │ │ +8F94A Compressed Size       00001B84 (7044)
│ │ │ │ +8F94E Uncompressed Size     00001B84 (7044)
│ │ │ │ +8F952 Filename Length       0016 (22)
│ │ │ │ +8F954 Extra Length          001C (28)
│ │ │ │ +8F956 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x8F956: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +8F96C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +8F96E   Length              0009 (9)
│ │ │ │ +8F970   Flags               03 (3) 'Modification Access'
│ │ │ │ +8F971   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8F975   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +8F979 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +8F97B   Length              000B (11)
│ │ │ │ +8F97D   Version             01 (1)
│ │ │ │ +8F97E   UID Size            04 (4)
│ │ │ │ +8F97F   UID                 00000000 (0)
│ │ │ │ +8F983   GID Size            04 (4)
│ │ │ │ +8F984   GID                 00000000 (0)
│ │ │ │ +8F988 PAYLOAD
│ │ │ │ +
│ │ │ │ +9150C LOCAL HEADER #83      04034B50 (67324752)
│ │ │ │ +91510 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +91511 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +91512 General Purpose Flag  0000 (0)
│ │ │ │ +91514 Compression Method    0000 (0) 'Stored'
│ │ │ │ +91516 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9151A CRC                   D0D71F86 (3503759238)
│ │ │ │ +9151E Compressed Size       00000B7B (2939)
│ │ │ │ +91522 Uncompressed Size     00000B7B (2939)
│ │ │ │ +91526 Filename Length       0016 (22)
│ │ │ │ +91528 Extra Length          001C (28)
│ │ │ │ +9152A Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9152A: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +91540 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +91542   Length              0009 (9)
│ │ │ │ +91544   Flags               03 (3) 'Modification Access'
│ │ │ │ +91545   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +91549   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9154D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9154F   Length              000B (11)
│ │ │ │ +91551   Version             01 (1)
│ │ │ │ +91552   UID Size            04 (4)
│ │ │ │ +91553   UID                 00000000 (0)
│ │ │ │ +91557   GID Size            04 (4)
│ │ │ │ +91558   GID                 00000000 (0)
│ │ │ │ +9155C PAYLOAD
│ │ │ │ +
│ │ │ │ +920D7 LOCAL HEADER #84      04034B50 (67324752)
│ │ │ │ +920DB Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +920DC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +920DD General Purpose Flag  0000 (0)
│ │ │ │ +920DF Compression Method    0000 (0) 'Stored'
│ │ │ │ +920E1 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +920E5 CRC                   FFF9C4D2 (4294558930)
│ │ │ │ +920E9 Compressed Size       0000138F (5007)
│ │ │ │ +920ED Uncompressed Size     0000138F (5007)
│ │ │ │ +920F1 Filename Length       0016 (22)
│ │ │ │ +920F3 Extra Length          001C (28)
│ │ │ │ +920F5 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x920F5: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9210B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9210D   Length              0009 (9)
│ │ │ │ +9210F   Flags               03 (3) 'Modification Access'
│ │ │ │ +92110   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +92114   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +92118 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9211A   Length              000B (11)
│ │ │ │ +9211C   Version             01 (1)
│ │ │ │ +9211D   UID Size            04 (4)
│ │ │ │ +9211E   UID                 00000000 (0)
│ │ │ │ +92122   GID Size            04 (4)
│ │ │ │ +92123   GID                 00000000 (0)
│ │ │ │ +92127 PAYLOAD
│ │ │ │ +
│ │ │ │ +934B6 LOCAL HEADER #85      04034B50 (67324752)
│ │ │ │ +934BA Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +934BB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +934BC General Purpose Flag  0000 (0)
│ │ │ │ +934BE Compression Method    0000 (0) 'Stored'
│ │ │ │ +934C0 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +934C4 CRC                   A1037E8E (2701360782)
│ │ │ │ +934C8 Compressed Size       0000145E (5214)
│ │ │ │ +934CC Uncompressed Size     0000145E (5214)
│ │ │ │ +934D0 Filename Length       0016 (22)
│ │ │ │ +934D2 Extra Length          001C (28)
│ │ │ │ +934D4 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x934D4: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +934EA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +934EC   Length              0009 (9)
│ │ │ │ +934EE   Flags               03 (3) 'Modification Access'
│ │ │ │ +934EF   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +934F3   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +934F7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +934F9   Length              000B (11)
│ │ │ │ +934FB   Version             01 (1)
│ │ │ │ +934FC   UID Size            04 (4)
│ │ │ │ +934FD   UID                 00000000 (0)
│ │ │ │ +93501   GID Size            04 (4)
│ │ │ │ +93502   GID                 00000000 (0)
│ │ │ │ +93506 PAYLOAD
│ │ │ │ +
│ │ │ │ +94964 LOCAL HEADER #86      04034B50 (67324752)
│ │ │ │ +94968 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +94969 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9496A General Purpose Flag  0000 (0)
│ │ │ │ +9496C Compression Method    0000 (0) 'Stored'
│ │ │ │ +9496E Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +94972 CRC                   5E9E64F1 (1587438833)
│ │ │ │ +94976 Compressed Size       000008EC (2284)
│ │ │ │ +9497A Uncompressed Size     000008EC (2284)
│ │ │ │ +9497E Filename Length       0016 (22)
│ │ │ │ +94980 Extra Length          001C (28)
│ │ │ │ +94982 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x94982: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +94998 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9499A   Length              0009 (9)
│ │ │ │ +9499C   Flags               03 (3) 'Modification Access'
│ │ │ │ +9499D   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +949A1   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +949A5 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +949A7   Length              000B (11)
│ │ │ │ +949A9   Version             01 (1)
│ │ │ │ +949AA   UID Size            04 (4)
│ │ │ │ +949AB   UID                 00000000 (0)
│ │ │ │ +949AF   GID Size            04 (4)
│ │ │ │ +949B0   GID                 00000000 (0)
│ │ │ │ +949B4 PAYLOAD
│ │ │ │ +
│ │ │ │ +952A0 LOCAL HEADER #87      04034B50 (67324752)
│ │ │ │ +952A4 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +952A5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +952A6 General Purpose Flag  0000 (0)
│ │ │ │ +952A8 Compression Method    0000 (0) 'Stored'
│ │ │ │ +952AA Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +952AE CRC                   42E340AB (1122189483)
│ │ │ │ +952B2 Compressed Size       00001F2E (7982)
│ │ │ │ +952B6 Uncompressed Size     00001F2E (7982)
│ │ │ │ +952BA Filename Length       001E (30)
│ │ │ │ +952BC Extra Length          001C (28)
│ │ │ │ +952BE Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x952BE: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +952DC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +952DE   Length              0009 (9)
│ │ │ │ +952E0   Flags               03 (3) 'Modification Access'
│ │ │ │ +952E1   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +952E5   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +952E9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +952EB   Length              000B (11)
│ │ │ │ +952ED   Version             01 (1)
│ │ │ │ +952EE   UID Size            04 (4)
│ │ │ │ +952EF   UID                 00000000 (0)
│ │ │ │ +952F3   GID Size            04 (4)
│ │ │ │ +952F4   GID                 00000000 (0)
│ │ │ │ +952F8 PAYLOAD
│ │ │ │ +
│ │ │ │ +97226 LOCAL HEADER #88      04034B50 (67324752)
│ │ │ │ +9722A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9722B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9722C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9722E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +97230 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +97234 CRC                   A35733FC (2740401148)
│ │ │ │ +97238 Compressed Size       00003D72 (15730)
│ │ │ │ +9723C Uncompressed Size     00016649 (91721)
│ │ │ │ +97240 Filename Length       001A (26)
│ │ │ │ +97242 Extra Length          001C (28)
│ │ │ │ +97244 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x97244: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9725E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +97260   Length              0009 (9)
│ │ │ │ +97262   Flags               03 (3) 'Modification Access'
│ │ │ │ +97263   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +97267   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9726B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9726D   Length              000B (11)
│ │ │ │ +9726F   Version             01 (1)
│ │ │ │ +97270   UID Size            04 (4)
│ │ │ │ +97271   UID                 00000000 (0)
│ │ │ │ +97275   GID Size            04 (4)
│ │ │ │ +97276   GID                 00000000 (0)
│ │ │ │ +9727A PAYLOAD
│ │ │ │ +
│ │ │ │ +9AFEC LOCAL HEADER #89      04034B50 (67324752)
│ │ │ │ +9AFF0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9AFF1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9AFF2 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9AFF4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9AFF6 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9AFFA CRC                   FC5489FE (4233398782)
│ │ │ │ +9AFFE Compressed Size       000029BD (10685)
│ │ │ │ +9B002 Uncompressed Size     0000BA6A (47722)
│ │ │ │ +9B006 Filename Length       0018 (24)
│ │ │ │ +9B008 Extra Length          001C (28)
│ │ │ │ +9B00A Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9B00A: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9B022 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9B024   Length              0009 (9)
│ │ │ │ +9B026   Flags               03 (3) 'Modification Access'
│ │ │ │ +9B027   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9B02B   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9B02F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9B031   Length              000B (11)
│ │ │ │ +9B033   Version             01 (1)
│ │ │ │ +9B034   UID Size            04 (4)
│ │ │ │ +9B035   UID                 00000000 (0)
│ │ │ │ +9B039   GID Size            04 (4)
│ │ │ │ +9B03A   GID                 00000000 (0)
│ │ │ │ +9B03E PAYLOAD
│ │ │ │ +
│ │ │ │ +9D9FB LOCAL HEADER #90      04034B50 (67324752)
│ │ │ │ +9D9FF Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DA00 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DA01 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DA03 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DA05 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DA09 CRC                   DCB3B516 (3702764822)
│ │ │ │ +9DA0D Compressed Size       000000AE (174)
│ │ │ │ +9DA11 Uncompressed Size     000000FC (252)
│ │ │ │ +9DA15 Filename Length       0016 (22)
│ │ │ │ +9DA17 Extra Length          001C (28)
│ │ │ │ +9DA19 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DA19: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DA2F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DA31   Length              0009 (9)
│ │ │ │ +9DA33   Flags               03 (3) 'Modification Access'
│ │ │ │ +9DA34   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DA38   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DA3C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DA3E   Length              000B (11)
│ │ │ │ +9DA40   Version             01 (1)
│ │ │ │ +9DA41   UID Size            04 (4)
│ │ │ │ +9DA42   UID                 00000000 (0)
│ │ │ │ +9DA46   GID Size            04 (4)
│ │ │ │ +9DA47   GID                 00000000 (0)
│ │ │ │ +9DA4B PAYLOAD               XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
│ │ │ │                              XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
│ │ │ │  
│ │ │ │ -9DAD4 LOCAL HEADER #91      04034B50 (67324752)
│ │ │ │ -9DAD8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DAD9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DADA General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DADC Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DADE Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DAE2 CRC                   58439733 (1480824627)
│ │ │ │ -9DAE6 Compressed Size       00000077 (119)
│ │ │ │ -9DAEA Uncompressed Size     000000A2 (162)
│ │ │ │ -9DAEE Filename Length       002D (45)
│ │ │ │ -9DAF0 Extra Length          001C (28)
│ │ │ │ -9DAF2 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DAF2: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DB1F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DB21   Length              0009 (9)
│ │ │ │ -9DB23   Flags               03 (3) 'Modification Access'
│ │ │ │ -9DB24   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DB28   Access Time         6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DB2C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DB2E   Length              000B (11)
│ │ │ │ -9DB30   Version             01 (1)
│ │ │ │ -9DB31   UID Size            04 (4)
│ │ │ │ -9DB32   UID                 00000000 (0)
│ │ │ │ -9DB36   GID Size            04 (4)
│ │ │ │ -9DB37   GID                 00000000 (0)
│ │ │ │ -9DB3B PAYLOAD               XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
│ │ │ │ -
│ │ │ │ -9DBB2 CENTRAL HEADER #1     02014B50 (33639248)
│ │ │ │ -9DBB6 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DBB7 Created OS            03 (3) 'Unix'
│ │ │ │ -9DBB8 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9DBB9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DBBA General Purpose Flag  0000 (0)
│ │ │ │ -9DBBC Compression Method    0000 (0) 'Stored'
│ │ │ │ -9DBBE Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DBC2 CRC                   2CAB616F (749429103)
│ │ │ │ -9DBC6 Compressed Size       00000014 (20)
│ │ │ │ -9DBCA Uncompressed Size     00000014 (20)
│ │ │ │ -9DBCE Filename Length       0008 (8)
│ │ │ │ -9DBD0 Extra Length          0018 (24)
│ │ │ │ -9DBD2 Comment Length        0000 (0)
│ │ │ │ -9DBD4 Disk Start            0000 (0)
│ │ │ │ -9DBD6 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DBD8 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DBDC Local Header Offset   00000000 (0)
│ │ │ │ -9DBE0 Filename              'XXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DBE0: Filename 'XXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DBE8 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DBEA   Length              0005 (5)
│ │ │ │ -9DBEC   Flags               01 (1) 'Modification'
│ │ │ │ -9DBED   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DBF1 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DBF3   Length              000B (11)
│ │ │ │ -9DBF5   Version             01 (1)
│ │ │ │ -9DBF6   UID Size            04 (4)
│ │ │ │ -9DBF7   UID                 00000000 (0)
│ │ │ │ -9DBFB   GID Size            04 (4)
│ │ │ │ -9DBFC   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DC00 CENTRAL HEADER #2     02014B50 (33639248)
│ │ │ │ -9DC04 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DC05 Created OS            03 (3) 'Unix'
│ │ │ │ -9DC06 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DC07 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DC08 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DC0A Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DC0C Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DC10 CRC                   203D4469 (540886121)
│ │ │ │ -9DC14 Compressed Size       000015AD (5549)
│ │ │ │ -9DC18 Uncompressed Size     00004602 (17922)
│ │ │ │ -9DC1C Filename Length       0014 (20)
│ │ │ │ -9DC1E Extra Length          0018 (24)
│ │ │ │ -9DC20 Comment Length        0000 (0)
│ │ │ │ -9DC22 Disk Start            0000 (0)
│ │ │ │ -9DC24 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DC26 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DC2A Local Header Offset   00000056 (86)
│ │ │ │ -9DC2E Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DC2E: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DC42 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DC44   Length              0005 (5)
│ │ │ │ -9DC46   Flags               01 (1) 'Modification'
│ │ │ │ -9DC47   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DC4B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DC4D   Length              000B (11)
│ │ │ │ -9DC4F   Version             01 (1)
│ │ │ │ -9DC50   UID Size            04 (4)
│ │ │ │ -9DC51   UID                 00000000 (0)
│ │ │ │ -9DC55   GID Size            04 (4)
│ │ │ │ -9DC56   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DC5A CENTRAL HEADER #3     02014B50 (33639248)
│ │ │ │ -9DC5E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DC5F Created OS            03 (3) 'Unix'
│ │ │ │ -9DC60 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DC61 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DC62 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DC64 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DC66 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DC6A CRC                   1EC1D7C5 (516020165)
│ │ │ │ -9DC6E Compressed Size       000006D5 (1749)
│ │ │ │ -9DC72 Uncompressed Size     00001241 (4673)
│ │ │ │ -9DC76 Filename Length       0013 (19)
│ │ │ │ -9DC78 Extra Length          0018 (24)
│ │ │ │ -9DC7A Comment Length        0000 (0)
│ │ │ │ -9DC7C Disk Start            0000 (0)
│ │ │ │ -9DC7E Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DC80 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DC84 Local Header Offset   00001651 (5713)
│ │ │ │ -9DC88 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DC88: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DC9B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DC9D   Length              0005 (5)
│ │ │ │ -9DC9F   Flags               01 (1) 'Modification'
│ │ │ │ -9DCA0   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DCA4 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DCA6   Length              000B (11)
│ │ │ │ -9DCA8   Version             01 (1)
│ │ │ │ -9DCA9   UID Size            04 (4)
│ │ │ │ -9DCAA   UID                 00000000 (0)
│ │ │ │ -9DCAE   GID Size            04 (4)
│ │ │ │ -9DCAF   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DCB3 CENTRAL HEADER #4     02014B50 (33639248)
│ │ │ │ -9DCB7 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DCB8 Created OS            03 (3) 'Unix'
│ │ │ │ -9DCB9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DCBA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DCBB General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DCBD Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DCBF Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DCC3 CRC                   DD59CFB1 (3713650609)
│ │ │ │ -9DCC7 Compressed Size       00002DA9 (11689)
│ │ │ │ -9DCCB Uncompressed Size     0000D0BF (53439)
│ │ │ │ -9DCCF Filename Length       0014 (20)
│ │ │ │ -9DCD1 Extra Length          0018 (24)
│ │ │ │ -9DCD3 Comment Length        0000 (0)
│ │ │ │ -9DCD5 Disk Start            0000 (0)
│ │ │ │ -9DCD7 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DCD9 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DCDD Local Header Offset   00001D73 (7539)
│ │ │ │ -9DCE1 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DCE1: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DCF5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DCF7   Length              0005 (5)
│ │ │ │ -9DCF9   Flags               01 (1) 'Modification'
│ │ │ │ -9DCFA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DCFE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DD00   Length              000B (11)
│ │ │ │ -9DD02   Version             01 (1)
│ │ │ │ -9DD03   UID Size            04 (4)
│ │ │ │ -9DD04   UID                 00000000 (0)
│ │ │ │ -9DD08   GID Size            04 (4)
│ │ │ │ -9DD09   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DD0D CENTRAL HEADER #5     02014B50 (33639248)
│ │ │ │ -9DD11 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DD12 Created OS            03 (3) 'Unix'
│ │ │ │ -9DD13 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DD14 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DD15 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DD17 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DD19 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DD1D CRC                   B8F4A452 (3103040594)
│ │ │ │ -9DD21 Compressed Size       000003F0 (1008)
│ │ │ │ -9DD25 Uncompressed Size     00000876 (2166)
│ │ │ │ -9DD29 Filename Length       0014 (20)
│ │ │ │ -9DD2B Extra Length          0018 (24)
│ │ │ │ -9DD2D Comment Length        0000 (0)
│ │ │ │ -9DD2F Disk Start            0000 (0)
│ │ │ │ -9DD31 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DD33 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DD37 Local Header Offset   00004B6A (19306)
│ │ │ │ -9DD3B Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DD3B: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DD4F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DD51   Length              0005 (5)
│ │ │ │ -9DD53   Flags               01 (1) 'Modification'
│ │ │ │ -9DD54   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DD58 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DD5A   Length              000B (11)
│ │ │ │ -9DD5C   Version             01 (1)
│ │ │ │ -9DD5D   UID Size            04 (4)
│ │ │ │ -9DD5E   UID                 00000000 (0)
│ │ │ │ -9DD62   GID Size            04 (4)
│ │ │ │ -9DD63   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DD67 CENTRAL HEADER #6     02014B50 (33639248)
│ │ │ │ -9DD6B Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DD6C Created OS            03 (3) 'Unix'
│ │ │ │ -9DD6D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DD6E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DD6F General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DD71 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DD73 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DD77 CRC                   D32DA388 (3542983560)
│ │ │ │ -9DD7B Compressed Size       000001AE (430)
│ │ │ │ -9DD7F Uncompressed Size     000002FC (764)
│ │ │ │ -9DD83 Filename Length       0011 (17)
│ │ │ │ -9DD85 Extra Length          0018 (24)
│ │ │ │ -9DD87 Comment Length        0000 (0)
│ │ │ │ -9DD89 Disk Start            0000 (0)
│ │ │ │ -9DD8B Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DD8D Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DD91 Local Header Offset   00004FA8 (20392)
│ │ │ │ -9DD95 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DD95: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DDA6 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DDA8   Length              0005 (5)
│ │ │ │ -9DDAA   Flags               01 (1) 'Modification'
│ │ │ │ -9DDAB   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DDAF Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DDB1   Length              000B (11)
│ │ │ │ -9DDB3   Version             01 (1)
│ │ │ │ -9DDB4   UID Size            04 (4)
│ │ │ │ -9DDB5   UID                 00000000 (0)
│ │ │ │ -9DDB9   GID Size            04 (4)
│ │ │ │ -9DDBA   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DDBE CENTRAL HEADER #7     02014B50 (33639248)
│ │ │ │ -9DDC2 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DDC3 Created OS            03 (3) 'Unix'
│ │ │ │ -9DDC4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DDC5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DDC6 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DDC8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DDCA Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DDCE CRC                   D5BF807E (3586097278)
│ │ │ │ -9DDD2 Compressed Size       000020C6 (8390)
│ │ │ │ -9DDD6 Uncompressed Size     0000B4B0 (46256)
│ │ │ │ -9DDDA Filename Length       001B (27)
│ │ │ │ -9DDDC Extra Length          0018 (24)
│ │ │ │ -9DDDE Comment Length        0000 (0)
│ │ │ │ -9DDE0 Disk Start            0000 (0)
│ │ │ │ -9DDE2 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DDE4 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DDE8 Local Header Offset   000051A1 (20897)
│ │ │ │ -9DDEC Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DDEC: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DE07 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DE09   Length              0005 (5)
│ │ │ │ -9DE0B   Flags               01 (1) 'Modification'
│ │ │ │ -9DE0C   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DE10 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DE12   Length              000B (11)
│ │ │ │ -9DE14   Version             01 (1)
│ │ │ │ -9DE15   UID Size            04 (4)
│ │ │ │ -9DE16   UID                 00000000 (0)
│ │ │ │ -9DE1A   GID Size            04 (4)
│ │ │ │ -9DE1B   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DE1F CENTRAL HEADER #8     02014B50 (33639248)
│ │ │ │ -9DE23 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DE24 Created OS            03 (3) 'Unix'
│ │ │ │ -9DE25 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DE26 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DE27 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DE29 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DE2B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DE2F CRC                   CB35CCED (3409300717)
│ │ │ │ -9DE33 Compressed Size       00000E6F (3695)
│ │ │ │ -9DE37 Uncompressed Size     000030B2 (12466)
│ │ │ │ -9DE3B Filename Length       001D (29)
│ │ │ │ -9DE3D Extra Length          0018 (24)
│ │ │ │ -9DE3F Comment Length        0000 (0)
│ │ │ │ -9DE41 Disk Start            0000 (0)
│ │ │ │ -9DE43 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DE45 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DE49 Local Header Offset   000072BC (29372)
│ │ │ │ -9DE4D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DE4D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DE6A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DE6C   Length              0005 (5)
│ │ │ │ -9DE6E   Flags               01 (1) 'Modification'
│ │ │ │ -9DE6F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DE73 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DE75   Length              000B (11)
│ │ │ │ -9DE77   Version             01 (1)
│ │ │ │ -9DE78   UID Size            04 (4)
│ │ │ │ -9DE79   UID                 00000000 (0)
│ │ │ │ -9DE7D   GID Size            04 (4)
│ │ │ │ -9DE7E   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DE82 CENTRAL HEADER #9     02014B50 (33639248)
│ │ │ │ -9DE86 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DE87 Created OS            03 (3) 'Unix'
│ │ │ │ -9DE88 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DE89 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DE8A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DE8C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DE8E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DE92 CRC                   D01F57B3 (3491714995)
│ │ │ │ -9DE96 Compressed Size       00000972 (2418)
│ │ │ │ -9DE9A Uncompressed Size     00001CB2 (7346)
│ │ │ │ -9DE9E Filename Length       0019 (25)
│ │ │ │ -9DEA0 Extra Length          0018 (24)
│ │ │ │ -9DEA2 Comment Length        0000 (0)
│ │ │ │ -9DEA4 Disk Start            0000 (0)
│ │ │ │ -9DEA6 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DEA8 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DEAC Local Header Offset   00008182 (33154)
│ │ │ │ -9DEB0 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DEB0: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DEC9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DECB   Length              0005 (5)
│ │ │ │ -9DECD   Flags               01 (1) 'Modification'
│ │ │ │ -9DECE   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DED2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DED4   Length              000B (11)
│ │ │ │ -9DED6   Version             01 (1)
│ │ │ │ -9DED7   UID Size            04 (4)
│ │ │ │ -9DED8   UID                 00000000 (0)
│ │ │ │ -9DEDC   GID Size            04 (4)
│ │ │ │ -9DEDD   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DEE1 CENTRAL HEADER #10    02014B50 (33639248)
│ │ │ │ -9DEE5 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DEE6 Created OS            03 (3) 'Unix'
│ │ │ │ -9DEE7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DEE8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DEE9 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DEEB Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DEED Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DEF1 CRC                   92DCCD7D (2463944061)
│ │ │ │ -9DEF5 Compressed Size       0000387F (14463)
│ │ │ │ -9DEF9 Uncompressed Size     0000F7F4 (63476)
│ │ │ │ -9DEFD Filename Length       0015 (21)
│ │ │ │ -9DEFF Extra Length          0018 (24)
│ │ │ │ -9DF01 Comment Length        0000 (0)
│ │ │ │ -9DF03 Disk Start            0000 (0)
│ │ │ │ -9DF05 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DF07 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DF0B Local Header Offset   00008B47 (35655)
│ │ │ │ -9DF0F Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DF0F: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DF24 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DF26   Length              0005 (5)
│ │ │ │ -9DF28   Flags               01 (1) 'Modification'
│ │ │ │ -9DF29   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DF2D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DF2F   Length              000B (11)
│ │ │ │ -9DF31   Version             01 (1)
│ │ │ │ -9DF32   UID Size            04 (4)
│ │ │ │ -9DF33   UID                 00000000 (0)
│ │ │ │ -9DF37   GID Size            04 (4)
│ │ │ │ -9DF38   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DF3C CENTRAL HEADER #11    02014B50 (33639248)
│ │ │ │ -9DF40 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DF41 Created OS            03 (3) 'Unix'
│ │ │ │ -9DF42 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DF43 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DF44 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DF46 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DF48 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DF4C CRC                   2368599F (594041247)
│ │ │ │ -9DF50 Compressed Size       0000AAD3 (43731)
│ │ │ │ -9DF54 Uncompressed Size     0003DFDE (253918)
│ │ │ │ -9DF58 Filename Length       0012 (18)
│ │ │ │ -9DF5A Extra Length          0018 (24)
│ │ │ │ -9DF5C Comment Length        0000 (0)
│ │ │ │ -9DF5E Disk Start            0000 (0)
│ │ │ │ -9DF60 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DF62 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DF66 Local Header Offset   0000C415 (50197)
│ │ │ │ -9DF6A Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DF6A: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DF7C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DF7E   Length              0005 (5)
│ │ │ │ -9DF80   Flags               01 (1) 'Modification'
│ │ │ │ -9DF81   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DF85 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DF87   Length              000B (11)
│ │ │ │ -9DF89   Version             01 (1)
│ │ │ │ -9DF8A   UID Size            04 (4)
│ │ │ │ -9DF8B   UID                 00000000 (0)
│ │ │ │ -9DF8F   GID Size            04 (4)
│ │ │ │ -9DF90   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DF94 CENTRAL HEADER #12    02014B50 (33639248)
│ │ │ │ -9DF98 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DF99 Created OS            03 (3) 'Unix'
│ │ │ │ -9DF9A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DF9B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DF9C General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DF9E Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DFA0 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DFA4 CRC                   2DEC84BF (770475199)
│ │ │ │ -9DFA8 Compressed Size       00003B1E (15134)
│ │ │ │ -9DFAC Uncompressed Size     0001B2A0 (111264)
│ │ │ │ -9DFB0 Filename Length       0015 (21)
│ │ │ │ -9DFB2 Extra Length          0018 (24)
│ │ │ │ -9DFB4 Comment Length        0000 (0)
│ │ │ │ -9DFB6 Disk Start            0000 (0)
│ │ │ │ -9DFB8 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9DFBA Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9DFBE Local Header Offset   00016F34 (94004)
│ │ │ │ -9DFC2 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9DFC2: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9DFD7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9DFD9   Length              0005 (5)
│ │ │ │ -9DFDB   Flags               01 (1) 'Modification'
│ │ │ │ -9DFDC   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9DFE0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9DFE2   Length              000B (11)
│ │ │ │ -9DFE4   Version             01 (1)
│ │ │ │ -9DFE5   UID Size            04 (4)
│ │ │ │ -9DFE6   UID                 00000000 (0)
│ │ │ │ -9DFEA   GID Size            04 (4)
│ │ │ │ -9DFEB   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9DFEF CENTRAL HEADER #13    02014B50 (33639248)
│ │ │ │ -9DFF3 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9DFF4 Created OS            03 (3) 'Unix'
│ │ │ │ -9DFF5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9DFF6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9DFF7 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9DFF9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9DFFB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9DFFF CRC                   352F19D3 (892279251)
│ │ │ │ -9E003 Compressed Size       00009090 (37008)
│ │ │ │ -9E007 Uncompressed Size     0003D05F (249951)
│ │ │ │ -9E00B Filename Length       0014 (20)
│ │ │ │ -9E00D Extra Length          0018 (24)
│ │ │ │ -9E00F Comment Length        0000 (0)
│ │ │ │ -9E011 Disk Start            0000 (0)
│ │ │ │ -9E013 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E015 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E019 Local Header Offset   0001AAA1 (109217)
│ │ │ │ -9E01D Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E01D: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E031 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E033   Length              0005 (5)
│ │ │ │ -9E035   Flags               01 (1) 'Modification'
│ │ │ │ -9E036   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E03A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E03C   Length              000B (11)
│ │ │ │ -9E03E   Version             01 (1)
│ │ │ │ -9E03F   UID Size            04 (4)
│ │ │ │ -9E040   UID                 00000000 (0)
│ │ │ │ -9E044   GID Size            04 (4)
│ │ │ │ -9E045   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E049 CENTRAL HEADER #14    02014B50 (33639248)
│ │ │ │ -9E04D Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E04E Created OS            03 (3) 'Unix'
│ │ │ │ -9E04F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E050 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E051 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E053 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E055 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E059 CRC                   A14752A3 (2705805987)
│ │ │ │ -9E05D Compressed Size       00002A65 (10853)
│ │ │ │ -9E061 Uncompressed Size     0001151F (70943)
│ │ │ │ -9E065 Filename Length       0016 (22)
│ │ │ │ -9E067 Extra Length          0018 (24)
│ │ │ │ -9E069 Comment Length        0000 (0)
│ │ │ │ -9E06B Disk Start            0000 (0)
│ │ │ │ -9E06D Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E06F Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E073 Local Header Offset   00023B7F (146303)
│ │ │ │ -9E077 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E077: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E08D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E08F   Length              0005 (5)
│ │ │ │ -9E091   Flags               01 (1) 'Modification'
│ │ │ │ -9E092   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E096 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E098   Length              000B (11)
│ │ │ │ -9E09A   Version             01 (1)
│ │ │ │ -9E09B   UID Size            04 (4)
│ │ │ │ -9E09C   UID                 00000000 (0)
│ │ │ │ -9E0A0   GID Size            04 (4)
│ │ │ │ -9E0A1   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E0A5 CENTRAL HEADER #15    02014B50 (33639248)
│ │ │ │ -9E0A9 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E0AA Created OS            03 (3) 'Unix'
│ │ │ │ -9E0AB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E0AC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E0AD General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E0AF Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E0B1 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E0B5 CRC                   F1E18143 (4058087747)
│ │ │ │ -9E0B9 Compressed Size       000014D8 (5336)
│ │ │ │ -9E0BD Uncompressed Size     00005176 (20854)
│ │ │ │ -9E0C1 Filename Length       001D (29)
│ │ │ │ -9E0C3 Extra Length          0018 (24)
│ │ │ │ -9E0C5 Comment Length        0000 (0)
│ │ │ │ -9E0C7 Disk Start            0000 (0)
│ │ │ │ -9E0C9 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E0CB Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E0CF Local Header Offset   00026634 (157236)
│ │ │ │ -9E0D3 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E0D3: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E0F0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E0F2   Length              0005 (5)
│ │ │ │ -9E0F4   Flags               01 (1) 'Modification'
│ │ │ │ -9E0F5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E0F9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E0FB   Length              000B (11)
│ │ │ │ -9E0FD   Version             01 (1)
│ │ │ │ -9E0FE   UID Size            04 (4)
│ │ │ │ -9E0FF   UID                 00000000 (0)
│ │ │ │ -9E103   GID Size            04 (4)
│ │ │ │ -9E104   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E108 CENTRAL HEADER #16    02014B50 (33639248)
│ │ │ │ -9E10C Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E10D Created OS            03 (3) 'Unix'
│ │ │ │ -9E10E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E10F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E110 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E112 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E114 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E118 CRC                   78898277 (2022277751)
│ │ │ │ -9E11C Compressed Size       000037F6 (14326)
│ │ │ │ -9E120 Uncompressed Size     0000E9F0 (59888)
│ │ │ │ -9E124 Filename Length       001C (28)
│ │ │ │ -9E126 Extra Length          0018 (24)
│ │ │ │ -9E128 Comment Length        0000 (0)
│ │ │ │ -9E12A Disk Start            0000 (0)
│ │ │ │ -9E12C Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E12E Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E132 Local Header Offset   00027B63 (162659)
│ │ │ │ -9E136 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E136: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E152 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E154   Length              0005 (5)
│ │ │ │ -9E156   Flags               01 (1) 'Modification'
│ │ │ │ -9E157   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E15B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E15D   Length              000B (11)
│ │ │ │ -9E15F   Version             01 (1)
│ │ │ │ -9E160   UID Size            04 (4)
│ │ │ │ -9E161   UID                 00000000 (0)
│ │ │ │ -9E165   GID Size            04 (4)
│ │ │ │ -9E166   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E16A CENTRAL HEADER #17    02014B50 (33639248)
│ │ │ │ -9E16E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E16F Created OS            03 (3) 'Unix'
│ │ │ │ -9E170 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E171 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E172 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E174 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E176 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E17A CRC                   6A63C5E7 (1784923623)
│ │ │ │ -9E17E Compressed Size       000006A0 (1696)
│ │ │ │ -9E182 Uncompressed Size     000011F4 (4596)
│ │ │ │ -9E186 Filename Length       001C (28)
│ │ │ │ -9E188 Extra Length          0018 (24)
│ │ │ │ -9E18A Comment Length        0000 (0)
│ │ │ │ -9E18C Disk Start            0000 (0)
│ │ │ │ -9E18E Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E190 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E194 Local Header Offset   0002B3AF (177071)
│ │ │ │ -9E198 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E198: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E1B4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E1B6   Length              0005 (5)
│ │ │ │ -9E1B8   Flags               01 (1) 'Modification'
│ │ │ │ -9E1B9   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E1BD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E1BF   Length              000B (11)
│ │ │ │ -9E1C1   Version             01 (1)
│ │ │ │ -9E1C2   UID Size            04 (4)
│ │ │ │ -9E1C3   UID                 00000000 (0)
│ │ │ │ -9E1C7   GID Size            04 (4)
│ │ │ │ -9E1C8   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E1CC CENTRAL HEADER #18    02014B50 (33639248)
│ │ │ │ -9E1D0 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E1D1 Created OS            03 (3) 'Unix'
│ │ │ │ -9E1D2 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E1D3 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E1D4 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E1D6 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E1D8 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E1DC CRC                   4B420ADA (1262619354)
│ │ │ │ -9E1E0 Compressed Size       0000107B (4219)
│ │ │ │ -9E1E4 Uncompressed Size     00004BFF (19455)
│ │ │ │ -9E1E8 Filename Length       001B (27)
│ │ │ │ -9E1EA Extra Length          0018 (24)
│ │ │ │ -9E1EC Comment Length        0000 (0)
│ │ │ │ -9E1EE Disk Start            0000 (0)
│ │ │ │ -9E1F0 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E1F2 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E1F6 Local Header Offset   0002BAA5 (178853)
│ │ │ │ -9E1FA Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E1FA: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E215 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E217   Length              0005 (5)
│ │ │ │ -9E219   Flags               01 (1) 'Modification'
│ │ │ │ -9E21A   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E21E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E220   Length              000B (11)
│ │ │ │ -9E222   Version             01 (1)
│ │ │ │ -9E223   UID Size            04 (4)
│ │ │ │ -9E224   UID                 00000000 (0)
│ │ │ │ -9E228   GID Size            04 (4)
│ │ │ │ -9E229   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E22D CENTRAL HEADER #19    02014B50 (33639248)
│ │ │ │ -9E231 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E232 Created OS            03 (3) 'Unix'
│ │ │ │ -9E233 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E234 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E235 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E237 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E239 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E23D CRC                   A579921F (2776207903)
│ │ │ │ -9E241 Compressed Size       000033AB (13227)
│ │ │ │ -9E245 Uncompressed Size     0000BC94 (48276)
│ │ │ │ -9E249 Filename Length       001D (29)
│ │ │ │ -9E24B Extra Length          0018 (24)
│ │ │ │ -9E24D Comment Length        0000 (0)
│ │ │ │ -9E24F Disk Start            0000 (0)
│ │ │ │ -9E251 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E253 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E257 Local Header Offset   0002CB75 (183157)
│ │ │ │ -9E25B Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E25B: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E278 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E27A   Length              0005 (5)
│ │ │ │ -9E27C   Flags               01 (1) 'Modification'
│ │ │ │ -9E27D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E281 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E283   Length              000B (11)
│ │ │ │ -9E285   Version             01 (1)
│ │ │ │ -9E286   UID Size            04 (4)
│ │ │ │ -9E287   UID                 00000000 (0)
│ │ │ │ -9E28B   GID Size            04 (4)
│ │ │ │ -9E28C   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E290 CENTRAL HEADER #20    02014B50 (33639248)
│ │ │ │ -9E294 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E295 Created OS            03 (3) 'Unix'
│ │ │ │ -9E296 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E297 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E298 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E29A Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E29C Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E2A0 CRC                   3BBA297E (1002056062)
│ │ │ │ -9E2A4 Compressed Size       00000D6C (3436)
│ │ │ │ -9E2A8 Uncompressed Size     00003876 (14454)
│ │ │ │ -9E2AC Filename Length       001D (29)
│ │ │ │ -9E2AE Extra Length          0018 (24)
│ │ │ │ -9E2B0 Comment Length        0000 (0)
│ │ │ │ -9E2B2 Disk Start            0000 (0)
│ │ │ │ -9E2B4 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E2B6 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E2BA Local Header Offset   0002FF77 (196471)
│ │ │ │ -9E2BE Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E2BE: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E2DB Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E2DD   Length              0005 (5)
│ │ │ │ -9E2DF   Flags               01 (1) 'Modification'
│ │ │ │ -9E2E0   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E2E4 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E2E6   Length              000B (11)
│ │ │ │ -9E2E8   Version             01 (1)
│ │ │ │ -9E2E9   UID Size            04 (4)
│ │ │ │ -9E2EA   UID                 00000000 (0)
│ │ │ │ -9E2EE   GID Size            04 (4)
│ │ │ │ -9E2EF   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E2F3 CENTRAL HEADER #21    02014B50 (33639248)
│ │ │ │ -9E2F7 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E2F8 Created OS            03 (3) 'Unix'
│ │ │ │ -9E2F9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E2FA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E2FB General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E2FD Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E2FF Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E303 CRC                   CE4502E0 (3460629216)
│ │ │ │ -9E307 Compressed Size       00001C6A (7274)
│ │ │ │ -9E30B Uncompressed Size     0000C186 (49542)
│ │ │ │ -9E30F Filename Length       001A (26)
│ │ │ │ -9E311 Extra Length          0018 (24)
│ │ │ │ -9E313 Comment Length        0000 (0)
│ │ │ │ -9E315 Disk Start            0000 (0)
│ │ │ │ -9E317 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E319 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E31D Local Header Offset   00030D3A (199994)
│ │ │ │ -9E321 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E321: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E33B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E33D   Length              0005 (5)
│ │ │ │ -9E33F   Flags               01 (1) 'Modification'
│ │ │ │ -9E340   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E344 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E346   Length              000B (11)
│ │ │ │ -9E348   Version             01 (1)
│ │ │ │ -9E349   UID Size            04 (4)
│ │ │ │ -9E34A   UID                 00000000 (0)
│ │ │ │ -9E34E   GID Size            04 (4)
│ │ │ │ -9E34F   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E353 CENTRAL HEADER #22    02014B50 (33639248)
│ │ │ │ -9E357 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E358 Created OS            03 (3) 'Unix'
│ │ │ │ -9E359 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E35A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E35B General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E35D Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E35F Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E363 CRC                   65574916 (1700219158)
│ │ │ │ -9E367 Compressed Size       000003A3 (931)
│ │ │ │ -9E36B Uncompressed Size     0000088E (2190)
│ │ │ │ -9E36F Filename Length       0012 (18)
│ │ │ │ -9E371 Extra Length          0018 (24)
│ │ │ │ -9E373 Comment Length        0000 (0)
│ │ │ │ -9E375 Disk Start            0000 (0)
│ │ │ │ -9E377 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E379 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E37D Local Header Offset   000329F8 (207352)
│ │ │ │ -9E381 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E381: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E393 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E395   Length              0005 (5)
│ │ │ │ -9E397   Flags               01 (1) 'Modification'
│ │ │ │ -9E398   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E39C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E39E   Length              000B (11)
│ │ │ │ -9E3A0   Version             01 (1)
│ │ │ │ -9E3A1   UID Size            04 (4)
│ │ │ │ -9E3A2   UID                 00000000 (0)
│ │ │ │ -9E3A6   GID Size            04 (4)
│ │ │ │ -9E3A7   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E3AB CENTRAL HEADER #23    02014B50 (33639248)
│ │ │ │ -9E3AF Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E3B0 Created OS            03 (3) 'Unix'
│ │ │ │ -9E3B1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E3B2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E3B3 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E3B5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E3B7 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E3BB CRC                   83472134 (2202476852)
│ │ │ │ -9E3BF Compressed Size       000001D4 (468)
│ │ │ │ -9E3C3 Uncompressed Size     00000311 (785)
│ │ │ │ -9E3C7 Filename Length       0020 (32)
│ │ │ │ -9E3C9 Extra Length          0018 (24)
│ │ │ │ -9E3CB Comment Length        0000 (0)
│ │ │ │ -9E3CD Disk Start            0000 (0)
│ │ │ │ -9E3CF Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E3D1 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E3D5 Local Header Offset   00032DE7 (208359)
│ │ │ │ -9E3D9 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E3D9: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E3F9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E3FB   Length              0005 (5)
│ │ │ │ -9E3FD   Flags               01 (1) 'Modification'
│ │ │ │ -9E3FE   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E402 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E404   Length              000B (11)
│ │ │ │ -9E406   Version             01 (1)
│ │ │ │ -9E407   UID Size            04 (4)
│ │ │ │ -9E408   UID                 00000000 (0)
│ │ │ │ -9E40C   GID Size            04 (4)
│ │ │ │ -9E40D   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E411 CENTRAL HEADER #24    02014B50 (33639248)
│ │ │ │ -9E415 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E416 Created OS            03 (3) 'Unix'
│ │ │ │ -9E417 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E418 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E419 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E41B Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E41D Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E421 CRC                   E5289043 (3844640835)
│ │ │ │ -9E425 Compressed Size       000017A7 (6055)
│ │ │ │ -9E429 Uncompressed Size     00009CD3 (40147)
│ │ │ │ -9E42D Filename Length       001B (27)
│ │ │ │ -9E42F Extra Length          0018 (24)
│ │ │ │ -9E431 Comment Length        0000 (0)
│ │ │ │ -9E433 Disk Start            0000 (0)
│ │ │ │ -9E435 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E437 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E43B Local Header Offset   00033015 (208917)
│ │ │ │ -9E43F Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E43F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E45A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E45C   Length              0005 (5)
│ │ │ │ -9E45E   Flags               01 (1) 'Modification'
│ │ │ │ -9E45F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E463 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E465   Length              000B (11)
│ │ │ │ -9E467   Version             01 (1)
│ │ │ │ -9E468   UID Size            04 (4)
│ │ │ │ -9E469   UID                 00000000 (0)
│ │ │ │ -9E46D   GID Size            04 (4)
│ │ │ │ -9E46E   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E472 CENTRAL HEADER #25    02014B50 (33639248)
│ │ │ │ -9E476 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E477 Created OS            03 (3) 'Unix'
│ │ │ │ -9E478 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E479 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E47A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E47C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E47E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E482 CRC                   5F73B5AE (1601418670)
│ │ │ │ -9E486 Compressed Size       00001371 (4977)
│ │ │ │ -9E48A Uncompressed Size     00003B66 (15206)
│ │ │ │ -9E48E Filename Length       0015 (21)
│ │ │ │ -9E490 Extra Length          0018 (24)
│ │ │ │ -9E492 Comment Length        0000 (0)
│ │ │ │ -9E494 Disk Start            0000 (0)
│ │ │ │ -9E496 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E498 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E49C Local Header Offset   00034811 (215057)
│ │ │ │ -9E4A0 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E4A0: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E4B5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E4B7   Length              0005 (5)
│ │ │ │ -9E4B9   Flags               01 (1) 'Modification'
│ │ │ │ -9E4BA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E4BE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E4C0   Length              000B (11)
│ │ │ │ -9E4C2   Version             01 (1)
│ │ │ │ -9E4C3   UID Size            04 (4)
│ │ │ │ -9E4C4   UID                 00000000 (0)
│ │ │ │ -9E4C8   GID Size            04 (4)
│ │ │ │ -9E4C9   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E4CD CENTRAL HEADER #26    02014B50 (33639248)
│ │ │ │ -9E4D1 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E4D2 Created OS            03 (3) 'Unix'
│ │ │ │ -9E4D3 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E4D4 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E4D5 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E4D7 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E4D9 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E4DD CRC                   7FAE09B6 (2142112182)
│ │ │ │ -9E4E1 Compressed Size       00000AD1 (2769)
│ │ │ │ -9E4E5 Uncompressed Size     00002135 (8501)
│ │ │ │ -9E4E9 Filename Length       0011 (17)
│ │ │ │ -9E4EB Extra Length          0018 (24)
│ │ │ │ -9E4ED Comment Length        0000 (0)
│ │ │ │ -9E4EF Disk Start            0000 (0)
│ │ │ │ -9E4F1 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E4F3 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E4F7 Local Header Offset   00035BD1 (220113)
│ │ │ │ -9E4FB Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E4FB: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E50C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E50E   Length              0005 (5)
│ │ │ │ -9E510   Flags               01 (1) 'Modification'
│ │ │ │ -9E511   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E515 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E517   Length              000B (11)
│ │ │ │ -9E519   Version             01 (1)
│ │ │ │ -9E51A   UID Size            04 (4)
│ │ │ │ -9E51B   UID                 00000000 (0)
│ │ │ │ -9E51F   GID Size            04 (4)
│ │ │ │ -9E520   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E524 CENTRAL HEADER #27    02014B50 (33639248)
│ │ │ │ -9E528 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E529 Created OS            03 (3) 'Unix'
│ │ │ │ -9E52A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E52B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E52C General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E52E Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E530 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E534 CRC                   F2F690A2 (4076245154)
│ │ │ │ -9E538 Compressed Size       000003FE (1022)
│ │ │ │ -9E53C Uncompressed Size     00000E99 (3737)
│ │ │ │ -9E540 Filename Length       0014 (20)
│ │ │ │ -9E542 Extra Length          0018 (24)
│ │ │ │ -9E544 Comment Length        0000 (0)
│ │ │ │ -9E546 Disk Start            0000 (0)
│ │ │ │ -9E548 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E54A Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E54E Local Header Offset   000366ED (222957)
│ │ │ │ -9E552 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E552: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E566 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E568   Length              0005 (5)
│ │ │ │ -9E56A   Flags               01 (1) 'Modification'
│ │ │ │ -9E56B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E56F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E571   Length              000B (11)
│ │ │ │ -9E573   Version             01 (1)
│ │ │ │ -9E574   UID Size            04 (4)
│ │ │ │ -9E575   UID                 00000000 (0)
│ │ │ │ -9E579   GID Size            04 (4)
│ │ │ │ -9E57A   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E57E CENTRAL HEADER #28    02014B50 (33639248)
│ │ │ │ -9E582 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E583 Created OS            03 (3) 'Unix'
│ │ │ │ -9E584 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E585 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E586 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E588 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E58A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E58E CRC                   EB83ACB7 (3951275191)
│ │ │ │ -9E592 Compressed Size       00001261 (4705)
│ │ │ │ -9E596 Uncompressed Size     00003469 (13417)
│ │ │ │ -9E59A Filename Length       0014 (20)
│ │ │ │ -9E59C Extra Length          0018 (24)
│ │ │ │ -9E59E Comment Length        0000 (0)
│ │ │ │ -9E5A0 Disk Start            0000 (0)
│ │ │ │ -9E5A2 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E5A4 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E5A8 Local Header Offset   00036B39 (224057)
│ │ │ │ -9E5AC Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E5AC: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E5C0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E5C2   Length              0005 (5)
│ │ │ │ -9E5C4   Flags               01 (1) 'Modification'
│ │ │ │ -9E5C5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E5C9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E5CB   Length              000B (11)
│ │ │ │ -9E5CD   Version             01 (1)
│ │ │ │ -9E5CE   UID Size            04 (4)
│ │ │ │ -9E5CF   UID                 00000000 (0)
│ │ │ │ -9E5D3   GID Size            04 (4)
│ │ │ │ -9E5D4   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E5D8 CENTRAL HEADER #29    02014B50 (33639248)
│ │ │ │ -9E5DC Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E5DD Created OS            03 (3) 'Unix'
│ │ │ │ -9E5DE Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E5DF Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E5E0 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E5E2 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E5E4 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E5E8 CRC                   ED6E01D4 (3983409620)
│ │ │ │ -9E5EC Compressed Size       00000AD0 (2768)
│ │ │ │ -9E5F0 Uncompressed Size     000022FF (8959)
│ │ │ │ -9E5F4 Filename Length       001B (27)
│ │ │ │ -9E5F6 Extra Length          0018 (24)
│ │ │ │ -9E5F8 Comment Length        0000 (0)
│ │ │ │ -9E5FA Disk Start            0000 (0)
│ │ │ │ -9E5FC Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E5FE Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E602 Local Header Offset   00037DE8 (228840)
│ │ │ │ -9E606 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E606: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E621 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E623   Length              0005 (5)
│ │ │ │ -9E625   Flags               01 (1) 'Modification'
│ │ │ │ -9E626   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E62A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E62C   Length              000B (11)
│ │ │ │ -9E62E   Version             01 (1)
│ │ │ │ -9E62F   UID Size            04 (4)
│ │ │ │ -9E630   UID                 00000000 (0)
│ │ │ │ -9E634   GID Size            04 (4)
│ │ │ │ -9E635   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E639 CENTRAL HEADER #30    02014B50 (33639248)
│ │ │ │ -9E63D Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E63E Created OS            03 (3) 'Unix'
│ │ │ │ -9E63F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E640 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E641 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E643 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E645 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E649 CRC                   7FE9699A (2146003354)
│ │ │ │ -9E64D Compressed Size       00000A8D (2701)
│ │ │ │ -9E651 Uncompressed Size     0000237A (9082)
│ │ │ │ -9E655 Filename Length       0013 (19)
│ │ │ │ -9E657 Extra Length          0018 (24)
│ │ │ │ -9E659 Comment Length        0000 (0)
│ │ │ │ -9E65B Disk Start            0000 (0)
│ │ │ │ -9E65D Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E65F Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E663 Local Header Offset   0003890D (231693)
│ │ │ │ -9E667 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E667: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E67A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E67C   Length              0005 (5)
│ │ │ │ -9E67E   Flags               01 (1) 'Modification'
│ │ │ │ -9E67F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E683 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E685   Length              000B (11)
│ │ │ │ -9E687   Version             01 (1)
│ │ │ │ -9E688   UID Size            04 (4)
│ │ │ │ -9E689   UID                 00000000 (0)
│ │ │ │ -9E68D   GID Size            04 (4)
│ │ │ │ -9E68E   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E692 CENTRAL HEADER #31    02014B50 (33639248)
│ │ │ │ -9E696 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E697 Created OS            03 (3) 'Unix'
│ │ │ │ -9E698 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E699 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E69A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E69C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E69E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E6A2 CRC                   DD9D1818 (3718060056)
│ │ │ │ -9E6A6 Compressed Size       00000F48 (3912)
│ │ │ │ -9E6AA Uncompressed Size     000036F1 (14065)
│ │ │ │ -9E6AE Filename Length       000F (15)
│ │ │ │ -9E6B0 Extra Length          0018 (24)
│ │ │ │ -9E6B2 Comment Length        0000 (0)
│ │ │ │ -9E6B4 Disk Start            0000 (0)
│ │ │ │ -9E6B6 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E6B8 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E6BC Local Header Offset   000393E7 (234471)
│ │ │ │ -9E6C0 Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E6C0: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E6CF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E6D1   Length              0005 (5)
│ │ │ │ -9E6D3   Flags               01 (1) 'Modification'
│ │ │ │ -9E6D4   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E6D8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E6DA   Length              000B (11)
│ │ │ │ -9E6DC   Version             01 (1)
│ │ │ │ -9E6DD   UID Size            04 (4)
│ │ │ │ -9E6DE   UID                 00000000 (0)
│ │ │ │ -9E6E2   GID Size            04 (4)
│ │ │ │ -9E6E3   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E6E7 CENTRAL HEADER #32    02014B50 (33639248)
│ │ │ │ -9E6EB Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E6EC Created OS            03 (3) 'Unix'
│ │ │ │ -9E6ED Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E6EE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E6EF General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E6F1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E6F3 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E6F7 CRC                   54672E6E (1416048238)
│ │ │ │ -9E6FB Compressed Size       0000066A (1642)
│ │ │ │ -9E6FF Uncompressed Size     000018DF (6367)
│ │ │ │ -9E703 Filename Length       000F (15)
│ │ │ │ -9E705 Extra Length          0018 (24)
│ │ │ │ -9E707 Comment Length        0000 (0)
│ │ │ │ -9E709 Disk Start            0000 (0)
│ │ │ │ -9E70B Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E70D Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E711 Local Header Offset   0003A378 (238456)
│ │ │ │ -9E715 Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E715: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E724 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E726   Length              0005 (5)
│ │ │ │ -9E728   Flags               01 (1) 'Modification'
│ │ │ │ -9E729   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E72D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E72F   Length              000B (11)
│ │ │ │ -9E731   Version             01 (1)
│ │ │ │ -9E732   UID Size            04 (4)
│ │ │ │ -9E733   UID                 00000000 (0)
│ │ │ │ -9E737   GID Size            04 (4)
│ │ │ │ -9E738   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E73C CENTRAL HEADER #33    02014B50 (33639248)
│ │ │ │ -9E740 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E741 Created OS            03 (3) 'Unix'
│ │ │ │ -9E742 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E743 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E744 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E746 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E748 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E74C CRC                   8AF71E36 (2331450934)
│ │ │ │ -9E750 Compressed Size       00001A49 (6729)
│ │ │ │ -9E754 Uncompressed Size     000064F2 (25842)
│ │ │ │ -9E758 Filename Length       0013 (19)
│ │ │ │ -9E75A Extra Length          0018 (24)
│ │ │ │ -9E75C Comment Length        0000 (0)
│ │ │ │ -9E75E Disk Start            0000 (0)
│ │ │ │ -9E760 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E762 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E766 Local Header Offset   0003AA2B (240171)
│ │ │ │ -9E76A Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E76A: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E77D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E77F   Length              0005 (5)
│ │ │ │ -9E781   Flags               01 (1) 'Modification'
│ │ │ │ -9E782   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E786 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E788   Length              000B (11)
│ │ │ │ -9E78A   Version             01 (1)
│ │ │ │ -9E78B   UID Size            04 (4)
│ │ │ │ -9E78C   UID                 00000000 (0)
│ │ │ │ -9E790   GID Size            04 (4)
│ │ │ │ -9E791   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E795 CENTRAL HEADER #34    02014B50 (33639248)
│ │ │ │ -9E799 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E79A Created OS            03 (3) 'Unix'
│ │ │ │ -9E79B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E79C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E79D General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E79F Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E7A1 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E7A5 CRC                   D1448544 (3510928708)
│ │ │ │ -9E7A9 Compressed Size       000009A5 (2469)
│ │ │ │ -9E7AD Uncompressed Size     00001B64 (7012)
│ │ │ │ -9E7B1 Filename Length       0010 (16)
│ │ │ │ -9E7B3 Extra Length          0018 (24)
│ │ │ │ -9E7B5 Comment Length        0000 (0)
│ │ │ │ -9E7B7 Disk Start            0000 (0)
│ │ │ │ -9E7B9 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E7BB Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E7BF Local Header Offset   0003C4C1 (246977)
│ │ │ │ -9E7C3 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E7C3: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E7D3 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E7D5   Length              0005 (5)
│ │ │ │ -9E7D7   Flags               01 (1) 'Modification'
│ │ │ │ -9E7D8   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E7DC Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E7DE   Length              000B (11)
│ │ │ │ -9E7E0   Version             01 (1)
│ │ │ │ -9E7E1   UID Size            04 (4)
│ │ │ │ -9E7E2   UID                 00000000 (0)
│ │ │ │ -9E7E6   GID Size            04 (4)
│ │ │ │ -9E7E7   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E7EB CENTRAL HEADER #35    02014B50 (33639248)
│ │ │ │ -9E7EF Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E7F0 Created OS            03 (3) 'Unix'
│ │ │ │ -9E7F1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E7F2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E7F3 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E7F5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E7F7 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E7FB CRC                   3E5AEB62 (1046145890)
│ │ │ │ -9E7FF Compressed Size       000006B7 (1719)
│ │ │ │ -9E803 Uncompressed Size     00001565 (5477)
│ │ │ │ -9E807 Filename Length       0012 (18)
│ │ │ │ -9E809 Extra Length          0018 (24)
│ │ │ │ -9E80B Comment Length        0000 (0)
│ │ │ │ -9E80D Disk Start            0000 (0)
│ │ │ │ -9E80F Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E811 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E815 Local Header Offset   0003CEB0 (249520)
│ │ │ │ -9E819 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E819: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E82B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E82D   Length              0005 (5)
│ │ │ │ -9E82F   Flags               01 (1) 'Modification'
│ │ │ │ -9E830   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E834 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E836   Length              000B (11)
│ │ │ │ -9E838   Version             01 (1)
│ │ │ │ -9E839   UID Size            04 (4)
│ │ │ │ -9E83A   UID                 00000000 (0)
│ │ │ │ -9E83E   GID Size            04 (4)
│ │ │ │ -9E83F   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E843 CENTRAL HEADER #36    02014B50 (33639248)
│ │ │ │ -9E847 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E848 Created OS            03 (3) 'Unix'
│ │ │ │ -9E849 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E84A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E84B General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E84D Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E84F Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E853 CRC                   C50CE88C (3305957516)
│ │ │ │ -9E857 Compressed Size       00002A1A (10778)
│ │ │ │ -9E85B Uncompressed Size     0000B1C5 (45509)
│ │ │ │ -9E85F Filename Length       0010 (16)
│ │ │ │ -9E861 Extra Length          0018 (24)
│ │ │ │ -9E863 Comment Length        0000 (0)
│ │ │ │ -9E865 Disk Start            0000 (0)
│ │ │ │ -9E867 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E869 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E86D Local Header Offset   0003D5B3 (251315)
│ │ │ │ -9E871 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E871: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E881 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E883   Length              0005 (5)
│ │ │ │ -9E885   Flags               01 (1) 'Modification'
│ │ │ │ -9E886   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E88A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E88C   Length              000B (11)
│ │ │ │ -9E88E   Version             01 (1)
│ │ │ │ -9E88F   UID Size            04 (4)
│ │ │ │ -9E890   UID                 00000000 (0)
│ │ │ │ -9E894   GID Size            04 (4)
│ │ │ │ -9E895   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E899 CENTRAL HEADER #37    02014B50 (33639248)
│ │ │ │ -9E89D Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E89E Created OS            03 (3) 'Unix'
│ │ │ │ -9E89F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E8A0 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E8A1 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E8A3 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E8A5 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E8A9 CRC                   C59A1802 (3315210242)
│ │ │ │ -9E8AD Compressed Size       00001E84 (7812)
│ │ │ │ -9E8B1 Uncompressed Size     00009AAA (39594)
│ │ │ │ -9E8B5 Filename Length       0012 (18)
│ │ │ │ -9E8B7 Extra Length          0018 (24)
│ │ │ │ -9E8B9 Comment Length        0000 (0)
│ │ │ │ -9E8BB Disk Start            0000 (0)
│ │ │ │ -9E8BD Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E8BF Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E8C3 Local Header Offset   00040017 (262167)
│ │ │ │ -9E8C7 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E8C7: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E8D9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E8DB   Length              0005 (5)
│ │ │ │ -9E8DD   Flags               01 (1) 'Modification'
│ │ │ │ -9E8DE   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E8E2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E8E4   Length              000B (11)
│ │ │ │ -9E8E6   Version             01 (1)
│ │ │ │ -9E8E7   UID Size            04 (4)
│ │ │ │ -9E8E8   UID                 00000000 (0)
│ │ │ │ -9E8EC   GID Size            04 (4)
│ │ │ │ -9E8ED   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E8F1 CENTRAL HEADER #38    02014B50 (33639248)
│ │ │ │ -9E8F5 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E8F6 Created OS            03 (3) 'Unix'
│ │ │ │ -9E8F7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E8F8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E8F9 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E8FB Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E8FD Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E901 CRC                   A34909C0 (2739472832)
│ │ │ │ -9E905 Compressed Size       00001477 (5239)
│ │ │ │ -9E909 Uncompressed Size     00007ACF (31439)
│ │ │ │ -9E90D Filename Length       0018 (24)
│ │ │ │ -9E90F Extra Length          0018 (24)
│ │ │ │ -9E911 Comment Length        0000 (0)
│ │ │ │ -9E913 Disk Start            0000 (0)
│ │ │ │ -9E915 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E917 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E91B Local Header Offset   00041EE7 (270055)
│ │ │ │ -9E91F Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E91F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E937 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E939   Length              0005 (5)
│ │ │ │ -9E93B   Flags               01 (1) 'Modification'
│ │ │ │ -9E93C   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E940 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E942   Length              000B (11)
│ │ │ │ -9E944   Version             01 (1)
│ │ │ │ -9E945   UID Size            04 (4)
│ │ │ │ -9E946   UID                 00000000 (0)
│ │ │ │ -9E94A   GID Size            04 (4)
│ │ │ │ -9E94B   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E94F CENTRAL HEADER #39    02014B50 (33639248)
│ │ │ │ -9E953 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E954 Created OS            03 (3) 'Unix'
│ │ │ │ -9E955 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E956 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E957 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E959 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E95B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E95F CRC                   C605A326 (3322258214)
│ │ │ │ -9E963 Compressed Size       000018CF (6351)
│ │ │ │ -9E967 Uncompressed Size     0000A7F4 (42996)
│ │ │ │ -9E96B Filename Length       001F (31)
│ │ │ │ -9E96D Extra Length          0018 (24)
│ │ │ │ -9E96F Comment Length        0000 (0)
│ │ │ │ -9E971 Disk Start            0000 (0)
│ │ │ │ -9E973 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E975 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E979 Local Header Offset   000433B0 (275376)
│ │ │ │ -9E97D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E97D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9E99C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9E99E   Length              0005 (5)
│ │ │ │ -9E9A0   Flags               01 (1) 'Modification'
│ │ │ │ -9E9A1   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9E9A5 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9E9A7   Length              000B (11)
│ │ │ │ -9E9A9   Version             01 (1)
│ │ │ │ -9E9AA   UID Size            04 (4)
│ │ │ │ -9E9AB   UID                 00000000 (0)
│ │ │ │ -9E9AF   GID Size            04 (4)
│ │ │ │ -9E9B0   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9E9B4 CENTRAL HEADER #40    02014B50 (33639248)
│ │ │ │ -9E9B8 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9E9B9 Created OS            03 (3) 'Unix'
│ │ │ │ -9E9BA Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9E9BB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9E9BC General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9E9BE Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9E9C0 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9E9C4 CRC                   FFAF198F (4289665423)
│ │ │ │ -9E9C8 Compressed Size       000003F6 (1014)
│ │ │ │ -9E9CC Uncompressed Size     000008A3 (2211)
│ │ │ │ -9E9D0 Filename Length       001E (30)
│ │ │ │ -9E9D2 Extra Length          0018 (24)
│ │ │ │ -9E9D4 Comment Length        0000 (0)
│ │ │ │ -9E9D6 Disk Start            0000 (0)
│ │ │ │ -9E9D8 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9E9DA Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9E9DE Local Header Offset   00044CD8 (281816)
│ │ │ │ -9E9E2 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9E9E2: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EA00 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EA02   Length              0005 (5)
│ │ │ │ -9EA04   Flags               01 (1) 'Modification'
│ │ │ │ -9EA05   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EA09 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EA0B   Length              000B (11)
│ │ │ │ -9EA0D   Version             01 (1)
│ │ │ │ -9EA0E   UID Size            04 (4)
│ │ │ │ -9EA0F   UID                 00000000 (0)
│ │ │ │ -9EA13   GID Size            04 (4)
│ │ │ │ -9EA14   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EA18 CENTRAL HEADER #41    02014B50 (33639248)
│ │ │ │ -9EA1C Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EA1D Created OS            03 (3) 'Unix'
│ │ │ │ -9EA1E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EA1F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EA20 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EA22 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EA24 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EA28 CRC                   32E3FA13 (853801491)
│ │ │ │ -9EA2C Compressed Size       00004292 (17042)
│ │ │ │ -9EA30 Uncompressed Size     0000D8DC (55516)
│ │ │ │ -9EA34 Filename Length       0013 (19)
│ │ │ │ -9EA36 Extra Length          0018 (24)
│ │ │ │ -9EA38 Comment Length        0000 (0)
│ │ │ │ -9EA3A Disk Start            0000 (0)
│ │ │ │ -9EA3C Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EA3E Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EA42 Local Header Offset   00045126 (282918)
│ │ │ │ -9EA46 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EA46: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EA59 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EA5B   Length              0005 (5)
│ │ │ │ -9EA5D   Flags               01 (1) 'Modification'
│ │ │ │ -9EA5E   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EA62 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EA64   Length              000B (11)
│ │ │ │ -9EA66   Version             01 (1)
│ │ │ │ -9EA67   UID Size            04 (4)
│ │ │ │ -9EA68   UID                 00000000 (0)
│ │ │ │ -9EA6C   GID Size            04 (4)
│ │ │ │ -9EA6D   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EA71 CENTRAL HEADER #42    02014B50 (33639248)
│ │ │ │ -9EA75 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EA76 Created OS            03 (3) 'Unix'
│ │ │ │ -9EA77 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EA78 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EA79 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EA7B Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EA7D Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EA81 CRC                   9F6AFEBF (2674589375)
│ │ │ │ -9EA85 Compressed Size       000026C3 (9923)
│ │ │ │ -9EA89 Uncompressed Size     00006E45 (28229)
│ │ │ │ -9EA8D Filename Length       0019 (25)
│ │ │ │ -9EA8F Extra Length          0018 (24)
│ │ │ │ -9EA91 Comment Length        0000 (0)
│ │ │ │ -9EA93 Disk Start            0000 (0)
│ │ │ │ -9EA95 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EA97 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EA9B Local Header Offset   00049405 (300037)
│ │ │ │ -9EA9F Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EA9F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EAB8 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EABA   Length              0005 (5)
│ │ │ │ -9EABC   Flags               01 (1) 'Modification'
│ │ │ │ -9EABD   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EAC1 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EAC3   Length              000B (11)
│ │ │ │ -9EAC5   Version             01 (1)
│ │ │ │ -9EAC6   UID Size            04 (4)
│ │ │ │ -9EAC7   UID                 00000000 (0)
│ │ │ │ -9EACB   GID Size            04 (4)
│ │ │ │ -9EACC   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EAD0 CENTRAL HEADER #43    02014B50 (33639248)
│ │ │ │ -9EAD4 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EAD5 Created OS            03 (3) 'Unix'
│ │ │ │ -9EAD6 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EAD7 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EAD8 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EADA Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EADC Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EAE0 CRC                   0369577C (57235324)
│ │ │ │ -9EAE4 Compressed Size       00002739 (10041)
│ │ │ │ -9EAE8 Uncompressed Size     00008B83 (35715)
│ │ │ │ -9EAEC Filename Length       0019 (25)
│ │ │ │ -9EAEE Extra Length          0018 (24)
│ │ │ │ -9EAF0 Comment Length        0000 (0)
│ │ │ │ -9EAF2 Disk Start            0000 (0)
│ │ │ │ -9EAF4 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EAF6 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EAFA Local Header Offset   0004BB1B (310043)
│ │ │ │ -9EAFE Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EAFE: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EB17 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EB19   Length              0005 (5)
│ │ │ │ -9EB1B   Flags               01 (1) 'Modification'
│ │ │ │ -9EB1C   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EB20 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EB22   Length              000B (11)
│ │ │ │ -9EB24   Version             01 (1)
│ │ │ │ -9EB25   UID Size            04 (4)
│ │ │ │ -9EB26   UID                 00000000 (0)
│ │ │ │ -9EB2A   GID Size            04 (4)
│ │ │ │ -9EB2B   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EB2F CENTRAL HEADER #44    02014B50 (33639248)
│ │ │ │ -9EB33 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EB34 Created OS            03 (3) 'Unix'
│ │ │ │ -9EB35 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EB36 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EB37 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EB39 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EB3B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EB3F CRC                   8B9BB6EF (2342237935)
│ │ │ │ -9EB43 Compressed Size       00000CF1 (3313)
│ │ │ │ -9EB47 Uncompressed Size     0000517A (20858)
│ │ │ │ -9EB4B Filename Length       0021 (33)
│ │ │ │ -9EB4D Extra Length          0018 (24)
│ │ │ │ -9EB4F Comment Length        0000 (0)
│ │ │ │ -9EB51 Disk Start            0000 (0)
│ │ │ │ -9EB53 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EB55 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EB59 Local Header Offset   0004E2A7 (320167)
│ │ │ │ -9EB5D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EB5D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EB7E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EB80   Length              0005 (5)
│ │ │ │ -9EB82   Flags               01 (1) 'Modification'
│ │ │ │ -9EB83   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EB87 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EB89   Length              000B (11)
│ │ │ │ -9EB8B   Version             01 (1)
│ │ │ │ -9EB8C   UID Size            04 (4)
│ │ │ │ -9EB8D   UID                 00000000 (0)
│ │ │ │ -9EB91   GID Size            04 (4)
│ │ │ │ -9EB92   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EB96 CENTRAL HEADER #45    02014B50 (33639248)
│ │ │ │ -9EB9A Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EB9B Created OS            03 (3) 'Unix'
│ │ │ │ -9EB9C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EB9D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EB9E General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EBA0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EBA2 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EBA6 CRC                   8F01E69C (2399266460)
│ │ │ │ -9EBAA Compressed Size       00000468 (1128)
│ │ │ │ -9EBAE Uncompressed Size     00000931 (2353)
│ │ │ │ -9EBB2 Filename Length       001B (27)
│ │ │ │ -9EBB4 Extra Length          0018 (24)
│ │ │ │ -9EBB6 Comment Length        0000 (0)
│ │ │ │ -9EBB8 Disk Start            0000 (0)
│ │ │ │ -9EBBA Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EBBC Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EBC0 Local Header Offset   0004EFF3 (323571)
│ │ │ │ -9EBC4 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EBC4: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EBDF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EBE1   Length              0005 (5)
│ │ │ │ -9EBE3   Flags               01 (1) 'Modification'
│ │ │ │ -9EBE4   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EBE8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EBEA   Length              000B (11)
│ │ │ │ -9EBEC   Version             01 (1)
│ │ │ │ -9EBED   UID Size            04 (4)
│ │ │ │ -9EBEE   UID                 00000000 (0)
│ │ │ │ -9EBF2   GID Size            04 (4)
│ │ │ │ -9EBF3   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EBF7 CENTRAL HEADER #46    02014B50 (33639248)
│ │ │ │ -9EBFB Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EBFC Created OS            03 (3) 'Unix'
│ │ │ │ -9EBFD Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EBFE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EBFF General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EC01 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EC03 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EC07 CRC                   2A5112D6 (709956310)
│ │ │ │ -9EC0B Compressed Size       000016F1 (5873)
│ │ │ │ -9EC0F Uncompressed Size     00007A6D (31341)
│ │ │ │ -9EC13 Filename Length       001F (31)
│ │ │ │ -9EC15 Extra Length          0018 (24)
│ │ │ │ -9EC17 Comment Length        0000 (0)
│ │ │ │ -9EC19 Disk Start            0000 (0)
│ │ │ │ -9EC1B Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EC1D Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EC21 Local Header Offset   0004F4B0 (324784)
│ │ │ │ -9EC25 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EC25: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EC44 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EC46   Length              0005 (5)
│ │ │ │ -9EC48   Flags               01 (1) 'Modification'
│ │ │ │ -9EC49   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EC4D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EC4F   Length              000B (11)
│ │ │ │ -9EC51   Version             01 (1)
│ │ │ │ -9EC52   UID Size            04 (4)
│ │ │ │ -9EC53   UID                 00000000 (0)
│ │ │ │ -9EC57   GID Size            04 (4)
│ │ │ │ -9EC58   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EC5C CENTRAL HEADER #47    02014B50 (33639248)
│ │ │ │ -9EC60 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EC61 Created OS            03 (3) 'Unix'
│ │ │ │ -9EC62 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EC63 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EC64 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EC66 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EC68 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EC6C CRC                   1BA8E4E8 (464053480)
│ │ │ │ -9EC70 Compressed Size       0000416A (16746)
│ │ │ │ -9EC74 Uncompressed Size     0001CF93 (118675)
│ │ │ │ -9EC78 Filename Length       0010 (16)
│ │ │ │ -9EC7A Extra Length          0018 (24)
│ │ │ │ -9EC7C Comment Length        0000 (0)
│ │ │ │ -9EC7E Disk Start            0000 (0)
│ │ │ │ -9EC80 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EC82 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EC86 Local Header Offset   00050BFA (330746)
│ │ │ │ -9EC8A Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EC8A: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EC9A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EC9C   Length              0005 (5)
│ │ │ │ -9EC9E   Flags               01 (1) 'Modification'
│ │ │ │ -9EC9F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9ECA3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9ECA5   Length              000B (11)
│ │ │ │ -9ECA7   Version             01 (1)
│ │ │ │ -9ECA8   UID Size            04 (4)
│ │ │ │ -9ECA9   UID                 00000000 (0)
│ │ │ │ -9ECAD   GID Size            04 (4)
│ │ │ │ -9ECAE   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9ECB2 CENTRAL HEADER #48    02014B50 (33639248)
│ │ │ │ -9ECB6 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9ECB7 Created OS            03 (3) 'Unix'
│ │ │ │ -9ECB8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9ECB9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9ECBA General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9ECBC Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9ECBE Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9ECC2 CRC                   2020DAF6 (539024118)
│ │ │ │ -9ECC6 Compressed Size       00000A94 (2708)
│ │ │ │ -9ECCA Uncompressed Size     00002105 (8453)
│ │ │ │ -9ECCE Filename Length       0014 (20)
│ │ │ │ -9ECD0 Extra Length          0018 (24)
│ │ │ │ -9ECD2 Comment Length        0000 (0)
│ │ │ │ -9ECD4 Disk Start            0000 (0)
│ │ │ │ -9ECD6 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9ECD8 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9ECDC Local Header Offset   00054DAE (347566)
│ │ │ │ -9ECE0 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9ECE0: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9ECF4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9ECF6   Length              0005 (5)
│ │ │ │ -9ECF8   Flags               01 (1) 'Modification'
│ │ │ │ -9ECF9   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9ECFD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9ECFF   Length              000B (11)
│ │ │ │ -9ED01   Version             01 (1)
│ │ │ │ -9ED02   UID Size            04 (4)
│ │ │ │ -9ED03   UID                 00000000 (0)
│ │ │ │ -9ED07   GID Size            04 (4)
│ │ │ │ -9ED08   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9ED0C CENTRAL HEADER #49    02014B50 (33639248)
│ │ │ │ -9ED10 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9ED11 Created OS            03 (3) 'Unix'
│ │ │ │ -9ED12 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9ED13 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9ED14 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9ED16 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9ED18 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9ED1C CRC                   F1FD1FA8 (4059897768)
│ │ │ │ -9ED20 Compressed Size       0000AC9D (44189)
│ │ │ │ -9ED24 Uncompressed Size     0003E418 (255000)
│ │ │ │ -9ED28 Filename Length       0017 (23)
│ │ │ │ -9ED2A Extra Length          0018 (24)
│ │ │ │ -9ED2C Comment Length        0000 (0)
│ │ │ │ -9ED2E Disk Start            0000 (0)
│ │ │ │ -9ED30 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9ED32 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9ED36 Local Header Offset   00055890 (350352)
│ │ │ │ -9ED3A Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9ED3A: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9ED51 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9ED53   Length              0005 (5)
│ │ │ │ -9ED55   Flags               01 (1) 'Modification'
│ │ │ │ -9ED56   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9ED5A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9ED5C   Length              000B (11)
│ │ │ │ -9ED5E   Version             01 (1)
│ │ │ │ -9ED5F   UID Size            04 (4)
│ │ │ │ -9ED60   UID                 00000000 (0)
│ │ │ │ -9ED64   GID Size            04 (4)
│ │ │ │ -9ED65   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9ED69 CENTRAL HEADER #50    02014B50 (33639248)
│ │ │ │ -9ED6D Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9ED6E Created OS            03 (3) 'Unix'
│ │ │ │ -9ED6F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9ED70 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9ED71 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9ED73 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9ED75 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9ED79 CRC                   97230023 (2535653411)
│ │ │ │ -9ED7D Compressed Size       00000401 (1025)
│ │ │ │ -9ED81 Uncompressed Size     0000093D (2365)
│ │ │ │ -9ED85 Filename Length       0013 (19)
│ │ │ │ -9ED87 Extra Length          0018 (24)
│ │ │ │ -9ED89 Comment Length        0000 (0)
│ │ │ │ -9ED8B Disk Start            0000 (0)
│ │ │ │ -9ED8D Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9ED8F Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9ED93 Local Header Offset   0006057E (394622)
│ │ │ │ -9ED97 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9ED97: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EDAA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EDAC   Length              0005 (5)
│ │ │ │ -9EDAE   Flags               01 (1) 'Modification'
│ │ │ │ -9EDAF   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EDB3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EDB5   Length              000B (11)
│ │ │ │ -9EDB7   Version             01 (1)
│ │ │ │ -9EDB8   UID Size            04 (4)
│ │ │ │ -9EDB9   UID                 00000000 (0)
│ │ │ │ -9EDBD   GID Size            04 (4)
│ │ │ │ -9EDBE   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EDC2 CENTRAL HEADER #51    02014B50 (33639248)
│ │ │ │ -9EDC6 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EDC7 Created OS            03 (3) 'Unix'
│ │ │ │ -9EDC8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EDC9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EDCA General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EDCC Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EDCE Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EDD2 CRC                   15AD4D8E (363679118)
│ │ │ │ -9EDD6 Compressed Size       000014DB (5339)
│ │ │ │ -9EDDA Uncompressed Size     0000687B (26747)
│ │ │ │ -9EDDE Filename Length       0012 (18)
│ │ │ │ -9EDE0 Extra Length          0018 (24)
│ │ │ │ -9EDE2 Comment Length        0000 (0)
│ │ │ │ -9EDE4 Disk Start            0000 (0)
│ │ │ │ -9EDE6 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EDE8 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EDEC Local Header Offset   000609CC (395724)
│ │ │ │ -9EDF0 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EDF0: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EE02 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EE04   Length              0005 (5)
│ │ │ │ -9EE06   Flags               01 (1) 'Modification'
│ │ │ │ -9EE07   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EE0B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EE0D   Length              000B (11)
│ │ │ │ -9EE0F   Version             01 (1)
│ │ │ │ -9EE10   UID Size            04 (4)
│ │ │ │ -9EE11   UID                 00000000 (0)
│ │ │ │ -9EE15   GID Size            04 (4)
│ │ │ │ -9EE16   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EE1A CENTRAL HEADER #52    02014B50 (33639248)
│ │ │ │ -9EE1E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EE1F Created OS            03 (3) 'Unix'
│ │ │ │ -9EE20 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EE21 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EE22 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EE24 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EE26 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EE2A CRC                   BDF3884F (3186853967)
│ │ │ │ -9EE2E Compressed Size       000011EB (4587)
│ │ │ │ -9EE32 Uncompressed Size     000040F5 (16629)
│ │ │ │ -9EE36 Filename Length       0012 (18)
│ │ │ │ -9EE38 Extra Length          0018 (24)
│ │ │ │ -9EE3A Comment Length        0000 (0)
│ │ │ │ -9EE3C Disk Start            0000 (0)
│ │ │ │ -9EE3E Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EE40 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EE44 Local Header Offset   00061EF3 (401139)
│ │ │ │ -9EE48 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EE48: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EE5A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EE5C   Length              0005 (5)
│ │ │ │ -9EE5E   Flags               01 (1) 'Modification'
│ │ │ │ -9EE5F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EE63 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EE65   Length              000B (11)
│ │ │ │ -9EE67   Version             01 (1)
│ │ │ │ -9EE68   UID Size            04 (4)
│ │ │ │ -9EE69   UID                 00000000 (0)
│ │ │ │ -9EE6D   GID Size            04 (4)
│ │ │ │ -9EE6E   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EE72 CENTRAL HEADER #53    02014B50 (33639248)
│ │ │ │ -9EE76 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EE77 Created OS            03 (3) 'Unix'
│ │ │ │ -9EE78 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EE79 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EE7A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EE7C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EE7E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EE82 CRC                   2C7ABAF2 (746240754)
│ │ │ │ -9EE86 Compressed Size       000009DA (2522)
│ │ │ │ -9EE8A Uncompressed Size     00003529 (13609)
│ │ │ │ -9EE8E Filename Length       0019 (25)
│ │ │ │ -9EE90 Extra Length          0018 (24)
│ │ │ │ -9EE92 Comment Length        0000 (0)
│ │ │ │ -9EE94 Disk Start            0000 (0)
│ │ │ │ -9EE96 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EE98 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EE9C Local Header Offset   0006312A (405802)
│ │ │ │ -9EEA0 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EEA0: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EEB9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EEBB   Length              0005 (5)
│ │ │ │ -9EEBD   Flags               01 (1) 'Modification'
│ │ │ │ -9EEBE   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EEC2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EEC4   Length              000B (11)
│ │ │ │ -9EEC6   Version             01 (1)
│ │ │ │ -9EEC7   UID Size            04 (4)
│ │ │ │ -9EEC8   UID                 00000000 (0)
│ │ │ │ -9EECC   GID Size            04 (4)
│ │ │ │ -9EECD   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EED1 CENTRAL HEADER #54    02014B50 (33639248)
│ │ │ │ -9EED5 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EED6 Created OS            03 (3) 'Unix'
│ │ │ │ -9EED7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EED8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EED9 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EEDB Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EEDD Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EEE1 CRC                   D69E8D28 (3600715048)
│ │ │ │ -9EEE5 Compressed Size       000018B1 (6321)
│ │ │ │ -9EEE9 Uncompressed Size     0000A605 (42501)
│ │ │ │ -9EEED Filename Length       0019 (25)
│ │ │ │ -9EEEF Extra Length          0018 (24)
│ │ │ │ -9EEF1 Comment Length        0000 (0)
│ │ │ │ -9EEF3 Disk Start            0000 (0)
│ │ │ │ -9EEF5 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EEF7 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EEFB Local Header Offset   00063B57 (408407)
│ │ │ │ -9EEFF Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EEFF: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EF18 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EF1A   Length              0005 (5)
│ │ │ │ -9EF1C   Flags               01 (1) 'Modification'
│ │ │ │ -9EF1D   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EF21 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EF23   Length              000B (11)
│ │ │ │ -9EF25   Version             01 (1)
│ │ │ │ -9EF26   UID Size            04 (4)
│ │ │ │ -9EF27   UID                 00000000 (0)
│ │ │ │ -9EF2B   GID Size            04 (4)
│ │ │ │ -9EF2C   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EF30 CENTRAL HEADER #55    02014B50 (33639248)
│ │ │ │ -9EF34 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EF35 Created OS            03 (3) 'Unix'
│ │ │ │ -9EF36 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EF37 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EF38 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EF3A Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EF3C Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EF40 CRC                   47E0D6DC (1205917404)
│ │ │ │ -9EF44 Compressed Size       0000177E (6014)
│ │ │ │ -9EF48 Uncompressed Size     0000472C (18220)
│ │ │ │ -9EF4C Filename Length       0014 (20)
│ │ │ │ -9EF4E Extra Length          0018 (24)
│ │ │ │ -9EF50 Comment Length        0000 (0)
│ │ │ │ -9EF52 Disk Start            0000 (0)
│ │ │ │ -9EF54 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EF56 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EF5A Local Header Offset   0006545B (414811)
│ │ │ │ -9EF5E Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EF5E: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EF72 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EF74   Length              0005 (5)
│ │ │ │ -9EF76   Flags               01 (1) 'Modification'
│ │ │ │ -9EF77   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EF7B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EF7D   Length              000B (11)
│ │ │ │ -9EF7F   Version             01 (1)
│ │ │ │ -9EF80   UID Size            04 (4)
│ │ │ │ -9EF81   UID                 00000000 (0)
│ │ │ │ -9EF85   GID Size            04 (4)
│ │ │ │ -9EF86   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EF8A CENTRAL HEADER #56    02014B50 (33639248)
│ │ │ │ -9EF8E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EF8F Created OS            03 (3) 'Unix'
│ │ │ │ -9EF90 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EF91 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EF92 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EF94 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EF96 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EF9A CRC                   EDF51269 (3992261225)
│ │ │ │ -9EF9E Compressed Size       0000040B (1035)
│ │ │ │ -9EFA2 Uncompressed Size     00000825 (2085)
│ │ │ │ -9EFA6 Filename Length       001C (28)
│ │ │ │ -9EFA8 Extra Length          0018 (24)
│ │ │ │ -9EFAA Comment Length        0000 (0)
│ │ │ │ -9EFAC Disk Start            0000 (0)
│ │ │ │ -9EFAE Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9EFB0 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9EFB4 Local Header Offset   00066C27 (420903)
│ │ │ │ -9EFB8 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9EFB8: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9EFD4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9EFD6   Length              0005 (5)
│ │ │ │ -9EFD8   Flags               01 (1) 'Modification'
│ │ │ │ -9EFD9   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9EFDD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9EFDF   Length              000B (11)
│ │ │ │ -9EFE1   Version             01 (1)
│ │ │ │ -9EFE2   UID Size            04 (4)
│ │ │ │ -9EFE3   UID                 00000000 (0)
│ │ │ │ -9EFE7   GID Size            04 (4)
│ │ │ │ -9EFE8   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9EFEC CENTRAL HEADER #57    02014B50 (33639248)
│ │ │ │ -9EFF0 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9EFF1 Created OS            03 (3) 'Unix'
│ │ │ │ -9EFF2 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9EFF3 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9EFF4 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9EFF6 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9EFF8 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9EFFC CRC                   AC935B99 (2895338393)
│ │ │ │ -9F000 Compressed Size       00002483 (9347)
│ │ │ │ -9F004 Uncompressed Size     0000B56F (46447)
│ │ │ │ -9F008 Filename Length       001F (31)
│ │ │ │ -9F00A Extra Length          0018 (24)
│ │ │ │ -9F00C Comment Length        0000 (0)
│ │ │ │ -9F00E Disk Start            0000 (0)
│ │ │ │ -9F010 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F012 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F016 Local Header Offset   00067088 (422024)
│ │ │ │ -9F01A Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F01A: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F039 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F03B   Length              0005 (5)
│ │ │ │ -9F03D   Flags               01 (1) 'Modification'
│ │ │ │ -9F03E   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F042 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F044   Length              000B (11)
│ │ │ │ -9F046   Version             01 (1)
│ │ │ │ -9F047   UID Size            04 (4)
│ │ │ │ -9F048   UID                 00000000 (0)
│ │ │ │ -9F04C   GID Size            04 (4)
│ │ │ │ -9F04D   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F051 CENTRAL HEADER #58    02014B50 (33639248)
│ │ │ │ -9F055 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F056 Created OS            03 (3) 'Unix'
│ │ │ │ -9F057 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F058 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F059 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F05B Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F05D Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F061 CRC                   EE677FF5 (3999760373)
│ │ │ │ -9F065 Compressed Size       00000E81 (3713)
│ │ │ │ -9F069 Uncompressed Size     000052D9 (21209)
│ │ │ │ -9F06D Filename Length       001F (31)
│ │ │ │ -9F06F Extra Length          0018 (24)
│ │ │ │ -9F071 Comment Length        0000 (0)
│ │ │ │ -9F073 Disk Start            0000 (0)
│ │ │ │ -9F075 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F077 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F07B Local Header Offset   00069564 (431460)
│ │ │ │ -9F07F Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F07F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F09E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F0A0   Length              0005 (5)
│ │ │ │ -9F0A2   Flags               01 (1) 'Modification'
│ │ │ │ -9F0A3   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F0A7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F0A9   Length              000B (11)
│ │ │ │ -9F0AB   Version             01 (1)
│ │ │ │ -9F0AC   UID Size            04 (4)
│ │ │ │ -9F0AD   UID                 00000000 (0)
│ │ │ │ -9F0B1   GID Size            04 (4)
│ │ │ │ -9F0B2   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F0B6 CENTRAL HEADER #59    02014B50 (33639248)
│ │ │ │ -9F0BA Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F0BB Created OS            03 (3) 'Unix'
│ │ │ │ -9F0BC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F0BD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F0BE General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F0C0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F0C2 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F0C6 CRC                   651C981F (1696372767)
│ │ │ │ -9F0CA Compressed Size       00000A43 (2627)
│ │ │ │ -9F0CE Uncompressed Size     0000247A (9338)
│ │ │ │ -9F0D2 Filename Length       0013 (19)
│ │ │ │ -9F0D4 Extra Length          0018 (24)
│ │ │ │ -9F0D6 Comment Length        0000 (0)
│ │ │ │ -9F0D8 Disk Start            0000 (0)
│ │ │ │ -9F0DA Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F0DC Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F0E0 Local Header Offset   0006A43E (435262)
│ │ │ │ -9F0E4 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F0E4: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F0F7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F0F9   Length              0005 (5)
│ │ │ │ -9F0FB   Flags               01 (1) 'Modification'
│ │ │ │ -9F0FC   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F100 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F102   Length              000B (11)
│ │ │ │ -9F104   Version             01 (1)
│ │ │ │ -9F105   UID Size            04 (4)
│ │ │ │ -9F106   UID                 00000000 (0)
│ │ │ │ -9F10A   GID Size            04 (4)
│ │ │ │ -9F10B   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F10F CENTRAL HEADER #60    02014B50 (33639248)
│ │ │ │ -9F113 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F114 Created OS            03 (3) 'Unix'
│ │ │ │ -9F115 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F116 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F117 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F119 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F11B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F11F CRC                   6A1CF0DA (1780281562)
│ │ │ │ -9F123 Compressed Size       00002486 (9350)
│ │ │ │ -9F127 Uncompressed Size     0000B84C (47180)
│ │ │ │ -9F12B Filename Length       0019 (25)
│ │ │ │ -9F12D Extra Length          0018 (24)
│ │ │ │ -9F12F Comment Length        0000 (0)
│ │ │ │ -9F131 Disk Start            0000 (0)
│ │ │ │ -9F133 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F135 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F139 Local Header Offset   0006AECE (437966)
│ │ │ │ -9F13D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F13D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F156 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F158   Length              0005 (5)
│ │ │ │ -9F15A   Flags               01 (1) 'Modification'
│ │ │ │ -9F15B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F15F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F161   Length              000B (11)
│ │ │ │ -9F163   Version             01 (1)
│ │ │ │ -9F164   UID Size            04 (4)
│ │ │ │ -9F165   UID                 00000000 (0)
│ │ │ │ -9F169   GID Size            04 (4)
│ │ │ │ -9F16A   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F16E CENTRAL HEADER #61    02014B50 (33639248)
│ │ │ │ -9F172 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F173 Created OS            03 (3) 'Unix'
│ │ │ │ -9F174 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F175 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F176 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F178 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F17A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F17E CRC                   E9583C9A (3914874010)
│ │ │ │ -9F182 Compressed Size       00000EF9 (3833)
│ │ │ │ -9F186 Uncompressed Size     00003A2C (14892)
│ │ │ │ -9F18A Filename Length       0024 (36)
│ │ │ │ -9F18C Extra Length          0018 (24)
│ │ │ │ -9F18E Comment Length        0000 (0)
│ │ │ │ -9F190 Disk Start            0000 (0)
│ │ │ │ -9F192 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F194 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F198 Local Header Offset   0006D3A7 (447399)
│ │ │ │ -9F19C Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F19C: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F1C0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F1C2   Length              0005 (5)
│ │ │ │ -9F1C4   Flags               01 (1) 'Modification'
│ │ │ │ -9F1C5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F1C9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F1CB   Length              000B (11)
│ │ │ │ -9F1CD   Version             01 (1)
│ │ │ │ -9F1CE   UID Size            04 (4)
│ │ │ │ -9F1CF   UID                 00000000 (0)
│ │ │ │ -9F1D3   GID Size            04 (4)
│ │ │ │ -9F1D4   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F1D8 CENTRAL HEADER #62    02014B50 (33639248)
│ │ │ │ -9F1DC Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F1DD Created OS            03 (3) 'Unix'
│ │ │ │ -9F1DE Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F1DF Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F1E0 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F1E2 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F1E4 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F1E8 CRC                   0D165AC6 (219568838)
│ │ │ │ -9F1EC Compressed Size       00001AC1 (6849)
│ │ │ │ -9F1F0 Uncompressed Size     00005EDC (24284)
│ │ │ │ -9F1F4 Filename Length       0017 (23)
│ │ │ │ -9F1F6 Extra Length          0018 (24)
│ │ │ │ -9F1F8 Comment Length        0000 (0)
│ │ │ │ -9F1FA Disk Start            0000 (0)
│ │ │ │ -9F1FC Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F1FE Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F202 Local Header Offset   0006E2FE (451326)
│ │ │ │ -9F206 Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F206: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F21D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F21F   Length              0005 (5)
│ │ │ │ -9F221   Flags               01 (1) 'Modification'
│ │ │ │ -9F222   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F226 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F228   Length              000B (11)
│ │ │ │ -9F22A   Version             01 (1)
│ │ │ │ -9F22B   UID Size            04 (4)
│ │ │ │ -9F22C   UID                 00000000 (0)
│ │ │ │ -9F230   GID Size            04 (4)
│ │ │ │ -9F231   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F235 CENTRAL HEADER #63    02014B50 (33639248)
│ │ │ │ -9F239 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F23A Created OS            03 (3) 'Unix'
│ │ │ │ -9F23B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F23C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F23D General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F23F Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F241 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F245 CRC                   11E32AF1 (300100337)
│ │ │ │ -9F249 Compressed Size       00000ED3 (3795)
│ │ │ │ -9F24D Uncompressed Size     000038E2 (14562)
│ │ │ │ -9F251 Filename Length       0023 (35)
│ │ │ │ -9F253 Extra Length          0018 (24)
│ │ │ │ -9F255 Comment Length        0000 (0)
│ │ │ │ -9F257 Disk Start            0000 (0)
│ │ │ │ -9F259 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F25B Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F25F Local Header Offset   0006FE10 (458256)
│ │ │ │ -9F263 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F263: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F286 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F288   Length              0005 (5)
│ │ │ │ -9F28A   Flags               01 (1) 'Modification'
│ │ │ │ -9F28B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F28F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F291   Length              000B (11)
│ │ │ │ -9F293   Version             01 (1)
│ │ │ │ -9F294   UID Size            04 (4)
│ │ │ │ -9F295   UID                 00000000 (0)
│ │ │ │ -9F299   GID Size            04 (4)
│ │ │ │ -9F29A   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F29E CENTRAL HEADER #64    02014B50 (33639248)
│ │ │ │ -9F2A2 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F2A3 Created OS            03 (3) 'Unix'
│ │ │ │ -9F2A4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F2A5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F2A6 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F2A8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F2AA Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F2AE CRC                   2DB7929F (767005343)
│ │ │ │ -9F2B2 Compressed Size       00000113 (275)
│ │ │ │ -9F2B6 Uncompressed Size     000001F3 (499)
│ │ │ │ -9F2BA Filename Length       001B (27)
│ │ │ │ -9F2BC Extra Length          0018 (24)
│ │ │ │ -9F2BE Comment Length        0000 (0)
│ │ │ │ -9F2C0 Disk Start            0000 (0)
│ │ │ │ -9F2C2 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F2C4 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F2C8 Local Header Offset   00070D40 (462144)
│ │ │ │ -9F2CC Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F2CC: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F2E7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F2E9   Length              0005 (5)
│ │ │ │ -9F2EB   Flags               01 (1) 'Modification'
│ │ │ │ -9F2EC   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F2F0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F2F2   Length              000B (11)
│ │ │ │ -9F2F4   Version             01 (1)
│ │ │ │ -9F2F5   UID Size            04 (4)
│ │ │ │ -9F2F6   UID                 00000000 (0)
│ │ │ │ -9F2FA   GID Size            04 (4)
│ │ │ │ -9F2FB   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F2FF CENTRAL HEADER #65    02014B50 (33639248)
│ │ │ │ -9F303 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F304 Created OS            03 (3) 'Unix'
│ │ │ │ -9F305 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F306 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F307 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F309 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F30B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F30F CRC                   BC4620C3 (3158712515)
│ │ │ │ -9F313 Compressed Size       00001892 (6290)
│ │ │ │ -9F317 Uncompressed Size     00008FAC (36780)
│ │ │ │ -9F31B Filename Length       001D (29)
│ │ │ │ -9F31D Extra Length          0018 (24)
│ │ │ │ -9F31F Comment Length        0000 (0)
│ │ │ │ -9F321 Disk Start            0000 (0)
│ │ │ │ -9F323 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F325 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F329 Local Header Offset   00070EA8 (462504)
│ │ │ │ -9F32D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F32D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F34A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F34C   Length              0005 (5)
│ │ │ │ -9F34E   Flags               01 (1) 'Modification'
│ │ │ │ -9F34F   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F353 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F355   Length              000B (11)
│ │ │ │ -9F357   Version             01 (1)
│ │ │ │ -9F358   UID Size            04 (4)
│ │ │ │ -9F359   UID                 00000000 (0)
│ │ │ │ -9F35D   GID Size            04 (4)
│ │ │ │ -9F35E   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F362 CENTRAL HEADER #66    02014B50 (33639248)
│ │ │ │ -9F366 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F367 Created OS            03 (3) 'Unix'
│ │ │ │ -9F368 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F369 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F36A General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F36C Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F36E Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F372 CRC                   63FED801 (1677645825)
│ │ │ │ -9F376 Compressed Size       0000164D (5709)
│ │ │ │ -9F37A Uncompressed Size     00003A9B (15003)
│ │ │ │ -9F37E Filename Length       0015 (21)
│ │ │ │ -9F380 Extra Length          0018 (24)
│ │ │ │ -9F382 Comment Length        0000 (0)
│ │ │ │ -9F384 Disk Start            0000 (0)
│ │ │ │ -9F386 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F388 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F38C Local Header Offset   00072791 (468881)
│ │ │ │ -9F390 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F390: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F3A5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F3A7   Length              0005 (5)
│ │ │ │ -9F3A9   Flags               01 (1) 'Modification'
│ │ │ │ -9F3AA   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F3AE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F3B0   Length              000B (11)
│ │ │ │ -9F3B2   Version             01 (1)
│ │ │ │ -9F3B3   UID Size            04 (4)
│ │ │ │ -9F3B4   UID                 00000000 (0)
│ │ │ │ -9F3B8   GID Size            04 (4)
│ │ │ │ -9F3B9   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F3BD CENTRAL HEADER #67    02014B50 (33639248)
│ │ │ │ -9F3C1 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F3C2 Created OS            03 (3) 'Unix'
│ │ │ │ -9F3C3 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F3C4 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F3C5 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F3C7 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F3C9 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F3CD CRC                   ADE907F6 (2917730294)
│ │ │ │ -9F3D1 Compressed Size       00003B50 (15184)
│ │ │ │ -9F3D5 Uncompressed Size     0001185B (71771)
│ │ │ │ -9F3D9 Filename Length       0016 (22)
│ │ │ │ -9F3DB Extra Length          0018 (24)
│ │ │ │ -9F3DD Comment Length        0000 (0)
│ │ │ │ -9F3DF Disk Start            0000 (0)
│ │ │ │ -9F3E1 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F3E3 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F3E7 Local Header Offset   00073E2D (474669)
│ │ │ │ -9F3EB Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F3EB: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F401 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F403   Length              0005 (5)
│ │ │ │ -9F405   Flags               01 (1) 'Modification'
│ │ │ │ -9F406   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F40A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F40C   Length              000B (11)
│ │ │ │ -9F40E   Version             01 (1)
│ │ │ │ -9F40F   UID Size            04 (4)
│ │ │ │ -9F410   UID                 00000000 (0)
│ │ │ │ -9F414   GID Size            04 (4)
│ │ │ │ -9F415   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F419 CENTRAL HEADER #68    02014B50 (33639248)
│ │ │ │ -9F41D Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F41E Created OS            03 (3) 'Unix'
│ │ │ │ -9F41F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F420 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F421 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F423 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F425 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F429 CRC                   7DF00FFC (2112884732)
│ │ │ │ -9F42D Compressed Size       00003E85 (16005)
│ │ │ │ -9F431 Uncompressed Size     0001C17B (115067)
│ │ │ │ -9F435 Filename Length       0019 (25)
│ │ │ │ -9F437 Extra Length          0018 (24)
│ │ │ │ -9F439 Comment Length        0000 (0)
│ │ │ │ -9F43B Disk Start            0000 (0)
│ │ │ │ -9F43D Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F43F Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F443 Local Header Offset   000779CD (489933)
│ │ │ │ -9F447 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F447: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F460 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F462   Length              0005 (5)
│ │ │ │ -9F464   Flags               01 (1) 'Modification'
│ │ │ │ -9F465   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F469 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F46B   Length              000B (11)
│ │ │ │ -9F46D   Version             01 (1)
│ │ │ │ -9F46E   UID Size            04 (4)
│ │ │ │ -9F46F   UID                 00000000 (0)
│ │ │ │ -9F473   GID Size            04 (4)
│ │ │ │ -9F474   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F478 CENTRAL HEADER #69    02014B50 (33639248)
│ │ │ │ -9F47C Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F47D Created OS            03 (3) 'Unix'
│ │ │ │ -9F47E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F47F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F480 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F482 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F484 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F488 CRC                   08716215 (141648405)
│ │ │ │ -9F48C Compressed Size       00000833 (2099)
│ │ │ │ -9F490 Uncompressed Size     00003383 (13187)
│ │ │ │ -9F494 Filename Length       0011 (17)
│ │ │ │ -9F496 Extra Length          0018 (24)
│ │ │ │ -9F498 Comment Length        0000 (0)
│ │ │ │ -9F49A Disk Start            0000 (0)
│ │ │ │ -9F49C Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F49E Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F4A2 Local Header Offset   0007B8A5 (506021)
│ │ │ │ -9F4A6 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F4A6: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F4B7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F4B9   Length              0005 (5)
│ │ │ │ -9F4BB   Flags               01 (1) 'Modification'
│ │ │ │ -9F4BC   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F4C0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F4C2   Length              000B (11)
│ │ │ │ -9F4C4   Version             01 (1)
│ │ │ │ -9F4C5   UID Size            04 (4)
│ │ │ │ -9F4C6   UID                 00000000 (0)
│ │ │ │ -9F4CA   GID Size            04 (4)
│ │ │ │ -9F4CB   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F4CF CENTRAL HEADER #70    02014B50 (33639248)
│ │ │ │ -9F4D3 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F4D4 Created OS            03 (3) 'Unix'
│ │ │ │ -9F4D5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F4D6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F4D7 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F4D9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F4DB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F4DF CRC                   9B8ACD82 (2609565058)
│ │ │ │ -9F4E3 Compressed Size       00005188 (20872)
│ │ │ │ -9F4E7 Uncompressed Size     0001FB6C (129900)
│ │ │ │ -9F4EB Filename Length       0015 (21)
│ │ │ │ -9F4ED Extra Length          0018 (24)
│ │ │ │ -9F4EF Comment Length        0000 (0)
│ │ │ │ -9F4F1 Disk Start            0000 (0)
│ │ │ │ -9F4F3 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F4F5 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F4F9 Local Header Offset   0007C123 (508195)
│ │ │ │ -9F4FD Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F4FD: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F512 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F514   Length              0005 (5)
│ │ │ │ -9F516   Flags               01 (1) 'Modification'
│ │ │ │ -9F517   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F51B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F51D   Length              000B (11)
│ │ │ │ -9F51F   Version             01 (1)
│ │ │ │ -9F520   UID Size            04 (4)
│ │ │ │ -9F521   UID                 00000000 (0)
│ │ │ │ -9F525   GID Size            04 (4)
│ │ │ │ -9F526   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F52A CENTRAL HEADER #71    02014B50 (33639248)
│ │ │ │ -9F52E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F52F Created OS            03 (3) 'Unix'
│ │ │ │ -9F530 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F531 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F532 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F534 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F536 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F53A CRC                   535E57D6 (1398691798)
│ │ │ │ -9F53E Compressed Size       00001B05 (6917)
│ │ │ │ -9F542 Uncompressed Size     000081CF (33231)
│ │ │ │ -9F546 Filename Length       0019 (25)
│ │ │ │ -9F548 Extra Length          0018 (24)
│ │ │ │ -9F54A Comment Length        0000 (0)
│ │ │ │ -9F54C Disk Start            0000 (0)
│ │ │ │ -9F54E Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F550 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F554 Local Header Offset   000812FA (529146)
│ │ │ │ -9F558 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F558: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F571 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F573   Length              0005 (5)
│ │ │ │ -9F575   Flags               01 (1) 'Modification'
│ │ │ │ -9F576   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F57A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F57C   Length              000B (11)
│ │ │ │ -9F57E   Version             01 (1)
│ │ │ │ -9F57F   UID Size            04 (4)
│ │ │ │ -9F580   UID                 00000000 (0)
│ │ │ │ -9F584   GID Size            04 (4)
│ │ │ │ -9F585   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F589 CENTRAL HEADER #72    02014B50 (33639248)
│ │ │ │ -9F58D Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F58E Created OS            03 (3) 'Unix'
│ │ │ │ -9F58F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F590 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F591 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F593 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F595 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F599 CRC                   02D5C73B (47564603)
│ │ │ │ -9F59D Compressed Size       00000D96 (3478)
│ │ │ │ -9F5A1 Uncompressed Size     00002E9F (11935)
│ │ │ │ -9F5A5 Filename Length       0018 (24)
│ │ │ │ -9F5A7 Extra Length          0018 (24)
│ │ │ │ -9F5A9 Comment Length        0000 (0)
│ │ │ │ -9F5AB Disk Start            0000 (0)
│ │ │ │ -9F5AD Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F5AF Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F5B3 Local Header Offset   00082E52 (536146)
│ │ │ │ -9F5B7 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F5B7: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F5CF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F5D1   Length              0005 (5)
│ │ │ │ -9F5D3   Flags               01 (1) 'Modification'
│ │ │ │ -9F5D4   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F5D8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F5DA   Length              000B (11)
│ │ │ │ -9F5DC   Version             01 (1)
│ │ │ │ -9F5DD   UID Size            04 (4)
│ │ │ │ -9F5DE   UID                 00000000 (0)
│ │ │ │ -9F5E2   GID Size            04 (4)
│ │ │ │ -9F5E3   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F5E7 CENTRAL HEADER #73    02014B50 (33639248)
│ │ │ │ -9F5EB Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F5EC Created OS            03 (3) 'Unix'
│ │ │ │ -9F5ED Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F5EE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F5EF General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F5F1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F5F3 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F5F7 CRC                   B429472D (3022604077)
│ │ │ │ -9F5FB Compressed Size       000001E1 (481)
│ │ │ │ -9F5FF Uncompressed Size     00000323 (803)
│ │ │ │ -9F603 Filename Length       0011 (17)
│ │ │ │ -9F605 Extra Length          0018 (24)
│ │ │ │ -9F607 Comment Length        0000 (0)
│ │ │ │ -9F609 Disk Start            0000 (0)
│ │ │ │ -9F60B Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F60D Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F611 Local Header Offset   00083C3A (539706)
│ │ │ │ -9F615 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F615: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F626 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F628   Length              0005 (5)
│ │ │ │ -9F62A   Flags               01 (1) 'Modification'
│ │ │ │ -9F62B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F62F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F631   Length              000B (11)
│ │ │ │ -9F633   Version             01 (1)
│ │ │ │ -9F634   UID Size            04 (4)
│ │ │ │ -9F635   UID                 00000000 (0)
│ │ │ │ -9F639   GID Size            04 (4)
│ │ │ │ -9F63A   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F63E CENTRAL HEADER #74    02014B50 (33639248)
│ │ │ │ -9F642 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F643 Created OS            03 (3) 'Unix'
│ │ │ │ -9F644 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F645 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F646 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F648 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F64A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F64E CRC                   1E45F0E3 (507900131)
│ │ │ │ -9F652 Compressed Size       000006C1 (1729)
│ │ │ │ -9F656 Uncompressed Size     00001439 (5177)
│ │ │ │ -9F65A Filename Length       0019 (25)
│ │ │ │ -9F65C Extra Length          0018 (24)
│ │ │ │ -9F65E Comment Length        0000 (0)
│ │ │ │ -9F660 Disk Start            0000 (0)
│ │ │ │ -9F662 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F664 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F668 Local Header Offset   00083E66 (540262)
│ │ │ │ -9F66C Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F66C: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F685 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F687   Length              0005 (5)
│ │ │ │ -9F689   Flags               01 (1) 'Modification'
│ │ │ │ -9F68A   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F68E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F690   Length              000B (11)
│ │ │ │ -9F692   Version             01 (1)
│ │ │ │ -9F693   UID Size            04 (4)
│ │ │ │ -9F694   UID                 00000000 (0)
│ │ │ │ -9F698   GID Size            04 (4)
│ │ │ │ -9F699   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F69D CENTRAL HEADER #75    02014B50 (33639248)
│ │ │ │ -9F6A1 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F6A2 Created OS            03 (3) 'Unix'
│ │ │ │ -9F6A3 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F6A4 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F6A5 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F6A7 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F6A9 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F6AD CRC                   31106466 (823157862)
│ │ │ │ -9F6B1 Compressed Size       00001B86 (7046)
│ │ │ │ -9F6B5 Uncompressed Size     00009F03 (40707)
│ │ │ │ -9F6B9 Filename Length       0018 (24)
│ │ │ │ -9F6BB Extra Length          0018 (24)
│ │ │ │ -9F6BD Comment Length        0000 (0)
│ │ │ │ -9F6BF Disk Start            0000 (0)
│ │ │ │ -9F6C1 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F6C3 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F6C7 Local Header Offset   0008457A (542074)
│ │ │ │ -9F6CB Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F6CB: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F6E3 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F6E5   Length              0005 (5)
│ │ │ │ -9F6E7   Flags               01 (1) 'Modification'
│ │ │ │ -9F6E8   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F6EC Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F6EE   Length              000B (11)
│ │ │ │ -9F6F0   Version             01 (1)
│ │ │ │ -9F6F1   UID Size            04 (4)
│ │ │ │ -9F6F2   UID                 00000000 (0)
│ │ │ │ -9F6F6   GID Size            04 (4)
│ │ │ │ -9F6F7   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F6FB CENTRAL HEADER #76    02014B50 (33639248)
│ │ │ │ -9F6FF Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F700 Created OS            03 (3) 'Unix'
│ │ │ │ -9F701 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F702 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F703 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F705 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F707 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F70B CRC                   EAA681B2 (3936780722)
│ │ │ │ -9F70F Compressed Size       000016FB (5883)
│ │ │ │ -9F713 Uncompressed Size     00008AB6 (35510)
│ │ │ │ -9F717 Filename Length       0012 (18)
│ │ │ │ -9F719 Extra Length          0018 (24)
│ │ │ │ -9F71B Comment Length        0000 (0)
│ │ │ │ -9F71D Disk Start            0000 (0)
│ │ │ │ -9F71F Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F721 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F725 Local Header Offset   00086152 (549202)
│ │ │ │ -9F729 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F729: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F73B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F73D   Length              0005 (5)
│ │ │ │ -9F73F   Flags               01 (1) 'Modification'
│ │ │ │ -9F740   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F744 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F746   Length              000B (11)
│ │ │ │ -9F748   Version             01 (1)
│ │ │ │ -9F749   UID Size            04 (4)
│ │ │ │ -9F74A   UID                 00000000 (0)
│ │ │ │ -9F74E   GID Size            04 (4)
│ │ │ │ -9F74F   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F753 CENTRAL HEADER #77    02014B50 (33639248)
│ │ │ │ -9F757 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F758 Created OS            03 (3) 'Unix'
│ │ │ │ -9F759 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F75A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F75B General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F75D Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F75F Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F763 CRC                   2B5B6715 (727410453)
│ │ │ │ -9F767 Compressed Size       00001E12 (7698)
│ │ │ │ -9F76B Uncompressed Size     00008803 (34819)
│ │ │ │ -9F76F Filename Length       0016 (22)
│ │ │ │ -9F771 Extra Length          0018 (24)
│ │ │ │ -9F773 Comment Length        0000 (0)
│ │ │ │ -9F775 Disk Start            0000 (0)
│ │ │ │ -9F777 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F779 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F77D Local Header Offset   00087899 (555161)
│ │ │ │ -9F781 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F781: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F797 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F799   Length              0005 (5)
│ │ │ │ -9F79B   Flags               01 (1) 'Modification'
│ │ │ │ -9F79C   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F7A0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F7A2   Length              000B (11)
│ │ │ │ -9F7A4   Version             01 (1)
│ │ │ │ -9F7A5   UID Size            04 (4)
│ │ │ │ -9F7A6   UID                 00000000 (0)
│ │ │ │ -9F7AA   GID Size            04 (4)
│ │ │ │ -9F7AB   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F7AF CENTRAL HEADER #78    02014B50 (33639248)
│ │ │ │ -9F7B3 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F7B4 Created OS            03 (3) 'Unix'
│ │ │ │ -9F7B5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F7B6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F7B7 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F7B9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F7BB Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F7BF CRC                   F1BBDD3F (4055620927)
│ │ │ │ -9F7C3 Compressed Size       000029A9 (10665)
│ │ │ │ -9F7C7 Uncompressed Size     0000D04F (53327)
│ │ │ │ -9F7CB Filename Length       001A (26)
│ │ │ │ -9F7CD Extra Length          0018 (24)
│ │ │ │ -9F7CF Comment Length        0000 (0)
│ │ │ │ -9F7D1 Disk Start            0000 (0)
│ │ │ │ -9F7D3 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F7D5 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F7D9 Local Header Offset   000896FB (562939)
│ │ │ │ -9F7DD Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F7DD: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F7F7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F7F9   Length              0005 (5)
│ │ │ │ -9F7FB   Flags               01 (1) 'Modification'
│ │ │ │ -9F7FC   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F800 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F802   Length              000B (11)
│ │ │ │ -9F804   Version             01 (1)
│ │ │ │ -9F805   UID Size            04 (4)
│ │ │ │ -9F806   UID                 00000000 (0)
│ │ │ │ -9F80A   GID Size            04 (4)
│ │ │ │ -9F80B   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F80F CENTRAL HEADER #79    02014B50 (33639248)
│ │ │ │ -9F813 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F814 Created OS            03 (3) 'Unix'
│ │ │ │ -9F815 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F816 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F817 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F819 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F81B Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F81F CRC                   DC838374 (3699606388)
│ │ │ │ -9F823 Compressed Size       000009AB (2475)
│ │ │ │ -9F827 Uncompressed Size     00001DB6 (7606)
│ │ │ │ -9F82B Filename Length       0018 (24)
│ │ │ │ -9F82D Extra Length          0018 (24)
│ │ │ │ -9F82F Comment Length        0000 (0)
│ │ │ │ -9F831 Disk Start            0000 (0)
│ │ │ │ -9F833 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F835 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F839 Local Header Offset   0008C0F8 (573688)
│ │ │ │ -9F83D Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F83D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F855 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F857   Length              0005 (5)
│ │ │ │ -9F859   Flags               01 (1) 'Modification'
│ │ │ │ -9F85A   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F85E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F860   Length              000B (11)
│ │ │ │ -9F862   Version             01 (1)
│ │ │ │ -9F863   UID Size            04 (4)
│ │ │ │ -9F864   UID                 00000000 (0)
│ │ │ │ -9F868   GID Size            04 (4)
│ │ │ │ -9F869   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F86D CENTRAL HEADER #80    02014B50 (33639248)
│ │ │ │ -9F871 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F872 Created OS            03 (3) 'Unix'
│ │ │ │ -9F873 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F874 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F875 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F877 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F879 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F87D CRC                   F5E2129F (4125233823)
│ │ │ │ -9F881 Compressed Size       000016BC (5820)
│ │ │ │ -9F885 Uncompressed Size     000016CD (5837)
│ │ │ │ -9F889 Filename Length       0015 (21)
│ │ │ │ -9F88B Extra Length          0018 (24)
│ │ │ │ -9F88D Comment Length        0000 (0)
│ │ │ │ -9F88F Disk Start            0000 (0)
│ │ │ │ -9F891 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F893 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F897 Local Header Offset   0008CAF5 (576245)
│ │ │ │ -9F89B Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F89B: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F8B0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F8B2   Length              0005 (5)
│ │ │ │ -9F8B4   Flags               01 (1) 'Modification'
│ │ │ │ -9F8B5   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F8B9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F8BB   Length              000B (11)
│ │ │ │ -9F8BD   Version             01 (1)
│ │ │ │ -9F8BE   UID Size            04 (4)
│ │ │ │ -9F8BF   UID                 00000000 (0)
│ │ │ │ -9F8C3   GID Size            04 (4)
│ │ │ │ -9F8C4   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F8C8 CENTRAL HEADER #81    02014B50 (33639248)
│ │ │ │ -9F8CC Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F8CD Created OS            03 (3) 'Unix'
│ │ │ │ -9F8CE Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9F8CF Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F8D0 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9F8D2 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9F8D4 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F8D8 CRC                   F5E2129F (4125233823)
│ │ │ │ -9F8DC Compressed Size       000016BC (5820)
│ │ │ │ -9F8E0 Uncompressed Size     000016CD (5837)
│ │ │ │ -9F8E4 Filename Length       001C (28)
│ │ │ │ -9F8E6 Extra Length          0018 (24)
│ │ │ │ -9F8E8 Comment Length        0000 (0)
│ │ │ │ -9F8EA Disk Start            0000 (0)
│ │ │ │ -9F8EC Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F8EE Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F8F2 Local Header Offset   0008E200 (582144)
│ │ │ │ -9F8F6 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F8F6: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F912 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F914   Length              0005 (5)
│ │ │ │ -9F916   Flags               01 (1) 'Modification'
│ │ │ │ -9F917   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F91B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F91D   Length              000B (11)
│ │ │ │ -9F91F   Version             01 (1)
│ │ │ │ -9F920   UID Size            04 (4)
│ │ │ │ -9F921   UID                 00000000 (0)
│ │ │ │ -9F925   GID Size            04 (4)
│ │ │ │ -9F926   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F92A CENTRAL HEADER #82    02014B50 (33639248)
│ │ │ │ -9F92E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F92F Created OS            03 (3) 'Unix'
│ │ │ │ -9F930 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9F931 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F932 General Purpose Flag  0000 (0)
│ │ │ │ -9F934 Compression Method    0000 (0) 'Stored'
│ │ │ │ -9F936 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F93A CRC                   FC95F24B (4237685323)
│ │ │ │ -9F93E Compressed Size       00001B84 (7044)
│ │ │ │ -9F942 Uncompressed Size     00001B84 (7044)
│ │ │ │ -9F946 Filename Length       0016 (22)
│ │ │ │ -9F948 Extra Length          0018 (24)
│ │ │ │ -9F94A Comment Length        0000 (0)
│ │ │ │ -9F94C Disk Start            0000 (0)
│ │ │ │ -9F94E Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F950 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F954 Local Header Offset   0008F912 (588050)
│ │ │ │ -9F958 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F958: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F96E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F970   Length              0005 (5)
│ │ │ │ -9F972   Flags               01 (1) 'Modification'
│ │ │ │ -9F973   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F977 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F979   Length              000B (11)
│ │ │ │ -9F97B   Version             01 (1)
│ │ │ │ -9F97C   UID Size            04 (4)
│ │ │ │ -9F97D   UID                 00000000 (0)
│ │ │ │ -9F981   GID Size            04 (4)
│ │ │ │ -9F982   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F986 CENTRAL HEADER #83    02014B50 (33639248)
│ │ │ │ -9F98A Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F98B Created OS            03 (3) 'Unix'
│ │ │ │ -9F98C Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9F98D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F98E General Purpose Flag  0000 (0)
│ │ │ │ -9F990 Compression Method    0000 (0) 'Stored'
│ │ │ │ -9F992 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F996 CRC                   D0D71F86 (3503759238)
│ │ │ │ -9F99A Compressed Size       00000B7B (2939)
│ │ │ │ -9F99E Uncompressed Size     00000B7B (2939)
│ │ │ │ -9F9A2 Filename Length       0016 (22)
│ │ │ │ -9F9A4 Extra Length          0018 (24)
│ │ │ │ -9F9A6 Comment Length        0000 (0)
│ │ │ │ -9F9A8 Disk Start            0000 (0)
│ │ │ │ -9F9AA Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9F9AC Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9F9B0 Local Header Offset   000914E6 (595174)
│ │ │ │ -9F9B4 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9F9B4: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9F9CA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9F9CC   Length              0005 (5)
│ │ │ │ -9F9CE   Flags               01 (1) 'Modification'
│ │ │ │ -9F9CF   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9F9D3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9F9D5   Length              000B (11)
│ │ │ │ -9F9D7   Version             01 (1)
│ │ │ │ -9F9D8   UID Size            04 (4)
│ │ │ │ -9F9D9   UID                 00000000 (0)
│ │ │ │ -9F9DD   GID Size            04 (4)
│ │ │ │ -9F9DE   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9F9E2 CENTRAL HEADER #84    02014B50 (33639248)
│ │ │ │ -9F9E6 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9F9E7 Created OS            03 (3) 'Unix'
│ │ │ │ -9F9E8 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9F9E9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9F9EA General Purpose Flag  0000 (0)
│ │ │ │ -9F9EC Compression Method    0000 (0) 'Stored'
│ │ │ │ -9F9EE Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9F9F2 CRC                   FFF9C4D2 (4294558930)
│ │ │ │ -9F9F6 Compressed Size       0000138F (5007)
│ │ │ │ -9F9FA Uncompressed Size     0000138F (5007)
│ │ │ │ -9F9FE Filename Length       0016 (22)
│ │ │ │ -9FA00 Extra Length          0018 (24)
│ │ │ │ -9FA02 Comment Length        0000 (0)
│ │ │ │ -9FA04 Disk Start            0000 (0)
│ │ │ │ -9FA06 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FA08 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FA0C Local Header Offset   000920B1 (598193)
│ │ │ │ -9FA10 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FA10: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FA26 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FA28   Length              0005 (5)
│ │ │ │ -9FA2A   Flags               01 (1) 'Modification'
│ │ │ │ -9FA2B   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FA2F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FA31   Length              000B (11)
│ │ │ │ -9FA33   Version             01 (1)
│ │ │ │ -9FA34   UID Size            04 (4)
│ │ │ │ -9FA35   UID                 00000000 (0)
│ │ │ │ -9FA39   GID Size            04 (4)
│ │ │ │ -9FA3A   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FA3E CENTRAL HEADER #85    02014B50 (33639248)
│ │ │ │ -9FA42 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9FA43 Created OS            03 (3) 'Unix'
│ │ │ │ -9FA44 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9FA45 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9FA46 General Purpose Flag  0000 (0)
│ │ │ │ -9FA48 Compression Method    0000 (0) 'Stored'
│ │ │ │ -9FA4A Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9FA4E CRC                   A1037E8E (2701360782)
│ │ │ │ -9FA52 Compressed Size       0000145E (5214)
│ │ │ │ -9FA56 Uncompressed Size     0000145E (5214)
│ │ │ │ -9FA5A Filename Length       0016 (22)
│ │ │ │ -9FA5C Extra Length          0018 (24)
│ │ │ │ -9FA5E Comment Length        0000 (0)
│ │ │ │ -9FA60 Disk Start            0000 (0)
│ │ │ │ -9FA62 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FA64 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FA68 Local Header Offset   00093490 (603280)
│ │ │ │ -9FA6C Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FA6C: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FA82 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FA84   Length              0005 (5)
│ │ │ │ -9FA86   Flags               01 (1) 'Modification'
│ │ │ │ -9FA87   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FA8B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FA8D   Length              000B (11)
│ │ │ │ -9FA8F   Version             01 (1)
│ │ │ │ -9FA90   UID Size            04 (4)
│ │ │ │ -9FA91   UID                 00000000 (0)
│ │ │ │ -9FA95   GID Size            04 (4)
│ │ │ │ -9FA96   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FA9A CENTRAL HEADER #86    02014B50 (33639248)
│ │ │ │ -9FA9E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9FA9F Created OS            03 (3) 'Unix'
│ │ │ │ -9FAA0 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9FAA1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9FAA2 General Purpose Flag  0000 (0)
│ │ │ │ -9FAA4 Compression Method    0000 (0) 'Stored'
│ │ │ │ -9FAA6 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9FAAA CRC                   5E9E64F1 (1587438833)
│ │ │ │ -9FAAE Compressed Size       000008EC (2284)
│ │ │ │ -9FAB2 Uncompressed Size     000008EC (2284)
│ │ │ │ -9FAB6 Filename Length       0016 (22)
│ │ │ │ -9FAB8 Extra Length          0018 (24)
│ │ │ │ -9FABA Comment Length        0000 (0)
│ │ │ │ -9FABC Disk Start            0000 (0)
│ │ │ │ -9FABE Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FAC0 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FAC4 Local Header Offset   0009493E (608574)
│ │ │ │ -9FAC8 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FAC8: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FADE Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FAE0   Length              0005 (5)
│ │ │ │ -9FAE2   Flags               01 (1) 'Modification'
│ │ │ │ -9FAE3   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FAE7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FAE9   Length              000B (11)
│ │ │ │ -9FAEB   Version             01 (1)
│ │ │ │ -9FAEC   UID Size            04 (4)
│ │ │ │ -9FAED   UID                 00000000 (0)
│ │ │ │ -9FAF1   GID Size            04 (4)
│ │ │ │ -9FAF2   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FAF6 CENTRAL HEADER #87    02014B50 (33639248)
│ │ │ │ -9FAFA Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9FAFB Created OS            03 (3) 'Unix'
│ │ │ │ -9FAFC Extract Zip Spec      0A (10) '1.0'
│ │ │ │ -9FAFD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9FAFE General Purpose Flag  0000 (0)
│ │ │ │ -9FB00 Compression Method    0000 (0) 'Stored'
│ │ │ │ -9FB02 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9FB06 CRC                   42E340AB (1122189483)
│ │ │ │ -9FB0A Compressed Size       00001F2E (7982)
│ │ │ │ -9FB0E Uncompressed Size     00001F2E (7982)
│ │ │ │ -9FB12 Filename Length       001E (30)
│ │ │ │ -9FB14 Extra Length          0018 (24)
│ │ │ │ -9FB16 Comment Length        0000 (0)
│ │ │ │ -9FB18 Disk Start            0000 (0)
│ │ │ │ -9FB1A Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FB1C Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FB20 Local Header Offset   0009527A (610938)
│ │ │ │ -9FB24 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FB24: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FB42 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FB44   Length              0005 (5)
│ │ │ │ -9FB46   Flags               01 (1) 'Modification'
│ │ │ │ -9FB47   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FB4B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FB4D   Length              000B (11)
│ │ │ │ -9FB4F   Version             01 (1)
│ │ │ │ -9FB50   UID Size            04 (4)
│ │ │ │ -9FB51   UID                 00000000 (0)
│ │ │ │ -9FB55   GID Size            04 (4)
│ │ │ │ -9FB56   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FB5A CENTRAL HEADER #88    02014B50 (33639248)
│ │ │ │ -9FB5E Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9FB5F Created OS            03 (3) 'Unix'
│ │ │ │ -9FB60 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9FB61 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9FB62 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9FB64 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9FB66 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9FB6A CRC                   46D4ADFC (1188343292)
│ │ │ │ -9FB6E Compressed Size       00003D71 (15729)
│ │ │ │ -9FB72 Uncompressed Size     00016649 (91721)
│ │ │ │ -9FB76 Filename Length       001A (26)
│ │ │ │ -9FB78 Extra Length          0018 (24)
│ │ │ │ -9FB7A Comment Length        0000 (0)
│ │ │ │ -9FB7C Disk Start            0000 (0)
│ │ │ │ -9FB7E Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FB80 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FB84 Local Header Offset   00097200 (619008)
│ │ │ │ -9FB88 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FB88: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FBA2 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FBA4   Length              0005 (5)
│ │ │ │ -9FBA6   Flags               01 (1) 'Modification'
│ │ │ │ -9FBA7   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FBAB Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FBAD   Length              000B (11)
│ │ │ │ -9FBAF   Version             01 (1)
│ │ │ │ -9FBB0   UID Size            04 (4)
│ │ │ │ -9FBB1   UID                 00000000 (0)
│ │ │ │ -9FBB5   GID Size            04 (4)
│ │ │ │ -9FBB6   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FBBA CENTRAL HEADER #89    02014B50 (33639248)
│ │ │ │ -9FBBE Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9FBBF Created OS            03 (3) 'Unix'
│ │ │ │ -9FBC0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9FBC1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9FBC2 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9FBC4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9FBC6 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9FBCA CRC                   228F80DD (579829981)
│ │ │ │ -9FBCE Compressed Size       000029BF (10687)
│ │ │ │ -9FBD2 Uncompressed Size     0000BA6A (47722)
│ │ │ │ -9FBD6 Filename Length       0018 (24)
│ │ │ │ -9FBD8 Extra Length          0018 (24)
│ │ │ │ -9FBDA Comment Length        0000 (0)
│ │ │ │ -9FBDC Disk Start            0000 (0)
│ │ │ │ -9FBDE Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FBE0 Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FBE4 Local Header Offset   0009AFC5 (634821)
│ │ │ │ -9FBE8 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FBE8: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FC00 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FC02   Length              0005 (5)
│ │ │ │ -9FC04   Flags               01 (1) 'Modification'
│ │ │ │ -9FC05   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FC09 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FC0B   Length              000B (11)
│ │ │ │ -9FC0D   Version             01 (1)
│ │ │ │ -9FC0E   UID Size            04 (4)
│ │ │ │ -9FC0F   UID                 00000000 (0)
│ │ │ │ -9FC13   GID Size            04 (4)
│ │ │ │ -9FC14   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FC18 CENTRAL HEADER #90    02014B50 (33639248)
│ │ │ │ -9FC1C Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9FC1D Created OS            03 (3) 'Unix'
│ │ │ │ -9FC1E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9FC1F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9FC20 General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9FC22 Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9FC24 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9FC28 CRC                   DCB3B516 (3702764822)
│ │ │ │ -9FC2C Compressed Size       000000AE (174)
│ │ │ │ -9FC30 Uncompressed Size     000000FC (252)
│ │ │ │ -9FC34 Filename Length       0016 (22)
│ │ │ │ -9FC36 Extra Length          0018 (24)
│ │ │ │ -9FC38 Comment Length        0000 (0)
│ │ │ │ -9FC3A Disk Start            0000 (0)
│ │ │ │ -9FC3C Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FC3E Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FC42 Local Header Offset   0009D9D6 (645590)
│ │ │ │ -9FC46 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FC46: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FC5C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FC5E   Length              0005 (5)
│ │ │ │ -9FC60   Flags               01 (1) 'Modification'
│ │ │ │ -9FC61   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FC65 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FC67   Length              000B (11)
│ │ │ │ -9FC69   Version             01 (1)
│ │ │ │ -9FC6A   UID Size            04 (4)
│ │ │ │ -9FC6B   UID                 00000000 (0)
│ │ │ │ -9FC6F   GID Size            04 (4)
│ │ │ │ -9FC70   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FC74 CENTRAL HEADER #91    02014B50 (33639248)
│ │ │ │ -9FC78 Created Zip Spec      3D (61) '6.1'
│ │ │ │ -9FC79 Created OS            03 (3) 'Unix'
│ │ │ │ -9FC7A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ -9FC7B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ -9FC7C General Purpose Flag  0000 (0)
│ │ │ │ -      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ -9FC7E Compression Method    0008 (8) 'Deflated'
│ │ │ │ -9FC80 Modification Time     5B5F6A46 (1532979782) 'Fri Oct 31 13:18:12 2025'
│ │ │ │ -9FC84 CRC                   58439733 (1480824627)
│ │ │ │ -9FC88 Compressed Size       00000077 (119)
│ │ │ │ -9FC8C Uncompressed Size     000000A2 (162)
│ │ │ │ -9FC90 Filename Length       002D (45)
│ │ │ │ -9FC92 Extra Length          0018 (24)
│ │ │ │ -9FC94 Comment Length        0000 (0)
│ │ │ │ -9FC96 Disk Start            0000 (0)
│ │ │ │ -9FC98 Int File Attributes   0000 (0)
│ │ │ │ -      [Bit 0]               0 'Binary Data'
│ │ │ │ -9FC9A Ext File Attributes   01A40000 (27525120)
│ │ │ │ -      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ -9FC9E Local Header Offset   0009DAD4 (645844)
│ │ │ │ -9FCA2 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#
│ │ │ │ -# WARNING: Offset 0x9FCA2: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ -#          Zero length filename
│ │ │ │ -#
│ │ │ │ -9FCCF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ -9FCD1   Length              0005 (5)
│ │ │ │ -9FCD3   Flags               01 (1) 'Modification'
│ │ │ │ -9FCD4   Modification Time   6904B715 (1761916693) 'Fri Oct 31 13:18:13 2025'
│ │ │ │ -9FCD8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ -9FCDA   Length              000B (11)
│ │ │ │ -9FCDC   Version             01 (1)
│ │ │ │ -9FCDD   UID Size            04 (4)
│ │ │ │ -9FCDE   UID                 00000000 (0)
│ │ │ │ -9FCE2   GID Size            04 (4)
│ │ │ │ -9FCE3   GID                 00000000 (0)
│ │ │ │ -
│ │ │ │ -9FCE7 END CENTRAL HEADER    06054B50 (101010256)
│ │ │ │ -9FCEB Number of this disk   0000 (0)
│ │ │ │ -9FCED Central Dir Disk no   0000 (0)
│ │ │ │ -9FCEF Entries in this disk  005B (91)
│ │ │ │ -9FCF1 Total Entries         005B (91)
│ │ │ │ -9FCF3 Size of Central Dir   00002135 (8501)
│ │ │ │ -9FCF7 Offset to Central Dir 0009DBB2 (646066)
│ │ │ │ -9FCFB Comment Length        0000 (0)
│ │ │ │ +9DAF9 LOCAL HEADER #91      04034B50 (67324752)
│ │ │ │ +9DAFD Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DAFE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DAFF General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DB01 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DB03 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DB07 CRC                   58439733 (1480824627)
│ │ │ │ +9DB0B Compressed Size       00000077 (119)
│ │ │ │ +9DB0F Uncompressed Size     000000A2 (162)
│ │ │ │ +9DB13 Filename Length       002D (45)
│ │ │ │ +9DB15 Extra Length          001C (28)
│ │ │ │ +9DB17 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DB17: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DB44 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DB46   Length              0009 (9)
│ │ │ │ +9DB48   Flags               03 (3) 'Modification Access'
│ │ │ │ +9DB49   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DB4D   Access Time         6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DB51 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DB53   Length              000B (11)
│ │ │ │ +9DB55   Version             01 (1)
│ │ │ │ +9DB56   UID Size            04 (4)
│ │ │ │ +9DB57   UID                 00000000 (0)
│ │ │ │ +9DB5B   GID Size            04 (4)
│ │ │ │ +9DB5C   GID                 00000000 (0)
│ │ │ │ +9DB60 PAYLOAD               XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
│ │ │ │ +
│ │ │ │ +9DBD7 CENTRAL HEADER #1     02014B50 (33639248)
│ │ │ │ +9DBDB Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DBDC Created OS            03 (3) 'Unix'
│ │ │ │ +9DBDD Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +9DBDE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DBDF General Purpose Flag  0000 (0)
│ │ │ │ +9DBE1 Compression Method    0000 (0) 'Stored'
│ │ │ │ +9DBE3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DBE7 CRC                   2CAB616F (749429103)
│ │ │ │ +9DBEB Compressed Size       00000014 (20)
│ │ │ │ +9DBEF Uncompressed Size     00000014 (20)
│ │ │ │ +9DBF3 Filename Length       0008 (8)
│ │ │ │ +9DBF5 Extra Length          0018 (24)
│ │ │ │ +9DBF7 Comment Length        0000 (0)
│ │ │ │ +9DBF9 Disk Start            0000 (0)
│ │ │ │ +9DBFB Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DBFD Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DC01 Local Header Offset   00000000 (0)
│ │ │ │ +9DC05 Filename              'XXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DC05: Filename 'XXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DC0D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DC0F   Length              0005 (5)
│ │ │ │ +9DC11   Flags               01 (1) 'Modification'
│ │ │ │ +9DC12   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DC16 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DC18   Length              000B (11)
│ │ │ │ +9DC1A   Version             01 (1)
│ │ │ │ +9DC1B   UID Size            04 (4)
│ │ │ │ +9DC1C   UID                 00000000 (0)
│ │ │ │ +9DC20   GID Size            04 (4)
│ │ │ │ +9DC21   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DC25 CENTRAL HEADER #2     02014B50 (33639248)
│ │ │ │ +9DC29 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DC2A Created OS            03 (3) 'Unix'
│ │ │ │ +9DC2B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DC2C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DC2D General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DC2F Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DC31 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DC35 CRC                   203D4469 (540886121)
│ │ │ │ +9DC39 Compressed Size       000015AD (5549)
│ │ │ │ +9DC3D Uncompressed Size     00004602 (17922)
│ │ │ │ +9DC41 Filename Length       0014 (20)
│ │ │ │ +9DC43 Extra Length          0018 (24)
│ │ │ │ +9DC45 Comment Length        0000 (0)
│ │ │ │ +9DC47 Disk Start            0000 (0)
│ │ │ │ +9DC49 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DC4B Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DC4F Local Header Offset   00000056 (86)
│ │ │ │ +9DC53 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DC53: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DC67 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DC69   Length              0005 (5)
│ │ │ │ +9DC6B   Flags               01 (1) 'Modification'
│ │ │ │ +9DC6C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DC70 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DC72   Length              000B (11)
│ │ │ │ +9DC74   Version             01 (1)
│ │ │ │ +9DC75   UID Size            04 (4)
│ │ │ │ +9DC76   UID                 00000000 (0)
│ │ │ │ +9DC7A   GID Size            04 (4)
│ │ │ │ +9DC7B   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DC7F CENTRAL HEADER #3     02014B50 (33639248)
│ │ │ │ +9DC83 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DC84 Created OS            03 (3) 'Unix'
│ │ │ │ +9DC85 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DC86 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DC87 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DC89 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DC8B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DC8F CRC                   1EC1D7C5 (516020165)
│ │ │ │ +9DC93 Compressed Size       000006D5 (1749)
│ │ │ │ +9DC97 Uncompressed Size     00001241 (4673)
│ │ │ │ +9DC9B Filename Length       0013 (19)
│ │ │ │ +9DC9D Extra Length          0018 (24)
│ │ │ │ +9DC9F Comment Length        0000 (0)
│ │ │ │ +9DCA1 Disk Start            0000 (0)
│ │ │ │ +9DCA3 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DCA5 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DCA9 Local Header Offset   00001651 (5713)
│ │ │ │ +9DCAD Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DCAD: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DCC0 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DCC2   Length              0005 (5)
│ │ │ │ +9DCC4   Flags               01 (1) 'Modification'
│ │ │ │ +9DCC5   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DCC9 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DCCB   Length              000B (11)
│ │ │ │ +9DCCD   Version             01 (1)
│ │ │ │ +9DCCE   UID Size            04 (4)
│ │ │ │ +9DCCF   UID                 00000000 (0)
│ │ │ │ +9DCD3   GID Size            04 (4)
│ │ │ │ +9DCD4   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DCD8 CENTRAL HEADER #4     02014B50 (33639248)
│ │ │ │ +9DCDC Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DCDD Created OS            03 (3) 'Unix'
│ │ │ │ +9DCDE Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DCDF Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DCE0 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DCE2 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DCE4 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DCE8 CRC                   7FB0954F (2142278991)
│ │ │ │ +9DCEC Compressed Size       00002DA0 (11680)
│ │ │ │ +9DCF0 Uncompressed Size     0000D0BF (53439)
│ │ │ │ +9DCF4 Filename Length       0014 (20)
│ │ │ │ +9DCF6 Extra Length          0018 (24)
│ │ │ │ +9DCF8 Comment Length        0000 (0)
│ │ │ │ +9DCFA Disk Start            0000 (0)
│ │ │ │ +9DCFC Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DCFE Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DD02 Local Header Offset   00001D73 (7539)
│ │ │ │ +9DD06 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DD06: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DD1A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DD1C   Length              0005 (5)
│ │ │ │ +9DD1E   Flags               01 (1) 'Modification'
│ │ │ │ +9DD1F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DD23 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DD25   Length              000B (11)
│ │ │ │ +9DD27   Version             01 (1)
│ │ │ │ +9DD28   UID Size            04 (4)
│ │ │ │ +9DD29   UID                 00000000 (0)
│ │ │ │ +9DD2D   GID Size            04 (4)
│ │ │ │ +9DD2E   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DD32 CENTRAL HEADER #5     02014B50 (33639248)
│ │ │ │ +9DD36 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DD37 Created OS            03 (3) 'Unix'
│ │ │ │ +9DD38 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DD39 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DD3A General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DD3C Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DD3E Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DD42 CRC                   B8F4A452 (3103040594)
│ │ │ │ +9DD46 Compressed Size       000003F0 (1008)
│ │ │ │ +9DD4A Uncompressed Size     00000876 (2166)
│ │ │ │ +9DD4E Filename Length       0014 (20)
│ │ │ │ +9DD50 Extra Length          0018 (24)
│ │ │ │ +9DD52 Comment Length        0000 (0)
│ │ │ │ +9DD54 Disk Start            0000 (0)
│ │ │ │ +9DD56 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DD58 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DD5C Local Header Offset   00004B61 (19297)
│ │ │ │ +9DD60 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DD60: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DD74 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DD76   Length              0005 (5)
│ │ │ │ +9DD78   Flags               01 (1) 'Modification'
│ │ │ │ +9DD79   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DD7D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DD7F   Length              000B (11)
│ │ │ │ +9DD81   Version             01 (1)
│ │ │ │ +9DD82   UID Size            04 (4)
│ │ │ │ +9DD83   UID                 00000000 (0)
│ │ │ │ +9DD87   GID Size            04 (4)
│ │ │ │ +9DD88   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DD8C CENTRAL HEADER #6     02014B50 (33639248)
│ │ │ │ +9DD90 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DD91 Created OS            03 (3) 'Unix'
│ │ │ │ +9DD92 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DD93 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DD94 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DD96 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DD98 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DD9C CRC                   D32DA388 (3542983560)
│ │ │ │ +9DDA0 Compressed Size       000001AE (430)
│ │ │ │ +9DDA4 Uncompressed Size     000002FC (764)
│ │ │ │ +9DDA8 Filename Length       0011 (17)
│ │ │ │ +9DDAA Extra Length          0018 (24)
│ │ │ │ +9DDAC Comment Length        0000 (0)
│ │ │ │ +9DDAE Disk Start            0000 (0)
│ │ │ │ +9DDB0 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DDB2 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DDB6 Local Header Offset   00004F9F (20383)
│ │ │ │ +9DDBA Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DDBA: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DDCB Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DDCD   Length              0005 (5)
│ │ │ │ +9DDCF   Flags               01 (1) 'Modification'
│ │ │ │ +9DDD0   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DDD4 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DDD6   Length              000B (11)
│ │ │ │ +9DDD8   Version             01 (1)
│ │ │ │ +9DDD9   UID Size            04 (4)
│ │ │ │ +9DDDA   UID                 00000000 (0)
│ │ │ │ +9DDDE   GID Size            04 (4)
│ │ │ │ +9DDDF   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DDE3 CENTRAL HEADER #7     02014B50 (33639248)
│ │ │ │ +9DDE7 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DDE8 Created OS            03 (3) 'Unix'
│ │ │ │ +9DDE9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DDEA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DDEB General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DDED Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DDEF Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DDF3 CRC                   BD3875EC (3174594028)
│ │ │ │ +9DDF7 Compressed Size       000020C4 (8388)
│ │ │ │ +9DDFB Uncompressed Size     0000B4B0 (46256)
│ │ │ │ +9DDFF Filename Length       001B (27)
│ │ │ │ +9DE01 Extra Length          0018 (24)
│ │ │ │ +9DE03 Comment Length        0000 (0)
│ │ │ │ +9DE05 Disk Start            0000 (0)
│ │ │ │ +9DE07 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DE09 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DE0D Local Header Offset   00005198 (20888)
│ │ │ │ +9DE11 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DE11: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DE2C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DE2E   Length              0005 (5)
│ │ │ │ +9DE30   Flags               01 (1) 'Modification'
│ │ │ │ +9DE31   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DE35 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DE37   Length              000B (11)
│ │ │ │ +9DE39   Version             01 (1)
│ │ │ │ +9DE3A   UID Size            04 (4)
│ │ │ │ +9DE3B   UID                 00000000 (0)
│ │ │ │ +9DE3F   GID Size            04 (4)
│ │ │ │ +9DE40   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DE44 CENTRAL HEADER #8     02014B50 (33639248)
│ │ │ │ +9DE48 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DE49 Created OS            03 (3) 'Unix'
│ │ │ │ +9DE4A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DE4B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DE4C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DE4E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DE50 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DE54 CRC                   CB35CCED (3409300717)
│ │ │ │ +9DE58 Compressed Size       00000E6F (3695)
│ │ │ │ +9DE5C Uncompressed Size     000030B2 (12466)
│ │ │ │ +9DE60 Filename Length       001D (29)
│ │ │ │ +9DE62 Extra Length          0018 (24)
│ │ │ │ +9DE64 Comment Length        0000 (0)
│ │ │ │ +9DE66 Disk Start            0000 (0)
│ │ │ │ +9DE68 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DE6A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DE6E Local Header Offset   000072B1 (29361)
│ │ │ │ +9DE72 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DE72: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DE8F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DE91   Length              0005 (5)
│ │ │ │ +9DE93   Flags               01 (1) 'Modification'
│ │ │ │ +9DE94   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DE98 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DE9A   Length              000B (11)
│ │ │ │ +9DE9C   Version             01 (1)
│ │ │ │ +9DE9D   UID Size            04 (4)
│ │ │ │ +9DE9E   UID                 00000000 (0)
│ │ │ │ +9DEA2   GID Size            04 (4)
│ │ │ │ +9DEA3   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DEA7 CENTRAL HEADER #9     02014B50 (33639248)
│ │ │ │ +9DEAB Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DEAC Created OS            03 (3) 'Unix'
│ │ │ │ +9DEAD Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DEAE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DEAF General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DEB1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DEB3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DEB7 CRC                   D01F57B3 (3491714995)
│ │ │ │ +9DEBB Compressed Size       00000972 (2418)
│ │ │ │ +9DEBF Uncompressed Size     00001CB2 (7346)
│ │ │ │ +9DEC3 Filename Length       0019 (25)
│ │ │ │ +9DEC5 Extra Length          0018 (24)
│ │ │ │ +9DEC7 Comment Length        0000 (0)
│ │ │ │ +9DEC9 Disk Start            0000 (0)
│ │ │ │ +9DECB Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DECD Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DED1 Local Header Offset   00008177 (33143)
│ │ │ │ +9DED5 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DED5: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DEEE Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DEF0   Length              0005 (5)
│ │ │ │ +9DEF2   Flags               01 (1) 'Modification'
│ │ │ │ +9DEF3   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DEF7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DEF9   Length              000B (11)
│ │ │ │ +9DEFB   Version             01 (1)
│ │ │ │ +9DEFC   UID Size            04 (4)
│ │ │ │ +9DEFD   UID                 00000000 (0)
│ │ │ │ +9DF01   GID Size            04 (4)
│ │ │ │ +9DF02   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DF06 CENTRAL HEADER #10    02014B50 (33639248)
│ │ │ │ +9DF0A Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DF0B Created OS            03 (3) 'Unix'
│ │ │ │ +9DF0C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DF0D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DF0E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DF10 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DF12 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DF16 CRC                   8FE86D92 (2414374290)
│ │ │ │ +9DF1A Compressed Size       00003880 (14464)
│ │ │ │ +9DF1E Uncompressed Size     0000F7F4 (63476)
│ │ │ │ +9DF22 Filename Length       0015 (21)
│ │ │ │ +9DF24 Extra Length          0018 (24)
│ │ │ │ +9DF26 Comment Length        0000 (0)
│ │ │ │ +9DF28 Disk Start            0000 (0)
│ │ │ │ +9DF2A Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DF2C Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DF30 Local Header Offset   00008B3C (35644)
│ │ │ │ +9DF34 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DF34: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DF49 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DF4B   Length              0005 (5)
│ │ │ │ +9DF4D   Flags               01 (1) 'Modification'
│ │ │ │ +9DF4E   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DF52 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DF54   Length              000B (11)
│ │ │ │ +9DF56   Version             01 (1)
│ │ │ │ +9DF57   UID Size            04 (4)
│ │ │ │ +9DF58   UID                 00000000 (0)
│ │ │ │ +9DF5C   GID Size            04 (4)
│ │ │ │ +9DF5D   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DF61 CENTRAL HEADER #11    02014B50 (33639248)
│ │ │ │ +9DF65 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DF66 Created OS            03 (3) 'Unix'
│ │ │ │ +9DF67 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DF68 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DF69 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DF6B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DF6D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DF71 CRC                   5D10F8D5 (1561393365)
│ │ │ │ +9DF75 Compressed Size       0000AAE5 (43749)
│ │ │ │ +9DF79 Uncompressed Size     0003DFDE (253918)
│ │ │ │ +9DF7D Filename Length       0012 (18)
│ │ │ │ +9DF7F Extra Length          0018 (24)
│ │ │ │ +9DF81 Comment Length        0000 (0)
│ │ │ │ +9DF83 Disk Start            0000 (0)
│ │ │ │ +9DF85 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DF87 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DF8B Local Header Offset   0000C40B (50187)
│ │ │ │ +9DF8F Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DF8F: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DFA1 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DFA3   Length              0005 (5)
│ │ │ │ +9DFA5   Flags               01 (1) 'Modification'
│ │ │ │ +9DFA6   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DFAA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9DFAC   Length              000B (11)
│ │ │ │ +9DFAE   Version             01 (1)
│ │ │ │ +9DFAF   UID Size            04 (4)
│ │ │ │ +9DFB0   UID                 00000000 (0)
│ │ │ │ +9DFB4   GID Size            04 (4)
│ │ │ │ +9DFB5   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9DFB9 CENTRAL HEADER #12    02014B50 (33639248)
│ │ │ │ +9DFBD Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9DFBE Created OS            03 (3) 'Unix'
│ │ │ │ +9DFBF Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9DFC0 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9DFC1 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9DFC3 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9DFC5 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9DFC9 CRC                   55F94B52 (1442401106)
│ │ │ │ +9DFCD Compressed Size       00003B1D (15133)
│ │ │ │ +9DFD1 Uncompressed Size     0001B2A0 (111264)
│ │ │ │ +9DFD5 Filename Length       0015 (21)
│ │ │ │ +9DFD7 Extra Length          0018 (24)
│ │ │ │ +9DFD9 Comment Length        0000 (0)
│ │ │ │ +9DFDB Disk Start            0000 (0)
│ │ │ │ +9DFDD Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9DFDF Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9DFE3 Local Header Offset   00016F3C (94012)
│ │ │ │ +9DFE7 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9DFE7: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9DFFC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9DFFE   Length              0005 (5)
│ │ │ │ +9E000   Flags               01 (1) 'Modification'
│ │ │ │ +9E001   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E005 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E007   Length              000B (11)
│ │ │ │ +9E009   Version             01 (1)
│ │ │ │ +9E00A   UID Size            04 (4)
│ │ │ │ +9E00B   UID                 00000000 (0)
│ │ │ │ +9E00F   GID Size            04 (4)
│ │ │ │ +9E010   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E014 CENTRAL HEADER #13    02014B50 (33639248)
│ │ │ │ +9E018 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E019 Created OS            03 (3) 'Unix'
│ │ │ │ +9E01A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E01B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E01C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E01E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E020 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E024 CRC                   C8304069 (3358605417)
│ │ │ │ +9E028 Compressed Size       00009082 (36994)
│ │ │ │ +9E02C Uncompressed Size     0003D05F (249951)
│ │ │ │ +9E030 Filename Length       0014 (20)
│ │ │ │ +9E032 Extra Length          0018 (24)
│ │ │ │ +9E034 Comment Length        0000 (0)
│ │ │ │ +9E036 Disk Start            0000 (0)
│ │ │ │ +9E038 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E03A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E03E Local Header Offset   0001AAA8 (109224)
│ │ │ │ +9E042 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E042: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E056 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E058   Length              0005 (5)
│ │ │ │ +9E05A   Flags               01 (1) 'Modification'
│ │ │ │ +9E05B   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E05F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E061   Length              000B (11)
│ │ │ │ +9E063   Version             01 (1)
│ │ │ │ +9E064   UID Size            04 (4)
│ │ │ │ +9E065   UID                 00000000 (0)
│ │ │ │ +9E069   GID Size            04 (4)
│ │ │ │ +9E06A   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E06E CENTRAL HEADER #14    02014B50 (33639248)
│ │ │ │ +9E072 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E073 Created OS            03 (3) 'Unix'
│ │ │ │ +9E074 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E075 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E076 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E078 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E07A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E07E CRC                   2482A8C2 (612542658)
│ │ │ │ +9E082 Compressed Size       00002A67 (10855)
│ │ │ │ +9E086 Uncompressed Size     0001151F (70943)
│ │ │ │ +9E08A Filename Length       0016 (22)
│ │ │ │ +9E08C Extra Length          0018 (24)
│ │ │ │ +9E08E Comment Length        0000 (0)
│ │ │ │ +9E090 Disk Start            0000 (0)
│ │ │ │ +9E092 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E094 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E098 Local Header Offset   00023B78 (146296)
│ │ │ │ +9E09C Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E09C: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E0B2 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E0B4   Length              0005 (5)
│ │ │ │ +9E0B6   Flags               01 (1) 'Modification'
│ │ │ │ +9E0B7   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E0BB Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E0BD   Length              000B (11)
│ │ │ │ +9E0BF   Version             01 (1)
│ │ │ │ +9E0C0   UID Size            04 (4)
│ │ │ │ +9E0C1   UID                 00000000 (0)
│ │ │ │ +9E0C5   GID Size            04 (4)
│ │ │ │ +9E0C6   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E0CA CENTRAL HEADER #15    02014B50 (33639248)
│ │ │ │ +9E0CE Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E0CF Created OS            03 (3) 'Unix'
│ │ │ │ +9E0D0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E0D1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E0D2 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E0D4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E0D6 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E0DA CRC                   29636121 (694378785)
│ │ │ │ +9E0DE Compressed Size       000014DA (5338)
│ │ │ │ +9E0E2 Uncompressed Size     00005176 (20854)
│ │ │ │ +9E0E6 Filename Length       001D (29)
│ │ │ │ +9E0E8 Extra Length          0018 (24)
│ │ │ │ +9E0EA Comment Length        0000 (0)
│ │ │ │ +9E0EC Disk Start            0000 (0)
│ │ │ │ +9E0EE Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E0F0 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E0F4 Local Header Offset   0002662F (157231)
│ │ │ │ +9E0F8 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E0F8: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E115 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E117   Length              0005 (5)
│ │ │ │ +9E119   Flags               01 (1) 'Modification'
│ │ │ │ +9E11A   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E11E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E120   Length              000B (11)
│ │ │ │ +9E122   Version             01 (1)
│ │ │ │ +9E123   UID Size            04 (4)
│ │ │ │ +9E124   UID                 00000000 (0)
│ │ │ │ +9E128   GID Size            04 (4)
│ │ │ │ +9E129   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E12D CENTRAL HEADER #16    02014B50 (33639248)
│ │ │ │ +9E131 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E132 Created OS            03 (3) 'Unix'
│ │ │ │ +9E133 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E134 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E135 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E137 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E139 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E13D CRC                   298D1A65 (697113189)
│ │ │ │ +9E141 Compressed Size       000037FC (14332)
│ │ │ │ +9E145 Uncompressed Size     0000E9F0 (59888)
│ │ │ │ +9E149 Filename Length       001C (28)
│ │ │ │ +9E14B Extra Length          0018 (24)
│ │ │ │ +9E14D Comment Length        0000 (0)
│ │ │ │ +9E14F Disk Start            0000 (0)
│ │ │ │ +9E151 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E153 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E157 Local Header Offset   00027B60 (162656)
│ │ │ │ +9E15B Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E15B: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E177 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E179   Length              0005 (5)
│ │ │ │ +9E17B   Flags               01 (1) 'Modification'
│ │ │ │ +9E17C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E180 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E182   Length              000B (11)
│ │ │ │ +9E184   Version             01 (1)
│ │ │ │ +9E185   UID Size            04 (4)
│ │ │ │ +9E186   UID                 00000000 (0)
│ │ │ │ +9E18A   GID Size            04 (4)
│ │ │ │ +9E18B   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E18F CENTRAL HEADER #17    02014B50 (33639248)
│ │ │ │ +9E193 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E194 Created OS            03 (3) 'Unix'
│ │ │ │ +9E195 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E196 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E197 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E199 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E19B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E19F CRC                   6A63C5E7 (1784923623)
│ │ │ │ +9E1A3 Compressed Size       000006A0 (1696)
│ │ │ │ +9E1A7 Uncompressed Size     000011F4 (4596)
│ │ │ │ +9E1AB Filename Length       001C (28)
│ │ │ │ +9E1AD Extra Length          0018 (24)
│ │ │ │ +9E1AF Comment Length        0000 (0)
│ │ │ │ +9E1B1 Disk Start            0000 (0)
│ │ │ │ +9E1B3 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E1B5 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E1B9 Local Header Offset   0002B3B2 (177074)
│ │ │ │ +9E1BD Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E1BD: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E1D9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E1DB   Length              0005 (5)
│ │ │ │ +9E1DD   Flags               01 (1) 'Modification'
│ │ │ │ +9E1DE   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E1E2 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E1E4   Length              000B (11)
│ │ │ │ +9E1E6   Version             01 (1)
│ │ │ │ +9E1E7   UID Size            04 (4)
│ │ │ │ +9E1E8   UID                 00000000 (0)
│ │ │ │ +9E1EC   GID Size            04 (4)
│ │ │ │ +9E1ED   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E1F1 CENTRAL HEADER #18    02014B50 (33639248)
│ │ │ │ +9E1F5 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E1F6 Created OS            03 (3) 'Unix'
│ │ │ │ +9E1F7 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E1F8 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E1F9 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E1FB Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E1FD Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E201 CRC                   F6FDE277 (4143833719)
│ │ │ │ +9E205 Compressed Size       0000107C (4220)
│ │ │ │ +9E209 Uncompressed Size     00004BFF (19455)
│ │ │ │ +9E20D Filename Length       001B (27)
│ │ │ │ +9E20F Extra Length          0018 (24)
│ │ │ │ +9E211 Comment Length        0000 (0)
│ │ │ │ +9E213 Disk Start            0000 (0)
│ │ │ │ +9E215 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E217 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E21B Local Header Offset   0002BAA8 (178856)
│ │ │ │ +9E21F Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E21F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E23A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E23C   Length              0005 (5)
│ │ │ │ +9E23E   Flags               01 (1) 'Modification'
│ │ │ │ +9E23F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E243 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E245   Length              000B (11)
│ │ │ │ +9E247   Version             01 (1)
│ │ │ │ +9E248   UID Size            04 (4)
│ │ │ │ +9E249   UID                 00000000 (0)
│ │ │ │ +9E24D   GID Size            04 (4)
│ │ │ │ +9E24E   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E252 CENTRAL HEADER #19    02014B50 (33639248)
│ │ │ │ +9E256 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E257 Created OS            03 (3) 'Unix'
│ │ │ │ +9E258 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E259 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E25A General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E25C Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E25E Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E262 CRC                   8F81EFC3 (2407657411)
│ │ │ │ +9E266 Compressed Size       000033AB (13227)
│ │ │ │ +9E26A Uncompressed Size     0000BC94 (48276)
│ │ │ │ +9E26E Filename Length       001D (29)
│ │ │ │ +9E270 Extra Length          0018 (24)
│ │ │ │ +9E272 Comment Length        0000 (0)
│ │ │ │ +9E274 Disk Start            0000 (0)
│ │ │ │ +9E276 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E278 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E27C Local Header Offset   0002CB79 (183161)
│ │ │ │ +9E280 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E280: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E29D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E29F   Length              0005 (5)
│ │ │ │ +9E2A1   Flags               01 (1) 'Modification'
│ │ │ │ +9E2A2   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E2A6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E2A8   Length              000B (11)
│ │ │ │ +9E2AA   Version             01 (1)
│ │ │ │ +9E2AB   UID Size            04 (4)
│ │ │ │ +9E2AC   UID                 00000000 (0)
│ │ │ │ +9E2B0   GID Size            04 (4)
│ │ │ │ +9E2B1   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E2B5 CENTRAL HEADER #20    02014B50 (33639248)
│ │ │ │ +9E2B9 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E2BA Created OS            03 (3) 'Unix'
│ │ │ │ +9E2BB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E2BC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E2BD General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E2BF Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E2C1 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E2C5 CRC                   F6188119 (4128801049)
│ │ │ │ +9E2C9 Compressed Size       00000D6B (3435)
│ │ │ │ +9E2CD Uncompressed Size     00003876 (14454)
│ │ │ │ +9E2D1 Filename Length       001D (29)
│ │ │ │ +9E2D3 Extra Length          0018 (24)
│ │ │ │ +9E2D5 Comment Length        0000 (0)
│ │ │ │ +9E2D7 Disk Start            0000 (0)
│ │ │ │ +9E2D9 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E2DB Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E2DF Local Header Offset   0002FF7B (196475)
│ │ │ │ +9E2E3 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E2E3: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E300 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E302   Length              0005 (5)
│ │ │ │ +9E304   Flags               01 (1) 'Modification'
│ │ │ │ +9E305   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E309 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E30B   Length              000B (11)
│ │ │ │ +9E30D   Version             01 (1)
│ │ │ │ +9E30E   UID Size            04 (4)
│ │ │ │ +9E30F   UID                 00000000 (0)
│ │ │ │ +9E313   GID Size            04 (4)
│ │ │ │ +9E314   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E318 CENTRAL HEADER #21    02014B50 (33639248)
│ │ │ │ +9E31C Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E31D Created OS            03 (3) 'Unix'
│ │ │ │ +9E31E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E31F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E320 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E322 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E324 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E328 CRC                   39EA28E4 (971647204)
│ │ │ │ +9E32C Compressed Size       00001C6C (7276)
│ │ │ │ +9E330 Uncompressed Size     0000C186 (49542)
│ │ │ │ +9E334 Filename Length       001A (26)
│ │ │ │ +9E336 Extra Length          0018 (24)
│ │ │ │ +9E338 Comment Length        0000 (0)
│ │ │ │ +9E33A Disk Start            0000 (0)
│ │ │ │ +9E33C Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E33E Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E342 Local Header Offset   00030D3D (199997)
│ │ │ │ +9E346 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E346: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E360 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E362   Length              0005 (5)
│ │ │ │ +9E364   Flags               01 (1) 'Modification'
│ │ │ │ +9E365   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E369 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E36B   Length              000B (11)
│ │ │ │ +9E36D   Version             01 (1)
│ │ │ │ +9E36E   UID Size            04 (4)
│ │ │ │ +9E36F   UID                 00000000 (0)
│ │ │ │ +9E373   GID Size            04 (4)
│ │ │ │ +9E374   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E378 CENTRAL HEADER #22    02014B50 (33639248)
│ │ │ │ +9E37C Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E37D Created OS            03 (3) 'Unix'
│ │ │ │ +9E37E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E37F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E380 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E382 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E384 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E388 CRC                   65574916 (1700219158)
│ │ │ │ +9E38C Compressed Size       000003A3 (931)
│ │ │ │ +9E390 Uncompressed Size     0000088E (2190)
│ │ │ │ +9E394 Filename Length       0012 (18)
│ │ │ │ +9E396 Extra Length          0018 (24)
│ │ │ │ +9E398 Comment Length        0000 (0)
│ │ │ │ +9E39A Disk Start            0000 (0)
│ │ │ │ +9E39C Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E39E Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E3A2 Local Header Offset   000329FD (207357)
│ │ │ │ +9E3A6 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E3A6: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E3B8 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E3BA   Length              0005 (5)
│ │ │ │ +9E3BC   Flags               01 (1) 'Modification'
│ │ │ │ +9E3BD   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E3C1 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E3C3   Length              000B (11)
│ │ │ │ +9E3C5   Version             01 (1)
│ │ │ │ +9E3C6   UID Size            04 (4)
│ │ │ │ +9E3C7   UID                 00000000 (0)
│ │ │ │ +9E3CB   GID Size            04 (4)
│ │ │ │ +9E3CC   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E3D0 CENTRAL HEADER #23    02014B50 (33639248)
│ │ │ │ +9E3D4 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E3D5 Created OS            03 (3) 'Unix'
│ │ │ │ +9E3D6 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E3D7 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E3D8 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E3DA Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E3DC Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E3E0 CRC                   83472134 (2202476852)
│ │ │ │ +9E3E4 Compressed Size       000001D4 (468)
│ │ │ │ +9E3E8 Uncompressed Size     00000311 (785)
│ │ │ │ +9E3EC Filename Length       0020 (32)
│ │ │ │ +9E3EE Extra Length          0018 (24)
│ │ │ │ +9E3F0 Comment Length        0000 (0)
│ │ │ │ +9E3F2 Disk Start            0000 (0)
│ │ │ │ +9E3F4 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E3F6 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E3FA Local Header Offset   00032DEC (208364)
│ │ │ │ +9E3FE Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E3FE: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E41E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E420   Length              0005 (5)
│ │ │ │ +9E422   Flags               01 (1) 'Modification'
│ │ │ │ +9E423   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E427 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E429   Length              000B (11)
│ │ │ │ +9E42B   Version             01 (1)
│ │ │ │ +9E42C   UID Size            04 (4)
│ │ │ │ +9E42D   UID                 00000000 (0)
│ │ │ │ +9E431   GID Size            04 (4)
│ │ │ │ +9E432   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E436 CENTRAL HEADER #24    02014B50 (33639248)
│ │ │ │ +9E43A Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E43B Created OS            03 (3) 'Unix'
│ │ │ │ +9E43C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E43D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E43E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E440 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E442 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E446 CRC                   97D21429 (2547127337)
│ │ │ │ +9E44A Compressed Size       000017AA (6058)
│ │ │ │ +9E44E Uncompressed Size     00009CD3 (40147)
│ │ │ │ +9E452 Filename Length       001B (27)
│ │ │ │ +9E454 Extra Length          0018 (24)
│ │ │ │ +9E456 Comment Length        0000 (0)
│ │ │ │ +9E458 Disk Start            0000 (0)
│ │ │ │ +9E45A Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E45C Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E460 Local Header Offset   0003301A (208922)
│ │ │ │ +9E464 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E464: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E47F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E481   Length              0005 (5)
│ │ │ │ +9E483   Flags               01 (1) 'Modification'
│ │ │ │ +9E484   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E488 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E48A   Length              000B (11)
│ │ │ │ +9E48C   Version             01 (1)
│ │ │ │ +9E48D   UID Size            04 (4)
│ │ │ │ +9E48E   UID                 00000000 (0)
│ │ │ │ +9E492   GID Size            04 (4)
│ │ │ │ +9E493   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E497 CENTRAL HEADER #25    02014B50 (33639248)
│ │ │ │ +9E49B Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E49C Created OS            03 (3) 'Unix'
│ │ │ │ +9E49D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E49E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E49F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E4A1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E4A3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E4A7 CRC                   5F73B5AE (1601418670)
│ │ │ │ +9E4AB Compressed Size       00001371 (4977)
│ │ │ │ +9E4AF Uncompressed Size     00003B66 (15206)
│ │ │ │ +9E4B3 Filename Length       0015 (21)
│ │ │ │ +9E4B5 Extra Length          0018 (24)
│ │ │ │ +9E4B7 Comment Length        0000 (0)
│ │ │ │ +9E4B9 Disk Start            0000 (0)
│ │ │ │ +9E4BB Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E4BD Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E4C1 Local Header Offset   00034819 (215065)
│ │ │ │ +9E4C5 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E4C5: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E4DA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E4DC   Length              0005 (5)
│ │ │ │ +9E4DE   Flags               01 (1) 'Modification'
│ │ │ │ +9E4DF   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E4E3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E4E5   Length              000B (11)
│ │ │ │ +9E4E7   Version             01 (1)
│ │ │ │ +9E4E8   UID Size            04 (4)
│ │ │ │ +9E4E9   UID                 00000000 (0)
│ │ │ │ +9E4ED   GID Size            04 (4)
│ │ │ │ +9E4EE   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E4F2 CENTRAL HEADER #26    02014B50 (33639248)
│ │ │ │ +9E4F6 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E4F7 Created OS            03 (3) 'Unix'
│ │ │ │ +9E4F8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E4F9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E4FA General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E4FC Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E4FE Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E502 CRC                   7FAE09B6 (2142112182)
│ │ │ │ +9E506 Compressed Size       00000AD1 (2769)
│ │ │ │ +9E50A Uncompressed Size     00002135 (8501)
│ │ │ │ +9E50E Filename Length       0011 (17)
│ │ │ │ +9E510 Extra Length          0018 (24)
│ │ │ │ +9E512 Comment Length        0000 (0)
│ │ │ │ +9E514 Disk Start            0000 (0)
│ │ │ │ +9E516 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E518 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E51C Local Header Offset   00035BD9 (220121)
│ │ │ │ +9E520 Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E520: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E531 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E533   Length              0005 (5)
│ │ │ │ +9E535   Flags               01 (1) 'Modification'
│ │ │ │ +9E536   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E53A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E53C   Length              000B (11)
│ │ │ │ +9E53E   Version             01 (1)
│ │ │ │ +9E53F   UID Size            04 (4)
│ │ │ │ +9E540   UID                 00000000 (0)
│ │ │ │ +9E544   GID Size            04 (4)
│ │ │ │ +9E545   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E549 CENTRAL HEADER #27    02014B50 (33639248)
│ │ │ │ +9E54D Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E54E Created OS            03 (3) 'Unix'
│ │ │ │ +9E54F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E550 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E551 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E553 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E555 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E559 CRC                   4CCDDBC1 (1288559553)
│ │ │ │ +9E55D Compressed Size       000003FE (1022)
│ │ │ │ +9E561 Uncompressed Size     00000E99 (3737)
│ │ │ │ +9E565 Filename Length       0014 (20)
│ │ │ │ +9E567 Extra Length          0018 (24)
│ │ │ │ +9E569 Comment Length        0000 (0)
│ │ │ │ +9E56B Disk Start            0000 (0)
│ │ │ │ +9E56D Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E56F Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E573 Local Header Offset   000366F5 (222965)
│ │ │ │ +9E577 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E577: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E58B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E58D   Length              0005 (5)
│ │ │ │ +9E58F   Flags               01 (1) 'Modification'
│ │ │ │ +9E590   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E594 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E596   Length              000B (11)
│ │ │ │ +9E598   Version             01 (1)
│ │ │ │ +9E599   UID Size            04 (4)
│ │ │ │ +9E59A   UID                 00000000 (0)
│ │ │ │ +9E59E   GID Size            04 (4)
│ │ │ │ +9E59F   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E5A3 CENTRAL HEADER #28    02014B50 (33639248)
│ │ │ │ +9E5A7 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E5A8 Created OS            03 (3) 'Unix'
│ │ │ │ +9E5A9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E5AA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E5AB General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E5AD Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E5AF Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E5B3 CRC                   EB83ACB7 (3951275191)
│ │ │ │ +9E5B7 Compressed Size       00001261 (4705)
│ │ │ │ +9E5BB Uncompressed Size     00003469 (13417)
│ │ │ │ +9E5BF Filename Length       0014 (20)
│ │ │ │ +9E5C1 Extra Length          0018 (24)
│ │ │ │ +9E5C3 Comment Length        0000 (0)
│ │ │ │ +9E5C5 Disk Start            0000 (0)
│ │ │ │ +9E5C7 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E5C9 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E5CD Local Header Offset   00036B41 (224065)
│ │ │ │ +9E5D1 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E5D1: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E5E5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E5E7   Length              0005 (5)
│ │ │ │ +9E5E9   Flags               01 (1) 'Modification'
│ │ │ │ +9E5EA   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E5EE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E5F0   Length              000B (11)
│ │ │ │ +9E5F2   Version             01 (1)
│ │ │ │ +9E5F3   UID Size            04 (4)
│ │ │ │ +9E5F4   UID                 00000000 (0)
│ │ │ │ +9E5F8   GID Size            04 (4)
│ │ │ │ +9E5F9   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E5FD CENTRAL HEADER #29    02014B50 (33639248)
│ │ │ │ +9E601 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E602 Created OS            03 (3) 'Unix'
│ │ │ │ +9E603 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E604 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E605 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E607 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E609 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E60D CRC                   95A9A82D (2510923821)
│ │ │ │ +9E611 Compressed Size       00000ACF (2767)
│ │ │ │ +9E615 Uncompressed Size     000022FF (8959)
│ │ │ │ +9E619 Filename Length       001B (27)
│ │ │ │ +9E61B Extra Length          0018 (24)
│ │ │ │ +9E61D Comment Length        0000 (0)
│ │ │ │ +9E61F Disk Start            0000 (0)
│ │ │ │ +9E621 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E623 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E627 Local Header Offset   00037DF0 (228848)
│ │ │ │ +9E62B Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E62B: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E646 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E648   Length              0005 (5)
│ │ │ │ +9E64A   Flags               01 (1) 'Modification'
│ │ │ │ +9E64B   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E64F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E651   Length              000B (11)
│ │ │ │ +9E653   Version             01 (1)
│ │ │ │ +9E654   UID Size            04 (4)
│ │ │ │ +9E655   UID                 00000000 (0)
│ │ │ │ +9E659   GID Size            04 (4)
│ │ │ │ +9E65A   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E65E CENTRAL HEADER #30    02014B50 (33639248)
│ │ │ │ +9E662 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E663 Created OS            03 (3) 'Unix'
│ │ │ │ +9E664 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E665 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E666 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E668 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E66A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E66E CRC                   160B7E11 (369851921)
│ │ │ │ +9E672 Compressed Size       00000A8F (2703)
│ │ │ │ +9E676 Uncompressed Size     0000237A (9082)
│ │ │ │ +9E67A Filename Length       0013 (19)
│ │ │ │ +9E67C Extra Length          0018 (24)
│ │ │ │ +9E67E Comment Length        0000 (0)
│ │ │ │ +9E680 Disk Start            0000 (0)
│ │ │ │ +9E682 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E684 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E688 Local Header Offset   00038914 (231700)
│ │ │ │ +9E68C Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E68C: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E69F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E6A1   Length              0005 (5)
│ │ │ │ +9E6A3   Flags               01 (1) 'Modification'
│ │ │ │ +9E6A4   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E6A8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E6AA   Length              000B (11)
│ │ │ │ +9E6AC   Version             01 (1)
│ │ │ │ +9E6AD   UID Size            04 (4)
│ │ │ │ +9E6AE   UID                 00000000 (0)
│ │ │ │ +9E6B2   GID Size            04 (4)
│ │ │ │ +9E6B3   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E6B7 CENTRAL HEADER #31    02014B50 (33639248)
│ │ │ │ +9E6BB Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E6BC Created OS            03 (3) 'Unix'
│ │ │ │ +9E6BD Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E6BE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E6BF General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E6C1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E6C3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E6C7 CRC                   813C96AD (2168231597)
│ │ │ │ +9E6CB Compressed Size       00000F45 (3909)
│ │ │ │ +9E6CF Uncompressed Size     000036F1 (14065)
│ │ │ │ +9E6D3 Filename Length       000F (15)
│ │ │ │ +9E6D5 Extra Length          0018 (24)
│ │ │ │ +9E6D7 Comment Length        0000 (0)
│ │ │ │ +9E6D9 Disk Start            0000 (0)
│ │ │ │ +9E6DB Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E6DD Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E6E1 Local Header Offset   000393F0 (234480)
│ │ │ │ +9E6E5 Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E6E5: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E6F4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E6F6   Length              0005 (5)
│ │ │ │ +9E6F8   Flags               01 (1) 'Modification'
│ │ │ │ +9E6F9   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E6FD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E6FF   Length              000B (11)
│ │ │ │ +9E701   Version             01 (1)
│ │ │ │ +9E702   UID Size            04 (4)
│ │ │ │ +9E703   UID                 00000000 (0)
│ │ │ │ +9E707   GID Size            04 (4)
│ │ │ │ +9E708   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E70C CENTRAL HEADER #32    02014B50 (33639248)
│ │ │ │ +9E710 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E711 Created OS            03 (3) 'Unix'
│ │ │ │ +9E712 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E713 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E714 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E716 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E718 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E71C CRC                   54672E6E (1416048238)
│ │ │ │ +9E720 Compressed Size       0000066A (1642)
│ │ │ │ +9E724 Uncompressed Size     000018DF (6367)
│ │ │ │ +9E728 Filename Length       000F (15)
│ │ │ │ +9E72A Extra Length          0018 (24)
│ │ │ │ +9E72C Comment Length        0000 (0)
│ │ │ │ +9E72E Disk Start            0000 (0)
│ │ │ │ +9E730 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E732 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E736 Local Header Offset   0003A37E (238462)
│ │ │ │ +9E73A Filename              'XXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E73A: Filename 'XXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E749 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E74B   Length              0005 (5)
│ │ │ │ +9E74D   Flags               01 (1) 'Modification'
│ │ │ │ +9E74E   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E752 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E754   Length              000B (11)
│ │ │ │ +9E756   Version             01 (1)
│ │ │ │ +9E757   UID Size            04 (4)
│ │ │ │ +9E758   UID                 00000000 (0)
│ │ │ │ +9E75C   GID Size            04 (4)
│ │ │ │ +9E75D   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E761 CENTRAL HEADER #33    02014B50 (33639248)
│ │ │ │ +9E765 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E766 Created OS            03 (3) 'Unix'
│ │ │ │ +9E767 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E768 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E769 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E76B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E76D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E771 CRC                   71733BC2 (1903377346)
│ │ │ │ +9E775 Compressed Size       00001A48 (6728)
│ │ │ │ +9E779 Uncompressed Size     000064F2 (25842)
│ │ │ │ +9E77D Filename Length       0013 (19)
│ │ │ │ +9E77F Extra Length          0018 (24)
│ │ │ │ +9E781 Comment Length        0000 (0)
│ │ │ │ +9E783 Disk Start            0000 (0)
│ │ │ │ +9E785 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E787 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E78B Local Header Offset   0003AA31 (240177)
│ │ │ │ +9E78F Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E78F: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E7A2 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E7A4   Length              0005 (5)
│ │ │ │ +9E7A6   Flags               01 (1) 'Modification'
│ │ │ │ +9E7A7   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E7AB Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E7AD   Length              000B (11)
│ │ │ │ +9E7AF   Version             01 (1)
│ │ │ │ +9E7B0   UID Size            04 (4)
│ │ │ │ +9E7B1   UID                 00000000 (0)
│ │ │ │ +9E7B5   GID Size            04 (4)
│ │ │ │ +9E7B6   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E7BA CENTRAL HEADER #34    02014B50 (33639248)
│ │ │ │ +9E7BE Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E7BF Created OS            03 (3) 'Unix'
│ │ │ │ +9E7C0 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E7C1 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E7C2 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E7C4 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E7C6 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E7CA CRC                   D1448544 (3510928708)
│ │ │ │ +9E7CE Compressed Size       000009A5 (2469)
│ │ │ │ +9E7D2 Uncompressed Size     00001B64 (7012)
│ │ │ │ +9E7D6 Filename Length       0010 (16)
│ │ │ │ +9E7D8 Extra Length          0018 (24)
│ │ │ │ +9E7DA Comment Length        0000 (0)
│ │ │ │ +9E7DC Disk Start            0000 (0)
│ │ │ │ +9E7DE Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E7E0 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E7E4 Local Header Offset   0003C4C6 (246982)
│ │ │ │ +9E7E8 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E7E8: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E7F8 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E7FA   Length              0005 (5)
│ │ │ │ +9E7FC   Flags               01 (1) 'Modification'
│ │ │ │ +9E7FD   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E801 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E803   Length              000B (11)
│ │ │ │ +9E805   Version             01 (1)
│ │ │ │ +9E806   UID Size            04 (4)
│ │ │ │ +9E807   UID                 00000000 (0)
│ │ │ │ +9E80B   GID Size            04 (4)
│ │ │ │ +9E80C   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E810 CENTRAL HEADER #35    02014B50 (33639248)
│ │ │ │ +9E814 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E815 Created OS            03 (3) 'Unix'
│ │ │ │ +9E816 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E817 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E818 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E81A Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E81C Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E820 CRC                   3E5AEB62 (1046145890)
│ │ │ │ +9E824 Compressed Size       000006B7 (1719)
│ │ │ │ +9E828 Uncompressed Size     00001565 (5477)
│ │ │ │ +9E82C Filename Length       0012 (18)
│ │ │ │ +9E82E Extra Length          0018 (24)
│ │ │ │ +9E830 Comment Length        0000 (0)
│ │ │ │ +9E832 Disk Start            0000 (0)
│ │ │ │ +9E834 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E836 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E83A Local Header Offset   0003CEB5 (249525)
│ │ │ │ +9E83E Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E83E: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E850 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E852   Length              0005 (5)
│ │ │ │ +9E854   Flags               01 (1) 'Modification'
│ │ │ │ +9E855   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E859 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E85B   Length              000B (11)
│ │ │ │ +9E85D   Version             01 (1)
│ │ │ │ +9E85E   UID Size            04 (4)
│ │ │ │ +9E85F   UID                 00000000 (0)
│ │ │ │ +9E863   GID Size            04 (4)
│ │ │ │ +9E864   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E868 CENTRAL HEADER #36    02014B50 (33639248)
│ │ │ │ +9E86C Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E86D Created OS            03 (3) 'Unix'
│ │ │ │ +9E86E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E86F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E870 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E872 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E874 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E878 CRC                   0CAC5654 (212620884)
│ │ │ │ +9E87C Compressed Size       00002A18 (10776)
│ │ │ │ +9E880 Uncompressed Size     0000B1C5 (45509)
│ │ │ │ +9E884 Filename Length       0010 (16)
│ │ │ │ +9E886 Extra Length          0018 (24)
│ │ │ │ +9E888 Comment Length        0000 (0)
│ │ │ │ +9E88A Disk Start            0000 (0)
│ │ │ │ +9E88C Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E88E Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E892 Local Header Offset   0003D5B8 (251320)
│ │ │ │ +9E896 Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E896: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E8A6 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E8A8   Length              0005 (5)
│ │ │ │ +9E8AA   Flags               01 (1) 'Modification'
│ │ │ │ +9E8AB   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E8AF Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E8B1   Length              000B (11)
│ │ │ │ +9E8B3   Version             01 (1)
│ │ │ │ +9E8B4   UID Size            04 (4)
│ │ │ │ +9E8B5   UID                 00000000 (0)
│ │ │ │ +9E8B9   GID Size            04 (4)
│ │ │ │ +9E8BA   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E8BE CENTRAL HEADER #37    02014B50 (33639248)
│ │ │ │ +9E8C2 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E8C3 Created OS            03 (3) 'Unix'
│ │ │ │ +9E8C4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E8C5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E8C6 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E8C8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E8CA Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E8CE CRC                   7F12A43C (2131928124)
│ │ │ │ +9E8D2 Compressed Size       00001E82 (7810)
│ │ │ │ +9E8D6 Uncompressed Size     00009AAA (39594)
│ │ │ │ +9E8DA Filename Length       0012 (18)
│ │ │ │ +9E8DC Extra Length          0018 (24)
│ │ │ │ +9E8DE Comment Length        0000 (0)
│ │ │ │ +9E8E0 Disk Start            0000 (0)
│ │ │ │ +9E8E2 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E8E4 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E8E8 Local Header Offset   0004001A (262170)
│ │ │ │ +9E8EC Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E8EC: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E8FE Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E900   Length              0005 (5)
│ │ │ │ +9E902   Flags               01 (1) 'Modification'
│ │ │ │ +9E903   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E907 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E909   Length              000B (11)
│ │ │ │ +9E90B   Version             01 (1)
│ │ │ │ +9E90C   UID Size            04 (4)
│ │ │ │ +9E90D   UID                 00000000 (0)
│ │ │ │ +9E911   GID Size            04 (4)
│ │ │ │ +9E912   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E916 CENTRAL HEADER #38    02014B50 (33639248)
│ │ │ │ +9E91A Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E91B Created OS            03 (3) 'Unix'
│ │ │ │ +9E91C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E91D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E91E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E920 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E922 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E926 CRC                   E63D084C (3862759500)
│ │ │ │ +9E92A Compressed Size       00001474 (5236)
│ │ │ │ +9E92E Uncompressed Size     00007ACF (31439)
│ │ │ │ +9E932 Filename Length       0018 (24)
│ │ │ │ +9E934 Extra Length          0018 (24)
│ │ │ │ +9E936 Comment Length        0000 (0)
│ │ │ │ +9E938 Disk Start            0000 (0)
│ │ │ │ +9E93A Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E93C Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E940 Local Header Offset   00041EE8 (270056)
│ │ │ │ +9E944 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E944: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E95C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E95E   Length              0005 (5)
│ │ │ │ +9E960   Flags               01 (1) 'Modification'
│ │ │ │ +9E961   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E965 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E967   Length              000B (11)
│ │ │ │ +9E969   Version             01 (1)
│ │ │ │ +9E96A   UID Size            04 (4)
│ │ │ │ +9E96B   UID                 00000000 (0)
│ │ │ │ +9E96F   GID Size            04 (4)
│ │ │ │ +9E970   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E974 CENTRAL HEADER #39    02014B50 (33639248)
│ │ │ │ +9E978 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E979 Created OS            03 (3) 'Unix'
│ │ │ │ +9E97A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E97B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E97C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E97E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E980 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E984 CRC                   2F887888 (797472904)
│ │ │ │ +9E988 Compressed Size       000018CB (6347)
│ │ │ │ +9E98C Uncompressed Size     0000A7F4 (42996)
│ │ │ │ +9E990 Filename Length       001F (31)
│ │ │ │ +9E992 Extra Length          0018 (24)
│ │ │ │ +9E994 Comment Length        0000 (0)
│ │ │ │ +9E996 Disk Start            0000 (0)
│ │ │ │ +9E998 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E99A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9E99E Local Header Offset   000433AE (275374)
│ │ │ │ +9E9A2 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9E9A2: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9E9C1 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9E9C3   Length              0005 (5)
│ │ │ │ +9E9C5   Flags               01 (1) 'Modification'
│ │ │ │ +9E9C6   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E9CA Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9E9CC   Length              000B (11)
│ │ │ │ +9E9CE   Version             01 (1)
│ │ │ │ +9E9CF   UID Size            04 (4)
│ │ │ │ +9E9D0   UID                 00000000 (0)
│ │ │ │ +9E9D4   GID Size            04 (4)
│ │ │ │ +9E9D5   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9E9D9 CENTRAL HEADER #40    02014B50 (33639248)
│ │ │ │ +9E9DD Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9E9DE Created OS            03 (3) 'Unix'
│ │ │ │ +9E9DF Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9E9E0 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9E9E1 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9E9E3 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9E9E5 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9E9E9 CRC                   FFAF198F (4289665423)
│ │ │ │ +9E9ED Compressed Size       000003F6 (1014)
│ │ │ │ +9E9F1 Uncompressed Size     000008A3 (2211)
│ │ │ │ +9E9F5 Filename Length       001E (30)
│ │ │ │ +9E9F7 Extra Length          0018 (24)
│ │ │ │ +9E9F9 Comment Length        0000 (0)
│ │ │ │ +9E9FB Disk Start            0000 (0)
│ │ │ │ +9E9FD Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9E9FF Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EA03 Local Header Offset   00044CD2 (281810)
│ │ │ │ +9EA07 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EA07: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EA25 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EA27   Length              0005 (5)
│ │ │ │ +9EA29   Flags               01 (1) 'Modification'
│ │ │ │ +9EA2A   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EA2E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EA30   Length              000B (11)
│ │ │ │ +9EA32   Version             01 (1)
│ │ │ │ +9EA33   UID Size            04 (4)
│ │ │ │ +9EA34   UID                 00000000 (0)
│ │ │ │ +9EA38   GID Size            04 (4)
│ │ │ │ +9EA39   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EA3D CENTRAL HEADER #41    02014B50 (33639248)
│ │ │ │ +9EA41 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EA42 Created OS            03 (3) 'Unix'
│ │ │ │ +9EA43 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EA44 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EA45 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EA47 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EA49 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EA4D CRC                   32E3FA13 (853801491)
│ │ │ │ +9EA51 Compressed Size       00004292 (17042)
│ │ │ │ +9EA55 Uncompressed Size     0000D8DC (55516)
│ │ │ │ +9EA59 Filename Length       0013 (19)
│ │ │ │ +9EA5B Extra Length          0018 (24)
│ │ │ │ +9EA5D Comment Length        0000 (0)
│ │ │ │ +9EA5F Disk Start            0000 (0)
│ │ │ │ +9EA61 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EA63 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EA67 Local Header Offset   00045120 (282912)
│ │ │ │ +9EA6B Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EA6B: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EA7E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EA80   Length              0005 (5)
│ │ │ │ +9EA82   Flags               01 (1) 'Modification'
│ │ │ │ +9EA83   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EA87 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EA89   Length              000B (11)
│ │ │ │ +9EA8B   Version             01 (1)
│ │ │ │ +9EA8C   UID Size            04 (4)
│ │ │ │ +9EA8D   UID                 00000000 (0)
│ │ │ │ +9EA91   GID Size            04 (4)
│ │ │ │ +9EA92   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EA96 CENTRAL HEADER #42    02014B50 (33639248)
│ │ │ │ +9EA9A Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EA9B Created OS            03 (3) 'Unix'
│ │ │ │ +9EA9C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EA9D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EA9E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EAA0 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EAA2 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EAA6 CRC                   0AAA7D81 (178945409)
│ │ │ │ +9EAAA Compressed Size       000026C5 (9925)
│ │ │ │ +9EAAE Uncompressed Size     00006E45 (28229)
│ │ │ │ +9EAB2 Filename Length       0019 (25)
│ │ │ │ +9EAB4 Extra Length          0018 (24)
│ │ │ │ +9EAB6 Comment Length        0000 (0)
│ │ │ │ +9EAB8 Disk Start            0000 (0)
│ │ │ │ +9EABA Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EABC Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EAC0 Local Header Offset   000493FF (300031)
│ │ │ │ +9EAC4 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EAC4: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EADD Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EADF   Length              0005 (5)
│ │ │ │ +9EAE1   Flags               01 (1) 'Modification'
│ │ │ │ +9EAE2   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EAE6 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EAE8   Length              000B (11)
│ │ │ │ +9EAEA   Version             01 (1)
│ │ │ │ +9EAEB   UID Size            04 (4)
│ │ │ │ +9EAEC   UID                 00000000 (0)
│ │ │ │ +9EAF0   GID Size            04 (4)
│ │ │ │ +9EAF1   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EAF5 CENTRAL HEADER #43    02014B50 (33639248)
│ │ │ │ +9EAF9 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EAFA Created OS            03 (3) 'Unix'
│ │ │ │ +9EAFB Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EAFC Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EAFD General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EAFF Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EB01 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EB05 CRC                   0369577C (57235324)
│ │ │ │ +9EB09 Compressed Size       00002739 (10041)
│ │ │ │ +9EB0D Uncompressed Size     00008B83 (35715)
│ │ │ │ +9EB11 Filename Length       0019 (25)
│ │ │ │ +9EB13 Extra Length          0018 (24)
│ │ │ │ +9EB15 Comment Length        0000 (0)
│ │ │ │ +9EB17 Disk Start            0000 (0)
│ │ │ │ +9EB19 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EB1B Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EB1F Local Header Offset   0004BB17 (310039)
│ │ │ │ +9EB23 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EB23: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EB3C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EB3E   Length              0005 (5)
│ │ │ │ +9EB40   Flags               01 (1) 'Modification'
│ │ │ │ +9EB41   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EB45 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EB47   Length              000B (11)
│ │ │ │ +9EB49   Version             01 (1)
│ │ │ │ +9EB4A   UID Size            04 (4)
│ │ │ │ +9EB4B   UID                 00000000 (0)
│ │ │ │ +9EB4F   GID Size            04 (4)
│ │ │ │ +9EB50   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EB54 CENTRAL HEADER #44    02014B50 (33639248)
│ │ │ │ +9EB58 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EB59 Created OS            03 (3) 'Unix'
│ │ │ │ +9EB5A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EB5B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EB5C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EB5E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EB60 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EB64 CRC                   6DB8C629 (1840825897)
│ │ │ │ +9EB68 Compressed Size       00000CF2 (3314)
│ │ │ │ +9EB6C Uncompressed Size     0000517A (20858)
│ │ │ │ +9EB70 Filename Length       0021 (33)
│ │ │ │ +9EB72 Extra Length          0018 (24)
│ │ │ │ +9EB74 Comment Length        0000 (0)
│ │ │ │ +9EB76 Disk Start            0000 (0)
│ │ │ │ +9EB78 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EB7A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EB7E Local Header Offset   0004E2A3 (320163)
│ │ │ │ +9EB82 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EB82: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EBA3 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EBA5   Length              0005 (5)
│ │ │ │ +9EBA7   Flags               01 (1) 'Modification'
│ │ │ │ +9EBA8   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EBAC Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EBAE   Length              000B (11)
│ │ │ │ +9EBB0   Version             01 (1)
│ │ │ │ +9EBB1   UID Size            04 (4)
│ │ │ │ +9EBB2   UID                 00000000 (0)
│ │ │ │ +9EBB6   GID Size            04 (4)
│ │ │ │ +9EBB7   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EBBB CENTRAL HEADER #45    02014B50 (33639248)
│ │ │ │ +9EBBF Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EBC0 Created OS            03 (3) 'Unix'
│ │ │ │ +9EBC1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EBC2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EBC3 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EBC5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EBC7 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EBCB CRC                   8F01E69C (2399266460)
│ │ │ │ +9EBCF Compressed Size       00000468 (1128)
│ │ │ │ +9EBD3 Uncompressed Size     00000931 (2353)
│ │ │ │ +9EBD7 Filename Length       001B (27)
│ │ │ │ +9EBD9 Extra Length          0018 (24)
│ │ │ │ +9EBDB Comment Length        0000 (0)
│ │ │ │ +9EBDD Disk Start            0000 (0)
│ │ │ │ +9EBDF Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EBE1 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EBE5 Local Header Offset   0004EFF0 (323568)
│ │ │ │ +9EBE9 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EBE9: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EC04 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EC06   Length              0005 (5)
│ │ │ │ +9EC08   Flags               01 (1) 'Modification'
│ │ │ │ +9EC09   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EC0D Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EC0F   Length              000B (11)
│ │ │ │ +9EC11   Version             01 (1)
│ │ │ │ +9EC12   UID Size            04 (4)
│ │ │ │ +9EC13   UID                 00000000 (0)
│ │ │ │ +9EC17   GID Size            04 (4)
│ │ │ │ +9EC18   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EC1C CENTRAL HEADER #46    02014B50 (33639248)
│ │ │ │ +9EC20 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EC21 Created OS            03 (3) 'Unix'
│ │ │ │ +9EC22 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EC23 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EC24 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EC26 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EC28 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EC2C CRC                   0D0600BA (218497210)
│ │ │ │ +9EC30 Compressed Size       000016EF (5871)
│ │ │ │ +9EC34 Uncompressed Size     00007A6D (31341)
│ │ │ │ +9EC38 Filename Length       001F (31)
│ │ │ │ +9EC3A Extra Length          0018 (24)
│ │ │ │ +9EC3C Comment Length        0000 (0)
│ │ │ │ +9EC3E Disk Start            0000 (0)
│ │ │ │ +9EC40 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EC42 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EC46 Local Header Offset   0004F4AD (324781)
│ │ │ │ +9EC4A Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EC4A: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EC69 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EC6B   Length              0005 (5)
│ │ │ │ +9EC6D   Flags               01 (1) 'Modification'
│ │ │ │ +9EC6E   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EC72 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EC74   Length              000B (11)
│ │ │ │ +9EC76   Version             01 (1)
│ │ │ │ +9EC77   UID Size            04 (4)
│ │ │ │ +9EC78   UID                 00000000 (0)
│ │ │ │ +9EC7C   GID Size            04 (4)
│ │ │ │ +9EC7D   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EC81 CENTRAL HEADER #47    02014B50 (33639248)
│ │ │ │ +9EC85 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EC86 Created OS            03 (3) 'Unix'
│ │ │ │ +9EC87 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EC88 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EC89 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EC8B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EC8D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EC91 CRC                   F6942733 (4136904499)
│ │ │ │ +9EC95 Compressed Size       00004177 (16759)
│ │ │ │ +9EC99 Uncompressed Size     0001CF93 (118675)
│ │ │ │ +9EC9D Filename Length       0010 (16)
│ │ │ │ +9EC9F Extra Length          0018 (24)
│ │ │ │ +9ECA1 Comment Length        0000 (0)
│ │ │ │ +9ECA3 Disk Start            0000 (0)
│ │ │ │ +9ECA5 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9ECA7 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9ECAB Local Header Offset   00050BF5 (330741)
│ │ │ │ +9ECAF Filename              'XXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9ECAF: Filename 'XXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9ECBF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9ECC1   Length              0005 (5)
│ │ │ │ +9ECC3   Flags               01 (1) 'Modification'
│ │ │ │ +9ECC4   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9ECC8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9ECCA   Length              000B (11)
│ │ │ │ +9ECCC   Version             01 (1)
│ │ │ │ +9ECCD   UID Size            04 (4)
│ │ │ │ +9ECCE   UID                 00000000 (0)
│ │ │ │ +9ECD2   GID Size            04 (4)
│ │ │ │ +9ECD3   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9ECD7 CENTRAL HEADER #48    02014B50 (33639248)
│ │ │ │ +9ECDB Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9ECDC Created OS            03 (3) 'Unix'
│ │ │ │ +9ECDD Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9ECDE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9ECDF General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9ECE1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9ECE3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9ECE7 CRC                   2020DAF6 (539024118)
│ │ │ │ +9ECEB Compressed Size       00000A94 (2708)
│ │ │ │ +9ECEF Uncompressed Size     00002105 (8453)
│ │ │ │ +9ECF3 Filename Length       0014 (20)
│ │ │ │ +9ECF5 Extra Length          0018 (24)
│ │ │ │ +9ECF7 Comment Length        0000 (0)
│ │ │ │ +9ECF9 Disk Start            0000 (0)
│ │ │ │ +9ECFB Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9ECFD Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9ED01 Local Header Offset   00054DB6 (347574)
│ │ │ │ +9ED05 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9ED05: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9ED19 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9ED1B   Length              0005 (5)
│ │ │ │ +9ED1D   Flags               01 (1) 'Modification'
│ │ │ │ +9ED1E   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9ED22 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9ED24   Length              000B (11)
│ │ │ │ +9ED26   Version             01 (1)
│ │ │ │ +9ED27   UID Size            04 (4)
│ │ │ │ +9ED28   UID                 00000000 (0)
│ │ │ │ +9ED2C   GID Size            04 (4)
│ │ │ │ +9ED2D   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9ED31 CENTRAL HEADER #49    02014B50 (33639248)
│ │ │ │ +9ED35 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9ED36 Created OS            03 (3) 'Unix'
│ │ │ │ +9ED37 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9ED38 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9ED39 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9ED3B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9ED3D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9ED41 CRC                   B73364B1 (3073598641)
│ │ │ │ +9ED45 Compressed Size       0000ACA6 (44198)
│ │ │ │ +9ED49 Uncompressed Size     0003E418 (255000)
│ │ │ │ +9ED4D Filename Length       0017 (23)
│ │ │ │ +9ED4F Extra Length          0018 (24)
│ │ │ │ +9ED51 Comment Length        0000 (0)
│ │ │ │ +9ED53 Disk Start            0000 (0)
│ │ │ │ +9ED55 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9ED57 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9ED5B Local Header Offset   00055898 (350360)
│ │ │ │ +9ED5F Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9ED5F: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9ED76 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9ED78   Length              0005 (5)
│ │ │ │ +9ED7A   Flags               01 (1) 'Modification'
│ │ │ │ +9ED7B   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9ED7F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9ED81   Length              000B (11)
│ │ │ │ +9ED83   Version             01 (1)
│ │ │ │ +9ED84   UID Size            04 (4)
│ │ │ │ +9ED85   UID                 00000000 (0)
│ │ │ │ +9ED89   GID Size            04 (4)
│ │ │ │ +9ED8A   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9ED8E CENTRAL HEADER #50    02014B50 (33639248)
│ │ │ │ +9ED92 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9ED93 Created OS            03 (3) 'Unix'
│ │ │ │ +9ED94 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9ED95 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9ED96 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9ED98 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9ED9A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9ED9E CRC                   102FB47C (271561852)
│ │ │ │ +9EDA2 Compressed Size       00000401 (1025)
│ │ │ │ +9EDA6 Uncompressed Size     0000093D (2365)
│ │ │ │ +9EDAA Filename Length       0013 (19)
│ │ │ │ +9EDAC Extra Length          0018 (24)
│ │ │ │ +9EDAE Comment Length        0000 (0)
│ │ │ │ +9EDB0 Disk Start            0000 (0)
│ │ │ │ +9EDB2 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EDB4 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EDB8 Local Header Offset   0006058F (394639)
│ │ │ │ +9EDBC Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EDBC: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EDCF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EDD1   Length              0005 (5)
│ │ │ │ +9EDD3   Flags               01 (1) 'Modification'
│ │ │ │ +9EDD4   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EDD8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EDDA   Length              000B (11)
│ │ │ │ +9EDDC   Version             01 (1)
│ │ │ │ +9EDDD   UID Size            04 (4)
│ │ │ │ +9EDDE   UID                 00000000 (0)
│ │ │ │ +9EDE2   GID Size            04 (4)
│ │ │ │ +9EDE3   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EDE7 CENTRAL HEADER #51    02014B50 (33639248)
│ │ │ │ +9EDEB Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EDEC Created OS            03 (3) 'Unix'
│ │ │ │ +9EDED Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EDEE Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EDEF General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EDF1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EDF3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EDF7 CRC                   B3F70F09 (3019312905)
│ │ │ │ +9EDFB Compressed Size       000014E4 (5348)
│ │ │ │ +9EDFF Uncompressed Size     0000687B (26747)
│ │ │ │ +9EE03 Filename Length       0012 (18)
│ │ │ │ +9EE05 Extra Length          0018 (24)
│ │ │ │ +9EE07 Comment Length        0000 (0)
│ │ │ │ +9EE09 Disk Start            0000 (0)
│ │ │ │ +9EE0B Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EE0D Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EE11 Local Header Offset   000609DD (395741)
│ │ │ │ +9EE15 Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EE15: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EE27 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EE29   Length              0005 (5)
│ │ │ │ +9EE2B   Flags               01 (1) 'Modification'
│ │ │ │ +9EE2C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EE30 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EE32   Length              000B (11)
│ │ │ │ +9EE34   Version             01 (1)
│ │ │ │ +9EE35   UID Size            04 (4)
│ │ │ │ +9EE36   UID                 00000000 (0)
│ │ │ │ +9EE3A   GID Size            04 (4)
│ │ │ │ +9EE3B   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EE3F CENTRAL HEADER #52    02014B50 (33639248)
│ │ │ │ +9EE43 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EE44 Created OS            03 (3) 'Unix'
│ │ │ │ +9EE45 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EE46 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EE47 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EE49 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EE4B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EE4F CRC                   44472F97 (1145515927)
│ │ │ │ +9EE53 Compressed Size       000011EB (4587)
│ │ │ │ +9EE57 Uncompressed Size     000040F5 (16629)
│ │ │ │ +9EE5B Filename Length       0012 (18)
│ │ │ │ +9EE5D Extra Length          0018 (24)
│ │ │ │ +9EE5F Comment Length        0000 (0)
│ │ │ │ +9EE61 Disk Start            0000 (0)
│ │ │ │ +9EE63 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EE65 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EE69 Local Header Offset   00061F0D (401165)
│ │ │ │ +9EE6D Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EE6D: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EE7F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EE81   Length              0005 (5)
│ │ │ │ +9EE83   Flags               01 (1) 'Modification'
│ │ │ │ +9EE84   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EE88 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EE8A   Length              000B (11)
│ │ │ │ +9EE8C   Version             01 (1)
│ │ │ │ +9EE8D   UID Size            04 (4)
│ │ │ │ +9EE8E   UID                 00000000 (0)
│ │ │ │ +9EE92   GID Size            04 (4)
│ │ │ │ +9EE93   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EE97 CENTRAL HEADER #53    02014B50 (33639248)
│ │ │ │ +9EE9B Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EE9C Created OS            03 (3) 'Unix'
│ │ │ │ +9EE9D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EE9E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EE9F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EEA1 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EEA3 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EEA7 CRC                   5D525827 (1565677607)
│ │ │ │ +9EEAB Compressed Size       000009DA (2522)
│ │ │ │ +9EEAF Uncompressed Size     00003529 (13609)
│ │ │ │ +9EEB3 Filename Length       0019 (25)
│ │ │ │ +9EEB5 Extra Length          0018 (24)
│ │ │ │ +9EEB7 Comment Length        0000 (0)
│ │ │ │ +9EEB9 Disk Start            0000 (0)
│ │ │ │ +9EEBB Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EEBD Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EEC1 Local Header Offset   00063144 (405828)
│ │ │ │ +9EEC5 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EEC5: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EEDE Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EEE0   Length              0005 (5)
│ │ │ │ +9EEE2   Flags               01 (1) 'Modification'
│ │ │ │ +9EEE3   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EEE7 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EEE9   Length              000B (11)
│ │ │ │ +9EEEB   Version             01 (1)
│ │ │ │ +9EEEC   UID Size            04 (4)
│ │ │ │ +9EEED   UID                 00000000 (0)
│ │ │ │ +9EEF1   GID Size            04 (4)
│ │ │ │ +9EEF2   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EEF6 CENTRAL HEADER #54    02014B50 (33639248)
│ │ │ │ +9EEFA Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EEFB Created OS            03 (3) 'Unix'
│ │ │ │ +9EEFC Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EEFD Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EEFE General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EF00 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EF02 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EF06 CRC                   9170A9FB (2440079867)
│ │ │ │ +9EF0A Compressed Size       000018B3 (6323)
│ │ │ │ +9EF0E Uncompressed Size     0000A605 (42501)
│ │ │ │ +9EF12 Filename Length       0019 (25)
│ │ │ │ +9EF14 Extra Length          0018 (24)
│ │ │ │ +9EF16 Comment Length        0000 (0)
│ │ │ │ +9EF18 Disk Start            0000 (0)
│ │ │ │ +9EF1A Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EF1C Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EF20 Local Header Offset   00063B71 (408433)
│ │ │ │ +9EF24 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EF24: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EF3D Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EF3F   Length              0005 (5)
│ │ │ │ +9EF41   Flags               01 (1) 'Modification'
│ │ │ │ +9EF42   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EF46 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EF48   Length              000B (11)
│ │ │ │ +9EF4A   Version             01 (1)
│ │ │ │ +9EF4B   UID Size            04 (4)
│ │ │ │ +9EF4C   UID                 00000000 (0)
│ │ │ │ +9EF50   GID Size            04 (4)
│ │ │ │ +9EF51   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EF55 CENTRAL HEADER #55    02014B50 (33639248)
│ │ │ │ +9EF59 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EF5A Created OS            03 (3) 'Unix'
│ │ │ │ +9EF5B Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EF5C Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EF5D General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EF5F Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EF61 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EF65 CRC                   47E0D6DC (1205917404)
│ │ │ │ +9EF69 Compressed Size       0000177E (6014)
│ │ │ │ +9EF6D Uncompressed Size     0000472C (18220)
│ │ │ │ +9EF71 Filename Length       0014 (20)
│ │ │ │ +9EF73 Extra Length          0018 (24)
│ │ │ │ +9EF75 Comment Length        0000 (0)
│ │ │ │ +9EF77 Disk Start            0000 (0)
│ │ │ │ +9EF79 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EF7B Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EF7F Local Header Offset   00065477 (414839)
│ │ │ │ +9EF83 Filename              'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EF83: Filename 'XXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EF97 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EF99   Length              0005 (5)
│ │ │ │ +9EF9B   Flags               01 (1) 'Modification'
│ │ │ │ +9EF9C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EFA0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9EFA2   Length              000B (11)
│ │ │ │ +9EFA4   Version             01 (1)
│ │ │ │ +9EFA5   UID Size            04 (4)
│ │ │ │ +9EFA6   UID                 00000000 (0)
│ │ │ │ +9EFAA   GID Size            04 (4)
│ │ │ │ +9EFAB   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9EFAF CENTRAL HEADER #56    02014B50 (33639248)
│ │ │ │ +9EFB3 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9EFB4 Created OS            03 (3) 'Unix'
│ │ │ │ +9EFB5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9EFB6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9EFB7 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9EFB9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9EFBB Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9EFBF CRC                   EDF51269 (3992261225)
│ │ │ │ +9EFC3 Compressed Size       0000040B (1035)
│ │ │ │ +9EFC7 Uncompressed Size     00000825 (2085)
│ │ │ │ +9EFCB Filename Length       001C (28)
│ │ │ │ +9EFCD Extra Length          0018 (24)
│ │ │ │ +9EFCF Comment Length        0000 (0)
│ │ │ │ +9EFD1 Disk Start            0000 (0)
│ │ │ │ +9EFD3 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9EFD5 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9EFD9 Local Header Offset   00066C43 (420931)
│ │ │ │ +9EFDD Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9EFDD: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9EFF9 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9EFFB   Length              0005 (5)
│ │ │ │ +9EFFD   Flags               01 (1) 'Modification'
│ │ │ │ +9EFFE   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F002 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F004   Length              000B (11)
│ │ │ │ +9F006   Version             01 (1)
│ │ │ │ +9F007   UID Size            04 (4)
│ │ │ │ +9F008   UID                 00000000 (0)
│ │ │ │ +9F00C   GID Size            04 (4)
│ │ │ │ +9F00D   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F011 CENTRAL HEADER #57    02014B50 (33639248)
│ │ │ │ +9F015 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F016 Created OS            03 (3) 'Unix'
│ │ │ │ +9F017 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F018 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F019 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F01B Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F01D Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F021 CRC                   3F7C9239 (1065128505)
│ │ │ │ +9F025 Compressed Size       00002480 (9344)
│ │ │ │ +9F029 Uncompressed Size     0000B56F (46447)
│ │ │ │ +9F02D Filename Length       001F (31)
│ │ │ │ +9F02F Extra Length          0018 (24)
│ │ │ │ +9F031 Comment Length        0000 (0)
│ │ │ │ +9F033 Disk Start            0000 (0)
│ │ │ │ +9F035 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F037 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F03B Local Header Offset   000670A4 (422052)
│ │ │ │ +9F03F Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F03F: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F05E Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F060   Length              0005 (5)
│ │ │ │ +9F062   Flags               01 (1) 'Modification'
│ │ │ │ +9F063   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F067 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F069   Length              000B (11)
│ │ │ │ +9F06B   Version             01 (1)
│ │ │ │ +9F06C   UID Size            04 (4)
│ │ │ │ +9F06D   UID                 00000000 (0)
│ │ │ │ +9F071   GID Size            04 (4)
│ │ │ │ +9F072   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F076 CENTRAL HEADER #58    02014B50 (33639248)
│ │ │ │ +9F07A Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F07B Created OS            03 (3) 'Unix'
│ │ │ │ +9F07C Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F07D Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F07E General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F080 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F082 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F086 CRC                   870D678F (2265802639)
│ │ │ │ +9F08A Compressed Size       00000E7D (3709)
│ │ │ │ +9F08E Uncompressed Size     000052D9 (21209)
│ │ │ │ +9F092 Filename Length       001F (31)
│ │ │ │ +9F094 Extra Length          0018 (24)
│ │ │ │ +9F096 Comment Length        0000 (0)
│ │ │ │ +9F098 Disk Start            0000 (0)
│ │ │ │ +9F09A Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F09C Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F0A0 Local Header Offset   0006957D (431485)
│ │ │ │ +9F0A4 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F0A4: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F0C3 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F0C5   Length              0005 (5)
│ │ │ │ +9F0C7   Flags               01 (1) 'Modification'
│ │ │ │ +9F0C8   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F0CC Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F0CE   Length              000B (11)
│ │ │ │ +9F0D0   Version             01 (1)
│ │ │ │ +9F0D1   UID Size            04 (4)
│ │ │ │ +9F0D2   UID                 00000000 (0)
│ │ │ │ +9F0D6   GID Size            04 (4)
│ │ │ │ +9F0D7   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F0DB CENTRAL HEADER #59    02014B50 (33639248)
│ │ │ │ +9F0DF Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F0E0 Created OS            03 (3) 'Unix'
│ │ │ │ +9F0E1 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F0E2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F0E3 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F0E5 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F0E7 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F0EB CRC                   862D2937 (2251106615)
│ │ │ │ +9F0EF Compressed Size       00000A44 (2628)
│ │ │ │ +9F0F3 Uncompressed Size     0000247A (9338)
│ │ │ │ +9F0F7 Filename Length       0013 (19)
│ │ │ │ +9F0F9 Extra Length          0018 (24)
│ │ │ │ +9F0FB Comment Length        0000 (0)
│ │ │ │ +9F0FD Disk Start            0000 (0)
│ │ │ │ +9F0FF Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F101 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F105 Local Header Offset   0006A453 (435283)
│ │ │ │ +9F109 Filename              'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F109: Filename 'XXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F11C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F11E   Length              0005 (5)
│ │ │ │ +9F120   Flags               01 (1) 'Modification'
│ │ │ │ +9F121   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F125 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F127   Length              000B (11)
│ │ │ │ +9F129   Version             01 (1)
│ │ │ │ +9F12A   UID Size            04 (4)
│ │ │ │ +9F12B   UID                 00000000 (0)
│ │ │ │ +9F12F   GID Size            04 (4)
│ │ │ │ +9F130   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F134 CENTRAL HEADER #60    02014B50 (33639248)
│ │ │ │ +9F138 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F139 Created OS            03 (3) 'Unix'
│ │ │ │ +9F13A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F13B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F13C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F13E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F140 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F144 CRC                   EB0E516C (3943584108)
│ │ │ │ +9F148 Compressed Size       00002489 (9353)
│ │ │ │ +9F14C Uncompressed Size     0000B84C (47180)
│ │ │ │ +9F150 Filename Length       0019 (25)
│ │ │ │ +9F152 Extra Length          0018 (24)
│ │ │ │ +9F154 Comment Length        0000 (0)
│ │ │ │ +9F156 Disk Start            0000 (0)
│ │ │ │ +9F158 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F15A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F15E Local Header Offset   0006AEE4 (437988)
│ │ │ │ +9F162 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F162: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F17B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F17D   Length              0005 (5)
│ │ │ │ +9F17F   Flags               01 (1) 'Modification'
│ │ │ │ +9F180   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F184 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F186   Length              000B (11)
│ │ │ │ +9F188   Version             01 (1)
│ │ │ │ +9F189   UID Size            04 (4)
│ │ │ │ +9F18A   UID                 00000000 (0)
│ │ │ │ +9F18E   GID Size            04 (4)
│ │ │ │ +9F18F   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F193 CENTRAL HEADER #61    02014B50 (33639248)
│ │ │ │ +9F197 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F198 Created OS            03 (3) 'Unix'
│ │ │ │ +9F199 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F19A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F19B General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F19D Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F19F Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F1A3 CRC                   5D7EB216 (1568584214)
│ │ │ │ +9F1A7 Compressed Size       00000EFA (3834)
│ │ │ │ +9F1AB Uncompressed Size     00003A2C (14892)
│ │ │ │ +9F1AF Filename Length       0024 (36)
│ │ │ │ +9F1B1 Extra Length          0018 (24)
│ │ │ │ +9F1B3 Comment Length        0000 (0)
│ │ │ │ +9F1B5 Disk Start            0000 (0)
│ │ │ │ +9F1B7 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F1B9 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F1BD Local Header Offset   0006D3C0 (447424)
│ │ │ │ +9F1C1 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F1C1: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F1E5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F1E7   Length              0005 (5)
│ │ │ │ +9F1E9   Flags               01 (1) 'Modification'
│ │ │ │ +9F1EA   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F1EE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F1F0   Length              000B (11)
│ │ │ │ +9F1F2   Version             01 (1)
│ │ │ │ +9F1F3   UID Size            04 (4)
│ │ │ │ +9F1F4   UID                 00000000 (0)
│ │ │ │ +9F1F8   GID Size            04 (4)
│ │ │ │ +9F1F9   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F1FD CENTRAL HEADER #62    02014B50 (33639248)
│ │ │ │ +9F201 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F202 Created OS            03 (3) 'Unix'
│ │ │ │ +9F203 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F204 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F205 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F207 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F209 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F20D CRC                   AC96636E (2895537006)
│ │ │ │ +9F211 Compressed Size       00001AC0 (6848)
│ │ │ │ +9F215 Uncompressed Size     00005EDC (24284)
│ │ │ │ +9F219 Filename Length       0017 (23)
│ │ │ │ +9F21B Extra Length          0018 (24)
│ │ │ │ +9F21D Comment Length        0000 (0)
│ │ │ │ +9F21F Disk Start            0000 (0)
│ │ │ │ +9F221 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F223 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F227 Local Header Offset   0006E318 (451352)
│ │ │ │ +9F22B Filename              'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F22B: Filename 'XXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F242 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F244   Length              0005 (5)
│ │ │ │ +9F246   Flags               01 (1) 'Modification'
│ │ │ │ +9F247   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F24B Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F24D   Length              000B (11)
│ │ │ │ +9F24F   Version             01 (1)
│ │ │ │ +9F250   UID Size            04 (4)
│ │ │ │ +9F251   UID                 00000000 (0)
│ │ │ │ +9F255   GID Size            04 (4)
│ │ │ │ +9F256   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F25A CENTRAL HEADER #63    02014B50 (33639248)
│ │ │ │ +9F25E Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F25F Created OS            03 (3) 'Unix'
│ │ │ │ +9F260 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F261 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F262 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F264 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F266 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F26A CRC                   11E32AF1 (300100337)
│ │ │ │ +9F26E Compressed Size       00000ED3 (3795)
│ │ │ │ +9F272 Uncompressed Size     000038E2 (14562)
│ │ │ │ +9F276 Filename Length       0023 (35)
│ │ │ │ +9F278 Extra Length          0018 (24)
│ │ │ │ +9F27A Comment Length        0000 (0)
│ │ │ │ +9F27C Disk Start            0000 (0)
│ │ │ │ +9F27E Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F280 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F284 Local Header Offset   0006FE29 (458281)
│ │ │ │ +9F288 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F288: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F2AB Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F2AD   Length              0005 (5)
│ │ │ │ +9F2AF   Flags               01 (1) 'Modification'
│ │ │ │ +9F2B0   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F2B4 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F2B6   Length              000B (11)
│ │ │ │ +9F2B8   Version             01 (1)
│ │ │ │ +9F2B9   UID Size            04 (4)
│ │ │ │ +9F2BA   UID                 00000000 (0)
│ │ │ │ +9F2BE   GID Size            04 (4)
│ │ │ │ +9F2BF   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F2C3 CENTRAL HEADER #64    02014B50 (33639248)
│ │ │ │ +9F2C7 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F2C8 Created OS            03 (3) 'Unix'
│ │ │ │ +9F2C9 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F2CA Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F2CB General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F2CD Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F2CF Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F2D3 CRC                   2DB7929F (767005343)
│ │ │ │ +9F2D7 Compressed Size       00000113 (275)
│ │ │ │ +9F2DB Uncompressed Size     000001F3 (499)
│ │ │ │ +9F2DF Filename Length       001B (27)
│ │ │ │ +9F2E1 Extra Length          0018 (24)
│ │ │ │ +9F2E3 Comment Length        0000 (0)
│ │ │ │ +9F2E5 Disk Start            0000 (0)
│ │ │ │ +9F2E7 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F2E9 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F2ED Local Header Offset   00070D59 (462169)
│ │ │ │ +9F2F1 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F2F1: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F30C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F30E   Length              0005 (5)
│ │ │ │ +9F310   Flags               01 (1) 'Modification'
│ │ │ │ +9F311   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F315 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F317   Length              000B (11)
│ │ │ │ +9F319   Version             01 (1)
│ │ │ │ +9F31A   UID Size            04 (4)
│ │ │ │ +9F31B   UID                 00000000 (0)
│ │ │ │ +9F31F   GID Size            04 (4)
│ │ │ │ +9F320   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F324 CENTRAL HEADER #65    02014B50 (33639248)
│ │ │ │ +9F328 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F329 Created OS            03 (3) 'Unix'
│ │ │ │ +9F32A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F32B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F32C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F32E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F330 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F334 CRC                   BF2C5594 (3207353748)
│ │ │ │ +9F338 Compressed Size       00001890 (6288)
│ │ │ │ +9F33C Uncompressed Size     00008FAC (36780)
│ │ │ │ +9F340 Filename Length       001D (29)
│ │ │ │ +9F342 Extra Length          0018 (24)
│ │ │ │ +9F344 Comment Length        0000 (0)
│ │ │ │ +9F346 Disk Start            0000 (0)
│ │ │ │ +9F348 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F34A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F34E Local Header Offset   00070EC1 (462529)
│ │ │ │ +9F352 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F352: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F36F Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F371   Length              0005 (5)
│ │ │ │ +9F373   Flags               01 (1) 'Modification'
│ │ │ │ +9F374   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F378 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F37A   Length              000B (11)
│ │ │ │ +9F37C   Version             01 (1)
│ │ │ │ +9F37D   UID Size            04 (4)
│ │ │ │ +9F37E   UID                 00000000 (0)
│ │ │ │ +9F382   GID Size            04 (4)
│ │ │ │ +9F383   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F387 CENTRAL HEADER #66    02014B50 (33639248)
│ │ │ │ +9F38B Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F38C Created OS            03 (3) 'Unix'
│ │ │ │ +9F38D Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F38E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F38F General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F391 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F393 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F397 CRC                   63FED801 (1677645825)
│ │ │ │ +9F39B Compressed Size       0000164D (5709)
│ │ │ │ +9F39F Uncompressed Size     00003A9B (15003)
│ │ │ │ +9F3A3 Filename Length       0015 (21)
│ │ │ │ +9F3A5 Extra Length          0018 (24)
│ │ │ │ +9F3A7 Comment Length        0000 (0)
│ │ │ │ +9F3A9 Disk Start            0000 (0)
│ │ │ │ +9F3AB Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F3AD Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F3B1 Local Header Offset   000727A8 (468904)
│ │ │ │ +9F3B5 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F3B5: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F3CA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F3CC   Length              0005 (5)
│ │ │ │ +9F3CE   Flags               01 (1) 'Modification'
│ │ │ │ +9F3CF   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F3D3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F3D5   Length              000B (11)
│ │ │ │ +9F3D7   Version             01 (1)
│ │ │ │ +9F3D8   UID Size            04 (4)
│ │ │ │ +9F3D9   UID                 00000000 (0)
│ │ │ │ +9F3DD   GID Size            04 (4)
│ │ │ │ +9F3DE   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F3E2 CENTRAL HEADER #67    02014B50 (33639248)
│ │ │ │ +9F3E6 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F3E7 Created OS            03 (3) 'Unix'
│ │ │ │ +9F3E8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F3E9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F3EA General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F3EC Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F3EE Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F3F2 CRC                   C4C757ED (3301398509)
│ │ │ │ +9F3F6 Compressed Size       00003B50 (15184)
│ │ │ │ +9F3FA Uncompressed Size     0001185B (71771)
│ │ │ │ +9F3FE Filename Length       0016 (22)
│ │ │ │ +9F400 Extra Length          0018 (24)
│ │ │ │ +9F402 Comment Length        0000 (0)
│ │ │ │ +9F404 Disk Start            0000 (0)
│ │ │ │ +9F406 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F408 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F40C Local Header Offset   00073E44 (474692)
│ │ │ │ +9F410 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F410: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F426 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F428   Length              0005 (5)
│ │ │ │ +9F42A   Flags               01 (1) 'Modification'
│ │ │ │ +9F42B   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F42F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F431   Length              000B (11)
│ │ │ │ +9F433   Version             01 (1)
│ │ │ │ +9F434   UID Size            04 (4)
│ │ │ │ +9F435   UID                 00000000 (0)
│ │ │ │ +9F439   GID Size            04 (4)
│ │ │ │ +9F43A   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F43E CENTRAL HEADER #68    02014B50 (33639248)
│ │ │ │ +9F442 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F443 Created OS            03 (3) 'Unix'
│ │ │ │ +9F444 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F445 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F446 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F448 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F44A Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F44E CRC                   4A54A065 (1247060069)
│ │ │ │ +9F452 Compressed Size       00003E86 (16006)
│ │ │ │ +9F456 Uncompressed Size     0001C17B (115067)
│ │ │ │ +9F45A Filename Length       0019 (25)
│ │ │ │ +9F45C Extra Length          0018 (24)
│ │ │ │ +9F45E Comment Length        0000 (0)
│ │ │ │ +9F460 Disk Start            0000 (0)
│ │ │ │ +9F462 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F464 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F468 Local Header Offset   000779E4 (489956)
│ │ │ │ +9F46C Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F46C: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F485 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F487   Length              0005 (5)
│ │ │ │ +9F489   Flags               01 (1) 'Modification'
│ │ │ │ +9F48A   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F48E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F490   Length              000B (11)
│ │ │ │ +9F492   Version             01 (1)
│ │ │ │ +9F493   UID Size            04 (4)
│ │ │ │ +9F494   UID                 00000000 (0)
│ │ │ │ +9F498   GID Size            04 (4)
│ │ │ │ +9F499   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F49D CENTRAL HEADER #69    02014B50 (33639248)
│ │ │ │ +9F4A1 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F4A2 Created OS            03 (3) 'Unix'
│ │ │ │ +9F4A3 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F4A4 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F4A5 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F4A7 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F4A9 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F4AD CRC                   04806937 (75524407)
│ │ │ │ +9F4B1 Compressed Size       00000838 (2104)
│ │ │ │ +9F4B5 Uncompressed Size     00003383 (13187)
│ │ │ │ +9F4B9 Filename Length       0011 (17)
│ │ │ │ +9F4BB Extra Length          0018 (24)
│ │ │ │ +9F4BD Comment Length        0000 (0)
│ │ │ │ +9F4BF Disk Start            0000 (0)
│ │ │ │ +9F4C1 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F4C3 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F4C7 Local Header Offset   0007B8BD (506045)
│ │ │ │ +9F4CB Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F4CB: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F4DC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F4DE   Length              0005 (5)
│ │ │ │ +9F4E0   Flags               01 (1) 'Modification'
│ │ │ │ +9F4E1   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F4E5 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F4E7   Length              000B (11)
│ │ │ │ +9F4E9   Version             01 (1)
│ │ │ │ +9F4EA   UID Size            04 (4)
│ │ │ │ +9F4EB   UID                 00000000 (0)
│ │ │ │ +9F4EF   GID Size            04 (4)
│ │ │ │ +9F4F0   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F4F4 CENTRAL HEADER #70    02014B50 (33639248)
│ │ │ │ +9F4F8 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F4F9 Created OS            03 (3) 'Unix'
│ │ │ │ +9F4FA Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F4FB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F4FC General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F4FE Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F500 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F504 CRC                   02DF6A89 (48196233)
│ │ │ │ +9F508 Compressed Size       00005188 (20872)
│ │ │ │ +9F50C Uncompressed Size     0001FB6C (129900)
│ │ │ │ +9F510 Filename Length       0015 (21)
│ │ │ │ +9F512 Extra Length          0018 (24)
│ │ │ │ +9F514 Comment Length        0000 (0)
│ │ │ │ +9F516 Disk Start            0000 (0)
│ │ │ │ +9F518 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F51A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F51E Local Header Offset   0007C140 (508224)
│ │ │ │ +9F522 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F522: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F537 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F539   Length              0005 (5)
│ │ │ │ +9F53B   Flags               01 (1) 'Modification'
│ │ │ │ +9F53C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F540 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F542   Length              000B (11)
│ │ │ │ +9F544   Version             01 (1)
│ │ │ │ +9F545   UID Size            04 (4)
│ │ │ │ +9F546   UID                 00000000 (0)
│ │ │ │ +9F54A   GID Size            04 (4)
│ │ │ │ +9F54B   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F54F CENTRAL HEADER #71    02014B50 (33639248)
│ │ │ │ +9F553 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F554 Created OS            03 (3) 'Unix'
│ │ │ │ +9F555 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F556 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F557 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F559 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F55B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F55F CRC                   9F6D82FD (2674754301)
│ │ │ │ +9F563 Compressed Size       00001B09 (6921)
│ │ │ │ +9F567 Uncompressed Size     000081CF (33231)
│ │ │ │ +9F56B Filename Length       0019 (25)
│ │ │ │ +9F56D Extra Length          0018 (24)
│ │ │ │ +9F56F Comment Length        0000 (0)
│ │ │ │ +9F571 Disk Start            0000 (0)
│ │ │ │ +9F573 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F575 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F579 Local Header Offset   00081317 (529175)
│ │ │ │ +9F57D Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F57D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F596 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F598   Length              0005 (5)
│ │ │ │ +9F59A   Flags               01 (1) 'Modification'
│ │ │ │ +9F59B   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F59F Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F5A1   Length              000B (11)
│ │ │ │ +9F5A3   Version             01 (1)
│ │ │ │ +9F5A4   UID Size            04 (4)
│ │ │ │ +9F5A5   UID                 00000000 (0)
│ │ │ │ +9F5A9   GID Size            04 (4)
│ │ │ │ +9F5AA   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F5AE CENTRAL HEADER #72    02014B50 (33639248)
│ │ │ │ +9F5B2 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F5B3 Created OS            03 (3) 'Unix'
│ │ │ │ +9F5B4 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F5B5 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F5B6 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F5B8 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F5BA Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F5BE CRC                   112D8470 (288195696)
│ │ │ │ +9F5C2 Compressed Size       00000D97 (3479)
│ │ │ │ +9F5C6 Uncompressed Size     00002E9F (11935)
│ │ │ │ +9F5CA Filename Length       0018 (24)
│ │ │ │ +9F5CC Extra Length          0018 (24)
│ │ │ │ +9F5CE Comment Length        0000 (0)
│ │ │ │ +9F5D0 Disk Start            0000 (0)
│ │ │ │ +9F5D2 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F5D4 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F5D8 Local Header Offset   00082E73 (536179)
│ │ │ │ +9F5DC Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F5DC: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F5F4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F5F6   Length              0005 (5)
│ │ │ │ +9F5F8   Flags               01 (1) 'Modification'
│ │ │ │ +9F5F9   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F5FD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F5FF   Length              000B (11)
│ │ │ │ +9F601   Version             01 (1)
│ │ │ │ +9F602   UID Size            04 (4)
│ │ │ │ +9F603   UID                 00000000 (0)
│ │ │ │ +9F607   GID Size            04 (4)
│ │ │ │ +9F608   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F60C CENTRAL HEADER #73    02014B50 (33639248)
│ │ │ │ +9F610 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F611 Created OS            03 (3) 'Unix'
│ │ │ │ +9F612 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F613 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F614 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F616 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F618 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F61C CRC                   B429472D (3022604077)
│ │ │ │ +9F620 Compressed Size       000001E1 (481)
│ │ │ │ +9F624 Uncompressed Size     00000323 (803)
│ │ │ │ +9F628 Filename Length       0011 (17)
│ │ │ │ +9F62A Extra Length          0018 (24)
│ │ │ │ +9F62C Comment Length        0000 (0)
│ │ │ │ +9F62E Disk Start            0000 (0)
│ │ │ │ +9F630 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F632 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F636 Local Header Offset   00083C5C (539740)
│ │ │ │ +9F63A Filename              'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F63A: Filename 'XXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F64B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F64D   Length              0005 (5)
│ │ │ │ +9F64F   Flags               01 (1) 'Modification'
│ │ │ │ +9F650   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F654 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F656   Length              000B (11)
│ │ │ │ +9F658   Version             01 (1)
│ │ │ │ +9F659   UID Size            04 (4)
│ │ │ │ +9F65A   UID                 00000000 (0)
│ │ │ │ +9F65E   GID Size            04 (4)
│ │ │ │ +9F65F   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F663 CENTRAL HEADER #74    02014B50 (33639248)
│ │ │ │ +9F667 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F668 Created OS            03 (3) 'Unix'
│ │ │ │ +9F669 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F66A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F66B General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F66D Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F66F Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F673 CRC                   1E45F0E3 (507900131)
│ │ │ │ +9F677 Compressed Size       000006C1 (1729)
│ │ │ │ +9F67B Uncompressed Size     00001439 (5177)
│ │ │ │ +9F67F Filename Length       0019 (25)
│ │ │ │ +9F681 Extra Length          0018 (24)
│ │ │ │ +9F683 Comment Length        0000 (0)
│ │ │ │ +9F685 Disk Start            0000 (0)
│ │ │ │ +9F687 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F689 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F68D Local Header Offset   00083E88 (540296)
│ │ │ │ +9F691 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F691: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F6AA Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F6AC   Length              0005 (5)
│ │ │ │ +9F6AE   Flags               01 (1) 'Modification'
│ │ │ │ +9F6AF   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F6B3 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F6B5   Length              000B (11)
│ │ │ │ +9F6B7   Version             01 (1)
│ │ │ │ +9F6B8   UID Size            04 (4)
│ │ │ │ +9F6B9   UID                 00000000 (0)
│ │ │ │ +9F6BD   GID Size            04 (4)
│ │ │ │ +9F6BE   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F6C2 CENTRAL HEADER #75    02014B50 (33639248)
│ │ │ │ +9F6C6 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F6C7 Created OS            03 (3) 'Unix'
│ │ │ │ +9F6C8 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F6C9 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F6CA General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F6CC Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F6CE Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F6D2 CRC                   2E699024 (778670116)
│ │ │ │ +9F6D6 Compressed Size       00001B8B (7051)
│ │ │ │ +9F6DA Uncompressed Size     00009F03 (40707)
│ │ │ │ +9F6DE Filename Length       0018 (24)
│ │ │ │ +9F6E0 Extra Length          0018 (24)
│ │ │ │ +9F6E2 Comment Length        0000 (0)
│ │ │ │ +9F6E4 Disk Start            0000 (0)
│ │ │ │ +9F6E6 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F6E8 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F6EC Local Header Offset   0008459C (542108)
│ │ │ │ +9F6F0 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F6F0: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F708 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F70A   Length              0005 (5)
│ │ │ │ +9F70C   Flags               01 (1) 'Modification'
│ │ │ │ +9F70D   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F711 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F713   Length              000B (11)
│ │ │ │ +9F715   Version             01 (1)
│ │ │ │ +9F716   UID Size            04 (4)
│ │ │ │ +9F717   UID                 00000000 (0)
│ │ │ │ +9F71B   GID Size            04 (4)
│ │ │ │ +9F71C   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F720 CENTRAL HEADER #76    02014B50 (33639248)
│ │ │ │ +9F724 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F725 Created OS            03 (3) 'Unix'
│ │ │ │ +9F726 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F727 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F728 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F72A Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F72C Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F730 CRC                   59BB50F3 (1505448179)
│ │ │ │ +9F734 Compressed Size       000016F9 (5881)
│ │ │ │ +9F738 Uncompressed Size     00008AB6 (35510)
│ │ │ │ +9F73C Filename Length       0012 (18)
│ │ │ │ +9F73E Extra Length          0018 (24)
│ │ │ │ +9F740 Comment Length        0000 (0)
│ │ │ │ +9F742 Disk Start            0000 (0)
│ │ │ │ +9F744 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F746 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F74A Local Header Offset   00086179 (549241)
│ │ │ │ +9F74E Filename              'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F74E: Filename 'XXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F760 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F762   Length              0005 (5)
│ │ │ │ +9F764   Flags               01 (1) 'Modification'
│ │ │ │ +9F765   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F769 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F76B   Length              000B (11)
│ │ │ │ +9F76D   Version             01 (1)
│ │ │ │ +9F76E   UID Size            04 (4)
│ │ │ │ +9F76F   UID                 00000000 (0)
│ │ │ │ +9F773   GID Size            04 (4)
│ │ │ │ +9F774   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F778 CENTRAL HEADER #77    02014B50 (33639248)
│ │ │ │ +9F77C Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F77D Created OS            03 (3) 'Unix'
│ │ │ │ +9F77E Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F77F Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F780 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F782 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F784 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F788 CRC                   EA21F703 (3928094467)
│ │ │ │ +9F78C Compressed Size       00001E13 (7699)
│ │ │ │ +9F790 Uncompressed Size     00008803 (34819)
│ │ │ │ +9F794 Filename Length       0016 (22)
│ │ │ │ +9F796 Extra Length          0018 (24)
│ │ │ │ +9F798 Comment Length        0000 (0)
│ │ │ │ +9F79A Disk Start            0000 (0)
│ │ │ │ +9F79C Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F79E Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F7A2 Local Header Offset   000878BE (555198)
│ │ │ │ +9F7A6 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F7A6: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F7BC Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F7BE   Length              0005 (5)
│ │ │ │ +9F7C0   Flags               01 (1) 'Modification'
│ │ │ │ +9F7C1   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F7C5 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F7C7   Length              000B (11)
│ │ │ │ +9F7C9   Version             01 (1)
│ │ │ │ +9F7CA   UID Size            04 (4)
│ │ │ │ +9F7CB   UID                 00000000 (0)
│ │ │ │ +9F7CF   GID Size            04 (4)
│ │ │ │ +9F7D0   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F7D4 CENTRAL HEADER #78    02014B50 (33639248)
│ │ │ │ +9F7D8 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F7D9 Created OS            03 (3) 'Unix'
│ │ │ │ +9F7DA Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F7DB Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F7DC General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F7DE Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F7E0 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F7E4 CRC                   F5D80FF6 (4124577782)
│ │ │ │ +9F7E8 Compressed Size       000029A8 (10664)
│ │ │ │ +9F7EC Uncompressed Size     0000D04F (53327)
│ │ │ │ +9F7F0 Filename Length       001A (26)
│ │ │ │ +9F7F2 Extra Length          0018 (24)
│ │ │ │ +9F7F4 Comment Length        0000 (0)
│ │ │ │ +9F7F6 Disk Start            0000 (0)
│ │ │ │ +9F7F8 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F7FA Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F7FE Local Header Offset   00089721 (562977)
│ │ │ │ +9F802 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F802: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F81C Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F81E   Length              0005 (5)
│ │ │ │ +9F820   Flags               01 (1) 'Modification'
│ │ │ │ +9F821   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F825 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F827   Length              000B (11)
│ │ │ │ +9F829   Version             01 (1)
│ │ │ │ +9F82A   UID Size            04 (4)
│ │ │ │ +9F82B   UID                 00000000 (0)
│ │ │ │ +9F82F   GID Size            04 (4)
│ │ │ │ +9F830   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F834 CENTRAL HEADER #79    02014B50 (33639248)
│ │ │ │ +9F838 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F839 Created OS            03 (3) 'Unix'
│ │ │ │ +9F83A Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F83B Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F83C General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F83E Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F840 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F844 CRC                   B50D8ED4 (3037564628)
│ │ │ │ +9F848 Compressed Size       000009AC (2476)
│ │ │ │ +9F84C Uncompressed Size     00001DB6 (7606)
│ │ │ │ +9F850 Filename Length       0018 (24)
│ │ │ │ +9F852 Extra Length          0018 (24)
│ │ │ │ +9F854 Comment Length        0000 (0)
│ │ │ │ +9F856 Disk Start            0000 (0)
│ │ │ │ +9F858 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F85A Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F85E Local Header Offset   0008C11D (573725)
│ │ │ │ +9F862 Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F862: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F87A Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F87C   Length              0005 (5)
│ │ │ │ +9F87E   Flags               01 (1) 'Modification'
│ │ │ │ +9F87F   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F883 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F885   Length              000B (11)
│ │ │ │ +9F887   Version             01 (1)
│ │ │ │ +9F888   UID Size            04 (4)
│ │ │ │ +9F889   UID                 00000000 (0)
│ │ │ │ +9F88D   GID Size            04 (4)
│ │ │ │ +9F88E   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F892 CENTRAL HEADER #80    02014B50 (33639248)
│ │ │ │ +9F896 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F897 Created OS            03 (3) 'Unix'
│ │ │ │ +9F898 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F899 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F89A General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F89C Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F89E Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F8A2 CRC                   F5E2129F (4125233823)
│ │ │ │ +9F8A6 Compressed Size       000016BC (5820)
│ │ │ │ +9F8AA Uncompressed Size     000016CD (5837)
│ │ │ │ +9F8AE Filename Length       0015 (21)
│ │ │ │ +9F8B0 Extra Length          0018 (24)
│ │ │ │ +9F8B2 Comment Length        0000 (0)
│ │ │ │ +9F8B4 Disk Start            0000 (0)
│ │ │ │ +9F8B6 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F8B8 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F8BC Local Header Offset   0008CB1B (576283)
│ │ │ │ +9F8C0 Filename              'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F8C0: Filename 'XXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F8D5 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F8D7   Length              0005 (5)
│ │ │ │ +9F8D9   Flags               01 (1) 'Modification'
│ │ │ │ +9F8DA   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F8DE Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F8E0   Length              000B (11)
│ │ │ │ +9F8E2   Version             01 (1)
│ │ │ │ +9F8E3   UID Size            04 (4)
│ │ │ │ +9F8E4   UID                 00000000 (0)
│ │ │ │ +9F8E8   GID Size            04 (4)
│ │ │ │ +9F8E9   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F8ED CENTRAL HEADER #81    02014B50 (33639248)
│ │ │ │ +9F8F1 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F8F2 Created OS            03 (3) 'Unix'
│ │ │ │ +9F8F3 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9F8F4 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F8F5 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9F8F7 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9F8F9 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F8FD CRC                   F5E2129F (4125233823)
│ │ │ │ +9F901 Compressed Size       000016BC (5820)
│ │ │ │ +9F905 Uncompressed Size     000016CD (5837)
│ │ │ │ +9F909 Filename Length       001C (28)
│ │ │ │ +9F90B Extra Length          0018 (24)
│ │ │ │ +9F90D Comment Length        0000 (0)
│ │ │ │ +9F90F Disk Start            0000 (0)
│ │ │ │ +9F911 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F913 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F917 Local Header Offset   0008E226 (582182)
│ │ │ │ +9F91B Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F91B: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F937 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F939   Length              0005 (5)
│ │ │ │ +9F93B   Flags               01 (1) 'Modification'
│ │ │ │ +9F93C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F940 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F942   Length              000B (11)
│ │ │ │ +9F944   Version             01 (1)
│ │ │ │ +9F945   UID Size            04 (4)
│ │ │ │ +9F946   UID                 00000000 (0)
│ │ │ │ +9F94A   GID Size            04 (4)
│ │ │ │ +9F94B   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F94F CENTRAL HEADER #82    02014B50 (33639248)
│ │ │ │ +9F953 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F954 Created OS            03 (3) 'Unix'
│ │ │ │ +9F955 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +9F956 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F957 General Purpose Flag  0000 (0)
│ │ │ │ +9F959 Compression Method    0000 (0) 'Stored'
│ │ │ │ +9F95B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F95F CRC                   FC95F24B (4237685323)
│ │ │ │ +9F963 Compressed Size       00001B84 (7044)
│ │ │ │ +9F967 Uncompressed Size     00001B84 (7044)
│ │ │ │ +9F96B Filename Length       0016 (22)
│ │ │ │ +9F96D Extra Length          0018 (24)
│ │ │ │ +9F96F Comment Length        0000 (0)
│ │ │ │ +9F971 Disk Start            0000 (0)
│ │ │ │ +9F973 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F975 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F979 Local Header Offset   0008F938 (588088)
│ │ │ │ +9F97D Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F97D: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F993 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F995   Length              0005 (5)
│ │ │ │ +9F997   Flags               01 (1) 'Modification'
│ │ │ │ +9F998   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F99C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F99E   Length              000B (11)
│ │ │ │ +9F9A0   Version             01 (1)
│ │ │ │ +9F9A1   UID Size            04 (4)
│ │ │ │ +9F9A2   UID                 00000000 (0)
│ │ │ │ +9F9A6   GID Size            04 (4)
│ │ │ │ +9F9A7   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9F9AB CENTRAL HEADER #83    02014B50 (33639248)
│ │ │ │ +9F9AF Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9F9B0 Created OS            03 (3) 'Unix'
│ │ │ │ +9F9B1 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +9F9B2 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9F9B3 General Purpose Flag  0000 (0)
│ │ │ │ +9F9B5 Compression Method    0000 (0) 'Stored'
│ │ │ │ +9F9B7 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F9BB CRC                   D0D71F86 (3503759238)
│ │ │ │ +9F9BF Compressed Size       00000B7B (2939)
│ │ │ │ +9F9C3 Uncompressed Size     00000B7B (2939)
│ │ │ │ +9F9C7 Filename Length       0016 (22)
│ │ │ │ +9F9C9 Extra Length          0018 (24)
│ │ │ │ +9F9CB Comment Length        0000 (0)
│ │ │ │ +9F9CD Disk Start            0000 (0)
│ │ │ │ +9F9CF Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9F9D1 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9F9D5 Local Header Offset   0009150C (595212)
│ │ │ │ +9F9D9 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9F9D9: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9F9EF Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9F9F1   Length              0005 (5)
│ │ │ │ +9F9F3   Flags               01 (1) 'Modification'
│ │ │ │ +9F9F4   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9F9F8 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9F9FA   Length              000B (11)
│ │ │ │ +9F9FC   Version             01 (1)
│ │ │ │ +9F9FD   UID Size            04 (4)
│ │ │ │ +9F9FE   UID                 00000000 (0)
│ │ │ │ +9FA02   GID Size            04 (4)
│ │ │ │ +9FA03   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FA07 CENTRAL HEADER #84    02014B50 (33639248)
│ │ │ │ +9FA0B Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FA0C Created OS            03 (3) 'Unix'
│ │ │ │ +9FA0D Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +9FA0E Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FA0F General Purpose Flag  0000 (0)
│ │ │ │ +9FA11 Compression Method    0000 (0) 'Stored'
│ │ │ │ +9FA13 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FA17 CRC                   FFF9C4D2 (4294558930)
│ │ │ │ +9FA1B Compressed Size       0000138F (5007)
│ │ │ │ +9FA1F Uncompressed Size     0000138F (5007)
│ │ │ │ +9FA23 Filename Length       0016 (22)
│ │ │ │ +9FA25 Extra Length          0018 (24)
│ │ │ │ +9FA27 Comment Length        0000 (0)
│ │ │ │ +9FA29 Disk Start            0000 (0)
│ │ │ │ +9FA2B Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FA2D Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FA31 Local Header Offset   000920D7 (598231)
│ │ │ │ +9FA35 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FA35: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FA4B Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FA4D   Length              0005 (5)
│ │ │ │ +9FA4F   Flags               01 (1) 'Modification'
│ │ │ │ +9FA50   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FA54 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FA56   Length              000B (11)
│ │ │ │ +9FA58   Version             01 (1)
│ │ │ │ +9FA59   UID Size            04 (4)
│ │ │ │ +9FA5A   UID                 00000000 (0)
│ │ │ │ +9FA5E   GID Size            04 (4)
│ │ │ │ +9FA5F   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FA63 CENTRAL HEADER #85    02014B50 (33639248)
│ │ │ │ +9FA67 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FA68 Created OS            03 (3) 'Unix'
│ │ │ │ +9FA69 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +9FA6A Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FA6B General Purpose Flag  0000 (0)
│ │ │ │ +9FA6D Compression Method    0000 (0) 'Stored'
│ │ │ │ +9FA6F Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FA73 CRC                   A1037E8E (2701360782)
│ │ │ │ +9FA77 Compressed Size       0000145E (5214)
│ │ │ │ +9FA7B Uncompressed Size     0000145E (5214)
│ │ │ │ +9FA7F Filename Length       0016 (22)
│ │ │ │ +9FA81 Extra Length          0018 (24)
│ │ │ │ +9FA83 Comment Length        0000 (0)
│ │ │ │ +9FA85 Disk Start            0000 (0)
│ │ │ │ +9FA87 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FA89 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FA8D Local Header Offset   000934B6 (603318)
│ │ │ │ +9FA91 Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FA91: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FAA7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FAA9   Length              0005 (5)
│ │ │ │ +9FAAB   Flags               01 (1) 'Modification'
│ │ │ │ +9FAAC   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FAB0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FAB2   Length              000B (11)
│ │ │ │ +9FAB4   Version             01 (1)
│ │ │ │ +9FAB5   UID Size            04 (4)
│ │ │ │ +9FAB6   UID                 00000000 (0)
│ │ │ │ +9FABA   GID Size            04 (4)
│ │ │ │ +9FABB   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FABF CENTRAL HEADER #86    02014B50 (33639248)
│ │ │ │ +9FAC3 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FAC4 Created OS            03 (3) 'Unix'
│ │ │ │ +9FAC5 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +9FAC6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FAC7 General Purpose Flag  0000 (0)
│ │ │ │ +9FAC9 Compression Method    0000 (0) 'Stored'
│ │ │ │ +9FACB Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FACF CRC                   5E9E64F1 (1587438833)
│ │ │ │ +9FAD3 Compressed Size       000008EC (2284)
│ │ │ │ +9FAD7 Uncompressed Size     000008EC (2284)
│ │ │ │ +9FADB Filename Length       0016 (22)
│ │ │ │ +9FADD Extra Length          0018 (24)
│ │ │ │ +9FADF Comment Length        0000 (0)
│ │ │ │ +9FAE1 Disk Start            0000 (0)
│ │ │ │ +9FAE3 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FAE5 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FAE9 Local Header Offset   00094964 (608612)
│ │ │ │ +9FAED Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FAED: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FB03 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FB05   Length              0005 (5)
│ │ │ │ +9FB07   Flags               01 (1) 'Modification'
│ │ │ │ +9FB08   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FB0C Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FB0E   Length              000B (11)
│ │ │ │ +9FB10   Version             01 (1)
│ │ │ │ +9FB11   UID Size            04 (4)
│ │ │ │ +9FB12   UID                 00000000 (0)
│ │ │ │ +9FB16   GID Size            04 (4)
│ │ │ │ +9FB17   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FB1B CENTRAL HEADER #87    02014B50 (33639248)
│ │ │ │ +9FB1F Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FB20 Created OS            03 (3) 'Unix'
│ │ │ │ +9FB21 Extract Zip Spec      0A (10) '1.0'
│ │ │ │ +9FB22 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FB23 General Purpose Flag  0000 (0)
│ │ │ │ +9FB25 Compression Method    0000 (0) 'Stored'
│ │ │ │ +9FB27 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FB2B CRC                   42E340AB (1122189483)
│ │ │ │ +9FB2F Compressed Size       00001F2E (7982)
│ │ │ │ +9FB33 Uncompressed Size     00001F2E (7982)
│ │ │ │ +9FB37 Filename Length       001E (30)
│ │ │ │ +9FB39 Extra Length          0018 (24)
│ │ │ │ +9FB3B Comment Length        0000 (0)
│ │ │ │ +9FB3D Disk Start            0000 (0)
│ │ │ │ +9FB3F Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FB41 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FB45 Local Header Offset   000952A0 (610976)
│ │ │ │ +9FB49 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FB49: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FB67 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FB69   Length              0005 (5)
│ │ │ │ +9FB6B   Flags               01 (1) 'Modification'
│ │ │ │ +9FB6C   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FB70 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FB72   Length              000B (11)
│ │ │ │ +9FB74   Version             01 (1)
│ │ │ │ +9FB75   UID Size            04 (4)
│ │ │ │ +9FB76   UID                 00000000 (0)
│ │ │ │ +9FB7A   GID Size            04 (4)
│ │ │ │ +9FB7B   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FB7F CENTRAL HEADER #88    02014B50 (33639248)
│ │ │ │ +9FB83 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FB84 Created OS            03 (3) 'Unix'
│ │ │ │ +9FB85 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9FB86 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FB87 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9FB89 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9FB8B Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FB8F CRC                   A35733FC (2740401148)
│ │ │ │ +9FB93 Compressed Size       00003D72 (15730)
│ │ │ │ +9FB97 Uncompressed Size     00016649 (91721)
│ │ │ │ +9FB9B Filename Length       001A (26)
│ │ │ │ +9FB9D Extra Length          0018 (24)
│ │ │ │ +9FB9F Comment Length        0000 (0)
│ │ │ │ +9FBA1 Disk Start            0000 (0)
│ │ │ │ +9FBA3 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FBA5 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FBA9 Local Header Offset   00097226 (619046)
│ │ │ │ +9FBAD Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FBAD: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FBC7 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FBC9   Length              0005 (5)
│ │ │ │ +9FBCB   Flags               01 (1) 'Modification'
│ │ │ │ +9FBCC   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FBD0 Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FBD2   Length              000B (11)
│ │ │ │ +9FBD4   Version             01 (1)
│ │ │ │ +9FBD5   UID Size            04 (4)
│ │ │ │ +9FBD6   UID                 00000000 (0)
│ │ │ │ +9FBDA   GID Size            04 (4)
│ │ │ │ +9FBDB   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FBDF CENTRAL HEADER #89    02014B50 (33639248)
│ │ │ │ +9FBE3 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FBE4 Created OS            03 (3) 'Unix'
│ │ │ │ +9FBE5 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9FBE6 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FBE7 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9FBE9 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9FBEB Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FBEF CRC                   FC5489FE (4233398782)
│ │ │ │ +9FBF3 Compressed Size       000029BD (10685)
│ │ │ │ +9FBF7 Uncompressed Size     0000BA6A (47722)
│ │ │ │ +9FBFB Filename Length       0018 (24)
│ │ │ │ +9FBFD Extra Length          0018 (24)
│ │ │ │ +9FBFF Comment Length        0000 (0)
│ │ │ │ +9FC01 Disk Start            0000 (0)
│ │ │ │ +9FC03 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FC05 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FC09 Local Header Offset   0009AFEC (634860)
│ │ │ │ +9FC0D Filename              'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FC0D: Filename 'XXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FC25 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FC27   Length              0005 (5)
│ │ │ │ +9FC29   Flags               01 (1) 'Modification'
│ │ │ │ +9FC2A   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FC2E Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FC30   Length              000B (11)
│ │ │ │ +9FC32   Version             01 (1)
│ │ │ │ +9FC33   UID Size            04 (4)
│ │ │ │ +9FC34   UID                 00000000 (0)
│ │ │ │ +9FC38   GID Size            04 (4)
│ │ │ │ +9FC39   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FC3D CENTRAL HEADER #90    02014B50 (33639248)
│ │ │ │ +9FC41 Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FC42 Created OS            03 (3) 'Unix'
│ │ │ │ +9FC43 Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9FC44 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FC45 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9FC47 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9FC49 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FC4D CRC                   DCB3B516 (3702764822)
│ │ │ │ +9FC51 Compressed Size       000000AE (174)
│ │ │ │ +9FC55 Uncompressed Size     000000FC (252)
│ │ │ │ +9FC59 Filename Length       0016 (22)
│ │ │ │ +9FC5B Extra Length          0018 (24)
│ │ │ │ +9FC5D Comment Length        0000 (0)
│ │ │ │ +9FC5F Disk Start            0000 (0)
│ │ │ │ +9FC61 Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FC63 Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FC67 Local Header Offset   0009D9FB (645627)
│ │ │ │ +9FC6B Filename              'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FC6B: Filename 'XXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FC81 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FC83   Length              0005 (5)
│ │ │ │ +9FC85   Flags               01 (1) 'Modification'
│ │ │ │ +9FC86   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FC8A Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FC8C   Length              000B (11)
│ │ │ │ +9FC8E   Version             01 (1)
│ │ │ │ +9FC8F   UID Size            04 (4)
│ │ │ │ +9FC90   UID                 00000000 (0)
│ │ │ │ +9FC94   GID Size            04 (4)
│ │ │ │ +9FC95   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FC99 CENTRAL HEADER #91    02014B50 (33639248)
│ │ │ │ +9FC9D Created Zip Spec      3D (61) '6.1'
│ │ │ │ +9FC9E Created OS            03 (3) 'Unix'
│ │ │ │ +9FC9F Extract Zip Spec      14 (20) '2.0'
│ │ │ │ +9FCA0 Extract OS            00 (0) 'MS-DOS'
│ │ │ │ +9FCA1 General Purpose Flag  0000 (0)
│ │ │ │ +      [Bits 1-2]            0 'Normal Compression'
│ │ │ │ +9FCA3 Compression Method    0008 (8) 'Deflated'
│ │ │ │ +9FCA5 Modification Time     5B5F7B07 (1532984071) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FCA9 CRC                   58439733 (1480824627)
│ │ │ │ +9FCAD Compressed Size       00000077 (119)
│ │ │ │ +9FCB1 Uncompressed Size     000000A2 (162)
│ │ │ │ +9FCB5 Filename Length       002D (45)
│ │ │ │ +9FCB7 Extra Length          0018 (24)
│ │ │ │ +9FCB9 Comment Length        0000 (0)
│ │ │ │ +9FCBB Disk Start            0000 (0)
│ │ │ │ +9FCBD Int File Attributes   0000 (0)
│ │ │ │ +      [Bit 0]               0 'Binary Data'
│ │ │ │ +9FCBF Ext File Attributes   01A40000 (27525120)
│ │ │ │ +      [Bits 16-24]          01A4 (420) 'Unix attrib: rw-r--r--'
│ │ │ │ +9FCC3 Local Header Offset   0009DAF9 (645881)
│ │ │ │ +9FCC7 Filename              'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#
│ │ │ │ +# WARNING: Offset 0x9FCC7: Filename 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
│ │ │ │ +#          Zero length filename
│ │ │ │ +#
│ │ │ │ +9FCF4 Extra ID #1           5455 (21589) 'Extended Timestamp [UT]'
│ │ │ │ +9FCF6   Length              0005 (5)
│ │ │ │ +9FCF8   Flags               01 (1) 'Modification'
│ │ │ │ +9FCF9   Modification Time   6904D49E (1761924254) 'Fri Oct 31 15:24:14 2025'
│ │ │ │ +9FCFD Extra ID #2           7875 (30837) 'Unix Extra type 3 [ux]'
│ │ │ │ +9FCFF   Length              000B (11)
│ │ │ │ +9FD01   Version             01 (1)
│ │ │ │ +9FD02   UID Size            04 (4)
│ │ │ │ +9FD03   UID                 00000000 (0)
│ │ │ │ +9FD07   GID Size            04 (4)
│ │ │ │ +9FD08   GID                 00000000 (0)
│ │ │ │ +
│ │ │ │ +9FD0C END CENTRAL HEADER    06054B50 (101010256)
│ │ │ │ +9FD10 Number of this disk   0000 (0)
│ │ │ │ +9FD12 Central Dir Disk no   0000 (0)
│ │ │ │ +9FD14 Entries in this disk  005B (91)
│ │ │ │ +9FD16 Total Entries         005B (91)
│ │ │ │ +9FD18 Size of Central Dir   00002135 (8501)
│ │ │ │ +9FD1C Offset to Central Dir 0009DBD7 (646103)
│ │ │ │ +9FD20 Comment Length        0000 (0)
│ │ │ │  #
│ │ │ │  # Warning Count: 182
│ │ │ │  #
│ │ │ │  # Done
│ │ │ ├── filetype from file(1)
│ │ │ │ @@ -1 +1 @@
│ │ │ │ -Zip archive data, made by v6.1 UNIX, extract using at least v1.0, last modified Oct 31 2025 13:18:12, uncompressed size 20, method=store
│ │ │ │ +Zip archive data, made by v6.1 UNIX, extract using at least v1.0, last modified Oct 31 2025 15:24:14, uncompressed size 20, method=store
│ │ │ ├── OEBPS/typespec.xhtml
│ │ │ │ @@ -143,122 +143,122 @@
│ │ │ │  and optional <code class="inline">(=&gt;)</code> association types. If an association type is mandatory, an
│ │ │ │  association with that type needs to be present. In the case of an optional
│ │ │ │  association type it is not required for the key type to be present.</p><p>The notation <code class="inline">#{}</code> specifies the singleton type for the empty map. Note that
│ │ │ │  this notation is not a shorthand for the <a href="../../../lib/../erts/doc/html/erlang.html#t:map/0"><code class="inline">map/0</code></a> type.</p><p>For convenience, the following types are also built-in. They can be thought as
│ │ │ │  predefined aliases for the type unions also shown in the table.</p><p><a href="" id="builtin_types"></a></p><table><thead><tr><th style="text-align: left;"><em>Built-in type</em></th><th style="text-align: left;"><em>Defined as</em></th></tr></thead><tbody><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:term/0"><code class="inline">term/0</code></a></td><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:any/0"><code class="inline">any/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:binary/0"><code class="inline">binary/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:_*8&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:nonempty_binary/0"><code class="inline">nonempty_binary/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:8, _:_*8&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:bitstring/0"><code class="inline">bitstring/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:_*1&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:nonempty_bitstring/0"><code class="inline">nonempty_bitstring/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:1, _:_*1&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:boolean/0"><code class="inline">boolean/0</code></a></td><td style="text-align: left;"><code class="inline">'false'</code> | <code class="inline">'true'</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:byte/0"><code class="inline">byte/0</code></a></td><td style="text-align: left;"><code class="inline">0..255</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:char/0"><code class="inline">char/0</code></a></td><td style="text-align: left;"><code class="inline">0..16#10ffff</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:nil/0"><code class="inline">nil/0</code></a></td><td style="text-align: left;"><code class="inline">[]</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:number/0"><code class="inline">number/0</code></a></td><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:integer/0"><code class="inline">integer/0</code></a> | <a href="../../../lib/../erts/doc/html/erlang.html#t:float/0"><code class="inline">float/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:list/0"><code class="inline">list/0</code></a></td><td style="text-align: left;"><code class="inline">[any()]</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:maybe_improper_list/0"><code class="inline">maybe_improper_list/0</code></a></td><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:maybe_improper_list/2"><code class="inline">maybe_improper_list(any(), any())</code></a></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:nonempty_list/0"><code class="inline">nonempty_list/0</code></a></td><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:nonempty_list/1"><code class="inline">nonempty_list(any())</code></a></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:string/0"><code class="inline">string/0</code></a></td><td style="text-align: left;"><code class="inline">[char()]</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:nonempty_string/0"><code class="inline">nonempty_string/0</code></a></td><td style="text-align: left;"><code class="inline">[char(),...]</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:iodata/0"><code class="inline">iodata/0</code></a></td><td style="text-align: left;"><code class="inline">iolist()</code> | <code class="inline">binary()</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:iolist/0"><code class="inline">iolist/0</code></a></td><td style="text-align: left;"><code class="inline">maybe_improper_list(byte()</code> | <code class="inline">binary()</code> | <code class="inline">iolist(), binary()</code> | <code class="inline">[])</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:map/0"><code class="inline">map/0</code></a></td><td style="text-align: left;"><code class="inline">#{any() =&gt; any()}</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:function/0"><code class="inline">function/0</code></a></td><td style="text-align: left;"><code class="inline">fun()</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:module/0"><code class="inline">module/0</code></a></td><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:atom/0"><code class="inline">atom/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:mfa/0"><code class="inline">mfa/0</code></a></td><td style="text-align: left;"><code class="inline">{module(),atom(),arity()}</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:arity/0"><code class="inline">arity/0</code></a></td><td style="text-align: left;"><code class="inline">0..255</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:identifier/0"><code class="inline">identifier/0</code></a></td><td style="text-align: left;"><code class="inline">pid()</code> | <code class="inline">port()</code> | <code class="inline">reference()</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#node/0"><code class="inline">node/0</code></a></td><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:atom/0"><code class="inline">atom/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:timeout/0"><code class="inline">timeout/0</code></a></td><td style="text-align: left;"><code class="inline">'infinity'</code> | <code class="inline">non_neg_integer()</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:no_return/0"><code class="inline">no_return/0</code></a></td><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:none/0"><code class="inline">none/0</code></a></td></tr></tbody></table><p><em>Table: Built-in types, predefined aliases</em></p><p>In addition, the following three built-in types exist and can be thought as
│ │ │ │  defined below, though strictly their &quot;type definition&quot; is not valid syntax
│ │ │ │  according to the type language defined above.</p><table><thead><tr><th style="text-align: left;"><em>Built-in type</em></th><th style="text-align: left;"><em>Can be thought defined by the syntax</em></th></tr></thead><tbody><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:non_neg_integer/0"><code class="inline">non_neg_integer/0</code></a></td><td style="text-align: left;"><code class="inline">0..</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:pos_integer/0"><code class="inline">pos_integer/0</code></a></td><td style="text-align: left;"><code class="inline">1..</code></td></tr><tr><td style="text-align: left;"><a href="../../../lib/../erts/doc/html/erlang.html#t:neg_integer/0"><code class="inline">neg_integer/0</code></a></td><td style="text-align: left;"><code class="inline">..-1</code></td></tr></tbody></table><p><em>Table: Additional built-in types</em></p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The following built-in list types also exist, but they are expected to be
│ │ │ │ -rarely used. Hence, they have long names:</p></section><pre><code class="makeup erlang" translate="no"><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="4816480260-1">(</span><span class="p" data-group-id="4816480260-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="4816480260-2">(</span><span class="nf">any</span><span class="p" data-group-id="4816480260-3">(</span><span class="p" data-group-id="4816480260-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="4816480260-4">(</span><span class="p" data-group-id="4816480260-4">)</span><span class="p" data-group-id="4816480260-2">)</span><span class="w">
│ │ │ │ -</span><span class="nf">nonempty_improper_list</span><span class="p" data-group-id="4816480260-5">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="4816480260-5">)</span><span class="w">
│ │ │ │ -</span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="4816480260-6">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="4816480260-6">)</span></code></pre><p>where the last two types define the set of Erlang terms one would expect.</p><p>Also for convenience, record notation is allowed to be used. Records are
│ │ │ │ -shorthands for the corresponding tuples:</p><pre><code class="makeup erlang" translate="no"><span class="n">Record</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="0867450838-1">{</span><span class="p" data-group-id="0867450838-1">}</span><span class="w">
│ │ │ │ -        </span><span class="p">|</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="0867450838-2">{</span><span class="n">Fields</span><span class="p" data-group-id="0867450838-2">}</span></code></pre><p>Records are extended to possibly contain type information. This is described in
│ │ │ │ +rarely used. Hence, they have long names:</p></section><pre><code class="makeup erlang" translate="no"><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="7137889530-1">(</span><span class="p" data-group-id="7137889530-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="7137889530-2">(</span><span class="nf">any</span><span class="p" data-group-id="7137889530-3">(</span><span class="p" data-group-id="7137889530-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="7137889530-4">(</span><span class="p" data-group-id="7137889530-4">)</span><span class="p" data-group-id="7137889530-2">)</span><span class="w">
│ │ │ │ +</span><span class="nf">nonempty_improper_list</span><span class="p" data-group-id="7137889530-5">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="7137889530-5">)</span><span class="w">
│ │ │ │ +</span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="7137889530-6">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="7137889530-6">)</span></code></pre><p>where the last two types define the set of Erlang terms one would expect.</p><p>Also for convenience, record notation is allowed to be used. Records are
│ │ │ │ +shorthands for the corresponding tuples:</p><pre><code class="makeup erlang" translate="no"><span class="n">Record</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="4755949081-1">{</span><span class="p" data-group-id="4755949081-1">}</span><span class="w">
│ │ │ │ +        </span><span class="p">|</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="4755949081-2">{</span><span class="n">Fields</span><span class="p" data-group-id="4755949081-2">}</span></code></pre><p>Records are extended to possibly contain type information. This is described in
│ │ │ │  <a href="typespec.xhtml#typeinrecords">Type Information in Record Declarations</a>.</p><h3 id="redefining-built-in-types" class="section-heading">
│ │ │ │    <a href="#redefining-built-in-types" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Redefining built-in types</span>
│ │ │ │  </h3>
│ │ │ │  <section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Starting from Erlang/OTP 26, it is permitted to define a type having the same
│ │ │ │  name as a built-in type.</p></section><p>It is recommended to avoid deliberately reusing built-in names because it can be
│ │ │ │  confusing. However, when an Erlang/OTP release introduces a new type, code that
│ │ │ │  happened to define its own type having the same name will continue to work.</p><p>As an example, imagine that the Erlang/OTP 42 release introduces a new type
│ │ │ │ -<code class="inline">gadget()</code> defined like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="1818535219-1">(</span><span class="p" data-group-id="1818535219-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="1818535219-2">{</span><span class="ss">&#39;gadget&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">reference</span><span class="p" data-group-id="1818535219-3">(</span><span class="p" data-group-id="1818535219-3">)</span><span class="p" data-group-id="1818535219-2">}</span><span class="p">.</span></code></pre><p>Further imagine that some code has its own (different) definition of <code class="inline">gadget()</code>,
│ │ │ │ -for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="6195173616-1">(</span><span class="p" data-group-id="6195173616-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="6195173616-2">#{</span><span class="p" data-group-id="6195173616-2">}</span><span class="p">.</span></code></pre><p>Since redefinitions are allowed, the code will still compile (but with a
│ │ │ │ +<code class="inline">gadget()</code> defined like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="6164943164-1">(</span><span class="p" data-group-id="6164943164-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="6164943164-2">{</span><span class="ss">&#39;gadget&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">reference</span><span class="p" data-group-id="6164943164-3">(</span><span class="p" data-group-id="6164943164-3">)</span><span class="p" data-group-id="6164943164-2">}</span><span class="p">.</span></code></pre><p>Further imagine that some code has its own (different) definition of <code class="inline">gadget()</code>,
│ │ │ │ +for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="5925665565-1">(</span><span class="p" data-group-id="5925665565-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="5925665565-2">#{</span><span class="p" data-group-id="5925665565-2">}</span><span class="p">.</span></code></pre><p>Since redefinitions are allowed, the code will still compile (but with a
│ │ │ │  warning), and Dialyzer will not emit any additional warnings.</p><h2 id="type-declarations-of-user-defined-types" class="section-heading">
│ │ │ │    <a href="#type-declarations-of-user-defined-types" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Type Declarations of User-Defined Types</span>
│ │ │ │  </h2>
│ │ │ │  <p>As seen, the basic syntax of a type is an atom followed by closed parentheses.
│ │ │ │  New types are declared using <code class="inline">-type</code> and <code class="inline">-opaque</code> attributes as in the
│ │ │ │ -following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_struct_type</span><span class="p" data-group-id="7445536231-1">(</span><span class="p" data-group-id="7445536231-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">my_opaq_type</span><span class="p" data-group-id="7445536231-2">(</span><span class="p" data-group-id="7445536231-2">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span></code></pre><p>The type name is the atom <code class="inline">my_struct_type</code>, followed by parentheses. <code class="inline">Type</code> is a
│ │ │ │ +following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_struct_type</span><span class="p" data-group-id="9146374351-1">(</span><span class="p" data-group-id="9146374351-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">my_opaq_type</span><span class="p" data-group-id="9146374351-2">(</span><span class="p" data-group-id="9146374351-2">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span></code></pre><p>The type name is the atom <code class="inline">my_struct_type</code>, followed by parentheses. <code class="inline">Type</code> is a
│ │ │ │  type as defined in the previous section. A current restriction is that <code class="inline">Type</code>
│ │ │ │  can contain only predefined types, or user-defined types which are either of the
│ │ │ │  following:</p><ul><li>Module-local type, that is, with a definition that is present in the code of
│ │ │ │  the module</li><li>Remote type, that is, type defined in, and exported by, other modules; more
│ │ │ │  about this soon.</li></ul><p>For module-local types, the restriction that their definition exists in the
│ │ │ │  module is enforced by the compiler and results in a compilation error. (A
│ │ │ │  similar restriction currently exists for records.)</p><p>Type declarations can also be parameterized by including type variables between
│ │ │ │  the parentheses. The syntax of type variables is the same as Erlang variables,
│ │ │ │  that is, starts with an upper-case letter. These variables is to
│ │ │ │ -appear on the RHS of the definition. A concrete example follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">orddict</span><span class="p" data-group-id="8814575619-1">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="8814575619-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="8814575619-2">[</span><span class="p" data-group-id="8814575619-3">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="8814575619-3">}</span><span class="p" data-group-id="8814575619-2">]</span><span class="p">.</span></code></pre><p>A module can export some types to declare that other modules are allowed to
│ │ │ │ -refer to them as <em>remote types</em>. This declaration has the following form:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="9742779953-1">(</span><span class="p" data-group-id="9742779953-2">[</span><span class="n">T1</span><span class="o">/</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Tk</span><span class="o">/</span><span class="n">Ak</span><span class="p" data-group-id="9742779953-2">]</span><span class="p" data-group-id="9742779953-1">)</span><span class="p">.</span></code></pre><p>Here the <code class="inline">Ti</code>s are atoms (the name of the type) and the <code class="inline">Ai</code>s are their arguments.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="3687885992-1">(</span><span class="p" data-group-id="3687885992-2">[</span><span class="ss">my_struct_type</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">orddict</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3687885992-2">]</span><span class="p" data-group-id="3687885992-1">)</span><span class="p">.</span></code></pre><p>Assuming that these types are exported from module <code class="inline">'mod'</code>, you can refer to
│ │ │ │ -them from other modules using remote type expressions like the following:</p><pre><code class="makeup erlang" translate="no"><span class="nc">mod</span><span class="p">:</span><span class="nf">my_struct_type</span><span class="p" data-group-id="0293973916-1">(</span><span class="p" data-group-id="0293973916-1">)</span><span class="w">
│ │ │ │ -</span><span class="nc">mod</span><span class="p">:</span><span class="nf">orddict</span><span class="p" data-group-id="0293973916-2">(</span><span class="nf">atom</span><span class="p" data-group-id="0293973916-3">(</span><span class="p" data-group-id="0293973916-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0293973916-4">(</span><span class="p" data-group-id="0293973916-4">)</span><span class="p" data-group-id="0293973916-2">)</span></code></pre><p>It is not allowed to refer to types that are not declared as exported.</p><p>Types declared as <code class="inline">opaque</code> represent sets of terms whose structure is not
│ │ │ │ +appear on the RHS of the definition. A concrete example follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">orddict</span><span class="p" data-group-id="6235620509-1">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="6235620509-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="6235620509-2">[</span><span class="p" data-group-id="6235620509-3">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="6235620509-3">}</span><span class="p" data-group-id="6235620509-2">]</span><span class="p">.</span></code></pre><p>A module can export some types to declare that other modules are allowed to
│ │ │ │ +refer to them as <em>remote types</em>. This declaration has the following form:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="4621643489-1">(</span><span class="p" data-group-id="4621643489-2">[</span><span class="n">T1</span><span class="o">/</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Tk</span><span class="o">/</span><span class="n">Ak</span><span class="p" data-group-id="4621643489-2">]</span><span class="p" data-group-id="4621643489-1">)</span><span class="p">.</span></code></pre><p>Here the <code class="inline">Ti</code>s are atoms (the name of the type) and the <code class="inline">Ai</code>s are their arguments.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="4928938816-1">(</span><span class="p" data-group-id="4928938816-2">[</span><span class="ss">my_struct_type</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">orddict</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="4928938816-2">]</span><span class="p" data-group-id="4928938816-1">)</span><span class="p">.</span></code></pre><p>Assuming that these types are exported from module <code class="inline">'mod'</code>, you can refer to
│ │ │ │ +them from other modules using remote type expressions like the following:</p><pre><code class="makeup erlang" translate="no"><span class="nc">mod</span><span class="p">:</span><span class="nf">my_struct_type</span><span class="p" data-group-id="7060554891-1">(</span><span class="p" data-group-id="7060554891-1">)</span><span class="w">
│ │ │ │ +</span><span class="nc">mod</span><span class="p">:</span><span class="nf">orddict</span><span class="p" data-group-id="7060554891-2">(</span><span class="nf">atom</span><span class="p" data-group-id="7060554891-3">(</span><span class="p" data-group-id="7060554891-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="7060554891-4">(</span><span class="p" data-group-id="7060554891-4">)</span><span class="p" data-group-id="7060554891-2">)</span></code></pre><p>It is not allowed to refer to types that are not declared as exported.</p><p>Types declared as <code class="inline">opaque</code> represent sets of terms whose structure is not
│ │ │ │  supposed to be visible from outside of their defining module. That is, only the
│ │ │ │  module defining them is allowed to depend on their term structure. Consequently,
│ │ │ │  such types do not make much sense as module local - module local types are not
│ │ │ │  accessible by other modules anyway - and is always to be exported.</p><p>Read more on <a href="opaques.xhtml">Opaques</a></p><p><a href="" id="typeinrecords"></a></p><h2 id="type-information-in-record-declarations" class="section-heading">
│ │ │ │    <a href="#type-information-in-record-declarations" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Type Information in Record Declarations</span>
│ │ │ │  </h2>
│ │ │ │  <p>The types of record fields can be specified in the declaration of the record.
│ │ │ │ -The syntax for this is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2695727861-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2695727861-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="2695727861-2">}</span><span class="p" data-group-id="2695727861-1">)</span><span class="p">.</span></code></pre><p>For fields without type annotations, their type defaults to <code class="inline">any()</code>. That is, the
│ │ │ │ -previous example is a shorthand for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1749117036-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1749117036-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="1749117036-3">(</span><span class="p" data-group-id="1749117036-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="1749117036-2">}</span><span class="p" data-group-id="1749117036-1">)</span><span class="p">.</span></code></pre><p>In the presence of initial values for fields, the type must be declared after
│ │ │ │ -the initialization, as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9951078955-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9951078955-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9951078955-3">[</span><span class="p" data-group-id="9951078955-3">]</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="9951078955-2">}</span><span class="p" data-group-id="9951078955-1">)</span><span class="p">.</span></code></pre><p>The initial values for fields are to be compatible with (that is, a member of)
│ │ │ │ +The syntax for this is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9473510915-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9473510915-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="9473510915-2">}</span><span class="p" data-group-id="9473510915-1">)</span><span class="p">.</span></code></pre><p>For fields without type annotations, their type defaults to <code class="inline">any()</code>. That is, the
│ │ │ │ +previous example is a shorthand for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4700548945-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4700548945-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="4700548945-3">(</span><span class="p" data-group-id="4700548945-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="4700548945-2">}</span><span class="p" data-group-id="4700548945-1">)</span><span class="p">.</span></code></pre><p>In the presence of initial values for fields, the type must be declared after
│ │ │ │ +the initialization, as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3267335294-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3267335294-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3267335294-3">[</span><span class="p" data-group-id="3267335294-3">]</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="3267335294-2">}</span><span class="p" data-group-id="3267335294-1">)</span><span class="p">.</span></code></pre><p>The initial values for fields are to be compatible with (that is, a member of)
│ │ │ │  the corresponding types. This is checked by the compiler and results in a
│ │ │ │  compilation error if a violation is detected.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 19, for fields without initial values, the singleton type
│ │ │ │  <code class="inline">'undefined'</code> was added to all declared types. In other words, the following
│ │ │ │ -two record declarations had identical effects:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2431584174-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2431584174-2">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="2431584174-3">(</span><span class="p" data-group-id="2431584174-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="2431584174-4">(</span><span class="p" data-group-id="2431584174-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="2431584174-2">}</span><span class="p" data-group-id="2431584174-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +two record declarations had identical effects:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8905296487-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8905296487-2">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="8905296487-3">(</span><span class="p" data-group-id="8905296487-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="8905296487-4">(</span><span class="p" data-group-id="8905296487-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="8905296487-2">}</span><span class="p" data-group-id="8905296487-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2431584174-5">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2431584174-6">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="2431584174-7">(</span><span class="p" data-group-id="2431584174-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="2431584174-8">(</span><span class="p" data-group-id="2431584174-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="2431584174-6">}</span><span class="p" data-group-id="2431584174-5">)</span><span class="p">.</span></code></pre><p>This is no longer the case. If you require <code class="inline">'undefined'</code> in your record field
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8905296487-5">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8905296487-6">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="8905296487-7">(</span><span class="p" data-group-id="8905296487-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="8905296487-8">(</span><span class="p" data-group-id="8905296487-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="8905296487-6">}</span><span class="p" data-group-id="8905296487-5">)</span><span class="p">.</span></code></pre><p>This is no longer the case. If you require <code class="inline">'undefined'</code> in your record field
│ │ │ │  type, you must explicitly add it to the typespec, as in the 2nd example.</p></section><p>Any record, containing type information or not, once defined, can be used as a
│ │ │ │  type using the following syntax:</p><pre><code class="text">#rec{}</code></pre><p>In addition, the record fields can be further specified when using a record type
│ │ │ │  by adding type information about the field as follows:</p><pre><code class="text">#rec{some_field :: Type}</code></pre><p>Any unspecified fields are assumed to have the type in the original record
│ │ │ │  declaration.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>When records are used to create patterns for ETS and Mnesia match functions,
│ │ │ │ -Dialyzer may need some help not to emit bad warnings. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="7960365336-1">(</span><span class="p" data-group-id="7960365336-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="7960365336-2">(</span><span class="p" data-group-id="7960365336-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7960365336-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7960365336-4">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="7960365336-5">(</span><span class="p" data-group-id="7960365336-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="7960365336-6">(</span><span class="p" data-group-id="7960365336-6">)</span><span class="p" data-group-id="7960365336-4">}</span><span class="p" data-group-id="7960365336-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +Dialyzer may need some help not to emit bad warnings. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="3578796014-1">(</span><span class="p" data-group-id="3578796014-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="3578796014-2">(</span><span class="p" data-group-id="3578796014-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3578796014-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3578796014-4">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="3578796014-5">(</span><span class="p" data-group-id="3578796014-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="3578796014-6">(</span><span class="p" data-group-id="3578796014-6">)</span><span class="p" data-group-id="3578796014-4">}</span><span class="p" data-group-id="3578796014-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">lookup</span><span class="p" data-group-id="7960365336-7">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="7960365336-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="7960365336-8">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="7960365336-9">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="7960365336-9">}</span><span class="p" data-group-id="7960365336-8">)</span><span class="p">.</span></code></pre><p>Dialyzer will emit a warning since <code class="inline">'_'</code> is not in the type of record field
│ │ │ │ +</span><span class="nf">lookup</span><span class="p" data-group-id="3578796014-7">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="3578796014-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="3578796014-8">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3578796014-9">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="3578796014-9">}</span><span class="p" data-group-id="3578796014-8">)</span><span class="p">.</span></code></pre><p>Dialyzer will emit a warning since <code class="inline">'_'</code> is not in the type of record field
│ │ │ │  <code class="inline">height</code>.</p><p>The recommended way of dealing with this is to declare the smallest record
│ │ │ │  field types to accommodate all your needs, and then create refinements as
│ │ │ │ -needed. The modified example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9361821338-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9361821338-2">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="9361821338-3">(</span><span class="p" data-group-id="9361821338-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="9361821338-4">(</span><span class="p" data-group-id="9361821338-4">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="9361821338-2">}</span><span class="p" data-group-id="9361821338-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +needed. The modified example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3953534490-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3953534490-2">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="3953534490-3">(</span><span class="p" data-group-id="3953534490-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="3953534490-4">(</span><span class="p" data-group-id="3953534490-4">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="3953534490-2">}</span><span class="p" data-group-id="3953534490-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">person</span><span class="p" data-group-id="9361821338-5">(</span><span class="p" data-group-id="9361821338-5">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9361821338-6">{</span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="9361821338-7">(</span><span class="p" data-group-id="9361821338-7">)</span><span class="p" data-group-id="9361821338-6">}</span><span class="p">.</span></code></pre><p>In specifications and type declarations the type <code class="inline">person()</code> is to be preferred
│ │ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">person</span><span class="p" data-group-id="3953534490-5">(</span><span class="p" data-group-id="3953534490-5">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3953534490-6">{</span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="3953534490-7">(</span><span class="p" data-group-id="3953534490-7">)</span><span class="p" data-group-id="3953534490-6">}</span><span class="p">.</span></code></pre><p>In specifications and type declarations the type <code class="inline">person()</code> is to be preferred
│ │ │ │  before <code class="inline">#person{}</code>.</p></section><h2 id="specifications-for-functions" class="section-heading">
│ │ │ │    <a href="#specifications-for-functions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Specifications for Functions</span>
│ │ │ │  </h2>
│ │ │ │  <p>A specification (or contract) for a function is given using the <code class="inline">-spec</code>
│ │ │ │  attribute. The general format is as follows:</p><pre><code class="text">-spec Function(ArgType1, ..., ArgTypeN) -&gt; ReturnType.</code></pre><p>An implementation of the function with the same name <code class="inline">Function</code> must exist in
│ │ │ │  the current module, and the arity of the function must match the number of
│ │ │ │  arguments, otherwise the compilation fails.</p><p>The following longer format with module name is also valid as long as <code class="inline">Module</code>
│ │ │ │  is the name of the current module. This can be useful for documentation
│ │ │ │  purposes.</p><pre><code class="text">-spec Module:Function(ArgType1, ..., ArgTypeN) -&gt; ReturnType.</code></pre><p>Also, for documentation purposes, argument names can be given:</p><pre><code class="text">-spec Function(ArgName1 :: Type1, ..., ArgNameN :: TypeN) -&gt; RT.</code></pre><p>A function specification can be overloaded. That is, it can have several types,
│ │ │ │ -separated by a semicolon (<code class="inline">;</code>). For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="3045192804-1">(</span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="3045192804-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T3</span><span class="p">;</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="3045192804-2">(</span><span class="n">T4</span><span class="p">,</span><span class="w"> </span><span class="n">T5</span><span class="p" data-group-id="3045192804-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T6</span><span class="p">.</span></code></pre><p>A current restriction, which currently results in a warning by Dialyzer, is that
│ │ │ │ +separated by a semicolon (<code class="inline">;</code>). For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="5488518497-1">(</span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="5488518497-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T3</span><span class="p">;</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="5488518497-2">(</span><span class="n">T4</span><span class="p">,</span><span class="w"> </span><span class="n">T5</span><span class="p" data-group-id="5488518497-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T6</span><span class="p">.</span></code></pre><p>A current restriction, which currently results in a warning by Dialyzer, is that
│ │ │ │  the domains of the argument types cannot overlap. For example, the following
│ │ │ │ -specification results in a warning:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="2815672402-1">(</span><span class="nf">pos_integer</span><span class="p" data-group-id="2815672402-2">(</span><span class="p" data-group-id="2815672402-2">)</span><span class="p" data-group-id="2815672402-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="2815672402-3">(</span><span class="p" data-group-id="2815672402-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="2815672402-4">(</span><span class="nf">integer</span><span class="p" data-group-id="2815672402-5">(</span><span class="p" data-group-id="2815672402-5">)</span><span class="p" data-group-id="2815672402-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="2815672402-6">(</span><span class="p" data-group-id="2815672402-6">)</span><span class="p">.</span></code></pre><p>Type variables can be used in specifications to specify relations for the input
│ │ │ │ +specification results in a warning:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="4679016196-1">(</span><span class="nf">pos_integer</span><span class="p" data-group-id="4679016196-2">(</span><span class="p" data-group-id="4679016196-2">)</span><span class="p" data-group-id="4679016196-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="4679016196-3">(</span><span class="p" data-group-id="4679016196-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="4679016196-4">(</span><span class="nf">integer</span><span class="p" data-group-id="4679016196-5">(</span><span class="p" data-group-id="4679016196-5">)</span><span class="p" data-group-id="4679016196-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="4679016196-6">(</span><span class="p" data-group-id="4679016196-6">)</span><span class="p">.</span></code></pre><p>Type variables can be used in specifications to specify relations for the input
│ │ │ │  and output arguments of a function. For example, the following specification
│ │ │ │  defines the type of a polymorphic identity function:</p><pre><code class="text">-spec id(X) -&gt; X.</code></pre><p>Notice that the above specification does not restrict the input and output type
│ │ │ │  in any way. These types can be constrained by guard-like subtype constraints and
│ │ │ │ -provide bounded quantification:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="0200174162-1">(</span><span class="n">X</span><span class="p" data-group-id="0200174162-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="0200174162-2">(</span><span class="p" data-group-id="0200174162-2">)</span><span class="p">.</span></code></pre><p>Currently, the <code class="inline">::</code> constraint (read as &quot;is a subtype of&quot;) is the only guard
│ │ │ │ +provide bounded quantification:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="3370536155-1">(</span><span class="n">X</span><span class="p" data-group-id="3370536155-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="3370536155-2">(</span><span class="p" data-group-id="3370536155-2">)</span><span class="p">.</span></code></pre><p>Currently, the <code class="inline">::</code> constraint (read as &quot;is a subtype of&quot;) is the only guard
│ │ │ │  constraint that can be used in the <code class="inline">when</code> part of a <code class="inline">-spec</code> attribute.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The above function specification uses multiple occurrences of the same type
│ │ │ │  variable. That provides more type information than the following function
│ │ │ │ -specification, where the type variables are missing:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="9261342357-1">(</span><span class="nf">tuple</span><span class="p" data-group-id="9261342357-2">(</span><span class="p" data-group-id="9261342357-2">)</span><span class="p" data-group-id="9261342357-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="9261342357-3">(</span><span class="p" data-group-id="9261342357-3">)</span><span class="p">.</span></code></pre><p>The latter specification says that the function takes some tuple and returns
│ │ │ │ +specification, where the type variables are missing:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="5648733609-1">(</span><span class="nf">tuple</span><span class="p" data-group-id="5648733609-2">(</span><span class="p" data-group-id="5648733609-2">)</span><span class="p" data-group-id="5648733609-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="5648733609-3">(</span><span class="p" data-group-id="5648733609-3">)</span><span class="p">.</span></code></pre><p>The latter specification says that the function takes some tuple and returns
│ │ │ │  some tuple. The specification with the <code class="inline">X</code> type variable specifies that the
│ │ │ │  function takes a tuple and returns <em>the same</em> tuple.</p><p>However, it is up to the tools that process the specifications to choose
│ │ │ │  whether to take this extra information into account or not.</p></section><p>The scope of a <code class="inline">::</code> constraint is the <code class="inline">(...) -&gt; RetType</code> specification after
│ │ │ │  which it appears. To avoid confusion, it is suggested that different variables
│ │ │ │  are used in different constituents of an overloaded contract, as shown in the
│ │ │ │ -following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="0419516235-1">(</span><span class="p" data-group-id="0419516235-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="0419516235-3">(</span><span class="p" data-group-id="0419516235-3">)</span><span class="p" data-group-id="0419516235-2">}</span><span class="p" data-group-id="0419516235-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="0419516235-4">(</span><span class="p" data-group-id="0419516235-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="0419516235-5">(</span><span class="p" data-group-id="0419516235-6">[</span><span class="n">Y</span><span class="p" data-group-id="0419516235-6">]</span><span class="p" data-group-id="0419516235-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="0419516235-7">(</span><span class="p" data-group-id="0419516235-7">)</span><span class="p">.</span></code></pre><p>Some functions in Erlang are not meant to return; either because they define
│ │ │ │ +following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="3784827185-1">(</span><span class="p" data-group-id="3784827185-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="3784827185-3">(</span><span class="p" data-group-id="3784827185-3">)</span><span class="p" data-group-id="3784827185-2">}</span><span class="p" data-group-id="3784827185-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="3784827185-4">(</span><span class="p" data-group-id="3784827185-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="3784827185-5">(</span><span class="p" data-group-id="3784827185-6">[</span><span class="n">Y</span><span class="p" data-group-id="3784827185-6">]</span><span class="p" data-group-id="3784827185-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3784827185-7">(</span><span class="p" data-group-id="3784827185-7">)</span><span class="p">.</span></code></pre><p>Some functions in Erlang are not meant to return; either because they define
│ │ │ │  servers or because they are used to throw exceptions, as in the following
│ │ │ │ -function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_error</span><span class="p" data-group-id="1933766309-1">(</span><span class="n">Err</span><span class="p" data-group-id="1933766309-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="1933766309-2">(</span><span class="p" data-group-id="1933766309-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Err</span><span class="p" data-group-id="1933766309-3">}</span><span class="p" data-group-id="1933766309-2">)</span><span class="p">.</span></code></pre><p>For such functions, it is recommended to use the special <a href="../../../lib/../erts/doc/html/erlang.html#t:no_return/0"><code class="inline">no_return/0</code></a> type
│ │ │ │ +function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_error</span><span class="p" data-group-id="9914738645-1">(</span><span class="n">Err</span><span class="p" data-group-id="9914738645-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="9914738645-2">(</span><span class="p" data-group-id="9914738645-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Err</span><span class="p" data-group-id="9914738645-3">}</span><span class="p" data-group-id="9914738645-2">)</span><span class="p">.</span></code></pre><p>For such functions, it is recommended to use the special <a href="../../../lib/../erts/doc/html/erlang.html#t:no_return/0"><code class="inline">no_return/0</code></a> type
│ │ │ │  for their &quot;return&quot;, through a contract of the following form:</p><pre><code class="text">-spec my_error(term()) -&gt; no_return().</code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Erlang uses the shorthand version <code class="inline">_</code> as an anonymous type variable equivalent
│ │ │ │  to <a href="../../../lib/../erts/doc/html/erlang.html#t:term/0"><code class="inline">term/0</code></a> or <a href="../../../lib/../erts/doc/html/erlang.html#t:any/0"><code class="inline">any/0</code></a>. For example, the following function</p><pre><code class="text">-spec Function(string(), _) -&gt; string().</code></pre><p>is equivalent to:</p><pre><code class="text">-spec Function(string(), any()) -&gt; string().</code></pre></section>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/tablesdatabases.xhtml
│ │ │ │ @@ -51,73 +51,73 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Deleting an Element</span>
│ │ │ │  </h3>
│ │ │ │  <p>The <code class="inline">delete</code> operation is considered successful if the element was not present
│ │ │ │  in the table. Hence all attempts to check that the element is present in the
│ │ │ │  Ets/Mnesia table before deletion are unnecessary. Here follows an example for
│ │ │ │ -Ets tables:</p><p><strong>DO</strong></p><pre><code class="text">ets:delete(Tab, Key),</code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="5301437458-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="5301437458-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5301437458-2">[</span><span class="p" data-group-id="5301437458-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +Ets tables:</p><p><strong>DO</strong></p><pre><code class="text">ets:delete(Tab, Key),</code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="7907253336-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="7907253336-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7907253336-2">[</span><span class="p" data-group-id="7907253336-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5301437458-3">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="5301437458-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nc">ets</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="5301437458-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="5301437458-4">)</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7907253336-3">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="7907253336-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nc">ets</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="7907253336-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="7907253336-4">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">,</span></code></pre><h3 id="fetching-data" class="section-heading">
│ │ │ │    <a href="#fetching-data" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Fetching Data</span>
│ │ │ │  </h3>
│ │ │ │  <p>Do not fetch data that you already have.</p><p>Consider that you have a module that handles the abstract data type <code class="inline">Person</code>.
│ │ │ │  You export the interface function <code class="inline">print_person/1</code>, which uses the internal
│ │ │ │  functions <code class="inline">print_name/1</code>, <code class="inline">print_age/1</code>, and <code class="inline">print_occupation/1</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>If the function <code class="inline">print_name/1</code>, and so on, had been interface functions, the
│ │ │ │  situation would have been different, as you do not want the user of the
│ │ │ │  interface to know about the internal data representation.</p></section><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Interface function</span><span class="w">
│ │ │ │ -</span><span class="nf">print_person</span><span class="p" data-group-id="9859767733-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="9859767733-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">print_person</span><span class="p" data-group-id="8121157912-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="8121157912-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Look up the person in the named table person,</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="9859767733-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="9859767733-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="9859767733-3">[</span><span class="n">Person</span><span class="p" data-group-id="9859767733-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">print_name</span><span class="p" data-group-id="9859767733-4">(</span><span class="n">Person</span><span class="p" data-group-id="9859767733-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">print_age</span><span class="p" data-group-id="9859767733-5">(</span><span class="n">Person</span><span class="p" data-group-id="9859767733-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">print_occupation</span><span class="p" data-group-id="9859767733-6">(</span><span class="n">Person</span><span class="p" data-group-id="9859767733-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="9859767733-7">[</span><span class="p" data-group-id="9859767733-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9859767733-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9859767733-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="9859767733-9">]</span><span class="p" data-group-id="9859767733-8">)</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="8121157912-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="8121157912-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8121157912-3">[</span><span class="n">Person</span><span class="p" data-group-id="8121157912-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">print_name</span><span class="p" data-group-id="8121157912-4">(</span><span class="n">Person</span><span class="p" data-group-id="8121157912-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">print_age</span><span class="p" data-group-id="8121157912-5">(</span><span class="n">Person</span><span class="p" data-group-id="8121157912-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">print_occupation</span><span class="p" data-group-id="8121157912-6">(</span><span class="n">Person</span><span class="p" data-group-id="8121157912-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8121157912-7">[</span><span class="p" data-group-id="8121157912-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8121157912-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8121157912-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="8121157912-9">]</span><span class="p" data-group-id="8121157912-8">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Internal functions</span><span class="w">
│ │ │ │ -</span><span class="nf">print_name</span><span class="p" data-group-id="9859767733-10">(</span><span class="n">Person</span><span class="p" data-group-id="9859767733-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9859767733-11">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9859767733-12">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="9859767733-12">]</span><span class="p" data-group-id="9859767733-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">print_name</span><span class="p" data-group-id="8121157912-10">(</span><span class="n">Person</span><span class="p" data-group-id="8121157912-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8121157912-11">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8121157912-12">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="8121157912-12">]</span><span class="p" data-group-id="8121157912-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">print_age</span><span class="p" data-group-id="9859767733-13">(</span><span class="n">Person</span><span class="p" data-group-id="9859767733-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9859767733-14">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9859767733-15">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="9859767733-15">]</span><span class="p" data-group-id="9859767733-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">print_age</span><span class="p" data-group-id="8121157912-13">(</span><span class="n">Person</span><span class="p" data-group-id="8121157912-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8121157912-14">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8121157912-15">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="8121157912-15">]</span><span class="p" data-group-id="8121157912-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">print_occupation</span><span class="p" data-group-id="9859767733-16">(</span><span class="n">Person</span><span class="p" data-group-id="9859767733-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9859767733-17">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9859767733-18">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="9859767733-18">]</span><span class="p" data-group-id="9859767733-17">)</span><span class="p">.</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Interface function</span><span class="w">
│ │ │ │ -</span><span class="nf">print_person</span><span class="p" data-group-id="6029297231-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="6029297231-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">print_occupation</span><span class="p" data-group-id="8121157912-16">(</span><span class="n">Person</span><span class="p" data-group-id="8121157912-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8121157912-17">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8121157912-18">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="8121157912-18">]</span><span class="p" data-group-id="8121157912-17">)</span><span class="p">.</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Interface function</span><span class="w">
│ │ │ │ +</span><span class="nf">print_person</span><span class="p" data-group-id="3958917802-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="3958917802-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Look up the person in the named table person,</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="6029297231-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="6029297231-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6029297231-3">[</span><span class="n">Person</span><span class="p" data-group-id="6029297231-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">print_name</span><span class="p" data-group-id="6029297231-4">(</span><span class="n">PersonID</span><span class="p" data-group-id="6029297231-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">print_age</span><span class="p" data-group-id="6029297231-5">(</span><span class="n">PersonID</span><span class="p" data-group-id="6029297231-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">print_occupation</span><span class="p" data-group-id="6029297231-6">(</span><span class="n">PersonID</span><span class="p" data-group-id="6029297231-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6029297231-7">[</span><span class="p" data-group-id="6029297231-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6029297231-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6029297231-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="6029297231-9">]</span><span class="p" data-group-id="6029297231-8">)</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3958917802-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="3958917802-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="3958917802-3">[</span><span class="n">Person</span><span class="p" data-group-id="3958917802-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">print_name</span><span class="p" data-group-id="3958917802-4">(</span><span class="n">PersonID</span><span class="p" data-group-id="3958917802-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">print_age</span><span class="p" data-group-id="3958917802-5">(</span><span class="n">PersonID</span><span class="p" data-group-id="3958917802-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">print_occupation</span><span class="p" data-group-id="3958917802-6">(</span><span class="n">PersonID</span><span class="p" data-group-id="3958917802-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="3958917802-7">[</span><span class="p" data-group-id="3958917802-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3958917802-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3958917802-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="3958917802-9">]</span><span class="p" data-group-id="3958917802-8">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Internal functions</span><span class="w">
│ │ │ │ -</span><span class="nf">print_name</span><span class="p" data-group-id="6029297231-10">(</span><span class="n">PersonID</span><span class="p" data-group-id="6029297231-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6029297231-11">[</span><span class="n">Person</span><span class="p" data-group-id="6029297231-11">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="6029297231-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="6029297231-12">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6029297231-13">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6029297231-14">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="6029297231-14">]</span><span class="p" data-group-id="6029297231-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">print_age</span><span class="p" data-group-id="6029297231-15">(</span><span class="n">PersonID</span><span class="p" data-group-id="6029297231-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6029297231-16">[</span><span class="n">Person</span><span class="p" data-group-id="6029297231-16">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="6029297231-17">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="6029297231-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6029297231-18">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6029297231-19">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="6029297231-19">]</span><span class="p" data-group-id="6029297231-18">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">print_occupation</span><span class="p" data-group-id="6029297231-20">(</span><span class="n">PersonID</span><span class="p" data-group-id="6029297231-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6029297231-21">[</span><span class="n">Person</span><span class="p" data-group-id="6029297231-21">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="6029297231-22">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="6029297231-22">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6029297231-23">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6029297231-24">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="6029297231-24">]</span><span class="p" data-group-id="6029297231-23">)</span><span class="p">.</span></code></pre><h3 id="non-persistent-database-storage" class="section-heading">
│ │ │ │ +</span><span class="nf">print_name</span><span class="p" data-group-id="3958917802-10">(</span><span class="n">PersonID</span><span class="p" data-group-id="3958917802-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3958917802-11">[</span><span class="n">Person</span><span class="p" data-group-id="3958917802-11">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3958917802-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="3958917802-12">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3958917802-13">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3958917802-14">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="3958917802-14">]</span><span class="p" data-group-id="3958917802-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">print_age</span><span class="p" data-group-id="3958917802-15">(</span><span class="n">PersonID</span><span class="p" data-group-id="3958917802-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3958917802-16">[</span><span class="n">Person</span><span class="p" data-group-id="3958917802-16">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3958917802-17">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="3958917802-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3958917802-18">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3958917802-19">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="3958917802-19">]</span><span class="p" data-group-id="3958917802-18">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">print_occupation</span><span class="p" data-group-id="3958917802-20">(</span><span class="n">PersonID</span><span class="p" data-group-id="3958917802-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3958917802-21">[</span><span class="n">Person</span><span class="p" data-group-id="3958917802-21">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3958917802-22">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="3958917802-22">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3958917802-23">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3958917802-24">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="3958917802-24">]</span><span class="p" data-group-id="3958917802-23">)</span><span class="p">.</span></code></pre><h3 id="non-persistent-database-storage" class="section-heading">
│ │ │ │    <a href="#non-persistent-database-storage" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Non-Persistent Database Storage</span>
│ │ │ │  </h3>
│ │ │ │  <p>For non-persistent database storage, prefer Ets tables over Mnesia
│ │ │ │  <code class="inline">local_content</code> tables. Even the Mnesia <code class="inline">dirty_write</code> operations carry a fixed
│ │ │ │ @@ -131,38 +131,38 @@
│ │ │ │  </h3>
│ │ │ │  <p>Assuming an Ets table that uses <code class="inline">idno</code> as key and contains the following:</p><pre><code class="text">[#person{idno = 1, name = &quot;Adam&quot;,  age = 31, occupation = &quot;mailman&quot;},
│ │ │ │   #person{idno = 2, name = &quot;Bryan&quot;, age = 31, occupation = &quot;cashier&quot;},
│ │ │ │   #person{idno = 3, name = &quot;Bryan&quot;, age = 35, occupation = &quot;banker&quot;},
│ │ │ │   #person{idno = 4, name = &quot;Carl&quot;,  age = 25, occupation = &quot;mailman&quot;}]</code></pre><p>If you <em>must</em> return all data stored in the Ets table, you can use
│ │ │ │  <a href="../../../lib/stdlib/doc/html/ets.html#tab2list/1"><code class="inline">ets:tab2list/1</code></a>. However, usually you are only interested in a subset of the
│ │ │ │  information in which case <a href="../../../lib/stdlib/doc/html/ets.html#tab2list/1"><code class="inline">ets:tab2list/1</code></a> is expensive. If you only want to
│ │ │ │ -extract one field from each record, for example, the age of every person, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="2470225638-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2470225638-2">[</span><span class="p" data-group-id="2470225638-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2470225638-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │ +extract one field from each record, for example, the age of every person, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="7866943958-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7866943958-2">[</span><span class="p" data-group-id="7866943958-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="7866943958-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │                            </span><span class="ss">name</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │                            </span><span class="ss">age</span><span class="o">=</span><span class="ss">&#39;$1&#39;</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="2470225638-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                </span><span class="p" data-group-id="2470225638-5">[</span><span class="p" data-group-id="2470225638-5">]</span><span class="p">,</span><span class="w">
│ │ │ │ -                </span><span class="p" data-group-id="2470225638-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="2470225638-6">]</span><span class="p" data-group-id="2470225638-3">}</span><span class="p" data-group-id="2470225638-2">]</span><span class="p" data-group-id="2470225638-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="1105956800-1">(</span><span class="n">Tab</span><span class="p" data-group-id="1105956800-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="1105956800-2">(</span><span class="nf">fun</span><span class="p" data-group-id="1105956800-3">(</span><span class="n">X</span><span class="p" data-group-id="1105956800-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="1105956800-2">)</span><span class="p">,</span></code></pre><p>If you are only interested in the age of all persons named &quot;Bryan&quot;, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="8069814822-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8069814822-2">[</span><span class="p" data-group-id="8069814822-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="8069814822-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │ +                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="7866943958-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="p" data-group-id="7866943958-5">[</span><span class="p" data-group-id="7866943958-5">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="p" data-group-id="7866943958-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="7866943958-6">]</span><span class="p" data-group-id="7866943958-3">}</span><span class="p" data-group-id="7866943958-2">]</span><span class="p" data-group-id="7866943958-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="6419492278-1">(</span><span class="n">Tab</span><span class="p" data-group-id="6419492278-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="6419492278-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6419492278-3">(</span><span class="n">X</span><span class="p" data-group-id="6419492278-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="6419492278-2">)</span><span class="p">,</span></code></pre><p>If you are only interested in the age of all persons named &quot;Bryan&quot;, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="0043281212-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0043281212-2">[</span><span class="p" data-group-id="0043281212-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0043281212-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │                            </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Bryan&quot;</span><span class="p">,</span><span class="w">
│ │ │ │                            </span><span class="ss">age</span><span class="o">=</span><span class="ss">&#39;$1&#39;</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="8069814822-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                </span><span class="p" data-group-id="8069814822-5">[</span><span class="p" data-group-id="8069814822-5">]</span><span class="p">,</span><span class="w">
│ │ │ │ -                </span><span class="p" data-group-id="8069814822-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="8069814822-6">]</span><span class="p" data-group-id="8069814822-3">}</span><span class="p" data-group-id="8069814822-2">]</span><span class="p" data-group-id="8069814822-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="7475634034-1">(</span><span class="n">Tab</span><span class="p" data-group-id="7475634034-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="7475634034-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7475634034-3">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7475634034-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="0043281212-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="p" data-group-id="0043281212-5">[</span><span class="p" data-group-id="0043281212-5">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="p" data-group-id="0043281212-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="0043281212-6">]</span><span class="p" data-group-id="0043281212-3">}</span><span class="p" data-group-id="0043281212-2">]</span><span class="p" data-group-id="0043281212-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="3639705452-1">(</span><span class="n">Tab</span><span class="p" data-group-id="3639705452-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="3639705452-2">(</span><span class="nf">fun</span><span class="p" data-group-id="3639705452-3">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3639705452-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │                                  </span><span class="s">&quot;Bryan&quot;</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                                    </span><span class="p" data-group-id="7475634034-4">[</span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="7475634034-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ +                                    </span><span class="p" data-group-id="3639705452-4">[</span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="3639705452-4">]</span><span class="p">;</span><span class="w">
│ │ │ │                                   </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                                       </span><span class="n">Acc</span><span class="w">
│ │ │ │                             </span><span class="k">end</span><span class="w">
│ │ │ │ -             </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7475634034-5">[</span><span class="p" data-group-id="7475634034-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="7475634034-2">)</span></code></pre><p>If you need all information stored in the Ets table about persons named &quot;Bryan&quot;,
│ │ │ │ -then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="5799258647-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5799258647-2">[</span><span class="p" data-group-id="5799258647-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5799258647-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3639705452-5">[</span><span class="p" data-group-id="3639705452-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="3639705452-2">)</span></code></pre><p>If you need all information stored in the Ets table about persons named &quot;Bryan&quot;,
│ │ │ │ +then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="7189356889-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7189356889-2">[</span><span class="p" data-group-id="7189356889-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="7189356889-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │                            </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Bryan&quot;</span><span class="p">,</span><span class="w">
│ │ │ │                            </span><span class="ss">age</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="5799258647-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5799258647-5">[</span><span class="p" data-group-id="5799258647-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5799258647-6">[</span><span class="ss">&#39;$_&#39;</span><span class="p" data-group-id="5799258647-6">]</span><span class="p" data-group-id="5799258647-3">}</span><span class="p" data-group-id="5799258647-2">]</span><span class="p" data-group-id="5799258647-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="7370799665-1">(</span><span class="n">Tab</span><span class="p" data-group-id="7370799665-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="7370799665-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7370799665-3">(</span><span class="n">X</span><span class="p" data-group-id="7370799665-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="s">&quot;Bryan&quot;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="7370799665-2">)</span><span class="p">,</span></code></pre><h3 id="ordered_set-tables" class="section-heading">
│ │ │ │ +                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="7189356889-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7189356889-5">[</span><span class="p" data-group-id="7189356889-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7189356889-6">[</span><span class="ss">&#39;$_&#39;</span><span class="p" data-group-id="7189356889-6">]</span><span class="p" data-group-id="7189356889-3">}</span><span class="p" data-group-id="7189356889-2">]</span><span class="p" data-group-id="7189356889-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="2214054354-1">(</span><span class="n">Tab</span><span class="p" data-group-id="2214054354-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="2214054354-2">(</span><span class="nf">fun</span><span class="p" data-group-id="2214054354-3">(</span><span class="n">X</span><span class="p" data-group-id="2214054354-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="s">&quot;Bryan&quot;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="2214054354-2">)</span><span class="p">,</span></code></pre><h3 id="ordered_set-tables" class="section-heading">
│ │ │ │    <a href="#ordered_set-tables" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text"><code class="inline">ordered_set</code> Tables</span>
│ │ │ │  </h3>
│ │ │ │  <p>If the data in the table is to be accessed so that the order of the keys in the
│ │ │ │  table is significant, the table type <code class="inline">ordered_set</code> can be used instead of the
│ │ │ │ @@ -198,20 +198,20 @@
│ │ │ │  Clearly, the second table would have to be kept consistent with the master
│ │ │ │  table. Mnesia can do this for you, but a home-brew index table can be very
│ │ │ │  efficient compared to the overhead involved in using Mnesia.</p><p>An index table for the table in the previous examples would have to be a bag (as
│ │ │ │  keys would appear more than once) and can have the following contents:</p><pre><code class="text">[#index_entry{name=&quot;Adam&quot;, idno=1},
│ │ │ │   #index_entry{name=&quot;Bryan&quot;, idno=2},
│ │ │ │   #index_entry{name=&quot;Bryan&quot;, idno=3},
│ │ │ │   #index_entry{name=&quot;Carl&quot;, idno=4}]</code></pre><p>Given this index table, a lookup of the <code class="inline">age</code> fields for all persons named
│ │ │ │ -&quot;Bryan&quot; can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">MatchingIDs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="7628386114-1">(</span><span class="n">IndexTable</span><span class="p">,</span><span class="s">&quot;Bryan&quot;</span><span class="p" data-group-id="7628386114-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="7628386114-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7628386114-3">(</span><span class="o">#</span><span class="ss">index_entry</span><span class="p" data-group-id="7628386114-4">{</span><span class="ss">idno</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="7628386114-4">}</span><span class="p" data-group-id="7628386114-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                 </span><span class="p" data-group-id="7628386114-5">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="7628386114-6">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="7628386114-6">}</span><span class="p" data-group-id="7628386114-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="7628386114-7">(</span><span class="n">PersonTable</span><span class="p">,</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="7628386114-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +&quot;Bryan&quot; can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">MatchingIDs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3793545590-1">(</span><span class="n">IndexTable</span><span class="p">,</span><span class="s">&quot;Bryan&quot;</span><span class="p" data-group-id="3793545590-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="3793545590-2">(</span><span class="nf">fun</span><span class="p" data-group-id="3793545590-3">(</span><span class="o">#</span><span class="ss">index_entry</span><span class="p" data-group-id="3793545590-4">{</span><span class="ss">idno</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="3793545590-4">}</span><span class="p" data-group-id="3793545590-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                 </span><span class="p" data-group-id="3793545590-5">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3793545590-6">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="3793545590-6">}</span><span class="p" data-group-id="3793545590-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3793545590-7">(</span><span class="n">PersonTable</span><span class="p">,</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="3793545590-7">)</span><span class="p">,</span><span class="w">
│ │ │ │                   </span><span class="n">Age</span><span class="w">
│ │ │ │            </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -          </span><span class="n">MatchingIDs</span><span class="p" data-group-id="7628386114-2">)</span><span class="p">,</span></code></pre><p>Notice that this code does not use <a href="../../../lib/stdlib/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a>, but instead uses the
│ │ │ │ +          </span><span class="n">MatchingIDs</span><span class="p" data-group-id="3793545590-2">)</span><span class="p">,</span></code></pre><p>Notice that this code does not use <a href="../../../lib/stdlib/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a>, but instead uses the
│ │ │ │  <a href="../../../lib/stdlib/doc/html/ets.html#lookup/2"><code class="inline">ets:lookup/2</code></a> call. The <a href="../../../lib/stdlib/doc/html/lists.html#map/2"><code class="inline">lists:map/2</code></a> call is only used to traverse the <code class="inline">idno</code>s
│ │ │ │  matching the name &quot;Bryan&quot; in the table; thus the number of lookups in the master
│ │ │ │  table is minimized.</p><p>Keeping an index table introduces some overhead when inserting records in the
│ │ │ │  table. The number of operations gained from the table must therefore be compared
│ │ │ │  against the number of operations inserting objects in the table. However, notice
│ │ │ │  that the gain is significant when the key can be used to lookup elements.</p><h2 id="mnesia" class="section-heading">
│ │ │ │    <a href="#mnesia" class="hover-link">
│ │ │ │ @@ -226,47 +226,47 @@
│ │ │ │    <span class="text">Secondary Index</span>
│ │ │ │  </h3>
│ │ │ │  <p>If you frequently do lookups on a field that is not the key of the table, you
│ │ │ │  lose performance using <a href="../../../lib/mnesia/doc/html/mnesia.html#select/3">mnesia:select()</a> or
│ │ │ │  <a href="../../../lib/mnesia/doc/html/mnesia.html#match_object/1"><code class="inline">mnesia:match_object()</code></a> as these function traverse
│ │ │ │  the whole table. Instead, you can create a secondary index and use
│ │ │ │  <a href="../../../lib/mnesia/doc/html/mnesia.html#index_read/3"><code class="inline">mnesia:index_read/3</code></a> to get faster access at the expense of using more
│ │ │ │ -memory.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5529871591-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5529871591-2">{</span><span class="ss">idno</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">occupation</span><span class="p" data-group-id="5529871591-2">}</span><span class="p" data-group-id="5529871591-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +memory.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6479205446-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6479205446-2">{</span><span class="ss">idno</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">occupation</span><span class="p" data-group-id="6479205446-2">}</span><span class="p" data-group-id="6479205446-1">)</span><span class="p">.</span><span class="w">
│ │ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5529871591-3">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="5529871591-3">}</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │ -</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">create_table</span><span class="p" data-group-id="5529871591-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5529871591-5">[</span><span class="p" data-group-id="5529871591-6">{</span><span class="ss">index</span><span class="p">,</span><span class="p" data-group-id="5529871591-7">[</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="5529871591-7">]</span><span class="p" data-group-id="5529871591-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                              </span><span class="p" data-group-id="5529871591-8">{</span><span class="ss">attributes</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="nf">record_info</span><span class="p" data-group-id="5529871591-9">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="5529871591-9">)</span><span class="p" data-group-id="5529871591-8">}</span><span class="p" data-group-id="5529871591-5">]</span><span class="p" data-group-id="5529871591-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5529871591-10">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="5529871591-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">add_table_index</span><span class="p" data-group-id="5529871591-11">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="5529871591-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6479205446-3">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="6479205446-3">}</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │ +</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">create_table</span><span class="p" data-group-id="6479205446-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6479205446-5">[</span><span class="p" data-group-id="6479205446-6">{</span><span class="ss">index</span><span class="p">,</span><span class="p" data-group-id="6479205446-7">[</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="6479205446-7">]</span><span class="p" data-group-id="6479205446-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                              </span><span class="p" data-group-id="6479205446-8">{</span><span class="ss">attributes</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="nf">record_info</span><span class="p" data-group-id="6479205446-9">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="6479205446-9">)</span><span class="p" data-group-id="6479205446-8">}</span><span class="p" data-group-id="6479205446-5">]</span><span class="p" data-group-id="6479205446-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6479205446-10">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="6479205446-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">add_table_index</span><span class="p" data-group-id="6479205446-11">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="6479205446-11">)</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="n">PersonsAge42</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │ -     </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_index_read</span><span class="p" data-group-id="5529871591-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="5529871591-12">)</span><span class="p">,</span></code></pre><h3 id="transactions" class="section-heading">
│ │ │ │ +     </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_index_read</span><span class="p" data-group-id="6479205446-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="6479205446-12">)</span><span class="p">,</span></code></pre><h3 id="transactions" class="section-heading">
│ │ │ │    <a href="#transactions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Transactions</span>
│ │ │ │  </h3>
│ │ │ │  <p>Using transactions is a way to guarantee that the distributed Mnesia database
│ │ │ │  remains consistent, even when many different processes update it in parallel.
│ │ │ │  However, if you have real-time requirements it is recommended to use dirtry
│ │ │ │  operations instead of transactions. When using dirty operations, you lose the
│ │ │ │  consistency guarantee; this is usually solved by only letting one process update
│ │ │ │  the table. Other processes must send update requests to that process.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% Using transaction</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="5607869458-1">(</span><span class="p" data-group-id="5607869458-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -          </span><span class="p" data-group-id="5607869458-2">[</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="5607869458-3">(</span><span class="p" data-group-id="5607869458-4">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="5607869458-4">}</span><span class="p" data-group-id="5607869458-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -           </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="5607869458-5">(</span><span class="p" data-group-id="5607869458-6">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="5607869458-6">}</span><span class="p" data-group-id="5607869458-5">)</span><span class="p" data-group-id="5607869458-2">]</span><span class="w">
│ │ │ │ +</span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="6772346590-1">(</span><span class="p" data-group-id="6772346590-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +          </span><span class="p" data-group-id="6772346590-2">[</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="6772346590-3">(</span><span class="p" data-group-id="6772346590-4">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="6772346590-4">}</span><span class="p" data-group-id="6772346590-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +           </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="6772346590-5">(</span><span class="p" data-group-id="6772346590-6">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="6772346590-6">}</span><span class="p" data-group-id="6772346590-5">)</span><span class="p" data-group-id="6772346590-2">]</span><span class="w">
│ │ │ │        </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="p" data-group-id="5607869458-7">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5607869458-8">[</span><span class="n">Result1</span><span class="p">,</span><span class="w"> </span><span class="n">Result2</span><span class="p" data-group-id="5607869458-8">]</span><span class="p" data-group-id="5607869458-7">}</span><span class="w">  </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">transaction</span><span class="p" data-group-id="5607869458-9">(</span><span class="n">Fun</span><span class="p" data-group-id="5607869458-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6772346590-7">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6772346590-8">[</span><span class="n">Result1</span><span class="p">,</span><span class="w"> </span><span class="n">Result2</span><span class="p" data-group-id="6772346590-8">]</span><span class="p" data-group-id="6772346590-7">}</span><span class="w">  </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">transaction</span><span class="p" data-group-id="6772346590-9">(</span><span class="n">Fun</span><span class="p" data-group-id="6772346590-9">)</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% Same thing using dirty operations</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Result1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="5607869458-10">(</span><span class="p" data-group-id="5607869458-11">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="5607869458-11">}</span><span class="p" data-group-id="5607869458-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Result2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="5607869458-12">(</span><span class="p" data-group-id="5607869458-13">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="5607869458-13">}</span><span class="p" data-group-id="5607869458-12">)</span><span class="p">,</span></code></pre>
│ │ │ │ +</span><span class="n">Result1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="6772346590-10">(</span><span class="p" data-group-id="6772346590-11">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="6772346590-11">}</span><span class="p" data-group-id="6772346590-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Result2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="6772346590-12">(</span><span class="p" data-group-id="6772346590-13">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="6772346590-13">}</span><span class="p" data-group-id="6772346590-12">)</span><span class="p">,</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/sup_princ.xhtml
│ │ │ │ @@ -33,48 +33,48 @@
│ │ │ │  the order specified by this list, and are terminated in the reverse order.</p><h2 id="example" class="section-heading">
│ │ │ │    <a href="#example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Example</span>
│ │ │ │  </h2>
│ │ │ │  <p>The callback module for a supervisor starting the server from
│ │ │ │ -<a href="gen_server_concepts.xhtml#ex">gen_server Behaviour</a> can look as follows:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6825130356-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="6825130356-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="6825130356-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="6825130356-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<a href="gen_server_concepts.xhtml#ex">gen_server Behaviour</a> can look as follows:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0182771507-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="0182771507-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="0182771507-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="0182771507-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6825130356-3">(</span><span class="p" data-group-id="6825130356-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6825130356-4">]</span><span class="p" data-group-id="6825130356-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6825130356-5">(</span><span class="p" data-group-id="6825130356-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6825130356-6">]</span><span class="p" data-group-id="6825130356-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0182771507-3">(</span><span class="p" data-group-id="0182771507-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0182771507-4">]</span><span class="p" data-group-id="0182771507-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0182771507-5">(</span><span class="p" data-group-id="0182771507-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0182771507-6">]</span><span class="p" data-group-id="0182771507-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="6825130356-7">(</span><span class="p" data-group-id="6825130356-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="6825130356-8">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6825130356-9">[</span><span class="p" data-group-id="6825130356-9">]</span><span class="p" data-group-id="6825130356-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="0182771507-7">(</span><span class="p" data-group-id="0182771507-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0182771507-8">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0182771507-9">[</span><span class="p" data-group-id="0182771507-9">]</span><span class="p" data-group-id="0182771507-8">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="6825130356-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="6825130356-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6825130356-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_one</span><span class="p">,</span><span class="w"> </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="6825130356-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6825130356-12">[</span><span class="p" data-group-id="6825130356-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6825130356-14">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6825130356-15">[</span><span class="p" data-group-id="6825130356-15">]</span><span class="p" data-group-id="6825130356-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="0182771507-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="0182771507-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0182771507-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_one</span><span class="p">,</span><span class="w"> </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="0182771507-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0182771507-12">[</span><span class="p" data-group-id="0182771507-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0182771507-14">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0182771507-15">[</span><span class="p" data-group-id="0182771507-15">]</span><span class="p" data-group-id="0182771507-14">}</span><span class="p">,</span><span class="w">
│ │ │ │                      </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">permanent</span><span class="p">,</span><span class="w">
│ │ │ │                      </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w">
│ │ │ │                      </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6825130356-16">[</span><span class="ss">ch3</span><span class="p" data-group-id="6825130356-16">]</span><span class="p" data-group-id="6825130356-13">}</span><span class="p" data-group-id="6825130356-12">]</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6825130356-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6825130356-18">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="6825130356-18">}</span><span class="p" data-group-id="6825130356-17">}</span><span class="p">.</span></code></pre><p>The <code class="inline">SupFlags</code> variable in the return value from <code class="inline">init/1</code> represents the
│ │ │ │ +                    </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0182771507-16">[</span><span class="ss">ch3</span><span class="p" data-group-id="0182771507-16">]</span><span class="p" data-group-id="0182771507-13">}</span><span class="p" data-group-id="0182771507-12">]</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0182771507-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0182771507-18">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="0182771507-18">}</span><span class="p" data-group-id="0182771507-17">}</span><span class="p">.</span></code></pre><p>The <code class="inline">SupFlags</code> variable in the return value from <code class="inline">init/1</code> represents the
│ │ │ │  <a href="sup_princ.xhtml#flags">supervisor flags</a>.</p><p>The <code class="inline">ChildSpecs</code> variable in the return value from <code class="inline">init/1</code> is a list of
│ │ │ │  <a href="sup_princ.xhtml#spec">child specifications</a>.</p><p><a href="" id="flags"></a></p><h2 id="supervisor-flags" class="section-heading">
│ │ │ │    <a href="#supervisor-flags" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Supervisor Flags</span>
│ │ │ │  </h2>
│ │ │ │ -<p>This is the type definition for the supervisor flags:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sup_flags</span><span class="p" data-group-id="0497549705-1">(</span><span class="p" data-group-id="0497549705-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0497549705-2">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">strategy</span><span class="p" data-group-id="0497549705-3">(</span><span class="p" data-group-id="0497549705-3">)</span><span class="p">,</span><span class="w">           </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -                </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="0497549705-4">(</span><span class="p" data-group-id="0497549705-4">)</span><span class="p">,</span><span class="w">   </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -                </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="0497549705-5">(</span><span class="p" data-group-id="0497549705-5">)</span><span class="p">,</span><span class="w">          </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -                </span><span class="ss">auto_shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="0497549705-6">(</span><span class="p" data-group-id="0497549705-6">)</span><span class="p" data-group-id="0497549705-2">}</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -    </span><span class="nf">strategy</span><span class="p" data-group-id="0497549705-7">(</span><span class="p" data-group-id="0497549705-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">one_for_all</span><span class="w">
│ │ │ │ +<p>This is the type definition for the supervisor flags:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sup_flags</span><span class="p" data-group-id="6335340599-1">(</span><span class="p" data-group-id="6335340599-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6335340599-2">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">strategy</span><span class="p" data-group-id="6335340599-3">(</span><span class="p" data-group-id="6335340599-3">)</span><span class="p">,</span><span class="w">           </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +                </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6335340599-4">(</span><span class="p" data-group-id="6335340599-4">)</span><span class="p">,</span><span class="w">   </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +                </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="6335340599-5">(</span><span class="p" data-group-id="6335340599-5">)</span><span class="p">,</span><span class="w">          </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +                </span><span class="ss">auto_shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="6335340599-6">(</span><span class="p" data-group-id="6335340599-6">)</span><span class="p" data-group-id="6335340599-2">}</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +    </span><span class="nf">strategy</span><span class="p" data-group-id="6335340599-7">(</span><span class="p" data-group-id="6335340599-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">one_for_all</span><span class="w">
│ │ │ │                 </span><span class="p">|</span><span class="w"> </span><span class="ss">one_for_one</span><span class="w">
│ │ │ │                 </span><span class="p">|</span><span class="w"> </span><span class="ss">rest_for_one</span><span class="w">
│ │ │ │                 </span><span class="p">|</span><span class="w"> </span><span class="ss">simple_one_for_one</span><span class="w">
│ │ │ │ -    </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="0497549705-8">(</span><span class="p" data-group-id="0497549705-8">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">never</span><span class="w">
│ │ │ │ +    </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="6335340599-8">(</span><span class="p" data-group-id="6335340599-8">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">never</span><span class="w">
│ │ │ │                      </span><span class="p">|</span><span class="w"> </span><span class="ss">any_significant</span><span class="w">
│ │ │ │                      </span><span class="p">|</span><span class="w"> </span><span class="ss">all_significant</span></code></pre><ul><li><code class="inline">strategy</code> specifies the <a href="sup_princ.xhtml#strategy">restart strategy</a>.</li><li><code class="inline">intensity</code> and <code class="inline">period</code> specify the
│ │ │ │  <a href="sup_princ.xhtml#max_intensity">maximum restart intensity</a>.</li><li><code class="inline">auto_shutdown</code> specifies whether and when a supervisor should
│ │ │ │  <a href="sup_princ.xhtml#automatic-shutdown">automatically shut itself down</a>.</li></ul><p><a href="" id="strategy"></a></p><h2 id="restart-strategy" class="section-heading">
│ │ │ │    <a href="#restart-strategy" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │ @@ -313,28 +313,28 @@
│ │ │ │  exhaust the <a href="sup_princ.xhtml#max_intensity">Maximum Restart Intensity</a> of the
│ │ │ │  parent supervisor.</p></section><p><a href="" id="spec"></a></p><h2 id="child-specification" class="section-heading">
│ │ │ │    <a href="#child-specification" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Child Specification</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The type definition for a child specification is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">child_spec</span><span class="p" data-group-id="8380048988-1">(</span><span class="p" data-group-id="8380048988-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8380048988-2">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">child_id</span><span class="p" data-group-id="8380048988-3">(</span><span class="p" data-group-id="8380048988-3">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% mandatory</span><span class="w">
│ │ │ │ -                 </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">mfargs</span><span class="p" data-group-id="8380048988-4">(</span><span class="p" data-group-id="8380048988-4">)</span><span class="p">,</span><span class="w">            </span><span class="c1">% mandatory</span><span class="w">
│ │ │ │ -                 </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">restart</span><span class="p" data-group-id="8380048988-5">(</span><span class="p" data-group-id="8380048988-5">)</span><span class="p">,</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -                 </span><span class="ss">significant</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">significant</span><span class="p" data-group-id="8380048988-6">(</span><span class="p" data-group-id="8380048988-6">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -                 </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">shutdown</span><span class="p" data-group-id="8380048988-7">(</span><span class="p" data-group-id="8380048988-7">)</span><span class="p">,</span><span class="w">       </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -                 </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">worker</span><span class="p" data-group-id="8380048988-8">(</span><span class="p" data-group-id="8380048988-8">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -                 </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">modules</span><span class="p" data-group-id="8380048988-9">(</span><span class="p" data-group-id="8380048988-9">)</span><span class="p" data-group-id="8380048988-2">}</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ │ -    </span><span class="nf">child_id</span><span class="p" data-group-id="8380048988-10">(</span><span class="p" data-group-id="8380048988-10">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="8380048988-11">(</span><span class="p" data-group-id="8380048988-11">)</span><span class="w">
│ │ │ │ -    </span><span class="nf">mfargs</span><span class="p" data-group-id="8380048988-12">(</span><span class="p" data-group-id="8380048988-12">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8380048988-13">{</span><span class="n">M</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">module</span><span class="p" data-group-id="8380048988-14">(</span><span class="p" data-group-id="8380048988-14">)</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="8380048988-15">(</span><span class="p" data-group-id="8380048988-15">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="8380048988-16">[</span><span class="nf">term</span><span class="p" data-group-id="8380048988-17">(</span><span class="p" data-group-id="8380048988-17">)</span><span class="p" data-group-id="8380048988-16">]</span><span class="p" data-group-id="8380048988-13">}</span><span class="w">
│ │ │ │ -    </span><span class="nf">modules</span><span class="p" data-group-id="8380048988-18">(</span><span class="p" data-group-id="8380048988-18">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8380048988-19">[</span><span class="nf">module</span><span class="p" data-group-id="8380048988-20">(</span><span class="p" data-group-id="8380048988-20">)</span><span class="p" data-group-id="8380048988-19">]</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">dynamic</span><span class="w">
│ │ │ │ -    </span><span class="nf">restart</span><span class="p" data-group-id="8380048988-21">(</span><span class="p" data-group-id="8380048988-21">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">permanent</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">transient</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">temporary</span><span class="w">
│ │ │ │ -    </span><span class="nf">significant</span><span class="p" data-group-id="8380048988-22">(</span><span class="p" data-group-id="8380048988-22">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="8380048988-23">(</span><span class="p" data-group-id="8380048988-23">)</span><span class="w">
│ │ │ │ -    </span><span class="nf">shutdown</span><span class="p" data-group-id="8380048988-24">(</span><span class="p" data-group-id="8380048988-24">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">timeout</span><span class="p" data-group-id="8380048988-25">(</span><span class="p" data-group-id="8380048988-25">)</span><span class="w">
│ │ │ │ -    </span><span class="nf">worker</span><span class="p" data-group-id="8380048988-26">(</span><span class="p" data-group-id="8380048988-26">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">worker</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">supervisor</span></code></pre><ul><li><p><code class="inline">id</code> is used to identify the child specification internally by the supervisor.</p><p>The <code class="inline">id</code> key is mandatory.</p><p>Note that this identifier occasionally has been called &quot;name&quot;. As far as
│ │ │ │ +<p>The type definition for a child specification is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">child_spec</span><span class="p" data-group-id="0058342771-1">(</span><span class="p" data-group-id="0058342771-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0058342771-2">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">child_id</span><span class="p" data-group-id="0058342771-3">(</span><span class="p" data-group-id="0058342771-3">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% mandatory</span><span class="w">
│ │ │ │ +                 </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">mfargs</span><span class="p" data-group-id="0058342771-4">(</span><span class="p" data-group-id="0058342771-4">)</span><span class="p">,</span><span class="w">            </span><span class="c1">% mandatory</span><span class="w">
│ │ │ │ +                 </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">restart</span><span class="p" data-group-id="0058342771-5">(</span><span class="p" data-group-id="0058342771-5">)</span><span class="p">,</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +                 </span><span class="ss">significant</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">significant</span><span class="p" data-group-id="0058342771-6">(</span><span class="p" data-group-id="0058342771-6">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +                 </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">shutdown</span><span class="p" data-group-id="0058342771-7">(</span><span class="p" data-group-id="0058342771-7">)</span><span class="p">,</span><span class="w">       </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +                 </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">worker</span><span class="p" data-group-id="0058342771-8">(</span><span class="p" data-group-id="0058342771-8">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +                 </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">modules</span><span class="p" data-group-id="0058342771-9">(</span><span class="p" data-group-id="0058342771-9">)</span><span class="p" data-group-id="0058342771-2">}</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ │ +    </span><span class="nf">child_id</span><span class="p" data-group-id="0058342771-10">(</span><span class="p" data-group-id="0058342771-10">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0058342771-11">(</span><span class="p" data-group-id="0058342771-11">)</span><span class="w">
│ │ │ │ +    </span><span class="nf">mfargs</span><span class="p" data-group-id="0058342771-12">(</span><span class="p" data-group-id="0058342771-12">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0058342771-13">{</span><span class="n">M</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">module</span><span class="p" data-group-id="0058342771-14">(</span><span class="p" data-group-id="0058342771-14">)</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="0058342771-15">(</span><span class="p" data-group-id="0058342771-15">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="0058342771-16">[</span><span class="nf">term</span><span class="p" data-group-id="0058342771-17">(</span><span class="p" data-group-id="0058342771-17">)</span><span class="p" data-group-id="0058342771-16">]</span><span class="p" data-group-id="0058342771-13">}</span><span class="w">
│ │ │ │ +    </span><span class="nf">modules</span><span class="p" data-group-id="0058342771-18">(</span><span class="p" data-group-id="0058342771-18">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0058342771-19">[</span><span class="nf">module</span><span class="p" data-group-id="0058342771-20">(</span><span class="p" data-group-id="0058342771-20">)</span><span class="p" data-group-id="0058342771-19">]</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">dynamic</span><span class="w">
│ │ │ │ +    </span><span class="nf">restart</span><span class="p" data-group-id="0058342771-21">(</span><span class="p" data-group-id="0058342771-21">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">permanent</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">transient</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">temporary</span><span class="w">
│ │ │ │ +    </span><span class="nf">significant</span><span class="p" data-group-id="0058342771-22">(</span><span class="p" data-group-id="0058342771-22">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="0058342771-23">(</span><span class="p" data-group-id="0058342771-23">)</span><span class="w">
│ │ │ │ +    </span><span class="nf">shutdown</span><span class="p" data-group-id="0058342771-24">(</span><span class="p" data-group-id="0058342771-24">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">timeout</span><span class="p" data-group-id="0058342771-25">(</span><span class="p" data-group-id="0058342771-25">)</span><span class="w">
│ │ │ │ +    </span><span class="nf">worker</span><span class="p" data-group-id="0058342771-26">(</span><span class="p" data-group-id="0058342771-26">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">worker</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">supervisor</span></code></pre><ul><li><p><code class="inline">id</code> is used to identify the child specification internally by the supervisor.</p><p>The <code class="inline">id</code> key is mandatory.</p><p>Note that this identifier occasionally has been called &quot;name&quot;. As far as
│ │ │ │  possible, the terms &quot;identifier&quot; or &quot;id&quot; are now used but in order to keep
│ │ │ │  backwards compatibility, some occurrences of &quot;name&quot; can still be found, for
│ │ │ │  example in error messages.</p></li><li><p><code class="inline">start</code> defines the function call used to start the child process. It is a
│ │ │ │  module-function-arguments tuple used as <a href="../../../lib/../erts/doc/html/erlang.html#apply/3"><code class="inline">apply(M, F, A)</code></a>.</p><p>It is to be (or result in) a call to any of the following:</p><ul><li><a href="../../../lib/stdlib/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link/2,3</code></a></li><li><a href="../../../lib/stdlib/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/3,4</code></a></li><li><a href="../../../lib/stdlib/doc/html/gen_statem.html#start_link/4"><code class="inline">gen_statem:start_link/3,4</code></a></li><li><a href="../../../lib/stdlib/doc/html/gen_event.html#start_link/2"><code class="inline">gen_event:start_link/0,1,2</code></a></li><li>A function compliant with these functions. For details, see
│ │ │ │  <a href="../../../lib/stdlib/doc/html/supervisor.html"><code class="inline">supervisor</code></a>.</li></ul><p>The <code class="inline">start</code> key is mandatory.</p></li><li><p><a href="" id="restart"></a> <code class="inline">restart</code> defines when a terminated child process is to be
│ │ │ │  restarted.</p><ul><li>A <code class="inline">permanent</code> child process is always restarted.</li><li>A <code class="inline">temporary</code> child process is never restarted (not even when the supervisor
│ │ │ │  restart strategy is <code class="inline">rest_for_one</code> or <code class="inline">one_for_all</code> and a sibling death
│ │ │ │ @@ -362,53 +362,53 @@
│ │ │ │  <code class="inline">supervisor</code>, the default value <code class="inline">infinity</code> will be used.</p></li><li><p><code class="inline">type</code> specifies whether the child process is a supervisor or a worker.</p><p>The <code class="inline">type</code> key is optional. If it is not given, the default value <code class="inline">worker</code>
│ │ │ │  will be used.</p></li><li><p><code class="inline">modules</code> has to be a list consisting of a single element. The value
│ │ │ │  of that element depends on the behaviour of the process:</p><ul><li>If the child process is a <code class="inline">gen_event</code>, the element has to be the atom
│ │ │ │  <code class="inline">dynamic</code>.</li><li>Otherwise, the element should be <code class="inline">Module</code>, where <code class="inline">Module</code> is the
│ │ │ │  name of the callback module.</li></ul><p>This information is used by the release handler during upgrades and
│ │ │ │  downgrades; see <a href="release_handling.xhtml">Release Handling</a>.</p><p>The <code class="inline">modules</code> key is optional. If it is not given, it defaults to <code class="inline">[M]</code>, where
│ │ │ │  <code class="inline">M</code> comes from the child's start <code class="inline">{M,F,A}</code>.</p></li></ul><p><em>Example:</em> The child specification to start the server <code class="inline">ch3</code> in the previous
│ │ │ │ -example look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2875751896-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2875751896-2">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2875751896-3">[</span><span class="p" data-group-id="2875751896-3">]</span><span class="p" data-group-id="2875751896-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +example look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7645354853-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7645354853-2">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7645354853-3">[</span><span class="p" data-group-id="7645354853-3">]</span><span class="p" data-group-id="7645354853-2">}</span><span class="p">,</span><span class="w">
│ │ │ │    </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">permanent</span><span class="p">,</span><span class="w">
│ │ │ │    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w">
│ │ │ │    </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2875751896-4">[</span><span class="ss">ch3</span><span class="p" data-group-id="2875751896-4">]</span><span class="p" data-group-id="2875751896-1">}</span></code></pre><p>or simplified, relying on the default values:</p><pre><code class="text">#{id =&gt; ch3,
│ │ │ │ +  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7645354853-4">[</span><span class="ss">ch3</span><span class="p" data-group-id="7645354853-4">]</span><span class="p" data-group-id="7645354853-1">}</span></code></pre><p>or simplified, relying on the default values:</p><pre><code class="text">#{id =&gt; ch3,
│ │ │ │    start =&gt; {ch3, start_link, []},
│ │ │ │    shutdown =&gt; brutal_kill}</code></pre><p>Example: A child specification to start the event manager from the chapter about
│ │ │ │ -<a href="events.xhtml#mgr">gen_event</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6287898595-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">error_man</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6287898595-2">{</span><span class="ss">gen_event</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6287898595-3">[</span><span class="p" data-group-id="6287898595-4">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="6287898595-4">}</span><span class="p" data-group-id="6287898595-3">]</span><span class="p" data-group-id="6287898595-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">dynamic</span><span class="p" data-group-id="6287898595-1">}</span></code></pre><p>Both server and event manager are registered processes which can be expected to
│ │ │ │ +<a href="events.xhtml#mgr">gen_event</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8301549900-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">error_man</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8301549900-2">{</span><span class="ss">gen_event</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8301549900-3">[</span><span class="p" data-group-id="8301549900-4">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="8301549900-4">}</span><span class="p" data-group-id="8301549900-3">]</span><span class="p" data-group-id="8301549900-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">dynamic</span><span class="p" data-group-id="8301549900-1">}</span></code></pre><p>Both server and event manager are registered processes which can be expected to
│ │ │ │  be always accessible. Thus they are specified to be <code class="inline">permanent</code>.</p><p><code class="inline">ch3</code> does not need to do any cleaning up before termination. Thus, no shutdown
│ │ │ │  time is needed, but <code class="inline">brutal_kill</code> is sufficient. <code class="inline">error_man</code> can need some time
│ │ │ │  for the event handlers to clean up, thus the shutdown time is set to 5000 ms
│ │ │ │ -(which is the default value).</p><p>Example: A child specification to start another supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6001181832-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">sup</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6001181832-2">{</span><span class="ss">sup</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6001181832-3">[</span><span class="p" data-group-id="6001181832-3">]</span><span class="p" data-group-id="6001181832-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +(which is the default value).</p><p>Example: A child specification to start another supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1663475921-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">sup</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1663475921-2">{</span><span class="ss">sup</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1663475921-3">[</span><span class="p" data-group-id="1663475921-3">]</span><span class="p" data-group-id="1663475921-2">}</span><span class="p">,</span><span class="w">
│ │ │ │    </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">transient</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="6001181832-1">}</span><span class="w"> </span><span class="c1">% will cause default shutdown=&gt;infinity</span></code></pre><p><a href="" id="super_tree"></a></p><h2 id="starting-a-supervisor" class="section-heading">
│ │ │ │ +  </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1663475921-1">}</span><span class="w"> </span><span class="c1">% will cause default shutdown=&gt;infinity</span></code></pre><p><a href="" id="super_tree"></a></p><h2 id="starting-a-supervisor" class="section-heading">
│ │ │ │    <a href="#starting-a-supervisor" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting a Supervisor</span>
│ │ │ │  </h2>
│ │ │ │  <p>In the previous example, the supervisor is started by calling
│ │ │ │ -<code class="inline">ch_sup:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="8492369377-1">(</span><span class="p" data-group-id="8492369377-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8492369377-2">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8492369377-3">[</span><span class="p" data-group-id="8492369377-3">]</span><span class="p" data-group-id="8492369377-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch_sup:start_link</code> calls function <a href="../../../lib/stdlib/doc/html/supervisor.html#start_link/2"><code class="inline">supervisor:start_link/2</code></a>, which spawns and
│ │ │ │ +<code class="inline">ch_sup:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="9295642974-1">(</span><span class="p" data-group-id="9295642974-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9295642974-2">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9295642974-3">[</span><span class="p" data-group-id="9295642974-3">]</span><span class="p" data-group-id="9295642974-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch_sup:start_link</code> calls function <a href="../../../lib/stdlib/doc/html/supervisor.html#start_link/2"><code class="inline">supervisor:start_link/2</code></a>, which spawns and
│ │ │ │  links to a new process, a supervisor.</p><ul><li>The first argument, <code class="inline">ch_sup</code>, is the name of the callback module, that is, the
│ │ │ │  module where the <code class="inline">init</code> callback function is located.</li><li>The second argument, <code class="inline">[]</code>, is a term that is passed as is to the callback
│ │ │ │  function <code class="inline">init</code>. Here, <code class="inline">init</code> does not need any data and ignores the argument.</li></ul><p>In this case, the supervisor is not registered. Instead its pid must be used. A
│ │ │ │  name can be specified by calling
│ │ │ │  <a href="../../../lib/stdlib/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link({local, Name}, Module, Args)</code></a>
│ │ │ │  or
│ │ │ │  <a href="../../../lib/stdlib/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link({global, Name}, Module, Args)</code></a>.</p><p>The new supervisor process calls the callback function <code class="inline">ch_sup:init([])</code>. <code class="inline">init</code>
│ │ │ │ -has to return <code class="inline">{ok, {SupFlags, ChildSpecs}}</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="5726620690-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="5726620690-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5726620690-2">#{</span><span class="p" data-group-id="5726620690-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5726620690-3">[</span><span class="p" data-group-id="5726620690-4">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5726620690-5">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5726620690-6">[</span><span class="p" data-group-id="5726620690-6">]</span><span class="p" data-group-id="5726620690-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="5726620690-4">}</span><span class="p" data-group-id="5726620690-3">]</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5726620690-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5726620690-8">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="5726620690-8">}</span><span class="p" data-group-id="5726620690-7">}</span><span class="p">.</span></code></pre><p>Subsequently, the supervisor starts its child processes according to the child
│ │ │ │ +has to return <code class="inline">{ok, {SupFlags, ChildSpecs}}</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="4626214118-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="4626214118-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4626214118-2">#{</span><span class="p" data-group-id="4626214118-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4626214118-3">[</span><span class="p" data-group-id="4626214118-4">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4626214118-5">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4626214118-6">[</span><span class="p" data-group-id="4626214118-6">]</span><span class="p" data-group-id="4626214118-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="4626214118-4">}</span><span class="p" data-group-id="4626214118-3">]</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4626214118-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4626214118-8">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="4626214118-8">}</span><span class="p" data-group-id="4626214118-7">}</span><span class="p">.</span></code></pre><p>Subsequently, the supervisor starts its child processes according to the child
│ │ │ │  specifications in the start specification. In this case there is a single child
│ │ │ │  process, called <code class="inline">ch3</code>.</p><p><a href="../../../lib/stdlib/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link/3</code></a> is synchronous. It does not return until all child
│ │ │ │  processes have been started.</p><h2 id="adding-a-child-process" class="section-heading">
│ │ │ │    <a href="#adding-a-child-process" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Adding a Child Process</span>
│ │ │ │ @@ -437,31 +437,31 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Simplified one_for_one Supervisors</span>
│ │ │ │  </h2>
│ │ │ │  <p>A supervisor with restart strategy <code class="inline">simple_one_for_one</code> is a simplified
│ │ │ │  <code class="inline">one_for_one</code> supervisor, where all child processes are dynamically added
│ │ │ │  instances of the same process.</p><p>The following is an example of a callback module for a <code class="inline">simple_one_for_one</code>
│ │ │ │ -supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3038274531-1">(</span><span class="ss">simple_sup</span><span class="p" data-group-id="3038274531-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="3038274531-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="3038274531-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8725343664-1">(</span><span class="ss">simple_sup</span><span class="p" data-group-id="8725343664-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="8725343664-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="8725343664-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3038274531-3">(</span><span class="p" data-group-id="3038274531-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3038274531-4">]</span><span class="p" data-group-id="3038274531-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3038274531-5">(</span><span class="p" data-group-id="3038274531-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3038274531-6">]</span><span class="p" data-group-id="3038274531-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8725343664-3">(</span><span class="p" data-group-id="8725343664-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8725343664-4">]</span><span class="p" data-group-id="8725343664-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8725343664-5">(</span><span class="p" data-group-id="8725343664-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8725343664-6">]</span><span class="p" data-group-id="8725343664-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="3038274531-7">(</span><span class="p" data-group-id="3038274531-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3038274531-8">(</span><span class="ss">simple_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3038274531-9">[</span><span class="p" data-group-id="3038274531-9">]</span><span class="p" data-group-id="3038274531-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="8725343664-7">(</span><span class="p" data-group-id="8725343664-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8725343664-8">(</span><span class="ss">simple_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8725343664-9">[</span><span class="p" data-group-id="8725343664-9">]</span><span class="p" data-group-id="8725343664-8">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3038274531-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="3038274531-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3038274531-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">simple_one_for_one</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="8725343664-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="8725343664-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8725343664-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">simple_one_for_one</span><span class="p">,</span><span class="w">
│ │ │ │                   </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ │ -                 </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3038274531-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3038274531-12">[</span><span class="p" data-group-id="3038274531-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">call</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3038274531-14">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3038274531-15">[</span><span class="p" data-group-id="3038274531-15">]</span><span class="p" data-group-id="3038274531-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="3038274531-13">}</span><span class="p" data-group-id="3038274531-12">]</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3038274531-16">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3038274531-17">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="3038274531-17">}</span><span class="p" data-group-id="3038274531-16">}</span><span class="p">.</span></code></pre><p>When started, the supervisor does not start any child
│ │ │ │ +                 </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="8725343664-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8725343664-12">[</span><span class="p" data-group-id="8725343664-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">call</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8725343664-14">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8725343664-15">[</span><span class="p" data-group-id="8725343664-15">]</span><span class="p" data-group-id="8725343664-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="8725343664-13">}</span><span class="p" data-group-id="8725343664-12">]</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8725343664-16">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8725343664-17">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="8725343664-17">}</span><span class="p" data-group-id="8725343664-16">}</span><span class="p">.</span></code></pre><p>When started, the supervisor does not start any child
│ │ │ │  processes. Instead, all child processes need to be added dynamically by
│ │ │ │  calling <a href="../../../lib/stdlib/doc/html/supervisor.html#start_child/2"><code class="inline">supervisor:start_child(Sup, List)</code></a>.</p><p><code class="inline">Sup</code> is the pid, or name, of the supervisor. <code class="inline">List</code> is an arbitrary list of
│ │ │ │  terms, which are added to the list of arguments specified in the child
│ │ │ │  specification. If the start function is specified as <code class="inline">{M, F, A}</code>, the child
│ │ │ │  process is started by calling <a href="../../../lib/../erts/doc/html/erlang.html#apply/3"><code class="inline">apply(M, F, A++List)</code></a>.</p><p>For example, adding a child to <code class="inline">simple_sup</code> above:</p><pre><code class="text">supervisor:start_child(Pid, [id1])</code></pre><p>The result is that the child process is started by calling
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#apply/3"><code class="inline">apply(call, start_link, []++[id1])</code></a>, or actually:</p><pre><code class="text">call:start_link(id1)</code></pre><p>A child under a <code class="inline">simple_one_for_one</code> supervisor can be terminated with the
│ │ │ │  following:</p><pre><code class="text">supervisor:terminate_child(Sup, Pid)</code></pre><p><code class="inline">Sup</code> is the pid, or name, of the supervisor and <code class="inline">Pid</code> is the pid of the child.</p><p>Because a <code class="inline">simple_one_for_one</code> supervisor can have many children, it shuts them
│ │ │ ├── OEBPS/statem.xhtml
│ │ │ │ @@ -29,15 +29,15 @@
│ │ │ │  </h2>
│ │ │ │  <p>Established Automata Theory does not deal much with how a <em>state transition</em>
│ │ │ │  is triggered, but assumes that the output is a function of the input
│ │ │ │  (and the state) and that they are some kind of values.</p><p>For an Event-Driven State Machine, the input is an <em>event</em> that triggers
│ │ │ │  a <em>state transition</em> and the output is actions executed during
│ │ │ │  the <em>state transition</em>.  Analogously to the mathematical model
│ │ │ │  of a Finite State Machine, it can be described as a set of relations
│ │ │ │ -of the following form:</p><pre><code class="makeup erlang" translate="no"><span class="n">State</span><span class="p" data-group-id="8204570011-1">(</span><span class="n">S</span><span class="p" data-group-id="8204570011-1">)</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="8204570011-2">(</span><span class="n">E</span><span class="p" data-group-id="8204570011-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Actions</span><span class="p" data-group-id="8204570011-3">(</span><span class="n">A</span><span class="p" data-group-id="8204570011-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="8204570011-4">(</span><span class="n">S</span><span class="err">&#39;</span><span class="p" data-group-id="8204570011-4">)</span></code></pre><p>These relations are interpreted as follows: if we are in state <code class="inline">S</code>,
│ │ │ │ +of the following form:</p><pre><code class="makeup erlang" translate="no"><span class="n">State</span><span class="p" data-group-id="7344330674-1">(</span><span class="n">S</span><span class="p" data-group-id="7344330674-1">)</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="7344330674-2">(</span><span class="n">E</span><span class="p" data-group-id="7344330674-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Actions</span><span class="p" data-group-id="7344330674-3">(</span><span class="n">A</span><span class="p" data-group-id="7344330674-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7344330674-4">(</span><span class="n">S</span><span class="err">&#39;</span><span class="p" data-group-id="7344330674-4">)</span></code></pre><p>These relations are interpreted as follows: if we are in state <code class="inline">S</code>,
│ │ │ │  and event <code class="inline">E</code> occurs, we are to perform actions <code class="inline">A</code>, and make a transition
│ │ │ │  to state <code class="inline">S'</code>.  Notice that <code class="inline">S'</code> can be equal to <code class="inline">S</code>,
│ │ │ │  and that <code class="inline">A</code> can be empty.</p><p>In <code class="inline">gen_statem</code> we define a <em>state change</em> as a <em>state transition</em> in which the
│ │ │ │  new state <code class="inline">S'</code> is different from the current state <code class="inline">S</code>, where &quot;different&quot; means
│ │ │ │  Erlang's strict inequality: <code class="inline">=/=</code> also known as &quot;does not match&quot;. <code class="inline">gen_statem</code>
│ │ │ │  does more things during <em>state changes</em> than during other <em>state transitions</em>.</p><p>As <code class="inline">A</code> and <code class="inline">S'</code> depend only on <code class="inline">S</code> and <code class="inline">E</code>, the kind of state machine described
│ │ │ │  here is a Mealy machine (see, for example, the Wikipedia article
│ │ │ │ @@ -310,20 +310,20 @@
│ │ │ │    </a>
│ │ │ │    <span class="text">State Enter Calls</span>
│ │ │ │  </h2>
│ │ │ │  <p>The <code class="inline">gen_statem</code> behaviour can, if this is enabled, regardless of <em>callback
│ │ │ │  mode</em>, automatically call the <a href="../../../lib/stdlib/doc/html/gen_statem.html#t:state_enter/0"><em>state callback</em></a>
│ │ │ │  with special arguments whenever the state changes, so you can write
│ │ │ │  state enter actions near the rest of the <em>state transition</em> rules.
│ │ │ │ -It typically looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">StateName</span><span class="p" data-group-id="6885621562-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6885621562-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +It typically looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">StateName</span><span class="p" data-group-id="4049140865-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4049140865-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">enter</span><span class="w"> </span><span class="ss">actions</span><span class="w"> </span><span class="ss">here</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6885621562-2">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="6885621562-2">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="n">StateName</span><span class="p" data-group-id="6885621562-3">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6885621562-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4049140865-2">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="4049140865-2">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="n">StateName</span><span class="p" data-group-id="4049140865-3">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4049140865-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">actions</span><span class="w"> </span><span class="ss">here</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6885621562-4">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewStateName</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="6885621562-4">}</span><span class="p">.</span></code></pre><p>Since the <em>state enter call</em> is not an event there are restrictions on the
│ │ │ │ +    </span><span class="p" data-group-id="4049140865-4">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewStateName</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="4049140865-4">}</span><span class="p">.</span></code></pre><p>Since the <em>state enter call</em> is not an event there are restrictions on the
│ │ │ │  allowed return value and state <a href="#transition-actions"><em>transition actions</em></a>.
│ │ │ │  You must not change the state, <a href="#postponing-events">postpone</a> this non-event,
│ │ │ │  <a href="#inserted-events">insert any events</a>, or change the
│ │ │ │  <a href="#callback-module"><em>callback module</em></a>.</p><p>The first state that is entered after <a href="../../../lib/stdlib/doc/html/gen_statem.html#c:init/1"><code class="inline">gen_statem:init/1</code></a> will get
│ │ │ │  a <em>state enter call</em> with <code class="inline">OldState</code> equal to the current state.</p><p>You may repeat the <em>state enter call</em> using the <code class="inline">{repeat_state,...}</code> return
│ │ │ │  value from the <a href="#state-callback"><em>state callback</em></a>. In this case
│ │ │ │  <code class="inline">OldState</code> will also be equal to the current state.</p><p>Depending on how your state machine is specified, this can be a very useful
│ │ │ │ @@ -404,72 +404,72 @@
│ │ │ │  
│ │ │ │      locked      --&gt; check_code : {button, Button}\n* Collect Buttons
│ │ │ │      check_code  --&gt; locked     : Incorrect code
│ │ │ │      check_code  --&gt; open       : Correct code\n* do_unlock()\n* Clear Buttons\n* Set state_timeout 10 s
│ │ │ │  
│ │ │ │      open        --&gt; open   : {button, Digit}
│ │ │ │      open        --&gt; locked : state_timeout\n* do_lock()</code></pre><p>This code lock state machine can be implemented using <a href="../../../lib/stdlib/doc/html/gen_statem.html"><code class="inline">gen_statem</code></a> with
│ │ │ │ -the following <em>callback module</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3049696751-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="3049696751-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="3049696751-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="3049696751-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3049696751-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock</span><span class="p" data-group-id="3049696751-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +the following <em>callback module</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3753317433-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="3753317433-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="3753317433-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="3753317433-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3753317433-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock</span><span class="p" data-group-id="3753317433-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3049696751-4">(</span><span class="p" data-group-id="3049696751-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3049696751-5">]</span><span class="p" data-group-id="3049696751-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3049696751-6">(</span><span class="p" data-group-id="3049696751-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3049696751-7">]</span><span class="p" data-group-id="3049696751-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3049696751-8">(</span><span class="p" data-group-id="3049696751-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="3049696751-9">]</span><span class="p" data-group-id="3049696751-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3049696751-10">(</span><span class="p" data-group-id="3049696751-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="3049696751-11">]</span><span class="p" data-group-id="3049696751-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="3049696751-12">(</span><span class="n">Code</span><span class="p" data-group-id="3049696751-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3049696751-13">(</span><span class="p" data-group-id="3049696751-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="3049696751-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3049696751-15">[</span><span class="p" data-group-id="3049696751-15">]</span><span class="p" data-group-id="3049696751-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">button</span><span class="p" data-group-id="3049696751-16">(</span><span class="n">Button</span><span class="p" data-group-id="3049696751-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="3049696751-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3049696751-18">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="3049696751-18">}</span><span class="p" data-group-id="3049696751-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3049696751-19">(</span><span class="n">Code</span><span class="p" data-group-id="3049696751-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="3049696751-20">(</span><span class="p" data-group-id="3049696751-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3049696751-21">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="3049696751-22">(</span><span class="n">Code</span><span class="p" data-group-id="3049696751-22">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3049696751-23">[</span><span class="p" data-group-id="3049696751-23">]</span><span class="p" data-group-id="3049696751-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3049696751-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3049696751-24">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="3049696751-25">(</span><span class="p" data-group-id="3049696751-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">state_functions</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="4445603305-1">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4445603305-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4445603305-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4445603305-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="4445603305-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4445603305-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3753317433-4">(</span><span class="p" data-group-id="3753317433-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3753317433-5">]</span><span class="p" data-group-id="3753317433-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3753317433-6">(</span><span class="p" data-group-id="3753317433-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3753317433-7">]</span><span class="p" data-group-id="3753317433-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3753317433-8">(</span><span class="p" data-group-id="3753317433-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="3753317433-9">]</span><span class="p" data-group-id="3753317433-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3753317433-10">(</span><span class="p" data-group-id="3753317433-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="3753317433-11">]</span><span class="p" data-group-id="3753317433-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="3753317433-12">(</span><span class="n">Code</span><span class="p" data-group-id="3753317433-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3753317433-13">(</span><span class="p" data-group-id="3753317433-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="3753317433-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3753317433-15">[</span><span class="p" data-group-id="3753317433-15">]</span><span class="p" data-group-id="3753317433-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">button</span><span class="p" data-group-id="3753317433-16">(</span><span class="n">Button</span><span class="p" data-group-id="3753317433-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="3753317433-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3753317433-18">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="3753317433-18">}</span><span class="p" data-group-id="3753317433-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="3753317433-19">(</span><span class="n">Code</span><span class="p" data-group-id="3753317433-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="3753317433-20">(</span><span class="p" data-group-id="3753317433-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3753317433-21">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="3753317433-22">(</span><span class="n">Code</span><span class="p" data-group-id="3753317433-22">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3753317433-23">[</span><span class="p" data-group-id="3753317433-23">]</span><span class="p" data-group-id="3753317433-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3753317433-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3753317433-24">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="3753317433-25">(</span><span class="p" data-group-id="3753317433-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">state_functions</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="3132939274-1">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3132939274-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="3132939274-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="3132939274-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="3132939274-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3132939274-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │          </span><span class="k">if</span><span class="w">
│ │ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="4445603305-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="4445603305-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="3132939274-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="3132939274-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="4445603305-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="4445603305-5">)</span><span class="w">
│ │ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="4445603305-6">[</span><span class="n">Button</span><span class="p" data-group-id="4445603305-6">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="3132939274-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="3132939274-5">)</span><span class="w">
│ │ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="3132939274-6">[</span><span class="n">Button</span><span class="p" data-group-id="3132939274-6">]</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="4445603305-7">(</span><span class="p" data-group-id="4445603305-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="4445603305-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4445603305-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="4445603305-10">[</span><span class="p" data-group-id="4445603305-10">]</span><span class="p" data-group-id="4445603305-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="4445603305-11">[</span><span class="p" data-group-id="4445603305-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="4445603305-12">}</span><span class="p" data-group-id="4445603305-11">]</span><span class="p" data-group-id="4445603305-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="3132939274-7">(</span><span class="p" data-group-id="3132939274-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="3132939274-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3132939274-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="3132939274-10">[</span><span class="p" data-group-id="3132939274-10">]</span><span class="p" data-group-id="3132939274-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="3132939274-11">[</span><span class="p" data-group-id="3132939274-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="3132939274-12">}</span><span class="p" data-group-id="3132939274-11">]</span><span class="p" data-group-id="3132939274-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="4445603305-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4445603305-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="4445603305-14">}</span><span class="p" data-group-id="4445603305-13">}</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="4424330427-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="4424330427-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="4424330427-2">(</span><span class="p" data-group-id="4424330427-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4424330427-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4424330427-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="4424330427-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4424330427-5">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4424330427-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4424330427-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4424330427-6">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4424330427-6">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="2418398540-1">(</span><span class="p" data-group-id="2418398540-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2418398540-2">(</span><span class="s">&quot;Lock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2418398540-3">[</span><span class="p" data-group-id="2418398540-3">]</span><span class="p" data-group-id="2418398540-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="2418398540-4">(</span><span class="p" data-group-id="2418398540-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2418398540-5">(</span><span class="s">&quot;Unlock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2418398540-6">[</span><span class="p" data-group-id="2418398540-6">]</span><span class="p" data-group-id="2418398540-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="3132939274-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3132939274-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="3132939274-14">}</span><span class="p" data-group-id="3132939274-13">}</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="7901148656-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="7901148656-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="7901148656-2">(</span><span class="p" data-group-id="7901148656-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7901148656-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7901148656-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="7901148656-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7901148656-5">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7901148656-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7901148656-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7901148656-6">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7901148656-6">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="1047448826-1">(</span><span class="p" data-group-id="1047448826-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1047448826-2">(</span><span class="s">&quot;Lock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1047448826-3">[</span><span class="p" data-group-id="1047448826-3">]</span><span class="p" data-group-id="1047448826-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="1047448826-4">(</span><span class="p" data-group-id="1047448826-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1047448826-5">(</span><span class="s">&quot;Unlock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1047448826-6">[</span><span class="p" data-group-id="1047448826-6">]</span><span class="p" data-group-id="1047448826-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="2418398540-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="2418398540-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="2418398540-8">(</span><span class="p" data-group-id="2418398540-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="1047448826-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="1047448826-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="1047448826-8">(</span><span class="p" data-group-id="1047448826-8">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><h2 id="starting-gen_statem" class="section-heading">
│ │ │ │    <a href="#starting-gen_statem" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting gen_statem</span>
│ │ │ │  </h2>
│ │ │ │  <p>In the example in the previous section, <code class="inline">gen_statem</code> is started by calling
│ │ │ │ -<code class="inline">code_lock:start_link(Code)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="9494640162-1">(</span><span class="n">Code</span><span class="p" data-group-id="9494640162-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9494640162-2">(</span><span class="p" data-group-id="9494640162-3">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="9494640162-3">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9494640162-4">[</span><span class="p" data-group-id="9494640162-4">]</span><span class="p" data-group-id="9494640162-2">)</span><span class="p">.</span></code></pre><p><code class="inline">start_link/1</code> calls function <a href="../../../lib/stdlib/doc/html/gen_statem.html#start_link/4"><code class="inline">gen_statem:start_link/4</code></a>,
│ │ │ │ +<code class="inline">code_lock:start_link(Code)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="7495532389-1">(</span><span class="n">Code</span><span class="p" data-group-id="7495532389-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="7495532389-2">(</span><span class="p" data-group-id="7495532389-3">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="7495532389-3">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7495532389-4">[</span><span class="p" data-group-id="7495532389-4">]</span><span class="p" data-group-id="7495532389-2">)</span><span class="p">.</span></code></pre><p><code class="inline">start_link/1</code> calls function <a href="../../../lib/stdlib/doc/html/gen_statem.html#start_link/4"><code class="inline">gen_statem:start_link/4</code></a>,
│ │ │ │  which spawns and links to a new process, a <code class="inline">gen_statem</code>.</p><ul><li><p>The first argument, <code class="inline">{local,?NAME}</code>, specifies the name. In this case, the
│ │ │ │  <code class="inline">gen_statem</code> is locally registered as <code class="inline">code_lock</code> through the macro <code class="inline">?NAME</code>.</p><p>If the name is omitted, the <code class="inline">gen_statem</code> is not registered. Instead its pid
│ │ │ │  must be used. The name can also be specified as <code class="inline">{global, Name}</code>, then the
│ │ │ │  <code class="inline">gen_statem</code> is registered using <a href="../../../lib/kernel/doc/html/global.html#register_name/2"><code class="inline">global:register_name/2</code></a> in Kernel.</p></li><li><p>The second argument, <code class="inline">?MODULE</code>, is the name of the <em>callback module</em>,
│ │ │ │  that is, the module where the callback functions are located,
│ │ │ │  which is this module.</p><p>The interface functions (<code class="inline">start_link/1</code> and <code class="inline">button/1</code>) are located in the
│ │ │ │  same module as the callback functions (<code class="inline">init/1</code>, <code class="inline">locked/3</code>, and <code class="inline">open/3</code>).
│ │ │ │ @@ -479,184 +479,184 @@
│ │ │ │  see <a href="../../../lib/stdlib/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3</code></a>.</p></li></ul><p>If name registration succeeds, the new <code class="inline">gen_statem</code> process calls callback
│ │ │ │  function <code class="inline">code_lock:init(Code)</code>. This function is expected to return
│ │ │ │  <code class="inline">{ok, State, Data}</code>, where <code class="inline">State</code> is the initial state of the <code class="inline">gen_statem</code>,
│ │ │ │  in this case <code class="inline">locked</code>; assuming that the door is locked to begin with.
│ │ │ │  <code class="inline">Data</code> is the internal server data of the <code class="inline">gen_statem</code>. Here the server data
│ │ │ │  is a <a href="../../../lib/stdlib/doc/html/maps.html"><code class="inline">map()</code></a> with key <code class="inline">code</code> that stores the correct
│ │ │ │  button sequence, key <code class="inline">length</code> store its length, and key <code class="inline">buttons</code>
│ │ │ │ -that stores the collected buttons up to the same length.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="4210933877-1">(</span><span class="n">Code</span><span class="p" data-group-id="4210933877-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="4210933877-2">(</span><span class="p" data-group-id="4210933877-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4210933877-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="4210933877-4">(</span><span class="n">Code</span><span class="p" data-group-id="4210933877-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4210933877-5">[</span><span class="p" data-group-id="4210933877-5">]</span><span class="p" data-group-id="4210933877-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4210933877-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4210933877-6">}</span><span class="p">.</span></code></pre><p>Function <a href="../../../lib/stdlib/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3,4</code></a>
│ │ │ │ +that stores the collected buttons up to the same length.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="2043805929-1">(</span><span class="n">Code</span><span class="p" data-group-id="2043805929-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="2043805929-2">(</span><span class="p" data-group-id="2043805929-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2043805929-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="2043805929-4">(</span><span class="n">Code</span><span class="p" data-group-id="2043805929-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2043805929-5">[</span><span class="p" data-group-id="2043805929-5">]</span><span class="p" data-group-id="2043805929-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2043805929-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2043805929-6">}</span><span class="p">.</span></code></pre><p>Function <a href="../../../lib/stdlib/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3,4</code></a>
│ │ │ │  is synchronous. It does not return until the <code class="inline">gen_statem</code> is initialized
│ │ │ │  and is ready to receive events.</p><p>Function <a href="../../../lib/stdlib/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3,4</code></a>
│ │ │ │  must be used if the <code class="inline">gen_statem</code> is part of a supervision tree, that is,
│ │ │ │  started by a supervisor.  Function,
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#start/3"><code class="inline">gen_statem:start/3,4</code></a> can be used to start
│ │ │ │  a standalone <code class="inline">gen_statem</code>, meaning it is not part of a supervision tree.</p><p>Function <a href="../../../lib/stdlib/doc/html/gen_statem.html#c:callback_mode/0"><code class="inline">Module:callback_mode/0</code></a> selects
│ │ │ │  the <a href="#callback-modes"><code class="inline">CallbackMode</code></a> for the <em>callback module</em>,
│ │ │ │  in this case <a href="../../../lib/stdlib/doc/html/gen_statem.html#t:callback_mode/0"><code class="inline">state_functions</code></a>.
│ │ │ │ -That is, each state has its own handler function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="9712356661-1">(</span><span class="p" data-group-id="9712356661-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +That is, each state has its own handler function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="8180106766-1">(</span><span class="p" data-group-id="8180106766-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">state_functions</span><span class="p">.</span></code></pre><h2 id="handling-events" class="section-heading">
│ │ │ │    <a href="#handling-events" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Handling Events</span>
│ │ │ │  </h2>
│ │ │ │  <p>The function notifying the code lock about a button event is implemented using
│ │ │ │ -<a href="../../../lib/stdlib/doc/html/gen_statem.html#cast/2"><code class="inline">gen_statem:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">button</span><span class="p" data-group-id="5101447447-1">(</span><span class="n">Button</span><span class="p" data-group-id="5101447447-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="5101447447-2">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5101447447-3">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5101447447-3">}</span><span class="p" data-group-id="5101447447-2">)</span><span class="p">.</span></code></pre><p>The first argument is the name of the <code class="inline">gen_statem</code> and must agree with
│ │ │ │ +<a href="../../../lib/stdlib/doc/html/gen_statem.html#cast/2"><code class="inline">gen_statem:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">button</span><span class="p" data-group-id="6355542229-1">(</span><span class="n">Button</span><span class="p" data-group-id="6355542229-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="6355542229-2">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6355542229-3">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6355542229-3">}</span><span class="p" data-group-id="6355542229-2">)</span><span class="p">.</span></code></pre><p>The first argument is the name of the <code class="inline">gen_statem</code> and must agree with
│ │ │ │  the name used to start it. So, we use the same macro <code class="inline">?NAME</code> as when starting.
│ │ │ │  <code class="inline">{button, Button}</code> is the event content.</p><p>The event is sent to the <code class="inline">gen_statem</code>. When the event is received, the
│ │ │ │  <code class="inline">gen_statem</code> calls <code class="inline">StateName(cast, Event, Data)</code>, which is expected
│ │ │ │  to return a tuple <code class="inline">{next_state, NewStateName, NewData}</code>, or
│ │ │ │  <code class="inline">{next_state, NewStateName, NewData, Actions}</code>. <code class="inline">StateName</code> is the name
│ │ │ │  of the current state and <code class="inline">NewStateName</code> is the name of the next state.
│ │ │ │  <code class="inline">NewData</code> is a new value for the server data of the <code class="inline">gen_statem</code>,
│ │ │ │ -and <code class="inline">Actions</code> is a list of actions to be performed by the <code class="inline">gen_statem</code> engine.</p><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="6310710247-1">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6310710247-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6310710247-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="6310710247-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="6310710247-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6310710247-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +and <code class="inline">Actions</code> is a list of actions to be performed by the <code class="inline">gen_statem</code> engine.</p><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="6771904675-1">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6771904675-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6771904675-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6771904675-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="6771904675-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6771904675-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │          </span><span class="k">if</span><span class="w">
│ │ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="6310710247-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="6310710247-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="6771904675-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="6771904675-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="6310710247-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="6310710247-5">)</span><span class="w">
│ │ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6310710247-6">[</span><span class="n">Button</span><span class="p" data-group-id="6310710247-6">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="6771904675-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="6771904675-5">)</span><span class="w">
│ │ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6771904675-6">[</span><span class="n">Button</span><span class="p" data-group-id="6771904675-6">]</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="6310710247-7">(</span><span class="p" data-group-id="6310710247-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6310710247-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6310710247-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6310710247-10">[</span><span class="p" data-group-id="6310710247-10">]</span><span class="p" data-group-id="6310710247-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="6310710247-11">[</span><span class="p" data-group-id="6310710247-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="6310710247-12">}</span><span class="p" data-group-id="6310710247-11">]</span><span class="p" data-group-id="6310710247-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="6771904675-7">(</span><span class="p" data-group-id="6771904675-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="6771904675-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6771904675-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6771904675-10">[</span><span class="p" data-group-id="6771904675-10">]</span><span class="p" data-group-id="6771904675-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="6771904675-11">[</span><span class="p" data-group-id="6771904675-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="6771904675-12">}</span><span class="p" data-group-id="6771904675-11">]</span><span class="p" data-group-id="6771904675-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6310710247-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6310710247-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="6310710247-14">}</span><span class="p" data-group-id="6310710247-13">}</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="6771904675-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6771904675-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="6771904675-14">}</span><span class="p" data-group-id="6771904675-13">}</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>In state <code class="inline">locked</code>, when a button is pressed, it is collected with the
│ │ │ │  previously pressed buttons up to the length of the correct code, then
│ │ │ │  compared with the correct code. Depending on the result, the door is
│ │ │ │  either unlocked and the <code class="inline">gen_statem</code> goes to state <code class="inline">open</code>, or the door
│ │ │ │  remains in state <code class="inline">locked</code>.</p><p>When changing to state <code class="inline">open</code>, the collected buttons are reset, the lock
│ │ │ │ -unlocked, and a <em>state time-out</em> for 10 seconds is started.</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="7416743424-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7416743424-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7416743424-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7416743424-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7416743424-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7416743424-3">}</span><span class="p">.</span></code></pre><p>In state <code class="inline">open</code>, a button event is ignored by staying in the same state.
│ │ │ │ +unlocked, and a <em>state time-out</em> for 10 seconds is started.</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="9364758994-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9364758994-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9364758994-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9364758994-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9364758994-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9364758994-3">}</span><span class="p">.</span></code></pre><p>In state <code class="inline">open</code>, a button event is ignored by staying in the same state.
│ │ │ │  This can also be done by returning <code class="inline">{keep_state, Data}</code>, or in this case
│ │ │ │  since <code class="inline">Data</code> is unchanged, by returning <code class="inline">keep_state_and_data</code>.</p><h2 id="state-time-outs" class="section-heading">
│ │ │ │    <a href="#state-time-outs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">State Time-Outs</span>
│ │ │ │  </h2>
│ │ │ │  <p>When a correct code has been given, the door is unlocked and the following
│ │ │ │ -tuple is returned from <code class="inline">locked/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1944930396-1">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1944930396-2">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="1944930396-3">[</span><span class="p" data-group-id="1944930396-3">]</span><span class="p" data-group-id="1944930396-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1944930396-4">[</span><span class="p" data-group-id="1944930396-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="1944930396-5">}</span><span class="p" data-group-id="1944930396-4">]</span><span class="p" data-group-id="1944930396-1">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span></code></pre><p>10,000 is a time-out value in milliseconds. After this time (10 seconds),
│ │ │ │ +tuple is returned from <code class="inline">locked/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2657337223-1">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2657337223-2">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="2657337223-3">[</span><span class="p" data-group-id="2657337223-3">]</span><span class="p" data-group-id="2657337223-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2657337223-4">[</span><span class="p" data-group-id="2657337223-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="2657337223-5">}</span><span class="p" data-group-id="2657337223-4">]</span><span class="p" data-group-id="2657337223-1">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span></code></pre><p>10,000 is a time-out value in milliseconds. After this time (10 seconds),
│ │ │ │  a time-out occurs. Then, <code class="inline">StateName(state_timeout, lock, Data)</code> is called.
│ │ │ │  The time-out occurs when the door has been in state <code class="inline">open</code> for 10 seconds.
│ │ │ │ -After that the door is locked again:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="7003584304-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="7003584304-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="7003584304-2">(</span><span class="p" data-group-id="7003584304-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7003584304-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7003584304-3">}</span><span class="p">;</span></code></pre><p>The timer for a <em>state time-out</em> is automatically canceled when
│ │ │ │ +After that the door is locked again:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="8335301955-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="8335301955-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="8335301955-2">(</span><span class="p" data-group-id="8335301955-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8335301955-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8335301955-3">}</span><span class="p">;</span></code></pre><p>The timer for a <em>state time-out</em> is automatically canceled when
│ │ │ │  the state machine does a <em>state change</em>.</p><p>You can restart, cancel, or update a <em>state time-out</em>. See section
│ │ │ │  <a href="#time-outs"><em>Time-Outs</em></a> for details.</p><h2 id="all-state-events" class="section-heading">
│ │ │ │    <a href="#all-state-events" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">All State Events</span>
│ │ │ │  </h2>
│ │ │ │  <p>Sometimes events can arrive in any state of the <code class="inline">gen_statem</code>. It is convenient
│ │ │ │  to handle these in a common state handler function that all state functions
│ │ │ │  call for events not specific to the state.</p><p>Consider a <code class="inline">code_length/0</code> function that returns the length
│ │ │ │  of the correct code.  We dispatch all events that are not state-specific
│ │ │ │  to the common function <code class="inline">handle_common/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4766901854-1">(</span><span class="p" data-group-id="4766901854-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="4766901854-2">]</span><span class="p" data-group-id="4766901854-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1366242689-1">(</span><span class="p" data-group-id="1366242689-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1366242689-2">]</span><span class="p" data-group-id="1366242689-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">code_length</span><span class="p" data-group-id="4766901854-3">(</span><span class="p" data-group-id="4766901854-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="4766901854-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="4766901854-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">code_length</span><span class="p" data-group-id="1366242689-3">(</span><span class="p" data-group-id="1366242689-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="1366242689-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="1366242689-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="4766901854-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4766901854-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="4766901854-6">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4766901854-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">handle_common</span><span class="p" data-group-id="4766901854-7">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4766901854-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="1366242689-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1366242689-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="1366242689-6">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1366242689-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">handle_common</span><span class="p" data-group-id="1366242689-7">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1366242689-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="4766901854-8">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4766901854-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="4766901854-9">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4766901854-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">handle_common</span><span class="p" data-group-id="4766901854-10">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4766901854-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="4766901854-11">(</span><span class="p" data-group-id="4766901854-12">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="4766901854-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4766901854-13">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="4766901854-13">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4766901854-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4766901854-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="4766901854-15">[</span><span class="p" data-group-id="4766901854-16">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="4766901854-17">(</span><span class="n">Code</span><span class="p" data-group-id="4766901854-17">)</span><span class="p" data-group-id="4766901854-16">}</span><span class="p" data-group-id="4766901854-15">]</span><span class="p" data-group-id="4766901854-14">}</span><span class="p">.</span></code></pre><p>Another way to do it is through a convenience macro <code class="inline">?HANDLE_COMMON/0</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8705593930-1">(</span><span class="p" data-group-id="8705593930-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8705593930-2">]</span><span class="p" data-group-id="8705593930-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1366242689-8">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1366242689-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1366242689-9">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1366242689-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">handle_common</span><span class="p" data-group-id="1366242689-10">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1366242689-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="1366242689-11">(</span><span class="p" data-group-id="1366242689-12">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="1366242689-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1366242689-13">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="1366242689-13">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1366242689-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1366242689-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="1366242689-15">[</span><span class="p" data-group-id="1366242689-16">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="1366242689-17">(</span><span class="n">Code</span><span class="p" data-group-id="1366242689-17">)</span><span class="p" data-group-id="1366242689-16">}</span><span class="p" data-group-id="1366242689-15">]</span><span class="p" data-group-id="1366242689-14">}</span><span class="p">.</span></code></pre><p>Another way to do it is through a convenience macro <code class="inline">?HANDLE_COMMON/0</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7078239866-1">(</span><span class="p" data-group-id="7078239866-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7078239866-2">]</span><span class="p" data-group-id="7078239866-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">code_length</span><span class="p" data-group-id="8705593930-3">(</span><span class="p" data-group-id="8705593930-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="8705593930-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="8705593930-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">code_length</span><span class="p" data-group-id="7078239866-3">(</span><span class="p" data-group-id="7078239866-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="7078239866-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="7078239866-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="8705593930-5">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="8705593930-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="8705593930-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="8705593930-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="8705593930-7">)</span><span class="p" data-group-id="8705593930-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7078239866-5">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="7078239866-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="7078239866-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="7078239866-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="7078239866-7">)</span><span class="p" data-group-id="7078239866-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="8705593930-8">(</span><span class="p" data-group-id="8705593930-9">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="8705593930-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8705593930-10">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="8705593930-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8705593930-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8705593930-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="8705593930-12">[</span><span class="p" data-group-id="8705593930-13">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="8705593930-14">(</span><span class="n">Code</span><span class="p" data-group-id="8705593930-14">)</span><span class="p" data-group-id="8705593930-13">}</span><span class="p" data-group-id="8705593930-12">]</span><span class="p" data-group-id="8705593930-11">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="7078239866-8">(</span><span class="p" data-group-id="7078239866-9">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="7078239866-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7078239866-10">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="7078239866-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7078239866-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7078239866-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="7078239866-12">[</span><span class="p" data-group-id="7078239866-13">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="7078239866-14">(</span><span class="n">Code</span><span class="p" data-group-id="7078239866-14">)</span><span class="p" data-group-id="7078239866-13">}</span><span class="p" data-group-id="7078239866-12">]</span><span class="p" data-group-id="7078239866-11">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="8705593930-15">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="8705593930-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="7078239866-15">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7078239866-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="8705593930-16">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="8705593930-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="7078239866-16">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7078239866-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span></code></pre><p>This example uses <a href="../../../lib/stdlib/doc/html/gen_statem.html#call/2"><code class="inline">gen_statem:call/2</code></a>, which waits for a reply from the server.
│ │ │ │  The reply is sent with a <code class="inline">{reply, From, Reply}</code> tuple in an action list in the
│ │ │ │  <code class="inline">{keep_state, ...}</code> tuple that retains the current state. This return form is
│ │ │ │  convenient when you want to stay in the current state but do not know or care
│ │ │ │  about what it is.</p><p>If the common <em>state callback</em> needs to know the current state a function
│ │ │ │ -<code class="inline">handle_common/4</code> can be used instead:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="8180260962-1">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="8180260962-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="8180260962-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="8180260962-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="8180260962-3">)</span><span class="p" data-group-id="8180260962-1">)</span><span class="p">.</span></code></pre><h2 id="one-state-callback" class="section-heading">
│ │ │ │ +<code class="inline">handle_common/4</code> can be used instead:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7517953943-1">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="7517953943-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="7517953943-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="7517953943-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="7517953943-3">)</span><span class="p" data-group-id="7517953943-1">)</span><span class="p">.</span></code></pre><h2 id="one-state-callback" class="section-heading">
│ │ │ │    <a href="#one-state-callback" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">One State Callback</span>
│ │ │ │  </h2>
│ │ │ │  <p>If <a href="#callback-modes"><em>callback mode</em></a> <code class="inline">handle_event_function</code> is used,
│ │ │ │  all events are handled in
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#c:handle_event/4"><code class="inline">Module:handle_event/4</code></a> and we can
│ │ │ │  (but do not have to) use an event-centered approach where we first branch
│ │ │ │  depending on event and then depending on state:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3375510701-1">(</span><span class="p" data-group-id="3375510701-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="3375510701-2">]</span><span class="p" data-group-id="3375510701-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9114518509-1">(</span><span class="p" data-group-id="9114518509-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="9114518509-2">]</span><span class="p" data-group-id="9114518509-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="3375510701-3">(</span><span class="p" data-group-id="3375510701-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="9114518509-3">(</span><span class="p" data-group-id="9114518509-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">handle_event_function</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="3375510701-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3375510701-5">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="3375510701-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3375510701-6">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="3375510701-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3375510701-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="9114518509-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9114518509-5">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9114518509-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9114518509-6">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="9114518509-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9114518509-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">State</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │  	</span><span class="ss">locked</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="3375510701-7">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="3375510701-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9114518509-7">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="9114518509-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │                  </span><span class="k">if</span><span class="w">
│ │ │ │ -                    </span><span class="nf">length</span><span class="p" data-group-id="3375510701-8">(</span><span class="n">Buttons</span><span class="p" data-group-id="3375510701-8">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                    </span><span class="nf">length</span><span class="p" data-group-id="9114518509-8">(</span><span class="n">Buttons</span><span class="p" data-group-id="9114518509-8">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                          </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │ │                      </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                        </span><span class="nf">tl</span><span class="p" data-group-id="3375510701-9">(</span><span class="n">Buttons</span><span class="p" data-group-id="3375510701-9">)</span><span class="w">
│ │ │ │ -                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="3375510701-10">[</span><span class="n">Button</span><span class="p" data-group-id="3375510701-10">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                        </span><span class="nf">tl</span><span class="p" data-group-id="9114518509-9">(</span><span class="n">Buttons</span><span class="p" data-group-id="9114518509-9">)</span><span class="w">
│ │ │ │ +                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9114518509-10">[</span><span class="n">Button</span><span class="p" data-group-id="9114518509-10">]</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="k">if</span><span class="w">
│ │ │ │                  </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="3375510701-11">(</span><span class="p" data-group-id="3375510701-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="p" data-group-id="3375510701-12">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3375510701-13">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="3375510701-14">[</span><span class="p" data-group-id="3375510701-14">]</span><span class="p" data-group-id="3375510701-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                     </span><span class="p" data-group-id="3375510701-15">[</span><span class="p" data-group-id="3375510701-16">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="3375510701-16">}</span><span class="p" data-group-id="3375510701-15">]</span><span class="p" data-group-id="3375510701-12">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="9114518509-11">(</span><span class="p" data-group-id="9114518509-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="p" data-group-id="9114518509-12">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9114518509-13">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9114518509-14">[</span><span class="p" data-group-id="9114518509-14">]</span><span class="p" data-group-id="9114518509-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                     </span><span class="p" data-group-id="9114518509-15">[</span><span class="p" data-group-id="9114518509-16">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="9114518509-16">}</span><span class="p" data-group-id="9114518509-15">]</span><span class="p" data-group-id="9114518509-12">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │                  </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -                    </span><span class="p" data-group-id="3375510701-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3375510701-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="3375510701-18">}</span><span class="p" data-group-id="3375510701-17">}</span><span class="w">
│ │ │ │ +                    </span><span class="p" data-group-id="9114518509-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9114518509-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="9114518509-18">}</span><span class="p" data-group-id="9114518509-17">}</span><span class="w">
│ │ │ │              </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">open</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="3375510701-19">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3375510701-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="3375510701-20">(</span><span class="p" data-group-id="3375510701-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3375510701-21">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3375510701-21">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="3375510701-22">(</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="3375510701-23">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="3375510701-23">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3375510701-24">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="3375510701-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3375510701-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3375510701-25">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="3375510701-26">[</span><span class="p" data-group-id="3375510701-27">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="3375510701-28">(</span><span class="n">Code</span><span class="p" data-group-id="3375510701-28">)</span><span class="p" data-group-id="3375510701-27">}</span><span class="p" data-group-id="3375510701-26">]</span><span class="p" data-group-id="3375510701-25">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="9114518509-19">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9114518509-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="9114518509-20">(</span><span class="p" data-group-id="9114518509-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9114518509-21">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9114518509-21">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="9114518509-22">(</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9114518509-23">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="9114518509-23">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9114518509-24">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="9114518509-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9114518509-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9114518509-25">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="9114518509-26">[</span><span class="p" data-group-id="9114518509-27">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="9114518509-28">(</span><span class="n">Code</span><span class="p" data-group-id="9114518509-28">)</span><span class="p" data-group-id="9114518509-27">}</span><span class="p" data-group-id="9114518509-26">]</span><span class="p" data-group-id="9114518509-25">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="stopping" class="section-heading">
│ │ │ │    <a href="#stopping" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Stopping</span>
│ │ │ │  </h2>
│ │ │ │ @@ -668,59 +668,59 @@
│ │ │ │  </h3>
│ │ │ │  <p>If the <code class="inline">gen_statem</code> is part of a supervision tree, no stop function is needed.
│ │ │ │  The <code class="inline">gen_statem</code> is automatically terminated by its supervisor. Exactly how
│ │ │ │  this is done is defined by a <a href="sup_princ.xhtml#shutdown">shutdown strategy</a>
│ │ │ │  set in the supervisor.</p><p>If it is necessary to clean up before termination, the shutdown strategy
│ │ │ │  must be a time-out value and the <code class="inline">gen_statem</code> must in function <code class="inline">init/1</code>
│ │ │ │  set itself to trap exit signals by calling
│ │ │ │ -<a href="../../../lib/../erts/doc/html/erlang.html#process_flag/2"><code class="inline">process_flag(trap_exit, true)</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="7635413432-1">(</span><span class="n">Args</span><span class="p" data-group-id="7635413432-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="7635413432-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="7635413432-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="7635413432-3">(</span><span class="p" data-group-id="7635413432-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +<a href="../../../lib/../erts/doc/html/erlang.html#process_flag/2"><code class="inline">process_flag(trap_exit, true)</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="2456674994-1">(</span><span class="n">Args</span><span class="p" data-group-id="2456674994-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="2456674994-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2456674994-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="2456674994-3">(</span><span class="p" data-group-id="2456674994-3">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>When ordered to shut down, the <code class="inline">gen_statem</code> then calls callback function
│ │ │ │  <code class="inline">terminate(shutdown, State, Data)</code>.</p><p>In this example, function <code class="inline">terminate/3</code> locks the door if it is open,
│ │ │ │  so we do not accidentally leave the door open
│ │ │ │ -when the supervision tree terminates:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="9568792834-1">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="9568792834-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="9568792834-2">(</span><span class="p" data-group-id="9568792834-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +when the supervision tree terminates:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="8330069246-1">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="8330069246-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="8330069246-2">(</span><span class="p" data-group-id="8330069246-2">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h3 id="standalone-gen_statem" class="section-heading">
│ │ │ │    <a href="#standalone-gen_statem" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Standalone gen_statem</span>
│ │ │ │  </h3>
│ │ │ │  <p>If the <code class="inline">gen_statem</code> is not part of a supervision tree, it can be stopped
│ │ │ │  using <a href="../../../lib/stdlib/doc/html/gen_statem.html#stop/1"><code class="inline">gen_statem:stop/1</code></a>, preferably through
│ │ │ │  an API function:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7352621219-1">(</span><span class="p" data-group-id="7352621219-2">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7352621219-2">]</span><span class="p" data-group-id="7352621219-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0171778410-1">(</span><span class="p" data-group-id="0171778410-2">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0171778410-2">]</span><span class="p" data-group-id="0171778410-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="7352621219-3">(</span><span class="p" data-group-id="7352621219-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="7352621219-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="7352621219-4">)</span><span class="p">.</span></code></pre><p>This makes the <code class="inline">gen_statem</code> call callback function <code class="inline">terminate/3</code> just like
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="0171778410-3">(</span><span class="p" data-group-id="0171778410-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="0171778410-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="0171778410-4">)</span><span class="p">.</span></code></pre><p>This makes the <code class="inline">gen_statem</code> call callback function <code class="inline">terminate/3</code> just like
│ │ │ │  for a supervised server and waits for the process to terminate.</p><h2 id="event-time-outs" class="section-heading">
│ │ │ │    <a href="#event-time-outs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Event Time-Outs</span>
│ │ │ │  </h2>
│ │ │ │  <p>A time-out feature inherited from <code class="inline">gen_statem</code>'s predecessor <a href="../../../lib/stdlib/doc/html/gen_fsm.html"><code class="inline">gen_fsm</code></a>,
│ │ │ │  is an <em>event time-out</em>, that is, if an event arrives the timer is canceled.
│ │ │ │  You get either an event or a time-out, but not both.</p><p>It is ordered by the
│ │ │ │  <a href="#transition-actions"><em>transition action</em></a> <code class="inline">{timeout, Time, EventContent}</code>,
│ │ │ │  or just an integer <code class="inline">Time</code>, even without the enclosing actions list (the latter
│ │ │ │  is a form inherited from <code class="inline">gen_fsm</code>).</p><p>This type of time-out is useful, for example, to act on inactivity.
│ │ │ │  Let's restart the code sequence if no button is pressed for say 30 seconds:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="6808807897-1">(</span><span class="ss">timeout</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6808807897-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6808807897-2">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6808807897-3">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6808807897-4">[</span><span class="p" data-group-id="6808807897-4">]</span><span class="p" data-group-id="6808807897-3">}</span><span class="p" data-group-id="6808807897-2">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="6808807897-5">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6808807897-6">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6808807897-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="6808807897-7">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="6808807897-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6808807897-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="9427683158-1">(</span><span class="ss">timeout</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9427683158-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9427683158-2">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9427683158-3">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9427683158-4">[</span><span class="p" data-group-id="9427683158-4">]</span><span class="p" data-group-id="9427683158-3">}</span><span class="p" data-group-id="9427683158-2">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="9427683158-5">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9427683158-6">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9427683158-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9427683158-7">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="9427683158-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9427683158-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6808807897-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6808807897-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="6808807897-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p" data-group-id="6808807897-8">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9427683158-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9427683158-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="9427683158-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p" data-group-id="9427683158-8">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Whenever we receive a button event we start an <em>event time-out</em> of 30 seconds,
│ │ │ │  and if we get an <em>event type</em> of <code class="inline">timeout</code> we reset the remaining
│ │ │ │  code sequence.</p><p>An <em>event time-out</em> is canceled by any other event so you either get
│ │ │ │  some other event or the time-out event. Therefore, canceling,
│ │ │ │  restarting, or updating an <em>event time-out</em> is neither possible nor
│ │ │ │  necessary. Whatever event you act on has already canceled
│ │ │ │  the <em>event time-out</em>, so there is never a running <em>event time-out</em>
│ │ │ │ @@ -739,30 +739,30 @@
│ │ │ │  another, maybe cancel the time-out without changing states, or perhaps run
│ │ │ │  multiple time-outs in parallel. All this can be accomplished with
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#t:generic_timeout/0"><em>generic time-outs</em></a>. They may look a little
│ │ │ │  bit like <a href="../../../lib/stdlib/doc/html/gen_statem.html#t:event_timeout/0"><em>event time-outs</em></a> but contain
│ │ │ │  a name to allow for any number of them simultaneously and they are
│ │ │ │  not automatically canceled.</p><p>Here is how to accomplish the <em>state time-out</em> in the previous example
│ │ │ │  by instead using a <em>generic time-out</em> named for example <code class="inline">open</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="7235652654-1">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7235652654-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7235652654-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7235652654-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="7235652654-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7235652654-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="1459861150-1">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1459861150-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1459861150-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="1459861150-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="1459861150-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1459861150-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="7235652654-4">(</span><span class="p" data-group-id="7235652654-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="7235652654-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7235652654-6">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="7235652654-7">[</span><span class="p" data-group-id="7235652654-7">]</span><span class="p" data-group-id="7235652654-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="7235652654-8">[</span><span class="p" data-group-id="7235652654-9">{</span><span class="p" data-group-id="7235652654-10">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="7235652654-10">}</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="7235652654-9">}</span><span class="p" data-group-id="7235652654-8">]</span><span class="p" data-group-id="7235652654-5">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="1459861150-4">(</span><span class="p" data-group-id="1459861150-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="1459861150-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1459861150-6">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="1459861150-7">[</span><span class="p" data-group-id="1459861150-7">]</span><span class="p" data-group-id="1459861150-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="1459861150-8">[</span><span class="p" data-group-id="1459861150-9">{</span><span class="p" data-group-id="1459861150-10">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="1459861150-10">}</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="1459861150-9">}</span><span class="p" data-group-id="1459861150-8">]</span><span class="p" data-group-id="1459861150-5">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="7235652654-11">(</span><span class="p" data-group-id="7235652654-12">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="7235652654-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7235652654-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="7235652654-13">(</span><span class="p" data-group-id="7235652654-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7235652654-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="7235652654-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="7235652654-15">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7235652654-16">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7235652654-16">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7235652654-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7235652654-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="7235652654-17">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1459861150-11">(</span><span class="p" data-group-id="1459861150-12">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="1459861150-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1459861150-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="1459861150-13">(</span><span class="p" data-group-id="1459861150-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1459861150-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="1459861150-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1459861150-15">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1459861150-16">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="1459861150-16">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1459861150-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1459861150-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="1459861150-17">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Specific <em>generic time-outs</em> can just as <a href="#state-time-outs"><em>state time-outs</em></a>
│ │ │ │  be restarted or canceled by setting it to a new time or <code class="inline">infinity</code>.</p><p>In this particular case we do not need to cancel the time-out since
│ │ │ │  the time-out event is the only possible reason to do a <em>state change</em>
│ │ │ │  from <code class="inline">open</code> to <code class="inline">locked</code>.</p><p>Instead of bothering with when to cancel a time-out, a late time-out event
│ │ │ │  can be handled by ignoring it if it arrives in a state
│ │ │ │  where it is known to be late.</p><p>You can restart, cancel, or update a <em>generic time-out</em>.
│ │ │ │  See section <a href="#time-outs"><em>Time-Outs</em></a> for details.</p><h2 id="erlang-timers" class="section-heading">
│ │ │ │ @@ -774,32 +774,32 @@
│ │ │ │  <p>The most versatile way to handle time-outs is to use Erlang Timers; see
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#start_timer/4"><code class="inline">erlang:start_timer/3,4</code></a>. Most time-out tasks
│ │ │ │  can be performed with the time-out features in <a href="../../../lib/stdlib/doc/html/gen_statem.html"><code class="inline">gen_statem</code></a>,
│ │ │ │  but an example of one that cannot is if you should need the return value
│ │ │ │  from <a href="../../../lib/../erts/doc/html/erlang.html#cancel_timer/2"><code class="inline">erlang:cancel_timer(Tref)</code></a>, that is,
│ │ │ │  the remaining time of the timer.</p><p>Here is how to accomplish the <em>state time-out</em> in the previous example
│ │ │ │  by instead using an Erlang Timer:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="2284006997-1">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2284006997-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2284006997-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2284006997-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="2284006997-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2284006997-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="9990888525-1">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9990888525-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9990888525-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9990888525-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="9990888525-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9990888525-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="2284006997-4">(</span><span class="p" data-group-id="2284006997-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="9990888525-4">(</span><span class="p" data-group-id="9990888525-4">)</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="n">Tref</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │ -                 </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">start_timer</span><span class="p" data-group-id="2284006997-5">(</span><span class="w">
│ │ │ │ -                     </span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2284006997-6">(</span><span class="p" data-group-id="2284006997-6">)</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p" data-group-id="2284006997-5">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="2284006997-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2284006997-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="2284006997-9">[</span><span class="p" data-group-id="2284006997-9">]</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="2284006997-8">}</span><span class="p" data-group-id="2284006997-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +                 </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">start_timer</span><span class="p" data-group-id="9990888525-5">(</span><span class="w">
│ │ │ │ +                     </span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="9990888525-6">(</span><span class="p" data-group-id="9990888525-6">)</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p" data-group-id="9990888525-5">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9990888525-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9990888525-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9990888525-9">[</span><span class="p" data-group-id="9990888525-9">]</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="9990888525-8">}</span><span class="p" data-group-id="9990888525-7">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="2284006997-10">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2284006997-11">{</span><span class="ss">timeout</span><span class="p">,</span><span class="n">Tref</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="2284006997-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2284006997-12">#{</span><span class="ss">timer</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="2284006997-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2284006997-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="2284006997-13">(</span><span class="p" data-group-id="2284006997-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2284006997-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="2284006997-15">(</span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2284006997-15">)</span><span class="p" data-group-id="2284006997-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="2284006997-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2284006997-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="2284006997-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2284006997-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2284006997-18">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="2284006997-18">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="9990888525-10">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9990888525-11">{</span><span class="ss">timeout</span><span class="p">,</span><span class="n">Tref</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="9990888525-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9990888525-12">#{</span><span class="ss">timer</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="9990888525-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9990888525-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="9990888525-13">(</span><span class="p" data-group-id="9990888525-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9990888525-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="9990888525-15">(</span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9990888525-15">)</span><span class="p" data-group-id="9990888525-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="9990888525-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9990888525-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9990888525-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9990888525-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9990888525-18">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="9990888525-18">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Removing the <code class="inline">timer</code> key from the map when we do a <em>state change</em> to <code class="inline">locked</code>
│ │ │ │  is not strictly necessary since we can only get into state <code class="inline">open</code>
│ │ │ │  with an updated <code class="inline">timer</code> map value. But it can be nice to not have
│ │ │ │  outdated values in the state <code class="inline">Data</code>.</p><p>If you need to cancel a timer because of some other event, you can use
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#cancel_timer/2"><code class="inline">erlang:cancel_timer(Tref)</code></a>. Note that no time-out
│ │ │ │  message will arrive after this (because the timer has been
│ │ │ │  explicitly canceled), unless you have already postponed one earlier
│ │ │ │ @@ -815,16 +815,16 @@
│ │ │ │    <span class="text">Postponing Events</span>
│ │ │ │  </h2>
│ │ │ │  <p>If you want to ignore a particular event in the current state and handle it
│ │ │ │  in a future state, you can postpone the event. A postponed event
│ │ │ │  is retried after a <em>state change</em>, that is, <code class="inline">OldState =/= NewState</code>.</p><p>Postponing is ordered by the
│ │ │ │  <a href="#transition-actions"><em>transition action</em></a> <code class="inline">postpone</code>.</p><p>In this example, instead of ignoring button events while in the <code class="inline">open</code> state,
│ │ │ │  we can postpone them handle them later in the <code class="inline">locked</code> state:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="3079383385-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3079383385-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="3079383385-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3079383385-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3079383385-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="3079383385-4">[</span><span class="ss">postpone</span><span class="p" data-group-id="3079383385-4">]</span><span class="p" data-group-id="3079383385-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="5584359964-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5584359964-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5584359964-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5584359964-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5584359964-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="5584359964-4">[</span><span class="ss">postpone</span><span class="p" data-group-id="5584359964-4">]</span><span class="p" data-group-id="5584359964-3">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Since a postponed event is only retried after a <em>state change</em>, you have to
│ │ │ │  think about where to keep a state data item. You can keep it in the server
│ │ │ │  <code class="inline">Data</code> or in the <code class="inline">State</code> itself, for example by having two more or less
│ │ │ │  identical states to keep a boolean value, or by using a complex state (see
│ │ │ │  section <a href="#complex-state"><em>Complex State</em></a>) with
│ │ │ │  <a href="#callback-modes"><em>callback mode</em></a>
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#t:callback_mode/0"><code class="inline">handle_event_function</code></a>. If a change
│ │ │ │ @@ -845,55 +845,55 @@
│ │ │ │    <a href="#selective-receive" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Selective Receive</span>
│ │ │ │  </h3>
│ │ │ │  <p>Erlang's selective <code class="inline">receive</code> statement is often used to describe simple state
│ │ │ │  machine examples in straightforward Erlang code. The following is a possible
│ │ │ │ -implementation of the first example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4325032350-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="4325032350-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="4325032350-2">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_1</span><span class="p" data-group-id="4325032350-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4325032350-3">(</span><span class="p" data-group-id="4325032350-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4325032350-4">]</span><span class="p" data-group-id="4325032350-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="4325032350-5">(</span><span class="n">Code</span><span class="p" data-group-id="4325032350-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="4325032350-6">(</span><span class="w">
│ │ │ │ -      </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="4325032350-7">(</span><span class="p" data-group-id="4325032350-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">register</span><span class="p" data-group-id="4325032350-8">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4325032350-9">(</span><span class="p" data-group-id="4325032350-9">)</span><span class="p" data-group-id="4325032350-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -	      </span><span class="nf">do_lock</span><span class="p" data-group-id="4325032350-10">(</span><span class="p" data-group-id="4325032350-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -	      </span><span class="nf">locked</span><span class="p" data-group-id="4325032350-11">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="4325032350-12">(</span><span class="n">Code</span><span class="p" data-group-id="4325032350-12">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4325032350-13">[</span><span class="p" data-group-id="4325032350-13">]</span><span class="p" data-group-id="4325032350-11">)</span><span class="w">
│ │ │ │ -      </span><span class="k">end</span><span class="p" data-group-id="4325032350-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +implementation of the first example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5038392091-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="5038392091-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5038392091-2">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_1</span><span class="p" data-group-id="5038392091-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5038392091-3">(</span><span class="p" data-group-id="5038392091-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5038392091-4">]</span><span class="p" data-group-id="5038392091-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="5038392091-5">(</span><span class="n">Code</span><span class="p" data-group-id="5038392091-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="5038392091-6">(</span><span class="w">
│ │ │ │ +      </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="5038392091-7">(</span><span class="p" data-group-id="5038392091-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">register</span><span class="p" data-group-id="5038392091-8">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5038392091-9">(</span><span class="p" data-group-id="5038392091-9">)</span><span class="p" data-group-id="5038392091-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +	      </span><span class="nf">do_lock</span><span class="p" data-group-id="5038392091-10">(</span><span class="p" data-group-id="5038392091-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +	      </span><span class="nf">locked</span><span class="p" data-group-id="5038392091-11">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="5038392091-12">(</span><span class="n">Code</span><span class="p" data-group-id="5038392091-12">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5038392091-13">[</span><span class="p" data-group-id="5038392091-13">]</span><span class="p" data-group-id="5038392091-11">)</span><span class="w">
│ │ │ │ +      </span><span class="k">end</span><span class="p" data-group-id="5038392091-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">button</span><span class="p" data-group-id="4325032350-14">(</span><span class="n">Button</span><span class="p" data-group-id="4325032350-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="o">?</span><span class="n">NAME</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4325032350-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4325032350-15">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="2662811003-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="2662811003-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">button</span><span class="p" data-group-id="5038392091-14">(</span><span class="n">Button</span><span class="p" data-group-id="5038392091-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="o">?</span><span class="n">NAME</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5038392091-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5038392091-15">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="7582546080-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="7582546080-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="2662811003-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2662811003-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7582546080-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7582546080-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │                  </span><span class="k">if</span><span class="w">
│ │ │ │ -                    </span><span class="nf">length</span><span class="p" data-group-id="2662811003-3">(</span><span class="n">Buttons</span><span class="p" data-group-id="2662811003-3">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                    </span><span class="nf">length</span><span class="p" data-group-id="7582546080-3">(</span><span class="n">Buttons</span><span class="p" data-group-id="7582546080-3">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                          </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │ │                      </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                        </span><span class="nf">tl</span><span class="p" data-group-id="2662811003-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="2662811003-4">)</span><span class="w">
│ │ │ │ -                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="2662811003-5">[</span><span class="n">Button</span><span class="p" data-group-id="2662811003-5">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                        </span><span class="nf">tl</span><span class="p" data-group-id="7582546080-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="7582546080-4">)</span><span class="w">
│ │ │ │ +                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="7582546080-5">[</span><span class="n">Button</span><span class="p" data-group-id="7582546080-5">]</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="k">if</span><span class="w">
│ │ │ │                  </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="2662811003-6">(</span><span class="p" data-group-id="2662811003-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -		    </span><span class="nf">open</span><span class="p" data-group-id="2662811003-7">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="2662811003-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ +                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="7582546080-6">(</span><span class="p" data-group-id="7582546080-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +		    </span><span class="nf">open</span><span class="p" data-group-id="7582546080-7">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="7582546080-7">)</span><span class="p">;</span><span class="w">
│ │ │ │                  </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -                    </span><span class="nf">locked</span><span class="p" data-group-id="2662811003-8">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="2662811003-8">)</span><span class="w">
│ │ │ │ +                    </span><span class="nf">locked</span><span class="p" data-group-id="7582546080-8">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="7582546080-8">)</span><span class="w">
│ │ │ │              </span><span class="k">end</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="2213337332-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="2213337332-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="2456646403-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="2456646403-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -	    </span><span class="nf">do_lock</span><span class="p" data-group-id="2213337332-2">(</span><span class="p" data-group-id="2213337332-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -	    </span><span class="nf">locked</span><span class="p" data-group-id="2213337332-3">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2213337332-4">[</span><span class="p" data-group-id="2213337332-4">]</span><span class="p" data-group-id="2213337332-3">)</span><span class="w">
│ │ │ │ +	    </span><span class="nf">do_lock</span><span class="p" data-group-id="2456646403-2">(</span><span class="p" data-group-id="2456646403-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="nf">locked</span><span class="p" data-group-id="2456646403-3">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2456646403-4">[</span><span class="p" data-group-id="2456646403-4">]</span><span class="p" data-group-id="2456646403-3">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">do_lock</span><span class="p" data-group-id="2213337332-5">(</span><span class="p" data-group-id="2213337332-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2213337332-6">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2213337332-7">[</span><span class="p" data-group-id="2213337332-7">]</span><span class="p" data-group-id="2213337332-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="2213337332-8">(</span><span class="p" data-group-id="2213337332-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2213337332-9">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2213337332-10">[</span><span class="p" data-group-id="2213337332-10">]</span><span class="p" data-group-id="2213337332-9">)</span><span class="p">.</span></code></pre><p>The selective receive in this case causes <code class="inline">open</code> to implicitly postpone any
│ │ │ │ +</span><span class="nf">do_lock</span><span class="p" data-group-id="2456646403-5">(</span><span class="p" data-group-id="2456646403-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2456646403-6">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2456646403-7">[</span><span class="p" data-group-id="2456646403-7">]</span><span class="p" data-group-id="2456646403-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="2456646403-8">(</span><span class="p" data-group-id="2456646403-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2456646403-9">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2456646403-10">[</span><span class="p" data-group-id="2456646403-10">]</span><span class="p" data-group-id="2456646403-9">)</span><span class="p">.</span></code></pre><p>The selective receive in this case causes <code class="inline">open</code> to implicitly postpone any
│ │ │ │  events to the <code class="inline">locked</code> state.</p><p>A catch-all receive should never be used from a <code class="inline">gen_statem</code> behaviour
│ │ │ │  (or from any <code class="inline">gen_*</code> behaviour), as the receive statement is within
│ │ │ │  the <code class="inline">gen_*</code> engine itself. <a href="../../../lib/stdlib/doc/html/sys.html"><code class="inline">sys</code></a>-compatible behaviours must respond to
│ │ │ │  system messages and therefore do that in their engine receive loop,
│ │ │ │  passing non-system messages to the <em>callback module</em>. Using a catch-all
│ │ │ │  receive can result in system messages being discarded, which in turn
│ │ │ │  can lead to unexpected behaviour. If a selective receive must be used,
│ │ │ │ @@ -916,40 +916,40 @@
│ │ │ │  section), especially if only one or a few states have state enter actions,
│ │ │ │  this is a perfect use case for the built in
│ │ │ │  <a href="#state-enter-calls"><em>state enter calls</em></a>.</p><p>You return a list containing <code class="inline">state_enter</code> from your
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#c:callback_mode/0"><code class="inline">callback_mode/0</code></a> function and the
│ │ │ │  <code class="inline">gen_statem</code> engine will call your <em>state callback</em> once with an event
│ │ │ │  <code class="inline">(enter, OldState, ...)</code> whenever it does a <em>state change</em>. Then you
│ │ │ │  just need to handle these event-like calls in all states.</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="2088873292-1">(</span><span class="n">Code</span><span class="p" data-group-id="2088873292-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="2088873292-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2088873292-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2088873292-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="2088873292-4">(</span><span class="n">Code</span><span class="p" data-group-id="2088873292-4">)</span><span class="p" data-group-id="2088873292-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2088873292-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2088873292-5">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="2088873292-6">(</span><span class="p" data-group-id="2088873292-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2088873292-7">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="2088873292-7">]</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="2088873292-8">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2088873292-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="2088873292-9">(</span><span class="p" data-group-id="2088873292-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2088873292-10">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="2088873292-11">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2088873292-12">[</span><span class="p" data-group-id="2088873292-12">]</span><span class="p" data-group-id="2088873292-11">}</span><span class="p" data-group-id="2088873292-10">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="2088873292-13">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2088873292-14">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2088873292-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2088873292-15">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="2088873292-15">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2088873292-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="8400645732-1">(</span><span class="n">Code</span><span class="p" data-group-id="8400645732-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="8400645732-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8400645732-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8400645732-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="8400645732-4">(</span><span class="n">Code</span><span class="p" data-group-id="8400645732-4">)</span><span class="p" data-group-id="8400645732-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8400645732-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8400645732-5">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="8400645732-6">(</span><span class="p" data-group-id="8400645732-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8400645732-7">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="8400645732-7">]</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="8400645732-8">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8400645732-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="8400645732-9">(</span><span class="p" data-group-id="8400645732-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8400645732-10">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="8400645732-11">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8400645732-12">[</span><span class="p" data-group-id="8400645732-12">]</span><span class="p" data-group-id="8400645732-11">}</span><span class="p" data-group-id="8400645732-10">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="8400645732-13">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8400645732-14">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8400645732-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8400645732-15">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="8400645732-15">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8400645732-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="2088873292-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2088873292-16">}</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="8400645732-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8400645732-16">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="2088873292-17">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="2088873292-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="2088873292-18">(</span><span class="p" data-group-id="2088873292-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2088873292-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="2088873292-20">[</span><span class="p" data-group-id="2088873292-21">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="2088873292-21">}</span><span class="p" data-group-id="2088873292-20">]</span><span class="p" data-group-id="2088873292-19">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="2088873292-22">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2088873292-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2088873292-23">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2088873292-23">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="8400645732-17">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="8400645732-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="8400645732-18">(</span><span class="p" data-group-id="8400645732-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8400645732-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="8400645732-20">[</span><span class="p" data-group-id="8400645732-21">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="8400645732-21">}</span><span class="p" data-group-id="8400645732-20">]</span><span class="p" data-group-id="8400645732-19">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="8400645732-22">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8400645732-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8400645732-23">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8400645732-23">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>You can repeat the state enter code by returning one of
│ │ │ │  <code class="inline">{repeat_state, ...}</code>,<code class="inline">{repeat_state_and_data, _}</code>,
│ │ │ │  or <code class="inline">repeat_state_and_data</code> that otherwise behaves exactly like their
│ │ │ │  <code class="inline">keep_state</code> siblings.  See the type
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#t:state_callback_result/2"><code class="inline">state_callback_result()</code></a>
│ │ │ │  in the Reference Manual.</p><h2 id="inserted-events" class="section-heading">
│ │ │ │    <a href="#inserted-events" class="hover-link">
│ │ │ │ @@ -971,44 +971,44 @@
│ │ │ │  to dispatch pre-processed events as internal events to the main state
│ │ │ │  machine.</p><p>Using internal events also can make it easier to synchronize the state
│ │ │ │  machines.</p><p>A variant of this is to use a <a href="#complex-state">complex state</a> with
│ │ │ │  <a href="#one-state-callback">one state callback</a>, modeling the state
│ │ │ │  with, for example, a tuple <code class="inline">{MainFSMState, SubFSMState}</code>.</p><p>To illustrate this we make up an example where the buttons instead generate
│ │ │ │  down and up (press and release) events, and the lock responds
│ │ │ │  to an up event only after the corresponding down event.</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2540620118-1">(</span><span class="p" data-group-id="2540620118-2">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2540620118-2">]</span><span class="p" data-group-id="2540620118-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2753610789-1">(</span><span class="p" data-group-id="2753610789-2">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2753610789-2">]</span><span class="p" data-group-id="2753610789-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">down</span><span class="p" data-group-id="2540620118-3">(</span><span class="n">Button</span><span class="p" data-group-id="2540620118-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="2540620118-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2540620118-5">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2540620118-5">}</span><span class="p" data-group-id="2540620118-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">down</span><span class="p" data-group-id="2753610789-3">(</span><span class="n">Button</span><span class="p" data-group-id="2753610789-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="2753610789-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2753610789-5">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2753610789-5">}</span><span class="p" data-group-id="2753610789-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">up</span><span class="p" data-group-id="2540620118-6">(</span><span class="n">Button</span><span class="p" data-group-id="2540620118-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="2540620118-7">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2540620118-8">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2540620118-8">}</span><span class="p" data-group-id="2540620118-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">up</span><span class="p" data-group-id="2753610789-6">(</span><span class="n">Button</span><span class="p" data-group-id="2753610789-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="2753610789-7">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2753610789-8">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2753610789-8">}</span><span class="p" data-group-id="2753610789-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="2540620118-9">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2540620118-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="2540620118-10">(</span><span class="p" data-group-id="2540620118-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2540620118-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="2540620118-12">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2540620118-13">[</span><span class="p" data-group-id="2540620118-13">]</span><span class="p" data-group-id="2540620118-12">}</span><span class="p" data-group-id="2540620118-11">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="2540620118-14">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2540620118-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2540620118-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2540620118-16">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="2540620118-16">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2540620118-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">handle_common</span><span class="p" data-group-id="2571354611-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2571354611-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2571354611-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2571354611-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2571354611-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2571354611-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="2571354611-4">}</span><span class="p" data-group-id="2571354611-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="2571354611-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2571354611-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2571354611-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2571354611-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="2753610789-9">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2753610789-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="2753610789-10">(</span><span class="p" data-group-id="2753610789-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2753610789-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="2753610789-12">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2753610789-13">[</span><span class="p" data-group-id="2753610789-13">]</span><span class="p" data-group-id="2753610789-12">}</span><span class="p" data-group-id="2753610789-11">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="2753610789-14">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2753610789-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2753610789-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="2753610789-16">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="2753610789-16">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2753610789-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">handle_common</span><span class="p" data-group-id="8888405643-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8888405643-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8888405643-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8888405643-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8888405643-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8888405643-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="8888405643-4">}</span><span class="p" data-group-id="8888405643-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="8888405643-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8888405643-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8888405643-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8888405643-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Data</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="2571354611-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="2571354611-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="2571354611-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="2571354611-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2571354611-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="2571354611-10">[</span><span class="p" data-group-id="2571354611-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="2571354611-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2571354611-12">}</span><span class="p" data-group-id="2571354611-11">}</span><span class="p" data-group-id="2571354611-10">]</span><span class="p" data-group-id="2571354611-8">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="2571354611-13">#{</span><span class="p" data-group-id="2571354611-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8888405643-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="8888405643-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="8888405643-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="8888405643-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8888405643-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="8888405643-10">[</span><span class="p" data-group-id="8888405643-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="8888405643-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8888405643-12">}</span><span class="p" data-group-id="8888405643-11">}</span><span class="p" data-group-id="8888405643-10">]</span><span class="p" data-group-id="8888405643-8">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8888405643-13">#{</span><span class="p" data-group-id="8888405643-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="2571354611-14">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2571354611-15">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="2571354611-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2571354611-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2571354611-16">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="2571354611-17">[</span><span class="ss">postpone</span><span class="p" data-group-id="2571354611-17">]</span><span class="p" data-group-id="2571354611-16">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="8888405643-14">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8888405643-15">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8888405643-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8888405643-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8888405643-16">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="8888405643-17">[</span><span class="ss">postpone</span><span class="p" data-group-id="8888405643-17">]</span><span class="p" data-group-id="8888405643-16">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>If you start this program with <code class="inline">code_lock:start([17])</code> you can unlock with
│ │ │ │  <code class="inline">code_lock:down(17), code_lock:up(17).</code></p><h2 id="example-revisited" class="section-heading">
│ │ │ │    <a href="#example-revisited" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Example Revisited</span>
│ │ │ │  </h2>
│ │ │ │ @@ -1036,152 +1036,152 @@
│ │ │ │  Also, the state diagram does not show that the <code class="inline">code_length/0</code> call
│ │ │ │  must be handled in every state.</p><h3 id="callback-mode-state_functions" class="section-heading">
│ │ │ │    <a href="#callback-mode-state_functions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Callback Mode: state_functions</span>
│ │ │ │  </h3>
│ │ │ │ -<p>Using state functions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9559083342-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="9559083342-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9559083342-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="9559083342-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9559083342-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_2</span><span class="p" data-group-id="9559083342-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>Using state functions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1811957168-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="1811957168-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="1811957168-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="1811957168-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1811957168-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_2</span><span class="p" data-group-id="1811957168-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9559083342-4">(</span><span class="p" data-group-id="9559083342-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9559083342-5">]</span><span class="p" data-group-id="9559083342-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9559083342-6">(</span><span class="p" data-group-id="9559083342-7">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9559083342-7">]</span><span class="p" data-group-id="9559083342-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9559083342-8">(</span><span class="p" data-group-id="9559083342-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="9559083342-9">]</span><span class="p" data-group-id="9559083342-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9559083342-10">(</span><span class="p" data-group-id="9559083342-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="9559083342-11">]</span><span class="p" data-group-id="9559083342-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="9559083342-12">(</span><span class="n">Code</span><span class="p" data-group-id="9559083342-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9559083342-13">(</span><span class="p" data-group-id="9559083342-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="9559083342-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9559083342-15">[</span><span class="p" data-group-id="9559083342-15">]</span><span class="p" data-group-id="9559083342-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="9559083342-16">(</span><span class="p" data-group-id="9559083342-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="9559083342-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="9559083342-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">down</span><span class="p" data-group-id="9559083342-18">(</span><span class="n">Button</span><span class="p" data-group-id="9559083342-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="9559083342-19">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9559083342-20">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9559083342-20">}</span><span class="p" data-group-id="9559083342-19">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">up</span><span class="p" data-group-id="9559083342-21">(</span><span class="n">Button</span><span class="p" data-group-id="9559083342-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="9559083342-22">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9559083342-23">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9559083342-23">}</span><span class="p" data-group-id="9559083342-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">code_length</span><span class="p" data-group-id="9559083342-24">(</span><span class="p" data-group-id="9559083342-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="9559083342-25">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="9559083342-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="7775763822-1">(</span><span class="n">Code</span><span class="p" data-group-id="7775763822-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="7775763822-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="7775763822-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7775763822-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="7775763822-4">(</span><span class="n">Code</span><span class="p" data-group-id="7775763822-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7775763822-5">[</span><span class="p" data-group-id="7775763822-5">]</span><span class="p" data-group-id="7775763822-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7775763822-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7775763822-6">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1811957168-4">(</span><span class="p" data-group-id="1811957168-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1811957168-5">]</span><span class="p" data-group-id="1811957168-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1811957168-6">(</span><span class="p" data-group-id="1811957168-7">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1811957168-7">]</span><span class="p" data-group-id="1811957168-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1811957168-8">(</span><span class="p" data-group-id="1811957168-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="1811957168-9">]</span><span class="p" data-group-id="1811957168-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1811957168-10">(</span><span class="p" data-group-id="1811957168-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="1811957168-11">]</span><span class="p" data-group-id="1811957168-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="1811957168-12">(</span><span class="n">Code</span><span class="p" data-group-id="1811957168-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1811957168-13">(</span><span class="p" data-group-id="1811957168-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="1811957168-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1811957168-15">[</span><span class="p" data-group-id="1811957168-15">]</span><span class="p" data-group-id="1811957168-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="1811957168-16">(</span><span class="p" data-group-id="1811957168-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="1811957168-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="1811957168-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">down</span><span class="p" data-group-id="1811957168-18">(</span><span class="n">Button</span><span class="p" data-group-id="1811957168-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="1811957168-19">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1811957168-20">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1811957168-20">}</span><span class="p" data-group-id="1811957168-19">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">up</span><span class="p" data-group-id="1811957168-21">(</span><span class="n">Button</span><span class="p" data-group-id="1811957168-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="1811957168-22">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1811957168-23">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1811957168-23">}</span><span class="p" data-group-id="1811957168-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">code_length</span><span class="p" data-group-id="1811957168-24">(</span><span class="p" data-group-id="1811957168-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="1811957168-25">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="1811957168-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="9811385312-1">(</span><span class="n">Code</span><span class="p" data-group-id="9811385312-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="9811385312-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="9811385312-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9811385312-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="9811385312-4">(</span><span class="n">Code</span><span class="p" data-group-id="9811385312-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9811385312-5">[</span><span class="p" data-group-id="9811385312-5">]</span><span class="p" data-group-id="9811385312-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9811385312-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9811385312-6">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="7775763822-7">(</span><span class="p" data-group-id="7775763822-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7775763822-8">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="7775763822-8">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="9811385312-7">(</span><span class="p" data-group-id="9811385312-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9811385312-8">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="9811385312-8">]</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7775763822-9">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="7775763822-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="7775763822-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="7775763822-11">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="7775763822-11">)</span><span class="p" data-group-id="7775763822-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9811385312-9">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="9811385312-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="9811385312-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="9811385312-11">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="9811385312-11">)</span><span class="p" data-group-id="9811385312-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="7775763822-12">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7775763822-13">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7775763822-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7775763822-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7775763822-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7775763822-15">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="7775763822-15">}</span><span class="p" data-group-id="7775763822-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="7775763822-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7775763822-17">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7775763822-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7775763822-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="9811385312-12">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9811385312-13">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9811385312-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9811385312-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9811385312-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9811385312-15">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="9811385312-15">}</span><span class="p" data-group-id="9811385312-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="9811385312-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9811385312-17">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9811385312-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9811385312-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Data</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="7775763822-18">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="7775763822-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="7775763822-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="7775763822-20">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7775763822-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="7775763822-21">[</span><span class="p" data-group-id="7775763822-22">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="7775763822-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7775763822-23">}</span><span class="p" data-group-id="7775763822-22">}</span><span class="p" data-group-id="7775763822-21">]</span><span class="p" data-group-id="7775763822-19">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="7775763822-24">#{</span><span class="p" data-group-id="7775763822-24">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="9811385312-18">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="9811385312-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9811385312-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="9811385312-20">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9811385312-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="9811385312-21">[</span><span class="p" data-group-id="9811385312-22">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="9811385312-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9811385312-23">}</span><span class="p" data-group-id="9811385312-22">}</span><span class="p" data-group-id="9811385312-21">]</span><span class="p" data-group-id="9811385312-19">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="9811385312-24">#{</span><span class="p" data-group-id="9811385312-24">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="7775763822-25">(</span><span class="p" data-group-id="7775763822-26">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="7775763822-26">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7775763822-27">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="7775763822-27">}</span><span class="p" data-group-id="7775763822-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7775763822-28">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="7775763822-29">[</span><span class="p" data-group-id="7775763822-30">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="7775763822-31">(</span><span class="n">Code</span><span class="p" data-group-id="7775763822-31">)</span><span class="p" data-group-id="7775763822-30">}</span><span class="p" data-group-id="7775763822-29">]</span><span class="p" data-group-id="7775763822-28">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="0356328308-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0356328308-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="0356328308-2">(</span><span class="p" data-group-id="0356328308-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0356328308-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0356328308-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="0356328308-5">[</span><span class="p" data-group-id="0356328308-5">]</span><span class="p" data-group-id="0356328308-4">}</span><span class="p" data-group-id="0356328308-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="0356328308-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0356328308-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0356328308-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0356328308-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="0356328308-9">[</span><span class="p" data-group-id="0356328308-9">]</span><span class="p" data-group-id="0356328308-8">}</span><span class="p" data-group-id="0356328308-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="0356328308-10">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0356328308-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0356328308-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="0356328308-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="0356328308-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0356328308-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="9811385312-25">(</span><span class="p" data-group-id="9811385312-26">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="9811385312-26">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9811385312-27">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="9811385312-27">}</span><span class="p" data-group-id="9811385312-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9811385312-28">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="9811385312-29">[</span><span class="p" data-group-id="9811385312-30">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="9811385312-31">(</span><span class="n">Code</span><span class="p" data-group-id="9811385312-31">)</span><span class="p" data-group-id="9811385312-30">}</span><span class="p" data-group-id="9811385312-29">]</span><span class="p" data-group-id="9811385312-28">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="9287038389-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9287038389-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="9287038389-2">(</span><span class="p" data-group-id="9287038389-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9287038389-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9287038389-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9287038389-5">[</span><span class="p" data-group-id="9287038389-5">]</span><span class="p" data-group-id="9287038389-4">}</span><span class="p" data-group-id="9287038389-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="9287038389-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9287038389-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9287038389-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9287038389-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9287038389-9">[</span><span class="p" data-group-id="9287038389-9">]</span><span class="p" data-group-id="9287038389-8">}</span><span class="p" data-group-id="9287038389-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="9287038389-10">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9287038389-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9287038389-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9287038389-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="9287038389-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9287038389-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │          </span><span class="k">if</span><span class="w">
│ │ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="0356328308-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="0356328308-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="9287038389-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="9287038389-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="0356328308-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="0356328308-14">)</span><span class="w">
│ │ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="0356328308-15">[</span><span class="n">Button</span><span class="p" data-group-id="0356328308-15">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="9287038389-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="9287038389-14">)</span><span class="w">
│ │ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9287038389-15">[</span><span class="n">Button</span><span class="p" data-group-id="9287038389-15">]</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="0356328308-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0356328308-16">}</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9287038389-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9287038389-16">}</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="0356328308-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0356328308-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="0356328308-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="0356328308-19">[</span><span class="p" data-group-id="0356328308-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="0356328308-20">}</span><span class="p" data-group-id="0356328308-19">]</span><span class="p" data-group-id="0356328308-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9287038389-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9287038389-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="9287038389-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="9287038389-19">[</span><span class="p" data-group-id="9287038389-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="9287038389-20">}</span><span class="p" data-group-id="9287038389-19">]</span><span class="p" data-group-id="9287038389-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="6585871856-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="6585871856-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="6585871856-2">(</span><span class="p" data-group-id="6585871856-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6585871856-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="6585871856-4">[</span><span class="p" data-group-id="6585871856-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="6585871856-5">}</span><span class="p" data-group-id="6585871856-4">]</span><span class="p" data-group-id="6585871856-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="6585871856-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6585871856-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6585871856-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6585871856-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="6585871856-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6585871856-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6585871856-9">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6585871856-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6585871856-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6585871856-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="6585871856-11">]</span><span class="p" data-group-id="6585871856-10">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="1589048806-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="1589048806-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="1589048806-2">(</span><span class="p" data-group-id="1589048806-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1589048806-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="1589048806-4">[</span><span class="p" data-group-id="1589048806-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="1589048806-5">}</span><span class="p" data-group-id="1589048806-4">]</span><span class="p" data-group-id="1589048806-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1589048806-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1589048806-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1589048806-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1589048806-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1589048806-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1589048806-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="1589048806-9">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="1589048806-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1589048806-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1589048806-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="1589048806-11">]</span><span class="p" data-group-id="1589048806-10">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">do_lock</span><span class="p" data-group-id="6585871856-12">(</span><span class="p" data-group-id="6585871856-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6585871856-13">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6585871856-14">[</span><span class="p" data-group-id="6585871856-14">]</span><span class="p" data-group-id="6585871856-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="6585871856-15">(</span><span class="p" data-group-id="6585871856-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6585871856-16">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6585871856-17">[</span><span class="p" data-group-id="6585871856-17">]</span><span class="p" data-group-id="6585871856-16">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">do_lock</span><span class="p" data-group-id="1589048806-12">(</span><span class="p" data-group-id="1589048806-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1589048806-13">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1589048806-14">[</span><span class="p" data-group-id="1589048806-14">]</span><span class="p" data-group-id="1589048806-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="1589048806-15">(</span><span class="p" data-group-id="1589048806-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1589048806-16">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1589048806-17">[</span><span class="p" data-group-id="1589048806-17">]</span><span class="p" data-group-id="1589048806-16">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="6585871856-18">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="6585871856-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="6585871856-19">(</span><span class="p" data-group-id="6585871856-19">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="1589048806-18">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="1589048806-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="1589048806-19">(</span><span class="p" data-group-id="1589048806-19">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h3 id="callback-mode-handle_event_function" class="section-heading">
│ │ │ │    <a href="#callback-mode-handle_event_function" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Callback Mode: handle_event_function</span>
│ │ │ │  </h3>
│ │ │ │  <p>This section describes what to change in the example to use one
│ │ │ │  <code class="inline">handle_event/4</code> function.  The previously used approach to first branch
│ │ │ │  depending on event does not work that well here because of
│ │ │ │ -the <em>state enter calls</em>, so this example first branches depending on state:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2098826169-1">(</span><span class="p" data-group-id="2098826169-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="2098826169-2">]</span><span class="p" data-group-id="2098826169-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="5889055345-1">(</span><span class="p" data-group-id="5889055345-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5889055345-2">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="5889055345-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ │ +the <em>state enter calls</em>, so this example first branches depending on state:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8281807717-1">(</span><span class="p" data-group-id="8281807717-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="8281807717-2">]</span><span class="p" data-group-id="8281807717-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="6534699778-1">(</span><span class="p" data-group-id="6534699778-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6534699778-2">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="6534699778-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ │  </span><span class="c1">%% State: locked</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="6779487277-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6779487277-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="6779487277-2">(</span><span class="p" data-group-id="6779487277-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6779487277-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6779487277-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6779487277-5">[</span><span class="p" data-group-id="6779487277-5">]</span><span class="p" data-group-id="6779487277-4">}</span><span class="p" data-group-id="6779487277-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="6779487277-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6779487277-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6779487277-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6779487277-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6779487277-9">[</span><span class="p" data-group-id="6779487277-9">]</span><span class="p" data-group-id="6779487277-8">}</span><span class="p" data-group-id="6779487277-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="6779487277-10">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6779487277-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6779487277-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="6779487277-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="6779487277-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6779487277-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5299459794-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5299459794-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="5299459794-2">(</span><span class="p" data-group-id="5299459794-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5299459794-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5299459794-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="5299459794-5">[</span><span class="p" data-group-id="5299459794-5">]</span><span class="p" data-group-id="5299459794-4">}</span><span class="p" data-group-id="5299459794-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5299459794-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5299459794-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5299459794-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5299459794-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="5299459794-9">[</span><span class="p" data-group-id="5299459794-9">]</span><span class="p" data-group-id="5299459794-8">}</span><span class="p" data-group-id="5299459794-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5299459794-10">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5299459794-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5299459794-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="5299459794-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="5299459794-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5299459794-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │          </span><span class="k">if</span><span class="w">
│ │ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="6779487277-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="6779487277-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="5299459794-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="5299459794-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="6779487277-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="6779487277-14">)</span><span class="w">
│ │ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6779487277-15">[</span><span class="n">Button</span><span class="p" data-group-id="6779487277-15">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="5299459794-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="5299459794-14">)</span><span class="w">
│ │ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="5299459794-15">[</span><span class="n">Button</span><span class="p" data-group-id="5299459794-15">]</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6779487277-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6779487277-16">}</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="5299459794-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5299459794-16">}</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6779487277-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6779487277-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="6779487277-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="6779487277-19">[</span><span class="p" data-group-id="6779487277-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="6779487277-20">}</span><span class="p" data-group-id="6779487277-19">]</span><span class="p" data-group-id="6779487277-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="5299459794-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5299459794-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="5299459794-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="5299459794-19">[</span><span class="p" data-group-id="5299459794-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="5299459794-20">}</span><span class="p" data-group-id="5299459794-19">]</span><span class="p" data-group-id="5299459794-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ │  </span><span class="c1">%% State: open</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="7342424527-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="7342424527-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="7342424527-2">(</span><span class="p" data-group-id="7342424527-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7342424527-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="7342424527-4">[</span><span class="p" data-group-id="7342424527-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="7342424527-5">}</span><span class="p" data-group-id="7342424527-4">]</span><span class="p" data-group-id="7342424527-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="7342424527-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7342424527-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7342424527-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7342424527-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="7342424527-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7342424527-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7342424527-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7342424527-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7342424527-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="7342424527-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="7342424527-11">]</span><span class="p" data-group-id="7342424527-10">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%% Common events</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0408289234-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0408289234-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0408289234-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0408289234-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0408289234-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0408289234-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="0408289234-4">}</span><span class="p" data-group-id="0408289234-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0408289234-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0408289234-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0408289234-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0408289234-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="6225200399-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="6225200399-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="6225200399-2">(</span><span class="p" data-group-id="6225200399-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6225200399-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="6225200399-4">[</span><span class="p" data-group-id="6225200399-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="6225200399-5">}</span><span class="p" data-group-id="6225200399-4">]</span><span class="p" data-group-id="6225200399-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="6225200399-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6225200399-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6225200399-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6225200399-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="6225200399-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6225200399-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6225200399-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6225200399-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6225200399-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="6225200399-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="6225200399-11">]</span><span class="p" data-group-id="6225200399-10">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%% Common events</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="4484290568-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4484290568-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4484290568-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4484290568-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4484290568-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4484290568-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="4484290568-4">}</span><span class="p" data-group-id="4484290568-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="4484290568-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4484290568-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4484290568-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4484290568-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Data</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0408289234-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="0408289234-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="0408289234-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="0408289234-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0408289234-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="0408289234-10">[</span><span class="p" data-group-id="0408289234-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="0408289234-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0408289234-12">}</span><span class="p" data-group-id="0408289234-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="0408289234-13">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="0408289234-13">}</span><span class="p" data-group-id="0408289234-10">]</span><span class="p" data-group-id="0408289234-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0408289234-14">#{</span><span class="p" data-group-id="0408289234-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="4484290568-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="4484290568-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="4484290568-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="4484290568-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4484290568-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="4484290568-10">[</span><span class="p" data-group-id="4484290568-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="4484290568-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4484290568-12">}</span><span class="p" data-group-id="4484290568-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="4484290568-13">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="4484290568-13">}</span><span class="p" data-group-id="4484290568-10">]</span><span class="p" data-group-id="4484290568-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="4484290568-14">#{</span><span class="p" data-group-id="4484290568-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0408289234-15">(</span><span class="p" data-group-id="0408289234-16">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="0408289234-16">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0408289234-17">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="0408289234-17">}</span><span class="p" data-group-id="0408289234-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0408289234-18">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="0408289234-19">[</span><span class="p" data-group-id="0408289234-20">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">Length</span><span class="p" data-group-id="0408289234-20">}</span><span class="p" data-group-id="0408289234-19">]</span><span class="p" data-group-id="0408289234-18">}</span><span class="p">.</span></code></pre><p>Notice that postponing buttons from the <code class="inline">open</code> state to the <code class="inline">locked</code> state
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="4484290568-15">(</span><span class="p" data-group-id="4484290568-16">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="4484290568-16">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4484290568-17">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="4484290568-17">}</span><span class="p" data-group-id="4484290568-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4484290568-18">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="4484290568-19">[</span><span class="p" data-group-id="4484290568-20">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">Length</span><span class="p" data-group-id="4484290568-20">}</span><span class="p" data-group-id="4484290568-19">]</span><span class="p" data-group-id="4484290568-18">}</span><span class="p">.</span></code></pre><p>Notice that postponing buttons from the <code class="inline">open</code> state to the <code class="inline">locked</code> state
│ │ │ │  seems like a strange thing to do for a code lock, but it at least
│ │ │ │  illustrates event postponing.</p><h2 id="filter-the-state" class="section-heading">
│ │ │ │    <a href="#filter-the-state" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Filter the State</span>
│ │ │ │  </h2>
│ │ │ │ @@ -1191,30 +1191,30 @@
│ │ │ │  and which digits that remain to unlock.</p><p>This state data can be regarded as sensitive, and maybe not what you want
│ │ │ │  in the error log because of some unpredictable event.</p><p>Another reason to filter the state can be that the state is too large to print,
│ │ │ │  as it fills the error log with uninteresting details.</p><p>To avoid this, you can format the internal state that gets in the error log
│ │ │ │  and gets returned from <a href="../../../lib/stdlib/doc/html/sys.html#get_status/1"><code class="inline">sys:get_status/1,2</code></a>
│ │ │ │  by implementing function
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#c:format_status/2"><code class="inline">Module:format_status/2</code></a>,
│ │ │ │  for example like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0267738983-1">(</span><span class="p" data-group-id="0267738983-2">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">format_status</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0267738983-2">]</span><span class="p" data-group-id="0267738983-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7312739234-1">(</span><span class="p" data-group-id="7312739234-2">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">format_status</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7312739234-2">]</span><span class="p" data-group-id="7312739234-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">format_status</span><span class="p" data-group-id="0267738983-3">(</span><span class="n">Opt</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0267738983-4">[</span><span class="p">_</span><span class="n">PDict</span><span class="p">,</span><span class="n">State</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="0267738983-4">]</span><span class="p" data-group-id="0267738983-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">format_status</span><span class="p" data-group-id="7312739234-3">(</span><span class="n">Opt</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7312739234-4">[</span><span class="p">_</span><span class="n">PDict</span><span class="p">,</span><span class="n">State</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="7312739234-4">]</span><span class="p" data-group-id="7312739234-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">StateData</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="0267738983-5">{</span><span class="n">State</span><span class="p">,</span><span class="w">
│ │ │ │ -	 </span><span class="nc">maps</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="0267738983-6">(</span><span class="w">
│ │ │ │ -	   </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="0267738983-7">(</span><span class="ss">code</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="0267738983-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="p">;</span><span class="w">
│ │ │ │ -	       </span><span class="p" data-group-id="0267738983-8">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="0267738983-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="7312739234-5">{</span><span class="n">State</span><span class="p">,</span><span class="w">
│ │ │ │ +	 </span><span class="nc">maps</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="7312739234-6">(</span><span class="w">
│ │ │ │ +	   </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="7312739234-7">(</span><span class="ss">code</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7312739234-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="p">;</span><span class="w">
│ │ │ │ +	       </span><span class="p" data-group-id="7312739234-8">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7312739234-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="w">
│ │ │ │  	   </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -	   </span><span class="n">Data</span><span class="p" data-group-id="0267738983-6">)</span><span class="p" data-group-id="0267738983-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	   </span><span class="n">Data</span><span class="p" data-group-id="7312739234-6">)</span><span class="p" data-group-id="7312739234-5">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Opt</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │  	</span><span class="ss">terminate</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  	    </span><span class="n">StateData</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">normal</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="p" data-group-id="0267738983-9">[</span><span class="p" data-group-id="0267738983-10">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="0267738983-11">[</span><span class="p" data-group-id="0267738983-12">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="n">StateData</span><span class="p" data-group-id="0267738983-12">}</span><span class="p" data-group-id="0267738983-11">]</span><span class="p" data-group-id="0267738983-10">}</span><span class="p" data-group-id="0267738983-9">]</span><span class="w">
│ │ │ │ +	    </span><span class="p" data-group-id="7312739234-9">[</span><span class="p" data-group-id="7312739234-10">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="7312739234-11">[</span><span class="p" data-group-id="7312739234-12">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="n">StateData</span><span class="p" data-group-id="7312739234-12">}</span><span class="p" data-group-id="7312739234-11">]</span><span class="p" data-group-id="7312739234-10">}</span><span class="p" data-group-id="7312739234-9">]</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>It is not mandatory to implement a
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_statem.html#c:format_status/2"><code class="inline">Module:format_status/2</code></a> function.
│ │ │ │  If you do not, a default implementation is used that does the same
│ │ │ │  as this example function without filtering the <code class="inline">Data</code> term, that is,
│ │ │ │  <code class="inline">StateData = {State, Data}</code>, in this example containing sensitive information.</p><h2 id="complex-state" class="section-heading">
│ │ │ │    <a href="#complex-state" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │ @@ -1227,104 +1227,104 @@
│ │ │ │  like a tuple.</p><p>One reason to use this is when you have a state item that when changed
│ │ │ │  should cancel the <a href="#state-time-outs"><em>state time-out</em></a>, or one that affects
│ │ │ │  the event handling in combination with postponing events. We will go for
│ │ │ │  the latter and complicate the previous example by introducing
│ │ │ │  a configurable lock button (this is the state item in question),
│ │ │ │  which in the <code class="inline">open</code> state immediately locks the door, and an API function
│ │ │ │  <code class="inline">set_lock_button/1</code> to set the lock button.</p><p>Suppose now that we call <code class="inline">set_lock_button</code> while the door is open,
│ │ │ │ -and we have already postponed a button event that was the new lock button:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8107643639-1">(</span><span class="p" data-group-id="8107643639-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8107643639-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">x</span><span class="p" data-group-id="8107643639-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8107643639-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.666</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="8107643639-3">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="8107643639-4">(</span><span class="ss">a</span><span class="p" data-group-id="8107643639-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +and we have already postponed a button event that was the new lock button:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="7288246031-1">(</span><span class="p" data-group-id="7288246031-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7288246031-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">x</span><span class="p" data-group-id="7288246031-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7288246031-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.666</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="7288246031-3">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="7288246031-4">(</span><span class="ss">a</span><span class="p" data-group-id="7288246031-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="8107643639-5">(</span><span class="ss">b</span><span class="p" data-group-id="8107643639-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="7288246031-5">(</span><span class="ss">b</span><span class="p" data-group-id="7288246031-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="8107643639-6">(</span><span class="ss">c</span><span class="p" data-group-id="8107643639-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="7288246031-6">(</span><span class="ss">c</span><span class="p" data-group-id="7288246031-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="n">Open</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="8107643639-7">(</span><span class="ss">y</span><span class="p" data-group-id="8107643639-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="7288246031-7">(</span><span class="ss">y</span><span class="p" data-group-id="7288246031-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">set_lock_button</span><span class="p" data-group-id="8107643639-8">(</span><span class="ss">y</span><span class="p" data-group-id="8107643639-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">set_lock_button</span><span class="p" data-group-id="7288246031-8">(</span><span class="ss">y</span><span class="p" data-group-id="7288246031-8">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">x</span><span class="w">
│ │ │ │  </span><span class="c1">% What should happen here?  Immediate lock or nothing?</span></code></pre><p>We could say that the button was pressed too early so it should not be
│ │ │ │  recognized as the lock button. Or we can make the lock button part of
│ │ │ │  the state so when we then change the lock button in the locked state,
│ │ │ │  the change becomes a <em>state change</em> and all postponed events are retried,
│ │ │ │  therefore the lock is immediately locked!</p><p>We define the state as <code class="inline">{StateName, LockButton}</code>, where <code class="inline">StateName</code>
│ │ │ │ -is as before and <code class="inline">LockButton</code> is the current lock button:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5327705239-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="5327705239-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5327705239-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="5327705239-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5327705239-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_3</span><span class="p" data-group-id="5327705239-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +is as before and <code class="inline">LockButton</code> is the current lock button:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1235952167-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="1235952167-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="1235952167-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="1235952167-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1235952167-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_3</span><span class="p" data-group-id="1235952167-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5327705239-4">(</span><span class="p" data-group-id="5327705239-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5327705239-5">]</span><span class="p" data-group-id="5327705239-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5327705239-6">(</span><span class="p" data-group-id="5327705239-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">set_lock_button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5327705239-7">]</span><span class="p" data-group-id="5327705239-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5327705239-8">(</span><span class="p" data-group-id="5327705239-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5327705239-9">]</span><span class="p" data-group-id="5327705239-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5327705239-10">(</span><span class="p" data-group-id="5327705239-11">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="5327705239-11">]</span><span class="p" data-group-id="5327705239-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="5327705239-12">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">LockButton</span><span class="p" data-group-id="5327705239-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5327705239-13">(</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="5327705239-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="5327705239-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5327705239-15">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5327705239-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5327705239-16">[</span><span class="p" data-group-id="5327705239-16">]</span><span class="p" data-group-id="5327705239-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="5327705239-17">(</span><span class="p" data-group-id="5327705239-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="5327705239-18">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="5327705239-18">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">button</span><span class="p" data-group-id="5327705239-19">(</span><span class="n">Button</span><span class="p" data-group-id="5327705239-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="5327705239-20">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5327705239-21">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5327705239-21">}</span><span class="p" data-group-id="5327705239-20">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">set_lock_button</span><span class="p" data-group-id="5327705239-22">(</span><span class="n">LockButton</span><span class="p" data-group-id="5327705239-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="5327705239-23">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5327705239-24">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5327705239-24">}</span><span class="p" data-group-id="5327705239-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="4017059172-1">(</span><span class="p" data-group-id="4017059172-2">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4017059172-2">}</span><span class="p" data-group-id="4017059172-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="4017059172-3">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="4017059172-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4017059172-4">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="4017059172-5">(</span><span class="n">Code</span><span class="p" data-group-id="4017059172-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4017059172-6">[</span><span class="p" data-group-id="4017059172-6">]</span><span class="p" data-group-id="4017059172-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4017059172-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4017059172-8">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4017059172-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-7">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1235952167-4">(</span><span class="p" data-group-id="1235952167-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1235952167-5">]</span><span class="p" data-group-id="1235952167-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1235952167-6">(</span><span class="p" data-group-id="1235952167-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">set_lock_button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1235952167-7">]</span><span class="p" data-group-id="1235952167-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1235952167-8">(</span><span class="p" data-group-id="1235952167-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="1235952167-9">]</span><span class="p" data-group-id="1235952167-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1235952167-10">(</span><span class="p" data-group-id="1235952167-11">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="1235952167-11">]</span><span class="p" data-group-id="1235952167-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="1235952167-12">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">LockButton</span><span class="p" data-group-id="1235952167-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1235952167-13">(</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="1235952167-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="1235952167-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1235952167-15">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="1235952167-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1235952167-16">[</span><span class="p" data-group-id="1235952167-16">]</span><span class="p" data-group-id="1235952167-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="1235952167-17">(</span><span class="p" data-group-id="1235952167-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="1235952167-18">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="1235952167-18">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">button</span><span class="p" data-group-id="1235952167-19">(</span><span class="n">Button</span><span class="p" data-group-id="1235952167-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="1235952167-20">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1235952167-21">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1235952167-21">}</span><span class="p" data-group-id="1235952167-20">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">set_lock_button</span><span class="p" data-group-id="1235952167-22">(</span><span class="n">LockButton</span><span class="p" data-group-id="1235952167-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="1235952167-23">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1235952167-24">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="1235952167-24">}</span><span class="p" data-group-id="1235952167-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="8110617176-1">(</span><span class="p" data-group-id="8110617176-2">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="8110617176-2">}</span><span class="p" data-group-id="8110617176-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="8110617176-3">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8110617176-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8110617176-4">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="8110617176-5">(</span><span class="n">Code</span><span class="p" data-group-id="8110617176-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8110617176-6">[</span><span class="p" data-group-id="8110617176-6">]</span><span class="p" data-group-id="8110617176-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8110617176-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8110617176-8">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="8110617176-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-7">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="4017059172-9">(</span><span class="p" data-group-id="4017059172-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4017059172-10">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="4017059172-10">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="8110617176-9">(</span><span class="p" data-group-id="8110617176-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8110617176-10">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="8110617176-10">]</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% State: locked</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4017059172-11">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4017059172-12">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4017059172-12">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="4017059172-13">(</span><span class="p" data-group-id="4017059172-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4017059172-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-15">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="4017059172-16">[</span><span class="p" data-group-id="4017059172-16">]</span><span class="p" data-group-id="4017059172-15">}</span><span class="p" data-group-id="4017059172-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4017059172-17">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4017059172-18">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4017059172-18">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4017059172-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-20">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="4017059172-21">[</span><span class="p" data-group-id="4017059172-21">]</span><span class="p" data-group-id="4017059172-20">}</span><span class="p" data-group-id="4017059172-19">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4017059172-22">(</span><span class="w">
│ │ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4017059172-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4017059172-23">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4017059172-24">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4017059172-24">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4017059172-25">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="4017059172-25">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="8110617176-11">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8110617176-12">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8110617176-12">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="8110617176-13">(</span><span class="p" data-group-id="8110617176-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8110617176-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-15">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="8110617176-16">[</span><span class="p" data-group-id="8110617176-16">]</span><span class="p" data-group-id="8110617176-15">}</span><span class="p" data-group-id="8110617176-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="8110617176-17">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8110617176-18">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8110617176-18">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8110617176-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-20">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="8110617176-21">[</span><span class="p" data-group-id="8110617176-21">]</span><span class="p" data-group-id="8110617176-20">}</span><span class="p" data-group-id="8110617176-19">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="8110617176-22">(</span><span class="w">
│ │ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8110617176-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8110617176-23">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8110617176-24">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="8110617176-24">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8110617176-25">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="8110617176-25">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │          </span><span class="k">if</span><span class="w">
│ │ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="4017059172-26">(</span><span class="n">Buttons</span><span class="p" data-group-id="4017059172-26">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="8110617176-26">(</span><span class="n">Buttons</span><span class="p" data-group-id="8110617176-26">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="4017059172-27">(</span><span class="n">Buttons</span><span class="p" data-group-id="4017059172-27">)</span><span class="w">
│ │ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="4017059172-28">[</span><span class="n">Button</span><span class="p" data-group-id="4017059172-28">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="8110617176-27">(</span><span class="n">Buttons</span><span class="p" data-group-id="8110617176-27">)</span><span class="w">
│ │ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="8110617176-28">[</span><span class="n">Button</span><span class="p" data-group-id="8110617176-28">]</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="4017059172-29">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4017059172-30">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4017059172-30">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-29">}</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="8110617176-29">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8110617176-30">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="8110617176-30">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-29">}</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="4017059172-31">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4017059172-32">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="4017059172-32">}</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="4017059172-33">[</span><span class="p" data-group-id="4017059172-34">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="4017059172-34">}</span><span class="p" data-group-id="4017059172-33">]</span><span class="p" data-group-id="4017059172-31">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="8110617176-31">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8110617176-32">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="8110617176-32">}</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="8110617176-33">[</span><span class="p" data-group-id="8110617176-34">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="8110617176-34">}</span><span class="p" data-group-id="8110617176-33">]</span><span class="p" data-group-id="8110617176-31">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ │  </span><span class="c1">%% State: open</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4183572831-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4183572831-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="4183572831-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="4183572831-3">(</span><span class="p" data-group-id="4183572831-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4183572831-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="4183572831-5">[</span><span class="p" data-group-id="4183572831-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="4183572831-6">}</span><span class="p" data-group-id="4183572831-5">]</span><span class="p" data-group-id="4183572831-4">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4183572831-7">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-8">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4183572831-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4183572831-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4183572831-9">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-10">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4183572831-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4183572831-9">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4183572831-11">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4183572831-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-13">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4183572831-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4183572831-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4183572831-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-15">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="4183572831-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4183572831-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4183572831-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4183572831-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4183572831-18">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4183572831-18">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="4183572831-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4183572831-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="4183572831-20">[</span><span class="ss">postpone</span><span class="p" data-group-id="4183572831-20">]</span><span class="p" data-group-id="4183572831-19">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5066381208-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5066381208-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="5066381208-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="5066381208-3">(</span><span class="p" data-group-id="5066381208-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5066381208-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="5066381208-5">[</span><span class="p" data-group-id="5066381208-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="5066381208-6">}</span><span class="p" data-group-id="5066381208-5">]</span><span class="p" data-group-id="5066381208-4">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5066381208-7">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-8">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5066381208-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5066381208-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5066381208-9">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-10">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5066381208-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5066381208-9">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5066381208-11">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5066381208-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-13">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5066381208-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5066381208-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5066381208-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-15">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5066381208-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5066381208-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5066381208-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5066381208-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5066381208-18">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5066381208-18">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="5066381208-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5066381208-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="5066381208-20">[</span><span class="ss">postpone</span><span class="p" data-group-id="5066381208-20">]</span><span class="p" data-group-id="5066381208-19">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ │  </span><span class="c1">%% Common events</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="3489713087-1">(</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="3489713087-2">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="3489713087-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3489713087-3">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="3489713087-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="3489713087-4">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="3489713087-4">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3489713087-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3489713087-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3489713087-6">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="3489713087-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="3489713087-7">[</span><span class="p" data-group-id="3489713087-8">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="3489713087-8">}</span><span class="p" data-group-id="3489713087-7">]</span><span class="p" data-group-id="3489713087-5">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="9715239519-1">(</span><span class="p" data-group-id="9715239519-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9715239519-2">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9715239519-3">[</span><span class="p" data-group-id="9715239519-3">]</span><span class="p" data-group-id="9715239519-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="9715239519-4">(</span><span class="p" data-group-id="9715239519-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9715239519-5">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9715239519-6">[</span><span class="p" data-group-id="9715239519-6">]</span><span class="p" data-group-id="9715239519-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="7164399580-1">(</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7164399580-2">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="7164399580-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7164399580-3">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="7164399580-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7164399580-4">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="7164399580-4">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7164399580-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7164399580-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7164399580-6">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="7164399580-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="7164399580-7">[</span><span class="p" data-group-id="7164399580-8">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="7164399580-8">}</span><span class="p" data-group-id="7164399580-7">]</span><span class="p" data-group-id="7164399580-5">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="5435229057-1">(</span><span class="p" data-group-id="5435229057-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5435229057-2">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5435229057-3">[</span><span class="p" data-group-id="5435229057-3">]</span><span class="p" data-group-id="5435229057-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="5435229057-4">(</span><span class="p" data-group-id="5435229057-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5435229057-5">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5435229057-6">[</span><span class="p" data-group-id="5435229057-6">]</span><span class="p" data-group-id="5435229057-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="9715239519-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="9715239519-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="9715239519-8">(</span><span class="p" data-group-id="9715239519-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="5435229057-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="5435229057-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="5435229057-8">(</span><span class="p" data-group-id="5435229057-8">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h2 id="hibernation" class="section-heading">
│ │ │ │    <a href="#hibernation" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Hibernation</span>
│ │ │ │  </h2>
│ │ │ │  <p>If you have many servers in one node and they have some state(s) in their
│ │ │ │ @@ -1333,19 +1333,19 @@
│ │ │ │  footprint of a server can be minimized by hibernating it through
│ │ │ │  <a href="../../../lib/stdlib/doc/html/proc_lib.html#hibernate/3"><code class="inline">proc_lib:hibernate/3</code></a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>It is rather costly to hibernate a process; see <a href="../../../lib/../erts/doc/html/erlang.html#hibernate/3"><code class="inline">erlang:hibernate/3</code></a>. It is
│ │ │ │  not something you want to do after every event.</p></section><p>We can in this example hibernate in the <code class="inline">{open, _}</code> state,
│ │ │ │  because what normally occurs in that state is that the <em>state time-out</em>
│ │ │ │  after a while triggers a transition to <code class="inline">{locked, _}</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │  </span><span class="c1">%% State: open</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0736390894-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0736390894-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0736390894-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="0736390894-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="0736390894-3">(</span><span class="p" data-group-id="0736390894-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0736390894-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="0736390894-5">[</span><span class="p" data-group-id="0736390894-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="0736390894-6">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ -      </span><span class="ss">hibernate</span><span class="p" data-group-id="0736390894-5">]</span><span class="p" data-group-id="0736390894-4">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="7959970068-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7959970068-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7959970068-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="7959970068-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="7959970068-3">(</span><span class="p" data-group-id="7959970068-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7959970068-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="7959970068-5">[</span><span class="p" data-group-id="7959970068-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="7959970068-6">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ │ +      </span><span class="ss">hibernate</span><span class="p" data-group-id="7959970068-5">]</span><span class="p" data-group-id="7959970068-4">}</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The atom <a href="../../../lib/stdlib/doc/html/gen_statem.html#t:hibernate/0"><code class="inline">hibernate</code></a> in the action list on the
│ │ │ │  last line when entering the <code class="inline">{open, _}</code> state is the only change. If any event
│ │ │ │  arrives in the <code class="inline">{open, _},</code> state, we do not bother to rehibernate,
│ │ │ │  so the server stays awake after any event.</p><p>To change that we would need to insert action <code class="inline">hibernate</code> in more places.
│ │ │ │  For example, the state-independent <code class="inline">set_lock_button</code> operation
│ │ │ │  would have to use <code class="inline">hibernate</code> but only in the <code class="inline">{open, _}</code> state,
│ │ │ │  which would clutter the code.</p><p>Another not uncommon scenario is to use the
│ │ │ ├── OEBPS/spec_proc.xhtml
│ │ │ │ @@ -28,72 +28,72 @@
│ │ │ │    <a href="#simple-debugging" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Simple Debugging</span>
│ │ │ │  </h2>
│ │ │ │  <p>The <a href="../../../lib/stdlib/doc/html/sys.html"><code class="inline">sys</code></a> module has functions for simple debugging of processes implemented
│ │ │ │  using behaviours. The <code class="inline">code_lock</code> example from
│ │ │ │ -<a href="statem.xhtml#example">gen_statem Behaviour</a> is used to illustrate this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="5631743628-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="5631743628-1">]</span><span class="w"> </span><span class="p" data-group-id="5631743628-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="5631743628-2">]</span><span class="w"> </span><span class="p" data-group-id="5631743628-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="5631743628-3">]</span><span class="w"> </span><span class="p" data-group-id="5631743628-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="5631743628-4">]</span><span class="w"> </span><span class="p" data-group-id="5631743628-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="5631743628-5">]</span><span class="w"> </span><span class="p" data-group-id="5631743628-6">[</span><span class="ss">jit</span><span class="p" data-group-id="5631743628-6">]</span><span class="w">
│ │ │ │ +<a href="statem.xhtml#example">gen_statem Behaviour</a> is used to illustrate this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="3747922763-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="3747922763-1">]</span><span class="w"> </span><span class="p" data-group-id="3747922763-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="3747922763-2">]</span><span class="w"> </span><span class="p" data-group-id="3747922763-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3747922763-3">]</span><span class="w"> </span><span class="p" data-group-id="3747922763-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="3747922763-4">]</span><span class="w"> </span><span class="p" data-group-id="3747922763-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3747922763-5">]</span><span class="w"> </span><span class="p" data-group-id="3747922763-6">[</span><span class="ss">jit</span><span class="p" data-group-id="3747922763-6">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="5631743628-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="5631743628-8">(</span><span class="p" data-group-id="5631743628-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="5631743628-7">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5631743628-9">(</span><span class="p" data-group-id="5631743628-10">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5631743628-10">]</span><span class="p" data-group-id="5631743628-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="3747922763-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="3747922763-8">(</span><span class="p" data-group-id="3747922763-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="3747922763-7">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3747922763-9">(</span><span class="p" data-group-id="3747922763-10">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3747922763-10">]</span><span class="p" data-group-id="3747922763-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="n">Lock</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5631743628-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5631743628-11">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="5631743628-12">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5631743628-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3747922763-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3747922763-11">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="3747922763-12">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3747922763-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="5631743628-13">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5631743628-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="3747922763-13">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3747922763-13">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="5631743628-14">(</span><span class="mi">1</span><span class="p" data-group-id="5631743628-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-15">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5631743628-15">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="3747922763-14">(</span><span class="mi">1</span><span class="p" data-group-id="3747922763-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-15">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3747922763-15">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-16">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5631743628-16">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="5631743628-17">(</span><span class="mi">2</span><span class="p" data-group-id="5631743628-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-18">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5631743628-18">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-16">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3747922763-16">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ │ +5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="3747922763-17">(</span><span class="mi">2</span><span class="p" data-group-id="3747922763-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-18">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3747922763-18">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-19">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5631743628-19">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="5631743628-20">(</span><span class="mi">3</span><span class="p" data-group-id="5631743628-20">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-21">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5631743628-21">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-19">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3747922763-19">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ │ +6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="3747922763-20">(</span><span class="mi">3</span><span class="p" data-group-id="3747922763-20">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-21">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3747922763-21">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-22">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5631743628-22">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ │ -7&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="5631743628-23">(</span><span class="mi">4</span><span class="p" data-group-id="5631743628-23">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-24">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5631743628-24">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-22">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3747922763-22">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ │ +7&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="3747922763-23">(</span><span class="mi">4</span><span class="p" data-group-id="3747922763-23">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-24">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3747922763-24">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="n">Unlock</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="5631743628-25">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5631743628-25">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="nb">start_timer</span><span class="w"> </span><span class="p" data-group-id="5631743628-26">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10000</span><span class="p">,</span><span class="ss">lock</span><span class="p">,</span><span class="p" data-group-id="5631743628-27">[</span><span class="p" data-group-id="5631743628-27">]</span><span class="p" data-group-id="5631743628-26">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="3747922763-25">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3747922763-25">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="nb">start_timer</span><span class="w"> </span><span class="p" data-group-id="3747922763-26">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10000</span><span class="p">,</span><span class="ss">lock</span><span class="p">,</span><span class="p" data-group-id="3747922763-27">[</span><span class="p" data-group-id="3747922763-27">]</span><span class="p" data-group-id="3747922763-26">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ │  </span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">state_timeout</span><span class="w"> </span><span class="ss">lock</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ │  </span><span class="n">Lock</span><span class="w">
│ │ │ │  </span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">state_timeout</span><span class="w"> </span><span class="ss">lock</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ │ -8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="5631743628-28">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="5631743628-28">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5631743628-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="5631743628-30">[</span><span class="p" data-group-id="5631743628-31">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="5631743628-32">{</span><span class="p" data-group-id="5631743628-33">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5631743628-33">}</span><span class="p">,</span><span class="p" data-group-id="5631743628-34">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5631743628-34">}</span><span class="p" data-group-id="5631743628-32">}</span><span class="p" data-group-id="5631743628-31">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="5631743628-35">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="5631743628-36">{</span><span class="p" data-group-id="5631743628-37">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5631743628-37">}</span><span class="p">,</span><span class="p" data-group-id="5631743628-38">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">48</span><span class="p" data-group-id="5631743628-38">}</span><span class="p" data-group-id="5631743628-36">}</span><span class="p" data-group-id="5631743628-35">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="5631743628-39">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">4098</span><span class="p" data-group-id="5631743628-39">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="5631743628-40">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5631743628-40">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="5631743628-41">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="5631743628-41">}</span><span class="p" data-group-id="5631743628-30">]</span><span class="p" data-group-id="5631743628-29">}</span><span class="gp unselectable">
│ │ │ │ -9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="5631743628-42">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="5631743628-42">)</span><span class="p">.</span><span class="w">
│ │ │ │ +8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="3747922763-28">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="3747922763-28">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3747922763-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3747922763-30">[</span><span class="p" data-group-id="3747922763-31">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="3747922763-32">{</span><span class="p" data-group-id="3747922763-33">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3747922763-33">}</span><span class="p">,</span><span class="p" data-group-id="3747922763-34">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3747922763-34">}</span><span class="p" data-group-id="3747922763-32">}</span><span class="p" data-group-id="3747922763-31">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="3747922763-35">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="3747922763-36">{</span><span class="p" data-group-id="3747922763-37">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3747922763-37">}</span><span class="p">,</span><span class="p" data-group-id="3747922763-38">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">48</span><span class="p" data-group-id="3747922763-38">}</span><span class="p" data-group-id="3747922763-36">}</span><span class="p" data-group-id="3747922763-35">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="3747922763-39">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">4098</span><span class="p" data-group-id="3747922763-39">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="3747922763-40">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3747922763-40">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="3747922763-41">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="3747922763-41">}</span><span class="p" data-group-id="3747922763-30">]</span><span class="p" data-group-id="3747922763-29">}</span><span class="gp unselectable">
│ │ │ │ +9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="3747922763-42">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="3747922763-42">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -10&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="5631743628-43">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="5631743628-43">)</span><span class="p">.</span><span class="w">
│ │ │ │ +10&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="3747922763-43">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="3747922763-43">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -11&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="5631743628-44">(</span><span class="ss">code_lock</span><span class="p" data-group-id="5631743628-44">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5631743628-45">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="5631743628-46">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">gen_statem</span><span class="p" data-group-id="5631743628-46">}</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="5631743628-47">[</span><span class="p" data-group-id="5631743628-48">[</span><span class="p" data-group-id="5631743628-49">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="5631743628-50">{</span><span class="ss">code_lock</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5631743628-50">}</span><span class="p" data-group-id="5631743628-49">}</span><span class="p">,</span><span class="w">
│ │ │ │ -          </span><span class="p" data-group-id="5631743628-51">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="5631743628-52">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ -                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5631743628-52">]</span><span class="p" data-group-id="5631743628-51">}</span><span class="p" data-group-id="5631743628-48">]</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="5631743628-53">[</span><span class="p" data-group-id="5631743628-53">]</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="5631743628-54">[</span><span class="p" data-group-id="5631743628-55">{</span><span class="ss">header</span><span class="p">,</span><span class="s">&quot;Status for state machine code_lock&quot;</span><span class="p" data-group-id="5631743628-55">}</span><span class="p">,</span><span class="w">
│ │ │ │ -          </span><span class="p" data-group-id="5631743628-56">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="5631743628-57">[</span><span class="p" data-group-id="5631743628-58">{</span><span class="s">&quot;Status&quot;</span><span class="p">,</span><span class="ss">running</span><span class="p" data-group-id="5631743628-58">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                 </span><span class="p" data-group-id="5631743628-59">{</span><span class="s">&quot;Parent&quot;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5631743628-59">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                 </span><span class="p" data-group-id="5631743628-60">{</span><span class="s">&quot;Modules&quot;</span><span class="p">,</span><span class="p" data-group-id="5631743628-61">[</span><span class="ss">code_lock</span><span class="p" data-group-id="5631743628-61">]</span><span class="p" data-group-id="5631743628-60">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                 </span><span class="p" data-group-id="5631743628-62">{</span><span class="s">&quot;Time-outs&quot;</span><span class="p">,</span><span class="p" data-group-id="5631743628-63">{</span><span class="mi">0</span><span class="p">,</span><span class="p" data-group-id="5631743628-64">[</span><span class="p" data-group-id="5631743628-64">]</span><span class="p" data-group-id="5631743628-63">}</span><span class="p" data-group-id="5631743628-62">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                 </span><span class="p" data-group-id="5631743628-65">{</span><span class="s">&quot;Logged Events&quot;</span><span class="p">,</span><span class="p" data-group-id="5631743628-66">[</span><span class="p" data-group-id="5631743628-66">]</span><span class="p" data-group-id="5631743628-65">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                 </span><span class="p" data-group-id="5631743628-67">{</span><span class="s">&quot;Postponed&quot;</span><span class="p">,</span><span class="p" data-group-id="5631743628-68">[</span><span class="p" data-group-id="5631743628-68">]</span><span class="p" data-group-id="5631743628-67">}</span><span class="p" data-group-id="5631743628-57">]</span><span class="p" data-group-id="5631743628-56">}</span><span class="p">,</span><span class="w">
│ │ │ │ -          </span><span class="p" data-group-id="5631743628-69">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="5631743628-70">[</span><span class="p" data-group-id="5631743628-71">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -                  </span><span class="p" data-group-id="5631743628-72">{</span><span class="ss">locked</span><span class="p">,</span><span class="p" data-group-id="5631743628-73">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5631743628-74">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5631743628-74">]</span><span class="p">,</span><span class="w">
│ │ │ │ -                            </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5631743628-75">[</span><span class="p" data-group-id="5631743628-75">]</span><span class="p" data-group-id="5631743628-73">}</span><span class="p" data-group-id="5631743628-72">}</span><span class="p" data-group-id="5631743628-71">}</span><span class="p" data-group-id="5631743628-70">]</span><span class="p" data-group-id="5631743628-69">}</span><span class="p" data-group-id="5631743628-54">]</span><span class="p" data-group-id="5631743628-47">]</span><span class="p" data-group-id="5631743628-45">}</span></code></pre><h2 id="special-processes" class="section-heading">
│ │ │ │ +11&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="3747922763-44">(</span><span class="ss">code_lock</span><span class="p" data-group-id="3747922763-44">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3747922763-45">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="3747922763-46">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">gen_statem</span><span class="p" data-group-id="3747922763-46">}</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="3747922763-47">[</span><span class="p" data-group-id="3747922763-48">[</span><span class="p" data-group-id="3747922763-49">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="3747922763-50">{</span><span class="ss">code_lock</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3747922763-50">}</span><span class="p" data-group-id="3747922763-49">}</span><span class="p">,</span><span class="w">
│ │ │ │ +          </span><span class="p" data-group-id="3747922763-51">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="3747922763-52">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ +                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3747922763-52">]</span><span class="p" data-group-id="3747922763-51">}</span><span class="p" data-group-id="3747922763-48">]</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="3747922763-53">[</span><span class="p" data-group-id="3747922763-53">]</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="3747922763-54">[</span><span class="p" data-group-id="3747922763-55">{</span><span class="ss">header</span><span class="p">,</span><span class="s">&quot;Status for state machine code_lock&quot;</span><span class="p" data-group-id="3747922763-55">}</span><span class="p">,</span><span class="w">
│ │ │ │ +          </span><span class="p" data-group-id="3747922763-56">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="3747922763-57">[</span><span class="p" data-group-id="3747922763-58">{</span><span class="s">&quot;Status&quot;</span><span class="p">,</span><span class="ss">running</span><span class="p" data-group-id="3747922763-58">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                 </span><span class="p" data-group-id="3747922763-59">{</span><span class="s">&quot;Parent&quot;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3747922763-59">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                 </span><span class="p" data-group-id="3747922763-60">{</span><span class="s">&quot;Modules&quot;</span><span class="p">,</span><span class="p" data-group-id="3747922763-61">[</span><span class="ss">code_lock</span><span class="p" data-group-id="3747922763-61">]</span><span class="p" data-group-id="3747922763-60">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                 </span><span class="p" data-group-id="3747922763-62">{</span><span class="s">&quot;Time-outs&quot;</span><span class="p">,</span><span class="p" data-group-id="3747922763-63">{</span><span class="mi">0</span><span class="p">,</span><span class="p" data-group-id="3747922763-64">[</span><span class="p" data-group-id="3747922763-64">]</span><span class="p" data-group-id="3747922763-63">}</span><span class="p" data-group-id="3747922763-62">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                 </span><span class="p" data-group-id="3747922763-65">{</span><span class="s">&quot;Logged Events&quot;</span><span class="p">,</span><span class="p" data-group-id="3747922763-66">[</span><span class="p" data-group-id="3747922763-66">]</span><span class="p" data-group-id="3747922763-65">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                 </span><span class="p" data-group-id="3747922763-67">{</span><span class="s">&quot;Postponed&quot;</span><span class="p">,</span><span class="p" data-group-id="3747922763-68">[</span><span class="p" data-group-id="3747922763-68">]</span><span class="p" data-group-id="3747922763-67">}</span><span class="p" data-group-id="3747922763-57">]</span><span class="p" data-group-id="3747922763-56">}</span><span class="p">,</span><span class="w">
│ │ │ │ +          </span><span class="p" data-group-id="3747922763-69">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="3747922763-70">[</span><span class="p" data-group-id="3747922763-71">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +                  </span><span class="p" data-group-id="3747922763-72">{</span><span class="ss">locked</span><span class="p">,</span><span class="p" data-group-id="3747922763-73">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3747922763-74">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3747922763-74">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                            </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3747922763-75">[</span><span class="p" data-group-id="3747922763-75">]</span><span class="p" data-group-id="3747922763-73">}</span><span class="p" data-group-id="3747922763-72">}</span><span class="p" data-group-id="3747922763-71">}</span><span class="p" data-group-id="3747922763-70">]</span><span class="p" data-group-id="3747922763-69">}</span><span class="p" data-group-id="3747922763-54">]</span><span class="p" data-group-id="3747922763-47">]</span><span class="p" data-group-id="3747922763-45">}</span></code></pre><h2 id="special-processes" class="section-heading">
│ │ │ │    <a href="#special-processes" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Special Processes</span>
│ │ │ │  </h2>
│ │ │ │  <p>This section describes how to write a process that complies to the OTP design
│ │ │ │  principles, without using a standard behaviour. Such a process is to:</p><ul><li>Be started in a way that makes the process fit into a supervision tree</li><li>Support the <code class="inline">sys</code> <a href="spec_proc.xhtml#debug">debug facilities</a></li><li>Take care of <a href="spec_proc.xhtml#msg">system messages</a>.</li></ul><p>System messages are messages with a special meaning, used in the supervision
│ │ │ │ @@ -103,238 +103,238 @@
│ │ │ │    <a href="#example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Example</span>
│ │ │ │  </h3>
│ │ │ │  <p>Here follows the simple server from
│ │ │ │  <a href="design_principles.xhtml#ch1">Overview</a>,
│ │ │ │ -implemented using <code class="inline">sys</code> and <code class="inline">proc_lib</code> to fit into a supervision tree:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0944736124-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="0944736124-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0944736124-2">(</span><span class="p" data-group-id="0944736124-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0944736124-3">]</span><span class="p" data-group-id="0944736124-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0944736124-4">(</span><span class="p" data-group-id="0944736124-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0944736124-5">]</span><span class="p" data-group-id="0944736124-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0944736124-6">(</span><span class="p" data-group-id="0944736124-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0944736124-7">]</span><span class="p" data-group-id="0944736124-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0944736124-8">(</span><span class="p" data-group-id="0944736124-9">[</span><span class="ss">system_continue</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">system_terminate</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w">
│ │ │ │ +implemented using <code class="inline">sys</code> and <code class="inline">proc_lib</code> to fit into a supervision tree:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6649519063-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="6649519063-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6649519063-2">(</span><span class="p" data-group-id="6649519063-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6649519063-3">]</span><span class="p" data-group-id="6649519063-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6649519063-4">(</span><span class="p" data-group-id="6649519063-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6649519063-5">]</span><span class="p" data-group-id="6649519063-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6649519063-6">(</span><span class="p" data-group-id="6649519063-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6649519063-7">]</span><span class="p" data-group-id="6649519063-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6649519063-8">(</span><span class="p" data-group-id="6649519063-9">[</span><span class="ss">system_continue</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">system_terminate</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w">
│ │ │ │           </span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="ss">system_get_state</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">system_replace_state</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0944736124-9">]</span><span class="p" data-group-id="0944736124-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +         </span><span class="ss">system_get_state</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">system_replace_state</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6649519063-9">]</span><span class="p" data-group-id="6649519063-8">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="0944736124-10">(</span><span class="p" data-group-id="0944736124-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0944736124-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-12">[</span><span class="nf">self</span><span class="p" data-group-id="0944736124-13">(</span><span class="p" data-group-id="0944736124-13">)</span><span class="p" data-group-id="0944736124-12">]</span><span class="p" data-group-id="0944736124-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="6649519063-10">(</span><span class="p" data-group-id="6649519063-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="6649519063-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-12">[</span><span class="nf">self</span><span class="p" data-group-id="6649519063-13">(</span><span class="p" data-group-id="6649519063-13">)</span><span class="p" data-group-id="6649519063-12">]</span><span class="p" data-group-id="6649519063-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="0944736124-14">(</span><span class="p" data-group-id="0944736124-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0944736124-15">{</span><span class="nf">self</span><span class="p" data-group-id="0944736124-16">(</span><span class="p" data-group-id="0944736124-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="0944736124-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="6649519063-14">(</span><span class="p" data-group-id="6649519063-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6649519063-15">{</span><span class="nf">self</span><span class="p" data-group-id="6649519063-16">(</span><span class="p" data-group-id="6649519063-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="6649519063-15">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0944736124-17">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="0944736124-17">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="6649519063-17">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="6649519063-17">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="n">Res</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="0944736124-18">(</span><span class="n">Ch</span><span class="p" data-group-id="0944736124-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0944736124-19">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0944736124-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="6649519063-18">(</span><span class="n">Ch</span><span class="p" data-group-id="6649519063-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6649519063-19">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6649519063-19">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="0944736124-20">(</span><span class="n">Parent</span><span class="p" data-group-id="0944736124-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="0944736124-21">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0944736124-22">(</span><span class="p" data-group-id="0944736124-22">)</span><span class="p" data-group-id="0944736124-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="0944736124-23">(</span><span class="p" data-group-id="0944736124-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="0944736124-24">(</span><span class="p" data-group-id="0944736124-25">[</span><span class="p" data-group-id="0944736124-25">]</span><span class="p" data-group-id="0944736124-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="0944736124-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0944736124-28">(</span><span class="p" data-group-id="0944736124-28">)</span><span class="p" data-group-id="0944736124-27">}</span><span class="p" data-group-id="0944736124-26">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="0944736124-29">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="0944736124-29">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="6649519063-20">(</span><span class="n">Parent</span><span class="p" data-group-id="6649519063-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="6649519063-21">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6649519063-22">(</span><span class="p" data-group-id="6649519063-22">)</span><span class="p" data-group-id="6649519063-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="6649519063-23">(</span><span class="p" data-group-id="6649519063-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="6649519063-24">(</span><span class="p" data-group-id="6649519063-25">[</span><span class="p" data-group-id="6649519063-25">]</span><span class="p" data-group-id="6649519063-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="6649519063-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6649519063-28">(</span><span class="p" data-group-id="6649519063-28">)</span><span class="p" data-group-id="6649519063-27">}</span><span class="p" data-group-id="6649519063-26">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="6649519063-29">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="6649519063-29">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="0944736124-30">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="0944736124-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="6649519063-30">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="6649519063-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0944736124-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="0944736124-31">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="0944736124-32">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-33">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="0944736124-33">}</span><span class="p" data-group-id="0944736124-32">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="0944736124-34">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="0944736124-34">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="0944736124-35">(</span><span class="n">Chs</span><span class="p" data-group-id="0944736124-35">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0944736124-36">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0944736124-36">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="0944736124-37">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-38">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-39">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0944736124-39">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="0944736124-38">}</span><span class="p" data-group-id="0944736124-37">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="0944736124-40">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="0944736124-40">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0944736124-41">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0944736124-41">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="0944736124-42">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-43">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-44">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0944736124-44">}</span><span class="p" data-group-id="0944736124-43">}</span><span class="p" data-group-id="0944736124-42">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="0944736124-45">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0944736124-45">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="0944736124-46">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="0944736124-46">)</span><span class="p">;</span><span class="w">
│ │ │ │ -
│ │ │ │ -        </span><span class="p" data-group-id="0944736124-47">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="0944736124-47">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="0944736124-48">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ │ -                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0944736124-48">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="6649519063-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="6649519063-31">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="6649519063-32">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-33">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="6649519063-33">}</span><span class="p" data-group-id="6649519063-32">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="6649519063-34">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="6649519063-34">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="6649519063-35">(</span><span class="n">Chs</span><span class="p" data-group-id="6649519063-35">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6649519063-36">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6649519063-36">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="6649519063-37">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-38">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-39">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6649519063-39">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="6649519063-38">}</span><span class="p" data-group-id="6649519063-37">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="6649519063-40">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="6649519063-40">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="6649519063-41">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6649519063-41">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="6649519063-42">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-43">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-44">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6649519063-44">}</span><span class="p" data-group-id="6649519063-43">}</span><span class="p" data-group-id="6649519063-42">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="6649519063-45">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6649519063-45">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="6649519063-46">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="6649519063-46">)</span><span class="p">;</span><span class="w">
│ │ │ │ +
│ │ │ │ +        </span><span class="p" data-group-id="6649519063-47">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="6649519063-47">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="6649519063-48">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ │ +                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6649519063-48">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_continue</span><span class="p" data-group-id="0944736124-49">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0944736124-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="0944736124-50">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="0944736124-50">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">system_continue</span><span class="p" data-group-id="6649519063-49">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6649519063-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="6649519063-50">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="6649519063-50">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_terminate</span><span class="p" data-group-id="0944736124-51">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Chs</span><span class="p" data-group-id="0944736124-51">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="0944736124-52">(</span><span class="n">Reason</span><span class="p" data-group-id="0944736124-52">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">system_terminate</span><span class="p" data-group-id="6649519063-51">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Chs</span><span class="p" data-group-id="6649519063-51">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="6649519063-52">(</span><span class="n">Reason</span><span class="p" data-group-id="6649519063-52">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_get_state</span><span class="p" data-group-id="0944736124-53">(</span><span class="n">Chs</span><span class="p" data-group-id="0944736124-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0944736124-54">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0944736124-54">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">system_get_state</span><span class="p" data-group-id="6649519063-53">(</span><span class="n">Chs</span><span class="p" data-group-id="6649519063-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6649519063-54">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6649519063-54">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_replace_state</span><span class="p" data-group-id="0944736124-55">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0944736124-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="0944736124-56">(</span><span class="n">Chs</span><span class="p" data-group-id="0944736124-56">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0944736124-57">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="0944736124-57">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">system_replace_state</span><span class="p" data-group-id="6649519063-55">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6649519063-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="6649519063-56">(</span><span class="n">Chs</span><span class="p" data-group-id="6649519063-56">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6649519063-57">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="6649519063-57">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">write_debug</span><span class="p" data-group-id="0944736124-58">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0944736124-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0944736124-59">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944736124-60">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="0944736124-60">]</span><span class="p" data-group-id="0944736124-59">)</span><span class="p">.</span></code></pre><p id="ex">As it is not relevant to the example, the channel handling functions have been
│ │ │ │ +</span><span class="nf">write_debug</span><span class="p" data-group-id="6649519063-58">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="6649519063-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6649519063-59">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6649519063-60">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="6649519063-60">]</span><span class="p" data-group-id="6649519063-59">)</span><span class="p">.</span></code></pre><p id="ex">As it is not relevant to the example, the channel handling functions have been
│ │ │ │  omitted. To compile this example, the
│ │ │ │  <a href="design_principles.xhtml#channels-implementation">implementation of channel handling</a>
│ │ │ │  needs to be added to the module.</p><p>Here is an example showing how the debugging functions in the <code class="inline">sys</code>
│ │ │ │  module can be used for <code class="inline">ch4</code>:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="0962313979-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="0962313979-1">]</span><span class="w"> </span><span class="p" data-group-id="0962313979-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="0962313979-2">]</span><span class="w"> </span><span class="p" data-group-id="0962313979-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0962313979-3">]</span><span class="w"> </span><span class="p" data-group-id="0962313979-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="0962313979-4">]</span><span class="w"> </span><span class="p" data-group-id="0962313979-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="0962313979-5">]</span><span class="w"> </span><span class="p" data-group-id="0962313979-6">[</span><span class="ss">jit</span><span class="p" data-group-id="0962313979-6">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="0301003405-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="0301003405-1">]</span><span class="w"> </span><span class="p" data-group-id="0301003405-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="0301003405-2">]</span><span class="w"> </span><span class="p" data-group-id="0301003405-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0301003405-3">]</span><span class="w"> </span><span class="p" data-group-id="0301003405-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="0301003405-4">]</span><span class="w"> </span><span class="p" data-group-id="0301003405-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="0301003405-5">]</span><span class="w"> </span><span class="p" data-group-id="0301003405-6">[</span><span class="ss">jit</span><span class="p" data-group-id="0301003405-6">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="0962313979-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="0962313979-8">(</span><span class="p" data-group-id="0962313979-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="0962313979-7">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0962313979-9">(</span><span class="p" data-group-id="0962313979-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0962313979-10">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0962313979-10">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="0962313979-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="0962313979-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="0301003405-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="0301003405-8">(</span><span class="p" data-group-id="0301003405-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="0301003405-7">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0301003405-9">(</span><span class="p" data-group-id="0301003405-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0301003405-10">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0301003405-10">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="0301003405-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="0301003405-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="0962313979-12">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="0962313979-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="0301003405-12">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="0301003405-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">alloc</span><span class="p" data-group-id="0962313979-13">(</span><span class="p" data-group-id="0962313979-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0962313979-14">{</span><span class="ss">in</span><span class="p">,</span><span class="ss">alloc</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0962313979-14">}</span><span class="w">
│ │ │ │ -</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0962313979-15">{</span><span class="ss">out</span><span class="p">,</span><span class="p" data-group-id="0962313979-16">{</span><span class="ss">ch4</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0962313979-16">}</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0962313979-15">}</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">alloc</span><span class="p" data-group-id="0301003405-13">(</span><span class="p" data-group-id="0301003405-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0301003405-14">{</span><span class="ss">in</span><span class="p">,</span><span class="ss">alloc</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0301003405-14">}</span><span class="w">
│ │ │ │ +</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0301003405-15">{</span><span class="ss">out</span><span class="p">,</span><span class="p" data-group-id="0301003405-16">{</span><span class="ss">ch4</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0301003405-16">}</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0301003405-15">}</span><span class="w">
│ │ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">free</span><span class="p" data-group-id="0962313979-17">(</span><span class="ss">ch1</span><span class="p" data-group-id="0962313979-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0962313979-18">{</span><span class="ss">in</span><span class="p">,</span><span class="p" data-group-id="0962313979-19">{</span><span class="ss">free</span><span class="p">,</span><span class="ss">ch1</span><span class="p" data-group-id="0962313979-19">}</span><span class="p" data-group-id="0962313979-18">}</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">free</span><span class="p" data-group-id="0301003405-17">(</span><span class="ss">ch1</span><span class="p" data-group-id="0301003405-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0301003405-18">{</span><span class="ss">in</span><span class="p">,</span><span class="p" data-group-id="0301003405-19">{</span><span class="ss">free</span><span class="p">,</span><span class="ss">ch1</span><span class="p" data-group-id="0301003405-19">}</span><span class="p" data-group-id="0301003405-18">}</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="0962313979-20">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="0962313979-20">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0962313979-21">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="0962313979-22">[</span><span class="p" data-group-id="0962313979-23">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="0962313979-24">{</span><span class="p" data-group-id="0962313979-25">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0962313979-25">}</span><span class="p">,</span><span class="p" data-group-id="0962313979-26">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="0962313979-26">}</span><span class="p" data-group-id="0962313979-24">}</span><span class="p" data-group-id="0962313979-23">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="0962313979-27">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="0962313979-28">{</span><span class="p" data-group-id="0962313979-29">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0962313979-29">}</span><span class="p">,</span><span class="p" data-group-id="0962313979-30">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">49</span><span class="p" data-group-id="0962313979-30">}</span><span class="p" data-group-id="0962313979-28">}</span><span class="p" data-group-id="0962313979-27">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="0962313979-31">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">202</span><span class="p" data-group-id="0962313979-31">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="0962313979-32">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0962313979-32">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="0962313979-33">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0962313979-33">}</span><span class="p" data-group-id="0962313979-22">]</span><span class="p" data-group-id="0962313979-21">}</span><span class="gp unselectable">
│ │ │ │ -7&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="0962313979-34">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="0962313979-34">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="0301003405-20">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="0301003405-20">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0301003405-21">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="0301003405-22">[</span><span class="p" data-group-id="0301003405-23">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="0301003405-24">{</span><span class="p" data-group-id="0301003405-25">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0301003405-25">}</span><span class="p">,</span><span class="p" data-group-id="0301003405-26">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="0301003405-26">}</span><span class="p" data-group-id="0301003405-24">}</span><span class="p" data-group-id="0301003405-23">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="0301003405-27">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="0301003405-28">{</span><span class="p" data-group-id="0301003405-29">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0301003405-29">}</span><span class="p">,</span><span class="p" data-group-id="0301003405-30">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">49</span><span class="p" data-group-id="0301003405-30">}</span><span class="p" data-group-id="0301003405-28">}</span><span class="p" data-group-id="0301003405-27">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="0301003405-31">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">202</span><span class="p" data-group-id="0301003405-31">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="0301003405-32">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0301003405-32">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="0301003405-33">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0301003405-33">}</span><span class="p" data-group-id="0301003405-22">]</span><span class="p" data-group-id="0301003405-21">}</span><span class="gp unselectable">
│ │ │ │ +7&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="0301003405-34">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="0301003405-34">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="0962313979-35">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="0962313979-35">)</span><span class="p">.</span><span class="w">
│ │ │ │ +8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="0301003405-35">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="0301003405-35">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="0962313979-36">(</span><span class="ss">ch4</span><span class="p" data-group-id="0962313979-36">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0962313979-37">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0962313979-38">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">ch4</span><span class="p" data-group-id="0962313979-38">}</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0962313979-39">[</span><span class="p" data-group-id="0962313979-40">[</span><span class="p" data-group-id="0962313979-41">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="0962313979-42">{</span><span class="ss">ch4</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0962313979-42">}</span><span class="p" data-group-id="0962313979-41">}</span><span class="p">,</span><span class="w">
│ │ │ │ -          </span><span class="p" data-group-id="0962313979-43">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="0962313979-44">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ -                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0962313979-44">]</span><span class="p" data-group-id="0962313979-43">}</span><span class="p" data-group-id="0962313979-40">]</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="0962313979-45">[</span><span class="p" data-group-id="0962313979-45">]</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="0962313979-46">{</span><span class="p" data-group-id="0962313979-47">[</span><span class="mi">1</span><span class="p" data-group-id="0962313979-47">]</span><span class="p">,</span><span class="p" data-group-id="0962313979-48">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">18</span><span class="p">,</span><span class="mi">19</span><span class="p">|</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0962313979-48">]</span><span class="p" data-group-id="0962313979-46">}</span><span class="p" data-group-id="0962313979-39">]</span><span class="p" data-group-id="0962313979-37">}</span></code></pre><h3 id="starting-the-process" class="section-heading">
│ │ │ │ +9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="0301003405-36">(</span><span class="ss">ch4</span><span class="p" data-group-id="0301003405-36">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0301003405-37">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0301003405-38">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">ch4</span><span class="p" data-group-id="0301003405-38">}</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0301003405-39">[</span><span class="p" data-group-id="0301003405-40">[</span><span class="p" data-group-id="0301003405-41">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="0301003405-42">{</span><span class="ss">ch4</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0301003405-42">}</span><span class="p" data-group-id="0301003405-41">}</span><span class="p">,</span><span class="w">
│ │ │ │ +          </span><span class="p" data-group-id="0301003405-43">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="0301003405-44">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ +                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0301003405-44">]</span><span class="p" data-group-id="0301003405-43">}</span><span class="p" data-group-id="0301003405-40">]</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="0301003405-45">[</span><span class="p" data-group-id="0301003405-45">]</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="0301003405-46">{</span><span class="p" data-group-id="0301003405-47">[</span><span class="mi">1</span><span class="p" data-group-id="0301003405-47">]</span><span class="p">,</span><span class="p" data-group-id="0301003405-48">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">18</span><span class="p">,</span><span class="mi">19</span><span class="p">|</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0301003405-48">]</span><span class="p" data-group-id="0301003405-46">}</span><span class="p" data-group-id="0301003405-39">]</span><span class="p" data-group-id="0301003405-37">}</span></code></pre><h3 id="starting-the-process" class="section-heading">
│ │ │ │    <a href="#starting-the-process" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting the Process</span>
│ │ │ │  </h3>
│ │ │ │  <p>A function in the <a href="../../../lib/stdlib/doc/html/proc_lib.html"><code class="inline">proc_lib</code></a> module is to be used to start the process. Several
│ │ │ │  functions are available, for example,
│ │ │ │  <a href="../../../lib/stdlib/doc/html/proc_lib.html#spawn_link/4"><code class="inline">proc_lib:spawn_link/3,4</code></a>
│ │ │ │  for asynchronous start and
│ │ │ │  <a href="../../../lib/stdlib/doc/html/proc_lib.html#start_link/5"><code class="inline">proc_lib:start_link/3,4,5</code></a> for synchronous start.</p><p>Information necessary for a process within a supervision tree, such as
│ │ │ │  details on ancestors and the initial call, is stored when a process
│ │ │ │  is started through one of these functions.</p><p>If the process terminates with a reason other than <code class="inline">normal</code> or <code class="inline">shutdown</code>, a
│ │ │ │  crash report is generated. For more information about the crash report, see
│ │ │ │  <a href="../../../lib/kernel/doc/html/logger_chapter.xhtml">Logging</a> in Kernel User's Guide.</p><p>In the example, synchronous start is used. The process starts by calling
│ │ │ │ -<code class="inline">ch4:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="0866711553-1">(</span><span class="p" data-group-id="0866711553-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0866711553-2">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0866711553-3">[</span><span class="nf">self</span><span class="p" data-group-id="0866711553-4">(</span><span class="p" data-group-id="0866711553-4">)</span><span class="p" data-group-id="0866711553-3">]</span><span class="p" data-group-id="0866711553-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch4:start_link/0</code> calls <a href="../../../lib/stdlib/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a>, which takes a module
│ │ │ │ +<code class="inline">ch4:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="1794034187-1">(</span><span class="p" data-group-id="1794034187-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1794034187-2">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1794034187-3">[</span><span class="nf">self</span><span class="p" data-group-id="1794034187-4">(</span><span class="p" data-group-id="1794034187-4">)</span><span class="p" data-group-id="1794034187-3">]</span><span class="p" data-group-id="1794034187-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch4:start_link/0</code> calls <a href="../../../lib/stdlib/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a>, which takes a module
│ │ │ │  name, a function name, and an argument list as arguments. It then
│ │ │ │  spawns a new process and establishes a link. The new process starts
│ │ │ │  by executing the given function, here <code class="inline">ch4:init(Pid)</code>, where <code class="inline">Pid</code> is
│ │ │ │  the pid of the parent process (obtained by the call to
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#self/0"><code class="inline">self()</code></a> in the call to <a href="../../../lib/stdlib/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a>).</p><p>All initialization, including name registration, is done in <code class="inline">init/1</code>. The new
│ │ │ │ -process has to acknowledge that it has been started to the parent:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1787751300-1">(</span><span class="n">Parent</span><span class="p" data-group-id="1787751300-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +process has to acknowledge that it has been started to the parent:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="5595990071-1">(</span><span class="n">Parent</span><span class="p" data-group-id="5595990071-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="1787751300-2">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1787751300-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1787751300-4">(</span><span class="p" data-group-id="1787751300-4">)</span><span class="p" data-group-id="1787751300-3">}</span><span class="p" data-group-id="1787751300-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="1787751300-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1787751300-5">)</span><span class="p">.</span></code></pre><p><a href="../../../lib/stdlib/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a> is synchronous and does not return until
│ │ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="5595990071-2">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5595990071-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5595990071-4">(</span><span class="p" data-group-id="5595990071-4">)</span><span class="p" data-group-id="5595990071-3">}</span><span class="p" data-group-id="5595990071-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="5595990071-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5595990071-5">)</span><span class="p">.</span></code></pre><p><a href="../../../lib/stdlib/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a> is synchronous and does not return until
│ │ │ │  <a href="../../../lib/stdlib/doc/html/proc_lib.html#init_ack/2"><code class="inline">proc_lib:init_ack/1,2</code></a> or
│ │ │ │  <a href="../../../lib/stdlib/doc/html/proc_lib.html#init_fail/3"><code class="inline">proc_lib:init_fail/2,3</code></a> has been called,
│ │ │ │  or the process has exited.</p><p><a href="" id="debug"></a></p><h3 id="debugging" class="section-heading">
│ │ │ │    <a href="#debugging" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Debugging</span>
│ │ │ │  </h3>
│ │ │ │  <p>To support the debug facilities in <code class="inline">sys</code>, a <em>debug structure</em> is needed. The
│ │ │ │ -<code class="inline">Deb</code> term is initialized using <a href="../../../lib/stdlib/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0884207430-1">(</span><span class="n">Parent</span><span class="p" data-group-id="0884207430-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +<code class="inline">Deb</code> term is initialized using <a href="../../../lib/stdlib/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="8374486735-1">(</span><span class="n">Parent</span><span class="p" data-group-id="8374486735-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="0884207430-2">(</span><span class="p" data-group-id="0884207430-3">[</span><span class="p" data-group-id="0884207430-3">]</span><span class="p" data-group-id="0884207430-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="8374486735-2">(</span><span class="p" data-group-id="8374486735-3">[</span><span class="p" data-group-id="8374486735-3">]</span><span class="p" data-group-id="8374486735-2">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="0884207430-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="0884207430-4">)</span><span class="p">.</span></code></pre><p><a href="../../../lib/stdlib/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a> takes a list of options. Given an empty list as in this
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="8374486735-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8374486735-4">)</span><span class="p">.</span></code></pre><p><a href="../../../lib/stdlib/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a> takes a list of options. Given an empty list as in this
│ │ │ │  example means that debugging is initially disabled. For information about the
│ │ │ │  possible options, see <a href="../../../lib/stdlib/doc/html/sys.html"><code class="inline">sys</code></a> in STDLIB.</p><p>For each <em>system event</em> to be logged or traced, the following function
│ │ │ │ -is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="5684223818-1">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Func</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="5684223818-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Deb1</span></code></pre><p>The arguments have the follow meaning:</p><ul><li><code class="inline">Deb</code> is the debug structure as returned from <a href="../../../lib/stdlib/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>.</li><li><code class="inline">Func</code> is a fun specifying a (user-defined) function used to format trace
│ │ │ │ +is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="0602538620-1">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Func</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="0602538620-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Deb1</span></code></pre><p>The arguments have the follow meaning:</p><ul><li><code class="inline">Deb</code> is the debug structure as returned from <a href="../../../lib/stdlib/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>.</li><li><code class="inline">Func</code> is a fun specifying a (user-defined) function used to format trace
│ │ │ │  output. For each system event, the format function is called as
│ │ │ │  <code class="inline">Func(Dev, Event, Info)</code>, where:<ul><li><code class="inline">Dev</code> is the I/O device to which the output is to be printed. See <a href="../../../lib/stdlib/doc/html/io.html"><code class="inline">io</code></a>
│ │ │ │  in STDLIB.</li><li><code class="inline">Event</code> and <code class="inline">Info</code> are passed as-is from the call to <a href="../../../lib/stdlib/doc/html/sys.html#handle_debug/4"><code class="inline">sys:handle_debug/4</code></a>.</li></ul></li><li><code class="inline">Info</code> is used to pass more information to <code class="inline">Func</code>. It can be any term, and it
│ │ │ │  is passed as-is.</li><li><code class="inline">Event</code> is the system event. It is up to the user to define what a system
│ │ │ │  event is and how it is to be represented. Typically, at least incoming and
│ │ │ │  outgoing messages are considered system events and represented by the tuples
│ │ │ │  <code class="inline">{in,Msg[,From]}</code> and <code class="inline">{out,Msg,To[,State]}</code>, respectively.</li></ul><p><a href="../../../lib/stdlib/doc/html/sys.html#handle_debug/4"><code class="inline">sys:handle_debug/4</code></a> returns an updated debug structure <code class="inline">Deb1</code>.</p><p>In the example, <a href="../../../lib/stdlib/doc/html/sys.html#handle_debug/4"><code class="inline">sys:handle_debug/4</code></a> is called for each incoming and
│ │ │ │  outgoing message. The format function <code class="inline">Func</code> is the function
│ │ │ │ -<code class="inline">ch4:write_debug/3</code>, which prints the message using <a href="../../../lib/stdlib/doc/html/io.html#format/3"><code class="inline">io:format/3</code></a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="6632969361-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="6632969361-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +<code class="inline">ch4:write_debug/3</code>, which prints the message using <a href="../../../lib/stdlib/doc/html/io.html#format/3"><code class="inline">io:format/3</code></a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="8730420277-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8730420277-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6632969361-2">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="6632969361-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="6632969361-3">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6632969361-4">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="6632969361-4">}</span><span class="p" data-group-id="6632969361-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6632969361-5">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="6632969361-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="6632969361-6">(</span><span class="n">Chs</span><span class="p" data-group-id="6632969361-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6632969361-7">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6632969361-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="6632969361-8">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6632969361-9">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6632969361-10">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6632969361-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="6632969361-9">}</span><span class="p" data-group-id="6632969361-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="6632969361-11">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="6632969361-11">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6632969361-12">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6632969361-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="6632969361-13">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6632969361-14">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6632969361-15">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6632969361-15">}</span><span class="p" data-group-id="6632969361-14">}</span><span class="p" data-group-id="6632969361-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="6632969361-16">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6632969361-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="6632969361-17">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="6632969361-17">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8730420277-2">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="8730420277-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="8730420277-3">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8730420277-4">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="8730420277-4">}</span><span class="p" data-group-id="8730420277-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="8730420277-5">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="8730420277-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="8730420277-6">(</span><span class="n">Chs</span><span class="p" data-group-id="8730420277-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8730420277-7">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8730420277-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="8730420277-8">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8730420277-9">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8730420277-10">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8730420277-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="8730420277-9">}</span><span class="p" data-group-id="8730420277-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="8730420277-11">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="8730420277-11">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8730420277-12">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8730420277-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="8730420277-13">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8730420277-14">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8730420277-15">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8730420277-15">}</span><span class="p" data-group-id="8730420277-14">}</span><span class="p" data-group-id="8730420277-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="8730420277-16">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8730420277-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="8730420277-17">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="8730420277-17">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">write_debug</span><span class="p" data-group-id="6632969361-18">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="6632969361-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6632969361-19">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6632969361-20">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="6632969361-20">]</span><span class="p" data-group-id="6632969361-19">)</span><span class="p">.</span></code></pre><p><a href="" id="msg"></a></p><h3 id="handling-system-messages" class="section-heading">
│ │ │ │ +</span><span class="nf">write_debug</span><span class="p" data-group-id="8730420277-18">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8730420277-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8730420277-19">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8730420277-20">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="8730420277-20">]</span><span class="p" data-group-id="8730420277-19">)</span><span class="p">.</span></code></pre><p><a href="" id="msg"></a></p><h3 id="handling-system-messages" class="section-heading">
│ │ │ │    <a href="#handling-system-messages" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Handling System Messages</span>
│ │ │ │  </h3>
│ │ │ │  <p><em>System messages</em> are received as:</p><pre><code class="text">{system, From, Request}</code></pre><p>The content and meaning of these messages are not to be interpreted by the
│ │ │ │ -process. Instead the following function is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="3074641396-1">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3074641396-1">)</span></code></pre><p>The arguments have the following meaning:</p><ul><li><code class="inline">Request</code> and <code class="inline">From</code> from the received system message are to be
│ │ │ │ +process. Instead the following function is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="4706598898-1">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4706598898-1">)</span></code></pre><p>The arguments have the following meaning:</p><ul><li><code class="inline">Request</code> and <code class="inline">From</code> from the received system message are to be
│ │ │ │  passed as-is to the call to <a href="../../../lib/stdlib/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg/6</code></a>.</li><li><code class="inline">Parent</code> is the pid of the parent process.</li><li><code class="inline">Module</code> is the name of the module implementing the speciall process.</li><li><code class="inline">Deb</code> is the debug structure.</li><li><code class="inline">State</code> is a term describing the internal state and is passed on to
│ │ │ │  <code class="inline">Module:system_continue/3</code>, <code class="inline">Module:system_terminate/4</code>/
│ │ │ │  <code class="inline">Module:system_get_state/1</code>, and <code class="inline">Module:system_replace_state/2</code>.</li></ul><p><a href="../../../lib/stdlib/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg/6</code></a> does not return. It handles the system
│ │ │ │  message and <em>eventually</em> calls either of the following functions:</p><ul><li><p><code class="inline">Module:system_continue(Parent, Deb, State)</code> - if process execution is to
│ │ │ │  continue.</p></li><li><p><code class="inline">Module:system_terminate(Reason, Parent, Deb, State)</code> - if the
│ │ │ │  process is to terminate.</p></li></ul><p>While handling the system message, <a href="../../../lib/stdlib/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg/6</code></a> can call
│ │ │ │  one of the following functions:</p><ul><li><p><code class="inline">Module:system_get_state(State)</code> - if the process is to return its state.</p></li><li><p><code class="inline">Module:system_replace_state(StateFun, State)</code> - if the process is
│ │ │ │  to replace its state using the fun <code class="inline">StateFun</code> fun. See <a href="../../../lib/stdlib/doc/html/sys.html#replace_state/3"><code class="inline">sys:replace_state/3</code></a>
│ │ │ │  for more information.</p></li><li><p><code class="inline">system_code_change(Misc, Module, OldVsn, Extra)</code> - if the process is to
│ │ │ │  perform a code change.</p></li></ul><p>A process in a supervision tree is expected to terminate with the same reason as
│ │ │ │ -its parent.</p><p>In the example, system messages are handed by the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="8765152442-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8765152442-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +its parent.</p><p>In the example, system messages are handed by the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="8875825676-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8875825676-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -        </span><span class="p" data-group-id="8765152442-2">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="8765152442-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="8765152442-3">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ │ -                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8765152442-3">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8875825676-2">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="8875825676-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="8875825676-3">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ │ +                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8875825676-3">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_continue</span><span class="p" data-group-id="8765152442-4">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8765152442-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="8765152442-5">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8765152442-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">system_continue</span><span class="p" data-group-id="8875825676-4">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8875825676-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="8875825676-5">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8875825676-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_terminate</span><span class="p" data-group-id="8765152442-6">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8765152442-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="8765152442-7">(</span><span class="n">Reason</span><span class="p" data-group-id="8765152442-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">system_terminate</span><span class="p" data-group-id="8875825676-6">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8875825676-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="8875825676-7">(</span><span class="n">Reason</span><span class="p" data-group-id="8875825676-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_get_state</span><span class="p" data-group-id="8765152442-8">(</span><span class="n">Chs</span><span class="p" data-group-id="8765152442-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8765152442-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8765152442-9">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">system_get_state</span><span class="p" data-group-id="8875825676-8">(</span><span class="n">Chs</span><span class="p" data-group-id="8875825676-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8875825676-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8875825676-9">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_replace_state</span><span class="p" data-group-id="8765152442-10">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8765152442-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="8765152442-11">(</span><span class="n">Chs</span><span class="p" data-group-id="8765152442-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8765152442-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="8765152442-12">}</span><span class="p">.</span></code></pre><p>If a special process is configured to trap exits, it must take notice
│ │ │ │ +</span><span class="nf">system_replace_state</span><span class="p" data-group-id="8875825676-10">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8875825676-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="8875825676-11">(</span><span class="n">Chs</span><span class="p" data-group-id="8875825676-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8875825676-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="8875825676-12">}</span><span class="p">.</span></code></pre><p>If a special process is configured to trap exits, it must take notice
│ │ │ │  of 'EXIT' messages from its parent process and terminate using the
│ │ │ │ -same exit reason once the parent process has terminated.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1105179534-1">(</span><span class="n">Parent</span><span class="p" data-group-id="1105179534-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +same exit reason once the parent process has terminated.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="4879651583-1">(</span><span class="n">Parent</span><span class="p" data-group-id="4879651583-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="1105179534-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="1105179534-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="4879651583-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="4879651583-2">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="1105179534-3">(</span><span class="n">Parent</span><span class="p" data-group-id="1105179534-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="4879651583-3">(</span><span class="n">Parent</span><span class="p" data-group-id="4879651583-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="1105179534-4">(</span><span class="n">Parent</span><span class="p" data-group-id="1105179534-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="4879651583-4">(</span><span class="n">Parent</span><span class="p" data-group-id="4879651583-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1105179534-5">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="1105179534-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="4879651583-5">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="4879651583-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="c1">%% Clean up here, if needed.</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="1105179534-6">(</span><span class="n">Reason</span><span class="p" data-group-id="1105179534-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="4879651583-6">(</span><span class="n">Reason</span><span class="p" data-group-id="4879651583-6">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><h2 id="user-defined-behaviours" class="section-heading">
│ │ │ │    <a href="#user-defined-behaviours" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">User-Defined Behaviours</span>
│ │ │ │  </h2>
│ │ │ │ @@ -353,69 +353,69 @@
│ │ │ │  function. Note that the <code class="inline">-optional_callbacks</code> attribute is to be used together
│ │ │ │  with the <code class="inline">-callback</code> attribute; it cannot be combined with the
│ │ │ │  <code class="inline">behaviour_info()</code> function described below.</p><p>Tools that need to know about optional callback functions can call
│ │ │ │  <code class="inline">Behaviour:behaviour_info(optional_callbacks)</code> to get a list of all optional
│ │ │ │  callback functions.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>We recommend using the <code class="inline">-callback</code> attribute rather than the
│ │ │ │  <code class="inline">behaviour_info()</code> function. The reason is that the extra type information can
│ │ │ │  be used by tools to produce documentation or find discrepancies.</p></section><p>As an alternative to the <code class="inline">-callback</code> and <code class="inline">-optional_callbacks</code> attributes you
│ │ │ │ -may directly implement and export <code class="inline">behaviour_info()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="7063501638-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="7063501638-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7063501638-2">[</span><span class="p" data-group-id="7063501638-3">{</span><span class="n">Name1</span><span class="p">,</span><span class="w"> </span><span class="n">Arity1</span><span class="p" data-group-id="7063501638-3">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="p" data-group-id="7063501638-4">{</span><span class="n">NameN</span><span class="p">,</span><span class="w"> </span><span class="n">ArityN</span><span class="p" data-group-id="7063501638-4">}</span><span class="p" data-group-id="7063501638-2">]</span><span class="p">.</span></code></pre><p>where each <code class="inline">{Name, Arity}</code> specifies the name and arity of a callback function.
│ │ │ │ +may directly implement and export <code class="inline">behaviour_info()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="9691920655-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="9691920655-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9691920655-2">[</span><span class="p" data-group-id="9691920655-3">{</span><span class="n">Name1</span><span class="p">,</span><span class="w"> </span><span class="n">Arity1</span><span class="p" data-group-id="9691920655-3">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="p" data-group-id="9691920655-4">{</span><span class="n">NameN</span><span class="p">,</span><span class="w"> </span><span class="n">ArityN</span><span class="p" data-group-id="9691920655-4">}</span><span class="p" data-group-id="9691920655-2">]</span><span class="p">.</span></code></pre><p>where each <code class="inline">{Name, Arity}</code> specifies the name and arity of a callback function.
│ │ │ │  This function is otherwise automatically generated by the compiler using the
│ │ │ │  <code class="inline">-callback</code> attributes.</p><p>When the compiler encounters the module attribute <code class="inline">-behaviour(Behaviour).</code> in a
│ │ │ │  module <code class="inline">Mod</code>, it calls <code class="inline">Behaviour:behaviour_info(callbacks)</code> and compares the
│ │ │ │  result with the set of functions actually exported from <code class="inline">Mod</code>, and issues a
│ │ │ │  warning if any callback function is missing.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">%% User-defined behaviour module</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1517007866-1">(</span><span class="ss">simple_server</span><span class="p" data-group-id="1517007866-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1517007866-2">(</span><span class="p" data-group-id="1517007866-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1517007866-3">]</span><span class="p" data-group-id="1517007866-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4963219654-1">(</span><span class="ss">simple_server</span><span class="p" data-group-id="4963219654-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4963219654-2">(</span><span class="p" data-group-id="4963219654-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4963219654-3">]</span><span class="p" data-group-id="4963219654-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">init</span><span class="p" data-group-id="1517007866-4">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="1517007866-5">(</span><span class="p" data-group-id="1517007866-5">)</span><span class="p" data-group-id="1517007866-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="1517007866-6">(</span><span class="n">Req</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="1517007866-7">(</span><span class="p" data-group-id="1517007866-7">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="1517007866-8">(</span><span class="p" data-group-id="1517007866-8">)</span><span class="p" data-group-id="1517007866-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1517007866-9">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="1517007866-10">(</span><span class="p" data-group-id="1517007866-10">)</span><span class="p" data-group-id="1517007866-9">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">terminate</span><span class="p" data-group-id="1517007866-11">(</span><span class="p" data-group-id="1517007866-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">format_state</span><span class="p" data-group-id="1517007866-12">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="1517007866-13">(</span><span class="p" data-group-id="1517007866-13">)</span><span class="p" data-group-id="1517007866-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="1517007866-14">(</span><span class="p" data-group-id="1517007866-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">init</span><span class="p" data-group-id="4963219654-4">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="4963219654-5">(</span><span class="p" data-group-id="4963219654-5">)</span><span class="p" data-group-id="4963219654-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="4963219654-6">(</span><span class="n">Req</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="4963219654-7">(</span><span class="p" data-group-id="4963219654-7">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="4963219654-8">(</span><span class="p" data-group-id="4963219654-8">)</span><span class="p" data-group-id="4963219654-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4963219654-9">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="4963219654-10">(</span><span class="p" data-group-id="4963219654-10">)</span><span class="p" data-group-id="4963219654-9">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">terminate</span><span class="p" data-group-id="4963219654-11">(</span><span class="p" data-group-id="4963219654-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">format_state</span><span class="p" data-group-id="4963219654-12">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="4963219654-13">(</span><span class="p" data-group-id="4963219654-13">)</span><span class="p" data-group-id="4963219654-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="4963219654-14">(</span><span class="p" data-group-id="4963219654-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">optional_callbacks</span><span class="p" data-group-id="1517007866-15">(</span><span class="p" data-group-id="1517007866-16">[</span><span class="ss">format_state</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1517007866-16">]</span><span class="p" data-group-id="1517007866-15">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">optional_callbacks</span><span class="p" data-group-id="4963219654-15">(</span><span class="p" data-group-id="4963219654-16">[</span><span class="ss">format_state</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4963219654-16">]</span><span class="p" data-group-id="4963219654-15">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% Alternatively you may define:</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │  </span><span class="c1">%% -export([behaviour_info/1]).</span><span class="w">
│ │ │ │  </span><span class="c1">%% behaviour_info(callbacks) -&gt;</span><span class="w">
│ │ │ │  </span><span class="c1">%%     [{init,1},</span><span class="w">
│ │ │ │  </span><span class="c1">%%      {handle_req,2},</span><span class="w">
│ │ │ │  </span><span class="c1">%%      {terminate,0}].</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="1517007866-17">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="1517007866-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1517007866-18">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1517007866-19">[</span><span class="nf">self</span><span class="p" data-group-id="1517007866-20">(</span><span class="p" data-group-id="1517007866-20">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="1517007866-19">]</span><span class="p" data-group-id="1517007866-18">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="4963219654-17">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="4963219654-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="4963219654-18">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4963219654-19">[</span><span class="nf">self</span><span class="p" data-group-id="4963219654-20">(</span><span class="p" data-group-id="4963219654-20">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="4963219654-19">]</span><span class="p" data-group-id="4963219654-18">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="1517007866-21">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="1517007866-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="1517007866-22">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1517007866-23">(</span><span class="p" data-group-id="1517007866-23">)</span><span class="p" data-group-id="1517007866-22">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="4963219654-21">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="4963219654-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="4963219654-22">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4963219654-23">(</span><span class="p" data-group-id="4963219654-23">)</span><span class="p" data-group-id="4963219654-22">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Dbg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="1517007866-24">(</span><span class="p" data-group-id="1517007866-25">[</span><span class="p" data-group-id="1517007866-25">]</span><span class="p" data-group-id="1517007866-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="1517007866-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1517007866-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1517007866-28">(</span><span class="p" data-group-id="1517007866-28">)</span><span class="p" data-group-id="1517007866-27">}</span><span class="p" data-group-id="1517007866-26">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="1517007866-29">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1517007866-29">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="n">Dbg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="4963219654-24">(</span><span class="p" data-group-id="4963219654-25">[</span><span class="p" data-group-id="4963219654-25">]</span><span class="p" data-group-id="4963219654-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="4963219654-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4963219654-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4963219654-28">(</span><span class="p" data-group-id="4963219654-28">)</span><span class="p" data-group-id="4963219654-27">}</span><span class="p" data-group-id="4963219654-26">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="4963219654-29">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4963219654-29">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>In a callback module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7415403107-1">(</span><span class="ss">db</span><span class="p" data-group-id="7415403107-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="7415403107-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="7415403107-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>In a callback module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9552843401-1">(</span><span class="ss">db</span><span class="p" data-group-id="9552843401-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9552843401-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="9552843401-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7415403107-3">(</span><span class="p" data-group-id="7415403107-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7415403107-4">]</span><span class="p" data-group-id="7415403107-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9552843401-3">(</span><span class="p" data-group-id="9552843401-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9552843401-4">]</span><span class="p" data-group-id="9552843401-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The contracts specified with <code class="inline">-callback</code> attributes in behaviour modules can be
│ │ │ │  further refined by adding <code class="inline">-spec</code> attributes in callback modules. This can be
│ │ │ │  useful as <code class="inline">-callback</code> contracts are usually generic. The same callback module
│ │ │ │ -with contracts for the callbacks:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5646962699-1">(</span><span class="ss">db</span><span class="p" data-group-id="5646962699-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5646962699-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="5646962699-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +with contracts for the callbacks:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7534935771-1">(</span><span class="ss">db</span><span class="p" data-group-id="7534935771-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="7534935771-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="7534935771-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5646962699-3">(</span><span class="p" data-group-id="5646962699-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5646962699-4">]</span><span class="p" data-group-id="5646962699-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7534935771-3">(</span><span class="p" data-group-id="7534935771-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7534935771-4">]</span><span class="p" data-group-id="7534935771-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5646962699-5">(</span><span class="ss">state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5646962699-6">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="5646962699-7">[</span><span class="nf">atom</span><span class="p" data-group-id="5646962699-8">(</span><span class="p" data-group-id="5646962699-8">)</span><span class="p" data-group-id="5646962699-7">]</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="5646962699-9">(</span><span class="p" data-group-id="5646962699-9">)</span><span class="p" data-group-id="5646962699-6">}</span><span class="p" data-group-id="5646962699-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7534935771-5">(</span><span class="ss">state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7534935771-6">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7534935771-7">[</span><span class="nf">atom</span><span class="p" data-group-id="7534935771-8">(</span><span class="p" data-group-id="7534935771-8">)</span><span class="p" data-group-id="7534935771-7">]</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7534935771-9">(</span><span class="p" data-group-id="7534935771-9">)</span><span class="p" data-group-id="7534935771-6">}</span><span class="p" data-group-id="7534935771-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="5646962699-10">(</span><span class="p" data-group-id="5646962699-10">)</span><span class="w">   </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="5646962699-11">{</span><span class="p" data-group-id="5646962699-11">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">request</span><span class="p" data-group-id="5646962699-12">(</span><span class="p" data-group-id="5646962699-12">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="5646962699-13">{</span><span class="ss">&#39;store&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="5646962699-14">(</span><span class="p" data-group-id="5646962699-14">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="5646962699-15">(</span><span class="p" data-group-id="5646962699-15">)</span><span class="p" data-group-id="5646962699-13">}</span><span class="p">;</span><span class="w">
│ │ │ │ -                   </span><span class="p" data-group-id="5646962699-16">{</span><span class="ss">&#39;lookup&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="5646962699-17">(</span><span class="p" data-group-id="5646962699-17">)</span><span class="p" data-group-id="5646962699-16">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="7534935771-10">(</span><span class="p" data-group-id="7534935771-10">)</span><span class="w">   </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="7534935771-11">{</span><span class="p" data-group-id="7534935771-11">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">request</span><span class="p" data-group-id="7534935771-12">(</span><span class="p" data-group-id="7534935771-12">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7534935771-13">{</span><span class="ss">&#39;store&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="7534935771-14">(</span><span class="p" data-group-id="7534935771-14">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="7534935771-15">(</span><span class="p" data-group-id="7534935771-15">)</span><span class="p" data-group-id="7534935771-13">}</span><span class="p">;</span><span class="w">
│ │ │ │ +                   </span><span class="p" data-group-id="7534935771-16">{</span><span class="ss">&#39;lookup&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="7534935771-17">(</span><span class="p" data-group-id="7534935771-17">)</span><span class="p" data-group-id="7534935771-16">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="5646962699-18">(</span><span class="nf">request</span><span class="p" data-group-id="5646962699-19">(</span><span class="p" data-group-id="5646962699-19">)</span><span class="p">,</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="5646962699-20">(</span><span class="p" data-group-id="5646962699-20">)</span><span class="p" data-group-id="5646962699-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5646962699-21">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="5646962699-22">(</span><span class="p" data-group-id="5646962699-22">)</span><span class="p" data-group-id="5646962699-21">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="7534935771-18">(</span><span class="nf">request</span><span class="p" data-group-id="7534935771-19">(</span><span class="p" data-group-id="7534935771-19">)</span><span class="p">,</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="7534935771-20">(</span><span class="p" data-group-id="7534935771-20">)</span><span class="p" data-group-id="7534935771-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7534935771-21">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="7534935771-22">(</span><span class="p" data-group-id="7534935771-22">)</span><span class="p" data-group-id="7534935771-21">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Each <code class="inline">-spec</code> contract is to be a subtype of the respective <code class="inline">-callback</code> contract.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/seq_prog.xhtml
│ │ │ │ @@ -41,293 +41,293 @@
│ │ │ │  </span><span class="mi">7</span><span class="gp unselectable">
│ │ │ │  2&gt; </span></code></pre><p>As shown, the Erlang shell numbers the lines that can be entered, (as 1&gt; 2&gt;) and
│ │ │ │  that it correctly says that 2 + 5 is 7. If you make writing mistakes in the
│ │ │ │  shell, you can delete with the backspace key, as in most shells. There are many
│ │ │ │  more editing commands in the shell (see
│ │ │ │  <a href="../../../lib/../erts/doc/html/tty.xhtml">tty - A command line interface</a> in ERTS User's Guide).</p><p>(Notice that many line numbers given by the shell in the following examples are
│ │ │ │  out of sequence. This is because this tutorial was written and code-tested in
│ │ │ │ -separate sessions).</p><p>Here is a bit more complex calculation:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="2797427540-1">(</span><span class="mi">42</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">77</span><span class="p" data-group-id="2797427540-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">66</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ │ +separate sessions).</p><p>Here is a bit more complex calculation:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="3757155351-1">(</span><span class="mi">42</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">77</span><span class="p" data-group-id="3757155351-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">66</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mf">2618.0</span></code></pre><p>Notice the use of brackets, the multiplication operator <code class="inline">*</code>, and the division
│ │ │ │  operator <code class="inline">/</code>, as in normal arithmetic (see
│ │ │ │  <a href="../../../lib/../system/doc/html/expressions.xhtml">Expressions</a>).</p><p>Press Control-C to shut down the Erlang system and the Erlang shell.</p><p>The following output is shown:</p><pre><code class="text">BREAK: (a)bort (c)ontinue (p)roc info (i)nfo (l)oaded
│ │ │ │         (v)ersion (k)ill (D)b-tables (d)istribution
│ │ │ │  a
│ │ │ │ -$</code></pre><p>Type <code class="inline">a</code> to leave the Erlang system.</p><p>Another way to shut down the Erlang system is by entering <a href="../../../lib/../erts/doc/html/erlang.html#halt/0"><code class="inline">halt/0</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">halt</span><span class="p" data-group-id="8416760308-1">(</span><span class="p" data-group-id="8416760308-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +$</code></pre><p>Type <code class="inline">a</code> to leave the Erlang system.</p><p>Another way to shut down the Erlang system is by entering <a href="../../../lib/../erts/doc/html/erlang.html#halt/0"><code class="inline">halt/0</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">halt</span><span class="p" data-group-id="2007691246-1">(</span><span class="p" data-group-id="2007691246-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="err">$</span></code></pre><h2 id="modules-and-functions" class="section-heading">
│ │ │ │    <a href="#modules-and-functions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Modules and Functions</span>
│ │ │ │  </h2>
│ │ │ │  <p>A programming language is not much use if you only can run code from the shell.
│ │ │ │  So here is a small Erlang program. Enter it into a file named <code class="inline">tut.erl</code> using a
│ │ │ │  suitable text editor. The file name <code class="inline">tut.erl</code> is important, and also that it is
│ │ │ │  in the same directory as the one where you started <code class="inline">erl</code>). If you are lucky your
│ │ │ │  editor has an Erlang mode that makes it easier for you to enter and format your
│ │ │ │  code nicely (see <a href="../../../lib/tools/doc/html/erlang_mode_chapter.xhtml">The Erlang mode for Emacs</a>
│ │ │ │  in Tools User's Guide), but you can manage perfectly well without. Here is the
│ │ │ │ -code to enter:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3267974168-1">(</span><span class="ss">tut</span><span class="p" data-group-id="3267974168-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3267974168-2">(</span><span class="p" data-group-id="3267974168-3">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3267974168-3">]</span><span class="p" data-group-id="3267974168-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +code to enter:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3897248666-1">(</span><span class="ss">tut</span><span class="p" data-group-id="3897248666-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3897248666-2">(</span><span class="p" data-group-id="3897248666-3">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3897248666-3">]</span><span class="p" data-group-id="3897248666-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">double</span><span class="p" data-group-id="3267974168-4">(</span><span class="n">X</span><span class="p" data-group-id="3267974168-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">double</span><span class="p" data-group-id="3897248666-4">(</span><span class="n">X</span><span class="p" data-group-id="3897248666-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="p">.</span></code></pre><p>It is not hard to guess that this program doubles the value of numbers. The
│ │ │ │  first two lines of the code are described later. Let us compile the program.
│ │ │ │ -This can be done in an Erlang shell as follows, where <code class="inline">c</code> means compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">c</span><span class="p" data-group-id="0727917798-1">(</span><span class="ss">tut</span><span class="p" data-group-id="0727917798-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0727917798-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut</span><span class="p" data-group-id="0727917798-2">}</span></code></pre><p>The <code class="inline">{ok,tut}</code> means that the compilation is OK. If it says <code class="inline">error</code> it means
│ │ │ │ +This can be done in an Erlang shell as follows, where <code class="inline">c</code> means compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">c</span><span class="p" data-group-id="6052420275-1">(</span><span class="ss">tut</span><span class="p" data-group-id="6052420275-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6052420275-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut</span><span class="p" data-group-id="6052420275-2">}</span></code></pre><p>The <code class="inline">{ok,tut}</code> means that the compilation is OK. If it says <code class="inline">error</code> it means
│ │ │ │  that there is some mistake in the text that you entered. Additional error
│ │ │ │  messages gives an idea to what is wrong so you can modify the text and then try
│ │ │ │ -to compile the program again.</p><p>Now run the program:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="1274382157-1">(</span><span class="mi">10</span><span class="p" data-group-id="1274382157-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +to compile the program again.</p><p>Now run the program:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="4872104630-1">(</span><span class="mi">10</span><span class="p" data-group-id="4872104630-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">20</span></code></pre><p>As expected, double of 10 is 20.</p><p>Now let us get back to the first two lines of the code. Erlang programs are
│ │ │ │  written in files. Each file contains an Erlang <em>module</em>. The first line of code
│ │ │ │ -in the module is the module name (see <a href="../../../lib/../system/doc/html/modules.xhtml">Modules</a>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7606605061-1">(</span><span class="ss">tut</span><span class="p" data-group-id="7606605061-1">)</span><span class="p">.</span></code></pre><p>Thus, the module is called <em>tut</em>. Notice the full stop <code class="inline">.</code> at the end of the
│ │ │ │ +in the module is the module name (see <a href="../../../lib/../system/doc/html/modules.xhtml">Modules</a>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4532037078-1">(</span><span class="ss">tut</span><span class="p" data-group-id="4532037078-1">)</span><span class="p">.</span></code></pre><p>Thus, the module is called <em>tut</em>. Notice the full stop <code class="inline">.</code> at the end of the
│ │ │ │  line. The files which are used to store the module must have the same name as
│ │ │ │  the module but with the extension <code class="inline">.erl</code>. In this case the file name is
│ │ │ │  <code class="inline">tut.erl</code>. When using a function in another module, the syntax
│ │ │ │  <code class="inline">module_name:function_name(arguments)</code> is used. So the following means call
│ │ │ │ -function <code class="inline">double</code> in module <code class="inline">tut</code> with argument <code class="inline">10</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="9044773080-1">(</span><span class="mi">10</span><span class="p" data-group-id="9044773080-1">)</span><span class="p">.</span></code></pre><p>The second line says that the module <code class="inline">tut</code> contains a function called <code class="inline">double</code>,
│ │ │ │ -which takes one argument (<code class="inline">X</code> in our example):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2240193715-1">(</span><span class="p" data-group-id="2240193715-2">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2240193715-2">]</span><span class="p" data-group-id="2240193715-1">)</span><span class="p">.</span></code></pre><p>The second line also says that this function can be called from outside the
│ │ │ │ +function <code class="inline">double</code> in module <code class="inline">tut</code> with argument <code class="inline">10</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="2074323920-1">(</span><span class="mi">10</span><span class="p" data-group-id="2074323920-1">)</span><span class="p">.</span></code></pre><p>The second line says that the module <code class="inline">tut</code> contains a function called <code class="inline">double</code>,
│ │ │ │ +which takes one argument (<code class="inline">X</code> in our example):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7153766823-1">(</span><span class="p" data-group-id="7153766823-2">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7153766823-2">]</span><span class="p" data-group-id="7153766823-1">)</span><span class="p">.</span></code></pre><p>The second line also says that this function can be called from outside the
│ │ │ │  module <code class="inline">tut</code>. More about this later. Again, notice the <code class="inline">.</code> at the end of the
│ │ │ │  line.</p><p>Now for a more complicated example, the factorial of a number. For example, the
│ │ │ │ -factorial of 4 is 4 <em> 3 </em> 2 * 1, which equals 24.</p><p>Enter the following code in a file named <code class="inline">tut1.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4291403400-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="4291403400-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4291403400-2">(</span><span class="p" data-group-id="4291403400-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4291403400-3">]</span><span class="p" data-group-id="4291403400-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +factorial of 4 is 4 <em> 3 </em> 2 * 1, which equals 24.</p><p>Enter the following code in a file named <code class="inline">tut1.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7223134645-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="7223134645-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7223134645-2">(</span><span class="p" data-group-id="7223134645-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7223134645-3">]</span><span class="p" data-group-id="7223134645-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="4291403400-4">(</span><span class="mi">1</span><span class="p" data-group-id="4291403400-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="7223134645-4">(</span><span class="mi">1</span><span class="p" data-group-id="7223134645-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="4291403400-5">(</span><span class="n">N</span><span class="p" data-group-id="4291403400-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="4291403400-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4291403400-6">)</span><span class="p">.</span></code></pre><p>So this is a module, called <code class="inline">tut1</code> that contains a function called <code class="inline">fac&gt;</code>, which
│ │ │ │ -takes one argument, <code class="inline">N</code>.</p><p>The first part says that the factorial of 1 is 1.:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="3765987305-1">(</span><span class="mi">1</span><span class="p" data-group-id="3765987305-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="7223134645-5">(</span><span class="n">N</span><span class="p" data-group-id="7223134645-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="7223134645-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7223134645-6">)</span><span class="p">.</span></code></pre><p>So this is a module, called <code class="inline">tut1</code> that contains a function called <code class="inline">fac&gt;</code>, which
│ │ │ │ +takes one argument, <code class="inline">N</code>.</p><p>The first part says that the factorial of 1 is 1.:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="1511043626-1">(</span><span class="mi">1</span><span class="p" data-group-id="1511043626-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="mi">1</span><span class="p">;</span></code></pre><p>Notice that this part ends with a semicolon <code class="inline">;</code> that indicates that there is
│ │ │ │  more of the function <code class="inline">fac&gt;</code> to come.</p><p>The second part says that the factorial of N is N multiplied by the factorial of
│ │ │ │ -N - 1:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="4681649489-1">(</span><span class="n">N</span><span class="p" data-group-id="4681649489-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="4681649489-2">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4681649489-2">)</span><span class="p">.</span></code></pre><p>Notice that this part ends with a <code class="inline">.</code> saying that there are no more parts of
│ │ │ │ -this function.</p><p>Compile the file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="9454826809-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="9454826809-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9454826809-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="9454826809-2">}</span></code></pre><p>And now calculate the factorial of 4.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">6&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">fac</span><span class="p" data-group-id="8846903977-1">(</span><span class="mi">4</span><span class="p" data-group-id="8846903977-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +N - 1:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="0268965989-1">(</span><span class="n">N</span><span class="p" data-group-id="0268965989-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="0268965989-2">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="0268965989-2">)</span><span class="p">.</span></code></pre><p>Notice that this part ends with a <code class="inline">.</code> saying that there are no more parts of
│ │ │ │ +this function.</p><p>Compile the file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="2200057955-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="2200057955-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2200057955-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="2200057955-2">}</span></code></pre><p>And now calculate the factorial of 4.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">6&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">fac</span><span class="p" data-group-id="5107610053-1">(</span><span class="mi">4</span><span class="p" data-group-id="5107610053-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">24</span></code></pre><p>Here the function <code class="inline">fac&gt;</code> in module <code class="inline">tut1</code> is called with argument <code class="inline">4</code>.</p><p>A function can have many arguments. Let us expand the module <code class="inline">tut1</code> with the
│ │ │ │ -function to multiply two numbers:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0137991745-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="0137991745-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0137991745-2">(</span><span class="p" data-group-id="0137991745-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">mult</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0137991745-3">]</span><span class="p" data-group-id="0137991745-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +function to multiply two numbers:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3738523950-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="3738523950-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3738523950-2">(</span><span class="p" data-group-id="3738523950-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">mult</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3738523950-3">]</span><span class="p" data-group-id="3738523950-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="0137991745-4">(</span><span class="mi">1</span><span class="p" data-group-id="0137991745-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="3738523950-4">(</span><span class="mi">1</span><span class="p" data-group-id="3738523950-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="0137991745-5">(</span><span class="n">N</span><span class="p" data-group-id="0137991745-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="0137991745-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="0137991745-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="3738523950-5">(</span><span class="n">N</span><span class="p" data-group-id="3738523950-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="3738523950-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3738523950-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">mult</span><span class="p" data-group-id="0137991745-7">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0137991745-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">mult</span><span class="p" data-group-id="3738523950-7">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3738523950-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span></code></pre><p>Notice that it is also required to expand the <code class="inline">-export</code> line with the
│ │ │ │ -information that there is another function <code class="inline">mult</code> with two arguments.</p><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nf">c</span><span class="p" data-group-id="0748571769-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="0748571769-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0748571769-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="0748571769-2">}</span></code></pre><p>Try out the new function <code class="inline">mult</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">8&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">mult</span><span class="p" data-group-id="4409589551-1">(</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="4409589551-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +information that there is another function <code class="inline">mult</code> with two arguments.</p><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nf">c</span><span class="p" data-group-id="7690070675-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="7690070675-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7690070675-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="7690070675-2">}</span></code></pre><p>Try out the new function <code class="inline">mult</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">8&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">mult</span><span class="p" data-group-id="5883041379-1">(</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5883041379-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">12</span></code></pre><p>In this example the numbers are integers and the arguments in the functions in
│ │ │ │  the code <code class="inline">N</code>, <code class="inline">X</code>, and <code class="inline">Y</code> are called variables. Variables must start with a
│ │ │ │  capital letter (see <a href="../../../lib/../system/doc/html/expressions.xhtml">Variables</a>). Examples of
│ │ │ │  variables are <code class="inline">Number</code>, <code class="inline">ShoeSize</code>, and <code class="inline">Age</code>.</p><h2 id="atoms" class="section-heading">
│ │ │ │    <a href="#atoms" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Atoms</span>
│ │ │ │  </h2>
│ │ │ │  <p>Atom is another data type in Erlang. Atoms start with a small letter (see
│ │ │ │  <a href="../../../lib/../system/doc/html/data_types.xhtml">Atom</a>), for example, <code class="inline">charles</code>, <code class="inline">centimeter</code>, and
│ │ │ │  <code class="inline">inch</code>. Atoms are simply names, nothing else. They are not like variables, which
│ │ │ │  can have a value.</p><p>Enter the next program in a file named <code class="inline">tut2.erl</code>). It can be useful for
│ │ │ │ -converting from inches to centimeters and conversely:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8121576340-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="8121576340-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8121576340-2">(</span><span class="p" data-group-id="8121576340-3">[</span><span class="ss">convert</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8121576340-3">]</span><span class="p" data-group-id="8121576340-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +converting from inches to centimeters and conversely:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8030212073-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="8030212073-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8030212073-2">(</span><span class="p" data-group-id="8030212073-3">[</span><span class="ss">convert</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8030212073-3">]</span><span class="p" data-group-id="8030212073-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">convert</span><span class="p" data-group-id="8121576340-4">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="8121576340-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">convert</span><span class="p" data-group-id="8030212073-4">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="8030212073-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">M</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">convert</span><span class="p" data-group-id="8121576340-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="8121576340-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p">.</span></code></pre><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nf">c</span><span class="p" data-group-id="5747410993-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="5747410993-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5747410993-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut2</span><span class="p" data-group-id="5747410993-2">}</span></code></pre><p>Test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">10&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="1729315329-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="1729315329-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">convert</span><span class="p" data-group-id="8030212073-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="8030212073-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p">.</span></code></pre><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nf">c</span><span class="p" data-group-id="7352613093-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="7352613093-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7352613093-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut2</span><span class="p" data-group-id="7352613093-2">}</span></code></pre><p>Test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">10&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="5728988483-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="5728988483-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mf">1.1811023622047243</span><span class="gp unselectable">
│ │ │ │ -11&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="1729315329-2">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="1729315329-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +11&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="5728988483-2">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="5728988483-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mf">17.78</span></code></pre><p>Notice the introduction of decimals (floating point numbers) without any
│ │ │ │  explanation. Hopefully you can cope with that.</p><p>Let us see what happens if something other than <code class="inline">centimeter</code> or <code class="inline">inch</code> is
│ │ │ │ -entered in the <code class="inline">convert</code> function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">12&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="6058997169-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">miles</span><span class="p" data-group-id="6058997169-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +entered in the <code class="inline">convert</code> function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">12&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="5346477582-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">miles</span><span class="p" data-group-id="5346477582-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no function clause matching tut2:convert(3,miles) (tut2.erl, line 4)</span></code></pre><p>The two parts of the <code class="inline">convert</code> function are called its clauses. As shown,
│ │ │ │  <code class="inline">miles</code> is not part of either of the clauses. The Erlang system cannot <em>match</em>
│ │ │ │  either of the clauses so an error message <code class="inline">function_clause</code> is returned. The
│ │ │ │  shell formats the error message nicely, but the error tuple is saved in the
│ │ │ │ -shell's history list and can be output by the shell command <code class="inline">v/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">13&gt; </span><span class="nf">v</span><span class="p" data-group-id="8303209162-1">(</span><span class="mi">12</span><span class="p" data-group-id="8303209162-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8303209162-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="8303209162-3">{</span><span class="ss">function_clause</span><span class="p">,</span><span class="p" data-group-id="8303209162-4">[</span><span class="p" data-group-id="8303209162-5">{</span><span class="ss">tut2</span><span class="p">,</span><span class="ss">convert</span><span class="p">,</span><span class="w">
│ │ │ │ -                                </span><span class="p" data-group-id="8303209162-6">[</span><span class="mi">3</span><span class="p">,</span><span class="ss">miles</span><span class="p" data-group-id="8303209162-6">]</span><span class="p">,</span><span class="w">
│ │ │ │ -                                </span><span class="p" data-group-id="8303209162-7">[</span><span class="p" data-group-id="8303209162-8">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;tut2.erl&quot;</span><span class="p" data-group-id="8303209162-8">}</span><span class="p">,</span><span class="p" data-group-id="8303209162-9">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="8303209162-9">}</span><span class="p" data-group-id="8303209162-7">]</span><span class="p" data-group-id="8303209162-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="p" data-group-id="8303209162-10">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="w">
│ │ │ │ -                                    </span><span class="p" data-group-id="8303209162-11">[</span><span class="p" data-group-id="8303209162-12">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="8303209162-12">}</span><span class="p">,</span><span class="p" data-group-id="8303209162-13">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">677</span><span class="p" data-group-id="8303209162-13">}</span><span class="p" data-group-id="8303209162-11">]</span><span class="p" data-group-id="8303209162-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="p" data-group-id="8303209162-14">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="8303209162-15">[</span><span class="p" data-group-id="8303209162-16">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="8303209162-16">}</span><span class="p">,</span><span class="p" data-group-id="8303209162-17">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">687</span><span class="p" data-group-id="8303209162-17">}</span><span class="p" data-group-id="8303209162-15">]</span><span class="p" data-group-id="8303209162-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="p" data-group-id="8303209162-18">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="8303209162-19">[</span><span class="p" data-group-id="8303209162-20">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="8303209162-20">}</span><span class="p">,</span><span class="p" data-group-id="8303209162-21">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">642</span><span class="p" data-group-id="8303209162-21">}</span><span class="p" data-group-id="8303209162-19">]</span><span class="p" data-group-id="8303209162-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="p" data-group-id="8303209162-22">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_loop</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ -                                 </span><span class="p" data-group-id="8303209162-23">[</span><span class="p" data-group-id="8303209162-24">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="8303209162-24">}</span><span class="p">,</span><span class="p" data-group-id="8303209162-25">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">627</span><span class="p" data-group-id="8303209162-25">}</span><span class="p" data-group-id="8303209162-23">]</span><span class="p" data-group-id="8303209162-22">}</span><span class="p" data-group-id="8303209162-4">]</span><span class="p" data-group-id="8303209162-3">}</span><span class="p" data-group-id="8303209162-2">}</span></code></pre><h2 id="tuples" class="section-heading">
│ │ │ │ +shell's history list and can be output by the shell command <code class="inline">v/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">13&gt; </span><span class="nf">v</span><span class="p" data-group-id="7092648684-1">(</span><span class="mi">12</span><span class="p" data-group-id="7092648684-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7092648684-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="7092648684-3">{</span><span class="ss">function_clause</span><span class="p">,</span><span class="p" data-group-id="7092648684-4">[</span><span class="p" data-group-id="7092648684-5">{</span><span class="ss">tut2</span><span class="p">,</span><span class="ss">convert</span><span class="p">,</span><span class="w">
│ │ │ │ +                                </span><span class="p" data-group-id="7092648684-6">[</span><span class="mi">3</span><span class="p">,</span><span class="ss">miles</span><span class="p" data-group-id="7092648684-6">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                                </span><span class="p" data-group-id="7092648684-7">[</span><span class="p" data-group-id="7092648684-8">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;tut2.erl&quot;</span><span class="p" data-group-id="7092648684-8">}</span><span class="p">,</span><span class="p" data-group-id="7092648684-9">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7092648684-9">}</span><span class="p" data-group-id="7092648684-7">]</span><span class="p" data-group-id="7092648684-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                          </span><span class="p" data-group-id="7092648684-10">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="w">
│ │ │ │ +                                    </span><span class="p" data-group-id="7092648684-11">[</span><span class="p" data-group-id="7092648684-12">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="7092648684-12">}</span><span class="p">,</span><span class="p" data-group-id="7092648684-13">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">677</span><span class="p" data-group-id="7092648684-13">}</span><span class="p" data-group-id="7092648684-11">]</span><span class="p" data-group-id="7092648684-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                          </span><span class="p" data-group-id="7092648684-14">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="7092648684-15">[</span><span class="p" data-group-id="7092648684-16">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="7092648684-16">}</span><span class="p">,</span><span class="p" data-group-id="7092648684-17">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">687</span><span class="p" data-group-id="7092648684-17">}</span><span class="p" data-group-id="7092648684-15">]</span><span class="p" data-group-id="7092648684-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                          </span><span class="p" data-group-id="7092648684-18">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="7092648684-19">[</span><span class="p" data-group-id="7092648684-20">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="7092648684-20">}</span><span class="p">,</span><span class="p" data-group-id="7092648684-21">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">642</span><span class="p" data-group-id="7092648684-21">}</span><span class="p" data-group-id="7092648684-19">]</span><span class="p" data-group-id="7092648684-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                          </span><span class="p" data-group-id="7092648684-22">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_loop</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ │ +                                 </span><span class="p" data-group-id="7092648684-23">[</span><span class="p" data-group-id="7092648684-24">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="7092648684-24">}</span><span class="p">,</span><span class="p" data-group-id="7092648684-25">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">627</span><span class="p" data-group-id="7092648684-25">}</span><span class="p" data-group-id="7092648684-23">]</span><span class="p" data-group-id="7092648684-22">}</span><span class="p" data-group-id="7092648684-4">]</span><span class="p" data-group-id="7092648684-3">}</span><span class="p" data-group-id="7092648684-2">}</span></code></pre><h2 id="tuples" class="section-heading">
│ │ │ │    <a href="#tuples" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Tuples</span>
│ │ │ │  </h2>
│ │ │ │ -<p>Now the <code class="inline">tut2</code> program is hardly good programming style. Consider:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="5103848842-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="5103848842-1">)</span><span class="p">.</span></code></pre><p>Does this mean that 3 is in inches? Or does it mean that 3 is in centimeters and
│ │ │ │ +<p>Now the <code class="inline">tut2</code> program is hardly good programming style. Consider:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="6298885319-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="6298885319-1">)</span><span class="p">.</span></code></pre><p>Does this mean that 3 is in inches? Or does it mean that 3 is in centimeters and
│ │ │ │  is to be converted to inches? Erlang has a way to group things together to make
│ │ │ │  things more understandable. These are called <em>tuples</em> and are surrounded by
│ │ │ │  curly brackets, <code class="inline">{</code> and <code class="inline">}</code>.</p><p>So, <code class="inline">{inch,3}</code> denotes 3 inches and <code class="inline">{centimeter,5}</code> denotes 5 centimeters. Now
│ │ │ │  let us write a new program that converts centimeters to inches and conversely.
│ │ │ │ -Enter the following code in a file called <code class="inline">tut3.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1320323997-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="1320323997-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1320323997-2">(</span><span class="p" data-group-id="1320323997-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1320323997-3">]</span><span class="p" data-group-id="1320323997-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +Enter the following code in a file called <code class="inline">tut3.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9251286542-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="9251286542-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9251286542-2">(</span><span class="p" data-group-id="9251286542-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9251286542-3">]</span><span class="p" data-group-id="9251286542-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="1320323997-4">(</span><span class="p" data-group-id="1320323997-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1320323997-5">}</span><span class="p" data-group-id="1320323997-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1320323997-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="1320323997-6">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="1320323997-7">(</span><span class="p" data-group-id="1320323997-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1320323997-8">}</span><span class="p" data-group-id="1320323997-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1320323997-9">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="1320323997-9">}</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">14&gt; </span><span class="nf">c</span><span class="p" data-group-id="5855940328-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="5855940328-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5855940328-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut3</span><span class="p" data-group-id="5855940328-2">}</span><span class="gp unselectable">
│ │ │ │ -15&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5855940328-3">(</span><span class="p" data-group-id="5855940328-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="5855940328-4">}</span><span class="p" data-group-id="5855940328-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5855940328-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">12.7</span><span class="p" data-group-id="5855940328-5">}</span><span class="gp unselectable">
│ │ │ │ -16&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5855940328-6">(</span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5855940328-7">(</span><span class="p" data-group-id="5855940328-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="5855940328-8">}</span><span class="p" data-group-id="5855940328-7">)</span><span class="p" data-group-id="5855940328-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5855940328-9">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">5.0</span><span class="p" data-group-id="5855940328-9">}</span></code></pre><p>Notice on line 16 that 5 inches is converted to centimeters and back again and
│ │ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="9251286542-4">(</span><span class="p" data-group-id="9251286542-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="9251286542-5">}</span><span class="p" data-group-id="9251286542-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9251286542-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9251286542-6">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="9251286542-7">(</span><span class="p" data-group-id="9251286542-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9251286542-8">}</span><span class="p" data-group-id="9251286542-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9251286542-9">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9251286542-9">}</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">14&gt; </span><span class="nf">c</span><span class="p" data-group-id="5741295321-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="5741295321-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5741295321-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut3</span><span class="p" data-group-id="5741295321-2">}</span><span class="gp unselectable">
│ │ │ │ +15&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5741295321-3">(</span><span class="p" data-group-id="5741295321-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="5741295321-4">}</span><span class="p" data-group-id="5741295321-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5741295321-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">12.7</span><span class="p" data-group-id="5741295321-5">}</span><span class="gp unselectable">
│ │ │ │ +16&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5741295321-6">(</span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5741295321-7">(</span><span class="p" data-group-id="5741295321-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="5741295321-8">}</span><span class="p" data-group-id="5741295321-7">)</span><span class="p" data-group-id="5741295321-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5741295321-9">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">5.0</span><span class="p" data-group-id="5741295321-9">}</span></code></pre><p>Notice on line 16 that 5 inches is converted to centimeters and back again and
│ │ │ │  reassuringly get back to the original value. That is, the argument to a function
│ │ │ │  can be the result of another function. Consider how line 16 (above) works. The
│ │ │ │  argument given to the function <code class="inline">{inch,5}</code> is first matched against the first
│ │ │ │  head clause of <code class="inline">convert_length</code>, that is, <code class="inline">convert_length({centimeter,X})</code>. It
│ │ │ │  can be seen that <code class="inline">{centimeter,X}</code> does not match <code class="inline">{inch,5}</code> (the head is the bit
│ │ │ │  before the <code class="inline">-&gt;</code>). This having failed, let us try the head of the next clause
│ │ │ │  that is, <code class="inline">convert_length({inch,Y})</code>. This matches, and <code class="inline">Y</code> gets the value 5.</p><p>Tuples can have more than two parts, in fact as many parts as you want, and
│ │ │ │  contain any valid Erlang <em>term</em>. For example, to represent the temperature of
│ │ │ │ -various cities of the world:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8558606885-1">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8558606885-2">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="8558606885-2">}</span><span class="p" data-group-id="8558606885-1">}</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8558606885-3">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8558606885-4">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="8558606885-4">}</span><span class="p" data-group-id="8558606885-3">}</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8558606885-5">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8558606885-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="8558606885-6">}</span><span class="p" data-group-id="8558606885-5">}</span></code></pre><p>Tuples have a fixed number of items in them. Each item in a tuple is called an
│ │ │ │ +various cities of the world:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1046843849-1">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1046843849-2">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="1046843849-2">}</span><span class="p" data-group-id="1046843849-1">}</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1046843849-3">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1046843849-4">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="1046843849-4">}</span><span class="p" data-group-id="1046843849-3">}</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1046843849-5">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1046843849-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="1046843849-6">}</span><span class="p" data-group-id="1046843849-5">}</span></code></pre><p>Tuples have a fixed number of items in them. Each item in a tuple is called an
│ │ │ │  <em>element</em>. In the tuple <code class="inline">{moscow,{c,-10}}</code>, element 1 is <code class="inline">moscow</code> and element 2
│ │ │ │  is <code class="inline">{c,-10}</code>. Here <code class="inline">c</code> represents Celsius and <code class="inline">f</code> Fahrenheit.</p><h2 id="lists" class="section-heading">
│ │ │ │    <a href="#lists" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Lists</span>
│ │ │ │  </h2>
│ │ │ │  <p>Whereas tuples group things together, it is also needed to represent lists of
│ │ │ │  things. Lists in Erlang are surrounded by square brackets, <code class="inline">[</code> and <code class="inline">]</code>. For
│ │ │ │ -example, a list of the temperatures of various cities in the world can be:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6523068259-1">[</span><span class="p" data-group-id="6523068259-2">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="6523068259-3">}</span><span class="p" data-group-id="6523068259-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-4">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-5">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="6523068259-5">}</span><span class="p" data-group-id="6523068259-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-6">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-7">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="6523068259-7">}</span><span class="p" data-group-id="6523068259-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6523068259-8">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="6523068259-9">}</span><span class="p" data-group-id="6523068259-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-10">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6523068259-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="6523068259-11">}</span><span class="p" data-group-id="6523068259-10">}</span><span class="p" data-group-id="6523068259-1">]</span></code></pre><p>Notice that this list was so long that it did not fit on one line. This does not
│ │ │ │ +example, a list of the temperatures of various cities in the world can be:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7929255268-1">[</span><span class="p" data-group-id="7929255268-2">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="7929255268-3">}</span><span class="p" data-group-id="7929255268-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-4">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-5">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="7929255268-5">}</span><span class="p" data-group-id="7929255268-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-6">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-7">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="7929255268-7">}</span><span class="p" data-group-id="7929255268-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7929255268-8">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="7929255268-9">}</span><span class="p" data-group-id="7929255268-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-10">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7929255268-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="7929255268-11">}</span><span class="p" data-group-id="7929255268-10">}</span><span class="p" data-group-id="7929255268-1">]</span></code></pre><p>Notice that this list was so long that it did not fit on one line. This does not
│ │ │ │  matter, Erlang allows line breaks at all &quot;sensible places&quot; but not, for example,
│ │ │ │  in the middle of atoms, integers, and others.</p><p>A useful way of looking at parts of lists, is by using <code class="inline">|</code>. This is best
│ │ │ │ -explained by an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">17&gt; </span><span class="p" data-group-id="9786284737-1">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="n">TheRest</span><span class="p" data-group-id="9786284737-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9786284737-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9786284737-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9786284737-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9786284737-3">]</span><span class="gp unselectable">
│ │ │ │ +explained by an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">17&gt; </span><span class="p" data-group-id="3188326957-1">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="n">TheRest</span><span class="p" data-group-id="3188326957-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3188326957-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3188326957-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3188326957-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3188326957-3">]</span><span class="gp unselectable">
│ │ │ │  18&gt; </span><span class="n">First</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │ │  19&gt; </span><span class="n">TheRest</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9786284737-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9786284737-4">]</span></code></pre><p>To separate the first elements of the list from the rest of the list, <code class="inline">|</code> is
│ │ │ │ -used. <code class="inline">First</code> has got value <code class="inline">1</code> and <code class="inline">TheRest</code> has got the value <code class="inline">[2,3,4,5]</code>.</p><p>Another example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">20&gt; </span><span class="p" data-group-id="0400935065-1">[</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">R</span><span class="p" data-group-id="0400935065-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0400935065-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="0400935065-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0400935065-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="0400935065-3">]</span><span class="gp unselectable">
│ │ │ │ +</span><span class="p" data-group-id="3188326957-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3188326957-4">]</span></code></pre><p>To separate the first elements of the list from the rest of the list, <code class="inline">|</code> is
│ │ │ │ +used. <code class="inline">First</code> has got value <code class="inline">1</code> and <code class="inline">TheRest</code> has got the value <code class="inline">[2,3,4,5]</code>.</p><p>Another example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">20&gt; </span><span class="p" data-group-id="3459578415-1">[</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">R</span><span class="p" data-group-id="3459578415-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3459578415-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="3459578415-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3459578415-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="3459578415-3">]</span><span class="gp unselectable">
│ │ │ │  21&gt; </span><span class="n">E1</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │ │  22&gt; </span><span class="n">E2</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">2</span><span class="gp unselectable">
│ │ │ │  23&gt; </span><span class="n">R</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0400935065-4">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="0400935065-4">]</span></code></pre><p>Here you see the use of <code class="inline">|</code> to get the first two elements from the list. If you
│ │ │ │ +</span><span class="p" data-group-id="3459578415-4">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="3459578415-4">]</span></code></pre><p>Here you see the use of <code class="inline">|</code> to get the first two elements from the list. If you
│ │ │ │  try to get more elements from the list than there are elements in the list, an
│ │ │ │  error is returned. Notice also the special case of the list with no elements,
│ │ │ │ -<code class="inline">[]</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">24&gt; </span><span class="p" data-group-id="6053672868-1">[</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="6053672868-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6053672868-2">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6053672868-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6053672868-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6053672868-3">]</span><span class="gp unselectable">
│ │ │ │ +<code class="inline">[]</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">24&gt; </span><span class="p" data-group-id="3770845582-1">[</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="3770845582-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3770845582-2">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3770845582-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3770845582-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3770845582-3">]</span><span class="gp unselectable">
│ │ │ │  25&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │ │  26&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">2</span><span class="gp unselectable">
│ │ │ │  27&gt; </span><span class="n">C</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6053672868-4">[</span><span class="p" data-group-id="6053672868-4">]</span></code></pre><p>In the previous examples, new variable names are used, instead of reusing the
│ │ │ │ +</span><span class="p" data-group-id="3770845582-4">[</span><span class="p" data-group-id="3770845582-4">]</span></code></pre><p>In the previous examples, new variable names are used, instead of reusing the
│ │ │ │  old ones: <code class="inline">First</code>, <code class="inline">TheRest</code>, <code class="inline">E1</code>, <code class="inline">E2</code>, <code class="inline">R</code>, <code class="inline">A</code>, <code class="inline">B</code>, and <code class="inline">C</code>. The reason for
│ │ │ │  this is that a variable can only be given a value once in its context (scope).
│ │ │ │  More about this later.</p><p>The following example shows how to find the length of a list. Enter the
│ │ │ │ -following code in a file named <code class="inline">tut4.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9985356949-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="9985356949-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +following code in a file named <code class="inline">tut4.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6059713545-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="6059713545-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9985356949-2">(</span><span class="p" data-group-id="9985356949-3">[</span><span class="ss">list_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9985356949-3">]</span><span class="p" data-group-id="9985356949-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6059713545-2">(</span><span class="p" data-group-id="6059713545-3">[</span><span class="ss">list_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6059713545-3">]</span><span class="p" data-group-id="6059713545-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">list_length</span><span class="p" data-group-id="9985356949-4">(</span><span class="p" data-group-id="9985356949-5">[</span><span class="p" data-group-id="9985356949-5">]</span><span class="p" data-group-id="9985356949-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">list_length</span><span class="p" data-group-id="6059713545-4">(</span><span class="p" data-group-id="6059713545-5">[</span><span class="p" data-group-id="6059713545-5">]</span><span class="p" data-group-id="6059713545-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="mi">0</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">list_length</span><span class="p" data-group-id="9985356949-6">(</span><span class="p" data-group-id="9985356949-7">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9985356949-7">]</span><span class="p" data-group-id="9985356949-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="9985356949-8">(</span><span class="n">Rest</span><span class="p" data-group-id="9985356949-8">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">28&gt; </span><span class="nf">c</span><span class="p" data-group-id="0008353444-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="0008353444-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0008353444-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut4</span><span class="p" data-group-id="0008353444-2">}</span><span class="gp unselectable">
│ │ │ │ -29&gt; </span><span class="nc">tut4</span><span class="p">:</span><span class="nf">list_length</span><span class="p" data-group-id="0008353444-3">(</span><span class="p" data-group-id="0008353444-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="0008353444-4">]</span><span class="p" data-group-id="0008353444-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="mi">7</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="3874116951-1">(</span><span class="p" data-group-id="3874116951-2">[</span><span class="p" data-group-id="3874116951-2">]</span><span class="p" data-group-id="3874116951-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="mi">0</span><span class="p">;</span></code></pre><p>The length of an empty list is obviously 0.</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="4918475878-1">(</span><span class="p" data-group-id="4918475878-2">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4918475878-2">]</span><span class="p" data-group-id="4918475878-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="4918475878-3">(</span><span class="n">Rest</span><span class="p" data-group-id="4918475878-3">)</span><span class="p">.</span></code></pre><p>The length of a list with the first element <code class="inline">First</code> and the remaining elements
│ │ │ │ +</span><span class="nf">list_length</span><span class="p" data-group-id="6059713545-6">(</span><span class="p" data-group-id="6059713545-7">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6059713545-7">]</span><span class="p" data-group-id="6059713545-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="6059713545-8">(</span><span class="n">Rest</span><span class="p" data-group-id="6059713545-8">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">28&gt; </span><span class="nf">c</span><span class="p" data-group-id="2350736375-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="2350736375-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2350736375-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut4</span><span class="p" data-group-id="2350736375-2">}</span><span class="gp unselectable">
│ │ │ │ +29&gt; </span><span class="nc">tut4</span><span class="p">:</span><span class="nf">list_length</span><span class="p" data-group-id="2350736375-3">(</span><span class="p" data-group-id="2350736375-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="2350736375-4">]</span><span class="p" data-group-id="2350736375-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="mi">7</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="7091020718-1">(</span><span class="p" data-group-id="7091020718-2">[</span><span class="p" data-group-id="7091020718-2">]</span><span class="p" data-group-id="7091020718-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="mi">0</span><span class="p">;</span></code></pre><p>The length of an empty list is obviously 0.</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="2331507328-1">(</span><span class="p" data-group-id="2331507328-2">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="2331507328-2">]</span><span class="p" data-group-id="2331507328-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="2331507328-3">(</span><span class="n">Rest</span><span class="p" data-group-id="2331507328-3">)</span><span class="p">.</span></code></pre><p>The length of a list with the first element <code class="inline">First</code> and the remaining elements
│ │ │ │  <code class="inline">Rest</code> is 1 + the length of <code class="inline">Rest</code>.</p><p>(Advanced readers only: This is not tail recursive, there is a better way to
│ │ │ │  write this function.)</p><p>In general, tuples are used where &quot;records&quot; or &quot;structs&quot; are used in other
│ │ │ │  languages. Also, lists are used when representing things with varying sizes,
│ │ │ │  that is, where linked lists are used in other languages.</p><p>Erlang does not have a string data type. Instead, strings can be represented by
│ │ │ │  lists of Unicode characters. This implies for example that the list <code class="inline">[97,98,99]</code>
│ │ │ │  is equivalent to <code class="inline">&quot;abc&quot;</code>. The Erlang shell is &quot;clever&quot; and guesses what list you
│ │ │ │ -mean and outputs it in what it thinks is the most appropriate form, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">30&gt; </span><span class="p" data-group-id="1206146430-1">[</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="1206146430-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +mean and outputs it in what it thinks is the most appropriate form, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">30&gt; </span><span class="p" data-group-id="3065767797-1">[</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="3065767797-1">]</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;abc&quot;</span></code></pre><h2 id="maps" class="section-heading">
│ │ │ │    <a href="#maps" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Maps</span>
│ │ │ │  </h2>
│ │ │ │  <p>Maps are a set of key to value associations. These associations are encapsulated
│ │ │ │ -with <code class="inline">#{</code> and <code class="inline">}</code>. To create an association from <code class="inline">&quot;key&quot;</code> to value <code class="inline">42</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="1197359212-1">#{</span><span class="w"> </span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p" data-group-id="1197359212-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1197359212-2">#{</span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="1197359212-2">}</span></code></pre><p>Let us jump straight into the deep end with an example using some interesting
│ │ │ │ +with <code class="inline">#{</code> and <code class="inline">}</code>. To create an association from <code class="inline">&quot;key&quot;</code> to value <code class="inline">42</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="3019160803-1">#{</span><span class="w"> </span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p" data-group-id="3019160803-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3019160803-2">#{</span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="3019160803-2">}</span></code></pre><p>Let us jump straight into the deep end with an example using some interesting
│ │ │ │  features.</p><p>The following example shows how to calculate alpha blending using maps to
│ │ │ │ -reference color and alpha channels. Enter the code in a file named <code class="inline">color.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0017779855-1">(</span><span class="ss">color</span><span class="p" data-group-id="0017779855-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +reference color and alpha channels. Enter the code in a file named <code class="inline">color.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3157110101-1">(</span><span class="ss">color</span><span class="p" data-group-id="3157110101-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0017779855-2">(</span><span class="p" data-group-id="0017779855-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="ss">blend</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0017779855-3">]</span><span class="p" data-group-id="0017779855-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3157110101-2">(</span><span class="p" data-group-id="3157110101-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="ss">blend</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3157110101-3">]</span><span class="p" data-group-id="3157110101-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0017779855-4">(</span><span class="nf">is_channel</span><span class="p" data-group-id="0017779855-5">(</span><span class="n">V</span><span class="p" data-group-id="0017779855-5">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0017779855-6">(</span><span class="nf">is_float</span><span class="p" data-group-id="0017779855-7">(</span><span class="n">V</span><span class="p" data-group-id="0017779855-7">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="0017779855-6">)</span><span class="p" data-group-id="0017779855-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3157110101-4">(</span><span class="nf">is_channel</span><span class="p" data-group-id="3157110101-5">(</span><span class="n">V</span><span class="p" data-group-id="3157110101-5">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3157110101-6">(</span><span class="nf">is_float</span><span class="p" data-group-id="3157110101-7">(</span><span class="n">V</span><span class="p" data-group-id="3157110101-7">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="3157110101-6">)</span><span class="p" data-group-id="3157110101-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">new</span><span class="p" data-group-id="0017779855-8">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="0017779855-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0017779855-9">(</span><span class="n">R</span><span class="p" data-group-id="0017779855-9">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0017779855-10">(</span><span class="n">G</span><span class="p" data-group-id="0017779855-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0017779855-11">(</span><span class="n">B</span><span class="p" data-group-id="0017779855-11">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0017779855-12">(</span><span class="n">A</span><span class="p" data-group-id="0017779855-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0017779855-13">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="0017779855-13">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">blend</span><span class="p" data-group-id="0017779855-14">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0017779855-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">blend</span><span class="p" data-group-id="0017779855-15">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="nf">alpha</span><span class="p" data-group-id="0017779855-16">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0017779855-16">)</span><span class="p" data-group-id="0017779855-15">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">blend</span><span class="p" data-group-id="0017779855-17">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="0017779855-17">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Dst</span><span class="p" data-group-id="0017779855-18">#{</span><span class="w">
│ │ │ │ -        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="0017779855-19">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0017779855-19">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="0017779855-20">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0017779855-20">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="0017779855-21">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0017779855-21">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">new</span><span class="p" data-group-id="3157110101-8">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="3157110101-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="3157110101-9">(</span><span class="n">R</span><span class="p" data-group-id="3157110101-9">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="3157110101-10">(</span><span class="n">G</span><span class="p" data-group-id="3157110101-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="3157110101-11">(</span><span class="n">B</span><span class="p" data-group-id="3157110101-11">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="3157110101-12">(</span><span class="n">A</span><span class="p" data-group-id="3157110101-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3157110101-13">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="3157110101-13">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">blend</span><span class="p" data-group-id="3157110101-14">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="3157110101-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">blend</span><span class="p" data-group-id="3157110101-15">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="nf">alpha</span><span class="p" data-group-id="3157110101-16">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="3157110101-16">)</span><span class="p" data-group-id="3157110101-15">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">blend</span><span class="p" data-group-id="3157110101-17">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="3157110101-17">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Dst</span><span class="p" data-group-id="3157110101-18">#{</span><span class="w">
│ │ │ │ +        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="3157110101-19">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="3157110101-19">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="3157110101-20">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="3157110101-20">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="3157110101-21">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="3157110101-21">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Alpha</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0017779855-18">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">blend</span><span class="p" data-group-id="0017779855-22">(</span><span class="p">_</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0017779855-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Dst</span><span class="p" data-group-id="0017779855-23">#{</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3157110101-18">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">blend</span><span class="p" data-group-id="3157110101-22">(</span><span class="p">_</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="3157110101-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Dst</span><span class="p" data-group-id="3157110101-23">#{</span><span class="w">
│ │ │ │          </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0017779855-23">}</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3157110101-23">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">alpha</span><span class="p" data-group-id="0017779855-24">(</span><span class="p" data-group-id="0017779855-25">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0017779855-26">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="0017779855-26">}</span><span class="p" data-group-id="0017779855-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="0017779855-27">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-27">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">alpha</span><span class="p" data-group-id="3157110101-24">(</span><span class="p" data-group-id="3157110101-25">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3157110101-26">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="3157110101-26">}</span><span class="p" data-group-id="3157110101-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="3157110101-27">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-27">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">red</span><span class="p" data-group-id="0017779855-28">(</span><span class="p" data-group-id="0017779855-29">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-29">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0017779855-30">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="0017779855-30">}</span><span class="p" data-group-id="0017779855-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="0017779855-31">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-31">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">green</span><span class="p" data-group-id="0017779855-32">(</span><span class="p" data-group-id="0017779855-33">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-33">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0017779855-34">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="0017779855-34">}</span><span class="p" data-group-id="0017779855-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="0017779855-35">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-35">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">blue</span><span class="p" data-group-id="0017779855-36">(</span><span class="p" data-group-id="0017779855-37">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-37">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0017779855-38">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="0017779855-38">}</span><span class="p" data-group-id="0017779855-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="0017779855-39">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0017779855-39">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">c</span><span class="p" data-group-id="7970156028-1">(</span><span class="ss">color</span><span class="p" data-group-id="7970156028-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7970156028-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">color</span><span class="p" data-group-id="7970156028-2">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">C1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="7970156028-3">(</span><span class="mf">0.3</span><span class="p">,</span><span class="mf">0.4</span><span class="p">,</span><span class="mf">0.5</span><span class="p">,</span><span class="mf">1.0</span><span class="p" data-group-id="7970156028-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7970156028-4">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="7970156028-4">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">C2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="7970156028-5">(</span><span class="mf">1.0</span><span class="p">,</span><span class="mf">0.8</span><span class="p">,</span><span class="mf">0.1</span><span class="p">,</span><span class="mf">0.3</span><span class="p" data-group-id="7970156028-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7970156028-6">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.1</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.8</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="7970156028-6">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="7970156028-7">(</span><span class="n">C1</span><span class="p">,</span><span class="n">C2</span><span class="p" data-group-id="7970156028-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7970156028-8">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="7970156028-8">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="7970156028-9">(</span><span class="n">C2</span><span class="p">,</span><span class="n">C1</span><span class="p" data-group-id="7970156028-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7970156028-10">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.38</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.52</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.51</span><span class="p" data-group-id="7970156028-10">}</span></code></pre><p>This example warrants some explanation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5591979201-1">(</span><span class="nf">is_channel</span><span class="p" data-group-id="5591979201-2">(</span><span class="n">V</span><span class="p" data-group-id="5591979201-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5591979201-3">(</span><span class="nf">is_float</span><span class="p" data-group-id="5591979201-4">(</span><span class="n">V</span><span class="p" data-group-id="5591979201-4">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="5591979201-3">)</span><span class="p" data-group-id="5591979201-1">)</span><span class="p">.</span></code></pre><p>First a macro <code class="inline">is_channel</code> is defined to help with the guard tests. This is only
│ │ │ │ +</span><span class="nf">red</span><span class="p" data-group-id="3157110101-28">(</span><span class="p" data-group-id="3157110101-29">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-29">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3157110101-30">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="3157110101-30">}</span><span class="p" data-group-id="3157110101-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="3157110101-31">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-31">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">green</span><span class="p" data-group-id="3157110101-32">(</span><span class="p" data-group-id="3157110101-33">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-33">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3157110101-34">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="3157110101-34">}</span><span class="p" data-group-id="3157110101-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="3157110101-35">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-35">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">blue</span><span class="p" data-group-id="3157110101-36">(</span><span class="p" data-group-id="3157110101-37">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-37">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3157110101-38">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="3157110101-38">}</span><span class="p" data-group-id="3157110101-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="3157110101-39">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3157110101-39">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">c</span><span class="p" data-group-id="9632009748-1">(</span><span class="ss">color</span><span class="p" data-group-id="9632009748-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9632009748-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">color</span><span class="p" data-group-id="9632009748-2">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="n">C1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="9632009748-3">(</span><span class="mf">0.3</span><span class="p">,</span><span class="mf">0.4</span><span class="p">,</span><span class="mf">0.5</span><span class="p">,</span><span class="mf">1.0</span><span class="p" data-group-id="9632009748-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9632009748-4">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="9632009748-4">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="n">C2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="9632009748-5">(</span><span class="mf">1.0</span><span class="p">,</span><span class="mf">0.8</span><span class="p">,</span><span class="mf">0.1</span><span class="p">,</span><span class="mf">0.3</span><span class="p" data-group-id="9632009748-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9632009748-6">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.1</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.8</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="9632009748-6">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="9632009748-7">(</span><span class="n">C1</span><span class="p">,</span><span class="n">C2</span><span class="p" data-group-id="9632009748-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9632009748-8">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="9632009748-8">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="9632009748-9">(</span><span class="n">C2</span><span class="p">,</span><span class="n">C1</span><span class="p" data-group-id="9632009748-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9632009748-10">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.38</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.52</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.51</span><span class="p" data-group-id="9632009748-10">}</span></code></pre><p>This example warrants some explanation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5286013622-1">(</span><span class="nf">is_channel</span><span class="p" data-group-id="5286013622-2">(</span><span class="n">V</span><span class="p" data-group-id="5286013622-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5286013622-3">(</span><span class="nf">is_float</span><span class="p" data-group-id="5286013622-4">(</span><span class="n">V</span><span class="p" data-group-id="5286013622-4">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="5286013622-3">)</span><span class="p" data-group-id="5286013622-1">)</span><span class="p">.</span></code></pre><p>First a macro <code class="inline">is_channel</code> is defined to help with the guard tests. This is only
│ │ │ │  here for convenience and to reduce syntax cluttering. For more information about
│ │ │ │ -macros, see <a href="../../../lib/../system/doc/html/macros.xhtml">The Preprocessor</a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="9445235595-1">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="9445235595-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9445235595-2">(</span><span class="n">R</span><span class="p" data-group-id="9445235595-2">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9445235595-3">(</span><span class="n">G</span><span class="p" data-group-id="9445235595-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9445235595-4">(</span><span class="n">B</span><span class="p" data-group-id="9445235595-4">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9445235595-5">(</span><span class="n">A</span><span class="p" data-group-id="9445235595-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9445235595-6">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="9445235595-6">}</span><span class="p">.</span></code></pre><p>The function <code class="inline">new/4</code> creates a new map term and lets the keys <code class="inline">red</code>, <code class="inline">green</code>,
│ │ │ │ +macros, see <a href="../../../lib/../system/doc/html/macros.xhtml">The Preprocessor</a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="0003991044-1">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="0003991044-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0003991044-2">(</span><span class="n">R</span><span class="p" data-group-id="0003991044-2">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0003991044-3">(</span><span class="n">G</span><span class="p" data-group-id="0003991044-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0003991044-4">(</span><span class="n">B</span><span class="p" data-group-id="0003991044-4">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="0003991044-5">(</span><span class="n">A</span><span class="p" data-group-id="0003991044-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0003991044-6">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="0003991044-6">}</span><span class="p">.</span></code></pre><p>The function <code class="inline">new/4</code> creates a new map term and lets the keys <code class="inline">red</code>, <code class="inline">green</code>,
│ │ │ │  <code class="inline">blue</code>, and <code class="inline">alpha</code> be associated with an initial value. In this case, only
│ │ │ │  float values between and including 0.0 and 1.0 are allowed, as ensured by the
│ │ │ │  <code class="inline">?is_channel/1</code> macro for each argument. Only the <code class="inline">=&gt;</code> operator is allowed when
│ │ │ │  creating a new map.</p><p>By calling <code class="inline">blend/2</code> on any color term created by <code class="inline">new/4</code>, the resulting color
│ │ │ │ -can be calculated as determined by the two map terms.</p><p>The first thing <code class="inline">blend/2</code> does is to calculate the resulting alpha channel:</p><pre><code class="makeup erlang" translate="no"><span class="nf">alpha</span><span class="p" data-group-id="5241488383-1">(</span><span class="p" data-group-id="5241488383-2">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="5241488383-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5241488383-3">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="5241488383-3">}</span><span class="p" data-group-id="5241488383-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="5241488383-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="5241488383-4">)</span><span class="p">.</span></code></pre><p>The value associated with key <code class="inline">alpha</code> is fetched for both arguments using the
│ │ │ │ +can be calculated as determined by the two map terms.</p><p>The first thing <code class="inline">blend/2</code> does is to calculate the resulting alpha channel:</p><pre><code class="makeup erlang" translate="no"><span class="nf">alpha</span><span class="p" data-group-id="2141385986-1">(</span><span class="p" data-group-id="2141385986-2">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2141385986-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2141385986-3">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="2141385986-3">}</span><span class="p" data-group-id="2141385986-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="2141385986-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2141385986-4">)</span><span class="p">.</span></code></pre><p>The value associated with key <code class="inline">alpha</code> is fetched for both arguments using the
│ │ │ │  <code class="inline">:=</code> operator. The other keys in the map are ignored, only the key <code class="inline">alpha</code> is
│ │ │ │ -required and checked for.</p><p>This is also the case for functions <code class="inline">red/2</code>, <code class="inline">blue/2</code>, and <code class="inline">green/2</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">red</span><span class="p" data-group-id="0955794014-1">(</span><span class="p" data-group-id="0955794014-2">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0955794014-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0955794014-3">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="0955794014-3">}</span><span class="p" data-group-id="0955794014-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="0955794014-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="0955794014-4">)</span><span class="p">.</span></code></pre><p>The difference here is that a check is made for two keys in each map argument.
│ │ │ │ -The other keys are ignored.</p><p>Finally, let us return the resulting color in <code class="inline">blend/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">blend</span><span class="p" data-group-id="0183337296-1">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="0183337296-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Dst</span><span class="p" data-group-id="0183337296-2">#{</span><span class="w">
│ │ │ │ -        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="0183337296-3">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0183337296-3">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="0183337296-4">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0183337296-4">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="0183337296-5">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="0183337296-5">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ +required and checked for.</p><p>This is also the case for functions <code class="inline">red/2</code>, <code class="inline">blue/2</code>, and <code class="inline">green/2</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">red</span><span class="p" data-group-id="3388218790-1">(</span><span class="p" data-group-id="3388218790-2">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3388218790-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3388218790-3">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="3388218790-3">}</span><span class="p" data-group-id="3388218790-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="3388218790-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3388218790-4">)</span><span class="p">.</span></code></pre><p>The difference here is that a check is made for two keys in each map argument.
│ │ │ │ +The other keys are ignored.</p><p>Finally, let us return the resulting color in <code class="inline">blend/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">blend</span><span class="p" data-group-id="9995027777-1">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="9995027777-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Dst</span><span class="p" data-group-id="9995027777-2">#{</span><span class="w">
│ │ │ │ +        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="9995027777-3">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9995027777-3">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="9995027777-4">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9995027777-4">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="9995027777-5">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9995027777-5">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Alpha</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0183337296-2">}</span><span class="p">;</span></code></pre><p>The <code class="inline">Dst</code> map is updated with new channel values. The syntax for updating an
│ │ │ │ +    </span><span class="p" data-group-id="9995027777-2">}</span><span class="p">;</span></code></pre><p>The <code class="inline">Dst</code> map is updated with new channel values. The syntax for updating an
│ │ │ │  existing key with a new value is with the <code class="inline">:=</code> operator.</p><h2 id="standard-modules-and-manual-pages" class="section-heading">
│ │ │ │    <a href="#standard-modules-and-manual-pages" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Standard Modules and Manual Pages</span>
│ │ │ │  </h2>
│ │ │ │  <p>Erlang has many standard modules to help you do things. For example, the module
│ │ │ │ @@ -347,24 +347,24 @@
│ │ │ │    <a href="#writing-output-to-a-terminal" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Writing Output to a Terminal</span>
│ │ │ │  </h2>
│ │ │ │  <p>It is nice to be able to do formatted output in examples, so the next example
│ │ │ │  shows a simple way to use the <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function. Like all other exported
│ │ │ │ -functions, you can test the <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">31&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5950559052-1">(</span><span class="s">&quot;hello world</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5950559052-2">[</span><span class="p" data-group-id="5950559052-2">]</span><span class="p" data-group-id="5950559052-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +functions, you can test the <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">31&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5120336535-1">(</span><span class="s">&quot;hello world</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5120336535-2">[</span><span class="p" data-group-id="5120336535-2">]</span><span class="p" data-group-id="5120336535-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="w"> </span><span class="ss">world</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -32&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5950559052-3">(</span><span class="s">&quot;this outputs one Erlang term: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5950559052-4">[</span><span class="ss">hello</span><span class="p" data-group-id="5950559052-4">]</span><span class="p" data-group-id="5950559052-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +32&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5120336535-3">(</span><span class="s">&quot;this outputs one Erlang term: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5120336535-4">[</span><span class="ss">hello</span><span class="p" data-group-id="5120336535-4">]</span><span class="p" data-group-id="5120336535-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">this</span><span class="w"> </span><span class="ss">outputs</span><span class="w"> </span><span class="ss">one</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="nc">term</span><span class="p">:</span><span class="w"> </span><span class="ss">hello</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -33&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5950559052-5">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5950559052-6">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="5950559052-6">]</span><span class="p" data-group-id="5950559052-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +33&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5120336535-5">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5120336535-6">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="5120336535-6">]</span><span class="p" data-group-id="5120336535-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">this</span><span class="w"> </span><span class="ss">outputs</span><span class="w"> </span><span class="ss">two</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="nc">terms</span><span class="p">:</span><span class="w"> </span><span class="ss">helloworld</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -34&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5950559052-7">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5950559052-8">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="5950559052-8">]</span><span class="p" data-group-id="5950559052-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +34&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5120336535-7">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5120336535-8">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="5120336535-8">]</span><span class="p" data-group-id="5120336535-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">this</span><span class="w"> </span><span class="ss">outputs</span><span class="w"> </span><span class="ss">two</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="nc">terms</span><span class="p">:</span><span class="w"> </span><span class="ss">hello</span><span class="w"> </span><span class="ss">world</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>The function <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> (that is, <code class="inline">format</code> with two arguments) takes two lists.
│ │ │ │  The first one is nearly always a list written between <code class="inline">&quot; &quot;</code>. This list is printed
│ │ │ │  out as it is, except that each <code class="inline">~w</code> is replaced by a term taken in order from the
│ │ │ │  second list. Each ~n is replaced by a new line. The <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function
│ │ │ │  itself returns the atom <code class="inline">ok</code> if everything goes as planned. Like other functions
│ │ │ │  in Erlang, it crashes if an error occurs. This is not a fault in Erlang, it is a
│ │ │ │ @@ -378,34 +378,34 @@
│ │ │ │    <span class="text">A Larger Example</span>
│ │ │ │  </h2>
│ │ │ │  <p>Now for a larger example to consolidate what you have learnt so far. Assume that
│ │ │ │  you have a list of temperature readings from a number of cities in the world.
│ │ │ │  Some of them are in Celsius and some in Fahrenheit (as in the previous list).
│ │ │ │  First let us convert them all to Celsius, then let us print the data neatly.</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% This module is in file tut5.erl</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1194236018-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="1194236018-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1194236018-2">(</span><span class="p" data-group-id="1194236018-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1194236018-3">]</span><span class="p" data-group-id="1194236018-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2989481616-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="2989481616-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2989481616-2">(</span><span class="p" data-group-id="2989481616-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2989481616-3">]</span><span class="p" data-group-id="2989481616-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% Only this function is exported</span><span class="w">
│ │ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="1194236018-4">(</span><span class="p" data-group-id="1194236018-5">[</span><span class="p" data-group-id="1194236018-5">]</span><span class="p" data-group-id="1194236018-4">)</span><span class="p">-&gt;</span><span class="w">                        </span><span class="c1">% No output for an empty list</span><span class="w">
│ │ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="2989481616-4">(</span><span class="p" data-group-id="2989481616-5">[</span><span class="p" data-group-id="2989481616-5">]</span><span class="p" data-group-id="2989481616-4">)</span><span class="p">-&gt;</span><span class="w">                        </span><span class="c1">% No output for an empty list</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="1194236018-6">(</span><span class="p" data-group-id="1194236018-7">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="1194236018-7">]</span><span class="p" data-group-id="1194236018-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="1194236018-8">(</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="1194236018-9">(</span><span class="n">City</span><span class="p" data-group-id="1194236018-9">)</span><span class="p" data-group-id="1194236018-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">format_temps</span><span class="p" data-group-id="1194236018-10">(</span><span class="n">Rest</span><span class="p" data-group-id="1194236018-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="1194236018-11">(</span><span class="p" data-group-id="1194236018-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194236018-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1194236018-13">}</span><span class="p" data-group-id="1194236018-12">}</span><span class="p" data-group-id="1194236018-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% No conversion needed</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1194236018-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194236018-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1194236018-15">}</span><span class="p" data-group-id="1194236018-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="1194236018-16">(</span><span class="p" data-group-id="1194236018-17">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194236018-18">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1194236018-18">}</span><span class="p" data-group-id="1194236018-17">}</span><span class="p" data-group-id="1194236018-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Do the conversion</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1194236018-19">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194236018-20">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194236018-21">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="1194236018-21">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="1194236018-20">}</span><span class="p" data-group-id="1194236018-19">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="1194236018-22">(</span><span class="p" data-group-id="1194236018-23">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194236018-24">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1194236018-24">}</span><span class="p" data-group-id="1194236018-23">}</span><span class="p" data-group-id="1194236018-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1194236018-25">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194236018-26">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1194236018-26">]</span><span class="p" data-group-id="1194236018-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">35&gt; </span><span class="nf">c</span><span class="p" data-group-id="9792789550-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="9792789550-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9792789550-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut5</span><span class="p" data-group-id="9792789550-2">}</span><span class="gp unselectable">
│ │ │ │ -36&gt; </span><span class="nc">tut5</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="9792789550-3">(</span><span class="p" data-group-id="9792789550-4">[</span><span class="p" data-group-id="9792789550-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="9792789550-6">}</span><span class="p" data-group-id="9792789550-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="9792789550-8">}</span><span class="p" data-group-id="9792789550-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9792789550-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="9792789550-10">}</span><span class="p" data-group-id="9792789550-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="9792789550-12">}</span><span class="p" data-group-id="9792789550-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9792789550-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="9792789550-14">}</span><span class="p" data-group-id="9792789550-13">}</span><span class="p" data-group-id="9792789550-4">]</span><span class="p" data-group-id="9792789550-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="2989481616-6">(</span><span class="p" data-group-id="2989481616-7">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="2989481616-7">]</span><span class="p" data-group-id="2989481616-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="2989481616-8">(</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="2989481616-9">(</span><span class="n">City</span><span class="p" data-group-id="2989481616-9">)</span><span class="p" data-group-id="2989481616-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">format_temps</span><span class="p" data-group-id="2989481616-10">(</span><span class="n">Rest</span><span class="p" data-group-id="2989481616-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="2989481616-11">(</span><span class="p" data-group-id="2989481616-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2989481616-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2989481616-13">}</span><span class="p" data-group-id="2989481616-12">}</span><span class="p" data-group-id="2989481616-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% No conversion needed</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2989481616-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2989481616-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2989481616-15">}</span><span class="p" data-group-id="2989481616-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="2989481616-16">(</span><span class="p" data-group-id="2989481616-17">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2989481616-18">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2989481616-18">}</span><span class="p" data-group-id="2989481616-17">}</span><span class="p" data-group-id="2989481616-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Do the conversion</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2989481616-19">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2989481616-20">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2989481616-21">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="2989481616-21">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="2989481616-20">}</span><span class="p" data-group-id="2989481616-19">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="2989481616-22">(</span><span class="p" data-group-id="2989481616-23">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2989481616-24">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2989481616-24">}</span><span class="p" data-group-id="2989481616-23">}</span><span class="p" data-group-id="2989481616-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2989481616-25">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2989481616-26">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2989481616-26">]</span><span class="p" data-group-id="2989481616-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">35&gt; </span><span class="nf">c</span><span class="p" data-group-id="3031666282-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="3031666282-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3031666282-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut5</span><span class="p" data-group-id="3031666282-2">}</span><span class="gp unselectable">
│ │ │ │ +36&gt; </span><span class="nc">tut5</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="3031666282-3">(</span><span class="p" data-group-id="3031666282-4">[</span><span class="p" data-group-id="3031666282-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="3031666282-6">}</span><span class="p" data-group-id="3031666282-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="3031666282-8">}</span><span class="p" data-group-id="3031666282-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3031666282-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="3031666282-10">}</span><span class="p" data-group-id="3031666282-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="3031666282-12">}</span><span class="p" data-group-id="3031666282-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3031666282-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="3031666282-14">}</span><span class="p" data-group-id="3031666282-13">}</span><span class="p" data-group-id="3031666282-4">]</span><span class="p" data-group-id="3031666282-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="o">-</span><span class="mi">4</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>Before looking at how this program works, notice that a few comments are added
│ │ │ │  to the code. A comment starts with a %-character and goes on to the end of the
│ │ │ │ @@ -433,28 +433,28 @@
│ │ │ │    <a href="#matching-guards-and-scope-of-variables" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Matching, Guards, and Scope of Variables</span>
│ │ │ │  </h2>
│ │ │ │  <p>It can be useful to find the maximum and minimum temperature in lists like this.
│ │ │ │  Before extending the program to do this, let us look at functions for finding
│ │ │ │ -the maximum value of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7665657258-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="7665657258-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7665657258-2">(</span><span class="p" data-group-id="7665657258-3">[</span><span class="ss">list_max</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7665657258-3">]</span><span class="p" data-group-id="7665657258-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +the maximum value of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5455638105-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="5455638105-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5455638105-2">(</span><span class="p" data-group-id="5455638105-3">[</span><span class="ss">list_max</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5455638105-3">]</span><span class="p" data-group-id="5455638105-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="7665657258-4">(</span><span class="p" data-group-id="7665657258-5">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="7665657258-5">]</span><span class="p" data-group-id="7665657258-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="nf">list_max</span><span class="p" data-group-id="7665657258-6">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="7665657258-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="5455638105-4">(</span><span class="p" data-group-id="5455638105-5">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="5455638105-5">]</span><span class="p" data-group-id="5455638105-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="nf">list_max</span><span class="p" data-group-id="5455638105-6">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="5455638105-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="7665657258-7">(</span><span class="p" data-group-id="7665657258-8">[</span><span class="p" data-group-id="7665657258-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="7665657258-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="5455638105-7">(</span><span class="p" data-group-id="5455638105-8">[</span><span class="p" data-group-id="5455638105-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="5455638105-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Res</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="7665657258-9">(</span><span class="p" data-group-id="7665657258-10">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="7665657258-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="7665657258-9">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">list_max</span><span class="p" data-group-id="7665657258-11">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="7665657258-11">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="7665657258-12">(</span><span class="p" data-group-id="7665657258-13">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="7665657258-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="7665657258-12">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">list_max</span><span class="p" data-group-id="7665657258-14">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="7665657258-14">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">37&gt; </span><span class="nf">c</span><span class="p" data-group-id="2238245657-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="2238245657-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2238245657-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut6</span><span class="p" data-group-id="2238245657-2">}</span><span class="gp unselectable">
│ │ │ │ -38&gt; </span><span class="nc">tut6</span><span class="p">:</span><span class="nf">list_max</span><span class="p" data-group-id="2238245657-3">(</span><span class="p" data-group-id="2238245657-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2238245657-4">]</span><span class="p" data-group-id="2238245657-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="5455638105-9">(</span><span class="p" data-group-id="5455638105-10">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="5455638105-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="5455638105-9">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">list_max</span><span class="p" data-group-id="5455638105-11">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="5455638105-11">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="5455638105-12">(</span><span class="p" data-group-id="5455638105-13">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="5455638105-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="5455638105-12">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">list_max</span><span class="p" data-group-id="5455638105-14">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="5455638105-14">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">37&gt; </span><span class="nf">c</span><span class="p" data-group-id="6685368170-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="6685368170-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6685368170-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut6</span><span class="p" data-group-id="6685368170-2">}</span><span class="gp unselectable">
│ │ │ │ +38&gt; </span><span class="nc">tut6</span><span class="p">:</span><span class="nf">list_max</span><span class="p" data-group-id="6685368170-3">(</span><span class="p" data-group-id="6685368170-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="6685368170-4">]</span><span class="p" data-group-id="6685368170-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">7</span></code></pre><p>First notice that two functions have the same name, <code class="inline">list_max</code>. However, each of
│ │ │ │  these takes a different number of arguments (parameters). In Erlang these are
│ │ │ │  regarded as completely different functions. Where you need to distinguish
│ │ │ │  between these functions, you write Name/Arity, where Name is the function name
│ │ │ │  and Arity is the number of arguments, in this case <code class="inline">list_max/1</code> and
│ │ │ │  <code class="inline">list_max/2</code>.</p><p>In this example you walk through a list &quot;carrying&quot; a value, in this case
│ │ │ │  <code class="inline">Result_so_far</code>. <code class="inline">list_max/1</code> simply assumes that the max value of the list is
│ │ │ │ @@ -483,180 +483,180 @@
│ │ │ │  </span><span class="mi">5</span><span class="gp unselectable">
│ │ │ │  40&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no match of right hand side value 6</span><span class="gp unselectable">
│ │ │ │  41&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no match of right hand side value 6</span><span class="gp unselectable">
│ │ │ │  42&gt; </span><span class="n">N</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">6</span></code></pre><p>The use of the match operator is particularly useful for pulling apart Erlang
│ │ │ │ -terms and creating new ones.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">43&gt; </span><span class="p" data-group-id="7844155839-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7844155839-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7844155839-2">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7844155839-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="7844155839-3">}</span><span class="p" data-group-id="7844155839-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7844155839-4">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="7844155839-5">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="7844155839-5">}</span><span class="p" data-group-id="7844155839-4">}</span><span class="gp unselectable">
│ │ │ │ +terms and creating new ones.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">43&gt; </span><span class="p" data-group-id="0249002346-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0249002346-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0249002346-2">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0249002346-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="0249002346-3">}</span><span class="p" data-group-id="0249002346-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0249002346-4">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="0249002346-5">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="0249002346-5">}</span><span class="p" data-group-id="0249002346-4">}</span><span class="gp unselectable">
│ │ │ │  44&gt; </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">paris</span><span class="gp unselectable">
│ │ │ │  45&gt; </span><span class="n">Y</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7844155839-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="7844155839-6">}</span></code></pre><p>Here <code class="inline">X</code> gets the value <code class="inline">paris</code> and <code class="inline">Y</code> the value <code class="inline">{f,28}</code>.</p><p>If you try to do the same again with another city, an error is returned:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">46&gt; </span><span class="p" data-group-id="9332734342-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9332734342-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9332734342-2">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9332734342-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="9332734342-3">}</span><span class="p" data-group-id="9332734342-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0249002346-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="0249002346-6">}</span></code></pre><p>Here <code class="inline">X</code> gets the value <code class="inline">paris</code> and <code class="inline">Y</code> the value <code class="inline">{f,28}</code>.</p><p>If you try to do the same again with another city, an error is returned:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">46&gt; </span><span class="p" data-group-id="6557750460-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6557750460-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6557750460-2">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6557750460-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="6557750460-3">}</span><span class="p" data-group-id="6557750460-2">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no match of right hand side value {london,{f,36}}</span></code></pre><p>Variables can also be used to improve the readability of programs. For example,
│ │ │ │ -in function <code class="inline">list_max/2</code> above, you can write:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_max</span><span class="p" data-group-id="1061376607-1">(</span><span class="p" data-group-id="1061376607-2">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="1061376607-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="1061376607-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +in function <code class="inline">list_max/2</code> above, you can write:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_max</span><span class="p" data-group-id="7893675146-1">(</span><span class="p" data-group-id="7893675146-2">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="7893675146-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="7893675146-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">New_result_far</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Head</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">list_max</span><span class="p" data-group-id="1061376607-3">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">New_result_far</span><span class="p" data-group-id="1061376607-3">)</span><span class="p">;</span></code></pre><p>This is possibly a little clearer.</p><h2 id="more-about-lists" class="section-heading">
│ │ │ │ +    </span><span class="nf">list_max</span><span class="p" data-group-id="7893675146-3">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">New_result_far</span><span class="p" data-group-id="7893675146-3">)</span><span class="p">;</span></code></pre><p>This is possibly a little clearer.</p><h2 id="more-about-lists" class="section-heading">
│ │ │ │    <a href="#more-about-lists" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">More About Lists</span>
│ │ │ │  </h2>
│ │ │ │ -<p>Remember that the <code class="inline">|</code> operator can be used to get the head of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">47&gt; </span><span class="p" data-group-id="7017981827-1">[</span><span class="n">M1</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="7017981827-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7017981827-2">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="ss">rome</span><span class="p" data-group-id="7017981827-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7017981827-3">[</span><span class="ss">paris</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="7017981827-3">]</span><span class="gp unselectable">
│ │ │ │ +<p>Remember that the <code class="inline">|</code> operator can be used to get the head of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">47&gt; </span><span class="p" data-group-id="6287167586-1">[</span><span class="n">M1</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="6287167586-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6287167586-2">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="ss">rome</span><span class="p" data-group-id="6287167586-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6287167586-3">[</span><span class="ss">paris</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="6287167586-3">]</span><span class="gp unselectable">
│ │ │ │  48&gt; </span><span class="n">M1</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">paris</span><span class="gp unselectable">
│ │ │ │  49&gt; </span><span class="n">T1</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7017981827-4">[</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="7017981827-4">]</span></code></pre><p>The <code class="inline">|</code> operator can also be used to add a head to a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">50&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3757404688-1">[</span><span class="ss">madrid</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="3757404688-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3757404688-2">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="3757404688-2">]</span><span class="gp unselectable">
│ │ │ │ +</span><span class="p" data-group-id="6287167586-4">[</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="6287167586-4">]</span></code></pre><p>The <code class="inline">|</code> operator can also be used to add a head to a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">50&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4584460327-1">[</span><span class="ss">madrid</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="4584460327-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4584460327-2">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="4584460327-2">]</span><span class="gp unselectable">
│ │ │ │  51&gt; </span><span class="n">L1</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3757404688-3">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="3757404688-3">]</span></code></pre><p>Now an example of this when working with lists - reversing the order of a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3811644483-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="3811644483-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4584460327-3">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="4584460327-3">]</span></code></pre><p>Now an example of this when working with lists - reversing the order of a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6853372225-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="6853372225-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3811644483-2">(</span><span class="p" data-group-id="3811644483-3">[</span><span class="ss">reverse</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3811644483-3">]</span><span class="p" data-group-id="3811644483-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6853372225-2">(</span><span class="p" data-group-id="6853372225-3">[</span><span class="ss">reverse</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6853372225-3">]</span><span class="p" data-group-id="6853372225-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="3811644483-4">(</span><span class="n">List</span><span class="p" data-group-id="3811644483-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="3811644483-5">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3811644483-6">[</span><span class="p" data-group-id="3811644483-6">]</span><span class="p" data-group-id="3811644483-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="6853372225-4">(</span><span class="n">List</span><span class="p" data-group-id="6853372225-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="6853372225-5">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6853372225-6">[</span><span class="p" data-group-id="6853372225-6">]</span><span class="p" data-group-id="6853372225-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="3811644483-7">(</span><span class="p" data-group-id="3811644483-8">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="3811644483-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="3811644483-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="3811644483-9">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3811644483-10">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="3811644483-10">]</span><span class="p" data-group-id="3811644483-9">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="3811644483-11">(</span><span class="p" data-group-id="3811644483-12">[</span><span class="p" data-group-id="3811644483-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="3811644483-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Reversed_List</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">52&gt; </span><span class="nf">c</span><span class="p" data-group-id="8735811660-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="8735811660-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8735811660-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut8</span><span class="p" data-group-id="8735811660-2">}</span><span class="gp unselectable">
│ │ │ │ -53&gt; </span><span class="nc">tut8</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="8735811660-3">(</span><span class="p" data-group-id="8735811660-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8735811660-4">]</span><span class="p" data-group-id="8735811660-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8735811660-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8735811660-5">]</span></code></pre><p>Consider how <code class="inline">Reversed_List</code> is built. It starts as [], then successively the
│ │ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="6853372225-7">(</span><span class="p" data-group-id="6853372225-8">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6853372225-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="6853372225-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="6853372225-9">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6853372225-10">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="6853372225-10">]</span><span class="p" data-group-id="6853372225-9">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="6853372225-11">(</span><span class="p" data-group-id="6853372225-12">[</span><span class="p" data-group-id="6853372225-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="6853372225-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Reversed_List</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">52&gt; </span><span class="nf">c</span><span class="p" data-group-id="1325522487-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="1325522487-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1325522487-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut8</span><span class="p" data-group-id="1325522487-2">}</span><span class="gp unselectable">
│ │ │ │ +53&gt; </span><span class="nc">tut8</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="1325522487-3">(</span><span class="p" data-group-id="1325522487-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1325522487-4">]</span><span class="p" data-group-id="1325522487-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1325522487-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="1325522487-5">]</span></code></pre><p>Consider how <code class="inline">Reversed_List</code> is built. It starts as [], then successively the
│ │ │ │  heads are taken off of the list to be reversed and added to the the
│ │ │ │ -<code class="inline">Reversed_List</code>, as shown in the following:</p><pre><code class="makeup erlang" translate="no"><span class="nf">reverse</span><span class="p" data-group-id="2857078527-1">(</span><span class="p" data-group-id="2857078527-2">[</span><span class="mi">1</span><span class="p">|</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2857078527-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2857078527-3">[</span><span class="p" data-group-id="2857078527-3">]</span><span class="p" data-group-id="2857078527-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="2857078527-4">(</span><span class="p" data-group-id="2857078527-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2857078527-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2857078527-6">[</span><span class="mi">1</span><span class="p">|</span><span class="p" data-group-id="2857078527-7">[</span><span class="p" data-group-id="2857078527-7">]</span><span class="p" data-group-id="2857078527-6">]</span><span class="p" data-group-id="2857078527-4">)</span><span class="w">
│ │ │ │ +<code class="inline">Reversed_List</code>, as shown in the following:</p><pre><code class="makeup erlang" translate="no"><span class="nf">reverse</span><span class="p" data-group-id="0050984556-1">(</span><span class="p" data-group-id="0050984556-2">[</span><span class="mi">1</span><span class="p">|</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0050984556-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050984556-3">[</span><span class="p" data-group-id="0050984556-3">]</span><span class="p" data-group-id="0050984556-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="0050984556-4">(</span><span class="p" data-group-id="0050984556-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0050984556-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050984556-6">[</span><span class="mi">1</span><span class="p">|</span><span class="p" data-group-id="0050984556-7">[</span><span class="p" data-group-id="0050984556-7">]</span><span class="p" data-group-id="0050984556-6">]</span><span class="p" data-group-id="0050984556-4">)</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="2857078527-8">(</span><span class="p" data-group-id="2857078527-9">[</span><span class="mi">2</span><span class="p">|</span><span class="mi">3</span><span class="p" data-group-id="2857078527-9">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2857078527-10">[</span><span class="mi">1</span><span class="p" data-group-id="2857078527-10">]</span><span class="p" data-group-id="2857078527-8">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="2857078527-11">(</span><span class="p" data-group-id="2857078527-12">[</span><span class="mi">3</span><span class="p" data-group-id="2857078527-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2857078527-13">[</span><span class="mi">2</span><span class="p">|</span><span class="p" data-group-id="2857078527-14">[</span><span class="mi">1</span><span class="p" data-group-id="2857078527-14">]</span><span class="p">)</span><span class="w">
│ │ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="0050984556-8">(</span><span class="p" data-group-id="0050984556-9">[</span><span class="mi">2</span><span class="p">|</span><span class="mi">3</span><span class="p" data-group-id="0050984556-9">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050984556-10">[</span><span class="mi">1</span><span class="p" data-group-id="0050984556-10">]</span><span class="p" data-group-id="0050984556-8">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="0050984556-11">(</span><span class="p" data-group-id="0050984556-12">[</span><span class="mi">3</span><span class="p" data-group-id="0050984556-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050984556-13">[</span><span class="mi">2</span><span class="p">|</span><span class="p" data-group-id="0050984556-14">[</span><span class="mi">1</span><span class="p" data-group-id="0050984556-14">]</span><span class="p">)</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="2857078527-15">(</span><span class="p" data-group-id="2857078527-16">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="2857078527-17">[</span><span class="p" data-group-id="2857078527-17">]</span><span class="p" data-group-id="2857078527-16">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2857078527-18">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2857078527-18">]</span><span class="p" data-group-id="2857078527-15">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="2857078527-19">(</span><span class="p" data-group-id="2857078527-20">[</span><span class="p" data-group-id="2857078527-20">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2857078527-21">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="2857078527-22">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2857078527-22">]</span><span class="p" data-group-id="2857078527-21">]</span><span class="p" data-group-id="2857078527-19">)</span><span class="w">
│ │ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="0050984556-15">(</span><span class="p" data-group-id="0050984556-16">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="0050984556-17">[</span><span class="p" data-group-id="0050984556-17">]</span><span class="p" data-group-id="0050984556-16">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050984556-18">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0050984556-18">]</span><span class="p" data-group-id="0050984556-15">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="0050984556-19">(</span><span class="p" data-group-id="0050984556-20">[</span><span class="p" data-group-id="0050984556-20">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050984556-21">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="0050984556-22">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0050984556-22">]</span><span class="p" data-group-id="0050984556-21">]</span><span class="p" data-group-id="0050984556-19">)</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="2857078527-23">(</span><span class="p" data-group-id="2857078527-24">[</span><span class="p" data-group-id="2857078527-24">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2857078527-25">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2857078527-25">]</span><span class="p" data-group-id="2857078527-23">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2857078527-26">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2857078527-26">]</span></code></pre><p>The module <code class="inline">lists</code> contains many functions for manipulating lists, for example,
│ │ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="0050984556-23">(</span><span class="p" data-group-id="0050984556-24">[</span><span class="p" data-group-id="0050984556-24">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050984556-25">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0050984556-25">]</span><span class="p" data-group-id="0050984556-23">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0050984556-26">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0050984556-26">]</span></code></pre><p>The module <code class="inline">lists</code> contains many functions for manipulating lists, for example,
│ │ │ │  for reversing them. So before writing a list-manipulating function it is a good
│ │ │ │  idea to check if one not already is written for you (see the <a href="../../../lib/stdlib/doc/html/lists.html"><code class="inline">lists</code></a> manual
│ │ │ │  page in STDLIB).</p><p>Now let us get back to the cities and temperatures, but take a more structured
│ │ │ │ -approach this time. First let us convert the whole list to Celsius as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8225648355-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="8225648355-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8225648355-2">(</span><span class="p" data-group-id="8225648355-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8225648355-3">]</span><span class="p" data-group-id="8225648355-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +approach this time. First let us convert the whole list to Celsius as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1529889400-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="1529889400-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1529889400-2">(</span><span class="p" data-group-id="1529889400-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1529889400-3">]</span><span class="p" data-group-id="1529889400-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="8225648355-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8225648355-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8225648355-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8225648355-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="1529889400-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="1529889400-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1529889400-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="1529889400-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8225648355-6">(</span><span class="p" data-group-id="8225648355-7">[</span><span class="p" data-group-id="8225648355-8">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8225648355-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="8225648355-9">}</span><span class="p" data-group-id="8225648355-8">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8225648355-7">]</span><span class="p" data-group-id="8225648355-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8225648355-10">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8225648355-11">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8225648355-12">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="8225648355-12">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="8225648355-11">}</span><span class="p" data-group-id="8225648355-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8225648355-13">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8225648355-14">(</span><span class="n">Rest</span><span class="p" data-group-id="8225648355-14">)</span><span class="p" data-group-id="8225648355-13">]</span><span class="p">;</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8225648355-15">(</span><span class="p" data-group-id="8225648355-16">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8225648355-16">]</span><span class="p" data-group-id="8225648355-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8225648355-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8225648355-18">(</span><span class="n">Rest</span><span class="p" data-group-id="8225648355-18">)</span><span class="p" data-group-id="8225648355-17">]</span><span class="p">;</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8225648355-19">(</span><span class="p" data-group-id="8225648355-20">[</span><span class="p" data-group-id="8225648355-20">]</span><span class="p" data-group-id="8225648355-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8225648355-21">[</span><span class="p" data-group-id="8225648355-21">]</span><span class="p">.</span></code></pre><p>Test the function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">54&gt; </span><span class="nf">c</span><span class="p" data-group-id="4760723435-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="4760723435-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4760723435-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="4760723435-2">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ -55&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="4760723435-3">(</span><span class="p" data-group-id="4760723435-4">[</span><span class="p" data-group-id="4760723435-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="4760723435-6">}</span><span class="p" data-group-id="4760723435-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="4760723435-8">}</span><span class="p" data-group-id="4760723435-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4760723435-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="4760723435-10">}</span><span class="p" data-group-id="4760723435-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="4760723435-12">}</span><span class="p" data-group-id="4760723435-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4760723435-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="4760723435-14">}</span><span class="p" data-group-id="4760723435-13">}</span><span class="p" data-group-id="4760723435-4">]</span><span class="p" data-group-id="4760723435-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4760723435-15">[</span><span class="p" data-group-id="4760723435-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="4760723435-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="4760723435-17">}</span><span class="p" data-group-id="4760723435-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4760723435-18">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="4760723435-19">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">21.11111111111111</span><span class="p" data-group-id="4760723435-19">}</span><span class="p" data-group-id="4760723435-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4760723435-20">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="4760723435-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="4760723435-21">}</span><span class="p" data-group-id="4760723435-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4760723435-22">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="4760723435-23">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="4760723435-23">}</span><span class="p" data-group-id="4760723435-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4760723435-24">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="4760723435-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="4760723435-25">}</span><span class="p" data-group-id="4760723435-24">}</span><span class="p" data-group-id="4760723435-15">]</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">format_temps</span><span class="p" data-group-id="0738547109-1">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="0738547109-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="0738547109-2">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="0738547109-2">)</span><span class="p">.</span></code></pre><p>Here <code class="inline">format_temps/1</code> calls <code class="inline">convert_list_to_c/1</code>. <code class="inline">convert_list_to_c/1</code> takes
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1529889400-6">(</span><span class="p" data-group-id="1529889400-7">[</span><span class="p" data-group-id="1529889400-8">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529889400-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="1529889400-9">}</span><span class="p" data-group-id="1529889400-8">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="1529889400-7">]</span><span class="p" data-group-id="1529889400-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1529889400-10">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529889400-11">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529889400-12">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="1529889400-12">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="1529889400-11">}</span><span class="p" data-group-id="1529889400-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1529889400-13">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1529889400-14">(</span><span class="n">Rest</span><span class="p" data-group-id="1529889400-14">)</span><span class="p" data-group-id="1529889400-13">]</span><span class="p">;</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1529889400-15">(</span><span class="p" data-group-id="1529889400-16">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="1529889400-16">]</span><span class="p" data-group-id="1529889400-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1529889400-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1529889400-18">(</span><span class="n">Rest</span><span class="p" data-group-id="1529889400-18">)</span><span class="p" data-group-id="1529889400-17">]</span><span class="p">;</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1529889400-19">(</span><span class="p" data-group-id="1529889400-20">[</span><span class="p" data-group-id="1529889400-20">]</span><span class="p" data-group-id="1529889400-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1529889400-21">[</span><span class="p" data-group-id="1529889400-21">]</span><span class="p">.</span></code></pre><p>Test the function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">54&gt; </span><span class="nf">c</span><span class="p" data-group-id="2623671147-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="2623671147-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2623671147-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="2623671147-2">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ +55&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="2623671147-3">(</span><span class="p" data-group-id="2623671147-4">[</span><span class="p" data-group-id="2623671147-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="2623671147-6">}</span><span class="p" data-group-id="2623671147-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="2623671147-8">}</span><span class="p" data-group-id="2623671147-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2623671147-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="2623671147-10">}</span><span class="p" data-group-id="2623671147-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="2623671147-12">}</span><span class="p" data-group-id="2623671147-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2623671147-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="2623671147-14">}</span><span class="p" data-group-id="2623671147-13">}</span><span class="p" data-group-id="2623671147-4">]</span><span class="p" data-group-id="2623671147-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2623671147-15">[</span><span class="p" data-group-id="2623671147-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="2623671147-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="2623671147-17">}</span><span class="p" data-group-id="2623671147-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2623671147-18">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="2623671147-19">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">21.11111111111111</span><span class="p" data-group-id="2623671147-19">}</span><span class="p" data-group-id="2623671147-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2623671147-20">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="2623671147-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="2623671147-21">}</span><span class="p" data-group-id="2623671147-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2623671147-22">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="2623671147-23">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="2623671147-23">}</span><span class="p" data-group-id="2623671147-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2623671147-24">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="2623671147-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="2623671147-25">}</span><span class="p" data-group-id="2623671147-24">}</span><span class="p" data-group-id="2623671147-15">]</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">format_temps</span><span class="p" data-group-id="6156229066-1">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="6156229066-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="6156229066-2">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="6156229066-2">)</span><span class="p">.</span></code></pre><p>Here <code class="inline">format_temps/1</code> calls <code class="inline">convert_list_to_c/1</code>. <code class="inline">convert_list_to_c/1</code> takes
│ │ │ │  off the head of the <code class="inline">List_of_cities</code>, converts it to Celsius if needed. The <code class="inline">|</code>
│ │ │ │ -operator is used to add the (maybe) converted to the converted rest of the list:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0919274555-1">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="0919274555-2">(</span><span class="n">Rest</span><span class="p" data-group-id="0919274555-2">)</span><span class="p" data-group-id="0919274555-1">]</span><span class="p">;</span></code></pre><p>or:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1821739226-1">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1821739226-2">(</span><span class="n">Rest</span><span class="p" data-group-id="1821739226-2">)</span><span class="p" data-group-id="1821739226-1">]</span><span class="p">;</span></code></pre><p>This is done until the end of the list is reached, that is, the list is empty:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_list_to_c</span><span class="p" data-group-id="5118421681-1">(</span><span class="p" data-group-id="5118421681-2">[</span><span class="p" data-group-id="5118421681-2">]</span><span class="p" data-group-id="5118421681-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5118421681-3">[</span><span class="p" data-group-id="5118421681-3">]</span><span class="p">.</span></code></pre><p>Now when the list is converted, a function to print it is added:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4453444027-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="4453444027-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4453444027-2">(</span><span class="p" data-group-id="4453444027-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4453444027-3">]</span><span class="p" data-group-id="4453444027-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="4453444027-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="4453444027-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4453444027-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="4453444027-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="4453444027-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="4453444027-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4453444027-7">(</span><span class="p" data-group-id="4453444027-8">[</span><span class="p" data-group-id="4453444027-9">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4453444027-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="4453444027-10">}</span><span class="p" data-group-id="4453444027-9">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4453444027-8">]</span><span class="p" data-group-id="4453444027-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4453444027-11">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4453444027-12">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4453444027-13">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="4453444027-13">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="4453444027-12">}</span><span class="p" data-group-id="4453444027-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4453444027-14">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4453444027-15">(</span><span class="n">Rest</span><span class="p" data-group-id="4453444027-15">)</span><span class="p" data-group-id="4453444027-14">]</span><span class="p">;</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4453444027-16">(</span><span class="p" data-group-id="4453444027-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4453444027-17">]</span><span class="p" data-group-id="4453444027-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4453444027-18">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4453444027-19">(</span><span class="n">Rest</span><span class="p" data-group-id="4453444027-19">)</span><span class="p" data-group-id="4453444027-18">]</span><span class="p">;</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4453444027-20">(</span><span class="p" data-group-id="4453444027-21">[</span><span class="p" data-group-id="4453444027-21">]</span><span class="p" data-group-id="4453444027-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4453444027-22">[</span><span class="p" data-group-id="4453444027-22">]</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="4453444027-23">(</span><span class="p" data-group-id="4453444027-24">[</span><span class="p" data-group-id="4453444027-25">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4453444027-26">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="4453444027-26">}</span><span class="p" data-group-id="4453444027-25">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4453444027-24">]</span><span class="p" data-group-id="4453444027-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4453444027-27">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4453444027-28">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="4453444027-28">]</span><span class="p" data-group-id="4453444027-27">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="4453444027-29">(</span><span class="n">Rest</span><span class="p" data-group-id="4453444027-29">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="4453444027-30">(</span><span class="p" data-group-id="4453444027-31">[</span><span class="p" data-group-id="4453444027-31">]</span><span class="p" data-group-id="4453444027-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ok</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">56&gt; </span><span class="nf">c</span><span class="p" data-group-id="8255218947-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="8255218947-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8255218947-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut7</span><span class="p" data-group-id="8255218947-2">}</span><span class="gp unselectable">
│ │ │ │ -57&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="8255218947-3">(</span><span class="p" data-group-id="8255218947-4">[</span><span class="p" data-group-id="8255218947-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="8255218947-6">}</span><span class="p" data-group-id="8255218947-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="8255218947-8">}</span><span class="p" data-group-id="8255218947-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8255218947-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="8255218947-10">}</span><span class="p" data-group-id="8255218947-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="8255218947-12">}</span><span class="p" data-group-id="8255218947-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8255218947-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="8255218947-14">}</span><span class="p" data-group-id="8255218947-13">}</span><span class="p" data-group-id="8255218947-4">]</span><span class="p" data-group-id="8255218947-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +operator is used to add the (maybe) converted to the converted rest of the list:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1384200589-1">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1384200589-2">(</span><span class="n">Rest</span><span class="p" data-group-id="1384200589-2">)</span><span class="p" data-group-id="1384200589-1">]</span><span class="p">;</span></code></pre><p>or:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4643217224-1">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4643217224-2">(</span><span class="n">Rest</span><span class="p" data-group-id="4643217224-2">)</span><span class="p" data-group-id="4643217224-1">]</span><span class="p">;</span></code></pre><p>This is done until the end of the list is reached, that is, the list is empty:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2426323026-1">(</span><span class="p" data-group-id="2426323026-2">[</span><span class="p" data-group-id="2426323026-2">]</span><span class="p" data-group-id="2426323026-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2426323026-3">[</span><span class="p" data-group-id="2426323026-3">]</span><span class="p">.</span></code></pre><p>Now when the list is converted, a function to print it is added:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2291681056-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="2291681056-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2291681056-2">(</span><span class="p" data-group-id="2291681056-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2291681056-3">]</span><span class="p" data-group-id="2291681056-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="2291681056-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="2291681056-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2291681056-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="2291681056-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="2291681056-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="2291681056-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2291681056-7">(</span><span class="p" data-group-id="2291681056-8">[</span><span class="p" data-group-id="2291681056-9">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2291681056-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="2291681056-10">}</span><span class="p" data-group-id="2291681056-9">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="2291681056-8">]</span><span class="p" data-group-id="2291681056-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2291681056-11">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2291681056-12">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2291681056-13">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="2291681056-13">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="2291681056-12">}</span><span class="p" data-group-id="2291681056-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2291681056-14">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2291681056-15">(</span><span class="n">Rest</span><span class="p" data-group-id="2291681056-15">)</span><span class="p" data-group-id="2291681056-14">]</span><span class="p">;</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2291681056-16">(</span><span class="p" data-group-id="2291681056-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="2291681056-17">]</span><span class="p" data-group-id="2291681056-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2291681056-18">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2291681056-19">(</span><span class="n">Rest</span><span class="p" data-group-id="2291681056-19">)</span><span class="p" data-group-id="2291681056-18">]</span><span class="p">;</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2291681056-20">(</span><span class="p" data-group-id="2291681056-21">[</span><span class="p" data-group-id="2291681056-21">]</span><span class="p" data-group-id="2291681056-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2291681056-22">[</span><span class="p" data-group-id="2291681056-22">]</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="2291681056-23">(</span><span class="p" data-group-id="2291681056-24">[</span><span class="p" data-group-id="2291681056-25">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2291681056-26">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2291681056-26">}</span><span class="p" data-group-id="2291681056-25">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="2291681056-24">]</span><span class="p" data-group-id="2291681056-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2291681056-27">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2291681056-28">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2291681056-28">]</span><span class="p" data-group-id="2291681056-27">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="2291681056-29">(</span><span class="n">Rest</span><span class="p" data-group-id="2291681056-29">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="2291681056-30">(</span><span class="p" data-group-id="2291681056-31">[</span><span class="p" data-group-id="2291681056-31">]</span><span class="p" data-group-id="2291681056-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ok</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">56&gt; </span><span class="nf">c</span><span class="p" data-group-id="2401756192-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="2401756192-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2401756192-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut7</span><span class="p" data-group-id="2401756192-2">}</span><span class="gp unselectable">
│ │ │ │ +57&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="2401756192-3">(</span><span class="p" data-group-id="2401756192-4">[</span><span class="p" data-group-id="2401756192-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="2401756192-6">}</span><span class="p" data-group-id="2401756192-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="2401756192-8">}</span><span class="p" data-group-id="2401756192-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2401756192-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="2401756192-10">}</span><span class="p" data-group-id="2401756192-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="2401756192-12">}</span><span class="p" data-group-id="2401756192-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2401756192-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="2401756192-14">}</span><span class="p" data-group-id="2401756192-13">}</span><span class="p" data-group-id="2401756192-4">]</span><span class="p" data-group-id="2401756192-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="o">-</span><span class="mi">4</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>Now a function has to be added to find the cities with the maximum and minimum
│ │ │ │  temperatures. The following program is not the most efficient way of doing this
│ │ │ │  as you walk through the list of cities four times. But it is better to first
│ │ │ │  strive for clarity and correctness and to make programs efficient only if
│ │ │ │ -needed.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9067568474-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="9067568474-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9067568474-2">(</span><span class="p" data-group-id="9067568474-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9067568474-3">]</span><span class="p" data-group-id="9067568474-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +needed.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8743405591-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="8743405591-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8743405591-2">(</span><span class="p" data-group-id="8743405591-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8743405591-3">]</span><span class="p" data-group-id="8743405591-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="9067568474-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="9067568474-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9067568474-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="9067568474-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="9067568474-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="9067568474-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9067568474-7">{</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="9067568474-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9067568474-8">(</span><span class="n">Converted_List</span><span class="p" data-group-id="9067568474-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">print_max_and_min</span><span class="p" data-group-id="9067568474-9">(</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="9067568474-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9067568474-10">(</span><span class="p" data-group-id="9067568474-11">[</span><span class="p" data-group-id="9067568474-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-13">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9067568474-13">}</span><span class="p" data-group-id="9067568474-12">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9067568474-11">]</span><span class="p" data-group-id="9067568474-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9067568474-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-16">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="9067568474-16">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="9067568474-15">}</span><span class="p" data-group-id="9067568474-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9067568474-17">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9067568474-18">(</span><span class="n">Rest</span><span class="p" data-group-id="9067568474-18">)</span><span class="p" data-group-id="9067568474-17">]</span><span class="p">;</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9067568474-19">(</span><span class="p" data-group-id="9067568474-20">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9067568474-20">]</span><span class="p" data-group-id="9067568474-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9067568474-21">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9067568474-22">(</span><span class="n">Rest</span><span class="p" data-group-id="9067568474-22">)</span><span class="p" data-group-id="9067568474-21">]</span><span class="p">;</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9067568474-23">(</span><span class="p" data-group-id="9067568474-24">[</span><span class="p" data-group-id="9067568474-24">]</span><span class="p" data-group-id="9067568474-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9067568474-25">[</span><span class="p" data-group-id="9067568474-25">]</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="9067568474-26">(</span><span class="p" data-group-id="9067568474-27">[</span><span class="p" data-group-id="9067568474-28">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-29">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9067568474-29">}</span><span class="p" data-group-id="9067568474-28">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9067568474-27">]</span><span class="p" data-group-id="9067568474-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9067568474-30">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-31">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9067568474-31">]</span><span class="p" data-group-id="9067568474-30">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="9067568474-32">(</span><span class="n">Rest</span><span class="p" data-group-id="9067568474-32">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="9067568474-33">(</span><span class="p" data-group-id="9067568474-34">[</span><span class="p" data-group-id="9067568474-34">]</span><span class="p" data-group-id="9067568474-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="8743405591-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8743405591-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8743405591-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8743405591-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="8743405591-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="8743405591-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8743405591-7">{</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="8743405591-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8743405591-8">(</span><span class="n">Converted_List</span><span class="p" data-group-id="8743405591-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">print_max_and_min</span><span class="p" data-group-id="8743405591-9">(</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="8743405591-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8743405591-10">(</span><span class="p" data-group-id="8743405591-11">[</span><span class="p" data-group-id="8743405591-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-13">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8743405591-13">}</span><span class="p" data-group-id="8743405591-12">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8743405591-11">]</span><span class="p" data-group-id="8743405591-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8743405591-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-16">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="8743405591-16">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="8743405591-15">}</span><span class="p" data-group-id="8743405591-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8743405591-17">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8743405591-18">(</span><span class="n">Rest</span><span class="p" data-group-id="8743405591-18">)</span><span class="p" data-group-id="8743405591-17">]</span><span class="p">;</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8743405591-19">(</span><span class="p" data-group-id="8743405591-20">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8743405591-20">]</span><span class="p" data-group-id="8743405591-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8743405591-21">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8743405591-22">(</span><span class="n">Rest</span><span class="p" data-group-id="8743405591-22">)</span><span class="p" data-group-id="8743405591-21">]</span><span class="p">;</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8743405591-23">(</span><span class="p" data-group-id="8743405591-24">[</span><span class="p" data-group-id="8743405591-24">]</span><span class="p" data-group-id="8743405591-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8743405591-25">[</span><span class="p" data-group-id="8743405591-25">]</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="8743405591-26">(</span><span class="p" data-group-id="8743405591-27">[</span><span class="p" data-group-id="8743405591-28">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-29">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8743405591-29">}</span><span class="p" data-group-id="8743405591-28">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8743405591-27">]</span><span class="p" data-group-id="8743405591-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8743405591-30">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-31">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8743405591-31">]</span><span class="p" data-group-id="8743405591-30">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="8743405591-32">(</span><span class="n">Rest</span><span class="p" data-group-id="8743405591-32">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="8743405591-33">(</span><span class="p" data-group-id="8743405591-34">[</span><span class="p" data-group-id="8743405591-34">]</span><span class="p" data-group-id="8743405591-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9067568474-35">(</span><span class="p" data-group-id="9067568474-36">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9067568474-36">]</span><span class="p" data-group-id="9067568474-35">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9067568474-37">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p" data-group-id="9067568474-37">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8743405591-35">(</span><span class="p" data-group-id="8743405591-36">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8743405591-36">]</span><span class="p" data-group-id="8743405591-35">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8743405591-37">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p" data-group-id="8743405591-37">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9067568474-38">(</span><span class="p" data-group-id="9067568474-39">[</span><span class="p" data-group-id="9067568474-40">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-41">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9067568474-41">}</span><span class="p" data-group-id="9067568474-40">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9067568474-39">]</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="9067568474-42">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-43">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="9067568474-43">}</span><span class="p" data-group-id="9067568474-42">}</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="9067568474-44">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-45">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="9067568474-45">}</span><span class="p" data-group-id="9067568474-44">}</span><span class="p" data-group-id="9067568474-38">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8743405591-38">(</span><span class="p" data-group-id="8743405591-39">[</span><span class="p" data-group-id="8743405591-40">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-41">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8743405591-41">}</span><span class="p" data-group-id="8743405591-40">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8743405591-39">]</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="8743405591-42">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-43">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="8743405591-43">}</span><span class="p" data-group-id="8743405591-42">}</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="8743405591-44">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-45">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="8743405591-45">}</span><span class="p" data-group-id="8743405591-44">}</span><span class="p" data-group-id="8743405591-38">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">Temp</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Max_Temp</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9067568474-46">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-47">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9067568474-47">}</span><span class="p" data-group-id="9067568474-46">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │ │ +            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8743405591-46">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-47">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8743405591-47">}</span><span class="p" data-group-id="8743405591-46">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9067568474-48">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-49">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="9067568474-49">}</span><span class="p" data-group-id="9067568474-48">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │ │ +            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8743405591-48">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-49">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="8743405591-49">}</span><span class="p" data-group-id="8743405591-48">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │           </span><span class="n">Temp</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Min_Temp</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9067568474-50">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-51">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9067568474-51">}</span><span class="p" data-group-id="9067568474-50">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │ │ +            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8743405591-50">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-51">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8743405591-51">}</span><span class="p" data-group-id="8743405591-50">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9067568474-52">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-53">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="9067568474-53">}</span><span class="p" data-group-id="9067568474-52">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │ │ +            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8743405591-52">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-53">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="8743405591-53">}</span><span class="p" data-group-id="8743405591-52">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9067568474-54">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="9067568474-54">)</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8743405591-54">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="8743405591-54">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9067568474-55">(</span><span class="p" data-group-id="9067568474-56">[</span><span class="p" data-group-id="9067568474-56">]</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="9067568474-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9067568474-57">{</span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="9067568474-57">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8743405591-55">(</span><span class="p" data-group-id="8743405591-56">[</span><span class="p" data-group-id="8743405591-56">]</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="8743405591-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8743405591-57">{</span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="8743405591-57">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">print_max_and_min</span><span class="p" data-group-id="9067568474-58">(</span><span class="p" data-group-id="9067568474-59">{</span><span class="n">Max_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-60">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_temp</span><span class="p" data-group-id="9067568474-60">}</span><span class="p" data-group-id="9067568474-59">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-61">{</span><span class="n">Min_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-62">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_temp</span><span class="p" data-group-id="9067568474-62">}</span><span class="p" data-group-id="9067568474-61">}</span><span class="p" data-group-id="9067568474-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9067568474-63">(</span><span class="s">&quot;Max temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-64">[</span><span class="n">Max_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Max_name</span><span class="p" data-group-id="9067568474-64">]</span><span class="p" data-group-id="9067568474-63">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9067568474-65">(</span><span class="s">&quot;Min temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9067568474-66">[</span><span class="n">Min_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Min_name</span><span class="p" data-group-id="9067568474-66">]</span><span class="p" data-group-id="9067568474-65">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">58&gt; </span><span class="nf">c</span><span class="p" data-group-id="7712101596-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="7712101596-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7712101596-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="7712101596-2">}</span><span class="gp unselectable">
│ │ │ │ -59&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="7712101596-3">(</span><span class="p" data-group-id="7712101596-4">[</span><span class="p" data-group-id="7712101596-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="7712101596-6">}</span><span class="p" data-group-id="7712101596-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="7712101596-8">}</span><span class="p" data-group-id="7712101596-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7712101596-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="7712101596-10">}</span><span class="p" data-group-id="7712101596-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="7712101596-12">}</span><span class="p" data-group-id="7712101596-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7712101596-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="7712101596-14">}</span><span class="p" data-group-id="7712101596-13">}</span><span class="p" data-group-id="7712101596-4">]</span><span class="p" data-group-id="7712101596-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">print_max_and_min</span><span class="p" data-group-id="8743405591-58">(</span><span class="p" data-group-id="8743405591-59">{</span><span class="n">Max_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-60">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_temp</span><span class="p" data-group-id="8743405591-60">}</span><span class="p" data-group-id="8743405591-59">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-61">{</span><span class="n">Min_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-62">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_temp</span><span class="p" data-group-id="8743405591-62">}</span><span class="p" data-group-id="8743405591-61">}</span><span class="p" data-group-id="8743405591-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8743405591-63">(</span><span class="s">&quot;Max temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-64">[</span><span class="n">Max_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Max_name</span><span class="p" data-group-id="8743405591-64">]</span><span class="p" data-group-id="8743405591-63">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8743405591-65">(</span><span class="s">&quot;Min temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8743405591-66">[</span><span class="n">Min_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Min_name</span><span class="p" data-group-id="8743405591-66">]</span><span class="p" data-group-id="8743405591-65">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">58&gt; </span><span class="nf">c</span><span class="p" data-group-id="8445888635-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="8445888635-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8445888635-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="8445888635-2">}</span><span class="gp unselectable">
│ │ │ │ +59&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="8445888635-3">(</span><span class="p" data-group-id="8445888635-4">[</span><span class="p" data-group-id="8445888635-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="8445888635-6">}</span><span class="p" data-group-id="8445888635-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="8445888635-8">}</span><span class="p" data-group-id="8445888635-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8445888635-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="8445888635-10">}</span><span class="p" data-group-id="8445888635-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="8445888635-12">}</span><span class="p" data-group-id="8445888635-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8445888635-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="8445888635-14">}</span><span class="p" data-group-id="8445888635-13">}</span><span class="p" data-group-id="8445888635-4">]</span><span class="p" data-group-id="8445888635-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="o">-</span><span class="mi">4</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │ │  </span><span class="n">Max</span><span class="w"> </span><span class="ss">temperature</span><span class="w"> </span><span class="ss">was</span><span class="w"> </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">cape_town</span><span class="w">
│ │ │ │  </span><span class="n">Min</span><span class="w"> </span><span class="ss">temperature</span><span class="w"> </span><span class="ss">was</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">moscow</span><span class="w">
│ │ │ │ @@ -678,88 +678,88 @@
│ │ │ │          Action 4
│ │ │ │  end</code></pre><p>Notice that there is no <code class="inline">;</code> before <code class="inline">end</code>. Conditions do the same as guards, that
│ │ │ │  is, tests that succeed or fail. Erlang starts at the top and tests until it
│ │ │ │  finds a condition that succeeds. Then it evaluates (performs) the action
│ │ │ │  following the condition and ignores all other conditions and actions before the
│ │ │ │  <code class="inline">end</code>. If no condition matches, a run-time failure occurs. A condition that
│ │ │ │  always succeeds is the atom <code class="inline">true</code>. This is often used last in an <code class="inline">if</code>, meaning,
│ │ │ │ -do the action following the <code class="inline">true</code> if all other conditions have failed.</p><p>The following is a short program to show the workings of <code class="inline">if</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8794944305-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="8794944305-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8794944305-2">(</span><span class="p" data-group-id="8794944305-3">[</span><span class="ss">test_if</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8794944305-3">]</span><span class="p" data-group-id="8794944305-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +do the action following the <code class="inline">true</code> if all other conditions have failed.</p><p>The following is a short program to show the workings of <code class="inline">if</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0701991500-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="0701991500-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0701991500-2">(</span><span class="p" data-group-id="0701991500-3">[</span><span class="ss">test_if</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0701991500-3">]</span><span class="p" data-group-id="0701991500-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">test_if</span><span class="p" data-group-id="8794944305-4">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="8794944305-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">test_if</span><span class="p" data-group-id="0701991500-4">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="0701991500-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8794944305-5">(</span><span class="s">&quot;A == 5</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8794944305-6">[</span><span class="p" data-group-id="8794944305-6">]</span><span class="p" data-group-id="8794944305-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0701991500-5">(</span><span class="s">&quot;A == 5</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0701991500-6">[</span><span class="p" data-group-id="0701991500-6">]</span><span class="p" data-group-id="0701991500-5">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="ss">a_equals_5</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">6</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8794944305-7">(</span><span class="s">&quot;B == 6</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8794944305-8">[</span><span class="p" data-group-id="8794944305-8">]</span><span class="p" data-group-id="8794944305-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0701991500-7">(</span><span class="s">&quot;B == 6</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0701991500-8">[</span><span class="p" data-group-id="0701991500-8">]</span><span class="p" data-group-id="0701991500-7">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="ss">b_equals_6</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">                      </span><span class="c1">%That is A equals 2 and B equals 3</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8794944305-9">(</span><span class="s">&quot;A == 2, B == 3</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8794944305-10">[</span><span class="p" data-group-id="8794944305-10">]</span><span class="p" data-group-id="8794944305-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0701991500-9">(</span><span class="s">&quot;A == 2, B == 3</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0701991500-10">[</span><span class="p" data-group-id="0701991500-10">]</span><span class="p" data-group-id="0701991500-9">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="ss">a_equals_2_b_equals_3</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">7</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">                     </span><span class="c1">%That is A equals 1 or B equals 7</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8794944305-11">(</span><span class="s">&quot;A == 1 ; B == 7</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8794944305-12">[</span><span class="p" data-group-id="8794944305-12">]</span><span class="p" data-group-id="8794944305-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0701991500-11">(</span><span class="s">&quot;A == 1 ; B == 7</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0701991500-12">[</span><span class="p" data-group-id="0701991500-12">]</span><span class="p" data-group-id="0701991500-11">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="ss">a_equals_1_or_b_equals_7</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Testing this program gives:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">60&gt; </span><span class="nf">c</span><span class="p" data-group-id="8700987245-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="8700987245-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8700987245-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut9</span><span class="p" data-group-id="8700987245-2">}</span><span class="gp unselectable">
│ │ │ │ -61&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="8700987245-3">(</span><span class="mi">5</span><span class="p">,</span><span class="mi">33</span><span class="p" data-group-id="8700987245-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Testing this program gives:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">60&gt; </span><span class="nf">c</span><span class="p" data-group-id="1829004104-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="1829004104-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1829004104-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut9</span><span class="p" data-group-id="1829004104-2">}</span><span class="gp unselectable">
│ │ │ │ +61&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1829004104-3">(</span><span class="mi">5</span><span class="p">,</span><span class="mi">33</span><span class="p" data-group-id="1829004104-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │ │  </span><span class="ss">a_equals_5</span><span class="gp unselectable">
│ │ │ │ -62&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="8700987245-4">(</span><span class="mi">33</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8700987245-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +62&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1829004104-4">(</span><span class="mi">33</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="1829004104-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">6</span><span class="w">
│ │ │ │  </span><span class="ss">b_equals_6</span><span class="gp unselectable">
│ │ │ │ -63&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="8700987245-5">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="8700987245-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +63&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1829004104-5">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1829004104-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">3</span><span class="w">
│ │ │ │  </span><span class="ss">a_equals_2_b_equals_3</span><span class="gp unselectable">
│ │ │ │ -64&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="8700987245-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="8700987245-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +64&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1829004104-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="1829004104-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">7</span><span class="w">
│ │ │ │  </span><span class="ss">a_equals_1_or_b_equals_7</span><span class="gp unselectable">
│ │ │ │ -65&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="8700987245-7">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p" data-group-id="8700987245-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +65&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1829004104-7">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p" data-group-id="1829004104-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">7</span><span class="w">
│ │ │ │  </span><span class="ss">a_equals_1_or_b_equals_7</span><span class="gp unselectable">
│ │ │ │ -66&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="8700987245-8">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="8700987245-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +66&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1829004104-8">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="1829004104-8">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no true branch found when evaluating an if expression
│ │ │ │       in function  tut9:test_if/2 (tut9.erl, line 5)</span></code></pre><p>Notice that <code class="inline">tut9:test_if(33,33)</code> does not cause any condition to succeed. This
│ │ │ │  leads to the run time error <code class="inline">if_clause</code>, here nicely formatted by the shell. See
│ │ │ │  <a href="../../../lib/../system/doc/html/expressions.xhtml">Guard Sequences</a> for details of the many guard tests
│ │ │ │  available.</p><p><code class="inline">case</code> is another construct in Erlang. Recall that the <code class="inline">convert_length</code> function
│ │ │ │ -was written as:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_length</span><span class="p" data-group-id="8470078916-1">(</span><span class="p" data-group-id="8470078916-2">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8470078916-2">}</span><span class="p" data-group-id="8470078916-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8470078916-3">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="8470078916-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="8470078916-4">(</span><span class="p" data-group-id="8470078916-5">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8470078916-5">}</span><span class="p" data-group-id="8470078916-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8470078916-6">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="8470078916-6">}</span><span class="p">.</span></code></pre><p>The same program can also be written as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9660130201-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="9660130201-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9660130201-2">(</span><span class="p" data-group-id="9660130201-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9660130201-3">]</span><span class="p" data-group-id="9660130201-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +was written as:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_length</span><span class="p" data-group-id="9262378520-1">(</span><span class="p" data-group-id="9262378520-2">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="9262378520-2">}</span><span class="p" data-group-id="9262378520-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9262378520-3">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9262378520-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="9262378520-4">(</span><span class="p" data-group-id="9262378520-5">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9262378520-5">}</span><span class="p" data-group-id="9262378520-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9262378520-6">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9262378520-6">}</span><span class="p">.</span></code></pre><p>The same program can also be written as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7453642703-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="7453642703-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7453642703-2">(</span><span class="p" data-group-id="7453642703-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7453642703-3">]</span><span class="p" data-group-id="7453642703-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="9660130201-4">(</span><span class="n">Length</span><span class="p" data-group-id="9660130201-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="7453642703-4">(</span><span class="n">Length</span><span class="p" data-group-id="7453642703-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="9660130201-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="9660130201-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="9660130201-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9660130201-6">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="9660130201-7">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9660130201-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="9660130201-8">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9660130201-8">}</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">67&gt; </span><span class="nf">c</span><span class="p" data-group-id="2530989216-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="2530989216-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2530989216-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut10</span><span class="p" data-group-id="2530989216-2">}</span><span class="gp unselectable">
│ │ │ │ -68&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="2530989216-3">(</span><span class="p" data-group-id="2530989216-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="2530989216-4">}</span><span class="p" data-group-id="2530989216-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2530989216-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">15.24</span><span class="p" data-group-id="2530989216-5">}</span><span class="gp unselectable">
│ │ │ │ -69&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="2530989216-6">(</span><span class="p" data-group-id="2530989216-7">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="mf">2.5</span><span class="p" data-group-id="2530989216-7">}</span><span class="p" data-group-id="2530989216-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2530989216-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">0.984251968503937</span><span class="p" data-group-id="2530989216-8">}</span></code></pre><p>Both <code class="inline">case</code> and <code class="inline">if</code> have <em>return values</em>, that is, in the above example <code class="inline">case</code>
│ │ │ │ +        </span><span class="p" data-group-id="7453642703-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7453642703-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="7453642703-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="7453642703-6">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7453642703-7">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7453642703-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="7453642703-8">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="7453642703-8">}</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">67&gt; </span><span class="nf">c</span><span class="p" data-group-id="9558355181-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="9558355181-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9558355181-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut10</span><span class="p" data-group-id="9558355181-2">}</span><span class="gp unselectable">
│ │ │ │ +68&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="9558355181-3">(</span><span class="p" data-group-id="9558355181-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="9558355181-4">}</span><span class="p" data-group-id="9558355181-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9558355181-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">15.24</span><span class="p" data-group-id="9558355181-5">}</span><span class="gp unselectable">
│ │ │ │ +69&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="9558355181-6">(</span><span class="p" data-group-id="9558355181-7">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="mf">2.5</span><span class="p" data-group-id="9558355181-7">}</span><span class="p" data-group-id="9558355181-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9558355181-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">0.984251968503937</span><span class="p" data-group-id="9558355181-8">}</span></code></pre><p>Both <code class="inline">case</code> and <code class="inline">if</code> have <em>return values</em>, that is, in the above example <code class="inline">case</code>
│ │ │ │  returned either <code class="inline">{inch,X/2.54}</code> or <code class="inline">{centimeter,Y*2.54}</code>. The behaviour of
│ │ │ │  <code class="inline">case</code> can also be modified by using guards. The following example clarifies
│ │ │ │  this. It tells us the length of a month, given the year. The year must be known,
│ │ │ │ -since February has 29 days in a leap year.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6556049943-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="6556049943-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6556049943-2">(</span><span class="p" data-group-id="6556049943-3">[</span><span class="ss">month_length</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6556049943-3">]</span><span class="p" data-group-id="6556049943-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +since February has 29 days in a leap year.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9230170820-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="9230170820-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9230170820-2">(</span><span class="p" data-group-id="9230170820-3">[</span><span class="ss">month_length</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9230170820-3">]</span><span class="p" data-group-id="9230170820-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">month_length</span><span class="p" data-group-id="6556049943-4">(</span><span class="n">Year</span><span class="p">,</span><span class="w"> </span><span class="n">Month</span><span class="p" data-group-id="6556049943-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">month_length</span><span class="p" data-group-id="9230170820-4">(</span><span class="n">Year</span><span class="p">,</span><span class="w"> </span><span class="n">Month</span><span class="p" data-group-id="9230170820-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% All years divisible by 400 are leap</span><span class="w">
│ │ │ │      </span><span class="c1">%% Years divisible by 100 are not leap (except the 400 rule above)</span><span class="w">
│ │ │ │      </span><span class="c1">%% Years divisible by 4 are leap (except the 100 rule above)</span><span class="w">
│ │ │ │      </span><span class="n">Leap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">if</span><span class="w">
│ │ │ │ -        </span><span class="nf">trunc</span><span class="p" data-group-id="6556049943-5">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="6556049943-5">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nf">trunc</span><span class="p" data-group-id="9230170820-5">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="9230170820-5">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">leap</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="nf">trunc</span><span class="p" data-group-id="6556049943-6">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="6556049943-6">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">100</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nf">trunc</span><span class="p" data-group-id="9230170820-6">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="9230170820-6">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">100</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">not_leap</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="nf">trunc</span><span class="p" data-group-id="6556049943-7">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="6556049943-7">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">4</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nf">trunc</span><span class="p" data-group-id="9230170820-7">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="9230170820-7">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">4</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">leap</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">not_leap</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Month</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">sep</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">30</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">apr</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">30</span><span class="p">;</span><span class="w">
│ │ │ │ @@ -770,151 +770,151 @@
│ │ │ │          </span><span class="ss">jan</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">mar</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">may</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">jul</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">aug</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">oct</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">dec</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">70&gt; </span><span class="nf">c</span><span class="p" data-group-id="8927256463-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="8927256463-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8927256463-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut11</span><span class="p" data-group-id="8927256463-2">}</span><span class="gp unselectable">
│ │ │ │ -71&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="8927256463-3">(</span><span class="mi">2004</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="8927256463-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">70&gt; </span><span class="nf">c</span><span class="p" data-group-id="4773876657-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="4773876657-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4773876657-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut11</span><span class="p" data-group-id="4773876657-2">}</span><span class="gp unselectable">
│ │ │ │ +71&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="4773876657-3">(</span><span class="mi">2004</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="4773876657-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">29</span><span class="gp unselectable">
│ │ │ │ -72&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="8927256463-4">(</span><span class="mi">2003</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="8927256463-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +72&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="4773876657-4">(</span><span class="mi">2003</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="4773876657-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">28</span><span class="gp unselectable">
│ │ │ │ -73&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="8927256463-5">(</span><span class="mi">1947</span><span class="p">,</span><span class="w"> </span><span class="ss">aug</span><span class="p" data-group-id="8927256463-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +73&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="4773876657-5">(</span><span class="mi">1947</span><span class="p">,</span><span class="w"> </span><span class="ss">aug</span><span class="p" data-group-id="4773876657-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">31</span></code></pre><h2 id="built-in-functions-bifs" class="section-heading">
│ │ │ │    <a href="#built-in-functions-bifs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Built-In Functions (BIFs)</span>
│ │ │ │  </h2>
│ │ │ │  <p>BIFs are functions that for some reason are built-in to the Erlang virtual
│ │ │ │  machine. BIFs often implement functionality that is impossible or is too
│ │ │ │  inefficient to implement in Erlang. Some BIFs can be called using the function
│ │ │ │  name only but they are by default belonging to the <code class="inline">erlang</code> module. For example,
│ │ │ │  the call to the BIF <code class="inline">trunc</code> below is equivalent to a call to <code class="inline">erlang:trunc</code>.</p><p>As shown, first it is checked if a year is leap. If a year is divisible by 400,
│ │ │ │  it is a leap year. To determine this, first divide the year by 400 and use the
│ │ │ │  BIF <code class="inline">trunc</code> (more about this later) to cut off any decimals. Then multiply by
│ │ │ │  400 again and see if the same value is returned again. For example, year 2004:</p><pre><code class="makeup erlang" translate="no"><span class="mi">2004</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mf">5.01</span><span class="w">
│ │ │ │ -</span><span class="nf">trunc</span><span class="p" data-group-id="0566180782-1">(</span><span class="mf">5.01</span><span class="p" data-group-id="0566180782-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │ │ +</span><span class="nf">trunc</span><span class="p" data-group-id="4438328787-1">(</span><span class="mf">5.01</span><span class="p" data-group-id="4438328787-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │ │  </span><span class="mi">5</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2000</span></code></pre><p>2000 is not the same as 2004, so 2004 is not divisible by 400. Year 2000:</p><pre><code class="makeup erlang" translate="no"><span class="mi">2000</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mf">5.0</span><span class="w">
│ │ │ │ -</span><span class="nf">trunc</span><span class="p" data-group-id="2740057232-1">(</span><span class="mf">5.0</span><span class="p" data-group-id="2740057232-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │ │ +</span><span class="nf">trunc</span><span class="p" data-group-id="3449188208-1">(</span><span class="mf">5.0</span><span class="p" data-group-id="3449188208-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │ │  </span><span class="mi">5</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2000</span></code></pre><p>That is, a leap year. The next two <code class="inline">trunc</code>-tests evaluate if the year is
│ │ │ │  divisible by 100 or 4 in the same way. The first <code class="inline">if</code> returns <code class="inline">leap</code> or
│ │ │ │  <code class="inline">not_leap</code>, which lands up in the variable <code class="inline">Leap</code>. This variable is used in the
│ │ │ │  guard for <code class="inline">feb</code> in the following <code class="inline">case</code> that tells us how long the month is.</p><p>This example showed the use of <code class="inline">trunc</code>. It is easier to use the Erlang operator
│ │ │ │  <code class="inline">rem</code> that gives the remainder after division, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">74&gt; </span><span class="mi">2004</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">400</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="mi">4</span></code></pre><p>So instead of writing:</p><pre><code class="makeup erlang" translate="no"><span class="nf">trunc</span><span class="p" data-group-id="7685875661-1">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="7685875661-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="mi">4</span></code></pre><p>So instead of writing:</p><pre><code class="makeup erlang" translate="no"><span class="nf">trunc</span><span class="p" data-group-id="9131910910-1">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="9131910910-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">leap</span><span class="p">;</span></code></pre><p>it can be written:</p><pre><code class="makeup erlang" translate="no"><span class="n">Year</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">leap</span><span class="p">;</span></code></pre><p>There are many other BIFs such as <code class="inline">trunc</code>. Only a few BIFs can be used in
│ │ │ │  guards, and you cannot use functions you have defined yourself in guards. (see
│ │ │ │  <a href="../../../lib/../system/doc/html/expressions.xhtml">Guard Sequences</a>) (For advanced readers: This is to
│ │ │ │  ensure that guards do not have side effects.) Let us play with a few of these
│ │ │ │ -functions in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">75&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="9516409071-1">(</span><span class="mf">5.6</span><span class="p" data-group-id="9516409071-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +functions in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">75&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="3233329516-1">(</span><span class="mf">5.6</span><span class="p" data-group-id="3233329516-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">5</span><span class="gp unselectable">
│ │ │ │ -76&gt; </span><span class="nf">round</span><span class="p" data-group-id="9516409071-2">(</span><span class="mf">5.6</span><span class="p" data-group-id="9516409071-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +76&gt; </span><span class="nf">round</span><span class="p" data-group-id="3233329516-2">(</span><span class="mf">5.6</span><span class="p" data-group-id="3233329516-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">6</span><span class="gp unselectable">
│ │ │ │ -77&gt; </span><span class="nf">length</span><span class="p" data-group-id="9516409071-3">(</span><span class="p" data-group-id="9516409071-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="9516409071-4">]</span><span class="p" data-group-id="9516409071-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +77&gt; </span><span class="nf">length</span><span class="p" data-group-id="3233329516-3">(</span><span class="p" data-group-id="3233329516-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3233329516-4">]</span><span class="p" data-group-id="3233329516-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ │ -78&gt; </span><span class="nf">float</span><span class="p" data-group-id="9516409071-5">(</span><span class="mi">5</span><span class="p" data-group-id="9516409071-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +78&gt; </span><span class="nf">float</span><span class="p" data-group-id="3233329516-5">(</span><span class="mi">5</span><span class="p" data-group-id="3233329516-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mf">5.0</span><span class="gp unselectable">
│ │ │ │ -79&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="9516409071-6">(</span><span class="ss">hello</span><span class="p" data-group-id="9516409071-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +79&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="3233329516-6">(</span><span class="ss">hello</span><span class="p" data-group-id="3233329516-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -80&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="9516409071-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="9516409071-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +80&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="3233329516-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="3233329516-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │ -81&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="9516409071-8">(</span><span class="p" data-group-id="9516409071-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9516409071-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="9516409071-10">}</span><span class="p" data-group-id="9516409071-9">}</span><span class="p" data-group-id="9516409071-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +81&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="3233329516-8">(</span><span class="p" data-group-id="3233329516-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3233329516-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="3233329516-10">}</span><span class="p" data-group-id="3233329516-9">}</span><span class="p" data-group-id="3233329516-8">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -82&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="9516409071-11">(</span><span class="p" data-group-id="9516409071-12">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9516409071-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="9516409071-13">}</span><span class="p" data-group-id="9516409071-12">]</span><span class="p" data-group-id="9516409071-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +82&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="3233329516-11">(</span><span class="p" data-group-id="3233329516-12">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3233329516-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="3233329516-13">}</span><span class="p" data-group-id="3233329516-12">]</span><span class="p" data-group-id="3233329516-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span></code></pre><p>All of these can be used in guards. Now for some BIFs that cannot be used in
│ │ │ │ -guards:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">83&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="7990039634-1">(</span><span class="ss">hello</span><span class="p" data-group-id="7990039634-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +guards:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">83&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="3410540877-1">(</span><span class="ss">hello</span><span class="p" data-group-id="3410540877-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ │ -84&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="7990039634-2">(</span><span class="s">&quot;goodbye&quot;</span><span class="p" data-group-id="7990039634-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +84&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="3410540877-2">(</span><span class="s">&quot;goodbye&quot;</span><span class="p" data-group-id="3410540877-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">goodbye</span><span class="gp unselectable">
│ │ │ │ -85&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="7990039634-3">(</span><span class="mi">22</span><span class="p" data-group-id="7990039634-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +85&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="3410540877-3">(</span><span class="mi">22</span><span class="p" data-group-id="3410540877-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;22&quot;</span></code></pre><p>These three BIFs do conversions that would be difficult (or impossible) to do in
│ │ │ │  Erlang.</p><h2 id="higher-order-functions-funs" class="section-heading">
│ │ │ │    <a href="#higher-order-functions-funs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Higher-Order Functions (Funs)</span>
│ │ │ │  </h2>
│ │ │ │  <p>Erlang, like most modern functional programming languages, has higher-order
│ │ │ │ -functions. Here is an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">86&gt; </span><span class="n">Xf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3010118836-1">(</span><span class="n">X</span><span class="p" data-group-id="3010118836-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +functions. Here is an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">86&gt; </span><span class="n">Xf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="9068017574-1">(</span><span class="n">X</span><span class="p" data-group-id="9068017574-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">5.123085357</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -87&gt; </span><span class="n">Xf</span><span class="p" data-group-id="3010118836-2">(</span><span class="mi">5</span><span class="p" data-group-id="3010118836-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +87&gt; </span><span class="n">Xf</span><span class="p" data-group-id="9068017574-2">(</span><span class="mi">5</span><span class="p" data-group-id="9068017574-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">10</span></code></pre><p>Here is defined a function that doubles the value of a number and assigned this
│ │ │ │  function to a variable. Thus <code class="inline">Xf(5)</code> returns value 10. Two useful functions when
│ │ │ │ -working with lists are <code class="inline">foreach</code> and <code class="inline">map</code>, which are defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="9909964457-1">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9909964457-2">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="9909964457-2">]</span><span class="p" data-group-id="9909964457-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Fun</span><span class="p" data-group-id="9909964457-3">(</span><span class="n">First</span><span class="p" data-group-id="9909964457-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="9909964457-4">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9909964457-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">foreach</span><span class="p" data-group-id="9909964457-5">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9909964457-6">[</span><span class="p" data-group-id="9909964457-6">]</span><span class="p" data-group-id="9909964457-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +working with lists are <code class="inline">foreach</code> and <code class="inline">map</code>, which are defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="7552225584-1">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7552225584-2">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="7552225584-2">]</span><span class="p" data-group-id="7552225584-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Fun</span><span class="p" data-group-id="7552225584-3">(</span><span class="n">First</span><span class="p" data-group-id="7552225584-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="7552225584-4">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="7552225584-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">foreach</span><span class="p" data-group-id="7552225584-5">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7552225584-6">[</span><span class="p" data-group-id="7552225584-6">]</span><span class="p" data-group-id="7552225584-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="9909964457-7">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9909964457-8">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="9909964457-8">]</span><span class="p" data-group-id="9909964457-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9909964457-9">[</span><span class="n">Fun</span><span class="p" data-group-id="9909964457-10">(</span><span class="n">First</span><span class="p" data-group-id="9909964457-10">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="9909964457-11">(</span><span class="n">Fun</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="9909964457-11">)</span><span class="p" data-group-id="9909964457-9">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="9909964457-12">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9909964457-13">[</span><span class="p" data-group-id="9909964457-13">]</span><span class="p" data-group-id="9909964457-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9909964457-14">[</span><span class="p" data-group-id="9909964457-14">]</span><span class="p">.</span></code></pre><p>These two functions are provided in the standard module <code class="inline">lists</code>. <code class="inline">foreach</code> takes
│ │ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="7552225584-7">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7552225584-8">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="7552225584-8">]</span><span class="p" data-group-id="7552225584-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7552225584-9">[</span><span class="n">Fun</span><span class="p" data-group-id="7552225584-10">(</span><span class="n">First</span><span class="p" data-group-id="7552225584-10">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="7552225584-11">(</span><span class="n">Fun</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="7552225584-11">)</span><span class="p" data-group-id="7552225584-9">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="7552225584-12">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7552225584-13">[</span><span class="p" data-group-id="7552225584-13">]</span><span class="p" data-group-id="7552225584-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7552225584-14">[</span><span class="p" data-group-id="7552225584-14">]</span><span class="p">.</span></code></pre><p>These two functions are provided in the standard module <code class="inline">lists</code>. <code class="inline">foreach</code> takes
│ │ │ │  a list and applies a fun to every element in the list. <code class="inline">map</code> creates a new list
│ │ │ │  by applying a fun to every element in a list. Going back to the shell, <code class="inline">map</code> is
│ │ │ │ -used and a fun to add 3 to every element of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">88&gt; </span><span class="n">Add_3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4807047674-1">(</span><span class="n">X</span><span class="p" data-group-id="4807047674-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +used and a fun to add 3 to every element of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">88&gt; </span><span class="n">Add_3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="5051346014-1">(</span><span class="n">X</span><span class="p" data-group-id="5051346014-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">5.123085357</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -89&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="4807047674-2">(</span><span class="n">Add_3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4807047674-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4807047674-3">]</span><span class="p" data-group-id="4807047674-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4807047674-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="4807047674-4">]</span></code></pre><p>Let us (again) print the temperatures in a list of cities:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">90&gt; </span><span class="n">Print_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="5036272188-1">(</span><span class="p" data-group-id="5036272188-2">{</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="5036272188-3">}</span><span class="p" data-group-id="5036272188-2">}</span><span class="p" data-group-id="5036272188-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5036272188-4">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5036272188-5">[</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="5036272188-5">]</span><span class="p" data-group-id="5036272188-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +89&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="5051346014-2">(</span><span class="n">Add_3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5051346014-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5051346014-3">]</span><span class="p" data-group-id="5051346014-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5051346014-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5051346014-4">]</span></code></pre><p>Let us (again) print the temperatures in a list of cities:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">90&gt; </span><span class="n">Print_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="5927389181-1">(</span><span class="p" data-group-id="5927389181-2">{</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="5927389181-3">}</span><span class="p" data-group-id="5927389181-2">}</span><span class="p" data-group-id="5927389181-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5927389181-4">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5927389181-5">[</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="5927389181-5">]</span><span class="p" data-group-id="5927389181-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">5.123085357</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -91&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="5036272188-6">(</span><span class="n">Print_City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-7">[</span><span class="p" data-group-id="5036272188-8">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-9">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="5036272188-9">}</span><span class="p" data-group-id="5036272188-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-10">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="5036272188-11">}</span><span class="p" data-group-id="5036272188-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5036272188-12">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="5036272188-13">}</span><span class="p" data-group-id="5036272188-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-14">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-15">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="5036272188-15">}</span><span class="p" data-group-id="5036272188-14">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-16">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5036272188-17">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="5036272188-17">}</span><span class="p" data-group-id="5036272188-16">}</span><span class="p" data-group-id="5036272188-7">]</span><span class="p" data-group-id="5036272188-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +91&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="5927389181-6">(</span><span class="n">Print_City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-7">[</span><span class="p" data-group-id="5927389181-8">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-9">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="5927389181-9">}</span><span class="p" data-group-id="5927389181-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-10">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="5927389181-11">}</span><span class="p" data-group-id="5927389181-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5927389181-12">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="5927389181-13">}</span><span class="p" data-group-id="5927389181-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-14">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-15">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="5927389181-15">}</span><span class="p" data-group-id="5927389181-14">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-16">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927389181-17">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="5927389181-17">}</span><span class="p" data-group-id="5927389181-16">}</span><span class="p" data-group-id="5927389181-7">]</span><span class="p" data-group-id="5927389181-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="ss">c</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="w">
│ │ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="ss">f</span><span class="w"> </span><span class="mi">70</span><span class="w">
│ │ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="ss">c</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="w">
│ │ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="ss">f</span><span class="w"> </span><span class="mi">28</span><span class="w">
│ │ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="ss">f</span><span class="w"> </span><span class="mi">36</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>Let us now define a fun that can be used to go through a list of cities and
│ │ │ │ -temperatures and transform them all to Celsius.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2407371551-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="2407371551-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +temperatures and transform them all to Celsius.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1022125673-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="1022125673-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2407371551-2">(</span><span class="p" data-group-id="2407371551-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2407371551-3">]</span><span class="p" data-group-id="2407371551-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1022125673-2">(</span><span class="p" data-group-id="1022125673-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1022125673-3">]</span><span class="p" data-group-id="1022125673-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2407371551-4">(</span><span class="p" data-group-id="2407371551-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2407371551-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2407371551-6">}</span><span class="p" data-group-id="2407371551-5">}</span><span class="p" data-group-id="2407371551-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2407371551-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2407371551-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="2407371551-9">(</span><span class="p" data-group-id="2407371551-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="2407371551-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="2407371551-9">)</span><span class="p" data-group-id="2407371551-8">}</span><span class="p" data-group-id="2407371551-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2407371551-11">(</span><span class="p" data-group-id="2407371551-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2407371551-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2407371551-13">}</span><span class="p" data-group-id="2407371551-12">}</span><span class="p" data-group-id="2407371551-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2407371551-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2407371551-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2407371551-15">}</span><span class="p" data-group-id="2407371551-14">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2407371551-16">(</span><span class="n">List</span><span class="p" data-group-id="2407371551-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="2407371551-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2407371551-17">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">92&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="6124696044-1">(</span><span class="p" data-group-id="6124696044-2">[</span><span class="p" data-group-id="6124696044-3">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-4">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="6124696044-4">}</span><span class="p" data-group-id="6124696044-3">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-5">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="6124696044-6">}</span><span class="p" data-group-id="6124696044-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6124696044-7">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="6124696044-8">}</span><span class="p" data-group-id="6124696044-7">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="6124696044-10">}</span><span class="p" data-group-id="6124696044-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-11">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6124696044-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="6124696044-12">}</span><span class="p" data-group-id="6124696044-11">}</span><span class="p" data-group-id="6124696044-2">]</span><span class="p" data-group-id="6124696044-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6124696044-13">[</span><span class="p" data-group-id="6124696044-14">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="6124696044-15">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="6124696044-15">}</span><span class="p" data-group-id="6124696044-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6124696044-16">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="6124696044-17">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="6124696044-17">}</span><span class="p" data-group-id="6124696044-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6124696044-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="6124696044-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="6124696044-19">}</span><span class="p" data-group-id="6124696044-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6124696044-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="6124696044-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="6124696044-21">}</span><span class="p" data-group-id="6124696044-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6124696044-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="6124696044-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6124696044-23">}</span><span class="p" data-group-id="6124696044-22">}</span><span class="p" data-group-id="6124696044-13">]</span></code></pre><p>The <code class="inline">convert_to_c</code> function is the same as before, but here it is used as a fun:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="2268910651-1">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2268910651-1">)</span></code></pre><p>When a function defined elsewhere is used as a fun, it can be referred to as
│ │ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="1022125673-4">(</span><span class="p" data-group-id="1022125673-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1022125673-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1022125673-6">}</span><span class="p" data-group-id="1022125673-5">}</span><span class="p" data-group-id="1022125673-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1022125673-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1022125673-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="1022125673-9">(</span><span class="p" data-group-id="1022125673-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="1022125673-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="1022125673-9">)</span><span class="p" data-group-id="1022125673-8">}</span><span class="p" data-group-id="1022125673-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="1022125673-11">(</span><span class="p" data-group-id="1022125673-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1022125673-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1022125673-13">}</span><span class="p" data-group-id="1022125673-12">}</span><span class="p" data-group-id="1022125673-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1022125673-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1022125673-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1022125673-15">}</span><span class="p" data-group-id="1022125673-14">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="1022125673-16">(</span><span class="n">List</span><span class="p" data-group-id="1022125673-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="1022125673-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="1022125673-17">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">92&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4397069586-1">(</span><span class="p" data-group-id="4397069586-2">[</span><span class="p" data-group-id="4397069586-3">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-4">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="4397069586-4">}</span><span class="p" data-group-id="4397069586-3">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-5">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="4397069586-6">}</span><span class="p" data-group-id="4397069586-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4397069586-7">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="4397069586-8">}</span><span class="p" data-group-id="4397069586-7">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="4397069586-10">}</span><span class="p" data-group-id="4397069586-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-11">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4397069586-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="4397069586-12">}</span><span class="p" data-group-id="4397069586-11">}</span><span class="p" data-group-id="4397069586-2">]</span><span class="p" data-group-id="4397069586-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4397069586-13">[</span><span class="p" data-group-id="4397069586-14">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="4397069586-15">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="4397069586-15">}</span><span class="p" data-group-id="4397069586-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4397069586-16">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="4397069586-17">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="4397069586-17">}</span><span class="p" data-group-id="4397069586-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4397069586-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="4397069586-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="4397069586-19">}</span><span class="p" data-group-id="4397069586-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4397069586-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="4397069586-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="4397069586-21">}</span><span class="p" data-group-id="4397069586-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4397069586-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="4397069586-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4397069586-23">}</span><span class="p" data-group-id="4397069586-22">}</span><span class="p" data-group-id="4397069586-13">]</span></code></pre><p>The <code class="inline">convert_to_c</code> function is the same as before, but here it is used as a fun:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="3245093504-1">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="3245093504-1">)</span></code></pre><p>When a function defined elsewhere is used as a fun, it can be referred to as
│ │ │ │  <code class="inline">Function/Arity</code> (remember that <code class="inline">Arity</code> = number of arguments). So in the
│ │ │ │  <code class="inline">map</code>-call <code class="inline">lists:map(fun convert_to_c/1, List)</code> is written. As shown,
│ │ │ │  <code class="inline">convert_list_to_c</code> becomes much shorter and easier to understand.</p><p>The standard module <code class="inline">lists</code> also contains a function <code class="inline">sort(Fun, List)</code> where
│ │ │ │  <code class="inline">Fun</code> is a fun with two arguments. This fun returns <code class="inline">true</code> if the first argument
│ │ │ │  is less than the second argument, or else <code class="inline">false</code>. Sorting is added to the
│ │ │ │ -<code class="inline">convert_list_to_c</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3983966792-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="3983966792-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">convert_list_to_c</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9253720077-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="9253720077-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3983966792-2">(</span><span class="p" data-group-id="3983966792-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3983966792-3">]</span><span class="p" data-group-id="3983966792-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9253720077-2">(</span><span class="p" data-group-id="9253720077-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9253720077-3">]</span><span class="p" data-group-id="9253720077-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="3983966792-4">(</span><span class="p" data-group-id="3983966792-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3983966792-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="3983966792-6">}</span><span class="p" data-group-id="3983966792-5">}</span><span class="p" data-group-id="3983966792-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3983966792-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3983966792-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="3983966792-9">(</span><span class="p" data-group-id="3983966792-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="3983966792-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="3983966792-9">)</span><span class="p" data-group-id="3983966792-8">}</span><span class="p" data-group-id="3983966792-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="3983966792-11">(</span><span class="p" data-group-id="3983966792-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3983966792-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="3983966792-13">}</span><span class="p" data-group-id="3983966792-12">}</span><span class="p" data-group-id="3983966792-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3983966792-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3983966792-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="3983966792-15">}</span><span class="p" data-group-id="3983966792-14">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3983966792-16">(</span><span class="n">List</span><span class="p" data-group-id="3983966792-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">New_list</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="3983966792-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="3983966792-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="3983966792-18">(</span><span class="nf">fun</span><span class="p" data-group-id="3983966792-19">(</span><span class="p" data-group-id="3983966792-20">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3983966792-21">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="3983966792-21">}</span><span class="p" data-group-id="3983966792-20">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3983966792-22">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3983966792-23">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="3983966792-23">}</span><span class="p" data-group-id="3983966792-22">}</span><span class="p" data-group-id="3983966792-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                       </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">New_list</span><span class="p" data-group-id="3983966792-18">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">93&gt; </span><span class="nf">c</span><span class="p" data-group-id="9866361174-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="9866361174-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9866361174-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut13</span><span class="p" data-group-id="9866361174-2">}</span><span class="gp unselectable">
│ │ │ │ -94&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9866361174-3">(</span><span class="p" data-group-id="9866361174-4">[</span><span class="p" data-group-id="9866361174-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="9866361174-6">}</span><span class="p" data-group-id="9866361174-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="9866361174-8">}</span><span class="p" data-group-id="9866361174-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9866361174-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="9866361174-10">}</span><span class="p" data-group-id="9866361174-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="9866361174-12">}</span><span class="p" data-group-id="9866361174-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9866361174-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="9866361174-14">}</span><span class="p" data-group-id="9866361174-13">}</span><span class="p" data-group-id="9866361174-4">]</span><span class="p" data-group-id="9866361174-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9866361174-15">[</span><span class="p" data-group-id="9866361174-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="9866361174-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="9866361174-17">}</span><span class="p" data-group-id="9866361174-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="9866361174-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="9866361174-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="9866361174-19">}</span><span class="p" data-group-id="9866361174-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="9866361174-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="9866361174-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="9866361174-21">}</span><span class="p" data-group-id="9866361174-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="9866361174-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="9866361174-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9866361174-23">}</span><span class="p" data-group-id="9866361174-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="9866361174-24">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="9866361174-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="9866361174-25">}</span><span class="p" data-group-id="9866361174-24">}</span><span class="p" data-group-id="9866361174-15">]</span></code></pre><p>In <code class="inline">sort</code> the fun is used:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="p" data-group-id="6072494651-1">(</span><span class="p" data-group-id="6072494651-2">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6072494651-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="6072494651-3">}</span><span class="p" data-group-id="6072494651-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6072494651-4">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6072494651-5">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="6072494651-5">}</span><span class="p" data-group-id="6072494651-4">}</span><span class="p" data-group-id="6072494651-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span></code></pre><p>Here the concept of an <em>anonymous variable</em> <code class="inline">_</code> is introduced. This is simply
│ │ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="9253720077-4">(</span><span class="p" data-group-id="9253720077-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9253720077-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9253720077-6">}</span><span class="p" data-group-id="9253720077-5">}</span><span class="p" data-group-id="9253720077-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9253720077-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9253720077-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="9253720077-9">(</span><span class="p" data-group-id="9253720077-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="9253720077-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="9253720077-9">)</span><span class="p" data-group-id="9253720077-8">}</span><span class="p" data-group-id="9253720077-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="9253720077-11">(</span><span class="p" data-group-id="9253720077-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9253720077-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9253720077-13">}</span><span class="p" data-group-id="9253720077-12">}</span><span class="p" data-group-id="9253720077-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9253720077-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9253720077-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9253720077-15">}</span><span class="p" data-group-id="9253720077-14">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9253720077-16">(</span><span class="n">List</span><span class="p" data-group-id="9253720077-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">New_list</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="9253720077-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="9253720077-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="9253720077-18">(</span><span class="nf">fun</span><span class="p" data-group-id="9253720077-19">(</span><span class="p" data-group-id="9253720077-20">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9253720077-21">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="9253720077-21">}</span><span class="p" data-group-id="9253720077-20">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9253720077-22">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9253720077-23">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="9253720077-23">}</span><span class="p" data-group-id="9253720077-22">}</span><span class="p" data-group-id="9253720077-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                       </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">New_list</span><span class="p" data-group-id="9253720077-18">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">93&gt; </span><span class="nf">c</span><span class="p" data-group-id="2831592669-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="2831592669-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2831592669-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut13</span><span class="p" data-group-id="2831592669-2">}</span><span class="gp unselectable">
│ │ │ │ +94&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2831592669-3">(</span><span class="p" data-group-id="2831592669-4">[</span><span class="p" data-group-id="2831592669-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="2831592669-6">}</span><span class="p" data-group-id="2831592669-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="2831592669-8">}</span><span class="p" data-group-id="2831592669-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2831592669-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="2831592669-10">}</span><span class="p" data-group-id="2831592669-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="2831592669-12">}</span><span class="p" data-group-id="2831592669-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2831592669-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="2831592669-14">}</span><span class="p" data-group-id="2831592669-13">}</span><span class="p" data-group-id="2831592669-4">]</span><span class="p" data-group-id="2831592669-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2831592669-15">[</span><span class="p" data-group-id="2831592669-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="2831592669-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="2831592669-17">}</span><span class="p" data-group-id="2831592669-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2831592669-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="2831592669-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="2831592669-19">}</span><span class="p" data-group-id="2831592669-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2831592669-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="2831592669-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="2831592669-21">}</span><span class="p" data-group-id="2831592669-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2831592669-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="2831592669-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2831592669-23">}</span><span class="p" data-group-id="2831592669-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2831592669-24">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="2831592669-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="2831592669-25">}</span><span class="p" data-group-id="2831592669-24">}</span><span class="p" data-group-id="2831592669-15">]</span></code></pre><p>In <code class="inline">sort</code> the fun is used:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="p" data-group-id="0797514054-1">(</span><span class="p" data-group-id="0797514054-2">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0797514054-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="0797514054-3">}</span><span class="p" data-group-id="0797514054-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0797514054-4">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0797514054-5">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="0797514054-5">}</span><span class="p" data-group-id="0797514054-4">}</span><span class="p" data-group-id="0797514054-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span></code></pre><p>Here the concept of an <em>anonymous variable</em> <code class="inline">_</code> is introduced. This is simply
│ │ │ │  shorthand for a variable that gets a value, but the value is ignored. This can
│ │ │ │  be used anywhere suitable, not just in funs. <code class="inline">Temp1 &lt; Temp2</code> returns <code class="inline">true</code> if
│ │ │ │  <code class="inline">Temp1</code> is less than <code class="inline">Temp2</code>.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/robustness.xhtml
│ │ │ │ @@ -33,68 +33,68 @@
│ │ │ │  </h2>
│ │ │ │  <p>Before improving the messenger program, let us look at some general principles,
│ │ │ │  using the ping pong program as an example. Recall that when &quot;ping&quot; finishes, it
│ │ │ │  tells &quot;pong&quot; that it has done so by sending the atom <code class="inline">finished</code> as a message to
│ │ │ │  &quot;pong&quot; so that &quot;pong&quot; can also finish. Another way to let &quot;pong&quot; finish is to
│ │ │ │  make &quot;pong&quot; exit if it does not receive a message from ping within a certain
│ │ │ │  time. This can be done by adding a <em>time-out</em> to <code class="inline">pong</code> as shown in the
│ │ │ │ -following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1088114027-1">(</span><span class="ss">tut19</span><span class="p" data-group-id="1088114027-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4685177356-1">(</span><span class="ss">tut19</span><span class="p" data-group-id="4685177356-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1088114027-2">(</span><span class="p" data-group-id="1088114027-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1088114027-3">]</span><span class="p" data-group-id="1088114027-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4685177356-2">(</span><span class="p" data-group-id="4685177356-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="4685177356-3">]</span><span class="p" data-group-id="4685177356-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="1088114027-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1088114027-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1088114027-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1088114027-6">[</span><span class="p" data-group-id="1088114027-6">]</span><span class="p" data-group-id="1088114027-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="4685177356-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="4685177356-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4685177356-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4685177356-6">[</span><span class="p" data-group-id="4685177356-6">]</span><span class="p" data-group-id="4685177356-5">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="1088114027-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1088114027-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1088114027-8">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1088114027-8">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1088114027-9">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1088114027-10">(</span><span class="p" data-group-id="1088114027-10">)</span><span class="p" data-group-id="1088114027-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="4685177356-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="4685177356-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4685177356-8">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="4685177356-8">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4685177356-9">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4685177356-10">(</span><span class="p" data-group-id="4685177356-10">)</span><span class="p" data-group-id="4685177356-9">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1088114027-11">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1088114027-12">[</span><span class="p" data-group-id="1088114027-12">]</span><span class="p" data-group-id="1088114027-11">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4685177356-11">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4685177356-12">[</span><span class="p" data-group-id="4685177356-12">]</span><span class="p" data-group-id="4685177356-11">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="1088114027-13">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1088114027-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="4685177356-13">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="4685177356-13">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="1088114027-14">(</span><span class="p" data-group-id="1088114027-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="4685177356-14">(</span><span class="p" data-group-id="4685177356-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1088114027-15">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="1088114027-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1088114027-16">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1088114027-17">[</span><span class="p" data-group-id="1088114027-17">]</span><span class="p" data-group-id="1088114027-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="4685177356-15">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="4685177356-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4685177356-16">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4685177356-17">[</span><span class="p" data-group-id="4685177356-17">]</span><span class="p" data-group-id="4685177356-16">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="1088114027-18">(</span><span class="p" data-group-id="1088114027-18">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="4685177356-18">(</span><span class="p" data-group-id="4685177356-18">)</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1088114027-19">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1088114027-20">[</span><span class="p" data-group-id="1088114027-20">]</span><span class="p" data-group-id="1088114027-19">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4685177356-19">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4685177356-20">[</span><span class="p" data-group-id="4685177356-20">]</span><span class="p" data-group-id="4685177356-19">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_pong</span><span class="p" data-group-id="1088114027-21">(</span><span class="p" data-group-id="1088114027-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="1088114027-22">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1088114027-23">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1088114027-24">[</span><span class="p" data-group-id="1088114027-24">]</span><span class="p" data-group-id="1088114027-23">)</span><span class="p" data-group-id="1088114027-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_pong</span><span class="p" data-group-id="4685177356-21">(</span><span class="p" data-group-id="4685177356-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="4685177356-22">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="4685177356-23">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4685177356-24">[</span><span class="p" data-group-id="4685177356-24">]</span><span class="p" data-group-id="4685177356-23">)</span><span class="p" data-group-id="4685177356-22">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_ping</span><span class="p" data-group-id="1088114027-25">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="1088114027-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="1088114027-26">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1088114027-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1088114027-27">]</span><span class="p" data-group-id="1088114027-26">)</span><span class="p">.</span></code></pre><p>After this is compiled and the file <code class="inline">tut19.beam</code> is copied to the necessary
│ │ │ │ +</span><span class="nf">start_ping</span><span class="p" data-group-id="4685177356-25">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="4685177356-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="4685177356-26">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4685177356-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="4685177356-27">]</span><span class="p" data-group-id="4685177356-26">)</span><span class="p">.</span></code></pre><p>After this is compiled and the file <code class="inline">tut19.beam</code> is copied to the necessary
│ │ │ │  directories, the following is seen on (pong@kosken):</p><pre><code class="text">(pong@kosken)1&gt; tut19:start_pong().
│ │ │ │  true
│ │ │ │  Pong received ping
│ │ │ │  Pong received ping
│ │ │ │  Pong received ping
│ │ │ │  Pong timed out</code></pre><p>And the following is seen on (ping@gollum):</p><pre><code class="text">(ping@gollum)1&gt; tut19:start_ping(pong@kosken).
│ │ │ │  &lt;0.36.0&gt;
│ │ │ │  Ping received pong
│ │ │ │  Ping received pong
│ │ │ │  Ping received pong
│ │ │ │ -ping finished</code></pre><p>The time-out is set in:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pong</span><span class="p" data-group-id="1923652363-1">(</span><span class="p" data-group-id="1923652363-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +ping finished</code></pre><p>The time-out is set in:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pong</span><span class="p" data-group-id="9346855580-1">(</span><span class="p" data-group-id="9346855580-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1923652363-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="1923652363-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1923652363-3">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1923652363-4">[</span><span class="p" data-group-id="1923652363-4">]</span><span class="p" data-group-id="1923652363-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="9346855580-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="9346855580-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9346855580-3">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9346855580-4">[</span><span class="p" data-group-id="9346855580-4">]</span><span class="p" data-group-id="9346855580-3">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="1923652363-5">(</span><span class="p" data-group-id="1923652363-5">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="9346855580-5">(</span><span class="p" data-group-id="9346855580-5">)</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1923652363-6">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1923652363-7">[</span><span class="p" data-group-id="1923652363-7">]</span><span class="p" data-group-id="1923652363-6">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9346855580-6">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9346855580-7">[</span><span class="p" data-group-id="9346855580-7">]</span><span class="p" data-group-id="9346855580-6">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The time-out (<code class="inline">after 5000</code>) is started when <code class="inline">receive</code> is entered. The time-out
│ │ │ │  is canceled if <code class="inline">{ping,Ping_PID}</code> is received. If <code class="inline">{ping,Ping_PID}</code> is not
│ │ │ │  received, the actions following the time-out are done after 5000 milliseconds.
│ │ │ │  <code class="inline">after</code> must be last in the <code class="inline">receive</code>, that is, preceded by all other message
│ │ │ │  reception specifications in the <code class="inline">receive</code>. It is also possible to call a
│ │ │ │ -function that returned an integer for the time-out:</p><pre><code class="makeup erlang" translate="no"><span class="k">after</span><span class="w"> </span><span class="nf">pong_timeout</span><span class="p" data-group-id="6123177273-1">(</span><span class="p" data-group-id="6123177273-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>In general, there are better ways than using time-outs to supervise parts of a
│ │ │ │ +function that returned an integer for the time-out:</p><pre><code class="makeup erlang" translate="no"><span class="k">after</span><span class="w"> </span><span class="nf">pong_timeout</span><span class="p" data-group-id="2050840613-1">(</span><span class="p" data-group-id="2050840613-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>In general, there are better ways than using time-outs to supervise parts of a
│ │ │ │  distributed Erlang system. Time-outs are usually appropriate to supervise
│ │ │ │  external events, for example, if you have expected a message from some external
│ │ │ │  system within a specified time. For example, a time-out can be used to log a
│ │ │ │  user out of the messenger system if they have not accessed it for, say, ten
│ │ │ │  minutes.</p><h2 id="error-handling" class="section-heading">
│ │ │ │    <a href="#error-handling" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │ @@ -114,96 +114,96 @@
│ │ │ │  something called a <em>signal</em> to all the processes it has links to.</p><p>The signal carries information about the pid it was sent from and the exit
│ │ │ │  reason.</p><p>The default behaviour of a process that receives a normal exit is to ignore the
│ │ │ │  signal.</p><p>The default behaviour in the two other cases (that is, abnormal exit) above is
│ │ │ │  to:</p><ul><li>Bypass all messages to the receiving process.</li><li>Kill the receiving process.</li><li>Propagate the same error signal to the links of the killed process.</li></ul><p>In this way you can connect all processes in a transaction together using links.
│ │ │ │  If one of the processes exits abnormally, all the processes in the transaction
│ │ │ │  are killed. As it is often wanted to create a process and link to it at the same
│ │ │ │  time, there is a special BIF, <a href="../../../lib/../erts/doc/html/erlang.html#spawn_link/1">spawn_link</a> that does the
│ │ │ │ -same as <code class="inline">spawn</code>, but also creates a link to the spawned process.</p><p>Now an example of the ping pong example using links to terminate &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3174822415-1">(</span><span class="ss">tut20</span><span class="p" data-group-id="3174822415-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +same as <code class="inline">spawn</code>, but also creates a link to the spawned process.</p><p>Now an example of the ping pong example using links to terminate &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1512994209-1">(</span><span class="ss">tut20</span><span class="p" data-group-id="1512994209-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3174822415-2">(</span><span class="p" data-group-id="3174822415-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3174822415-3">]</span><span class="p" data-group-id="3174822415-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1512994209-2">(</span><span class="p" data-group-id="1512994209-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1512994209-3">]</span><span class="p" data-group-id="1512994209-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="3174822415-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="3174822415-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">link</span><span class="p" data-group-id="3174822415-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="3174822415-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="3174822415-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="3174822415-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="1512994209-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="1512994209-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">link</span><span class="p" data-group-id="1512994209-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="1512994209-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="1512994209-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="1512994209-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="3174822415-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="3174822415-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="3174822415-8">(</span><span class="ss">ping</span><span class="p" data-group-id="3174822415-8">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="1512994209-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="1512994209-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="1512994209-8">(</span><span class="ss">ping</span><span class="p" data-group-id="1512994209-8">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="3174822415-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="3174822415-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3174822415-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3174822415-11">(</span><span class="p" data-group-id="3174822415-11">)</span><span class="p" data-group-id="3174822415-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="1512994209-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="1512994209-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1512994209-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1512994209-11">(</span><span class="p" data-group-id="1512994209-11">)</span><span class="p" data-group-id="1512994209-10">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3174822415-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3174822415-13">[</span><span class="p" data-group-id="3174822415-13">]</span><span class="p" data-group-id="3174822415-12">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1512994209-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512994209-13">[</span><span class="p" data-group-id="1512994209-13">]</span><span class="p" data-group-id="1512994209-12">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="3174822415-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="3174822415-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="1512994209-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="1512994209-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="3174822415-15">(</span><span class="p" data-group-id="3174822415-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="1512994209-15">(</span><span class="p" data-group-id="1512994209-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="3174822415-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="3174822415-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3174822415-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3174822415-18">[</span><span class="p" data-group-id="3174822415-18">]</span><span class="p" data-group-id="3174822415-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="1512994209-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="1512994209-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1512994209-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512994209-18">[</span><span class="p" data-group-id="1512994209-18">]</span><span class="p" data-group-id="1512994209-17">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="3174822415-19">(</span><span class="p" data-group-id="3174822415-19">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="1512994209-19">(</span><span class="p" data-group-id="1512994209-19">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="3174822415-20">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="3174822415-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="3174822415-21">(</span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3174822415-22">[</span><span class="p" data-group-id="3174822415-22">]</span><span class="p" data-group-id="3174822415-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="3174822415-23">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3174822415-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="3174822415-24">]</span><span class="p" data-group-id="3174822415-23">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)3&gt; tut20:start(s2@kosken).
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1512994209-20">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="1512994209-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1512994209-21">(</span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512994209-22">[</span><span class="p" data-group-id="1512994209-22">]</span><span class="p" data-group-id="1512994209-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1512994209-23">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512994209-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="1512994209-24">]</span><span class="p" data-group-id="1512994209-23">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)3&gt; tut20:start(s2@kosken).
│ │ │ │  Pong received ping
│ │ │ │  &lt;3820.41.0&gt;
│ │ │ │  Ping received pong
│ │ │ │  Pong received ping
│ │ │ │  Ping received pong
│ │ │ │  Pong received ping
│ │ │ │  Ping received pong</code></pre><p>This is a slight modification of the ping pong program where both processes are
│ │ │ │  spawned from the same <code class="inline">start/1</code> function, and the &quot;ping&quot; process can be spawned
│ │ │ │  on a separate node. Notice the use of the <code class="inline">link</code> BIF. &quot;Ping&quot; calls
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit(ping)</code></a> when it finishes and this causes an exit signal to be
│ │ │ │  sent to &quot;pong&quot;, which also terminates.</p><p>It is possible to modify the default behaviour of a process so that it does not
│ │ │ │  get killed when it receives abnormal exit signals. Instead, all signals are
│ │ │ │  turned into normal messages on the format <code class="inline">{'EXIT',FromPID,Reason}</code> and added to
│ │ │ │ -the end of the receiving process' message queue. This behaviour is set by:</p><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="7649242987-1">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="7649242987-1">)</span></code></pre><p>There are several other process flags, see <a href="../../../lib/../erts/doc/html/erlang.html#process_flag/2">erlang(3)</a>.
│ │ │ │ +the end of the receiving process' message queue. This behaviour is set by:</p><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="7358340469-1">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="7358340469-1">)</span></code></pre><p>There are several other process flags, see <a href="../../../lib/../erts/doc/html/erlang.html#process_flag/2">erlang(3)</a>.
│ │ │ │  Changing the default behaviour of a process in this way is usually not done in
│ │ │ │  standard user programs, but is left to the supervisory programs in OTP. However,
│ │ │ │ -the ping pong program is modified to illustrate exit trapping.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2502773793-1">(</span><span class="ss">tut21</span><span class="p" data-group-id="2502773793-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +the ping pong program is modified to illustrate exit trapping.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4808108521-1">(</span><span class="ss">tut21</span><span class="p" data-group-id="4808108521-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2502773793-2">(</span><span class="p" data-group-id="2502773793-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2502773793-3">]</span><span class="p" data-group-id="2502773793-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4808108521-2">(</span><span class="p" data-group-id="4808108521-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="4808108521-3">]</span><span class="p" data-group-id="4808108521-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="2502773793-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2502773793-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">link</span><span class="p" data-group-id="2502773793-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="2502773793-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="2502773793-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2502773793-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="4808108521-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="4808108521-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">link</span><span class="p" data-group-id="4808108521-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="4808108521-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="4808108521-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="4808108521-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="2502773793-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="2502773793-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="2502773793-8">(</span><span class="ss">ping</span><span class="p" data-group-id="2502773793-8">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="4808108521-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="4808108521-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="4808108521-8">(</span><span class="ss">ping</span><span class="p" data-group-id="4808108521-8">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="2502773793-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2502773793-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2502773793-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2502773793-11">(</span><span class="p" data-group-id="2502773793-11">)</span><span class="p" data-group-id="2502773793-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="4808108521-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="4808108521-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4808108521-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4808108521-11">(</span><span class="p" data-group-id="4808108521-11">)</span><span class="p" data-group-id="4808108521-10">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2502773793-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2502773793-13">[</span><span class="p" data-group-id="2502773793-13">]</span><span class="p" data-group-id="2502773793-12">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4808108521-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4808108521-13">[</span><span class="p" data-group-id="4808108521-13">]</span><span class="p" data-group-id="4808108521-12">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="2502773793-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2502773793-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="4808108521-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="4808108521-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="2502773793-15">(</span><span class="p" data-group-id="2502773793-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="2502773793-16">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2502773793-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">pong1</span><span class="p" data-group-id="2502773793-17">(</span><span class="p" data-group-id="2502773793-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="4808108521-15">(</span><span class="p" data-group-id="4808108521-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="4808108521-16">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="4808108521-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">pong1</span><span class="p" data-group-id="4808108521-17">(</span><span class="p" data-group-id="4808108521-17">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong1</span><span class="p" data-group-id="2502773793-18">(</span><span class="p" data-group-id="2502773793-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">pong1</span><span class="p" data-group-id="4808108521-18">(</span><span class="p" data-group-id="4808108521-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="2502773793-19">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="2502773793-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2502773793-20">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2502773793-21">[</span><span class="p" data-group-id="2502773793-21">]</span><span class="p" data-group-id="2502773793-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="4808108521-19">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="4808108521-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4808108521-20">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4808108521-21">[</span><span class="p" data-group-id="4808108521-21">]</span><span class="p" data-group-id="4808108521-20">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong1</span><span class="p" data-group-id="2502773793-22">(</span><span class="p" data-group-id="2502773793-22">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="2502773793-23">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2502773793-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2502773793-24">(</span><span class="s">&quot;pong exiting, got </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2502773793-25">[</span><span class="p" data-group-id="2502773793-26">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2502773793-26">}</span><span class="p" data-group-id="2502773793-25">]</span><span class="p" data-group-id="2502773793-24">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong1</span><span class="p" data-group-id="4808108521-22">(</span><span class="p" data-group-id="4808108521-22">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="4808108521-23">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="4808108521-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4808108521-24">(</span><span class="s">&quot;pong exiting, got </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4808108521-25">[</span><span class="p" data-group-id="4808108521-26">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="4808108521-26">}</span><span class="p" data-group-id="4808108521-25">]</span><span class="p" data-group-id="4808108521-24">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="2502773793-27">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="2502773793-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="2502773793-28">(</span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2502773793-29">[</span><span class="p" data-group-id="2502773793-29">]</span><span class="p" data-group-id="2502773793-28">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="2502773793-30">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2502773793-31">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="2502773793-31">]</span><span class="p" data-group-id="2502773793-30">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)1&gt; tut21:start(s2@gollum).
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="4808108521-27">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="4808108521-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="4808108521-28">(</span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4808108521-29">[</span><span class="p" data-group-id="4808108521-29">]</span><span class="p" data-group-id="4808108521-28">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="4808108521-30">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4808108521-31">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="4808108521-31">]</span><span class="p" data-group-id="4808108521-30">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)1&gt; tut21:start(s2@gollum).
│ │ │ │  &lt;3820.39.0&gt;
│ │ │ │  Pong received ping
│ │ │ │  Ping received pong
│ │ │ │  Pong received ping
│ │ │ │  Ping received pong
│ │ │ │  Pong received ping
│ │ │ │  Ping received pong
│ │ │ │ @@ -256,135 +256,135 @@
│ │ │ │  </span><span class="c1">%%% Started: messenger:client(Server_Node, Name)</span><span class="w">
│ │ │ │  </span><span class="c1">%%% To client: logoff</span><span class="w">
│ │ │ │  </span><span class="c1">%%% To client: {message_to, ToName, Message}</span><span class="w">
│ │ │ │  </span><span class="c1">%%%</span><span class="w">
│ │ │ │  </span><span class="c1">%%% Configuration: change the server_node() function to return the</span><span class="w">
│ │ │ │  </span><span class="c1">%%% name of the node where the messenger server runs</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8882362864-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="8882362864-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8882362864-2">(</span><span class="p" data-group-id="8882362864-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8882362864-3">]</span><span class="p" data-group-id="8882362864-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5499184896-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="5499184896-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5499184896-2">(</span><span class="p" data-group-id="5499184896-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5499184896-3">]</span><span class="p" data-group-id="5499184896-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Change the function below to return the name of the node where the</span><span class="w">
│ │ │ │  </span><span class="c1">%%% messenger server runs</span><span class="w">
│ │ │ │ -</span><span class="nf">server_node</span><span class="p" data-group-id="8882362864-4">(</span><span class="p" data-group-id="8882362864-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_node</span><span class="p" data-group-id="5499184896-4">(</span><span class="p" data-group-id="5499184896-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">messenger@super</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% This is the server process for the &quot;messenger&quot;</span><span class="w">
│ │ │ │  </span><span class="c1">%%% the user list has the format [{ClientPid1, Name1},{ClientPid22, Name2},...]</span><span class="w">
│ │ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="8882362864-5">(</span><span class="p" data-group-id="8882362864-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="8882362864-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8882362864-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">server</span><span class="p" data-group-id="8882362864-7">(</span><span class="p" data-group-id="8882362864-8">[</span><span class="p" data-group-id="8882362864-8">]</span><span class="p" data-group-id="8882362864-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="5499184896-5">(</span><span class="p" data-group-id="5499184896-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="5499184896-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5499184896-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">server</span><span class="p" data-group-id="5499184896-7">(</span><span class="p" data-group-id="5499184896-8">[</span><span class="p" data-group-id="5499184896-8">]</span><span class="p" data-group-id="5499184896-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="8882362864-9">(</span><span class="n">User_List</span><span class="p" data-group-id="8882362864-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="5499184896-9">(</span><span class="n">User_List</span><span class="p" data-group-id="5499184896-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-10">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8882362864-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="8882362864-11">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="8882362864-12">(</span><span class="n">New_User_List</span><span class="p" data-group-id="8882362864-12">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-13">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="8882362864-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="8882362864-14">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="8882362864-15">(</span><span class="n">New_User_List</span><span class="p" data-group-id="8882362864-15">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-16">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="8882362864-17">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8882362864-18">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-19">[</span><span class="n">User_List</span><span class="p" data-group-id="8882362864-19">]</span><span class="p" data-group-id="8882362864-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="8882362864-20">(</span><span class="n">User_List</span><span class="p" data-group-id="8882362864-20">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-10">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5499184896-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="5499184896-11">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="5499184896-12">(</span><span class="n">New_User_List</span><span class="p" data-group-id="5499184896-12">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-13">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="5499184896-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="5499184896-14">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="5499184896-15">(</span><span class="n">New_User_List</span><span class="p" data-group-id="5499184896-15">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-16">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="5499184896-17">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5499184896-18">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-19">[</span><span class="n">User_List</span><span class="p" data-group-id="5499184896-19">]</span><span class="p" data-group-id="5499184896-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="5499184896-20">(</span><span class="n">User_List</span><span class="p" data-group-id="5499184896-20">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Start the server</span><span class="w">
│ │ │ │ -</span><span class="nf">start_server</span><span class="p" data-group-id="8882362864-21">(</span><span class="p" data-group-id="8882362864-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="8882362864-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="8882362864-23">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-24">[</span><span class="p" data-group-id="8882362864-24">]</span><span class="p" data-group-id="8882362864-23">)</span><span class="p" data-group-id="8882362864-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_server</span><span class="p" data-group-id="5499184896-21">(</span><span class="p" data-group-id="5499184896-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="5499184896-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="5499184896-23">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-24">[</span><span class="p" data-group-id="5499184896-24">]</span><span class="p" data-group-id="5499184896-23">)</span><span class="p" data-group-id="5499184896-22">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server adds a new user to the user list</span><span class="w">
│ │ │ │ -</span><span class="nf">server_logon</span><span class="p" data-group-id="8882362864-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_logon</span><span class="p" data-group-id="5499184896-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% check if logged on anywhere else</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="8882362864-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="5499184896-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-27">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="8882362864-27">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-27">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="5499184896-27">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │ │              </span><span class="n">User_List</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-28">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="8882362864-28">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">link</span><span class="p" data-group-id="8882362864-29">(</span><span class="n">From</span><span class="p" data-group-id="8882362864-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="8882362864-30">[</span><span class="p" data-group-id="8882362864-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8882362864-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-28">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="5499184896-28">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">link</span><span class="p" data-group-id="5499184896-29">(</span><span class="n">From</span><span class="p" data-group-id="5499184896-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="5499184896-30">[</span><span class="p" data-group-id="5499184896-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5499184896-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server deletes a user from the user list</span><span class="w">
│ │ │ │ -</span><span class="nf">server_logoff</span><span class="p" data-group-id="8882362864-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="8882362864-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-33">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">server_logoff</span><span class="p" data-group-id="5499184896-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="5499184896-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-33">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server transfers a message between user</span><span class="w">
│ │ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="8882362864-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="5499184896-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% check that the user is logged on and who he is</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8882362864-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="5499184896-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-36">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="8882362864-36">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8882362864-38">}</span><span class="p" data-group-id="8882362864-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="8882362864-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-39">)</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-36">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="5499184896-36">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5499184896-38">}</span><span class="p" data-group-id="5499184896-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="5499184896-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-39">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% If the user exists, send the message</span><span class="w">
│ │ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="8882362864-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="5499184896-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Find the receiver and send the message</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8882362864-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8882362864-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="5499184896-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5499184896-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="8882362864-42">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="8882362864-44">}</span><span class="p" data-group-id="8882362864-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-45">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-45">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-46">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="8882362864-46">}</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="5499184896-42">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="5499184896-44">}</span><span class="p" data-group-id="5499184896-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-45">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-45">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-46">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="5499184896-46">}</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% User Commands</span><span class="w">
│ │ │ │ -</span><span class="nf">logon</span><span class="p" data-group-id="8882362864-47">(</span><span class="n">Name</span><span class="p" data-group-id="8882362864-47">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8882362864-48">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8882362864-48">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">logon</span><span class="p" data-group-id="5499184896-47">(</span><span class="n">Name</span><span class="p" data-group-id="5499184896-47">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="5499184896-48">(</span><span class="ss">mess_client</span><span class="p" data-group-id="5499184896-48">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">register</span><span class="p" data-group-id="8882362864-49">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ │ -                     </span><span class="nf">spawn</span><span class="p" data-group-id="8882362864-50">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-51">[</span><span class="nf">server_node</span><span class="p" data-group-id="8882362864-52">(</span><span class="p" data-group-id="8882362864-52">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8882362864-51">]</span><span class="p" data-group-id="8882362864-50">)</span><span class="p" data-group-id="8882362864-49">)</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="nf">register</span><span class="p" data-group-id="5499184896-49">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ │ +                     </span><span class="nf">spawn</span><span class="p" data-group-id="5499184896-50">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-51">[</span><span class="nf">server_node</span><span class="p" data-group-id="5499184896-52">(</span><span class="p" data-group-id="5499184896-52">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5499184896-51">]</span><span class="p" data-group-id="5499184896-50">)</span><span class="p" data-group-id="5499184896-49">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">already_logged_on</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">logoff</span><span class="p" data-group-id="8882362864-53">(</span><span class="p" data-group-id="8882362864-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">logoff</span><span class="p" data-group-id="5499184896-53">(</span><span class="p" data-group-id="5499184896-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">logoff</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">message</span><span class="p" data-group-id="8882362864-54">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-54">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8882362864-55">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8882362864-55">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ │ +</span><span class="nf">message</span><span class="p" data-group-id="5499184896-54">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-54">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="5499184896-55">(</span><span class="ss">mess_client</span><span class="p" data-group-id="5499184896-55">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">not_logged_on</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-56">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-56">}</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-56">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-56">}</span><span class="p">,</span><span class="w">
│ │ │ │               </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% The client process which runs on each user node</span><span class="w">
│ │ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="8882362864-57">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8882362864-57">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8882362864-58">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="8882362864-58">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-59">{</span><span class="nf">self</span><span class="p" data-group-id="8882362864-60">(</span><span class="p" data-group-id="8882362864-60">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8882362864-59">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">await_result</span><span class="p" data-group-id="8882362864-61">(</span><span class="p" data-group-id="8882362864-61">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="8882362864-62">(</span><span class="n">Server_Node</span><span class="p" data-group-id="8882362864-62">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="5499184896-57">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5499184896-57">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5499184896-58">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="5499184896-58">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-59">{</span><span class="nf">self</span><span class="p" data-group-id="5499184896-60">(</span><span class="p" data-group-id="5499184896-60">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5499184896-59">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">await_result</span><span class="p" data-group-id="5499184896-61">(</span><span class="p" data-group-id="5499184896-61">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="5499184896-62">(</span><span class="n">Server_Node</span><span class="p" data-group-id="5499184896-62">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="8882362864-63">(</span><span class="n">Server_Node</span><span class="p" data-group-id="8882362864-63">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="5499184896-63">(</span><span class="n">Server_Node</span><span class="p" data-group-id="5499184896-63">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">logoff</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="8882362864-64">(</span><span class="ss">normal</span><span class="p" data-group-id="8882362864-64">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-65">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-65">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="8882362864-66">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="8882362864-66">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8882362864-67">{</span><span class="nf">self</span><span class="p" data-group-id="8882362864-68">(</span><span class="p" data-group-id="8882362864-68">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-67">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">await_result</span><span class="p" data-group-id="8882362864-69">(</span><span class="p" data-group-id="8882362864-69">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-70">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-70">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8882362864-71">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-72">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8882362864-72">]</span><span class="p" data-group-id="8882362864-71">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="5499184896-64">(</span><span class="ss">normal</span><span class="p" data-group-id="5499184896-64">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-65">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-65">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="5499184896-66">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="5499184896-66">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5499184896-67">{</span><span class="nf">self</span><span class="p" data-group-id="5499184896-68">(</span><span class="p" data-group-id="5499184896-68">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-67">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">await_result</span><span class="p" data-group-id="5499184896-69">(</span><span class="p" data-group-id="5499184896-69">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-70">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-70">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5499184896-71">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-72">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5499184896-72">]</span><span class="p" data-group-id="5499184896-71">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="8882362864-73">(</span><span class="n">Server_Node</span><span class="p" data-group-id="8882362864-73">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="5499184896-73">(</span><span class="n">Server_Node</span><span class="p" data-group-id="5499184896-73">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% wait for a response from the server</span><span class="w">
│ │ │ │ -</span><span class="nf">await_result</span><span class="p" data-group-id="8882362864-74">(</span><span class="p" data-group-id="8882362864-74">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">await_result</span><span class="p" data-group-id="5499184896-74">(</span><span class="p" data-group-id="5499184896-74">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-75">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="8882362864-75">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8882362864-76">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-77">[</span><span class="n">Why</span><span class="p" data-group-id="8882362864-77">]</span><span class="p" data-group-id="8882362864-76">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="8882362864-78">(</span><span class="ss">normal</span><span class="p" data-group-id="8882362864-78">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8882362864-79">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="8882362864-79">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8882362864-80">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-81">[</span><span class="n">What</span><span class="p" data-group-id="8882362864-81">]</span><span class="p" data-group-id="8882362864-80">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-75">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="5499184896-75">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5499184896-76">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-77">[</span><span class="n">Why</span><span class="p" data-group-id="5499184896-77">]</span><span class="p" data-group-id="5499184896-76">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="5499184896-78">(</span><span class="ss">normal</span><span class="p" data-group-id="5499184896-78">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5499184896-79">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="5499184896-79">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5499184896-80">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-81">[</span><span class="n">What</span><span class="p" data-group-id="5499184896-81">]</span><span class="p" data-group-id="5499184896-80">)</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8882362864-82">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8882362864-83">[</span><span class="p" data-group-id="8882362864-83">]</span><span class="p" data-group-id="8882362864-82">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="8882362864-84">(</span><span class="ss">timeout</span><span class="p" data-group-id="8882362864-84">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5499184896-82">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5499184896-83">[</span><span class="p" data-group-id="5499184896-83">]</span><span class="p" data-group-id="5499184896-82">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="5499184896-84">(</span><span class="ss">timeout</span><span class="p" data-group-id="5499184896-84">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The following changes are added:</p><p>The messenger server traps exits. If it receives an exit signal,
│ │ │ │  <code class="inline">{'EXIT',From,Reason}</code>, this means that a client process has terminated or is
│ │ │ │  unreachable for one of the following reasons:</p><ul><li>The user has logged off (the &quot;logoff&quot; message is removed).</li><li>The network connection to the client is broken.</li><li>The node on which the client process resides has gone down.</li><li>The client processes has done some illegal operation.</li></ul><p>If an exit signal is received as above, the tuple <code class="inline">{From,Name}</code> is deleted from
│ │ │ │  the servers <code class="inline">User_List</code> using the <code class="inline">server_logoff</code> function. If the node on which
│ │ │ │  the server runs goes down, an exit signal (automatically generated by the
│ │ │ │  system) is sent to all of the client processes:
│ │ │ │  <code class="inline">{'EXIT',MessengerPID,noconnection}</code> causing all the client processes to
│ │ │ ├── OEBPS/release_structure.xhtml
│ │ │ │ @@ -41,37 +41,37 @@
│ │ │ │    <a href="#release-resource-file" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Release Resource File</span>
│ │ │ │  </h2>
│ │ │ │  <p>To define a release, create a <em>release resource file</em>, or in short a <code class="inline">.rel</code>
│ │ │ │  file. In the file, specify the name and version of the release, which ERTS
│ │ │ │ -version it is based on, and which applications it consists of:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7046493586-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7046493586-2">{</span><span class="n">Name</span><span class="p">,</span><span class="n">Vsn</span><span class="p" data-group-id="7046493586-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7046493586-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">EVsn</span><span class="p" data-group-id="7046493586-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7046493586-4">[</span><span class="p" data-group-id="7046493586-5">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsn1</span><span class="p" data-group-id="7046493586-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +version it is based on, and which applications it consists of:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6743163607-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6743163607-2">{</span><span class="n">Name</span><span class="p">,</span><span class="n">Vsn</span><span class="p" data-group-id="6743163607-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6743163607-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">EVsn</span><span class="p" data-group-id="6743163607-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="6743163607-4">[</span><span class="p" data-group-id="6743163607-5">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsn1</span><span class="p" data-group-id="6743163607-5">}</span><span class="p">,</span><span class="w">
│ │ │ │     </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7046493586-6">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsnN</span><span class="p" data-group-id="7046493586-6">}</span><span class="p" data-group-id="7046493586-4">]</span><span class="p" data-group-id="7046493586-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Name</code>, <code class="inline">Vsn</code>, <code class="inline">EVsn</code>, and <code class="inline">AppVsn</code> are strings.</p><p>The file must be named <code class="inline">Rel.rel</code>, where <code class="inline">Rel</code> is a unique name.</p><p>Each <code class="inline">Application</code> (atom) and <code class="inline">AppVsn</code> is the name and version of an application
│ │ │ │ +  </span><span class="p" data-group-id="6743163607-6">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsnN</span><span class="p" data-group-id="6743163607-6">}</span><span class="p" data-group-id="6743163607-4">]</span><span class="p" data-group-id="6743163607-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Name</code>, <code class="inline">Vsn</code>, <code class="inline">EVsn</code>, and <code class="inline">AppVsn</code> are strings.</p><p>The file must be named <code class="inline">Rel.rel</code>, where <code class="inline">Rel</code> is a unique name.</p><p>Each <code class="inline">Application</code> (atom) and <code class="inline">AppVsn</code> is the name and version of an application
│ │ │ │  included in the release. The minimal release based on Erlang/OTP consists of the
│ │ │ │  Kernel and STDLIB applications, so these applications must be included in the
│ │ │ │  list.</p><p>If the release is to be upgraded, it must also include the SASL application.</p><p><a href="" id="ch_rel"></a></p><p>Here is an example showing the <code class="inline">.app</code> file for a release of <code class="inline">ch_app</code> from
│ │ │ │ -the <a href="applications.xhtml#ch_app">Applications</a> section:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5777115837-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="5777115837-2">[</span><span class="p" data-group-id="5777115837-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="5777115837-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5777115837-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="5777115837-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5777115837-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5777115837-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="5777115837-6">]</span><span class="p" data-group-id="5777115837-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5777115837-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5777115837-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="5777115837-8">]</span><span class="p" data-group-id="5777115837-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5777115837-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5777115837-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="5777115837-10">]</span><span class="p" data-group-id="5777115837-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5777115837-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5777115837-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="5777115837-13">[</span><span class="p" data-group-id="5777115837-13">]</span><span class="p" data-group-id="5777115837-12">}</span><span class="p" data-group-id="5777115837-11">}</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="5777115837-2">]</span><span class="p" data-group-id="5777115837-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">.rel</code> file must also contain <code class="inline">kernel</code>, <code class="inline">stdlib</code>, and <code class="inline">sasl</code>, as these
│ │ │ │ -applications are required by <code class="inline">ch_app</code>. The file is called <code class="inline">ch_rel-1.rel</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4694068205-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4694068205-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;A&quot;</span><span class="p" data-group-id="4694068205-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4694068205-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="4694068205-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4694068205-4">[</span><span class="p" data-group-id="4694068205-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="4694068205-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4694068205-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="4694068205-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4694068205-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="4694068205-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4694068205-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4694068205-8">}</span><span class="p" data-group-id="4694068205-4">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4694068205-1">}</span><span class="p">.</span></code></pre><p><a href="" id="boot"></a></p><h2 id="generating-boot-scripts" class="section-heading">
│ │ │ │ +the <a href="applications.xhtml#ch_app">Applications</a> section:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4972167574-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4972167574-2">[</span><span class="p" data-group-id="4972167574-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="4972167574-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4972167574-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4972167574-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4972167574-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4972167574-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="4972167574-6">]</span><span class="p" data-group-id="4972167574-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4972167574-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4972167574-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="4972167574-8">]</span><span class="p" data-group-id="4972167574-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4972167574-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4972167574-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="4972167574-10">]</span><span class="p" data-group-id="4972167574-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4972167574-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4972167574-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="4972167574-13">[</span><span class="p" data-group-id="4972167574-13">]</span><span class="p" data-group-id="4972167574-12">}</span><span class="p" data-group-id="4972167574-11">}</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4972167574-2">]</span><span class="p" data-group-id="4972167574-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">.rel</code> file must also contain <code class="inline">kernel</code>, <code class="inline">stdlib</code>, and <code class="inline">sasl</code>, as these
│ │ │ │ +applications are required by <code class="inline">ch_app</code>. The file is called <code class="inline">ch_rel-1.rel</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8017173706-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8017173706-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;A&quot;</span><span class="p" data-group-id="8017173706-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8017173706-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="8017173706-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8017173706-4">[</span><span class="p" data-group-id="8017173706-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="8017173706-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8017173706-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="8017173706-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8017173706-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="8017173706-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8017173706-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="8017173706-8">}</span><span class="p" data-group-id="8017173706-4">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8017173706-1">}</span><span class="p">.</span></code></pre><p><a href="" id="boot"></a></p><h2 id="generating-boot-scripts" class="section-heading">
│ │ │ │    <a href="#generating-boot-scripts" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Generating Boot Scripts</span>
│ │ │ │  </h2>
│ │ │ │  <p><a href="../../../lib/sasl/doc/html/systools.html"><code class="inline">systools</code></a> in the SASL application includes tools to build and check
│ │ │ │  releases. The functions read the <code class="inline">.rel</code> and <code class="inline">.app</code> files and perform
│ │ │ │ @@ -95,17 +95,17 @@
│ │ │ │    <a href="#creating-a-release-package" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Creating a Release Package</span>
│ │ │ │  </h2>
│ │ │ │  <p>The <a href="../../../lib/sasl/doc/html/systools.html#make_tar/2"><code class="inline">systools:make_tar/1,2</code></a> function takes a
│ │ │ │  <code class="inline">.rel</code> file as input and creates a zipped tar file with the code for
│ │ │ │ -the specified applications, a <em>release package</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="1680160096-1">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="1680160096-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +the specified applications, a <em>release package</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="3682377423-1">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="3682377423-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="1680160096-2">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="1680160096-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="3682377423-2">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="3682377423-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>The release package by default contains:</p><ul><li>The <code class="inline">.app</code> files</li><li>The <code class="inline">.rel</code> file</li><li>The object code for all applications, structured according to the
│ │ │ │  <a href="applications.xhtml#app_dir">application directory structure</a></li><li>The binary boot script renamed to <code class="inline">start.boot</code></li></ul><pre><code class="text">% tar tf ch_rel-1.tar
│ │ │ │  lib/kernel-9.2.4/ebin/kernel.app
│ │ │ │  lib/kernel-9.2.4/ebin/application.beam
│ │ │ │  ...
│ │ │ │  lib/stdlib-5.2.3/ebin/stdlib.app
│ │ │ │  lib/stdlib-5.2.3/ebin/argparse.beam
│ │ │ ├── OEBPS/release_handling.xhtml
│ │ │ │ @@ -128,38 +128,38 @@
│ │ │ │    <span class="text">update</span>
│ │ │ │  </h3>
│ │ │ │  <p>If a more complex change has been made, for example, a change to the format of
│ │ │ │  the internal state of a <a href="../../../lib/stdlib/doc/html/gen_server.html"><code class="inline">gen_server</code></a>, simple code replacement is not sufficient.
│ │ │ │  Instead, it is necessary to:</p><ul><li>Suspend the processes using the module (to avoid that they try to handle any
│ │ │ │  requests before the code replacement is completed).</li><li>Ask them to transform the internal state format and switch to the new version
│ │ │ │  of the module.</li><li>Remove the old version.</li><li>Resume the processes.</li></ul><p>This is called <em>synchronized code replacement</em> and for this the following
│ │ │ │ -instructions are used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9768921730-1">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9768921730-2">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="9768921730-2">}</span><span class="p" data-group-id="9768921730-1">}</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9768921730-3">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="9768921730-3">}</span></code></pre><p><code class="inline">update</code> with argument <code class="inline">{advanced,Extra}</code> is used when changing the internal
│ │ │ │ +instructions are used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0752332394-1">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0752332394-2">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="0752332394-2">}</span><span class="p" data-group-id="0752332394-1">}</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0752332394-3">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="0752332394-3">}</span></code></pre><p><code class="inline">update</code> with argument <code class="inline">{advanced,Extra}</code> is used when changing the internal
│ │ │ │  state of a behaviour as described above. It causes behaviour processes to call
│ │ │ │  the callback function <code class="inline">code_change/3</code>, passing the term <code class="inline">Extra</code> and some other
│ │ │ │  information as arguments. See the manual pages for the respective behaviours and
│ │ │ │  <a href="appup_cookbook.xhtml#int_state">Appup Cookbook</a>.</p><p><code class="inline">update</code> with argument <code class="inline">supervisor</code> is used when changing the start
│ │ │ │  specification of a supervisor. See <a href="appup_cookbook.xhtml#sup">Appup Cookbook</a>.</p><p>When a module is to be updated, the release handler finds which processes that
│ │ │ │  are <em>using</em> the module by traversing the supervision tree of each running
│ │ │ │ -application and checking all the child specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5937900303-1">{</span><span class="n">Id</span><span class="p">,</span><span class="w"> </span><span class="n">StartFunc</span><span class="p">,</span><span class="w"> </span><span class="n">Restart</span><span class="p">,</span><span class="w"> </span><span class="n">Shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Modules</span><span class="p" data-group-id="5937900303-1">}</span></code></pre><p>A process uses a module if the name is listed in <code class="inline">Modules</code> in the child
│ │ │ │ +application and checking all the child specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4362448569-1">{</span><span class="n">Id</span><span class="p">,</span><span class="w"> </span><span class="n">StartFunc</span><span class="p">,</span><span class="w"> </span><span class="n">Restart</span><span class="p">,</span><span class="w"> </span><span class="n">Shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Modules</span><span class="p" data-group-id="4362448569-1">}</span></code></pre><p>A process uses a module if the name is listed in <code class="inline">Modules</code> in the child
│ │ │ │  specification for the process.</p><p>If <code class="inline">Modules=dynamic</code>, which is the case for event managers, the event manager
│ │ │ │  process informs the release handler about the list of currently installed event
│ │ │ │  handlers (<code class="inline">gen_event</code>), and it is checked if the module name is in this list
│ │ │ │  instead.</p><p>The release handler suspends, asks for code change, and resumes processes by
│ │ │ │  calling the functions <code class="inline">sys:suspend/1,2</code>, <code class="inline">sys:change_code/4,5</code>, and
│ │ │ │  <code class="inline">sys:resume/1,2</code>, respectively.</p><h3 id="add_module-and-delete_module" class="section-heading">
│ │ │ │    <a href="#add_module-and-delete_module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">add_module and delete_module</span>
│ │ │ │  </h3>
│ │ │ │ -<p>If a new module is introduced, the following instruction is used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0517034090-1">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="0517034090-1">}</span></code></pre><p>This instruction loads module <code class="inline">Module</code>. When running Erlang in
│ │ │ │ +<p>If a new module is introduced, the following instruction is used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0066352939-1">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="0066352939-1">}</span></code></pre><p>This instruction loads module <code class="inline">Module</code>. When running Erlang in
│ │ │ │  embedded mode it is necessary to use this this instruction. It is not
│ │ │ │  strictly required when running Erlang in interactive mode, since the
│ │ │ │ -code server automatically searches for and loads unloaded modules.</p><p>The opposite of <code class="inline">add_module</code> is <code class="inline">delete_module</code>, which unloads a module:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8696845808-1">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="8696845808-1">}</span></code></pre><p>Any process, in any application, with <code class="inline">Module</code> as residence module, is
│ │ │ │ +code server automatically searches for and loads unloaded modules.</p><p>The opposite of <code class="inline">add_module</code> is <code class="inline">delete_module</code>, which unloads a module:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8426826546-1">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="8426826546-1">}</span></code></pre><p>Any process, in any application, with <code class="inline">Module</code> as residence module, is
│ │ │ │  killed when the instruction is evaluated. Therefore, the user must
│ │ │ │  ensure that all such processes are terminated before deleting module
│ │ │ │  <code class="inline">Module</code> to avoid a situation with failing supervisor restarts.</p><h3 id="application-instructions" class="section-heading">
│ │ │ │    <a href="#application-instructions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Application Instructions</span>
│ │ │ │ @@ -246,60 +246,60 @@
│ │ │ │  <code class="inline">.app</code> file.</li><li>Each <code class="inline">UpFromVsn</code> is a previous version of the application to upgrade from.</li><li>Each <code class="inline">DownToVsn</code> is a previous version of the application to downgrade to.</li><li>Each <code class="inline">Instructions</code> is a list of release handling instructions.</li></ul><p><code class="inline">UpFromVsn</code> and <code class="inline">DownToVsn</code> can also be specified as regular expressions. For
│ │ │ │  more information about the syntax and contents of the <code class="inline">.appup</code> file, see
│ │ │ │  <a href="../../../lib/sasl/doc/html/appup.xhtml"><code class="inline">appup</code></a> in SASL.</p><p><a href="appup_cookbook.xhtml">Appup Cookbook</a> includes examples of <code class="inline">.appup</code> files for
│ │ │ │  typical upgrade/downgrade cases.</p><p><em>Example:</em> Consider the release <code class="inline">ch_rel-1</code> from
│ │ │ │  <a href="release_structure.xhtml#ch_rel">Releases</a>. Assume you want to add a function
│ │ │ │  <code class="inline">available/0</code> to server <code class="inline">ch3</code>, which returns the number of available channels
│ │ │ │  (when trying out the example, make the change in a copy of the original
│ │ │ │ -directory, to ensure that the first version is still available):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3436520025-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="3436520025-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="3436520025-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="3436520025-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +directory, to ensure that the first version is still available):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2385360803-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="2385360803-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="2385360803-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="2385360803-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3436520025-3">(</span><span class="p" data-group-id="3436520025-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3436520025-4">]</span><span class="p" data-group-id="3436520025-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3436520025-5">(</span><span class="p" data-group-id="3436520025-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3436520025-6">]</span><span class="p" data-group-id="3436520025-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3436520025-7">(</span><span class="p" data-group-id="3436520025-8">[</span><span class="ss">available</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3436520025-8">]</span><span class="p" data-group-id="3436520025-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3436520025-9">(</span><span class="p" data-group-id="3436520025-10">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3436520025-10">]</span><span class="p" data-group-id="3436520025-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2385360803-3">(</span><span class="p" data-group-id="2385360803-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2385360803-4">]</span><span class="p" data-group-id="2385360803-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2385360803-5">(</span><span class="p" data-group-id="2385360803-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2385360803-6">]</span><span class="p" data-group-id="2385360803-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2385360803-7">(</span><span class="p" data-group-id="2385360803-8">[</span><span class="ss">available</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2385360803-8">]</span><span class="p" data-group-id="2385360803-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2385360803-9">(</span><span class="p" data-group-id="2385360803-10">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2385360803-10">]</span><span class="p" data-group-id="2385360803-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="3436520025-11">(</span><span class="p" data-group-id="3436520025-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3436520025-12">(</span><span class="p" data-group-id="3436520025-13">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3436520025-13">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3436520025-14">[</span><span class="p" data-group-id="3436520025-14">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3436520025-15">[</span><span class="p" data-group-id="3436520025-15">]</span><span class="p" data-group-id="3436520025-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="2385360803-11">(</span><span class="p" data-group-id="2385360803-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="2385360803-12">(</span><span class="p" data-group-id="2385360803-13">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="2385360803-13">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2385360803-14">[</span><span class="p" data-group-id="2385360803-14">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2385360803-15">[</span><span class="p" data-group-id="2385360803-15">]</span><span class="p" data-group-id="2385360803-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="3436520025-16">(</span><span class="p" data-group-id="3436520025-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="3436520025-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="3436520025-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="2385360803-16">(</span><span class="p" data-group-id="2385360803-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="2385360803-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="2385360803-17">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="3436520025-18">(</span><span class="n">Ch</span><span class="p" data-group-id="3436520025-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="3436520025-19">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3436520025-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3436520025-20">}</span><span class="p" data-group-id="3436520025-19">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="2385360803-18">(</span><span class="n">Ch</span><span class="p" data-group-id="2385360803-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="2385360803-19">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2385360803-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="2385360803-20">}</span><span class="p" data-group-id="2385360803-19">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">available</span><span class="p" data-group-id="3436520025-21">(</span><span class="p" data-group-id="3436520025-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="3436520025-22">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">available</span><span class="p" data-group-id="3436520025-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">available</span><span class="p" data-group-id="2385360803-21">(</span><span class="p" data-group-id="2385360803-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="2385360803-22">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">available</span><span class="p" data-group-id="2385360803-22">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3436520025-23">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="3436520025-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3436520025-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="3436520025-25">(</span><span class="p" data-group-id="3436520025-25">)</span><span class="p" data-group-id="3436520025-24">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="2385360803-23">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="2385360803-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2385360803-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="2385360803-25">(</span><span class="p" data-group-id="2385360803-25">)</span><span class="p" data-group-id="2385360803-24">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="3436520025-26">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3436520025-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3436520025-27">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3436520025-27">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="3436520025-28">(</span><span class="n">Chs</span><span class="p" data-group-id="3436520025-28">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3436520025-29">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3436520025-29">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="3436520025-30">(</span><span class="ss">available</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3436520025-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">available</span><span class="p" data-group-id="3436520025-31">(</span><span class="n">Chs</span><span class="p" data-group-id="3436520025-31">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3436520025-32">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3436520025-32">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="2385360803-26">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2385360803-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2385360803-27">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="2385360803-27">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="2385360803-28">(</span><span class="n">Chs</span><span class="p" data-group-id="2385360803-28">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2385360803-29">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="2385360803-29">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="2385360803-30">(</span><span class="ss">available</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2385360803-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">available</span><span class="p" data-group-id="2385360803-31">(</span><span class="n">Chs</span><span class="p" data-group-id="2385360803-31">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2385360803-32">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2385360803-32">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="3436520025-33">(</span><span class="p" data-group-id="3436520025-34">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3436520025-34">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3436520025-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="3436520025-35">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3436520025-35">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3436520025-36">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3436520025-36">}</span><span class="p">.</span></code></pre><p>A new version of the <code class="inline">ch_app.app</code> file must now be created, where the version is
│ │ │ │ -updated:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7437981792-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7437981792-2">[</span><span class="p" data-group-id="7437981792-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="7437981792-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7437981792-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="7437981792-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7437981792-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7437981792-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="7437981792-6">]</span><span class="p" data-group-id="7437981792-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7437981792-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7437981792-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="7437981792-8">]</span><span class="p" data-group-id="7437981792-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7437981792-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7437981792-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="7437981792-10">]</span><span class="p" data-group-id="7437981792-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7437981792-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7437981792-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="7437981792-13">[</span><span class="p" data-group-id="7437981792-13">]</span><span class="p" data-group-id="7437981792-12">}</span><span class="p" data-group-id="7437981792-11">}</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7437981792-2">]</span><span class="p" data-group-id="7437981792-1">}</span><span class="p">.</span></code></pre><p>To upgrade <code class="inline">ch_app</code> from <code class="inline">&quot;1&quot;</code> to <code class="inline">&quot;2&quot;</code> (and to downgrade from <code class="inline">&quot;2&quot;</code> to <code class="inline">&quot;1&quot;</code>),
│ │ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="2385360803-33">(</span><span class="p" data-group-id="2385360803-34">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="2385360803-34">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2385360803-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="2385360803-35">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2385360803-35">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2385360803-36">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="2385360803-36">}</span><span class="p">.</span></code></pre><p>A new version of the <code class="inline">ch_app.app</code> file must now be created, where the version is
│ │ │ │ +updated:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8036800291-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8036800291-2">[</span><span class="p" data-group-id="8036800291-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="8036800291-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8036800291-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="8036800291-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8036800291-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8036800291-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8036800291-6">]</span><span class="p" data-group-id="8036800291-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8036800291-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8036800291-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="8036800291-8">]</span><span class="p" data-group-id="8036800291-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8036800291-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8036800291-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="8036800291-10">]</span><span class="p" data-group-id="8036800291-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="8036800291-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8036800291-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="8036800291-13">[</span><span class="p" data-group-id="8036800291-13">]</span><span class="p" data-group-id="8036800291-12">}</span><span class="p" data-group-id="8036800291-11">}</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8036800291-2">]</span><span class="p" data-group-id="8036800291-1">}</span><span class="p">.</span></code></pre><p>To upgrade <code class="inline">ch_app</code> from <code class="inline">&quot;1&quot;</code> to <code class="inline">&quot;2&quot;</code> (and to downgrade from <code class="inline">&quot;2&quot;</code> to <code class="inline">&quot;1&quot;</code>),
│ │ │ │  you only need to load the new (old) version of the <code class="inline">ch3</code> callback module. Create
│ │ │ │ -the application upgrade file <code class="inline">ch_app.appup</code> in the <code class="inline">ebin</code> directory:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8451464141-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8451464141-2">[</span><span class="p" data-group-id="8451464141-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8451464141-4">[</span><span class="p" data-group-id="8451464141-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8451464141-5">}</span><span class="p" data-group-id="8451464141-4">]</span><span class="p" data-group-id="8451464141-3">}</span><span class="p" data-group-id="8451464141-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8451464141-6">[</span><span class="p" data-group-id="8451464141-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8451464141-8">[</span><span class="p" data-group-id="8451464141-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8451464141-9">}</span><span class="p" data-group-id="8451464141-8">]</span><span class="p" data-group-id="8451464141-7">}</span><span class="p" data-group-id="8451464141-6">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8451464141-1">}</span><span class="p">.</span></code></pre><p><a href="" id="relup"></a></p><h2 id="release-upgrade-file" class="section-heading">
│ │ │ │ +the application upgrade file <code class="inline">ch_app.appup</code> in the <code class="inline">ebin</code> directory:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2139992181-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2139992181-2">[</span><span class="p" data-group-id="2139992181-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2139992181-4">[</span><span class="p" data-group-id="2139992181-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="2139992181-5">}</span><span class="p" data-group-id="2139992181-4">]</span><span class="p" data-group-id="2139992181-3">}</span><span class="p" data-group-id="2139992181-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2139992181-6">[</span><span class="p" data-group-id="2139992181-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2139992181-8">[</span><span class="p" data-group-id="2139992181-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="2139992181-9">}</span><span class="p" data-group-id="2139992181-8">]</span><span class="p" data-group-id="2139992181-7">}</span><span class="p" data-group-id="2139992181-6">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2139992181-1">}</span><span class="p">.</span></code></pre><p><a href="" id="relup"></a></p><h2 id="release-upgrade-file" class="section-heading">
│ │ │ │    <a href="#release-upgrade-file" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Release Upgrade File</span>
│ │ │ │  </h2>
│ │ │ │  <p>To define how to upgrade/downgrade between the new version and previous versions
│ │ │ │  of a release, a <em>release upgrade file</em>, or in short <code class="inline">.relup</code> file, is to be
│ │ │ │ @@ -310,22 +310,22 @@
│ │ │ │  are to be added and deleted, and which applications that must be upgraded and/or
│ │ │ │  downgraded. The instructions for this are fetched from the <code class="inline">.appup</code> files and
│ │ │ │  transformed into a single list of low-level instructions in the right order.</p><p>If the <code class="inline">relup</code> file is relatively simple, it can be created manually. It is only
│ │ │ │  to contain low-level instructions.</p><p>For details about the syntax and contents of the release upgrade file, see
│ │ │ │  <a href="../../../lib/sasl/doc/html/relup.xhtml"><code class="inline">relup</code></a> in SASL.</p><p><em>Example, continued from the previous section:</em> You have a new version &quot;2&quot; of
│ │ │ │  <code class="inline">ch_app</code> and an <code class="inline">.appup</code> file. A new version of the <code class="inline">.rel</code> file is also needed.
│ │ │ │  This time the file is called <code class="inline">ch_rel-2.rel</code> and the release version string is
│ │ │ │ -changed from &quot;A&quot; to &quot;B&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2518631420-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2518631420-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="2518631420-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2518631420-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="2518631420-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2518631420-4">[</span><span class="p" data-group-id="2518631420-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="2518631420-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2518631420-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="2518631420-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2518631420-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="2518631420-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2518631420-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="2518631420-8">}</span><span class="p" data-group-id="2518631420-4">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2518631420-1">}</span><span class="p">.</span></code></pre><p>Now the <code class="inline">relup</code> file can be generated:</p><pre><code class="text">1&gt; systools:make_relup(&quot;ch_rel-2&quot;, [&quot;ch_rel-1&quot;], [&quot;ch_rel-1&quot;]).
│ │ │ │ +changed from &quot;A&quot; to &quot;B&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5270983397-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5270983397-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="5270983397-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5270983397-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="5270983397-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5270983397-4">[</span><span class="p" data-group-id="5270983397-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="5270983397-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="5270983397-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="5270983397-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="5270983397-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="5270983397-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="5270983397-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="5270983397-8">}</span><span class="p" data-group-id="5270983397-4">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5270983397-1">}</span><span class="p">.</span></code></pre><p>Now the <code class="inline">relup</code> file can be generated:</p><pre><code class="text">1&gt; systools:make_relup(&quot;ch_rel-2&quot;, [&quot;ch_rel-1&quot;], [&quot;ch_rel-1&quot;]).
│ │ │ │  ok</code></pre><p>This generates a <code class="inline">relup</code> file with instructions for how to upgrade from version
│ │ │ │  &quot;A&quot; (&quot;ch_rel-1&quot;) to version &quot;B&quot; (&quot;ch_rel-2&quot;) and how to downgrade from version
│ │ │ │  &quot;B&quot; to version &quot;A&quot;.</p><p>Both the old and new versions of the <code class="inline">.app</code> and <code class="inline">.rel</code> files must be in the code
│ │ │ │  path, as well as the <code class="inline">.appup</code> and (new) <code class="inline">.beam</code> files. The code path can be
│ │ │ │  extended by using the option <code class="inline">path</code>:</p><pre><code class="text">1&gt; systools:make_relup(&quot;ch_rel-2&quot;, [&quot;ch_rel-1&quot;], [&quot;ch_rel-1&quot;],
│ │ │ │  [{path,[&quot;../ch_rel-1&quot;,
│ │ │ │  &quot;../ch_rel-1/lib/ch_app-1/ebin&quot;]}]).
│ │ │ │ @@ -338,25 +338,25 @@
│ │ │ │  <p>When you have made a new version of a release, a release package can be created
│ │ │ │  with this new version and transferred to the target environment.</p><p>To install the new version of the release in runtime, the <em>release
│ │ │ │  handler</em> is used. This is a process belonging to the SASL application,
│ │ │ │  which handles unpacking, installation, and removal of release
│ │ │ │  packages. The <a href="../../../lib/sasl/doc/html/release_handler.html"><code class="inline">release_handler</code></a> module communicates with this process.</p><p>Assuming there is an operational target system with installation root directory
│ │ │ │  <code class="inline">$ROOT</code>, the release package with the new version of the release is to be copied
│ │ │ │  to <code class="inline">$ROOT/releases</code>.</p><p>First, <em>unpack</em> the release package. The files are then extracted from the
│ │ │ │ -package:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="3488434565-1">(</span><span class="n">ReleaseName</span><span class="p" data-group-id="3488434565-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3488434565-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p" data-group-id="3488434565-2">}</span></code></pre><ul><li><code class="inline">ReleaseName</code> is the name of the release package except the <code class="inline">.tar.gz</code>
│ │ │ │ +package:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="0340441776-1">(</span><span class="n">ReleaseName</span><span class="p" data-group-id="0340441776-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0340441776-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p" data-group-id="0340441776-2">}</span></code></pre><ul><li><code class="inline">ReleaseName</code> is the name of the release package except the <code class="inline">.tar.gz</code>
│ │ │ │  extension.</li><li><code class="inline">Vsn</code> is the version of the unpacked release, as defined in its <code class="inline">.rel</code> file.</li></ul><p>A directory <code class="inline">$ROOT/lib/releases/Vsn</code> is created, where the <code class="inline">.rel</code> file, the boot
│ │ │ │  script <code class="inline">start.boot</code>, the system configuration file <code class="inline">sys.config</code>, and <code class="inline">relup</code> are
│ │ │ │  placed. For applications with new version numbers, the application directories
│ │ │ │  are placed under <code class="inline">$ROOT/lib</code>. Unchanged applications are not affected.</p><p>An unpacked release can be <em>installed</em>. The release handler then evaluates the
│ │ │ │ -instructions in <code class="inline">relup</code>, step by step:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="1250775996-1">(</span><span class="n">Vsn</span><span class="p" data-group-id="1250775996-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1250775996-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FromVsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1250775996-3">[</span><span class="p" data-group-id="1250775996-3">]</span><span class="p" data-group-id="1250775996-2">}</span></code></pre><p>If an error occurs during the installation, the system is rebooted using the old
│ │ │ │ +instructions in <code class="inline">relup</code>, step by step:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="0525701477-1">(</span><span class="n">Vsn</span><span class="p" data-group-id="0525701477-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0525701477-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FromVsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0525701477-3">[</span><span class="p" data-group-id="0525701477-3">]</span><span class="p" data-group-id="0525701477-2">}</span></code></pre><p>If an error occurs during the installation, the system is rebooted using the old
│ │ │ │  version of the release. If installation succeeds, the system is afterwards using
│ │ │ │  the new version of the release, but if anything happens and the system is
│ │ │ │  rebooted, it starts using the previous version again.</p><p>To be made the default version, the newly installed release must be made
│ │ │ │  <em>permanent</em>, which means the previous version becomes <em>old</em>:</p><pre><code class="text">release_handler:make_permanent(Vsn) =&gt; ok</code></pre><p>The system keeps information about which versions are old and permanent in the
│ │ │ │ -files <code class="inline">$ROOT/releases/RELEASES</code> and <code class="inline">$ROOT/releases/start_erl.data</code>.</p><p>To downgrade from <code class="inline">Vsn</code> to <code class="inline">FromVsn</code>, <code class="inline">install_release</code> must be called again:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="1445021282-1">(</span><span class="n">FromVsn</span><span class="p" data-group-id="1445021282-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1445021282-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1445021282-3">[</span><span class="p" data-group-id="1445021282-3">]</span><span class="p" data-group-id="1445021282-2">}</span></code></pre><p>An installed, but not permanent, release can be <em>removed</em>. Information about the
│ │ │ │ +files <code class="inline">$ROOT/releases/RELEASES</code> and <code class="inline">$ROOT/releases/start_erl.data</code>.</p><p>To downgrade from <code class="inline">Vsn</code> to <code class="inline">FromVsn</code>, <code class="inline">install_release</code> must be called again:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="4253372650-1">(</span><span class="n">FromVsn</span><span class="p" data-group-id="4253372650-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4253372650-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4253372650-3">[</span><span class="p" data-group-id="4253372650-3">]</span><span class="p" data-group-id="4253372650-2">}</span></code></pre><p>An installed, but not permanent, release can be <em>removed</em>. Information about the
│ │ │ │  release is then deleted from <code class="inline">$ROOT/releases/RELEASES</code> and the release-specific
│ │ │ │  code, that is, the new application directories and the <code class="inline">$ROOT/releases/Vsn</code>
│ │ │ │  directory, are removed.</p><pre><code class="text">release_handler:remove_release(Vsn) =&gt; ok</code></pre><h3 id="example-continued-from-the-previous-sections" class="section-heading">
│ │ │ │    <a href="#example-continued-from-the-previous-sections" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Example (continued from the previous sections)</span>
│ │ │ │ @@ -367,17 +367,17 @@
│ │ │ │  is needed, the file is to contain the empty list:</p><pre><code class="text">[].</code></pre><p><em>Step 2)</em> Start the system as a simple target system. In reality, it is to be
│ │ │ │  started as an embedded system. However, using <code class="inline">erl</code> with the correct boot script
│ │ │ │  and config file is enough for illustration purposes:</p><pre><code class="text">% cd $ROOT
│ │ │ │  % bin/erl -boot $ROOT/releases/A/start -config $ROOT/releases/A/sys
│ │ │ │  ...</code></pre><p><code class="inline">$ROOT</code> is the installation directory of the target system.</p><p><em>Step 3)</em> In another Erlang shell, generate start scripts and create a release
│ │ │ │  package for the new version <code class="inline">&quot;B&quot;</code>. Remember to include (a possible updated)
│ │ │ │  <code class="inline">sys.config</code> and the <code class="inline">relup</code> file. For more information, see
│ │ │ │ -<a href="release_handling.xhtml#relup">Release Upgrade File</a>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="7958590576-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="7958590576-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<a href="release_handling.xhtml#relup">Release Upgrade File</a>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="1219817242-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="1219817242-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="7958590576-2">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="7958590576-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="1219817242-2">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="1219817242-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>The new release package now also contains version &quot;2&quot; of <code class="inline">ch_app</code> and the
│ │ │ │  <code class="inline">relup</code> file:</p><pre><code class="text">% tar tf ch_rel-2.tar
│ │ │ │  lib/kernel-9.2.4/ebin/kernel.app
│ │ │ │  lib/kernel-9.2.4/ebin/application.beam
│ │ │ │  ...
│ │ │ │  lib/stdlib-5.2.3/ebin/stdlib.app
│ │ │ │  lib/stdlib-5.2.3/ebin/argparse.beam
│ │ │ │ @@ -390,31 +390,31 @@
│ │ │ │  lib/ch_app-2/ebin/ch_sup.beam
│ │ │ │  lib/ch_app-2/ebin/ch3.beam
│ │ │ │  releases/B/start.boot
│ │ │ │  releases/B/relup
│ │ │ │  releases/B/sys.config
│ │ │ │  releases/B/ch_rel-2.rel
│ │ │ │  releases/ch_rel-2.rel</code></pre><p><em>Step 4)</em> Copy the release package <code class="inline">ch_rel-2.tar.gz</code> to the <code class="inline">$ROOT/releases</code>
│ │ │ │ -directory.</p><p><em>Step 5)</em> In the running target system, unpack the release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="3835935367-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="3835935367-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3835935367-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="3835935367-2">}</span></code></pre><p>The new application version <code class="inline">ch_app-2</code> is installed under <code class="inline">$ROOT/lib</code> next to
│ │ │ │ +directory.</p><p><em>Step 5)</em> In the running target system, unpack the release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="8533402559-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="8533402559-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8533402559-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="8533402559-2">}</span></code></pre><p>The new application version <code class="inline">ch_app-2</code> is installed under <code class="inline">$ROOT/lib</code> next to
│ │ │ │  <code class="inline">ch_app-1</code>. The <code class="inline">kernel</code>, <code class="inline">stdlib</code>, and <code class="inline">sasl</code> directories are not affected, as
│ │ │ │  they have not changed.</p><p>Under <code class="inline">$ROOT/releases</code>, a new directory <code class="inline">B</code> is created, containing
│ │ │ │ -<code class="inline">ch_rel-2.rel</code>, <code class="inline">start.boot</code>, <code class="inline">sys.config</code>, and <code class="inline">relup</code>.</p><p><em>Step 6)</em> Check if the function <code class="inline">ch3:available/0</code> is available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="7578120417-1">(</span><span class="p" data-group-id="7578120417-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">ch_rel-2.rel</code>, <code class="inline">start.boot</code>, <code class="inline">sys.config</code>, and <code class="inline">relup</code>.</p><p><em>Step 6)</em> Check if the function <code class="inline">ch3:available/0</code> is available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="3588003943-1">(</span><span class="p" data-group-id="3588003943-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: undefined function ch3:available/0</span></code></pre><p><em>Step 7)</em> Install the new release. The instructions in <code class="inline">$ROOT/releases/B/relup</code>
│ │ │ │  are executed one by one, resulting in the new version of <code class="inline">ch3</code> being loaded. The
│ │ │ │ -function <code class="inline">ch3:available/0</code> is now available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="3792941888-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="3792941888-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3792941888-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="p" data-group-id="3792941888-3">[</span><span class="p" data-group-id="3792941888-3">]</span><span class="p" data-group-id="3792941888-2">}</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="3792941888-4">(</span><span class="p" data-group-id="3792941888-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +function <code class="inline">ch3:available/0</code> is now available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="5768092591-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="5768092591-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5768092591-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="p" data-group-id="5768092591-3">[</span><span class="p" data-group-id="5768092591-3">]</span><span class="p" data-group-id="5768092591-2">}</span><span class="gp unselectable">
│ │ │ │ +4&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="5768092591-4">(</span><span class="p" data-group-id="5768092591-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="3792941888-5">(</span><span class="ss">ch3</span><span class="p" data-group-id="3792941888-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="5768092591-5">(</span><span class="ss">ch3</span><span class="p" data-group-id="5768092591-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;.../lib/ch_app-2/ebin/ch3.beam&quot;</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="3792941888-6">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="3792941888-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="5768092591-6">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="5768092591-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;.../lib/ch_app-1/ebin/ch_sup.beam&quot;</span></code></pre><p>Processes in <code class="inline">ch_app</code> for which code have not been updated, for example, the
│ │ │ │  supervisor, are still evaluating code from <code class="inline">ch_app-1</code>.</p><p><em>Step 8)</em> If the target system is now rebooted, it uses version &quot;A&quot; again. The
│ │ │ │ -&quot;B&quot; version must be made permanent, to be used when the system is rebooted.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">make_permanent</span><span class="p" data-group-id="3844498124-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="3844498124-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&quot;B&quot; version must be made permanent, to be used when the system is rebooted.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">make_permanent</span><span class="p" data-group-id="4928019740-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="4928019740-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p><a href="" id="sys"></a></p><h2 id="updating-application-specifications" class="section-heading">
│ │ │ │    <a href="#updating-application-specifications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Updating Application Specifications</span>
│ │ │ │  </h2>
│ │ │ │  <p>When a new version of a release is installed, the application specifications are
│ │ │ │ @@ -423,14 +423,14 @@
│ │ │ │  boot script is generated from the same <code class="inline">.rel</code> file as is used to build the
│ │ │ │  release package itself.</p></section><p>Specifically, the application configuration parameters are automatically updated
│ │ │ │  according to (in increasing priority order):</p><ul><li>The data in the boot script, fetched from the new application resource file
│ │ │ │  <code class="inline">App.app</code></li><li>The new <code class="inline">sys.config</code></li><li>Command-line arguments <code class="inline">-App Par Val</code></li></ul><p>This means that parameter values set in the other system configuration files and
│ │ │ │  values set using <a href="../../../lib/kernel/doc/html/application.html#set_env/3"><code class="inline">application:set_env/3</code></a> are disregarded.</p><p>When an installed release is made permanent, the system process <code class="inline">init</code> is set to
│ │ │ │  point out the new <code class="inline">sys.config</code>.</p><p>After the installation, the application controller compares the old and new
│ │ │ │  configuration parameters for all running applications and call the callback
│ │ │ │ -function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">config_change</span><span class="p" data-group-id="2793637910-1">(</span><span class="n">Changed</span><span class="p">,</span><span class="w"> </span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">Removed</span><span class="p" data-group-id="2793637910-1">)</span></code></pre><ul><li><code class="inline">Module</code> is the application callback module as defined by the <code class="inline">mod</code> key in the
│ │ │ │ +function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">config_change</span><span class="p" data-group-id="9094374630-1">(</span><span class="n">Changed</span><span class="p">,</span><span class="w"> </span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">Removed</span><span class="p" data-group-id="9094374630-1">)</span></code></pre><ul><li><code class="inline">Module</code> is the application callback module as defined by the <code class="inline">mod</code> key in the
│ │ │ │  <code class="inline">.app</code> file.</li><li><code class="inline">Changed</code> and <code class="inline">New</code> are lists of <code class="inline">{Par,Val}</code> for all changed and added
│ │ │ │  configuration parameters, respectively.</li><li><code class="inline">Removed</code> is a list of all parameters <code class="inline">Par</code> that have been removed.</li></ul><p>The function is optional and can be omitted when implementing an application
│ │ │ │  callback module.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/ref_man_records.xhtml
│ │ │ │ @@ -28,17 +28,17 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Defining Records</span>
│ │ │ │  </h2>
│ │ │ │  <p>A record definition consists of the name of the record, followed by the field
│ │ │ │  names of the record. Record and field names must be atoms. Each field can be
│ │ │ │  given an optional default value. If no default value is supplied, <code class="inline">undefined</code> is
│ │ │ │ -used.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2059399935-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2059399935-2">{</span><span class="n">Field1</span><span class="w"> </span><span class="p" data-group-id="2059399935-3">[</span><span class="o">=</span><span class="w"> </span><span class="n">Expr1</span><span class="p" data-group-id="2059399935-3">]</span><span class="p">,</span><span class="w">
│ │ │ │ +used.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3780431250-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3780431250-2">{</span><span class="n">Field1</span><span class="w"> </span><span class="p" data-group-id="3780431250-3">[</span><span class="o">=</span><span class="w"> </span><span class="n">Expr1</span><span class="p" data-group-id="3780431250-3">]</span><span class="p">,</span><span class="w">
│ │ │ │                 </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -               </span><span class="n">FieldN</span><span class="w"> </span><span class="p" data-group-id="2059399935-4">[</span><span class="o">=</span><span class="w"> </span><span class="n">ExprN</span><span class="p" data-group-id="2059399935-4">]</span><span class="p" data-group-id="2059399935-2">}</span><span class="p" data-group-id="2059399935-1">)</span><span class="p">.</span></code></pre><p>The default value for a field is an arbitrary expression, except that it must
│ │ │ │ +               </span><span class="n">FieldN</span><span class="w"> </span><span class="p" data-group-id="3780431250-4">[</span><span class="o">=</span><span class="w"> </span><span class="n">ExprN</span><span class="p" data-group-id="3780431250-4">]</span><span class="p" data-group-id="3780431250-2">}</span><span class="p" data-group-id="3780431250-1">)</span><span class="p">.</span></code></pre><p>The default value for a field is an arbitrary expression, except that it must
│ │ │ │  not use any variables.</p><p>A record definition can be placed anywhere among the attributes and function
│ │ │ │  declarations of a module, but the definition must come before any usage of the
│ │ │ │  record.</p><p>If a record is used in several modules, it is recommended that the record
│ │ │ │  definition is placed in an include file.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Starting from Erlang/OTP 26, records can be defined in the Erlang shell
│ │ │ │  using the syntax described in this section. In earlier releases, it was
│ │ │ │  necessary to use the <a href="../../../lib/stdlib/doc/html/shell.html"><code class="inline">shell</code></a> built-in function <code class="inline">rd/2</code>.</p></section><h2 id="creating-records" class="section-heading">
│ │ │ │    <a href="#creating-records" class="hover-link">
│ │ │ │ @@ -48,32 +48,32 @@
│ │ │ │  </h2>
│ │ │ │  <p>The following expression creates a new <code class="inline">Name</code> record where the value of each
│ │ │ │  field <code class="inline">FieldI</code> is the value of evaluating the corresponding expression <code class="inline">ExprI</code>:</p><pre><code class="text">#Name{Field1=Expr1, ..., FieldK=ExprK}</code></pre><p>The fields can be in any order, not necessarily the same order as in the record
│ │ │ │  definition, and fields can be omitted. Omitted fields get their respective
│ │ │ │  default value instead.</p><p>If several fields are to be assigned the same value, the following construction
│ │ │ │  can be used:</p><pre><code class="text">#Name{Field1=Expr1, ..., FieldK=ExprK, _=ExprL}</code></pre><p>Omitted fields then get the value of evaluating <code class="inline">ExprL</code> instead of their default
│ │ │ │  values. This feature is primarily intended to be used to create patterns for ETS
│ │ │ │ -and Mnesia match functions.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2151367858-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2151367858-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="2151367858-2">}</span><span class="p" data-group-id="2151367858-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +and Mnesia match functions.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5837109080-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5837109080-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="5837109080-2">}</span><span class="p" data-group-id="5837109080-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">lookup</span><span class="p" data-group-id="2151367858-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="2151367858-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="2151367858-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2151367858-5">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="2151367858-5">}</span><span class="p" data-group-id="2151367858-4">)</span><span class="p">.</span></code></pre><h2 id="accessing-record-fields" class="section-heading">
│ │ │ │ +</span><span class="nf">lookup</span><span class="p" data-group-id="5837109080-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="5837109080-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="5837109080-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5837109080-5">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="5837109080-5">}</span><span class="p" data-group-id="5837109080-4">)</span><span class="p">.</span></code></pre><h2 id="accessing-record-fields" class="section-heading">
│ │ │ │    <a href="#accessing-record-fields" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Accessing Record Fields</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="text">Expr#Name.Field</code></pre><p>Returns the value of the specified field. <code class="inline">Expr</code> is to evaluate to a <code class="inline">Name</code>
│ │ │ │ -record.</p><p><em>Example</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3906082569-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3906082569-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="3906082569-2">}</span><span class="p" data-group-id="3906082569-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +record.</p><p><em>Example</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7724010768-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7724010768-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="7724010768-2">}</span><span class="p" data-group-id="7724010768-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">get_person_name</span><span class="p" data-group-id="3906082569-3">(</span><span class="n">Person</span><span class="p" data-group-id="3906082569-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">get_person_name</span><span class="p" data-group-id="7724010768-3">(</span><span class="n">Person</span><span class="p" data-group-id="7724010768-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">.</span></code></pre><p>The following expression returns the position of the specified field in the
│ │ │ │ -tuple representation of the record:</p><pre><code class="text">#Name.Field</code></pre><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2375039631-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2375039631-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="2375039631-2">}</span><span class="p" data-group-id="2375039631-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +tuple representation of the record:</p><pre><code class="text">#Name.Field</code></pre><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="0665307415-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0665307415-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="0665307415-2">}</span><span class="p" data-group-id="0665307415-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">lookup</span><span class="p" data-group-id="2375039631-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2375039631-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="2375039631-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2375039631-4">)</span><span class="p">.</span></code></pre><h2 id="updating-records" class="section-heading">
│ │ │ │ +</span><span class="nf">lookup</span><span class="p" data-group-id="0665307415-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="0665307415-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="0665307415-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="0665307415-4">)</span><span class="p">.</span></code></pre><h2 id="updating-records" class="section-heading">
│ │ │ │    <a href="#updating-records" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Updating Records</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="text">Expr#Name{Field1=Expr1, ..., FieldK=ExprK}</code></pre><p><code class="inline">Expr</code> is to evaluate to a <code class="inline">Name</code> record. A copy of this record is returned,
│ │ │ │  with the value of each specified field <code class="inline">FieldI</code> changed to the value of
│ │ │ │ @@ -83,48 +83,48 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Records in Guards</span>
│ │ │ │  </h2>
│ │ │ │  <p>Since record expressions are expanded to tuple expressions, creating
│ │ │ │  records and accessing record fields are allowed in guards. However,
│ │ │ │  all subexpressions (for initializing fields), must be valid guard
│ │ │ │ -expressions as well.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="7997810756-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7997810756-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Msg</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">#</span><span class="ss">msg</span><span class="p" data-group-id="7997810756-2">{</span><span class="ss">to</span><span class="o">=</span><span class="ss">void</span><span class="p">,</span><span class="w"> </span><span class="ss">no</span><span class="o">=</span><span class="mi">3</span><span class="p" data-group-id="7997810756-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +expressions as well.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="2270443237-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="2270443237-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Msg</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">#</span><span class="ss">msg</span><span class="p" data-group-id="2270443237-2">{</span><span class="ss">to</span><span class="o">=</span><span class="ss">void</span><span class="p">,</span><span class="w"> </span><span class="ss">no</span><span class="o">=</span><span class="mi">3</span><span class="p" data-group-id="2270443237-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle</span><span class="p" data-group-id="7997810756-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7997810756-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">running</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>There is also a type test BIF <a href="../../../lib/../erts/doc/html/erlang.html#is_record/2"><code class="inline">is_record(Term, RecordTag)</code></a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_person</span><span class="p" data-group-id="2670192306-1">(</span><span class="n">P</span><span class="p" data-group-id="2670192306-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="2670192306-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="2670192306-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle</span><span class="p" data-group-id="2270443237-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="2270443237-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">running</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>There is also a type test BIF <a href="../../../lib/../erts/doc/html/erlang.html#is_record/2"><code class="inline">is_record(Term, RecordTag)</code></a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_person</span><span class="p" data-group-id="6227152888-1">(</span><span class="n">P</span><span class="p" data-group-id="6227152888-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="6227152888-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="6227152888-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">is_person</span><span class="p" data-group-id="2670192306-3">(</span><span class="p">_</span><span class="n">P</span><span class="p" data-group-id="2670192306-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">is_person</span><span class="p" data-group-id="6227152888-3">(</span><span class="p">_</span><span class="n">P</span><span class="p" data-group-id="6227152888-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">false</span><span class="p">.</span></code></pre><h2 id="records-in-patterns" class="section-heading">
│ │ │ │    <a href="#records-in-patterns" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Records in Patterns</span>
│ │ │ │  </h2>
│ │ │ │  <p>A pattern that matches a certain record is created in the same way as a record
│ │ │ │  is created:</p><pre><code class="text">#Name{Field1=Expr1, ..., FieldK=ExprK}</code></pre><p>In this case, one or more of <code class="inline">Expr1</code> ... <code class="inline">ExprK</code> can be unbound variables.</p><h2 id="nested-records" class="section-heading">
│ │ │ │    <a href="#nested-records" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Nested Records</span>
│ │ │ │  </h2>
│ │ │ │ -<p>Assume the following record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6078151762-1">(</span><span class="ss">nrec0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6078151762-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested0&quot;</span><span class="p" data-group-id="6078151762-2">}</span><span class="p" data-group-id="6078151762-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6078151762-3">(</span><span class="ss">nrec1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6078151762-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec0</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec0</span><span class="p" data-group-id="6078151762-5">{</span><span class="p" data-group-id="6078151762-5">}</span><span class="p" data-group-id="6078151762-4">}</span><span class="p" data-group-id="6078151762-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6078151762-6">(</span><span class="ss">nrec2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6078151762-7">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested2&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec1</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec1</span><span class="p" data-group-id="6078151762-8">{</span><span class="p" data-group-id="6078151762-8">}</span><span class="p" data-group-id="6078151762-7">}</span><span class="p" data-group-id="6078151762-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>Assume the following record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4563910138-1">(</span><span class="ss">nrec0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4563910138-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested0&quot;</span><span class="p" data-group-id="4563910138-2">}</span><span class="p" data-group-id="4563910138-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4563910138-3">(</span><span class="ss">nrec1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4563910138-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec0</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec0</span><span class="p" data-group-id="4563910138-5">{</span><span class="p" data-group-id="4563910138-5">}</span><span class="p" data-group-id="4563910138-4">}</span><span class="p" data-group-id="4563910138-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4563910138-6">(</span><span class="ss">nrec2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4563910138-7">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested2&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec1</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec1</span><span class="p" data-group-id="4563910138-8">{</span><span class="p" data-group-id="4563910138-8">}</span><span class="p" data-group-id="4563910138-7">}</span><span class="p" data-group-id="4563910138-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">N2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">nrec2</span><span class="p" data-group-id="6078151762-9">{</span><span class="p" data-group-id="6078151762-9">}</span><span class="p">,</span></code></pre><p>Accessing or updating nested records can be written without parentheses:</p><pre><code class="text">&quot;nested0&quot; = N2#nrec2.nrec1#nrec1.nrec0#nrec0.name,
│ │ │ │ +</span><span class="n">N2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">nrec2</span><span class="p" data-group-id="4563910138-9">{</span><span class="p" data-group-id="4563910138-9">}</span><span class="p">,</span></code></pre><p>Accessing or updating nested records can be written without parentheses:</p><pre><code class="text">&quot;nested0&quot; = N2#nrec2.nrec1#nrec1.nrec0#nrec0.name,
│ │ │ │      N0n = N2#nrec2.nrec1#nrec1.nrec0#nrec0{name = &quot;nested0a&quot;},</code></pre><p>which is equivalent to:</p><pre><code class="text">&quot;nested0&quot; = ((N2#nrec2.nrec1)#nrec1.nrec0)#nrec0.name,
│ │ │ │  N0n = ((N2#nrec2.nrec1)#nrec1.nrec0)#nrec0{name = &quot;nested0a&quot;},</code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP R14, parentheses were necessary when accessing or updating
│ │ │ │  nested records.</p></section><h2 id="internal-representation-of-records" class="section-heading">
│ │ │ │    <a href="#internal-representation-of-records" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Internal Representation of Records</span>
│ │ │ │  </h2>
│ │ │ │  <p>Record expressions are translated to tuple expressions during compilation. A
│ │ │ │ -record defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8153366062-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8153366062-2">{</span><span class="n">Field1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">FieldN</span><span class="p" data-group-id="8153366062-2">}</span><span class="p" data-group-id="8153366062-1">)</span><span class="p">.</span></code></pre><p>is internally represented by the tuple:</p><pre><code class="text">{Name, Value1, ..., ValueN}</code></pre><p>Here each <code class="inline">ValueI</code> is the default value for <code class="inline">FieldI</code>.</p><p>To each module using records, a pseudo function is added during compilation to
│ │ │ │ -obtain information about records:</p><pre><code class="makeup erlang" translate="no"><span class="nf">record_info</span><span class="p" data-group-id="5518850507-1">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="5518850507-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5518850507-2">[</span><span class="n">Field</span><span class="p" data-group-id="5518850507-2">]</span><span class="w">
│ │ │ │ -</span><span class="nf">record_info</span><span class="p" data-group-id="5518850507-3">(</span><span class="nb">size</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="5518850507-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Size</span></code></pre><p><code class="inline">Size</code> is the size of the tuple representation, that is, one more than the
│ │ │ │ +record defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1820776088-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1820776088-2">{</span><span class="n">Field1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">FieldN</span><span class="p" data-group-id="1820776088-2">}</span><span class="p" data-group-id="1820776088-1">)</span><span class="p">.</span></code></pre><p>is internally represented by the tuple:</p><pre><code class="text">{Name, Value1, ..., ValueN}</code></pre><p>Here each <code class="inline">ValueI</code> is the default value for <code class="inline">FieldI</code>.</p><p>To each module using records, a pseudo function is added during compilation to
│ │ │ │ +obtain information about records:</p><pre><code class="makeup erlang" translate="no"><span class="nf">record_info</span><span class="p" data-group-id="1373301987-1">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="1373301987-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1373301987-2">[</span><span class="n">Field</span><span class="p" data-group-id="1373301987-2">]</span><span class="w">
│ │ │ │ +</span><span class="nf">record_info</span><span class="p" data-group-id="1373301987-3">(</span><span class="nb">size</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="1373301987-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Size</span></code></pre><p><code class="inline">Size</code> is the size of the tuple representation, that is, one more than the
│ │ │ │  number of fields.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/ref_man_processes.xhtml
│ │ │ │ @@ -30,18 +30,18 @@
│ │ │ │  (grow and shrink dynamically) with small memory footprint, fast to create and
│ │ │ │  terminate, and the scheduling overhead is low.</p><h2 id="process-creation" class="section-heading">
│ │ │ │    <a href="#process-creation" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Process Creation</span>
│ │ │ │  </h2>
│ │ │ │ -<p>A process is created by calling <a href="../../../lib/../erts/doc/html/erlang.html#spawn/3"><code class="inline">spawn()</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="0156586727-1">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="0156586727-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pid</span><span class="p" data-group-id="0156586727-2">(</span><span class="p" data-group-id="0156586727-2">)</span><span class="w">
│ │ │ │ -  </span><span class="n">Module</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="0156586727-3">(</span><span class="p" data-group-id="0156586727-3">)</span><span class="w">
│ │ │ │ -  </span><span class="n">Args</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0156586727-4">[</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="0156586727-4">]</span><span class="w">
│ │ │ │ -    </span><span class="n">ArgI</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0156586727-5">(</span><span class="p" data-group-id="0156586727-5">)</span></code></pre><p><code class="inline">spawn()</code> creates a new process and returns the pid.</p><p>The new process starts executing in <code class="inline">Module:Name(Arg1,...,ArgN)</code> where the
│ │ │ │ +<p>A process is created by calling <a href="../../../lib/../erts/doc/html/erlang.html#spawn/3"><code class="inline">spawn()</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="9251304732-1">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="9251304732-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pid</span><span class="p" data-group-id="9251304732-2">(</span><span class="p" data-group-id="9251304732-2">)</span><span class="w">
│ │ │ │ +  </span><span class="n">Module</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="9251304732-3">(</span><span class="p" data-group-id="9251304732-3">)</span><span class="w">
│ │ │ │ +  </span><span class="n">Args</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9251304732-4">[</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="9251304732-4">]</span><span class="w">
│ │ │ │ +    </span><span class="n">ArgI</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="9251304732-5">(</span><span class="p" data-group-id="9251304732-5">)</span></code></pre><p><code class="inline">spawn()</code> creates a new process and returns the pid.</p><p>The new process starts executing in <code class="inline">Module:Name(Arg1,...,ArgN)</code> where the
│ │ │ │  arguments are the elements of the (possible empty) <code class="inline">Args</code> argument list.</p><p>There exist a number of different <code class="inline">spawn</code> BIFs:</p><ul><li><a href="../../../lib/../erts/doc/html/erlang.html#spawn/4"><code class="inline">spawn/1,2,3,4</code></a></li><li><a href="../../../lib/../erts/doc/html/erlang.html#spawn_link/4"><code class="inline">spawn_link/1,2,3,4</code></a></li><li><a href="../../../lib/../erts/doc/html/erlang.html#spawn_monitor/4"><code class="inline">spawn_monitor/1,2,3,4</code></a></li><li><a href="../../../lib/../erts/doc/html/erlang.html#spawn_opt/5"><code class="inline">spawn_opt/2,3,4,5</code></a></li><li><a href="../../../lib/../erts/doc/html/erlang.html#spawn_request/5"><code class="inline">spawn_request/1,2,3,4,5</code></a></li></ul><h2 id="registered-processes" class="section-heading">
│ │ │ │    <a href="#registered-processes" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Registered Processes</span>
│ │ │ │  </h2>
│ │ │ │  <p>Besides addressing a process by using its pid, there are also BIFs for
│ │ │ ├── OEBPS/ref_man_functions.xhtml
│ │ │ │ @@ -25,51 +25,51 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Function Declaration Syntax</span>
│ │ │ │  </h2>
│ │ │ │  <p>A <em>function declaration</em> is a sequence of function clauses separated by
│ │ │ │  semicolons, and terminated by a period (<code class="inline">.</code>).</p><p>A <em>function clause</em> consists of a <em>clause head</em> and a <em>clause body</em>, separated by
│ │ │ │  <code class="inline">-&gt;</code>.</p><p>A clause <em>head</em> consists of the function name, an argument list, and an optional
│ │ │ │ -guard sequence beginning with the keyword <code class="inline">when</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="p" data-group-id="4542031522-1">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="4542031522-1">)</span><span class="w"> </span><span class="p" data-group-id="4542031522-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="4542031522-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +guard sequence beginning with the keyword <code class="inline">when</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="p" data-group-id="8028829445-1">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="8028829445-1">)</span><span class="w"> </span><span class="p" data-group-id="8028829445-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="8028829445-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="n">Name</span><span class="p" data-group-id="4542031522-3">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="4542031522-3">)</span><span class="w"> </span><span class="p" data-group-id="4542031522-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="4542031522-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="n">Name</span><span class="p" data-group-id="8028829445-3">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="8028829445-3">)</span><span class="w"> </span><span class="p" data-group-id="8028829445-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="8028829445-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">BodyK</span><span class="p">.</span></code></pre><p>The function name is an atom. Each argument is a pattern.</p><p>The number of arguments <code class="inline">N</code> is the <em>arity</em> of the function. A function is
│ │ │ │  uniquely defined by the module name, function name, and arity. That is, two
│ │ │ │  functions with the same name and in the same module, but with different arities
│ │ │ │  are two different functions.</p><p>A function named <code class="inline">f</code> in module <code class="inline">mod</code> and with arity <code class="inline">N</code> is often denoted as
│ │ │ │  <code class="inline">mod:f/N</code>.</p><p>A clause <em>body</em> consists of a sequence of expressions separated by comma (<code class="inline">,</code>):</p><pre><code class="text">Expr1,
│ │ │ │  ...,
│ │ │ │  ExprN</code></pre><p>Valid Erlang expressions and guard sequences are described in
│ │ │ │ -<a href="expressions.xhtml">Expressions</a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">fact</span><span class="p" data-group-id="0206203345-1">(</span><span class="n">N</span><span class="p" data-group-id="0206203345-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% first clause head</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="0206203345-2">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="0206203345-2">)</span><span class="p">;</span><span class="w">     </span><span class="c1">% first clause body</span><span class="w">
│ │ │ │ +<a href="expressions.xhtml">Expressions</a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">fact</span><span class="p" data-group-id="8348550094-1">(</span><span class="n">N</span><span class="p" data-group-id="8348550094-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% first clause head</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="8348550094-2">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="8348550094-2">)</span><span class="p">;</span><span class="w">     </span><span class="c1">% first clause body</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="0206203345-3">(</span><span class="mi">0</span><span class="p" data-group-id="0206203345-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">             </span><span class="c1">% second clause head</span><span class="w">
│ │ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="8348550094-3">(</span><span class="mi">0</span><span class="p" data-group-id="8348550094-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">             </span><span class="c1">% second clause head</span><span class="w">
│ │ │ │      </span><span class="mi">1</span><span class="p">.</span><span class="w">                 </span><span class="c1">% second clause body</span></code></pre><p><a href="" id="eval"></a></p><h2 id="function-evaluation" class="section-heading">
│ │ │ │    <a href="#function-evaluation" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Function Evaluation</span>
│ │ │ │  </h2>
│ │ │ │  <p>When a function <code class="inline">M:F/N</code> is called, first the code for the function is located.
│ │ │ │  If the function cannot be found, an <code class="inline">undef</code> runtime error occurs. Notice that
│ │ │ │  the function must be exported to be visible outside the module it is defined in.</p><p>If the function is found, the function clauses are scanned sequentially until a
│ │ │ │  clause is found that fulfills both of the following two conditions:</p><ol><li>The patterns in the clause head can be successfully matched against the given
│ │ │ │  arguments.</li><li>The guard sequence, if any, is true.</li></ol><p>If such a clause cannot be found, a <code class="inline">function_clause</code> runtime error occurs.</p><p>If such a clause is found, the corresponding clause body is evaluated. That is,
│ │ │ │  the expressions in the body are evaluated sequentially and the value of the last
│ │ │ │ -expression is returned.</p><p>Consider the function <code class="inline">fact</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6366895536-1">(</span><span class="ss">mod</span><span class="p" data-group-id="6366895536-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6366895536-2">(</span><span class="p" data-group-id="6366895536-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6366895536-3">]</span><span class="p" data-group-id="6366895536-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +expression is returned.</p><p>Consider the function <code class="inline">fact</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4841069129-1">(</span><span class="ss">mod</span><span class="p" data-group-id="4841069129-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4841069129-2">(</span><span class="p" data-group-id="4841069129-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4841069129-3">]</span><span class="p" data-group-id="4841069129-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="6366895536-4">(</span><span class="n">N</span><span class="p" data-group-id="6366895536-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="6366895536-5">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="6366895536-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="6366895536-6">(</span><span class="mi">0</span><span class="p" data-group-id="6366895536-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="4841069129-4">(</span><span class="n">N</span><span class="p" data-group-id="4841069129-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="4841069129-5">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4841069129-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="4841069129-6">(</span><span class="mi">0</span><span class="p" data-group-id="4841069129-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="mi">1</span><span class="p">.</span></code></pre><p>Assume that you want to calculate the factorial for 1:</p><pre><code class="text">1&gt; mod:fact(1).</code></pre><p>Evaluation starts at the first clause. The pattern <code class="inline">N</code> is matched against
│ │ │ │  argument 1. The matching succeeds and the guard (<code class="inline">N &gt; 0</code>) is true, thus <code class="inline">N</code> is
│ │ │ │ -bound to 1, and the corresponding body is evaluated:</p><pre><code class="makeup erlang" translate="no"><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="9658700203-1">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="9658700203-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9658700203-2">(</span><span class="n">N</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">bound</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="9658700203-2">)</span><span class="w">
│ │ │ │ -</span><span class="mi">1</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="9658700203-3">(</span><span class="mi">0</span><span class="p" data-group-id="9658700203-3">)</span></code></pre><p>Now, <code class="inline">fact(0)</code> is called, and the function clauses are scanned
│ │ │ │ +bound to 1, and the corresponding body is evaluated:</p><pre><code class="makeup erlang" translate="no"><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="3346850959-1">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="3346850959-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3346850959-2">(</span><span class="n">N</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">bound</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3346850959-2">)</span><span class="w">
│ │ │ │ +</span><span class="mi">1</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="3346850959-3">(</span><span class="mi">0</span><span class="p" data-group-id="3346850959-3">)</span></code></pre><p>Now, <code class="inline">fact(0)</code> is called, and the function clauses are scanned
│ │ │ │  sequentially again. First, the pattern <code class="inline">N</code> is matched against 0. The
│ │ │ │  matching succeeds, but the guard (<code class="inline">N &gt; 0</code>) is false. Second, the
│ │ │ │  pattern <code class="inline">0</code> is matched against the argument <code class="inline">0</code>. The matching succeeds
│ │ │ │  and the body is evaluated:</p><pre><code class="text">1 * fact(0) =&gt;
│ │ │ │  1 * 1 =&gt;
│ │ │ │  1</code></pre><p>Evaluation has succeed and <code class="inline">mod:fact(1)</code> returns 1.</p><p>If <code class="inline">mod:fact/1</code> is called with a negative number as argument, no clause head
│ │ │ │  matches. A <code class="inline">function_clause</code> runtime error occurs.</p><h2 id="tail-recursion" class="section-heading">
│ │ │ │ @@ -78,17 +78,17 @@
│ │ │ │    </a>
│ │ │ │    <span class="text">Tail recursion</span>
│ │ │ │  </h2>
│ │ │ │  <p>If the last expression of a function body is a function call, a
│ │ │ │  <em>tail-recursive call</em> is done. This is to ensure that no system
│ │ │ │  resources, for example, call stack, are consumed. This means that an
│ │ │ │  infinite loop using tail-recursive calls will not exhaust the call
│ │ │ │ -stack and can (in principle) run forever.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="5277657478-1">(</span><span class="n">N</span><span class="p" data-group-id="5277657478-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5277657478-2">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5277657478-3">[</span><span class="n">N</span><span class="p" data-group-id="5277657478-3">]</span><span class="p" data-group-id="5277657478-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="5277657478-4">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="5277657478-4">)</span><span class="p">.</span></code></pre><p>The earlier factorial example is a counter-example. It is not
│ │ │ │ +stack and can (in principle) run forever.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="5932436789-1">(</span><span class="n">N</span><span class="p" data-group-id="5932436789-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5932436789-2">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5932436789-3">[</span><span class="n">N</span><span class="p" data-group-id="5932436789-3">]</span><span class="p" data-group-id="5932436789-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="5932436789-4">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="5932436789-4">)</span><span class="p">.</span></code></pre><p>The earlier factorial example is a counter-example. It is not
│ │ │ │  tail-recursive, since a multiplication is done on the result of the recursive
│ │ │ │  call to <code class="inline">fact(N-1)</code>.</p><h2 id="built-in-functions-bifs" class="section-heading">
│ │ │ │    <a href="#built-in-functions-bifs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Built-In Functions (BIFs)</span>
│ │ │ │  </h2>
│ │ │ │ @@ -96,14 +96,14 @@
│ │ │ │  system. BIFs do things that are difficult or impossible to implement
│ │ │ │  in Erlang. Most of the BIFs belong to module <a href="../../../lib/../erts/doc/html/erlang.html"><code class="inline">erlang</code></a>, but there
│ │ │ │  are also BIFs belonging to a few other modules, for example <a href="../../../lib/stdlib/doc/html/lists.html"><code class="inline">lists</code></a>
│ │ │ │  and <a href="../../../lib/stdlib/doc/html/ets.html"><code class="inline">ets</code></a>.</p><p>The most commonly used BIFs belonging to <a href="../../../lib/../erts/doc/html/erlang.html"><code class="inline">erlang</code></a> are <em>auto-imported</em>. They do
│ │ │ │  not need to be prefixed with the module name. Which BIFs that are auto-imported
│ │ │ │  is specified in the <a href="../../../lib/../erts/doc/html/erlang.html"><code class="inline">erlang</code></a> module in ERTS. For example, standard-type
│ │ │ │  conversion BIFs like <code class="inline">atom_to_list</code> and BIFs allowed in guards can be called
│ │ │ │ -without specifying the module name.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="6141330509-1">(</span><span class="p" data-group-id="6141330509-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6141330509-2">}</span><span class="p" data-group-id="6141330509-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +without specifying the module name.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="1465001904-1">(</span><span class="p" data-group-id="1465001904-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1465001904-2">}</span><span class="p" data-group-id="1465001904-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="6141330509-3">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="6141330509-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="1465001904-3">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="1465001904-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;Erlang&quot;</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/records_macros.xhtml
│ │ │ │ @@ -29,40 +29,40 @@
│ │ │ │  </h2>
│ │ │ │  <p>To illustrate this, the messenger example from the previous section is divided
│ │ │ │  into the following five files:</p><ul><li><p><code class="inline">mess_config.hrl</code></p><p>Header file for configuration data</p></li><li><p><code class="inline">mess_interface.hrl</code></p><p>Interface definitions between the client and the messenger</p></li><li><p><code class="inline">user_interface.erl</code></p><p>Functions for the user interface</p></li><li><p><code class="inline">mess_client.erl</code></p><p>Functions for the client side of the messenger</p></li><li><p><code class="inline">mess_server.erl</code></p><p>Functions for the server side of the messenger</p></li></ul><p>While doing this, the message passing interface between the shell, the client,
│ │ │ │  and the server is cleaned up and is defined using <em>records</em>. Also, <em>macros</em> are
│ │ │ │  introduced:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_config.hrl----</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Configure the location of the server node,</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2522688118-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="2522688118-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2024154779-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="2024154779-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%%----END FILE----</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_interface.hrl----</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Message interface between client and server and client shell for</span><span class="w">
│ │ │ │  </span><span class="c1">%%% messenger program</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%%Messages from Client to server received in server/1 function.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9577261816-1">(</span><span class="ss">logon</span><span class="p">,</span><span class="p" data-group-id="9577261816-2">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="p" data-group-id="9577261816-2">}</span><span class="p" data-group-id="9577261816-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9577261816-3">(</span><span class="ss">message</span><span class="p">,</span><span class="p" data-group-id="9577261816-4">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="9577261816-4">}</span><span class="p" data-group-id="9577261816-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5891102030-1">(</span><span class="ss">logon</span><span class="p">,</span><span class="p" data-group-id="5891102030-2">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="p" data-group-id="5891102030-2">}</span><span class="p" data-group-id="5891102030-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5891102030-3">(</span><span class="ss">message</span><span class="p">,</span><span class="p" data-group-id="5891102030-4">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="5891102030-4">}</span><span class="p" data-group-id="5891102030-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%% {&#39;EXIT&#39;, ClientPid, Reason}  (client terminated or unreachable.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Messages from Server to Client, received in await_result/0 function</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9577261816-5">(</span><span class="ss">abort_client</span><span class="p">,</span><span class="p" data-group-id="9577261816-6">{</span><span class="ss">message</span><span class="p" data-group-id="9577261816-6">}</span><span class="p" data-group-id="9577261816-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5891102030-5">(</span><span class="ss">abort_client</span><span class="p">,</span><span class="p" data-group-id="5891102030-6">{</span><span class="ss">message</span><span class="p" data-group-id="5891102030-6">}</span><span class="p" data-group-id="5891102030-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%% Messages are: user_exists_at_other_node,</span><span class="w">
│ │ │ │  </span><span class="c1">%%%               you_are_not_logged_on</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9577261816-7">(</span><span class="ss">server_reply</span><span class="p">,</span><span class="p" data-group-id="9577261816-8">{</span><span class="ss">message</span><span class="p" data-group-id="9577261816-8">}</span><span class="p" data-group-id="9577261816-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5891102030-7">(</span><span class="ss">server_reply</span><span class="p">,</span><span class="p" data-group-id="5891102030-8">{</span><span class="ss">message</span><span class="p" data-group-id="5891102030-8">}</span><span class="p" data-group-id="5891102030-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%% Messages are: logged_on</span><span class="w">
│ │ │ │  </span><span class="c1">%%%               receiver_not_found</span><span class="w">
│ │ │ │  </span><span class="c1">%%%               sent  (Message has been sent (no guarantee)</span><span class="w">
│ │ │ │  </span><span class="c1">%%% Messages from Server to Client received in client/1 function</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9577261816-9">(</span><span class="ss">message_from</span><span class="p">,</span><span class="p" data-group-id="9577261816-10">{</span><span class="ss">from_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="9577261816-10">}</span><span class="p" data-group-id="9577261816-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5891102030-9">(</span><span class="ss">message_from</span><span class="p">,</span><span class="p" data-group-id="5891102030-10">{</span><span class="ss">from_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="5891102030-10">}</span><span class="p" data-group-id="5891102030-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Messages from shell to Client received in client/1 function</span><span class="w">
│ │ │ │  </span><span class="c1">%%% spawn(mess_client, client, [server_node(), Name])</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9577261816-11">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="9577261816-12">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="9577261816-12">}</span><span class="p" data-group-id="9577261816-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5891102030-11">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="5891102030-12">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="5891102030-12">}</span><span class="p" data-group-id="5891102030-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%% logoff</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%%----END FILE----</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE user_interface.erl----</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% User interface to the messenger program</span><span class="w">
│ │ │ │  </span><span class="c1">%%% login(Name)</span><span class="w">
│ │ │ │  </span><span class="c1">%%%     One user at a time can log in from each Erlang node in the</span><span class="w">
│ │ │ │ @@ -75,177 +75,177 @@
│ │ │ │  </span><span class="c1">%%%     Logs off anybody at that node</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% message(ToName, Message)</span><span class="w">
│ │ │ │  </span><span class="c1">%%%     sends Message to ToName. Error messages if the user of this</span><span class="w">
│ │ │ │  </span><span class="c1">%%%     function is not logged on or if ToName is not logged on at</span><span class="w">
│ │ │ │  </span><span class="c1">%%%     any node.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8723571630-1">(</span><span class="ss">user_interface</span><span class="p" data-group-id="8723571630-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8723571630-2">(</span><span class="p" data-group-id="8723571630-3">[</span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8723571630-3">]</span><span class="p" data-group-id="8723571630-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8723571630-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="8723571630-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8723571630-5">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="8723571630-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8531985176-1">(</span><span class="ss">user_interface</span><span class="p" data-group-id="8531985176-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8531985176-2">(</span><span class="p" data-group-id="8531985176-3">[</span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8531985176-3">]</span><span class="p" data-group-id="8531985176-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8531985176-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="8531985176-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8531985176-5">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="8531985176-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">logon</span><span class="p" data-group-id="8723571630-6">(</span><span class="n">Name</span><span class="p" data-group-id="8723571630-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8723571630-7">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8723571630-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">logon</span><span class="p" data-group-id="8531985176-6">(</span><span class="n">Name</span><span class="p" data-group-id="8531985176-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8531985176-7">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8531985176-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">register</span><span class="p" data-group-id="8723571630-8">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ │ -                     </span><span class="nf">spawn</span><span class="p" data-group-id="8723571630-9">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8723571630-10">[</span><span class="o">?</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8723571630-10">]</span><span class="p" data-group-id="8723571630-9">)</span><span class="p" data-group-id="8723571630-8">)</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="nf">register</span><span class="p" data-group-id="8531985176-8">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ │ +                     </span><span class="nf">spawn</span><span class="p" data-group-id="8531985176-9">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8531985176-10">[</span><span class="o">?</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8531985176-10">]</span><span class="p" data-group-id="8531985176-9">)</span><span class="p" data-group-id="8531985176-8">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">already_logged_on</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">logoff</span><span class="p" data-group-id="8723571630-11">(</span><span class="p" data-group-id="8723571630-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">logoff</span><span class="p" data-group-id="8531985176-11">(</span><span class="p" data-group-id="8531985176-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">logoff</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">message</span><span class="p" data-group-id="8723571630-12">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8723571630-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8723571630-13">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8723571630-13">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ │ +</span><span class="nf">message</span><span class="p" data-group-id="8531985176-12">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8531985176-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8531985176-13">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8531985176-13">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">not_logged_on</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="8723571630-14">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="8723571630-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="8531985176-14">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="8531985176-14">}</span><span class="p">,</span><span class="w">
│ │ │ │               </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%%----END FILE----</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_client.erl----</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% The client process which runs on each user node</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2783846407-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="2783846407-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2783846407-2">(</span><span class="p" data-group-id="2783846407-3">[</span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2783846407-3">]</span><span class="p" data-group-id="2783846407-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="2783846407-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="2783846407-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="2783846407-5">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="2783846407-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2783846407-6">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="2783846407-6">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="2783846407-7">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="2783846407-8">(</span><span class="p" data-group-id="2783846407-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="2783846407-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">await_result</span><span class="p" data-group-id="2783846407-9">(</span><span class="p" data-group-id="2783846407-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="2783846407-10">(</span><span class="n">Server_Node</span><span class="p" data-group-id="2783846407-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0944523111-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0944523111-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0944523111-2">(</span><span class="p" data-group-id="0944523111-3">[</span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0944523111-3">]</span><span class="p" data-group-id="0944523111-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0944523111-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="0944523111-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="0944523111-5">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0944523111-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0944523111-6">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0944523111-6">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="0944523111-7">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="0944523111-8">(</span><span class="p" data-group-id="0944523111-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="0944523111-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">await_result</span><span class="p" data-group-id="0944523111-9">(</span><span class="p" data-group-id="0944523111-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="0944523111-10">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0944523111-10">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="2783846407-11">(</span><span class="n">Server_Node</span><span class="p" data-group-id="2783846407-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="0944523111-11">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0944523111-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">logoff</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="2783846407-12">(</span><span class="ss">normal</span><span class="p" data-group-id="2783846407-12">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="2783846407-13">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="2783846407-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="2783846407-14">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="2783846407-14">}</span><span class="w"> </span><span class="o">!</span><span class="w">
│ │ │ │ -                </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="2783846407-15">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="2783846407-16">(</span><span class="p" data-group-id="2783846407-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="2783846407-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">await_result</span><span class="p" data-group-id="2783846407-17">(</span><span class="p" data-group-id="2783846407-17">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="2783846407-18">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2783846407-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2783846407-19">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2783846407-20">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2783846407-20">]</span><span class="p" data-group-id="2783846407-19">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0944523111-12">(</span><span class="ss">normal</span><span class="p" data-group-id="0944523111-12">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="0944523111-13">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="0944523111-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="0944523111-14">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0944523111-14">}</span><span class="w"> </span><span class="o">!</span><span class="w">
│ │ │ │ +                </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="0944523111-15">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="0944523111-16">(</span><span class="p" data-group-id="0944523111-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="0944523111-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">await_result</span><span class="p" data-group-id="0944523111-17">(</span><span class="p" data-group-id="0944523111-17">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0944523111-18">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0944523111-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0944523111-19">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944523111-20">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0944523111-20">]</span><span class="p" data-group-id="0944523111-19">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="2783846407-21">(</span><span class="n">Server_Node</span><span class="p" data-group-id="2783846407-21">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="0944523111-21">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0944523111-21">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% wait for a response from the server</span><span class="w">
│ │ │ │ -</span><span class="nf">await_result</span><span class="p" data-group-id="2783846407-22">(</span><span class="p" data-group-id="2783846407-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">await_result</span><span class="p" data-group-id="0944523111-22">(</span><span class="p" data-group-id="0944523111-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="2783846407-23">{</span><span class="ss">message</span><span class="o">=</span><span class="n">Why</span><span class="p" data-group-id="2783846407-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2783846407-24">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2783846407-25">[</span><span class="n">Why</span><span class="p" data-group-id="2783846407-25">]</span><span class="p" data-group-id="2783846407-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="2783846407-26">(</span><span class="ss">normal</span><span class="p" data-group-id="2783846407-26">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="2783846407-27">{</span><span class="ss">message</span><span class="o">=</span><span class="n">What</span><span class="p" data-group-id="2783846407-27">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2783846407-28">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2783846407-29">[</span><span class="n">What</span><span class="p" data-group-id="2783846407-29">]</span><span class="p" data-group-id="2783846407-28">)</span><span class="w">
│ │ │ │ +        </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="0944523111-23">{</span><span class="ss">message</span><span class="o">=</span><span class="n">Why</span><span class="p" data-group-id="0944523111-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0944523111-24">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944523111-25">[</span><span class="n">Why</span><span class="p" data-group-id="0944523111-25">]</span><span class="p" data-group-id="0944523111-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0944523111-26">(</span><span class="ss">normal</span><span class="p" data-group-id="0944523111-26">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="0944523111-27">{</span><span class="ss">message</span><span class="o">=</span><span class="n">What</span><span class="p" data-group-id="0944523111-27">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0944523111-28">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944523111-29">[</span><span class="n">What</span><span class="p" data-group-id="0944523111-29">]</span><span class="p" data-group-id="0944523111-28">)</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2783846407-30">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2783846407-31">[</span><span class="p" data-group-id="2783846407-31">]</span><span class="p" data-group-id="2783846407-30">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="2783846407-32">(</span><span class="ss">timeout</span><span class="p" data-group-id="2783846407-32">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0944523111-30">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0944523111-31">[</span><span class="p" data-group-id="0944523111-31">]</span><span class="p" data-group-id="0944523111-30">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0944523111-32">(</span><span class="ss">timeout</span><span class="p" data-group-id="0944523111-32">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%%----END FILE---</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_server.erl----</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% This is the server process of the messenger service</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1601980861-1">(</span><span class="ss">mess_server</span><span class="p" data-group-id="1601980861-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1601980861-2">(</span><span class="p" data-group-id="1601980861-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1601980861-3">]</span><span class="p" data-group-id="1601980861-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="1601980861-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="1601980861-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="1601980861-5">(</span><span class="p" data-group-id="1601980861-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="1601980861-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="1601980861-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">server</span><span class="p" data-group-id="1601980861-7">(</span><span class="p" data-group-id="1601980861-8">[</span><span class="p" data-group-id="1601980861-8">]</span><span class="p" data-group-id="1601980861-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8412865549-1">(</span><span class="ss">mess_server</span><span class="p" data-group-id="8412865549-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8412865549-2">(</span><span class="p" data-group-id="8412865549-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8412865549-3">]</span><span class="p" data-group-id="8412865549-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8412865549-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="8412865549-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="8412865549-5">(</span><span class="p" data-group-id="8412865549-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="8412865549-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8412865549-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">server</span><span class="p" data-group-id="8412865549-7">(</span><span class="p" data-group-id="8412865549-8">[</span><span class="p" data-group-id="8412865549-8">]</span><span class="p" data-group-id="8412865549-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% the user list has the format [{ClientPid1, Name1},{ClientPid22, Name2},...]</span><span class="w">
│ │ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="1601980861-9">(</span><span class="n">User_List</span><span class="p" data-group-id="1601980861-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1601980861-10">(</span><span class="s">&quot;User list = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1601980861-11">[</span><span class="n">User_List</span><span class="p" data-group-id="1601980861-11">]</span><span class="p" data-group-id="1601980861-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="8412865549-9">(</span><span class="n">User_List</span><span class="p" data-group-id="8412865549-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8412865549-10">(</span><span class="s">&quot;User list = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8412865549-11">[</span><span class="n">User_List</span><span class="p" data-group-id="8412865549-11">]</span><span class="p" data-group-id="8412865549-10">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="1601980861-12">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="1601980861-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="1601980861-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="1601980861-14">(</span><span class="n">New_User_List</span><span class="p" data-group-id="1601980861-14">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1601980861-15">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="1601980861-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="1601980861-16">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="1601980861-17">(</span><span class="n">New_User_List</span><span class="p" data-group-id="1601980861-17">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="1601980861-18">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="1601980861-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="1601980861-19">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-19">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="1601980861-20">(</span><span class="n">User_List</span><span class="p" data-group-id="1601980861-20">)</span><span class="w">
│ │ │ │ +        </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="8412865549-12">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="8412865549-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="8412865549-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="8412865549-14">(</span><span class="n">New_User_List</span><span class="p" data-group-id="8412865549-14">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8412865549-15">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="8412865549-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="8412865549-16">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="8412865549-17">(</span><span class="n">New_User_List</span><span class="p" data-group-id="8412865549-17">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="8412865549-18">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="8412865549-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="8412865549-19">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-19">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="8412865549-20">(</span><span class="n">User_List</span><span class="p" data-group-id="8412865549-20">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Start the server</span><span class="w">
│ │ │ │ -</span><span class="nf">start_server</span><span class="p" data-group-id="1601980861-21">(</span><span class="p" data-group-id="1601980861-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="1601980861-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1601980861-23">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1601980861-24">[</span><span class="p" data-group-id="1601980861-24">]</span><span class="p" data-group-id="1601980861-23">)</span><span class="p" data-group-id="1601980861-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_server</span><span class="p" data-group-id="8412865549-21">(</span><span class="p" data-group-id="8412865549-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="8412865549-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="8412865549-23">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8412865549-24">[</span><span class="p" data-group-id="8412865549-24">]</span><span class="p" data-group-id="8412865549-23">)</span><span class="p" data-group-id="8412865549-22">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server adds a new user to the user list</span><span class="w">
│ │ │ │ -</span><span class="nf">server_logon</span><span class="p" data-group-id="1601980861-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_logon</span><span class="p" data-group-id="8412865549-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% check if logged on anywhere else</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="1601980861-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="8412865549-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="1601980861-27">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="1601980861-27">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="8412865549-27">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="8412865549-27">}</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">User_List</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="1601980861-28">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">logged_on</span><span class="p" data-group-id="1601980861-28">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">link</span><span class="p" data-group-id="1601980861-29">(</span><span class="n">From</span><span class="p" data-group-id="1601980861-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="1601980861-30">[</span><span class="p" data-group-id="1601980861-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="1601980861-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="8412865549-28">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">logged_on</span><span class="p" data-group-id="8412865549-28">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">link</span><span class="p" data-group-id="8412865549-29">(</span><span class="n">From</span><span class="p" data-group-id="8412865549-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="8412865549-30">[</span><span class="p" data-group-id="8412865549-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8412865549-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server deletes a user from the user list</span><span class="w">
│ │ │ │ -</span><span class="nf">server_logoff</span><span class="p" data-group-id="1601980861-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="1601980861-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-33">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">server_logoff</span><span class="p" data-group-id="8412865549-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="8412865549-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-33">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server transfers a message between user</span><span class="w">
│ │ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="1601980861-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="8412865549-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% check that the user is logged on and who he is</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="1601980861-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8412865549-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="1601980861-36">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="1601980861-36">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1601980861-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1601980861-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="1601980861-38">}</span><span class="p" data-group-id="1601980861-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="1601980861-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-39">)</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="8412865549-36">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="8412865549-36">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8412865549-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8412865549-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8412865549-38">}</span><span class="p" data-group-id="8412865549-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="8412865549-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-39">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%% If the user exists, send the message</span><span class="w">
│ │ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="1601980861-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="8412865549-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Find the receiver and send the message</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="1601980861-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1601980861-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8412865549-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8412865549-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="1601980861-42">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">receiver_not_found</span><span class="p" data-group-id="1601980861-42">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1601980861-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1601980861-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="1601980861-44">}</span><span class="p" data-group-id="1601980861-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_from</span><span class="p" data-group-id="1601980861-45">{</span><span class="ss">from_name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="1601980861-45">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w">  </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="1601980861-46">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">sent</span><span class="p" data-group-id="1601980861-46">}</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="8412865549-42">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">receiver_not_found</span><span class="p" data-group-id="8412865549-42">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8412865549-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8412865549-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="8412865549-44">}</span><span class="p" data-group-id="8412865549-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_from</span><span class="p" data-group-id="8412865549-45">{</span><span class="ss">from_name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="8412865549-45">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w">  </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="8412865549-46">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">sent</span><span class="p" data-group-id="8412865549-46">}</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%%----END FILE---</span></code></pre><h2 id="header-files" class="section-heading">
│ │ │ │    <a href="#header-files" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Header Files</span>
│ │ │ │  </h2>
│ │ │ │  <p>As shown above, some files have extension <code class="inline">.hrl</code>. These are header files that
│ │ │ │ -are included in the <code class="inline">.erl</code> files by:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="3178849141-1">(</span><span class="s">&quot;File_Name&quot;</span><span class="p" data-group-id="3178849141-1">)</span><span class="p">.</span></code></pre><p>for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0746806496-1">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="0746806496-1">)</span><span class="p">.</span></code></pre><p>In the case above the file is fetched from the same directory as all the other
│ │ │ │ +are included in the <code class="inline">.erl</code> files by:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="2270891936-1">(</span><span class="s">&quot;File_Name&quot;</span><span class="p" data-group-id="2270891936-1">)</span><span class="p">.</span></code></pre><p>for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0486465723-1">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="0486465723-1">)</span><span class="p">.</span></code></pre><p>In the case above the file is fetched from the same directory as all the other
│ │ │ │  files in the messenger example. (<em>manual</em>).</p><p>.hrl files can contain any valid Erlang code but are most often used for record
│ │ │ │  and macro definitions.</p><h2 id="records" class="section-heading">
│ │ │ │    <a href="#records" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Records</span>
│ │ │ │  </h2>
│ │ │ │ -<p>A record is defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5554112138-1">(</span><span class="ss">name_of_record</span><span class="p">,</span><span class="p" data-group-id="5554112138-2">{</span><span class="ss">field_name1</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name2</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5554112138-2">}</span><span class="p" data-group-id="5554112138-1">)</span><span class="p">.</span></code></pre><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="0537727771-1">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="0537727771-2">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="0537727771-2">}</span><span class="p" data-group-id="0537727771-1">)</span><span class="p">.</span></code></pre><p>This is equivalent to:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0039069533-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To_Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0039069533-1">}</span></code></pre><p>Creating a record is best illustrated by an example:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="7622732966-1">{</span><span class="ss">message</span><span class="o">=</span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="ss">fred</span><span class="p">)</span></code></pre><p>This creates:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9886334863-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="9886334863-1">}</span></code></pre><p>Notice that you do not have to worry about the order you assign values to the
│ │ │ │ +<p>A record is defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2820653938-1">(</span><span class="ss">name_of_record</span><span class="p">,</span><span class="p" data-group-id="2820653938-2">{</span><span class="ss">field_name1</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name2</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2820653938-2">}</span><span class="p" data-group-id="2820653938-1">)</span><span class="p">.</span></code></pre><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7359894057-1">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="7359894057-2">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="7359894057-2">}</span><span class="p" data-group-id="7359894057-1">)</span><span class="p">.</span></code></pre><p>This is equivalent to:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1818065093-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To_Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="1818065093-1">}</span></code></pre><p>Creating a record is best illustrated by an example:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="9630074053-1">{</span><span class="ss">message</span><span class="o">=</span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="ss">fred</span><span class="p">)</span></code></pre><p>This creates:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2618156088-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="2618156088-1">}</span></code></pre><p>Notice that you do not have to worry about the order you assign values to the
│ │ │ │  various parts of the records when you create it. The advantage of using records
│ │ │ │  is that by placing their definitions in header files you can conveniently define
│ │ │ │  interfaces that are easy to change. For example, if you want to add a new field
│ │ │ │  to the record, you only have to change the code where the new field is used and
│ │ │ │  not at every place the record is referred to. If you leave out a field when
│ │ │ │  creating a record, it gets the value of the atom <code class="inline">undefined</code>. (<em>manual</em>)</p><p>Pattern matching with records is very similar to creating records. For example,
│ │ │ │ -inside a <code class="inline">case</code> or <code class="inline">receive</code>:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="0789348723-1">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="0789348723-1">}</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>This is the same as:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1960356927-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="1960356927-1">}</span></code></pre><h2 id="macros" class="section-heading">
│ │ │ │ +inside a <code class="inline">case</code> or <code class="inline">receive</code>:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="5002641876-1">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="5002641876-1">}</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>This is the same as:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6369874091-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="6369874091-1">}</span></code></pre><h2 id="macros" class="section-heading">
│ │ │ │    <a href="#macros" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Macros</span>
│ │ │ │  </h2>
│ │ │ │  <p>Another thing that has been added to the messenger is a macro. The file
│ │ │ │  <code class="inline">mess_config.hrl</code> contains the definition:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Configure the location of the server node,</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1454840943-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="1454840943-1">)</span><span class="p">.</span></code></pre><p>This file is included in <code class="inline">mess_server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="6335202565-1">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="6335202565-1">)</span><span class="p">.</span></code></pre><p>Every occurrence of <code class="inline">?server_node</code> in <code class="inline">mess_server.erl</code> is now replaced by
│ │ │ │ -<code class="inline">messenger@super</code>.</p><p>A macro is also used when spawning the server process:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="9558742187-1">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9558742187-2">[</span><span class="p" data-group-id="9558742187-2">]</span><span class="p" data-group-id="9558742187-1">)</span></code></pre><p>This is a standard macro (that is, defined by the system, not by the user).
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7447030113-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="7447030113-1">)</span><span class="p">.</span></code></pre><p>This file is included in <code class="inline">mess_server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0463332670-1">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="0463332670-1">)</span><span class="p">.</span></code></pre><p>Every occurrence of <code class="inline">?server_node</code> in <code class="inline">mess_server.erl</code> is now replaced by
│ │ │ │ +<code class="inline">messenger@super</code>.</p><p>A macro is also used when spawning the server process:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="8970642682-1">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8970642682-2">[</span><span class="p" data-group-id="8970642682-2">]</span><span class="p" data-group-id="8970642682-1">)</span></code></pre><p>This is a standard macro (that is, defined by the system, not by the user).
│ │ │ │  <code class="inline">?MODULE</code> is always replaced by the name of the current module (that is, the
│ │ │ │  <code class="inline">-module</code> definition near the start of the file). There are more advanced ways
│ │ │ │  of using macros with, for example, <a href="macros.xhtml#defining-and-using-macros">parameters</a>.</p><p>The three Erlang (<code class="inline">.erl</code>) files in the messenger example are individually
│ │ │ │  compiled into object code file (<code class="inline">.beam</code>). The Erlang system loads and links
│ │ │ │  these files into the system when they are referred to during execution of the
│ │ │ │  code. In this case, they are simply put in our current working directory (that
│ │ │ │  is, the place you have done &quot;cd&quot; to). There are ways of putting the <code class="inline">.beam</code>
│ │ │ ├── OEBPS/prog_ex_records.xhtml
│ │ │ │ @@ -27,105 +27,105 @@
│ │ │ │    <span class="text">Records and Tuples</span>
│ │ │ │  </h2>
│ │ │ │  <p>The main advantage of using records rather than tuples is that fields in a
│ │ │ │  record are accessed by name, whereas fields in a tuple are accessed by position.
│ │ │ │  To illustrate these differences, suppose that you want to represent a person
│ │ │ │  with the tuple <code class="inline">{Name, Address, Phone}</code>.</p><p>To write functions that manipulate this data, remember the following:</p><ul><li>The <code class="inline">Name</code> field is the first element of the tuple.</li><li>The <code class="inline">Address</code> field is the second element.</li><li>The <code class="inline">Phone</code> field is the third element.</li></ul><p>For example, to extract data from a variable <code class="inline">P</code> that contains such a tuple, you
│ │ │ │  can write the following code and then use pattern matching to extract the
│ │ │ │ -relevant fields:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="8619586400-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="8619586400-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="8619586400-2">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="8619586400-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +relevant fields:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="4404742203-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="4404742203-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="4404742203-2">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="4404742203-2">)</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Such code is difficult to read and understand, and errors occur if the numbering
│ │ │ │  of the elements in the tuple is wrong. If the data representation of the fields
│ │ │ │  is changed, by re-ordering, adding, or removing fields, all references to the
│ │ │ │  person tuple must be checked and possibly modified.</p><p>Records allow references to the fields by name, instead of by position. In the
│ │ │ │ -following example, a record instead of a tuple is used to store the data:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1153782000-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1153782000-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="1153782000-2">}</span><span class="p" data-group-id="1153782000-1">)</span><span class="p">.</span></code></pre><p>This enables references to the fields of the record by name. For example, if <code class="inline">P</code>
│ │ │ │ +following example, a record instead of a tuple is used to store the data:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5472657021-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5472657021-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="5472657021-2">}</span><span class="p" data-group-id="5472657021-1">)</span><span class="p">.</span></code></pre><p>This enables references to the fields of the record by name. For example, if <code class="inline">P</code>
│ │ │ │  is a variable whose value is a <code class="inline">person</code> record, the following code access the
│ │ │ │  name and address fields of the records:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="n">Address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">address</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Internally, records are represented using tagged tuples:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6612655917-1">{</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p" data-group-id="6612655917-1">}</span></code></pre><h2 id="defining-a-record" class="section-heading">
│ │ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Internally, records are represented using tagged tuples:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2369099179-1">{</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p" data-group-id="2369099179-1">}</span></code></pre><h2 id="defining-a-record" class="section-heading">
│ │ │ │    <a href="#defining-a-record" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Defining a Record</span>
│ │ │ │  </h2>
│ │ │ │  <p>This following definition of a <code class="inline">person</code> is used in several examples in this
│ │ │ │  section. Three fields are included, <code class="inline">name</code>, <code class="inline">phone</code>, and <code class="inline">address</code>. The default
│ │ │ │  values for <code class="inline">name</code> and <code class="inline">phone</code> is &quot;&quot; and [], respectively. The default value for
│ │ │ │  <code class="inline">address</code> is the atom <code class="inline">undefined</code>, since no default value is supplied for this
│ │ │ │ -field:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7578019158-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7578019158-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7578019158-3">[</span><span class="p" data-group-id="7578019158-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="7578019158-2">}</span><span class="p" data-group-id="7578019158-1">)</span><span class="p">.</span></code></pre><p>The record must be defined in the shell to enable use of the record syntax in
│ │ │ │ -the examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">rd</span><span class="p" data-group-id="9809049864-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9809049864-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9809049864-3">[</span><span class="p" data-group-id="9809049864-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="9809049864-2">}</span><span class="p" data-group-id="9809049864-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +field:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7886546784-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7886546784-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7886546784-3">[</span><span class="p" data-group-id="7886546784-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="7886546784-2">}</span><span class="p" data-group-id="7886546784-1">)</span><span class="p">.</span></code></pre><p>The record must be defined in the shell to enable use of the record syntax in
│ │ │ │ +the examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">rd</span><span class="p" data-group-id="7093474364-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7093474364-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7093474364-3">[</span><span class="p" data-group-id="7093474364-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="7093474364-2">}</span><span class="p" data-group-id="7093474364-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">person</span></code></pre><p>This is because record definitions are only available at compile time, not at
│ │ │ │  runtime. For details on records in the shell, see the <a href="../../../lib/stdlib/doc/html/shell.html"><code class="inline">shell</code></a> manual page in
│ │ │ │  STDLIB.</p><h2 id="creating-a-record" class="section-heading">
│ │ │ │    <a href="#creating-a-record" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Creating a Record</span>
│ │ │ │  </h2>
│ │ │ │ -<p>A new <code class="inline">person</code> record is created as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0234775774-1">{</span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="0234775774-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0234775774-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="0234775774-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0234775774-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0234775774-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0234775774-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="0234775774-3">}</span></code></pre><p>As the <code class="inline">address</code> field was omitted, its default value is used.</p><p>From Erlang 5.1/OTP R8B, a value to all fields in a record can be set with the
│ │ │ │ -special field <code class="inline">_</code>. <code class="inline">_</code> means &quot;all fields not explicitly specified&quot;.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4755560023-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="4755560023-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4755560023-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="4755560023-2">}</span></code></pre><p>It is primarily intended to be used in <a href="../../../lib/stdlib/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a> and
│ │ │ │ +<p>A new <code class="inline">person</code> record is created as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5340469408-1">{</span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="5340469408-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5340469408-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="5340469408-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5340469408-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5340469408-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5340469408-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="5340469408-3">}</span></code></pre><p>As the <code class="inline">address</code> field was omitted, its default value is used.</p><p>From Erlang 5.1/OTP R8B, a value to all fields in a record can be set with the
│ │ │ │ +special field <code class="inline">_</code>. <code class="inline">_</code> means &quot;all fields not explicitly specified&quot;.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3614315462-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="3614315462-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3614315462-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="3614315462-2">}</span></code></pre><p>It is primarily intended to be used in <a href="../../../lib/stdlib/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a> and
│ │ │ │  <a href="../../../lib/mnesia/doc/html/mnesia.html#match_object/3"><code class="inline">mnesia:match_object/3</code></a>, to set record fields to the atom <code class="inline">'_'</code>. (This is a
│ │ │ │  wildcard in <a href="../../../lib/stdlib/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a>.)</p><h2 id="accessing-a-record-field" class="section-heading">
│ │ │ │    <a href="#accessing-a-record-field" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Accessing a Record Field</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The following example shows how to access a record field:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1743100029-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1743100029-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1743100029-2">]</span><span class="p" data-group-id="1743100029-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1743100029-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1743100029-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1743100029-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="1743100029-3">}</span><span class="gp unselectable">
│ │ │ │ +<p>The following example shows how to access a record field:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4131316973-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4131316973-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4131316973-2">]</span><span class="p" data-group-id="4131316973-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4131316973-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4131316973-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4131316973-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="4131316973-3">}</span><span class="gp unselectable">
│ │ │ │  &gt; </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;Joe&quot;</span></code></pre><h2 id="updating-a-record" class="section-heading">
│ │ │ │    <a href="#updating-a-record" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Updating a Record</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The following example shows how to update a record:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3489971550-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="3489971550-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3489971550-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="3489971550-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3489971550-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3489971550-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3489971550-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="3489971550-3">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P1</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3489971550-5">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="3489971550-5">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3489971550-6">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3489971550-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3489971550-7">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="3489971550-6">}</span></code></pre><h2 id="type-testing" class="section-heading">
│ │ │ │ +<p>The following example shows how to update a record:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9463983558-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="9463983558-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9463983558-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="9463983558-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9463983558-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9463983558-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9463983558-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="9463983558-3">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P1</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9463983558-5">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="9463983558-5">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9463983558-6">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9463983558-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9463983558-7">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="9463983558-6">}</span></code></pre><h2 id="type-testing" class="section-heading">
│ │ │ │    <a href="#type-testing" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Type Testing</span>
│ │ │ │  </h2>
│ │ │ │  <p>The following example shows that the guard succeeds if <code class="inline">P</code> is record of type
│ │ │ │ -<code class="inline">person</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="5777560661-1">(</span><span class="n">P</span><span class="p" data-group-id="5777560661-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="5777560661-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="5777560661-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">a_person</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="5777560661-3">(</span><span class="p">_</span><span class="p" data-group-id="5777560661-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">not_a_person</span><span class="p">.</span></code></pre><h2 id="pattern-matching" class="section-heading">
│ │ │ │ +<code class="inline">person</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="0560135131-1">(</span><span class="n">P</span><span class="p" data-group-id="0560135131-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="0560135131-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="0560135131-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">a_person</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="0560135131-3">(</span><span class="p">_</span><span class="p" data-group-id="0560135131-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">not_a_person</span><span class="p">.</span></code></pre><h2 id="pattern-matching" class="section-heading">
│ │ │ │    <a href="#pattern-matching" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Pattern Matching</span>
│ │ │ │  </h2>
│ │ │ │  <p>Matching can be used in combination with records, as shown in the following
│ │ │ │ -example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4079067800-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="4079067800-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="4079067800-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="4079067800-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4079067800-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4079067800-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="4079067800-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="4079067800-3">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4079067800-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4079067800-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P3</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">.</span><span class="w">
│ │ │ │ +example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6862388415-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="6862388415-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="6862388415-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="6862388415-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6862388415-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6862388415-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="6862388415-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="6862388415-3">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6862388415-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="6862388415-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P3</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;Joe&quot;</span></code></pre><p>The following function takes a list of <code class="inline">person</code> records and searches for the
│ │ │ │ -phone number of a person with a particular name:</p><pre><code class="makeup erlang" translate="no"><span class="nf">find_phone</span><span class="p" data-group-id="7567875173-1">(</span><span class="p" data-group-id="7567875173-2">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="7567875173-3">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="n">Phone</span><span class="p" data-group-id="7567875173-3">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7567875173-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="7567875173-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7567875173-4">{</span><span class="ss">found</span><span class="p">,</span><span class="w">  </span><span class="n">Phone</span><span class="p" data-group-id="7567875173-4">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">find_phone</span><span class="p" data-group-id="7567875173-5">(</span><span class="p" data-group-id="7567875173-6">[</span><span class="p">_</span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7567875173-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="7567875173-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">find_phone</span><span class="p" data-group-id="7567875173-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="7567875173-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">find_phone</span><span class="p" data-group-id="7567875173-8">(</span><span class="p" data-group-id="7567875173-9">[</span><span class="p" data-group-id="7567875173-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="7567875173-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +phone number of a person with a particular name:</p><pre><code class="makeup erlang" translate="no"><span class="nf">find_phone</span><span class="p" data-group-id="3807165679-1">(</span><span class="p" data-group-id="3807165679-2">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3807165679-3">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="n">Phone</span><span class="p" data-group-id="3807165679-3">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="3807165679-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3807165679-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3807165679-4">{</span><span class="ss">found</span><span class="p">,</span><span class="w">  </span><span class="n">Phone</span><span class="p" data-group-id="3807165679-4">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">find_phone</span><span class="p" data-group-id="3807165679-5">(</span><span class="p" data-group-id="3807165679-6">[</span><span class="p">_</span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="3807165679-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3807165679-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">find_phone</span><span class="p" data-group-id="3807165679-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3807165679-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">find_phone</span><span class="p" data-group-id="3807165679-8">(</span><span class="p" data-group-id="3807165679-9">[</span><span class="p" data-group-id="3807165679-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3807165679-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">not_found</span><span class="p">.</span></code></pre><p>The fields referred to in the pattern can be given in any order.</p><h2 id="nested-records" class="section-heading">
│ │ │ │    <a href="#nested-records" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Nested Records</span>
│ │ │ │  </h2>
│ │ │ │  <p>The value of a field in a record can be an instance of a record. Retrieval of
│ │ │ │  nested data can be done stepwise, or in a single step, as shown in the following
│ │ │ │ -example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9329579138-1">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9329579138-2">{</span><span class="ss">first</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">last</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Ericsson&quot;</span><span class="p" data-group-id="9329579138-2">}</span><span class="p" data-group-id="9329579138-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9329579138-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9329579138-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="9329579138-5">{</span><span class="p" data-group-id="9329579138-5">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p" data-group-id="9329579138-4">}</span><span class="p" data-group-id="9329579138-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9880080926-1">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9880080926-2">{</span><span class="ss">first</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">last</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Ericsson&quot;</span><span class="p" data-group-id="9880080926-2">}</span><span class="p" data-group-id="9880080926-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9880080926-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9880080926-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="9880080926-5">{</span><span class="p" data-group-id="9880080926-5">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p" data-group-id="9880080926-4">}</span><span class="p" data-group-id="9880080926-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">demo</span><span class="p" data-group-id="9329579138-6">(</span><span class="p" data-group-id="9329579138-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9329579138-7">{</span><span class="ss">name</span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="9329579138-8">{</span><span class="ss">first</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">last</span><span class="o">=</span><span class="s">&quot;Virding&quot;</span><span class="p" data-group-id="9329579138-8">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="mi">123</span><span class="p" data-group-id="9329579138-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="n">First</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9329579138-9">(</span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="9329579138-9">)</span><span class="o">#</span><span class="ss">name</span><span class="p">.</span><span class="ss">first</span><span class="p">.</span></code></pre><p>Here, <code class="inline">demo()</code> evaluates to <code class="inline">&quot;Robert&quot;</code>.</p><h2 id="a-longer-example" class="section-heading">
│ │ │ │ +</span><span class="nf">demo</span><span class="p" data-group-id="9880080926-6">(</span><span class="p" data-group-id="9880080926-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9880080926-7">{</span><span class="ss">name</span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="9880080926-8">{</span><span class="ss">first</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">last</span><span class="o">=</span><span class="s">&quot;Virding&quot;</span><span class="p" data-group-id="9880080926-8">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="mi">123</span><span class="p" data-group-id="9880080926-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="n">First</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9880080926-9">(</span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="9880080926-9">)</span><span class="o">#</span><span class="ss">name</span><span class="p">.</span><span class="ss">first</span><span class="p">.</span></code></pre><p>Here, <code class="inline">demo()</code> evaluates to <code class="inline">&quot;Robert&quot;</code>.</p><h2 id="a-longer-example" class="section-heading">
│ │ │ │    <a href="#a-longer-example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">A Longer Example</span>
│ │ │ │  </h2>
│ │ │ │  <p>Comments are embedded in the following example:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% File: person.hrl</span><span class="w">
│ │ │ │  
│ │ │ │ @@ -135,44 +135,44 @@
│ │ │ │  </span><span class="c1">%%    name:  A string (default is undefined).</span><span class="w">
│ │ │ │  </span><span class="c1">%%    age:   An integer (default is undefined).</span><span class="w">
│ │ │ │  </span><span class="c1">%%    phone: A list of integers (default is []).</span><span class="w">
│ │ │ │  </span><span class="c1">%%    dict:  A dictionary containing various information</span><span class="w">
│ │ │ │  </span><span class="c1">%%           about the person.</span><span class="w">
│ │ │ │  </span><span class="c1">%%           A {Key, Value} list (default is the empty list).</span><span class="w">
│ │ │ │  </span><span class="c1">%%------------------------------------------------------------</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3371046566-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3371046566-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3371046566-3">[</span><span class="p" data-group-id="3371046566-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3371046566-4">[</span><span class="p" data-group-id="3371046566-4">]</span><span class="p" data-group-id="3371046566-2">}</span><span class="p" data-group-id="3371046566-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4357097441-1">(</span><span class="ss">person</span><span class="p" data-group-id="4357097441-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="4357097441-2">(</span><span class="s">&quot;person.hrl&quot;</span><span class="p" data-group-id="4357097441-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="4357097441-3">(</span><span class="ss">export_all</span><span class="p" data-group-id="4357097441-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% For test purposes only.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4388462500-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4388462500-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4388462500-3">[</span><span class="p" data-group-id="4388462500-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4388462500-4">[</span><span class="p" data-group-id="4388462500-4">]</span><span class="p" data-group-id="4388462500-2">}</span><span class="p" data-group-id="4388462500-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3468851277-1">(</span><span class="ss">person</span><span class="p" data-group-id="3468851277-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="3468851277-2">(</span><span class="s">&quot;person.hrl&quot;</span><span class="p" data-group-id="3468851277-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="3468851277-3">(</span><span class="ss">export_all</span><span class="p" data-group-id="3468851277-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% For test purposes only.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% This creates an instance of a person.</span><span class="w">
│ │ │ │  </span><span class="c1">%%   Note: The phone number is not supplied so the</span><span class="w">
│ │ │ │  </span><span class="c1">%%         default value [] will be used.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="4357097441-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="4357097441-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4357097441-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ │ -           </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4357097441-6">[</span><span class="p" data-group-id="4357097441-7">{</span><span class="ss">computer_knowledge</span><span class="p">,</span><span class="w"> </span><span class="ss">excellent</span><span class="p" data-group-id="4357097441-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                   </span><span class="p" data-group-id="4357097441-8">{</span><span class="ss">drinks</span><span class="p">,</span><span class="w"> </span><span class="ss">coke</span><span class="p" data-group-id="4357097441-8">}</span><span class="p" data-group-id="4357097441-6">]</span><span class="p" data-group-id="4357097441-5">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="3468851277-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="3468851277-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3468851277-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ │ +           </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3468851277-6">[</span><span class="p" data-group-id="3468851277-7">{</span><span class="ss">computer_knowledge</span><span class="p">,</span><span class="w"> </span><span class="ss">excellent</span><span class="p" data-group-id="3468851277-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                   </span><span class="p" data-group-id="3468851277-8">{</span><span class="ss">drinks</span><span class="p">,</span><span class="w"> </span><span class="ss">coke</span><span class="p" data-group-id="3468851277-8">}</span><span class="p" data-group-id="3468851277-6">]</span><span class="p" data-group-id="3468851277-5">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% This demonstrates matching in arguments</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">print</span><span class="p" data-group-id="4357097441-9">(</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4357097441-10">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="4357097441-10">}</span><span class="p" data-group-id="4357097441-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4357097441-11">(</span><span class="s">&quot;Name: </span><span class="si">~s</span><span class="s">, Age: </span><span class="si">~w</span><span class="s">, Phone: </span><span class="si">~w</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="w">
│ │ │ │ -            </span><span class="s">&quot;Dictionary: </span><span class="si">~w</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4357097441-12">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="4357097441-12">]</span><span class="p" data-group-id="4357097441-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">print</span><span class="p" data-group-id="3468851277-9">(</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3468851277-10">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="3468851277-10">}</span><span class="p" data-group-id="3468851277-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3468851277-11">(</span><span class="s">&quot;Name: </span><span class="si">~s</span><span class="s">, Age: </span><span class="si">~w</span><span class="s">, Phone: </span><span class="si">~w</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="w">
│ │ │ │ +            </span><span class="s">&quot;Dictionary: </span><span class="si">~w</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3468851277-12">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="3468851277-12">]</span><span class="p" data-group-id="3468851277-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% Demonstrates type testing, selector, updating.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">birthday</span><span class="p" data-group-id="4357097441-13">(</span><span class="n">P</span><span class="p" data-group-id="4357097441-13">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="4357097441-14">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="4357097441-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4357097441-15">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4357097441-15">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">birthday</span><span class="p" data-group-id="3468851277-13">(</span><span class="n">P</span><span class="p" data-group-id="3468851277-13">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="3468851277-14">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="3468851277-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3468851277-15">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3468851277-15">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">register_two_hackers</span><span class="p" data-group-id="4357097441-16">(</span><span class="p" data-group-id="4357097441-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="n">Hacker1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="4357097441-17">(</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">29</span><span class="p" data-group-id="4357097441-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="n">OldHacker</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">birthday</span><span class="p" data-group-id="4357097441-18">(</span><span class="n">Hacker1</span><span class="p" data-group-id="4357097441-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">register_two_hackers</span><span class="p" data-group-id="3468851277-16">(</span><span class="p" data-group-id="3468851277-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="n">Hacker1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="3468851277-17">(</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">29</span><span class="p" data-group-id="3468851277-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="n">OldHacker</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">birthday</span><span class="p" data-group-id="3468851277-18">(</span><span class="n">Hacker1</span><span class="p" data-group-id="3468851277-18">)</span><span class="p">,</span><span class="w">
│ │ │ │     </span><span class="c1">% The central_register_server should have</span><span class="w">
│ │ │ │     </span><span class="c1">% an interface function for this.</span><span class="w">
│ │ │ │ -   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4357097441-19">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w"> </span><span class="n">Hacker1</span><span class="p" data-group-id="4357097441-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4357097441-20">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w">
│ │ │ │ -             </span><span class="n">OldHacker</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4357097441-21">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -                              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4357097441-22">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="4357097441-22">]</span><span class="p" data-group-id="4357097441-21">}</span><span class="p" data-group-id="4357097441-20">}</span><span class="p">.</span></code></pre>
│ │ │ │ +   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3468851277-19">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w"> </span><span class="n">Hacker1</span><span class="p" data-group-id="3468851277-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3468851277-20">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w">
│ │ │ │ +             </span><span class="n">OldHacker</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3468851277-21">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +                              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3468851277-22">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3468851277-22">]</span><span class="p" data-group-id="3468851277-21">}</span><span class="p" data-group-id="3468851277-20">}</span><span class="p">.</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/patterns.xhtml
│ │ │ │ @@ -33,16 +33,16 @@
│ │ │ │  succeeds, any unbound variables in the pattern become bound. If the matching
│ │ │ │  fails, an exception is raised.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** 1:1: variable &#39;X&#39; is unbound **</span><span class="gp unselectable">
│ │ │ │  2&gt; </span><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">2</span><span class="gp unselectable">
│ │ │ │  3&gt; </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="p" data-group-id="2050226777-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2050226777-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2050226777-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2050226777-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="p" data-group-id="4364461458-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4364461458-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4364461458-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="4364461458-2">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no match of right hand side value {1,2}</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="p" data-group-id="2050226777-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2050226777-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2050226777-4">{</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="2050226777-4">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2050226777-5">{</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2050226777-5">}</span><span class="gp unselectable">
│ │ │ │ +5&gt; </span><span class="p" data-group-id="4364461458-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4364461458-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4364461458-4">{</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="4364461458-4">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4364461458-5">{</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4364461458-5">}</span><span class="gp unselectable">
│ │ │ │  6&gt; </span><span class="n">Y</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/otp-patch-apply.xhtml
│ │ │ │ @@ -106,13 +106,13 @@
│ │ │ │    </a>
│ │ │ │    <span class="text">Sanity check</span>
│ │ │ │  </h2>
│ │ │ │  <p>The application dependencies can be checked using the Erlang shell.
│ │ │ │  Application dependencies are verified among installed applications by
│ │ │ │  <code class="inline">otp_patch_apply</code>, but these are not necessarily those actually loaded.
│ │ │ │  By calling <code class="inline">system_information:sanity_check()</code> one can validate
│ │ │ │ -dependencies among applications actually loaded.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">system_information</span><span class="p">:</span><span class="nf">sanity_check</span><span class="p" data-group-id="4509897693-1">(</span><span class="p" data-group-id="4509897693-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +dependencies among applications actually loaded.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">system_information</span><span class="p">:</span><span class="nf">sanity_check</span><span class="p" data-group-id="5384001409-1">(</span><span class="p" data-group-id="5384001409-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>Please take a look at the reference of <a href="../../../lib/runtime_tools/doc/html/system_information.html#sanity_check/0" title="">sanity_check()</a> for more
│ │ │ │  information.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/opaques.xhtml
│ │ │ │ @@ -27,24 +27,24 @@
│ │ │ │    <span class="text">Opaque Type Aliases</span>
│ │ │ │  </h2>
│ │ │ │  <p>The main use case for opacity in Erlang is to hide the implementation of a data
│ │ │ │  type, enabling evolving the API while minimizing the risk of breaking consumers.
│ │ │ │  The runtime does not check opacity. Dialyzer provides some opacity-checking, but
│ │ │ │  the rest is up to convention.</p><p>This document explains what Erlang opacity is (and the trade-offs involved) via
│ │ │ │  the example of the <a href="../../../lib/stdlib/doc/html/sets.html#t:set/0"><code class="inline">sets:set()</code></a> data type. This type <em>was</em>
│ │ │ │ -defined in the <code class="inline">sets</code> module like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="8643899754-1">(</span><span class="n">Element</span><span class="p" data-group-id="8643899754-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="8643899754-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="8643899754-3">(</span><span class="n">Element</span><span class="p" data-group-id="8643899754-3">)</span><span class="p" data-group-id="8643899754-2">}</span><span class="p">.</span></code></pre><p>OTP 24 changed the definition to the following in
│ │ │ │ -<a href="https://github.com/erlang/otp/commit/e66941e8d7c47b973dff94c0308ea85a6be1958e">this commit</a>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="2254182085-1">(</span><span class="n">Element</span><span class="p" data-group-id="2254182085-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="2254182085-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="2254182085-3">(</span><span class="n">Element</span><span class="p" data-group-id="2254182085-3">)</span><span class="p" data-group-id="2254182085-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="2254182085-4">#{</span><span class="n">Element</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VALUE</span><span class="p" data-group-id="2254182085-4">}</span><span class="p">.</span></code></pre><p>And this change was safer and more backwards-compatible than if the type had
│ │ │ │ +defined in the <code class="inline">sets</code> module like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="3888206148-1">(</span><span class="n">Element</span><span class="p" data-group-id="3888206148-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="3888206148-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="3888206148-3">(</span><span class="n">Element</span><span class="p" data-group-id="3888206148-3">)</span><span class="p" data-group-id="3888206148-2">}</span><span class="p">.</span></code></pre><p>OTP 24 changed the definition to the following in
│ │ │ │ +<a href="https://github.com/erlang/otp/commit/e66941e8d7c47b973dff94c0308ea85a6be1958e">this commit</a>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="4305964275-1">(</span><span class="n">Element</span><span class="p" data-group-id="4305964275-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="4305964275-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="4305964275-3">(</span><span class="n">Element</span><span class="p" data-group-id="4305964275-3">)</span><span class="p" data-group-id="4305964275-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="4305964275-4">#{</span><span class="n">Element</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VALUE</span><span class="p" data-group-id="4305964275-4">}</span><span class="p">.</span></code></pre><p>And this change was safer and more backwards-compatible than if the type had
│ │ │ │  been defined with <code class="inline">-type</code> instead of <code class="inline">-opaque</code>. Here is why: when a module
│ │ │ │  defines an <code class="inline">-opaque</code>, the contract is that only the defining module should rely
│ │ │ │  on the definition of the type: no other modules should rely on the definition.</p><p>This means that code that pattern-matched on <code class="inline">set</code> as a record/tuple technically
│ │ │ │  broke the contract, and opted in to being potentially broken when the definition
│ │ │ │  of <code class="inline">set()</code> changed. Before OTP 24, this code printed <code class="inline">ok</code>. In OTP 24 it may
│ │ │ │ -error:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="2522053452-1">(</span><span class="p" data-group-id="2522053452-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="n">Set</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_tuple</span><span class="p" data-group-id="2522053452-2">(</span><span class="n">Set</span><span class="p" data-group-id="2522053452-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2522053452-3">(</span><span class="s">&quot;ok&quot;</span><span class="p" data-group-id="2522053452-3">)</span><span class="w">
│ │ │ │ +error:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="1872907039-1">(</span><span class="p" data-group-id="1872907039-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="n">Set</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_tuple</span><span class="p" data-group-id="1872907039-2">(</span><span class="n">Set</span><span class="p" data-group-id="1872907039-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1872907039-3">(</span><span class="s">&quot;ok&quot;</span><span class="p" data-group-id="1872907039-3">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p><strong>When working with an opaque defined in another module, here are some
│ │ │ │  recommendations:</strong></p><ul><li>Don't examine the underlying type using pattern-matching, guards, or functions
│ │ │ │  that reveal the type, such as <a href="../../../lib/../erts/doc/html/erlang.html#tuple_size/1"><code class="inline">tuple_size/1</code></a> .</li><li>Instead, use functions provided by the module for working with the type. For
│ │ │ │  example, <code class="inline">sets</code> module provides <a href="../../../lib/stdlib/doc/html/sets.html#new/0"><code class="inline">sets:new/0</code></a>, <a href="../../../lib/stdlib/doc/html/sets.html#add_element/2"><code class="inline">sets:add_element/2</code></a>,
│ │ │ │  <a href="../../../lib/stdlib/doc/html/sets.html#is_element/2"><code class="inline">sets:is_element/2</code></a>, and so on.</li><li><p><a href="../../../lib/stdlib/doc/html/sets.html#t:set/1"><code class="inline">sets:set(a)</code></a> is a subtype of <code class="inline">sets:set(a | b)</code> and not the
│ │ │ │  other way around. Generally, you can rely on the property that <code class="inline">the_opaque(T)</code>
│ │ │ │  is a subtype of <code class="inline">the_opaque(U)</code> when T is a subtype of U.</p></li></ul><p><strong>When defining your own opaques, here are some recommendations:</strong></p><ul><li>Since consumers are expected to not rely on the definition of the opaque type,
│ │ │ ├── OEBPS/nif.xhtml
│ │ │ │ @@ -38,26 +38,26 @@
│ │ │ │    <span class="text">Erlang Program</span>
│ │ │ │  </h2>
│ │ │ │  <p>Even if all functions of a module are NIFs, an Erlang module is still needed for
│ │ │ │  two reasons:</p><ul><li>The NIF library must be explicitly loaded by Erlang code in the same module.</li><li>All NIFs of a module must have an Erlang implementation as well.</li></ul><p>Normally these are minimal stub implementations that throw an exception. But
│ │ │ │  they can also be used as fallback implementations for functions that do not have
│ │ │ │  native implementations on some architectures.</p><p>NIF libraries are loaded by calling <a href="../../../lib/../erts/doc/html/erlang.html#load_nif/2"><code class="inline">erlang:load_nif/2</code></a>, with the name of the
│ │ │ │  shared library as argument. The second argument can be any term that will be
│ │ │ │ -passed on to the library and used for initialization:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8967302827-1">(</span><span class="ss">complex6</span><span class="p" data-group-id="8967302827-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8967302827-2">(</span><span class="p" data-group-id="8967302827-3">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8967302827-3">]</span><span class="p" data-group-id="8967302827-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">nifs</span><span class="p" data-group-id="8967302827-4">(</span><span class="p" data-group-id="8967302827-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8967302827-5">]</span><span class="p" data-group-id="8967302827-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="8967302827-6">(</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8967302827-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="8967302827-7">(</span><span class="p" data-group-id="8967302827-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="8967302827-8">(</span><span class="s">&quot;./complex6_nif&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="8967302827-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="8967302827-9">(</span><span class="p">_</span><span class="n">X</span><span class="p" data-group-id="8967302827-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="8967302827-10">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="8967302827-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="8967302827-11">(</span><span class="p">_</span><span class="n">Y</span><span class="p" data-group-id="8967302827-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="8967302827-12">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="8967302827-12">)</span><span class="p">.</span></code></pre><p>Here, the directive <code class="inline">on_load</code> is used to get function <code class="inline">init</code> to be automatically
│ │ │ │ +passed on to the library and used for initialization:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5845875048-1">(</span><span class="ss">complex6</span><span class="p" data-group-id="5845875048-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5845875048-2">(</span><span class="p" data-group-id="5845875048-3">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5845875048-3">]</span><span class="p" data-group-id="5845875048-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">nifs</span><span class="p" data-group-id="5845875048-4">(</span><span class="p" data-group-id="5845875048-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5845875048-5">]</span><span class="p" data-group-id="5845875048-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="5845875048-6">(</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5845875048-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="5845875048-7">(</span><span class="p" data-group-id="5845875048-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="5845875048-8">(</span><span class="s">&quot;./complex6_nif&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="5845875048-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="5845875048-9">(</span><span class="p">_</span><span class="n">X</span><span class="p" data-group-id="5845875048-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="5845875048-10">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="5845875048-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="5845875048-11">(</span><span class="p">_</span><span class="n">Y</span><span class="p" data-group-id="5845875048-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="5845875048-12">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="5845875048-12">)</span><span class="p">.</span></code></pre><p>Here, the directive <code class="inline">on_load</code> is used to get function <code class="inline">init</code> to be automatically
│ │ │ │  called when the module is loaded. If <code class="inline">init</code> returns anything other than <code class="inline">ok</code>,
│ │ │ │  such when the loading of the NIF library fails in this example, the module is
│ │ │ │  unloaded and calls to functions within it, fail.</p><p>Loading the NIF library overrides the stub implementations and cause calls to
│ │ │ │  <code class="inline">foo</code> and <code class="inline">bar</code> to be dispatched to the NIF implementations instead.</p><h2 id="nif-library-code" class="section-heading">
│ │ │ │    <a href="#nif-library-code" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │ @@ -114,22 +114,22 @@
│ │ │ │    <a href="#running-the-example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Running the Example</span>
│ │ │ │  </h2>
│ │ │ │  <p><em>Step 1.</em> Compile the C code:</p><pre><code class="text">unix&gt; gcc -o complex6_nif.so -fpic -shared complex.c complex6_nif.c
│ │ │ │  windows&gt; cl -LD -MD -Fe complex6_nif.dll complex.c complex6_nif.c</code></pre><p><em>Step 2:</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="ss">erl</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="n">R13B04</span><span class="w"> </span><span class="p" data-group-id="9649990149-1">(</span><span class="ss">erts</span><span class="o">-</span><span class="mf">5.7</span><span class="p">.</span><span class="mi">5</span><span class="p" data-group-id="9649990149-1">)</span><span class="w"> </span><span class="p" data-group-id="9649990149-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="9649990149-2">]</span><span class="w"> </span><span class="p" data-group-id="9649990149-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="9649990149-3">]</span><span class="w"> </span><span class="p" data-group-id="9649990149-4">[</span><span class="nc">rq</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="9649990149-4">]</span><span class="w"> </span><span class="p" data-group-id="9649990149-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="9649990149-5">]</span><span class="w"> </span><span class="p" data-group-id="9649990149-6">[</span><span class="ss">kernel</span><span class="o">-</span><span class="nc">poll</span><span class="p">:</span><span class="ss">false</span><span class="p" data-group-id="9649990149-6">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="n">R13B04</span><span class="w"> </span><span class="p" data-group-id="1341926606-1">(</span><span class="ss">erts</span><span class="o">-</span><span class="mf">5.7</span><span class="p">.</span><span class="mi">5</span><span class="p" data-group-id="1341926606-1">)</span><span class="w"> </span><span class="p" data-group-id="1341926606-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="1341926606-2">]</span><span class="w"> </span><span class="p" data-group-id="1341926606-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="1341926606-3">]</span><span class="w"> </span><span class="p" data-group-id="1341926606-4">[</span><span class="nc">rq</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="1341926606-4">]</span><span class="w"> </span><span class="p" data-group-id="1341926606-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="1341926606-5">]</span><span class="w"> </span><span class="p" data-group-id="1341926606-6">[</span><span class="ss">kernel</span><span class="o">-</span><span class="nc">poll</span><span class="p">:</span><span class="ss">false</span><span class="p" data-group-id="1341926606-6">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">7.5</span><span class="w">  </span><span class="p" data-group-id="9649990149-7">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="9649990149-7">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="9649990149-8">(</span><span class="ss">complex6</span><span class="p" data-group-id="9649990149-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9649990149-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex6</span><span class="p" data-group-id="9649990149-9">}</span></code></pre><p><em>Step 3:</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="4746779408-1">(</span><span class="mi">3</span><span class="p" data-group-id="4746779408-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">7.5</span><span class="w">  </span><span class="p" data-group-id="1341926606-7">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="1341926606-7">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="1341926606-8">(</span><span class="ss">complex6</span><span class="p" data-group-id="1341926606-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1341926606-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex6</span><span class="p" data-group-id="1341926606-9">}</span></code></pre><p><em>Step 3:</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="1042953006-1">(</span><span class="mi">3</span><span class="p" data-group-id="1042953006-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="4746779408-2">(</span><span class="mi">5</span><span class="p" data-group-id="4746779408-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="1042953006-2">(</span><span class="mi">5</span><span class="p" data-group-id="1042953006-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="4746779408-3">(</span><span class="s">&quot;not an integer&quot;</span><span class="p" data-group-id="4746779408-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="1042953006-3">(</span><span class="s">&quot;not an integer&quot;</span><span class="p" data-group-id="1042953006-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: bad argument
│ │ │ │       in function  complex6:foo/1
│ │ │ │          called as comlpex6:foo(&quot;not an integer&quot;)</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/modules.xhtml
│ │ │ │ @@ -23,20 +23,20 @@
│ │ │ │  <h2 id="module-syntax" class="section-heading">
│ │ │ │    <a href="#module-syntax" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Module Syntax</span>
│ │ │ │  </h2>
│ │ │ │  <p>Erlang code is divided into <em>modules</em>. A module consists of a sequence of
│ │ │ │ -attributes and function declarations, each terminated by a period (<code class="inline">.</code>).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8472057323-1">(</span><span class="ss">m</span><span class="p" data-group-id="8472057323-1">)</span><span class="p">.</span><span class="w">          </span><span class="c1">% module attribute</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8472057323-2">(</span><span class="p" data-group-id="8472057323-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8472057323-3">]</span><span class="p" data-group-id="8472057323-2">)</span><span class="p">.</span><span class="w">   </span><span class="c1">% module attribute</span><span class="w">
│ │ │ │ +attributes and function declarations, each terminated by a period (<code class="inline">.</code>).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1877975412-1">(</span><span class="ss">m</span><span class="p" data-group-id="1877975412-1">)</span><span class="p">.</span><span class="w">          </span><span class="c1">% module attribute</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1877975412-2">(</span><span class="p" data-group-id="1877975412-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1877975412-3">]</span><span class="p" data-group-id="1877975412-2">)</span><span class="p">.</span><span class="w">   </span><span class="c1">% module attribute</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="8472057323-4">(</span><span class="n">N</span><span class="p" data-group-id="8472057323-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="o">&gt;</span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% beginning of function declaration</span><span class="w">
│ │ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="8472057323-5">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="8472057323-5">)</span><span class="p">;</span><span class="w">   </span><span class="c1">%  |</span><span class="w">
│ │ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="8472057323-6">(</span><span class="mi">0</span><span class="p" data-group-id="8472057323-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">           </span><span class="c1">%  |</span><span class="w">
│ │ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="1877975412-4">(</span><span class="n">N</span><span class="p" data-group-id="1877975412-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="o">&gt;</span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% beginning of function declaration</span><span class="w">
│ │ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="1877975412-5">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="1877975412-5">)</span><span class="p">;</span><span class="w">   </span><span class="c1">%  |</span><span class="w">
│ │ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="1877975412-6">(</span><span class="mi">0</span><span class="p" data-group-id="1877975412-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">           </span><span class="c1">%  |</span><span class="w">
│ │ │ │      </span><span class="mi">1</span><span class="p">.</span><span class="w">               </span><span class="c1">% end of function declaration</span></code></pre><p>For a description of function declarations, see
│ │ │ │  <a href="ref_man_functions.xhtml">Function Declaration Syntax</a>.</p><h2 id="module-attributes" class="section-heading">
│ │ │ │    <a href="#module-attributes" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Module Attributes</span>
│ │ │ │  </h2>
│ │ │ │ @@ -81,71 +81,71 @@
│ │ │ │  meaning.</p></section></li></ul><h3 id="behaviour-module-attribute" class="section-heading">
│ │ │ │    <a href="#behaviour-module-attribute" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Behaviour Module Attribute</span>
│ │ │ │  </h3>
│ │ │ │  <p>It is possible to specify that the module is the callback module for a
│ │ │ │ -<em>behaviour</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="6280729133-1">(</span><span class="n">Behaviour</span><span class="p" data-group-id="6280729133-1">)</span><span class="p">.</span></code></pre><p>The atom <code class="inline">Behaviour</code> gives the name of the behaviour, which can be a
│ │ │ │ +<em>behaviour</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5779859104-1">(</span><span class="n">Behaviour</span><span class="p" data-group-id="5779859104-1">)</span><span class="p">.</span></code></pre><p>The atom <code class="inline">Behaviour</code> gives the name of the behaviour, which can be a
│ │ │ │  user-defined behaviour or one of the following OTP standard behaviours:</p><ul><li><code class="inline">gen_server</code></li><li><code class="inline">gen_statem</code></li><li><code class="inline">gen_event</code></li><li><code class="inline">supervisor</code></li></ul><p>The spelling <code class="inline">behavior</code> is also accepted.</p><p>The callback functions of the module can be specified either directly by the
│ │ │ │ -exported function <code class="inline">behaviour_info/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="4154234026-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="4154234026-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Callbacks</span><span class="p">.</span></code></pre><p>or by a <code class="inline">-callback</code> attribute for each callback function:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5014936048-1">(</span><span class="n">Arguments</span><span class="p" data-group-id="5014936048-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="p">.</span></code></pre><p>Here, <code class="inline">Arguments</code> is a list of zero or more arguments. The <code class="inline">-callback</code> attribute
│ │ │ │ +exported function <code class="inline">behaviour_info/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="0247106706-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="0247106706-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Callbacks</span><span class="p">.</span></code></pre><p>or by a <code class="inline">-callback</code> attribute for each callback function:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3815268806-1">(</span><span class="n">Arguments</span><span class="p" data-group-id="3815268806-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="p">.</span></code></pre><p>Here, <code class="inline">Arguments</code> is a list of zero or more arguments. The <code class="inline">-callback</code> attribute
│ │ │ │  is to be preferred since the extra type information can be used by tools to
│ │ │ │  produce documentation or find discrepancies.</p><p>Read more about behaviours and callback modules in
│ │ │ │  <a href="../../../lib/../system/doc/html/spec_proc.xhtml#behaviours">OTP Design Principles</a>.</p><h3 id="record-definitions" class="section-heading">
│ │ │ │    <a href="#record-definitions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Record Definitions</span>
│ │ │ │  </h3>
│ │ │ │ -<p>The same syntax as for module attributes is used for record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3171390883-1">(</span><span class="n">Record</span><span class="p">,</span><span class="w"> </span><span class="n">Fields</span><span class="p" data-group-id="3171390883-1">)</span><span class="p">.</span></code></pre><p>Record definitions are allowed anywhere in a module, also among the function
│ │ │ │ +<p>The same syntax as for module attributes is used for record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3490354795-1">(</span><span class="n">Record</span><span class="p">,</span><span class="w"> </span><span class="n">Fields</span><span class="p" data-group-id="3490354795-1">)</span><span class="p">.</span></code></pre><p>Record definitions are allowed anywhere in a module, also among the function
│ │ │ │  declarations. Read more in <a href="ref_man_records.xhtml">Records</a>.</p><h3 id="preprocessor" class="section-heading">
│ │ │ │    <a href="#preprocessor" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Preprocessor</span>
│ │ │ │  </h3>
│ │ │ │  <p>The same syntax as for module attributes is used by the preprocessor, which
│ │ │ │ -supports file inclusion, macros, and conditional compilation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="4216608454-1">(</span><span class="s">&quot;SomeFile.hrl&quot;</span><span class="p" data-group-id="4216608454-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="4216608454-2">(</span><span class="n">Macro</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="4216608454-2">)</span><span class="p">.</span></code></pre><p>Read more in <a href="macros.xhtml">Preprocessor</a>.</p><h3 id="setting-file-and-line" class="section-heading">
│ │ │ │ +supports file inclusion, macros, and conditional compilation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="5764776367-1">(</span><span class="s">&quot;SomeFile.hrl&quot;</span><span class="p" data-group-id="5764776367-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5764776367-2">(</span><span class="n">Macro</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="5764776367-2">)</span><span class="p">.</span></code></pre><p>Read more in <a href="macros.xhtml">Preprocessor</a>.</p><h3 id="setting-file-and-line" class="section-heading">
│ │ │ │    <a href="#setting-file-and-line" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Setting File and Line</span>
│ │ │ │  </h3>
│ │ │ │  <p>The same syntax as for module attributes is used for changing the pre-defined
│ │ │ │ -macros <code class="inline">?FILE</code> and <code class="inline">?LINE</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">file</span><span class="p" data-group-id="7615514217-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">Line</span><span class="p" data-group-id="7615514217-1">)</span><span class="p">.</span></code></pre><p>This attribute is used by tools, such as Yecc, to inform the compiler that the
│ │ │ │ +macros <code class="inline">?FILE</code> and <code class="inline">?LINE</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">file</span><span class="p" data-group-id="4774052085-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">Line</span><span class="p" data-group-id="4774052085-1">)</span><span class="p">.</span></code></pre><p>This attribute is used by tools, such as Yecc, to inform the compiler that the
│ │ │ │  source program is generated by another tool. It also indicates the
│ │ │ │  correspondence of source files to lines of the original user-written file, from
│ │ │ │  which the source program is produced.</p><h3 id="types-and-function-specifications" class="section-heading">
│ │ │ │    <a href="#types-and-function-specifications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Types and function specifications</span>
│ │ │ │  </h3>
│ │ │ │  <p>A similar syntax as for module attributes is used for specifying types and
│ │ │ │ -function specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_type</span><span class="p" data-group-id="5950921864-1">(</span><span class="p" data-group-id="5950921864-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="5950921864-2">(</span><span class="p" data-group-id="5950921864-2">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="5950921864-3">(</span><span class="p" data-group-id="5950921864-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">my_function</span><span class="p" data-group-id="5950921864-4">(</span><span class="nf">integer</span><span class="p" data-group-id="5950921864-5">(</span><span class="p" data-group-id="5950921864-5">)</span><span class="p" data-group-id="5950921864-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="5950921864-6">(</span><span class="p" data-group-id="5950921864-6">)</span><span class="p">.</span></code></pre><p>Read more in <a href="typespec.xhtml">Types and Function specifications</a>.</p><p>The description is based on
│ │ │ │ +function specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_type</span><span class="p" data-group-id="1404558375-1">(</span><span class="p" data-group-id="1404558375-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="1404558375-2">(</span><span class="p" data-group-id="1404558375-2">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="1404558375-3">(</span><span class="p" data-group-id="1404558375-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">my_function</span><span class="p" data-group-id="1404558375-4">(</span><span class="nf">integer</span><span class="p" data-group-id="1404558375-5">(</span><span class="p" data-group-id="1404558375-5">)</span><span class="p" data-group-id="1404558375-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="1404558375-6">(</span><span class="p" data-group-id="1404558375-6">)</span><span class="p">.</span></code></pre><p>Read more in <a href="typespec.xhtml">Types and Function specifications</a>.</p><p>The description is based on
│ │ │ │  <a href="http://www.erlang.org/eeps/eep-0008.html">EEP8 - Types and function specifications</a>,
│ │ │ │  which is not to be further updated.</p><h3 id="documentation-attributes" class="section-heading">
│ │ │ │    <a href="#documentation-attributes" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Documentation attributes</span>
│ │ │ │  </h3>
│ │ │ │  <p>The module attribute <code class="inline">-doc(Documentation)</code> is used to provide user documentation
│ │ │ │ -for a function/type/callback:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="8987983745-1">(</span><span class="s">&quot;Example documentation&quot;</span><span class="p" data-group-id="8987983745-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">example</span><span class="p" data-group-id="8987983745-2">(</span><span class="p" data-group-id="8987983745-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The attribute should be placed just before the entity it documents.The
│ │ │ │ +for a function/type/callback:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="2680217190-1">(</span><span class="s">&quot;Example documentation&quot;</span><span class="p" data-group-id="2680217190-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">example</span><span class="p" data-group-id="2680217190-2">(</span><span class="p" data-group-id="2680217190-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The attribute should be placed just before the entity it documents.The
│ │ │ │  parenthesis are optional around <code class="inline">Documentation</code>. The allowed values for
│ │ │ │  <code class="inline">Documentation</code> are:</p><ul><li><p><strong><a href="data_types.xhtml#string">literal string</a> or
│ │ │ │  <a href="expressions.xhtml#unicode-segments">utf-8 encoded binary string</a></strong> - The string
│ │ │ │  documenting the entity. Any literal string is allowed, so both
│ │ │ │  <a href="data_types.xhtml#tqstring">triple quoted strings</a> and
│ │ │ │  <a href="data_types.xhtml#sigil">sigils</a> that translate to literal strings can be used.
│ │ │ │ -The following examples are equivalent:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="5597255056-1">(</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="p" data-group-id="5597255056-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="5597255056-2">(</span><span class="p" data-group-id="5597255056-3">&lt;&lt;</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="5597255056-3">&gt;&gt;</span><span class="p" data-group-id="5597255056-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +The following examples are equivalent:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="2409761500-1">(</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="p" data-group-id="2409761500-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="2409761500-2">(</span><span class="p" data-group-id="2409761500-3">&lt;&lt;</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="2409761500-3">&gt;&gt;</span><span class="p" data-group-id="2409761500-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">~S/Example &quot;docs&quot;/</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="s">&quot;
│ │ │ │     Example &quot;</span><span class="ss">docs</span><span class="s">&quot;
│ │ │ │     &quot;</span><span class="s">&quot;&quot;</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">~B|Example &quot;docs&quot;|</span><span class="p">.</span></code></pre><p>For clarity it is recommended to use either normal <code class="inline">&quot;strings&quot;</code> or triple
│ │ │ │  quoted strings for documentation attributes.</p></li><li><p><strong><code class="inline">{file,</code> <a href="../../../lib/kernel/doc/html/file.html#t:name/0"><code class="inline">file:name/0</code></a> <code class="inline">}</code></strong> - Read the contents of filename and use
│ │ │ │  that as the documentation string.</p></li><li><p><strong><code class="inline">false</code></strong> - Set the current entity as hidden, that is, it should not be
│ │ │ │ @@ -158,15 +158,15 @@
│ │ │ │    <a href="#the-feature-directive" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">The feature directive</span>
│ │ │ │  </h2>
│ │ │ │  <p>While not a module attribute, but rather a directive (since it might affect
│ │ │ │  syntax), there is the <code class="inline">-feature(..)</code> directive used for enabling and disabling
│ │ │ │ -<a href="../../../lib/../system/doc/html/features.xhtml#features">features</a>.</p><p>The syntax is similar to that of an attribute, but has two arguments:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">feature</span><span class="p" data-group-id="4607743023-1">(</span><span class="n">FeatureName</span><span class="p">,</span><span class="w"> </span><span class="ss">enable</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">disable</span><span class="p" data-group-id="4607743023-1">)</span><span class="p">.</span></code></pre><p>Note that the <a href="macros.xhtml#feature-directive">feature directive</a> can only appear
│ │ │ │ +<a href="../../../lib/../system/doc/html/features.xhtml#features">features</a>.</p><p>The syntax is similar to that of an attribute, but has two arguments:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">feature</span><span class="p" data-group-id="9318699821-1">(</span><span class="n">FeatureName</span><span class="p">,</span><span class="w"> </span><span class="ss">enable</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">disable</span><span class="p" data-group-id="9318699821-1">)</span><span class="p">.</span></code></pre><p>Note that the <a href="macros.xhtml#feature-directive">feature directive</a> can only appear
│ │ │ │  in a prefix of the module.</p><h2 id="comments" class="section-heading">
│ │ │ │    <a href="#comments" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Comments</span>
│ │ │ │  </h2>
│ │ │ │  <p>Comments can be placed anywhere in a module except within strings and
│ │ │ ├── OEBPS/maps.xhtml
│ │ │ │ @@ -53,16 +53,16 @@
│ │ │ │  single function that constructs the map using the map syntax and always use
│ │ │ │  it.</p></li><li><p>Always update the map using the <code class="inline">:=</code> operator (that is, requiring that an
│ │ │ │  element with that key already exists). The <code class="inline">:=</code> operator is slightly more
│ │ │ │  efficient, and it helps catching mispellings of keys.</p></li><li><p>Whenever possible, match multiple map elements at once.</p></li><li><p>Whenever possible, update multiple map elements at once.</p></li><li><p>Avoid default values and the <a href="../../../lib/stdlib/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> function. If there are default
│ │ │ │  values, sharing of keys between different instances of the map will be less
│ │ │ │  effective, and it is not possible to match multiple elements having default
│ │ │ │  values in one go.</p></li><li><p>To avoid having to deal with a map that may lack some keys, <a href="../../../lib/stdlib/doc/html/maps.html#merge/2"><code class="inline">maps:merge/2</code></a> can
│ │ │ │ -efficiently add multiple default values. For example:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6556171432-1">#{</span><span class="ss">shoe_size</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="ss">editor</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">emacs</span><span class="p" data-group-id="6556171432-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="6556171432-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="6556171432-2">)</span></code></pre></li></ul><h2 id="using-maps-as-dictionaries" class="section-heading">
│ │ │ │ +efficiently add multiple default values. For example:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9689434730-1">#{</span><span class="ss">shoe_size</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="ss">editor</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">emacs</span><span class="p" data-group-id="9689434730-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="9689434730-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="9689434730-2">)</span></code></pre></li></ul><h2 id="using-maps-as-dictionaries" class="section-heading">
│ │ │ │    <a href="#using-maps-as-dictionaries" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Using Maps as Dictionaries</span>
│ │ │ │  </h2>
│ │ │ │  <p>Using a map as a dictionary implies the following usage pattern:</p><ul><li>Keys are usually variables not known at compile-time.</li><li>There can be any number of elements in the map.</li><li>Usually, no more than one element is looked up or updated at once.</li></ul><p>Given that usage pattern, the difference in performance between using the map
│ │ │ │  syntax and the maps module is usually small. Therefore, which one to use is
│ │ │ │ @@ -72,18 +72,18 @@
│ │ │ │  choice.</li></ul><h2 id="using-maps-as-sets" class="section-heading">
│ │ │ │    <a href="#using-maps-as-sets" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Using Maps as Sets</span>
│ │ │ │  </h2>
│ │ │ │  <p>Starting in OTP 24, the <a href="../../../lib/stdlib/doc/html/sets.html"><code class="inline">sets</code></a> module has an option to represent sets as maps.
│ │ │ │ -Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="8057979856-1">(</span><span class="p" data-group-id="8057979856-2">[</span><span class="p" data-group-id="8057979856-3">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8057979856-3">}</span><span class="p" data-group-id="8057979856-2">]</span><span class="p" data-group-id="8057979856-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8057979856-4">#{</span><span class="p" data-group-id="8057979856-4">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">from_list</span><span class="p" data-group-id="8057979856-5">(</span><span class="p" data-group-id="8057979856-6">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="8057979856-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8057979856-7">[</span><span class="p" data-group-id="8057979856-8">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8057979856-8">}</span><span class="p" data-group-id="8057979856-7">]</span><span class="p" data-group-id="8057979856-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8057979856-9">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8057979856-10">[</span><span class="p" data-group-id="8057979856-10">]</span><span class="p">,</span><span class="ss">y</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8057979856-11">[</span><span class="p" data-group-id="8057979856-11">]</span><span class="p">,</span><span class="ss">z</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8057979856-12">[</span><span class="p" data-group-id="8057979856-12">]</span><span class="p" data-group-id="8057979856-9">}</span></code></pre><p><code class="inline">sets</code> backed by maps is generally the most efficient set representation, with a
│ │ │ │ +Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="4667742786-1">(</span><span class="p" data-group-id="4667742786-2">[</span><span class="p" data-group-id="4667742786-3">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4667742786-3">}</span><span class="p" data-group-id="4667742786-2">]</span><span class="p" data-group-id="4667742786-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4667742786-4">#{</span><span class="p" data-group-id="4667742786-4">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">from_list</span><span class="p" data-group-id="4667742786-5">(</span><span class="p" data-group-id="4667742786-6">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="4667742786-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4667742786-7">[</span><span class="p" data-group-id="4667742786-8">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4667742786-8">}</span><span class="p" data-group-id="4667742786-7">]</span><span class="p" data-group-id="4667742786-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4667742786-9">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4667742786-10">[</span><span class="p" data-group-id="4667742786-10">]</span><span class="p">,</span><span class="ss">y</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4667742786-11">[</span><span class="p" data-group-id="4667742786-11">]</span><span class="p">,</span><span class="ss">z</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4667742786-12">[</span><span class="p" data-group-id="4667742786-12">]</span><span class="p" data-group-id="4667742786-9">}</span></code></pre><p><code class="inline">sets</code> backed by maps is generally the most efficient set representation, with a
│ │ │ │  few possible exceptions:</p><ul><li><a href="../../../lib/stdlib/doc/html/ordsets.html#intersection/2"><code class="inline">ordsets:intersection/2</code></a> can be more efficient than <a href="../../../lib/stdlib/doc/html/sets.html#intersection/2"><code class="inline">sets:intersection/2</code></a>. If
│ │ │ │  the intersection operation is frequently used and operations that operate on a
│ │ │ │  single element in a set (such as <code class="inline">is_element/2</code>) are avoided, <a href="../../../lib/stdlib/doc/html/ordsets.html"><code class="inline">ordsets</code></a> can
│ │ │ │  be a better choice than <a href="../../../lib/stdlib/doc/html/sets.html"><code class="inline">sets</code></a>.</li><li>If the intersection operation is frequently used and operations that operate
│ │ │ │  on a single element in a set (such as <code class="inline">is_element/2</code>) must also be efficient,
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gb_sets.html"><code class="inline">gb_sets</code></a> can potentially be a better choice than <a href="../../../lib/stdlib/doc/html/sets.html"><code class="inline">sets</code></a>.</li><li>If the elements of the set are integers in a fairly compact range, the set can
│ │ │ │  be represented as an integer where each bit represents an element in the set.
│ │ │ │ @@ -108,18 +108,18 @@
│ │ │ │  for the runtime system).</p></li><li><p><strong>N</strong> - The number of elements in the map.</p></li><li><p><strong>Keys</strong> - A tuple with keys of the map: <code class="inline">{Key1,...,KeyN}</code>. The keys are
│ │ │ │  sorted.</p></li><li><p><strong>Value1</strong> - The value corresponding to the first key in the key tuple.</p></li><li><p><strong>ValueN</strong> - The value corresponding to the last key in the key tuple.</p></li></ul><p>As an example, let us look at how the map <code class="inline">#{a =&gt; foo, z =&gt; bar}</code> is
│ │ │ │  represented:</p><table><thead><tr><th style="text-align: center;">0</th><th style="text-align: left;">1</th><th style="text-align: center;">2</th><th style="text-align: center;">3</th><th style="text-align: left;">4</th></tr></thead><tbody><tr><td style="text-align: center;"><strong>FLATMAP</strong></td><td style="text-align: left;"><em>2</em></td><td style="text-align: center;"><code class="inline">{a,z}</code></td><td style="text-align: center;"><code class="inline">foo</code></td><td style="text-align: left;"><code class="inline">bar</code></td></tr></tbody></table><p><em>Table: #{a =&gt; foo, z =&gt; bar}</em></p><p>Let us update the map: <code class="inline">M#{q =&gt; baz}</code>. The map now looks like this:</p><table><thead><tr><th style="text-align: center;">0</th><th style="text-align: left;">1</th><th style="text-align: center;">2</th><th style="text-align: center;">3</th><th style="text-align: center;">4</th><th style="text-align: center;">5</th></tr></thead><tbody><tr><td style="text-align: center;"><strong>FLATMAP</strong></td><td style="text-align: left;"><em>3</em></td><td style="text-align: center;"><code class="inline">{a,q,z}</code></td><td style="text-align: center;"><code class="inline">foo</code></td><td style="text-align: center;"><code class="inline">baz</code></td><td style="text-align: center;"><code class="inline">bar</code></td></tr></tbody></table><p><em>Table: #{a =&gt; foo, q =&gt; baz, z =&gt; bar}</em></p><p>Finally, change the value of one element: <code class="inline">M#{z := bird}</code>. The map now looks
│ │ │ │  like this:</p><table><thead><tr><th style="text-align: center;">0</th><th style="text-align: left;">1</th><th style="text-align: center;">2</th><th style="text-align: center;">3</th><th style="text-align: center;">4</th><th style="text-align: center;">5</th></tr></thead><tbody><tr><td style="text-align: center;"><strong>FLATMAP</strong></td><td style="text-align: left;"><em>3</em></td><td style="text-align: center;"><code class="inline">{a,q,z}</code></td><td style="text-align: center;"><code class="inline">foo</code></td><td style="text-align: center;"><code class="inline">baz</code></td><td style="text-align: center;"><code class="inline">bird</code></td></tr></tbody></table><p><em>Table: #{a =&gt; foo, q =&gt; baz, z =&gt; bird}</em></p><p>When the value for an existing key is updated, the key tuple is not updated,
│ │ │ │  allowing the key tuple to be shared with other instances of the map that have
│ │ │ │  the same keys. In fact, the key tuple can be shared between all maps with the
│ │ │ │  same keys with some care. To arrange that, define a function that returns a map.
│ │ │ │ -For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="5242059870-1">(</span><span class="p" data-group-id="5242059870-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5242059870-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p" data-group-id="5242059870-2">}</span><span class="p">.</span></code></pre><p>Defined like this, the key tuple <code class="inline">{a,b,c}</code> will be a global literal. To ensure
│ │ │ │ +For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="2109765572-1">(</span><span class="p" data-group-id="2109765572-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2109765572-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p" data-group-id="2109765572-2">}</span><span class="p">.</span></code></pre><p>Defined like this, the key tuple <code class="inline">{a,b,c}</code> will be a global literal. To ensure
│ │ │ │  that the key tuple is shared when creating an instance of the map, always call
│ │ │ │ -<code class="inline">new()</code> and modify the returned map:</p><pre><code class="makeup erlang" translate="no"><span class="w">    </span><span class="p" data-group-id="7462137345-1">(</span><span class="n">SOME_MODULE</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="7462137345-2">(</span><span class="p" data-group-id="7462137345-2">)</span><span class="p" data-group-id="7462137345-1">)</span><span class="p" data-group-id="7462137345-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="7462137345-3">}</span><span class="p">.</span></code></pre><p>Using the map syntax with small maps is particularly efficient. As long as the
│ │ │ │ +<code class="inline">new()</code> and modify the returned map:</p><pre><code class="makeup erlang" translate="no"><span class="w">    </span><span class="p" data-group-id="7875431552-1">(</span><span class="n">SOME_MODULE</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="7875431552-2">(</span><span class="p" data-group-id="7875431552-2">)</span><span class="p" data-group-id="7875431552-1">)</span><span class="p" data-group-id="7875431552-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="7875431552-3">}</span><span class="p">.</span></code></pre><p>Using the map syntax with small maps is particularly efficient. As long as the
│ │ │ │  keys are known at compile-time, the map is updated in one go, making the time to
│ │ │ │  update a map essentially constant regardless of the number of keys updated. The
│ │ │ │  same goes for matching. (When the keys are variables, one or more of the keys
│ │ │ │  could be identical, so the operations need to be performed sequentially from
│ │ │ │  left to right.)</p><p>The memory size for a small map is the size of all keys and values plus 5 words.
│ │ │ │  See <a href="memory.xhtml">Memory</a> for more information about memory sizes.</p><h3 id="how-large-maps-are-implemented" class="section-heading">
│ │ │ │    <a href="#how-large-maps-are-implemented" class="hover-link">
│ │ │ │ @@ -146,21 +146,21 @@
│ │ │ │    <a href="#using-the-map-syntax" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Using the Map Syntax</span>
│ │ │ │  </h2>
│ │ │ │  <p>Using the map syntax is usually slightly more efficient than using the
│ │ │ │  corresponding function in the <a href="../../../lib/stdlib/doc/html/maps.html"><code class="inline">maps</code></a> module.</p><p>The gain in efficiency for the map syntax is more noticeable for the following
│ │ │ │ -operations that can only be achieved using the map syntax:</p><ul><li>Matching multiple literal keys</li><li>Updating multiple literal keys</li><li>Adding multiple literal keys to a map</li></ul><p>For example:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="1232772726-1">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="ss">z</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="1232772726-1">}</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="0586585689-1">(</span><span class="ss">x</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="0586585689-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="0586585689-2">(</span><span class="ss">y</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="0586585689-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="0586585689-3">(</span><span class="ss">z</span><span class="p">,</span><span class="w"> </span><span class="n">Z</span><span class="p">,</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="0586585689-3">)</span></code></pre><p>If the map is a small map, the first example runs roughly three times as fast.</p><p>Note that for variable keys, the elements are updated sequentially from left to
│ │ │ │ -right. For example, given the following update with variable keys:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="3440206805-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="3440206805-1">}</span></code></pre><p>the compiler rewrites it like this to ensure that the updates are applied from
│ │ │ │ -left to right:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="7058866207-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7058866207-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="7058866207-2">#{</span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7058866207-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="7058866207-3">#{</span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="7058866207-3">}</span></code></pre><p>If a key is known to exist in a map, using the <code class="inline">:=</code> operator is slightly more
│ │ │ │ +operations that can only be achieved using the map syntax:</p><ul><li>Matching multiple literal keys</li><li>Updating multiple literal keys</li><li>Adding multiple literal keys to a map</li></ul><p>For example:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="4018050237-1">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="ss">z</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="4018050237-1">}</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="8026760828-1">(</span><span class="ss">x</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="8026760828-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="8026760828-2">(</span><span class="ss">y</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="8026760828-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="8026760828-3">(</span><span class="ss">z</span><span class="p">,</span><span class="w"> </span><span class="n">Z</span><span class="p">,</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="8026760828-3">)</span></code></pre><p>If the map is a small map, the first example runs roughly three times as fast.</p><p>Note that for variable keys, the elements are updated sequentially from left to
│ │ │ │ +right. For example, given the following update with variable keys:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="8611781300-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="8611781300-1">}</span></code></pre><p>the compiler rewrites it like this to ensure that the updates are applied from
│ │ │ │ +left to right:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="6010881123-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6010881123-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="6010881123-2">#{</span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6010881123-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="6010881123-3">#{</span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="6010881123-3">}</span></code></pre><p>If a key is known to exist in a map, using the <code class="inline">:=</code> operator is slightly more
│ │ │ │  efficient than using the <code class="inline">=&gt;</code> operator for a small map.</p><h2 id="using-the-functions-in-the-maps-module" class="section-heading">
│ │ │ │    <a href="#using-the-functions-in-the-maps-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Using the Functions in the maps Module</span>
│ │ │ │  </h2>
│ │ │ │  <p>Here follows some notes about most of the functions in the <code class="inline">maps</code> module. For
│ │ │ │ @@ -211,23 +211,23 @@
│ │ │ │    <a href="#maps-get-3" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">maps:get/3</span>
│ │ │ │  </h3>
│ │ │ │  <p>As an optimization, the compiler will rewrite a call to <a href="../../../lib/stdlib/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> to Erlang
│ │ │ │  code similar to the following:</p><pre><code class="makeup erlang" translate="no"><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="n">Map</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="3975021317-1">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="3975021317-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="p">;</span><span class="w">
│ │ │ │ -             </span><span class="p" data-group-id="3975021317-2">#{</span><span class="p" data-group-id="3975021317-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Default</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="7323429315-1">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="7323429315-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="p">;</span><span class="w">
│ │ │ │ +             </span><span class="p" data-group-id="7323429315-2">#{</span><span class="p" data-group-id="7323429315-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Default</span><span class="w">
│ │ │ │           </span><span class="k">end</span></code></pre><p>This is reasonably efficient, but if a small map is used as an alternative to
│ │ │ │  using a record it is often better not to rely on default values as it prevents
│ │ │ │  sharing of keys, which may in the end use more memory than what you save from
│ │ │ │  not storing default values in the map.</p><p>If default values are nevertheless required, instead of calling <a href="../../../lib/stdlib/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a>
│ │ │ │  multiple times, consider putting the default values in a map and merging that
│ │ │ │ -map with the other map:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4735775733-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">KeyN</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueN</span><span class="p" data-group-id="4735775733-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="4735775733-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="4735775733-2">)</span></code></pre><p>This helps share keys between the default map and the one you applied defaults
│ │ │ │ +map with the other map:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3773365429-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">KeyN</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueN</span><span class="p" data-group-id="3773365429-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="3773365429-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="3773365429-2">)</span></code></pre><p>This helps share keys between the default map and the one you applied defaults
│ │ │ │  to, as long as the default map contains <em>all</em> the keys that will ever be used
│ │ │ │  and not just the ones with default values. Whether this is faster than calling
│ │ │ │  <a href="../../../lib/stdlib/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> multiple times depends on the size of the map and the number of
│ │ │ │  default values.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before OTP 26.0 <a href="../../../lib/stdlib/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> was implemented by calling the function instead
│ │ │ │  of rewriting it as an Erlang expression. It is now slightly faster but can no
│ │ │ │  longer be traced.</p></section><h3 id="maps-intersect-2-maps-intersect_with-3" class="section-heading">
│ │ │ │    <a href="#maps-intersect-2-maps-intersect_with-3" class="hover-link">
│ │ │ ├── OEBPS/macros.xhtml
│ │ │ │ @@ -22,56 +22,56 @@
│ │ │ │      </h1>
│ │ │ │  <h2 id="file-inclusion" class="section-heading">
│ │ │ │    <a href="#file-inclusion" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">File Inclusion</span>
│ │ │ │  </h2>
│ │ │ │ -<p>A file can be included as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="3791035304-1">(</span><span class="n">File</span><span class="p" data-group-id="3791035304-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="3791035304-2">(</span><span class="n">File</span><span class="p" data-group-id="3791035304-2">)</span><span class="p">.</span></code></pre><p><code class="inline">File</code>, a string, is to point out a file. The contents of this file are included
│ │ │ │ +<p>A file can be included as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="2163737915-1">(</span><span class="n">File</span><span class="p" data-group-id="2163737915-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="2163737915-2">(</span><span class="n">File</span><span class="p" data-group-id="2163737915-2">)</span><span class="p">.</span></code></pre><p><code class="inline">File</code>, a string, is to point out a file. The contents of this file are included
│ │ │ │  as is, at the position of the directive.</p><p>Include files are typically used for record and macro definitions that are
│ │ │ │  shared by several modules. It is recommended to use the file name extension
│ │ │ │  <code class="inline">.hrl</code> for include files.</p><p><code class="inline">File</code> can start with a path component <code class="inline">$VAR</code>, for some string <code class="inline">VAR</code>. If that is
│ │ │ │  the case, the value of the environment variable <code class="inline">VAR</code> as returned by
│ │ │ │  <code class="inline">os:getenv(VAR)</code> is substituted for <code class="inline">$VAR</code>. If <code class="inline">os:getenv(VAR)</code> returns <code class="inline">false</code>,
│ │ │ │  <code class="inline">$VAR</code> is left as is.</p><p>If the filename <code class="inline">File</code> is absolute (possibly after variable substitution), the
│ │ │ │  include file with that name is included. Otherwise, the specified file is
│ │ │ │  searched for in the following directories, and in this order:</p><ol><li>The current working directory</li><li>The directory where the module is being compiled</li><li>The directories given by the <code class="inline">include</code> option</li></ol><p>For details, see <a href="../../../lib/../erts/doc/html/erlc_cmd.xhtml">erlc</a> in ERTS and
│ │ │ │ -<a href="../../../lib/compiler/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8246936717-1">(</span><span class="s">&quot;my_records.hrl&quot;</span><span class="p" data-group-id="8246936717-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8246936717-2">(</span><span class="s">&quot;incdir/my_records.hrl&quot;</span><span class="p" data-group-id="8246936717-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8246936717-3">(</span><span class="s">&quot;/home/user/proj/my_records.hrl&quot;</span><span class="p" data-group-id="8246936717-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8246936717-4">(</span><span class="s">&quot;$PROJ_ROOT/my_records.hrl&quot;</span><span class="p" data-group-id="8246936717-4">)</span><span class="p">.</span></code></pre><p><code class="inline">include_lib</code> is similar to <code class="inline">include</code>, but is not to point out an absolute file.
│ │ │ │ +<a href="../../../lib/compiler/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8843306051-1">(</span><span class="s">&quot;my_records.hrl&quot;</span><span class="p" data-group-id="8843306051-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8843306051-2">(</span><span class="s">&quot;incdir/my_records.hrl&quot;</span><span class="p" data-group-id="8843306051-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8843306051-3">(</span><span class="s">&quot;/home/user/proj/my_records.hrl&quot;</span><span class="p" data-group-id="8843306051-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8843306051-4">(</span><span class="s">&quot;$PROJ_ROOT/my_records.hrl&quot;</span><span class="p" data-group-id="8843306051-4">)</span><span class="p">.</span></code></pre><p><code class="inline">include_lib</code> is similar to <code class="inline">include</code>, but is not to point out an absolute file.
│ │ │ │  Instead, the first path component (possibly after variable substitution) is
│ │ │ │ -assumed to be the name of an application.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="9807601149-1">(</span><span class="s">&quot;kernel/include/file.hrl&quot;</span><span class="p" data-group-id="9807601149-1">)</span><span class="p">.</span></code></pre><p>The code server uses <code class="inline">code:lib_dir(kernel)</code> to find the directory of the current
│ │ │ │ +assumed to be the name of an application.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="7804215750-1">(</span><span class="s">&quot;kernel/include/file.hrl&quot;</span><span class="p" data-group-id="7804215750-1">)</span><span class="p">.</span></code></pre><p>The code server uses <code class="inline">code:lib_dir(kernel)</code> to find the directory of the current
│ │ │ │  (latest) version of Kernel, and then the subdirectory <code class="inline">include</code> is searched for
│ │ │ │  the file <code class="inline">file.hrl</code>.</p><h2 id="defining-and-using-macros" class="section-heading">
│ │ │ │    <a href="#defining-and-using-macros" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Defining and Using Macros</span>
│ │ │ │  </h2>
│ │ │ │ -<p>A macro is defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3343995248-1">(</span><span class="n">Const</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="3343995248-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3343995248-2">(</span><span class="n">Func</span><span class="p" data-group-id="3343995248-3">(</span><span class="n">Var1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">VarN</span><span class="p" data-group-id="3343995248-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="3343995248-2">)</span><span class="p">.</span></code></pre><p>A macro definition can be placed anywhere among the attributes and function
│ │ │ │ +<p>A macro is defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5323036112-1">(</span><span class="n">Const</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="5323036112-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5323036112-2">(</span><span class="n">Func</span><span class="p" data-group-id="5323036112-3">(</span><span class="n">Var1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">VarN</span><span class="p" data-group-id="5323036112-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="5323036112-2">)</span><span class="p">.</span></code></pre><p>A macro definition can be placed anywhere among the attributes and function
│ │ │ │  declarations of a module, but the definition must come before any usage of the
│ │ │ │  macro.</p><p>If a macro is used in several modules, it is recommended that the macro
│ │ │ │  definition is placed in an include file.</p><p>A macro is used as follows:</p><pre><code class="text">?Const
│ │ │ │  ?Func(Arg1,...,ArgN)</code></pre><p>Macros are expanded during compilation. A simple macro <code class="inline">?Const</code> is replaced with
│ │ │ │ -<code class="inline">Replacement</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="4730934176-1">(</span><span class="n">TIMEOUT</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="4730934176-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">Replacement</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7536848980-1">(</span><span class="n">TIMEOUT</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="7536848980-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">call</span><span class="p" data-group-id="4730934176-2">(</span><span class="n">Request</span><span class="p" data-group-id="4730934176-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="4730934176-3">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">TIMEOUT</span><span class="p" data-group-id="4730934176-3">)</span><span class="p">.</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">call</span><span class="p" data-group-id="8074230553-1">(</span><span class="n">Request</span><span class="p" data-group-id="8074230553-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="8074230553-2">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="8074230553-2">)</span><span class="p">.</span></code></pre><p>A macro <code class="inline">?Func(Arg1,...,ArgN)</code> is replaced with <code class="inline">Replacement</code>, where all
│ │ │ │ +</span><span class="nf">call</span><span class="p" data-group-id="7536848980-2">(</span><span class="n">Request</span><span class="p" data-group-id="7536848980-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="7536848980-3">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">TIMEOUT</span><span class="p" data-group-id="7536848980-3">)</span><span class="p">.</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">call</span><span class="p" data-group-id="0528292836-1">(</span><span class="n">Request</span><span class="p" data-group-id="0528292836-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="0528292836-2">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="0528292836-2">)</span><span class="p">.</span></code></pre><p>A macro <code class="inline">?Func(Arg1,...,ArgN)</code> is replaced with <code class="inline">Replacement</code>, where all
│ │ │ │  occurrences of a variable <code class="inline">Var</code> from the macro definition are replaced with the
│ │ │ │ -corresponding argument <code class="inline">Arg</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0467337080-1">(</span><span class="n">MACRO1</span><span class="p" data-group-id="0467337080-2">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0467337080-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0467337080-3">{</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0467337080-3">}</span><span class="p" data-group-id="0467337080-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +corresponding argument <code class="inline">Arg</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0463774539-1">(</span><span class="n">MACRO1</span><span class="p" data-group-id="0463774539-2">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0463774539-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0463774539-3">{</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0463774539-3">}</span><span class="p" data-group-id="0463774539-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="0467337080-4">(</span><span class="n">X</span><span class="p" data-group-id="0467337080-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="0467337080-5">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="0467337080-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="0467337080-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="mi">123</span><span class="p" data-group-id="0467337080-6">)</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="0925797115-1">(</span><span class="n">X</span><span class="p" data-group-id="0925797115-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0925797115-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0925797115-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0925797115-3">{</span><span class="ss">a</span><span class="p">,</span><span class="n">X</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">123</span><span class="p" data-group-id="0925797115-3">}</span><span class="p">.</span></code></pre><p>It is good programming practice, but not mandatory, to ensure that a macro
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="0463774539-4">(</span><span class="n">X</span><span class="p" data-group-id="0463774539-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="0463774539-5">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="0463774539-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="0463774539-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="mi">123</span><span class="p" data-group-id="0463774539-6">)</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="3340763239-1">(</span><span class="n">X</span><span class="p" data-group-id="3340763239-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3340763239-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3340763239-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3340763239-3">{</span><span class="ss">a</span><span class="p">,</span><span class="n">X</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">123</span><span class="p" data-group-id="3340763239-3">}</span><span class="p">.</span></code></pre><p>It is good programming practice, but not mandatory, to ensure that a macro
│ │ │ │  definition is a valid Erlang syntactic form.</p><p>To view the result of macro expansion, a module can be compiled with the <code class="inline">'P'</code>
│ │ │ │  option. <code class="inline">compile:file(File, ['P'])</code>. This produces a listing of the parsed code
│ │ │ │  after preprocessing and parse transforms, in the file <code class="inline">File.P</code>.</p><h2 id="predefined-macros" class="section-heading">
│ │ │ │    <a href="#predefined-macros" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Predefined Macros</span>
│ │ │ │ @@ -90,29 +90,29 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Macros Overloading</span>
│ │ │ │  </h2>
│ │ │ │  <p>It is possible to overload macros, except for predefined macros. An overloaded
│ │ │ │  macro has more than one definition, each with a different number of arguments.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Support for overloading of macros was added in Erlang 5.7.5/OTP R13B04.</p></section><p>A macro <code class="inline">?Func(Arg1,...,ArgN)</code> with a (possibly empty) list of arguments results
│ │ │ │  in an error message if there is at least one definition of <code class="inline">Func</code> with
│ │ │ │ -arguments, but none with N arguments.</p><p>Assuming these definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0414274021-1">(</span><span class="n">F0</span><span class="p" data-group-id="0414274021-2">(</span><span class="p" data-group-id="0414274021-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="0414274021-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0414274021-3">(</span><span class="n">F1</span><span class="p" data-group-id="0414274021-4">(</span><span class="n">A</span><span class="p" data-group-id="0414274021-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="0414274021-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0414274021-5">(</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="nc">m</span><span class="p">:</span><span class="ss">f</span><span class="p" data-group-id="0414274021-5">)</span><span class="p">.</span></code></pre><p>the following does not work:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f0</span><span class="p" data-group-id="3976456800-1">(</span><span class="p" data-group-id="3976456800-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +arguments, but none with N arguments.</p><p>Assuming these definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0463622345-1">(</span><span class="n">F0</span><span class="p" data-group-id="0463622345-2">(</span><span class="p" data-group-id="0463622345-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="0463622345-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0463622345-3">(</span><span class="n">F1</span><span class="p" data-group-id="0463622345-4">(</span><span class="n">A</span><span class="p" data-group-id="0463622345-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="0463622345-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0463622345-5">(</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="nc">m</span><span class="p">:</span><span class="ss">f</span><span class="p" data-group-id="0463622345-5">)</span><span class="p">.</span></code></pre><p>the following does not work:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f0</span><span class="p" data-group-id="6340392429-1">(</span><span class="p" data-group-id="6340392429-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="o">?</span><span class="n">F0</span><span class="p">.</span><span class="w"> </span><span class="c1">% No, an empty list of arguments expected.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">f1</span><span class="p" data-group-id="3976456800-2">(</span><span class="n">A</span><span class="p" data-group-id="3976456800-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="o">?</span><span class="n">F1</span><span class="p" data-group-id="3976456800-3">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="3976456800-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% No, exactly one argument expected.</span></code></pre><p>On the other hand,</p><pre><code class="text">f() -&gt;
│ │ │ │ -    ?C().</code></pre><p>is expanded to</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="0977459351-1">(</span><span class="p" data-group-id="0977459351-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">m</span><span class="p">:</span><span class="nf">f</span><span class="p" data-group-id="0977459351-2">(</span><span class="p" data-group-id="0977459351-2">)</span><span class="p">.</span></code></pre><h2 id="removing-a-macro-definition" class="section-heading">
│ │ │ │ +</span><span class="nf">f1</span><span class="p" data-group-id="6340392429-2">(</span><span class="n">A</span><span class="p" data-group-id="6340392429-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="o">?</span><span class="n">F1</span><span class="p" data-group-id="6340392429-3">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="6340392429-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% No, exactly one argument expected.</span></code></pre><p>On the other hand,</p><pre><code class="text">f() -&gt;
│ │ │ │ +    ?C().</code></pre><p>is expanded to</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="8097828819-1">(</span><span class="p" data-group-id="8097828819-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">m</span><span class="p">:</span><span class="nf">f</span><span class="p" data-group-id="8097828819-2">(</span><span class="p" data-group-id="8097828819-2">)</span><span class="p">.</span></code></pre><h2 id="removing-a-macro-definition" class="section-heading">
│ │ │ │    <a href="#removing-a-macro-definition" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Removing a macro definition</span>
│ │ │ │  </h2>
│ │ │ │ -<p>A definition of macro can be removed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">undef</span><span class="p" data-group-id="9374142105-1">(</span><span class="n">Macro</span><span class="p" data-group-id="9374142105-1">)</span><span class="p">.</span></code></pre><h2 id="conditional-compilation" class="section-heading">
│ │ │ │ +<p>A definition of macro can be removed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">undef</span><span class="p" data-group-id="7596196777-1">(</span><span class="n">Macro</span><span class="p" data-group-id="7596196777-1">)</span><span class="p">.</span></code></pre><h2 id="conditional-compilation" class="section-heading">
│ │ │ │    <a href="#conditional-compilation" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Conditional Compilation</span>
│ │ │ │  </h2>
│ │ │ │  <p>The following macro directives support conditional compilation:</p><ul><li><p><strong><code class="inline">-ifdef(Macro).</code></strong> - Evaluate the following lines only if <code class="inline">Macro</code> is
│ │ │ │  defined.</p></li><li><p><strong><code class="inline">-ifndef(Macro).</code></strong> - Evaluate the following lines only if <code class="inline">Macro</code> is not
│ │ │ │ @@ -124,43 +124,43 @@
│ │ │ │  true, and the <code class="inline">Condition</code> evaluates to true, the lines following the <code class="inline">elif</code>
│ │ │ │  are evaluated instead.</p></li><li><p><strong><code class="inline">-endif.</code></strong> - Specifies the end of a series of control flow directives.</p></li></ul><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Macro directives cannot be used inside functions.</p></section><p>Syntactically, the <code class="inline">Condition</code> in <code class="inline">if</code> and <code class="inline">elif</code> must be a
│ │ │ │  <a href="expressions.xhtml#guard-expressions">guard expression</a>. Other constructs (such as
│ │ │ │  a <code class="inline">case</code> expression) result in a compilation error.</p><p>As opposed to the standard guard expressions, an expression in an <code class="inline">if</code> and
│ │ │ │  <code class="inline">elif</code> also supports calling the psuedo-function <code class="inline">defined(Name)</code>, which tests
│ │ │ │  whether the <code class="inline">Name</code> argument is the name of a previously defined macro.
│ │ │ │  <code class="inline">defined(Name)</code> evaluates to <code class="inline">true</code> if the macro is defined and <code class="inline">false</code>
│ │ │ │ -otherwise. An attempt to call other functions results in a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2753016269-1">(</span><span class="ss">m</span><span class="p" data-group-id="2753016269-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +otherwise. An attempt to call other functions results in a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4845469906-1">(</span><span class="ss">m</span><span class="p" data-group-id="4845469906-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="2753016269-2">(</span><span class="ss">debug</span><span class="p" data-group-id="2753016269-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2753016269-3">(</span><span class="n">LOG</span><span class="p" data-group-id="2753016269-4">(</span><span class="n">X</span><span class="p" data-group-id="2753016269-4">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2753016269-5">(</span><span class="s">&quot;{</span><span class="si">~p</span><span class="s">,</span><span class="si">~p</span><span class="s">}: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2753016269-6">[</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="o">?</span><span class="n">LINE</span><span class="p">,</span><span class="n">X</span><span class="p" data-group-id="2753016269-6">]</span><span class="p" data-group-id="2753016269-5">)</span><span class="p" data-group-id="2753016269-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="4845469906-2">(</span><span class="ss">debug</span><span class="p" data-group-id="4845469906-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="4845469906-3">(</span><span class="n">LOG</span><span class="p" data-group-id="4845469906-4">(</span><span class="n">X</span><span class="p" data-group-id="4845469906-4">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4845469906-5">(</span><span class="s">&quot;{</span><span class="si">~p</span><span class="s">,</span><span class="si">~p</span><span class="s">}: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4845469906-6">[</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="o">?</span><span class="n">LINE</span><span class="p">,</span><span class="n">X</span><span class="p" data-group-id="4845469906-6">]</span><span class="p" data-group-id="4845469906-5">)</span><span class="p" data-group-id="4845469906-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2753016269-7">(</span><span class="n">LOG</span><span class="p" data-group-id="2753016269-8">(</span><span class="n">X</span><span class="p" data-group-id="2753016269-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2753016269-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="4845469906-7">(</span><span class="n">LOG</span><span class="p" data-group-id="4845469906-8">(</span><span class="n">X</span><span class="p" data-group-id="4845469906-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="4845469906-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>When trace output is desired, <code class="inline">debug</code> is to be defined when the module <code class="inline">m</code> is
│ │ │ │  compiled:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erlc -Ddebug m.erl</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="ow">or</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="0458204949-1">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0458204949-2">{</span><span class="ss">d</span><span class="p">,</span><span class="w"> </span><span class="ss">debug</span><span class="p" data-group-id="0458204949-2">}</span><span class="p" data-group-id="0458204949-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0458204949-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">m</span><span class="p" data-group-id="0458204949-3">}</span></code></pre><p><code class="inline">?LOG(Arg)</code> is then expanded to a call to <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> and provide the user
│ │ │ │ -with some simple trace output.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9557999326-1">(</span><span class="ss">m</span><span class="p" data-group-id="9557999326-1">)</span><span class="w">
│ │ │ │ +</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="7664998292-1">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7664998292-2">{</span><span class="ss">d</span><span class="p">,</span><span class="w"> </span><span class="ss">debug</span><span class="p" data-group-id="7664998292-2">}</span><span class="p" data-group-id="7664998292-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7664998292-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">m</span><span class="p" data-group-id="7664998292-3">}</span></code></pre><p><code class="inline">?LOG(Arg)</code> is then expanded to a call to <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> and provide the user
│ │ │ │ +with some simple trace output.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0907990917-1">(</span><span class="ss">m</span><span class="p" data-group-id="0907990917-1">)</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="9557999326-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">25</span><span class="p" data-group-id="9557999326-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="0907990917-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">25</span><span class="p" data-group-id="0907990917-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% Code that will work in OTP 25 or higher</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">elif</span><span class="p" data-group-id="9557999326-3">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="p" data-group-id="9557999326-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">elif</span><span class="p" data-group-id="0907990917-3">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="p" data-group-id="0907990917-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% Code that will work in OTP 26 or higher</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% Code that will work in OTP 24 or lower.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This code uses the <code class="inline">OTP_RELEASE</code> macro to conditionally select code depending on
│ │ │ │ -release.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7340958398-1">(</span><span class="ss">m</span><span class="p" data-group-id="7340958398-1">)</span><span class="w">
│ │ │ │ +release.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4003919933-1">(</span><span class="ss">m</span><span class="p" data-group-id="4003919933-1">)</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="7340958398-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">defined</span><span class="p" data-group-id="7340958398-3">(</span><span class="ss">debug</span><span class="p" data-group-id="7340958398-3">)</span><span class="p" data-group-id="7340958398-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="4003919933-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">defined</span><span class="p" data-group-id="4003919933-3">(</span><span class="ss">debug</span><span class="p" data-group-id="4003919933-3">)</span><span class="p" data-group-id="4003919933-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% Debugging code that requires OTP 26 or later.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% Non-debug code that works in any release.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This code uses the <code class="inline">OTP_RELEASE</code> macro and <code class="inline">defined(debug)</code> to compile debug
│ │ │ │  code only for OTP 26 or later.</p><h2 id="the-feature-directive" class="section-heading">
│ │ │ │    <a href="#the-feature-directive" class="hover-link">
│ │ │ │ @@ -175,40 +175,40 @@
│ │ │ │  used. In practice this means it should appear before any <code class="inline">-export(..)</code> or record
│ │ │ │  definitions.</p><h2 id="error-and-warning-directives" class="section-heading">
│ │ │ │    <a href="#error-and-warning-directives" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">-error() and -warning() directives</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The directive <code class="inline">-error(Term)</code> causes a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6839950963-1">(</span><span class="ss">t</span><span class="p" data-group-id="6839950963-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6839950963-2">(</span><span class="p" data-group-id="6839950963-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6839950963-3">]</span><span class="p" data-group-id="6839950963-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>The directive <code class="inline">-error(Term)</code> causes a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3606593693-1">(</span><span class="ss">t</span><span class="p" data-group-id="3606593693-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3606593693-2">(</span><span class="p" data-group-id="3606593693-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3606593693-3">]</span><span class="p" data-group-id="3606593693-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="6839950963-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="6839950963-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">version</span><span class="p" data-group-id="6839950963-5">(</span><span class="p" data-group-id="6839950963-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="3606593693-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="3606593693-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">version</span><span class="p" data-group-id="3606593693-5">(</span><span class="p" data-group-id="3606593693-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">error</span><span class="p" data-group-id="6839950963-6">(</span><span class="s">&quot;Macro VERSION must be defined.&quot;</span><span class="p" data-group-id="6839950963-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">version</span><span class="p" data-group-id="6839950963-7">(</span><span class="p" data-group-id="6839950963-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">error</span><span class="p" data-group-id="3606593693-6">(</span><span class="s">&quot;Macro VERSION must be defined.&quot;</span><span class="p" data-group-id="3606593693-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">version</span><span class="p" data-group-id="3606593693-7">(</span><span class="p" data-group-id="3606593693-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span></code></pre><p>The error message will look like this:</p><pre><code class="text">% erlc t.erl
│ │ │ │ -t.erl:7: -error(&quot;Macro VERSION must be defined.&quot;).</code></pre><p>The directive <code class="inline">-warning(Term)</code> causes a compilation warning.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0141458503-1">(</span><span class="ss">t</span><span class="p" data-group-id="0141458503-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0141458503-2">(</span><span class="p" data-group-id="0141458503-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0141458503-3">]</span><span class="p" data-group-id="0141458503-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +t.erl:7: -error(&quot;Macro VERSION must be defined.&quot;).</code></pre><p>The directive <code class="inline">-warning(Term)</code> causes a compilation warning.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0065789345-1">(</span><span class="ss">t</span><span class="p" data-group-id="0065789345-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0065789345-2">(</span><span class="p" data-group-id="0065789345-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0065789345-3">]</span><span class="p" data-group-id="0065789345-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">ifndef</span><span class="p" data-group-id="0141458503-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="0141458503-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">warning</span><span class="p" data-group-id="0141458503-5">(</span><span class="s">&quot;Macro VERSION not defined -- using default version.&quot;</span><span class="p" data-group-id="0141458503-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0141458503-6">(</span><span class="n">VERSION</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;0&quot;</span><span class="p" data-group-id="0141458503-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">ifndef</span><span class="p" data-group-id="0065789345-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="0065789345-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">warning</span><span class="p" data-group-id="0065789345-5">(</span><span class="s">&quot;Macro VERSION not defined -- using default version.&quot;</span><span class="p" data-group-id="0065789345-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0065789345-6">(</span><span class="n">VERSION</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;0&quot;</span><span class="p" data-group-id="0065789345-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">version</span><span class="p" data-group-id="0141458503-7">(</span><span class="p" data-group-id="0141458503-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span></code></pre><p>The warning message will look like this:</p><pre><code class="text">% erlc t.erl
│ │ │ │ +</span><span class="nf">version</span><span class="p" data-group-id="0065789345-7">(</span><span class="p" data-group-id="0065789345-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span></code></pre><p>The warning message will look like this:</p><pre><code class="text">% erlc t.erl
│ │ │ │  t.erl:5: Warning: -warning(&quot;Macro VERSION not defined -- using default version.&quot;).</code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>The <code class="inline">-error()</code> and <code class="inline">-warning()</code> directives were added in Erlang/OTP 19.</p></section><h2 id="stringifying-macro-arguments" class="section-heading">
│ │ │ │    <a href="#stringifying-macro-arguments" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Stringifying Macro Arguments</span>
│ │ │ │  </h2>
│ │ │ │  <p>The construction <code class="inline">??Arg</code>, where <code class="inline">Arg</code> is a macro argument, is expanded to a
│ │ │ │  string containing the tokens of the argument. This is similar to the <code class="inline">#arg</code>
│ │ │ │ -stringifying construction in C.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="4149560003-1">(</span><span class="n">TESTCALL</span><span class="p" data-group-id="4149560003-2">(</span><span class="n">Call</span><span class="p" data-group-id="4149560003-2">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4149560003-3">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4149560003-4">[</span><span class="o">?</span><span class="o">?</span><span class="n">Call</span><span class="p">,</span><span class="w"> </span><span class="n">Call</span><span class="p" data-group-id="4149560003-4">]</span><span class="p" data-group-id="4149560003-3">)</span><span class="p" data-group-id="4149560003-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +stringifying construction in C.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5297937875-1">(</span><span class="n">TESTCALL</span><span class="p" data-group-id="5297937875-2">(</span><span class="n">Call</span><span class="p" data-group-id="5297937875-2">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5297937875-3">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5297937875-4">[</span><span class="o">?</span><span class="o">?</span><span class="n">Call</span><span class="p">,</span><span class="w"> </span><span class="n">Call</span><span class="p" data-group-id="5297937875-4">]</span><span class="p" data-group-id="5297937875-3">)</span><span class="p" data-group-id="5297937875-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="4149560003-5">(</span><span class="nf">myfunction</span><span class="p" data-group-id="4149560003-6">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4149560003-6">)</span><span class="p" data-group-id="4149560003-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="4149560003-7">(</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="4149560003-8">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="4149560003-8">)</span><span class="p" data-group-id="4149560003-7">)</span><span class="p">.</span></code></pre><p>results in</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7728321854-1">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="7728321854-2">[</span><span class="s">&quot;myfunction ( 1 , 2 )&quot;</span><span class="p">,</span><span class="nf">myfunction</span><span class="p" data-group-id="7728321854-3">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7728321854-3">)</span><span class="p" data-group-id="7728321854-2">]</span><span class="p" data-group-id="7728321854-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7728321854-4">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="7728321854-5">[</span><span class="s">&quot;you : function ( 2 , 1 )&quot;</span><span class="p">,</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="7728321854-6">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="7728321854-6">)</span><span class="p" data-group-id="7728321854-5">]</span><span class="p" data-group-id="7728321854-4">)</span><span class="p">.</span></code></pre><p>That is, a trace output, with both the function called and the resulting value.</p>
│ │ │ │ +</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="5297937875-5">(</span><span class="nf">myfunction</span><span class="p" data-group-id="5297937875-6">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5297937875-6">)</span><span class="p" data-group-id="5297937875-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="5297937875-7">(</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="5297937875-8">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5297937875-8">)</span><span class="p" data-group-id="5297937875-7">)</span><span class="p">.</span></code></pre><p>results in</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5375807850-1">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="5375807850-2">[</span><span class="s">&quot;myfunction ( 1 , 2 )&quot;</span><span class="p">,</span><span class="nf">myfunction</span><span class="p" data-group-id="5375807850-3">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5375807850-3">)</span><span class="p" data-group-id="5375807850-2">]</span><span class="p" data-group-id="5375807850-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5375807850-4">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="5375807850-5">[</span><span class="s">&quot;you : function ( 2 , 1 )&quot;</span><span class="p">,</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="5375807850-6">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5375807850-6">)</span><span class="p" data-group-id="5375807850-5">]</span><span class="p" data-group-id="5375807850-4">)</span><span class="p">.</span></code></pre><p>That is, a trace output, with both the function called and the resulting value.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/listhandling.xhtml
│ │ │ │ @@ -25,101 +25,101 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Creating a List</span>
│ │ │ │  </h2>
│ │ │ │  <p>Lists can only be built starting from the end and attaching list elements at the
│ │ │ │  beginning. If you use the <code class="inline">++</code> operator as follows, a new list is created that
│ │ │ │  is a copy of the elements in <code class="inline">List1</code>, followed by <code class="inline">List2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">List1</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">List2</span></code></pre><p>Looking at how <a href="../../../lib/stdlib/doc/html/lists.html#append/2"><code class="inline">lists:append/2</code></a> or <code class="inline">++</code> would be implemented in plain Erlang,
│ │ │ │ -clearly the first list is copied:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="4215279265-1">(</span><span class="p" data-group-id="4215279265-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4215279265-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="4215279265-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4215279265-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">append</span><span class="p" data-group-id="4215279265-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="4215279265-4">)</span><span class="p" data-group-id="4215279265-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">append</span><span class="p" data-group-id="4215279265-5">(</span><span class="p" data-group-id="4215279265-6">[</span><span class="p" data-group-id="4215279265-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="4215279265-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +clearly the first list is copied:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="9566882333-1">(</span><span class="p" data-group-id="9566882333-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9566882333-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9566882333-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9566882333-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">append</span><span class="p" data-group-id="9566882333-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9566882333-4">)</span><span class="p" data-group-id="9566882333-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">append</span><span class="p" data-group-id="9566882333-5">(</span><span class="p" data-group-id="9566882333-6">[</span><span class="p" data-group-id="9566882333-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9566882333-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Tail</span><span class="p">.</span></code></pre><p>When recursing and building a list, it is important to ensure that you attach
│ │ │ │  the new elements to the beginning of the list. In this way, you will build <em>one</em>
│ │ │ │ -list, not hundreds or thousands of copies of the growing result list.</p><p>Let us first see how it is not to be done:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">bad_fib</span><span class="p" data-group-id="5894300627-1">(</span><span class="n">N</span><span class="p" data-group-id="5894300627-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">bad_fib</span><span class="p" data-group-id="5894300627-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5894300627-3">[</span><span class="p" data-group-id="5894300627-3">]</span><span class="p" data-group-id="5894300627-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +list, not hundreds or thousands of copies of the growing result list.</p><p>Let us first see how it is not to be done:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">bad_fib</span><span class="p" data-group-id="3870497029-1">(</span><span class="n">N</span><span class="p" data-group-id="3870497029-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">bad_fib</span><span class="p" data-group-id="3870497029-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3870497029-3">[</span><span class="p" data-group-id="3870497029-3">]</span><span class="p" data-group-id="3870497029-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">bad_fib</span><span class="p" data-group-id="5894300627-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="5894300627-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">bad_fib</span><span class="p" data-group-id="3870497029-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="3870497029-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Fibs</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">bad_fib</span><span class="p" data-group-id="5894300627-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="5894300627-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">bad_fib</span><span class="p" data-group-id="5894300627-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="5894300627-7">[</span><span class="n">Current</span><span class="p" data-group-id="5894300627-7">]</span><span class="p" data-group-id="5894300627-6">)</span><span class="p">.</span></code></pre><p>Here more than one list is built. In each iteration step a new list is created
│ │ │ │ +</span><span class="nf">bad_fib</span><span class="p" data-group-id="3870497029-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="3870497029-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">bad_fib</span><span class="p" data-group-id="3870497029-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="3870497029-7">[</span><span class="n">Current</span><span class="p" data-group-id="3870497029-7">]</span><span class="p" data-group-id="3870497029-6">)</span><span class="p">.</span></code></pre><p>Here more than one list is built. In each iteration step a new list is created
│ │ │ │  that is one element longer than the new previous list.</p><p>To avoid copying the result in each iteration, build the list in reverse order
│ │ │ │ -and reverse the list when you are done:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4182091423-1">(</span><span class="n">N</span><span class="p" data-group-id="4182091423-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4182091423-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4182091423-3">[</span><span class="p" data-group-id="4182091423-3">]</span><span class="p" data-group-id="4182091423-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +and reverse the list when you are done:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4515968695-1">(</span><span class="n">N</span><span class="p" data-group-id="4515968695-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4515968695-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4515968695-3">[</span><span class="p" data-group-id="4515968695-3">]</span><span class="p" data-group-id="4515968695-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4182091423-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="4182091423-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="4182091423-5">(</span><span class="n">Fibs</span><span class="p" data-group-id="4182091423-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4182091423-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="4182091423-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4182091423-7">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4182091423-8">[</span><span class="n">Current</span><span class="p">|</span><span class="n">Fibs</span><span class="p" data-group-id="4182091423-8">]</span><span class="p" data-group-id="4182091423-7">)</span><span class="p">.</span></code></pre><h2 id="list-comprehensions" class="section-heading">
│ │ │ │ +</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4515968695-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="4515968695-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="4515968695-5">(</span><span class="n">Fibs</span><span class="p" data-group-id="4515968695-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4515968695-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="4515968695-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="4515968695-7">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4515968695-8">[</span><span class="n">Current</span><span class="p">|</span><span class="n">Fibs</span><span class="p" data-group-id="4515968695-8">]</span><span class="p" data-group-id="4515968695-7">)</span><span class="p">.</span></code></pre><h2 id="list-comprehensions" class="section-heading">
│ │ │ │    <a href="#list-comprehensions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">List Comprehensions</span>
│ │ │ │  </h2>
│ │ │ │ -<p>A list comprehension:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2990088389-1">[</span><span class="n">Expr</span><span class="p" data-group-id="2990088389-2">(</span><span class="n">E</span><span class="p" data-group-id="2990088389-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2990088389-1">]</span></code></pre><p>is basically translated to a local function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="2667097734-1">(</span><span class="p" data-group-id="2667097734-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="2667097734-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="2667097734-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2667097734-3">[</span><span class="n">Expr</span><span class="p" data-group-id="2667097734-4">(</span><span class="n">E</span><span class="p" data-group-id="2667097734-4">)</span><span class="p">|</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="2667097734-5">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="2667097734-5">)</span><span class="p" data-group-id="2667097734-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="2667097734-6">(</span><span class="p" data-group-id="2667097734-7">[</span><span class="p" data-group-id="2667097734-7">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="2667097734-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2667097734-8">[</span><span class="p" data-group-id="2667097734-8">]</span><span class="p">.</span></code></pre><p>If the result of the list comprehension will <em>obviously</em> not be used, a list
│ │ │ │ -will not be constructed. For example, in this code:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9554966341-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="9554966341-2">(</span><span class="n">E</span><span class="p" data-group-id="9554966341-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="9554966341-1">]</span><span class="p">,</span><span class="w">
│ │ │ │ +<p>A list comprehension:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5048484221-1">[</span><span class="n">Expr</span><span class="p" data-group-id="5048484221-2">(</span><span class="n">E</span><span class="p" data-group-id="5048484221-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5048484221-1">]</span></code></pre><p>is basically translated to a local function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="6316864201-1">(</span><span class="p" data-group-id="6316864201-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="6316864201-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="6316864201-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6316864201-3">[</span><span class="n">Expr</span><span class="p" data-group-id="6316864201-4">(</span><span class="n">E</span><span class="p" data-group-id="6316864201-4">)</span><span class="p">|</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="6316864201-5">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="6316864201-5">)</span><span class="p" data-group-id="6316864201-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="6316864201-6">(</span><span class="p" data-group-id="6316864201-7">[</span><span class="p" data-group-id="6316864201-7">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="6316864201-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6316864201-8">[</span><span class="p" data-group-id="6316864201-8">]</span><span class="p">.</span></code></pre><p>If the result of the list comprehension will <em>obviously</em> not be used, a list
│ │ │ │ +will not be constructed. For example, in this code:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5762082165-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="5762082165-2">(</span><span class="n">E</span><span class="p" data-group-id="5762082165-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5762082165-1">]</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>or in this code:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">Var</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="5816935668-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="5816935668-2">(</span><span class="n">E</span><span class="p" data-group-id="5816935668-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5816935668-1">]</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="4118892665-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="4118892665-2">(</span><span class="n">E</span><span class="p" data-group-id="4118892665-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="4118892665-1">]</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nf">some_function</span><span class="p" data-group-id="5816935668-3">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5816935668-3">)</span><span class="p">,</span></code></pre><p>the value is not assigned to a variable, not passed to another function, and not
│ │ │ │ +</span><span class="nf">some_function</span><span class="p" data-group-id="4118892665-3">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4118892665-3">)</span><span class="p">,</span></code></pre><p>the value is not assigned to a variable, not passed to another function, and not
│ │ │ │  returned. This means that there is no need to construct a list and the compiler
│ │ │ │ -will simplify the code for the list comprehension to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="1962749664-1">(</span><span class="p" data-group-id="1962749664-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="1962749664-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="1962749664-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Expr</span><span class="p" data-group-id="1962749664-3">(</span><span class="n">E</span><span class="p" data-group-id="1962749664-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="1962749664-4">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="1962749664-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="1962749664-5">(</span><span class="p" data-group-id="1962749664-6">[</span><span class="p" data-group-id="1962749664-6">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="1962749664-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1962749664-7">[</span><span class="p" data-group-id="1962749664-7">]</span><span class="p">.</span></code></pre><p>The compiler also understands that assigning to <code class="inline">_</code> means that the value will
│ │ │ │ -not be used. Therefore, the code in the following example will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1778665368-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="1778665368-2">(</span><span class="n">E</span><span class="p" data-group-id="1778665368-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="1778665368-1">]</span><span class="p">,</span><span class="w">
│ │ │ │ +will simplify the code for the list comprehension to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="4840777557-1">(</span><span class="p" data-group-id="4840777557-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="4840777557-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="4840777557-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Expr</span><span class="p" data-group-id="4840777557-3">(</span><span class="n">E</span><span class="p" data-group-id="4840777557-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="4840777557-4">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="4840777557-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="4840777557-5">(</span><span class="p" data-group-id="4840777557-6">[</span><span class="p" data-group-id="4840777557-6">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="4840777557-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4840777557-7">[</span><span class="p" data-group-id="4840777557-7">]</span><span class="p">.</span></code></pre><p>The compiler also understands that assigning to <code class="inline">_</code> means that the value will
│ │ │ │ +not be used. Therefore, the code in the following example will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4404094665-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="4404094665-2">(</span><span class="n">E</span><span class="p" data-group-id="4404094665-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="4404094665-1">]</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="p">.</span></code></pre><h2 id="deep-and-flat-lists" class="section-heading">
│ │ │ │    <a href="#deep-and-flat-lists" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Deep and Flat Lists</span>
│ │ │ │  </h2>
│ │ │ │  <p><a href="../../../lib/stdlib/doc/html/lists.html#flatten/1"><code class="inline">lists:flatten/1</code></a> builds an entirely new list. It is therefore expensive, and
│ │ │ │  even <em>more</em> expensive than the <code class="inline">++</code> operator (which copies its left argument,
│ │ │ │  but not its right argument).</p><p>In the following situations it is unnecessary to call <a href="../../../lib/stdlib/doc/html/lists.html#flatten/1"><code class="inline">lists:flatten/1</code></a>:</p><ul><li>When sending data to a port. Ports understand deep lists so there is no reason
│ │ │ │  to flatten the list before sending it to the port.</li><li>When calling BIFs that accept deep lists, such as
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#list_to_binary/1"><code class="inline">list_to_binary/1</code></a> or
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#iolist_to_binary/1"><code class="inline">iolist_to_binary/1</code></a>.</li><li>When you know that your list is only one level deep. Use <a href="../../../lib/stdlib/doc/html/lists.html#append/1"><code class="inline">lists:append/1</code></a>
│ │ │ │ -instead.</li></ul><p><em>Examples:</em></p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="1029625588-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">DeepList</span><span class="p" data-group-id="1029625588-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="0648041723-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="0648041723-2">(</span><span class="n">DeepList</span><span class="p" data-group-id="0648041723-2">)</span><span class="p" data-group-id="0648041723-1">)</span></code></pre><p>A common way to send a zero-terminated string to a port is the following:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">String</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6744543023-1">[</span><span class="mi">0</span><span class="p" data-group-id="6744543023-1">]</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nf">port_command</span><span class="p" data-group-id="6744543023-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="6744543023-2">)</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4189229540-1">[</span><span class="n">String</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4189229540-1">]</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nf">port_command</span><span class="p" data-group-id="4189229540-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="4189229540-2">)</span></code></pre><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">append</span><span class="p" data-group-id="1458705621-1">(</span><span class="p" data-group-id="1458705621-2">[</span><span class="p" data-group-id="1458705621-3">[</span><span class="mi">1</span><span class="p" data-group-id="1458705621-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1458705621-4">[</span><span class="mi">2</span><span class="p" data-group-id="1458705621-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1458705621-5">[</span><span class="mi">3</span><span class="p" data-group-id="1458705621-5">]</span><span class="p" data-group-id="1458705621-2">]</span><span class="p" data-group-id="1458705621-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1458705621-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1458705621-6">]</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="8369200135-1">(</span><span class="p" data-group-id="8369200135-2">[</span><span class="p" data-group-id="8369200135-3">[</span><span class="mi">1</span><span class="p" data-group-id="8369200135-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8369200135-4">[</span><span class="mi">2</span><span class="p" data-group-id="8369200135-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8369200135-5">[</span><span class="mi">3</span><span class="p" data-group-id="8369200135-5">]</span><span class="p" data-group-id="8369200135-2">]</span><span class="p" data-group-id="8369200135-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8369200135-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8369200135-6">]</span></code></pre><h2 id="recursive-list-functions" class="section-heading">
│ │ │ │ +instead.</li></ul><p><em>Examples:</em></p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="3317991384-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">DeepList</span><span class="p" data-group-id="3317991384-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="5212074043-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="5212074043-2">(</span><span class="n">DeepList</span><span class="p" data-group-id="5212074043-2">)</span><span class="p" data-group-id="5212074043-1">)</span></code></pre><p>A common way to send a zero-terminated string to a port is the following:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">String</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="1580759125-1">[</span><span class="mi">0</span><span class="p" data-group-id="1580759125-1">]</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">port_command</span><span class="p" data-group-id="1580759125-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="1580759125-2">)</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0648880560-1">[</span><span class="n">String</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="0648880560-1">]</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">port_command</span><span class="p" data-group-id="0648880560-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="0648880560-2">)</span></code></pre><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">append</span><span class="p" data-group-id="8022253194-1">(</span><span class="p" data-group-id="8022253194-2">[</span><span class="p" data-group-id="8022253194-3">[</span><span class="mi">1</span><span class="p" data-group-id="8022253194-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8022253194-4">[</span><span class="mi">2</span><span class="p" data-group-id="8022253194-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8022253194-5">[</span><span class="mi">3</span><span class="p" data-group-id="8022253194-5">]</span><span class="p" data-group-id="8022253194-2">]</span><span class="p" data-group-id="8022253194-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8022253194-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8022253194-6">]</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="9748940779-1">(</span><span class="p" data-group-id="9748940779-2">[</span><span class="p" data-group-id="9748940779-3">[</span><span class="mi">1</span><span class="p" data-group-id="9748940779-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9748940779-4">[</span><span class="mi">2</span><span class="p" data-group-id="9748940779-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9748940779-5">[</span><span class="mi">3</span><span class="p" data-group-id="9748940779-5">]</span><span class="p" data-group-id="9748940779-2">]</span><span class="p" data-group-id="9748940779-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9748940779-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9748940779-6">]</span></code></pre><h2 id="recursive-list-functions" class="section-heading">
│ │ │ │    <a href="#recursive-list-functions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Recursive List Functions</span>
│ │ │ │  </h2>
│ │ │ │  <p>There are two basic ways to write a function that traverses a list and
│ │ │ │  produces a new list.</p><p>The first way is writing a <em>body-recursive</em> function:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Add 42 to each integer in the list.</span><span class="w">
│ │ │ │ -</span><span class="nf">add_42_body</span><span class="p" data-group-id="0008289454-1">(</span><span class="p" data-group-id="0008289454-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0008289454-2">]</span><span class="p" data-group-id="0008289454-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0008289454-3">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">add_42_body</span><span class="p" data-group-id="0008289454-4">(</span><span class="n">T</span><span class="p" data-group-id="0008289454-4">)</span><span class="p" data-group-id="0008289454-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">add_42_body</span><span class="p" data-group-id="0008289454-5">(</span><span class="p" data-group-id="0008289454-6">[</span><span class="p" data-group-id="0008289454-6">]</span><span class="p" data-group-id="0008289454-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0008289454-7">[</span><span class="p" data-group-id="0008289454-7">]</span><span class="p">.</span></code></pre><p>The second way is writing a <em>tail-recursive</em> function:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Add 42 to each integer in the list.</span><span class="w">
│ │ │ │ -</span><span class="nf">add_42_tail</span><span class="p" data-group-id="3741447806-1">(</span><span class="n">List</span><span class="p" data-group-id="3741447806-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="3741447806-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3741447806-3">[</span><span class="p" data-group-id="3741447806-3">]</span><span class="p" data-group-id="3741447806-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add_42_body</span><span class="p" data-group-id="9817829677-1">(</span><span class="p" data-group-id="9817829677-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9817829677-2">]</span><span class="p" data-group-id="9817829677-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9817829677-3">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">add_42_body</span><span class="p" data-group-id="9817829677-4">(</span><span class="n">T</span><span class="p" data-group-id="9817829677-4">)</span><span class="p" data-group-id="9817829677-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">add_42_body</span><span class="p" data-group-id="9817829677-5">(</span><span class="p" data-group-id="9817829677-6">[</span><span class="p" data-group-id="9817829677-6">]</span><span class="p" data-group-id="9817829677-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9817829677-7">[</span><span class="p" data-group-id="9817829677-7">]</span><span class="p">.</span></code></pre><p>The second way is writing a <em>tail-recursive</em> function:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Add 42 to each integer in the list.</span><span class="w">
│ │ │ │ +</span><span class="nf">add_42_tail</span><span class="p" data-group-id="8670150726-1">(</span><span class="n">List</span><span class="p" data-group-id="8670150726-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="8670150726-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8670150726-3">[</span><span class="p" data-group-id="8670150726-3">]</span><span class="p" data-group-id="8670150726-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">add_42_tail</span><span class="p" data-group-id="3741447806-4">(</span><span class="p" data-group-id="3741447806-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3741447806-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3741447806-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="3741447806-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3741447806-7">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3741447806-7">]</span><span class="p" data-group-id="3741447806-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">add_42_tail</span><span class="p" data-group-id="3741447806-8">(</span><span class="p" data-group-id="3741447806-9">[</span><span class="p" data-group-id="3741447806-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3741447806-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="3741447806-10">(</span><span class="n">Acc</span><span class="p" data-group-id="3741447806-10">)</span><span class="p">.</span></code></pre><p>In early version of Erlang the tail-recursive function would typically
│ │ │ │ +</span><span class="nf">add_42_tail</span><span class="p" data-group-id="8670150726-4">(</span><span class="p" data-group-id="8670150726-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8670150726-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8670150726-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="8670150726-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8670150726-7">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8670150726-7">]</span><span class="p" data-group-id="8670150726-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">add_42_tail</span><span class="p" data-group-id="8670150726-8">(</span><span class="p" data-group-id="8670150726-9">[</span><span class="p" data-group-id="8670150726-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8670150726-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="8670150726-10">(</span><span class="n">Acc</span><span class="p" data-group-id="8670150726-10">)</span><span class="p">.</span></code></pre><p>In early version of Erlang the tail-recursive function would typically
│ │ │ │  be more efficient. In modern versions of Erlang, there is usually not
│ │ │ │  much difference in performance between a body-recursive list function and
│ │ │ │  tail-recursive function that reverses the list at the end. Therefore,
│ │ │ │  concentrate on writing beautiful code and forget about the performance
│ │ │ │  of your list functions. In the time-critical parts of your code,
│ │ │ │  <em>measure</em> before rewriting your code.</p><p>For a thorough discussion about tail and body recursion, see
│ │ │ │  <a href="http://ferd.ca/erlang-s-tail-recursion-is-not-a-silver-bullet.html">Erlang's Tail Recursion is Not a Silver Bullet</a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>This section is about list functions that <em>construct</em> lists. A tail-recursive
│ │ │ │  function that does not construct a list runs in constant space, while the
│ │ │ │  corresponding body-recursive function uses stack space proportional to the
│ │ │ │  length of the list.</p></section><p>For example, a function that sums a list of integers, is <em>not</em> to be written as
│ │ │ │ -follows:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">recursive_sum</span><span class="p" data-group-id="6866314200-1">(</span><span class="p" data-group-id="6866314200-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6866314200-2">]</span><span class="p" data-group-id="6866314200-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">H</span><span class="o">+</span><span class="nf">recursive_sum</span><span class="p" data-group-id="6866314200-3">(</span><span class="n">T</span><span class="p" data-group-id="6866314200-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">recursive_sum</span><span class="p" data-group-id="6866314200-4">(</span><span class="p" data-group-id="6866314200-5">[</span><span class="p" data-group-id="6866314200-5">]</span><span class="p" data-group-id="6866314200-4">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p">.</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">sum</span><span class="p" data-group-id="1529039755-1">(</span><span class="n">L</span><span class="p" data-group-id="1529039755-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="1529039755-2">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="1529039755-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +follows:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">recursive_sum</span><span class="p" data-group-id="7916129104-1">(</span><span class="p" data-group-id="7916129104-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7916129104-2">]</span><span class="p" data-group-id="7916129104-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">H</span><span class="o">+</span><span class="nf">recursive_sum</span><span class="p" data-group-id="7916129104-3">(</span><span class="n">T</span><span class="p" data-group-id="7916129104-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">recursive_sum</span><span class="p" data-group-id="7916129104-4">(</span><span class="p" data-group-id="7916129104-5">[</span><span class="p" data-group-id="7916129104-5">]</span><span class="p" data-group-id="7916129104-4">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p">.</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">sum</span><span class="p" data-group-id="3805073402-1">(</span><span class="n">L</span><span class="p" data-group-id="3805073402-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="3805073402-2">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3805073402-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">sum</span><span class="p" data-group-id="1529039755-3">(</span><span class="p" data-group-id="1529039755-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1529039755-4">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="1529039755-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="1529039755-5">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">H</span><span class="p" data-group-id="1529039755-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">sum</span><span class="p" data-group-id="1529039755-6">(</span><span class="p" data-group-id="1529039755-7">[</span><span class="p" data-group-id="1529039755-7">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="1529039755-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Sum</span><span class="p">.</span></code></pre>
│ │ │ │ +</span><span class="nf">sum</span><span class="p" data-group-id="3805073402-3">(</span><span class="p" data-group-id="3805073402-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3805073402-4">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="3805073402-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="3805073402-5">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">H</span><span class="p" data-group-id="3805073402-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">sum</span><span class="p" data-group-id="3805073402-6">(</span><span class="p" data-group-id="3805073402-7">[</span><span class="p" data-group-id="3805073402-7">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="3805073402-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Sum</span><span class="p">.</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/list_comprehensions.xhtml
│ │ │ │ @@ -22,33 +22,33 @@
│ │ │ │      </h1>
│ │ │ │  <h2 id="simple-examples" class="section-heading">
│ │ │ │    <a href="#simple-examples" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Simple Examples</span>
│ │ │ │  </h2>
│ │ │ │ -<p>This section starts with a simple example, showing a generator and a filter:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="1258810110-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="1258810110-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="1258810110-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1258810110-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1258810110-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="1258810110-3">]</span></code></pre><p>This is read as follows: The list of X such that X is taken from the list
│ │ │ │ +<p>This section starts with a simple example, showing a generator and a filter:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="5956936422-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5956936422-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5956936422-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="5956936422-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5956936422-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5956936422-3">]</span></code></pre><p>This is read as follows: The list of X such that X is taken from the list
│ │ │ │  <code class="inline">[1,2,a,...]</code> and X is greater than 3.</p><p>The notation <code class="inline">X &lt;- [1,2,a,...]</code> is a generator and the expression <code class="inline">X &gt; 3</code> is a
│ │ │ │  filter.</p><p>An additional filter, <a href="../../../lib/../erts/doc/html/erlang.html#is_integer/1"><code class="inline">is_integer(X)</code></a>, can be added to
│ │ │ │ -restrict the result to integers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="9187186880-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9187186880-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="9187186880-2">]</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="9187186880-3">(</span><span class="n">X</span><span class="p" data-group-id="9187186880-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="9187186880-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9187186880-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="9187186880-4">]</span></code></pre><p>Generators can be combined. For example, the Cartesian product of two lists can
│ │ │ │ -be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="7644826775-1">[</span><span class="p" data-group-id="7644826775-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7644826775-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="7644826775-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7644826775-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="7644826775-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7644826775-4">]</span><span class="p" data-group-id="7644826775-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7644826775-5">[</span><span class="p" data-group-id="7644826775-6">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="7644826775-6">}</span><span class="p">,</span><span class="p" data-group-id="7644826775-7">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7644826775-7">}</span><span class="p">,</span><span class="p" data-group-id="7644826775-8">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="7644826775-8">}</span><span class="p">,</span><span class="p" data-group-id="7644826775-9">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7644826775-9">}</span><span class="p">,</span><span class="p" data-group-id="7644826775-10">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="7644826775-10">}</span><span class="p">,</span><span class="p" data-group-id="7644826775-11">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7644826775-11">}</span><span class="p" data-group-id="7644826775-5">]</span></code></pre><h2 id="quick-sort" class="section-heading">
│ │ │ │ +restrict the result to integers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="5186173056-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5186173056-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5186173056-2">]</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="5186173056-3">(</span><span class="n">X</span><span class="p" data-group-id="5186173056-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="5186173056-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5186173056-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5186173056-4">]</span></code></pre><p>Generators can be combined. For example, the Cartesian product of two lists can
│ │ │ │ +be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="1024829636-1">[</span><span class="p" data-group-id="1024829636-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1024829636-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="1024829636-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1024829636-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="1024829636-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1024829636-4">]</span><span class="p" data-group-id="1024829636-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1024829636-5">[</span><span class="p" data-group-id="1024829636-6">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="1024829636-6">}</span><span class="p">,</span><span class="p" data-group-id="1024829636-7">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1024829636-7">}</span><span class="p">,</span><span class="p" data-group-id="1024829636-8">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="1024829636-8">}</span><span class="p">,</span><span class="p" data-group-id="1024829636-9">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1024829636-9">}</span><span class="p">,</span><span class="p" data-group-id="1024829636-10">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="1024829636-10">}</span><span class="p">,</span><span class="p" data-group-id="1024829636-11">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1024829636-11">}</span><span class="p" data-group-id="1024829636-5">]</span></code></pre><h2 id="quick-sort" class="section-heading">
│ │ │ │    <a href="#quick-sort" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Quick Sort</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The well-known quick sort routine can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sort</span><span class="p" data-group-id="2929172482-1">(</span><span class="p" data-group-id="2929172482-2">[</span><span class="p" data-group-id="2929172482-2">]</span><span class="p" data-group-id="2929172482-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2929172482-3">[</span><span class="p" data-group-id="2929172482-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">sort</span><span class="p" data-group-id="2929172482-4">(</span><span class="p" data-group-id="2929172482-5">[</span><span class="p">_</span><span class="p" data-group-id="2929172482-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="2929172482-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">L</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">sort</span><span class="p" data-group-id="2929172482-6">(</span><span class="p" data-group-id="2929172482-7">[</span><span class="n">Pivot</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2929172482-7">]</span><span class="p" data-group-id="2929172482-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">sort</span><span class="p" data-group-id="2929172482-8">(</span><span class="p" data-group-id="2929172482-9">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="2929172482-9">]</span><span class="p" data-group-id="2929172482-8">)</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2929172482-10">[</span><span class="n">Pivot</span><span class="p" data-group-id="2929172482-10">]</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ │ -    </span><span class="nf">sort</span><span class="p" data-group-id="2929172482-11">(</span><span class="p" data-group-id="2929172482-12">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="2929172482-12">]</span><span class="p" data-group-id="2929172482-11">)</span><span class="p">.</span></code></pre><p>The expression <code class="inline">[X || X &lt;- T, X &lt; Pivot]</code> is the list of all elements in <code class="inline">T</code>
│ │ │ │ +<p>The well-known quick sort routine can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sort</span><span class="p" data-group-id="1505923688-1">(</span><span class="p" data-group-id="1505923688-2">[</span><span class="p" data-group-id="1505923688-2">]</span><span class="p" data-group-id="1505923688-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1505923688-3">[</span><span class="p" data-group-id="1505923688-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">sort</span><span class="p" data-group-id="1505923688-4">(</span><span class="p" data-group-id="1505923688-5">[</span><span class="p">_</span><span class="p" data-group-id="1505923688-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="1505923688-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">L</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">sort</span><span class="p" data-group-id="1505923688-6">(</span><span class="p" data-group-id="1505923688-7">[</span><span class="n">Pivot</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1505923688-7">]</span><span class="p" data-group-id="1505923688-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">sort</span><span class="p" data-group-id="1505923688-8">(</span><span class="p" data-group-id="1505923688-9">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="1505923688-9">]</span><span class="p" data-group-id="1505923688-8">)</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1505923688-10">[</span><span class="n">Pivot</span><span class="p" data-group-id="1505923688-10">]</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ │ +    </span><span class="nf">sort</span><span class="p" data-group-id="1505923688-11">(</span><span class="p" data-group-id="1505923688-12">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="1505923688-12">]</span><span class="p" data-group-id="1505923688-11">)</span><span class="p">.</span></code></pre><p>The expression <code class="inline">[X || X &lt;- T, X &lt; Pivot]</code> is the list of all elements in <code class="inline">T</code>
│ │ │ │  that are less than <code class="inline">Pivot</code>.</p><p><code class="inline">[X || X &lt;- T, X &gt;= Pivot]</code> is the list of all elements in <code class="inline">T</code> that are greater
│ │ │ │  than or equal to <code class="inline">Pivot</code>.</p><p>With the algorithm above, a list is sorted as follows:</p><ul><li>A list with zero or one element is trivially sorted.</li><li>For lists with more than one element:<ol><li>The first element in the list is isolated as the pivot element.</li><li>The remaining list is partitioned into two sublists, such that:</li></ol><ul><li>The first sublist contains all elements that are smaller than the pivot
│ │ │ │  element.</li><li>The second sublist contains all elements that are greater than or equal to
│ │ │ │  the pivot element.</li></ul><ol><li>The sublists are recursively sorted by the same algorithm and the results
│ │ │ │  are combined, resulting in a list consisting of:</li></ol><ul><li>All elements from the first sublist, that is all elements smaller than the
│ │ │ │  pivot element, in sorted order.</li><li>The pivot element.</li><li>All elements from the second sublist, that is all elements greater than or
│ │ │ │  equal to the pivot element, in sorted order.</li></ul></li></ul><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>While the sorting algorithm as shown above serves as a nice example to
│ │ │ │ @@ -56,90 +56,90 @@
│ │ │ │  <a href="../../../lib/stdlib/doc/html/lists.html"><code class="inline">lists</code></a> module contains sorting functions that are implemented in a more
│ │ │ │  efficient way.</p></section><h2 id="permutations" class="section-heading">
│ │ │ │    <a href="#permutations" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Permutations</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The following example generates all permutations of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">perms</span><span class="p" data-group-id="2898062714-1">(</span><span class="p" data-group-id="2898062714-2">[</span><span class="p" data-group-id="2898062714-2">]</span><span class="p" data-group-id="2898062714-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2898062714-3">[</span><span class="p" data-group-id="2898062714-4">[</span><span class="p" data-group-id="2898062714-4">]</span><span class="p" data-group-id="2898062714-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">perms</span><span class="p" data-group-id="2898062714-5">(</span><span class="n">L</span><span class="p" data-group-id="2898062714-5">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2898062714-6">[</span><span class="p" data-group-id="2898062714-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2898062714-7">]</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">H</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nf">perms</span><span class="p" data-group-id="2898062714-8">(</span><span class="n">L</span><span class="o">--</span><span class="p" data-group-id="2898062714-9">[</span><span class="n">H</span><span class="p" data-group-id="2898062714-9">]</span><span class="p" data-group-id="2898062714-8">)</span><span class="p" data-group-id="2898062714-6">]</span><span class="p">.</span></code></pre><p>This takes <code class="inline">H</code> from <code class="inline">L</code> in all possible ways. The result is the set of all lists
│ │ │ │ +<p>The following example generates all permutations of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">perms</span><span class="p" data-group-id="5044032095-1">(</span><span class="p" data-group-id="5044032095-2">[</span><span class="p" data-group-id="5044032095-2">]</span><span class="p" data-group-id="5044032095-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5044032095-3">[</span><span class="p" data-group-id="5044032095-4">[</span><span class="p" data-group-id="5044032095-4">]</span><span class="p" data-group-id="5044032095-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">perms</span><span class="p" data-group-id="5044032095-5">(</span><span class="n">L</span><span class="p" data-group-id="5044032095-5">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5044032095-6">[</span><span class="p" data-group-id="5044032095-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5044032095-7">]</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">H</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nf">perms</span><span class="p" data-group-id="5044032095-8">(</span><span class="n">L</span><span class="o">--</span><span class="p" data-group-id="5044032095-9">[</span><span class="n">H</span><span class="p" data-group-id="5044032095-9">]</span><span class="p" data-group-id="5044032095-8">)</span><span class="p" data-group-id="5044032095-6">]</span><span class="p">.</span></code></pre><p>This takes <code class="inline">H</code> from <code class="inline">L</code> in all possible ways. The result is the set of all lists
│ │ │ │  <code class="inline">[H|T]</code>, where <code class="inline">T</code> is the set of all possible permutations of <code class="inline">L</code>, with <code class="inline">H</code>
│ │ │ │ -removed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">perms</span><span class="p" data-group-id="5540084995-1">(</span><span class="p" data-group-id="5540084995-2">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5540084995-2">]</span><span class="p" data-group-id="5540084995-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5540084995-3">[</span><span class="p" data-group-id="5540084995-4">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5540084995-4">]</span><span class="p">,</span><span class="p" data-group-id="5540084995-5">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="5540084995-5">]</span><span class="p">,</span><span class="p" data-group-id="5540084995-6">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5540084995-6">]</span><span class="p">,</span><span class="p" data-group-id="5540084995-7">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5540084995-7">]</span><span class="p">,</span><span class="p" data-group-id="5540084995-8">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="5540084995-8">]</span><span class="p">,</span><span class="p" data-group-id="5540084995-9">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5540084995-9">]</span><span class="p" data-group-id="5540084995-3">]</span></code></pre><h2 id="pythagorean-triplets" class="section-heading">
│ │ │ │ +removed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">perms</span><span class="p" data-group-id="5610696071-1">(</span><span class="p" data-group-id="5610696071-2">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5610696071-2">]</span><span class="p" data-group-id="5610696071-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5610696071-3">[</span><span class="p" data-group-id="5610696071-4">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5610696071-4">]</span><span class="p">,</span><span class="p" data-group-id="5610696071-5">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="5610696071-5">]</span><span class="p">,</span><span class="p" data-group-id="5610696071-6">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5610696071-6">]</span><span class="p">,</span><span class="p" data-group-id="5610696071-7">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5610696071-7">]</span><span class="p">,</span><span class="p" data-group-id="5610696071-8">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="5610696071-8">]</span><span class="p">,</span><span class="p" data-group-id="5610696071-9">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5610696071-9">]</span><span class="p" data-group-id="5610696071-3">]</span></code></pre><h2 id="pythagorean-triplets" class="section-heading">
│ │ │ │    <a href="#pythagorean-triplets" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Pythagorean Triplets</span>
│ │ │ │  </h2>
│ │ │ │  <p>Pythagorean triplets are sets of integers <code class="inline">{A,B,C}</code> such that
│ │ │ │  <code class="inline">A**2 + B**2 = C**2</code>.</p><p>The function <code class="inline">pyth(N)</code> generates a list of all integers <code class="inline">{A,B,C}</code> such that
│ │ │ │  <code class="inline">A**2 + B**2 = C**2</code> and where the sum of the sides is equal to, or less than,
│ │ │ │ -<code class="inline">N</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth</span><span class="p" data-group-id="0275760113-1">(</span><span class="n">N</span><span class="p" data-group-id="0275760113-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0275760113-2">[</span><span class="w"> </span><span class="p" data-group-id="0275760113-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="0275760113-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ │ -        </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0275760113-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0275760113-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0275760113-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0275760113-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0275760113-6">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0275760113-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +<code class="inline">N</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth</span><span class="p" data-group-id="9624886265-1">(</span><span class="n">N</span><span class="p" data-group-id="9624886265-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9624886265-2">[</span><span class="w"> </span><span class="p" data-group-id="9624886265-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="9624886265-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ │ +        </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9624886265-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="9624886265-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9624886265-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="9624886265-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9624886265-6">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="9624886265-6">)</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">+</span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="n">A</span><span class="o">*</span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">*</span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">C</span><span class="o">*</span><span class="n">C</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0275760113-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="6565578654-1">(</span><span class="mi">3</span><span class="p" data-group-id="6565578654-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6565578654-2">[</span><span class="p" data-group-id="6565578654-2">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="6565578654-3">(</span><span class="mi">11</span><span class="p" data-group-id="6565578654-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6565578654-4">[</span><span class="p" data-group-id="6565578654-4">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="6565578654-5">(</span><span class="mi">12</span><span class="p" data-group-id="6565578654-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6565578654-6">[</span><span class="p" data-group-id="6565578654-7">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6565578654-7">}</span><span class="p">,</span><span class="p" data-group-id="6565578654-8">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6565578654-8">}</span><span class="p" data-group-id="6565578654-6">]</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="6565578654-9">(</span><span class="mi">50</span><span class="p" data-group-id="6565578654-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6565578654-10">[</span><span class="p" data-group-id="6565578654-11">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6565578654-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-12">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6565578654-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-13">{</span><span class="mi">5</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="6565578654-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-14">{</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="6565578654-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-15">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="6565578654-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-16">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="6565578654-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-17">{</span><span class="mi">9</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="6565578654-17">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-18">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="6565578654-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-19">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="6565578654-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-20">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="6565578654-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-21">{</span><span class="mi">15</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="6565578654-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="6565578654-22">{</span><span class="mi">16</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="6565578654-22">}</span><span class="p" data-group-id="6565578654-10">]</span></code></pre><p>The following code reduces the search space and is more efficient:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth1</span><span class="p" data-group-id="2656300478-1">(</span><span class="n">N</span><span class="p" data-group-id="2656300478-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="2656300478-2">[</span><span class="p" data-group-id="2656300478-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="2656300478-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ │ -       </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2656300478-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="2656300478-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -       </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2656300478-5">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="2656300478-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -       </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2656300478-6">(</span><span class="n">B</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="2656300478-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9624886265-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="4317220490-1">(</span><span class="mi">3</span><span class="p" data-group-id="4317220490-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4317220490-2">[</span><span class="p" data-group-id="4317220490-2">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="4317220490-3">(</span><span class="mi">11</span><span class="p" data-group-id="4317220490-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4317220490-4">[</span><span class="p" data-group-id="4317220490-4">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="4317220490-5">(</span><span class="mi">12</span><span class="p" data-group-id="4317220490-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4317220490-6">[</span><span class="p" data-group-id="4317220490-7">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4317220490-7">}</span><span class="p">,</span><span class="p" data-group-id="4317220490-8">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4317220490-8">}</span><span class="p" data-group-id="4317220490-6">]</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="4317220490-9">(</span><span class="mi">50</span><span class="p" data-group-id="4317220490-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4317220490-10">[</span><span class="p" data-group-id="4317220490-11">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4317220490-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-12">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4317220490-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-13">{</span><span class="mi">5</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="4317220490-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-14">{</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="4317220490-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-15">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="4317220490-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-16">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="4317220490-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-17">{</span><span class="mi">9</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="4317220490-17">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-18">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="4317220490-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-19">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="4317220490-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-20">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="4317220490-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-21">{</span><span class="mi">15</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="4317220490-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4317220490-22">{</span><span class="mi">16</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="4317220490-22">}</span><span class="p" data-group-id="4317220490-10">]</span></code></pre><p>The following code reduces the search space and is more efficient:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth1</span><span class="p" data-group-id="2333955642-1">(</span><span class="n">N</span><span class="p" data-group-id="2333955642-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="2333955642-2">[</span><span class="p" data-group-id="2333955642-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="2333955642-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ │ +       </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2333955642-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="2333955642-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +       </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2333955642-5">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="2333955642-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +       </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2333955642-6">(</span><span class="n">B</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="2333955642-6">)</span><span class="p">,</span><span class="w">
│ │ │ │         </span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">+</span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w">
│ │ │ │ -       </span><span class="n">A</span><span class="o">*</span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">*</span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">C</span><span class="o">*</span><span class="n">C</span><span class="w"> </span><span class="p" data-group-id="2656300478-2">]</span><span class="p">.</span></code></pre><h2 id="simplifications-with-list-comprehensions" class="section-heading">
│ │ │ │ +       </span><span class="n">A</span><span class="o">*</span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">*</span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">C</span><span class="o">*</span><span class="n">C</span><span class="w"> </span><span class="p" data-group-id="2333955642-2">]</span><span class="p">.</span></code></pre><h2 id="simplifications-with-list-comprehensions" class="section-heading">
│ │ │ │    <a href="#simplifications-with-list-comprehensions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Simplifications With List Comprehensions</span>
│ │ │ │  </h2>
│ │ │ │  <p>As an example, list comprehensions can be used to simplify some of the functions
│ │ │ │ -in <code class="inline">lists.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="4253349081-1">(</span><span class="n">L</span><span class="p" data-group-id="4253349081-1">)</span><span class="w">   </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="4253349081-2">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">L1</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="4253349081-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="4253349081-3">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4253349081-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4253349081-4">[</span><span class="n">Fun</span><span class="p" data-group-id="4253349081-5">(</span><span class="n">X</span><span class="p" data-group-id="4253349081-5">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4253349081-4">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">filter</span><span class="p" data-group-id="4253349081-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4253349081-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4253349081-7">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="4253349081-8">(</span><span class="n">X</span><span class="p" data-group-id="4253349081-8">)</span><span class="p" data-group-id="4253349081-7">]</span><span class="p">.</span></code></pre><h2 id="variable-bindings-in-list-comprehensions" class="section-heading">
│ │ │ │ +in <code class="inline">lists.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="5097886008-1">(</span><span class="n">L</span><span class="p" data-group-id="5097886008-1">)</span><span class="w">   </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="5097886008-2">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">L1</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="5097886008-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="5097886008-3">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5097886008-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5097886008-4">[</span><span class="n">Fun</span><span class="p" data-group-id="5097886008-5">(</span><span class="n">X</span><span class="p" data-group-id="5097886008-5">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5097886008-4">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">filter</span><span class="p" data-group-id="5097886008-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5097886008-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5097886008-7">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="5097886008-8">(</span><span class="n">X</span><span class="p" data-group-id="5097886008-8">)</span><span class="p" data-group-id="5097886008-7">]</span><span class="p">.</span></code></pre><h2 id="variable-bindings-in-list-comprehensions" class="section-heading">
│ │ │ │    <a href="#variable-bindings-in-list-comprehensions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Variable Bindings in List Comprehensions</span>
│ │ │ │  </h2>
│ │ │ │  <p>The scope rules for variables that occur in list comprehensions are as follows:</p><ul><li>All variables that occur in a generator pattern are assumed to be &quot;fresh&quot;
│ │ │ │  variables.</li><li>Any variables that are defined before the list comprehension, and that are
│ │ │ │  used in filters, have the values they had before the list comprehension.</li><li>Variables cannot be exported from a list comprehension.</li></ul><p>As an example of these rules, suppose you want to write the function <code class="inline">select</code>,
│ │ │ │  which selects certain elements from a list of tuples. Suppose you write
│ │ │ │  <code class="inline">select(X, L) -&gt; [Y || {X, Y} &lt;- L].</code> with the intention of extracting all
│ │ │ │  tuples from <code class="inline">L</code>, where the first item is <code class="inline">X</code>.</p><p>Compiling this gives the following diagnostic:</p><pre><code class="text">./FileName.erl:Line: Warning: variable 'X' shadowed in generate</code></pre><p>This diagnostic warns that the variable <code class="inline">X</code> in the pattern is not the same as
│ │ │ │ -the variable <code class="inline">X</code> that occurs in the function head.</p><p>Evaluating <code class="inline">select</code> gives the following result:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="1289356416-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="1289356416-2">[</span><span class="p" data-group-id="1289356416-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="1289356416-3">}</span><span class="p">,</span><span class="p" data-group-id="1289356416-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1289356416-4">}</span><span class="p">,</span><span class="p" data-group-id="1289356416-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1289356416-5">}</span><span class="p">,</span><span class="p" data-group-id="1289356416-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="1289356416-6">}</span><span class="p" data-group-id="1289356416-2">]</span><span class="p" data-group-id="1289356416-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1289356416-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="1289356416-7">]</span></code></pre><p>This is not the wanted result. To achieve the desired effect, <code class="inline">select</code> must be
│ │ │ │ -written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">select</span><span class="p" data-group-id="9567889442-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="9567889442-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="9567889442-2">[</span><span class="n">Y</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="9567889442-3">{</span><span class="n">X1</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9567889442-3">}</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">X1</span><span class="p" data-group-id="9567889442-2">]</span><span class="p">.</span></code></pre><p>The generator now contains unbound variables and the test has been moved into
│ │ │ │ -the filter.</p><p>This now works as expected:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="1459171670-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="1459171670-2">[</span><span class="p" data-group-id="1459171670-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="1459171670-3">}</span><span class="p">,</span><span class="p" data-group-id="1459171670-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1459171670-4">}</span><span class="p">,</span><span class="p" data-group-id="1459171670-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1459171670-5">}</span><span class="p">,</span><span class="p" data-group-id="1459171670-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="1459171670-6">}</span><span class="p" data-group-id="1459171670-2">]</span><span class="p" data-group-id="1459171670-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1459171670-7">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="1459171670-7">]</span></code></pre><p>Also note that a variable in a generator pattern will shadow a variable with the
│ │ │ │ -same name bound in a previous generator pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="3019867970-1">[</span><span class="p" data-group-id="3019867970-2">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p" data-group-id="3019867970-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="3019867970-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3019867970-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="o">=</span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="3019867970-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3019867970-4">]</span><span class="p" data-group-id="3019867970-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3019867970-5">[</span><span class="p" data-group-id="3019867970-6">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3019867970-6">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-7">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3019867970-7">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-8">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3019867970-8">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3019867970-9">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3019867970-10">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-11">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3019867970-11">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-12">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3019867970-12">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-13">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3019867970-13">}</span><span class="p">,</span><span class="p" data-group-id="3019867970-14">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3019867970-14">}</span><span class="p" data-group-id="3019867970-5">]</span></code></pre><p>A consequence of the rules for importing variables into a list comprehensions is
│ │ │ │ +the variable <code class="inline">X</code> that occurs in the function head.</p><p>Evaluating <code class="inline">select</code> gives the following result:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="9680487964-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="9680487964-2">[</span><span class="p" data-group-id="9680487964-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9680487964-3">}</span><span class="p">,</span><span class="p" data-group-id="9680487964-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9680487964-4">}</span><span class="p">,</span><span class="p" data-group-id="9680487964-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9680487964-5">}</span><span class="p">,</span><span class="p" data-group-id="9680487964-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9680487964-6">}</span><span class="p" data-group-id="9680487964-2">]</span><span class="p" data-group-id="9680487964-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9680487964-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9680487964-7">]</span></code></pre><p>This is not the wanted result. To achieve the desired effect, <code class="inline">select</code> must be
│ │ │ │ +written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">select</span><span class="p" data-group-id="6599253234-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6599253234-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="6599253234-2">[</span><span class="n">Y</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="6599253234-3">{</span><span class="n">X1</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6599253234-3">}</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">X1</span><span class="p" data-group-id="6599253234-2">]</span><span class="p">.</span></code></pre><p>The generator now contains unbound variables and the test has been moved into
│ │ │ │ +the filter.</p><p>This now works as expected:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="9500216287-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="9500216287-2">[</span><span class="p" data-group-id="9500216287-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9500216287-3">}</span><span class="p">,</span><span class="p" data-group-id="9500216287-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9500216287-4">}</span><span class="p">,</span><span class="p" data-group-id="9500216287-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9500216287-5">}</span><span class="p">,</span><span class="p" data-group-id="9500216287-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9500216287-6">}</span><span class="p" data-group-id="9500216287-2">]</span><span class="p" data-group-id="9500216287-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9500216287-7">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9500216287-7">]</span></code></pre><p>Also note that a variable in a generator pattern will shadow a variable with the
│ │ │ │ +same name bound in a previous generator pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="0680724154-1">[</span><span class="p" data-group-id="0680724154-2">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p" data-group-id="0680724154-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="0680724154-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0680724154-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="o">=</span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="0680724154-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0680724154-4">]</span><span class="p" data-group-id="0680724154-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0680724154-5">[</span><span class="p" data-group-id="0680724154-6">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="0680724154-6">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-7">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0680724154-7">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-8">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0680724154-8">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="0680724154-9">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0680724154-10">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-11">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0680724154-11">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-12">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="0680724154-12">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-13">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0680724154-13">}</span><span class="p">,</span><span class="p" data-group-id="0680724154-14">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0680724154-14">}</span><span class="p" data-group-id="0680724154-5">]</span></code></pre><p>A consequence of the rules for importing variables into a list comprehensions is
│ │ │ │  that certain pattern matching operations must be moved into the filters and
│ │ │ │ -cannot be written directly in the generators.</p><p>To illustrate this, do <em>not</em> write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="8091038473-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="8091038473-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +cannot be written directly in the generators.</p><p>To illustrate this, do <em>not</em> write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="3270728967-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3270728967-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8091038473-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="8091038473-2">]</span><span class="w">
│ │ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Instead, write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="6020429249-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6020429249-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3270728967-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3270728967-2">]</span><span class="w">
│ │ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Instead, write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="3397030125-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3397030125-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6020429249-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y1</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6020429249-2">]</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3397030125-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y1</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3397030125-2">]</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/install-win32.xhtml
│ │ │ │ @@ -200,15 +200,15 @@
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">cd erts/emulator
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">make debug
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">cd ../etc
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">make debug
│ │ │ │  </span></code></pre><p>and sometimes</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">make local_setup
│ │ │ │  </span></code></pre><p>So now when you run <code class="inline">$ERL_TOP/erl.exe</code>, you should have a debug compiled
│ │ │ │ -emulator, which you will see if you do a:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="3496661123-1">(</span><span class="ss">system_version</span><span class="p" data-group-id="3496661123-1">)</span><span class="p">.</span></code></pre><p>in the erlang shell. If the returned string contains <code class="inline">[debug]</code>, you
│ │ │ │ +emulator, which you will see if you do a:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="9382226587-1">(</span><span class="ss">system_version</span><span class="p" data-group-id="9382226587-1">)</span><span class="p">.</span></code></pre><p>in the erlang shell. If the returned string contains <code class="inline">[debug]</code>, you
│ │ │ │  got a debug compiled emulator.</p><p>To hack the erlang libraries, you simply do a <code class="inline">make opt</code> in the
│ │ │ │  specific &quot;applications&quot; directory, like:</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP/lib/stdlib
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">make opt
│ │ │ │  </span></code></pre><p>or even in the source directory...</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP/lib/stdlib/src
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">make opt
│ │ │ │  </span></code></pre><p>Note that you're expected to have a fresh Erlang in your path when
│ │ │ │  doing this, preferably the plain 27 you have built in the previous
│ │ │ │ @@ -223,19 +223,19 @@
│ │ │ │  </span><span class="">:$ERL_TOP/erts/etc/win32/wsl_tools:$ERL_TOP/bootstrap/bin:$PATH
│ │ │ │  </span></code></pre><p>That should make it possible to rebuild any library without hassle...</p><p>If you want to copy a library (an application) newly built, to a
│ │ │ │  release area, you do like with the emulator:</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP/lib/stdlib
│ │ │ │  </span><span class="gp unselectable">$ </span><span class="">make TESTROOT=/tmp/erlang_release release
│ │ │ │  </span></code></pre><p>Remember that:</p><ul><li><p>  Windows specific C-code goes in the <code class="inline">$ERL_TOP/erts/emulator/sys/win32</code>,
│ │ │ │  <code class="inline">$ERL_TOP/erts/emulator/drivers/win32</code> or <code class="inline">$ERL_TOP/erts/etc/win32</code>.</p></li><li><p>  Windows specific erlang code should be used conditionally and the
│ │ │ │  host OS tested in <em>runtime</em>, the exactly same beam files should be
│ │ │ │ -distributed for every platform! So write code like:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">os</span><span class="p">:</span><span class="nf">type</span><span class="p" data-group-id="2979279341-1">(</span><span class="p" data-group-id="2979279341-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2979279341-2">{</span><span class="ss">win32</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="2979279341-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nf">do_windows_specific</span><span class="p" data-group-id="2979279341-3">(</span><span class="p" data-group-id="2979279341-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +distributed for every platform! So write code like:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">os</span><span class="p">:</span><span class="nf">type</span><span class="p" data-group-id="3849364885-1">(</span><span class="p" data-group-id="3849364885-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3849364885-2">{</span><span class="ss">win32</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="3849364885-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nf">do_windows_specific</span><span class="p" data-group-id="3849364885-3">(</span><span class="p" data-group-id="3849364885-3">)</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="n">Other</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nf">do_fallback_or_exit</span><span class="p" data-group-id="2979279341-4">(</span><span class="p" data-group-id="2979279341-4">)</span><span class="w">
│ │ │ │ +        </span><span class="nf">do_fallback_or_exit</span><span class="p" data-group-id="3849364885-4">(</span><span class="p" data-group-id="3849364885-4">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">,</span></code></pre></li></ul><p>That's basically all you need to get going.</p><h2 id="frequently-asked-questions" class="section-heading">
│ │ │ │    <a href="#frequently-asked-questions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Frequently Asked Questions</span>
│ │ │ │  </h2>
│ │ │ │  <ul><li><p>  Q: So, now I can build Erlang using GCC on Windows?</p><p>A: No, unfortunately not. You'll need Microsoft's Visual C++
│ │ │ ├── OEBPS/included_applications.xhtml
│ │ │ │ @@ -66,72 +66,72 @@
│ │ │ │  belonging to the primary application.</p><h2 id="specifying-included-applications" class="section-heading">
│ │ │ │    <a href="#specifying-included-applications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Specifying Included Applications</span>
│ │ │ │  </h2>
│ │ │ │  <p>Which applications to include is defined by the <code class="inline">included_applications</code> key in
│ │ │ │ -the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9557750365-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="9557750365-2">[</span><span class="p" data-group-id="9557750365-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="9557750365-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="9557750365-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="9557750365-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="9557750365-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557750365-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="9557750365-6">]</span><span class="p" data-group-id="9557750365-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="9557750365-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557750365-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="9557750365-8">]</span><span class="p" data-group-id="9557750365-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="9557750365-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557750365-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="9557750365-10">]</span><span class="p" data-group-id="9557750365-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="9557750365-11">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557750365-12">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="9557750365-12">]</span><span class="p" data-group-id="9557750365-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="9557750365-13">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557750365-14">{</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="9557750365-15">[</span><span class="p" data-group-id="9557750365-15">]</span><span class="p" data-group-id="9557750365-14">}</span><span class="p" data-group-id="9557750365-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="9557750365-16">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557750365-17">[</span><span class="p" data-group-id="9557750365-18">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="9557750365-18">}</span><span class="p" data-group-id="9557750365-17">]</span><span class="p" data-group-id="9557750365-16">}</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="9557750365-2">]</span><span class="p" data-group-id="9557750365-1">}</span><span class="p">.</span></code></pre><h2 id="synchronizing-processes-during-startup" class="section-heading">
│ │ │ │ +the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6809231477-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="6809231477-2">[</span><span class="p" data-group-id="6809231477-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="6809231477-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6809231477-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="6809231477-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6809231477-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6809231477-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="6809231477-6">]</span><span class="p" data-group-id="6809231477-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6809231477-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6809231477-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="6809231477-8">]</span><span class="p" data-group-id="6809231477-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6809231477-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6809231477-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="6809231477-10">]</span><span class="p" data-group-id="6809231477-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6809231477-11">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6809231477-12">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="6809231477-12">]</span><span class="p" data-group-id="6809231477-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6809231477-13">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6809231477-14">{</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="6809231477-15">[</span><span class="p" data-group-id="6809231477-15">]</span><span class="p" data-group-id="6809231477-14">}</span><span class="p" data-group-id="6809231477-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6809231477-16">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6809231477-17">[</span><span class="p" data-group-id="6809231477-18">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="6809231477-18">}</span><span class="p" data-group-id="6809231477-17">]</span><span class="p" data-group-id="6809231477-16">}</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="6809231477-2">]</span><span class="p" data-group-id="6809231477-1">}</span><span class="p">.</span></code></pre><h2 id="synchronizing-processes-during-startup" class="section-heading">
│ │ │ │    <a href="#synchronizing-processes-during-startup" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Synchronizing Processes during Startup</span>
│ │ │ │  </h2>
│ │ │ │  <p>The supervisor tree of an included application is started as part of the
│ │ │ │  supervisor tree of the including application. If there is a need for
│ │ │ │  synchronization between processes in the including and included applications,
│ │ │ │  this can be achieved by using <em>start phases</em>.</p><p>Start phases are defined by the <code class="inline">start_phases</code> key in the <code class="inline">.app</code> file as a list
│ │ │ │  of tuples <code class="inline">{Phase,PhaseArgs}</code>, where <code class="inline">Phase</code> is an atom and <code class="inline">PhaseArgs</code> is a
│ │ │ │  term.</p><p>The value of the <code class="inline">mod</code> key of the including application must be set to
│ │ │ │  <code class="inline">{application_starter,[Module,StartArgs]}</code>, where <code class="inline">Module</code> as usual is the
│ │ │ │  application callback module. <code class="inline">StartArgs</code> is a term provided as argument to the
│ │ │ │ -callback function <code class="inline">Module:start/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4195164171-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4195164171-2">[</span><span class="p" data-group-id="4195164171-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="4195164171-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4195164171-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="4195164171-6">]</span><span class="p" data-group-id="4195164171-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="4195164171-8">]</span><span class="p" data-group-id="4195164171-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="4195164171-10">]</span><span class="p" data-group-id="4195164171-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-11">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-12">[</span><span class="p" data-group-id="4195164171-13">{</span><span class="ss">init</span><span class="p">,</span><span class="p" data-group-id="4195164171-14">[</span><span class="p" data-group-id="4195164171-14">]</span><span class="p" data-group-id="4195164171-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-15">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="4195164171-16">[</span><span class="p" data-group-id="4195164171-16">]</span><span class="p" data-group-id="4195164171-15">}</span><span class="p" data-group-id="4195164171-12">]</span><span class="p" data-group-id="4195164171-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-17">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-18">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="4195164171-18">]</span><span class="p" data-group-id="4195164171-17">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-19">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-20">{</span><span class="ss">application_starter</span><span class="p">,</span><span class="p" data-group-id="4195164171-21">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="4195164171-22">[</span><span class="p" data-group-id="4195164171-22">]</span><span class="p" data-group-id="4195164171-21">]</span><span class="p" data-group-id="4195164171-20">}</span><span class="p" data-group-id="4195164171-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-23">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-24">[</span><span class="p" data-group-id="4195164171-25">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="4195164171-25">}</span><span class="p" data-group-id="4195164171-24">]</span><span class="p" data-group-id="4195164171-23">}</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4195164171-2">]</span><span class="p" data-group-id="4195164171-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +callback function <code class="inline">Module:start/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9284605765-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9284605765-2">[</span><span class="p" data-group-id="9284605765-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="9284605765-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="9284605765-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="9284605765-6">]</span><span class="p" data-group-id="9284605765-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="9284605765-8">]</span><span class="p" data-group-id="9284605765-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="9284605765-10">]</span><span class="p" data-group-id="9284605765-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-11">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-12">[</span><span class="p" data-group-id="9284605765-13">{</span><span class="ss">init</span><span class="p">,</span><span class="p" data-group-id="9284605765-14">[</span><span class="p" data-group-id="9284605765-14">]</span><span class="p" data-group-id="9284605765-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-15">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="9284605765-16">[</span><span class="p" data-group-id="9284605765-16">]</span><span class="p" data-group-id="9284605765-15">}</span><span class="p" data-group-id="9284605765-12">]</span><span class="p" data-group-id="9284605765-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-17">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-18">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="9284605765-18">]</span><span class="p" data-group-id="9284605765-17">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-19">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-20">{</span><span class="ss">application_starter</span><span class="p">,</span><span class="p" data-group-id="9284605765-21">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="9284605765-22">[</span><span class="p" data-group-id="9284605765-22">]</span><span class="p" data-group-id="9284605765-21">]</span><span class="p" data-group-id="9284605765-20">}</span><span class="p" data-group-id="9284605765-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-23">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-24">[</span><span class="p" data-group-id="9284605765-25">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="9284605765-25">}</span><span class="p" data-group-id="9284605765-24">]</span><span class="p" data-group-id="9284605765-23">}</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9284605765-2">]</span><span class="p" data-group-id="9284605765-1">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="p" data-group-id="4195164171-26">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4195164171-27">[</span><span class="p" data-group-id="4195164171-28">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Included application&quot;</span><span class="p" data-group-id="4195164171-28">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-29">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4195164171-29">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-30">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-31">[</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_server</span><span class="p" data-group-id="4195164171-31">]</span><span class="p" data-group-id="4195164171-30">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-32">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-33">[</span><span class="p" data-group-id="4195164171-33">]</span><span class="p" data-group-id="4195164171-32">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-34">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-35">[</span><span class="p" data-group-id="4195164171-36">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="4195164171-37">[</span><span class="p" data-group-id="4195164171-37">]</span><span class="p" data-group-id="4195164171-36">}</span><span class="p" data-group-id="4195164171-35">]</span><span class="p" data-group-id="4195164171-34">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-38">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-39">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="4195164171-39">]</span><span class="p" data-group-id="4195164171-38">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4195164171-40">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4195164171-41">{</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="p" data-group-id="4195164171-42">[</span><span class="p" data-group-id="4195164171-42">]</span><span class="p" data-group-id="4195164171-41">}</span><span class="p" data-group-id="4195164171-40">}</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4195164171-27">]</span><span class="p" data-group-id="4195164171-26">}</span><span class="p">.</span></code></pre><p>When starting a primary application with included applications, the primary
│ │ │ │ +</span><span class="p" data-group-id="9284605765-26">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9284605765-27">[</span><span class="p" data-group-id="9284605765-28">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Included application&quot;</span><span class="p" data-group-id="9284605765-28">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-29">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="9284605765-29">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-30">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-31">[</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_server</span><span class="p" data-group-id="9284605765-31">]</span><span class="p" data-group-id="9284605765-30">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-32">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-33">[</span><span class="p" data-group-id="9284605765-33">]</span><span class="p" data-group-id="9284605765-32">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-34">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-35">[</span><span class="p" data-group-id="9284605765-36">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="9284605765-37">[</span><span class="p" data-group-id="9284605765-37">]</span><span class="p" data-group-id="9284605765-36">}</span><span class="p" data-group-id="9284605765-35">]</span><span class="p" data-group-id="9284605765-34">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-38">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-39">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="9284605765-39">]</span><span class="p" data-group-id="9284605765-38">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9284605765-40">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9284605765-41">{</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="p" data-group-id="9284605765-42">[</span><span class="p" data-group-id="9284605765-42">]</span><span class="p" data-group-id="9284605765-41">}</span><span class="p" data-group-id="9284605765-40">}</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9284605765-27">]</span><span class="p" data-group-id="9284605765-26">}</span><span class="p">.</span></code></pre><p>When starting a primary application with included applications, the primary
│ │ │ │  application is started the normal way, that is:</p><ul><li>The application controller creates an application master for the application</li><li>The application master calls <code class="inline">Module:start(normal, StartArgs)</code> to start the
│ │ │ │  top supervisor.</li></ul><p>Then, for the primary application and each included application in top-down,
│ │ │ │  left-to-right order, the application master calls
│ │ │ │  <code class="inline">Module:start_phase(Phase, Type, PhaseArgs)</code> for each phase defined for the
│ │ │ │  primary application, in that order. If a phase is not defined for an included
│ │ │ │  application, the function is not called for this phase and application.</p><p>The following requirements apply to the <code class="inline">.app</code> file for an included application:</p><ul><li>The <code class="inline">{mod, {Module,StartArgs}}</code> option must be included. This option is used
│ │ │ │  to find the callback module <code class="inline">Module</code> of the application. <code class="inline">StartArgs</code> is
│ │ │ │  ignored, as <code class="inline">Module:start/2</code> is called only for the primary application.</li><li>If the included application itself contains included applications, instead the
│ │ │ │  <code class="inline">{mod, {application_starter, [Module,StartArgs]}}</code> option must be included.</li><li>The <code class="inline">{start_phases, [{Phase,PhaseArgs}]}</code> option must be included, and the set
│ │ │ │  of specified phases must be a subset of the set of phases specified for the
│ │ │ │  primary application.</li></ul><p>When starting <code class="inline">prim_app</code> as defined above, the application controller calls the
│ │ │ │  following callback functions before <code class="inline">application:start(prim_app)</code> returns a
│ │ │ │ -value:</p><pre><code class="makeup erlang" translate="no"><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="6347410261-1">(</span><span class="ss">prim_app</span><span class="p" data-group-id="6347410261-1">)</span><span class="w">
│ │ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="6347410261-2">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6347410261-3">[</span><span class="p" data-group-id="6347410261-3">]</span><span class="p" data-group-id="6347410261-2">)</span><span class="w">
│ │ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="6347410261-4">(</span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6347410261-5">[</span><span class="p" data-group-id="6347410261-5">]</span><span class="p" data-group-id="6347410261-4">)</span><span class="w">
│ │ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="6347410261-6">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6347410261-7">[</span><span class="p" data-group-id="6347410261-7">]</span><span class="p" data-group-id="6347410261-6">)</span><span class="w">
│ │ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">incl_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="6347410261-8">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6347410261-9">[</span><span class="p" data-group-id="6347410261-9">]</span><span class="p" data-group-id="6347410261-8">)</span><span class="w">
│ │ │ │ +value:</p><pre><code class="makeup erlang" translate="no"><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5780523075-1">(</span><span class="ss">prim_app</span><span class="p" data-group-id="5780523075-1">)</span><span class="w">
│ │ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5780523075-2">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5780523075-3">[</span><span class="p" data-group-id="5780523075-3">]</span><span class="p" data-group-id="5780523075-2">)</span><span class="w">
│ │ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="5780523075-4">(</span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5780523075-5">[</span><span class="p" data-group-id="5780523075-5">]</span><span class="p" data-group-id="5780523075-4">)</span><span class="w">
│ │ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="5780523075-6">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5780523075-7">[</span><span class="p" data-group-id="5780523075-7">]</span><span class="p" data-group-id="5780523075-6">)</span><span class="w">
│ │ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">incl_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="5780523075-8">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5780523075-9">[</span><span class="p" data-group-id="5780523075-9">]</span><span class="p" data-group-id="5780523075-8">)</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/gen_server_concepts.xhtml
│ │ │ │ @@ -62,63 +62,63 @@
│ │ │ │    <a href="#example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Example</span>
│ │ │ │  </h2>
│ │ │ │  <p>An example of a simple server written in plain Erlang is provided in
│ │ │ │  <a href="design_principles.xhtml#ch1">Overview</a>. The server can be reimplemented using
│ │ │ │ -<code class="inline">gen_server</code>, resulting in this callback module:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1727359945-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="1727359945-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="1727359945-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="1727359945-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">gen_server</code>, resulting in this callback module:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0385045966-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="0385045966-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="0385045966-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="0385045966-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1727359945-3">(</span><span class="p" data-group-id="1727359945-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1727359945-4">]</span><span class="p" data-group-id="1727359945-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1727359945-5">(</span><span class="p" data-group-id="1727359945-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1727359945-6">]</span><span class="p" data-group-id="1727359945-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1727359945-7">(</span><span class="p" data-group-id="1727359945-8">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1727359945-8">]</span><span class="p" data-group-id="1727359945-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0385045966-3">(</span><span class="p" data-group-id="0385045966-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0385045966-4">]</span><span class="p" data-group-id="0385045966-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0385045966-5">(</span><span class="p" data-group-id="0385045966-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0385045966-6">]</span><span class="p" data-group-id="0385045966-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0385045966-7">(</span><span class="p" data-group-id="0385045966-8">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0385045966-8">]</span><span class="p" data-group-id="0385045966-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="1727359945-9">(</span><span class="p" data-group-id="1727359945-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1727359945-10">(</span><span class="p" data-group-id="1727359945-11">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1727359945-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1727359945-12">[</span><span class="p" data-group-id="1727359945-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1727359945-13">[</span><span class="p" data-group-id="1727359945-13">]</span><span class="p" data-group-id="1727359945-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="0385045966-9">(</span><span class="p" data-group-id="0385045966-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0385045966-10">(</span><span class="p" data-group-id="0385045966-11">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="0385045966-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0385045966-12">[</span><span class="p" data-group-id="0385045966-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0385045966-13">[</span><span class="p" data-group-id="0385045966-13">]</span><span class="p" data-group-id="0385045966-10">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="1727359945-14">(</span><span class="p" data-group-id="1727359945-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="1727359945-15">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="1727359945-15">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="0385045966-14">(</span><span class="p" data-group-id="0385045966-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="0385045966-15">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="0385045966-15">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="1727359945-16">(</span><span class="n">Ch</span><span class="p" data-group-id="1727359945-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="1727359945-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1727359945-18">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="1727359945-18">}</span><span class="p" data-group-id="1727359945-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="0385045966-16">(</span><span class="n">Ch</span><span class="p" data-group-id="0385045966-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="0385045966-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0385045966-18">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0385045966-18">}</span><span class="p" data-group-id="0385045966-17">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="1727359945-19">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="1727359945-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1727359945-20">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="1727359945-21">(</span><span class="p" data-group-id="1727359945-21">)</span><span class="p" data-group-id="1727359945-20">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="0385045966-19">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="0385045966-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0385045966-20">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="0385045966-21">(</span><span class="p" data-group-id="0385045966-21">)</span><span class="p" data-group-id="0385045966-20">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="1727359945-22">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="1727359945-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1727359945-23">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="1727359945-23">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="1727359945-24">(</span><span class="n">Chs</span><span class="p" data-group-id="1727359945-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1727359945-25">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="1727359945-25">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="0385045966-22">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0385045966-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0385045966-23">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="0385045966-23">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="0385045966-24">(</span><span class="n">Chs</span><span class="p" data-group-id="0385045966-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0385045966-25">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="0385045966-25">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="1727359945-26">(</span><span class="p" data-group-id="1727359945-27">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="1727359945-27">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="1727359945-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="1727359945-28">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="1727359945-28">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1727359945-29">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="1727359945-29">}</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><h2 id="starting-a-gen_server" class="section-heading">
│ │ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="0385045966-26">(</span><span class="p" data-group-id="0385045966-27">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0385045966-27">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0385045966-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="0385045966-28">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0385045966-28">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0385045966-29">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="0385045966-29">}</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><h2 id="starting-a-gen_server" class="section-heading">
│ │ │ │    <a href="#starting-a-gen_server" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting a Gen_Server</span>
│ │ │ │  </h2>
│ │ │ │  <p>In the example in the previous section, <code class="inline">gen_server</code> is started by calling
│ │ │ │ -<code class="inline">ch3:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="9040872482-1">(</span><span class="p" data-group-id="9040872482-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9040872482-2">(</span><span class="p" data-group-id="9040872482-3">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="9040872482-3">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9040872482-4">[</span><span class="p" data-group-id="9040872482-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9040872482-5">[</span><span class="p" data-group-id="9040872482-5">]</span><span class="p" data-group-id="9040872482-2">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9040872482-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="9040872482-6">}</span></code></pre><p><code class="inline">start_link/0</code> calls function <a href="../../../lib/stdlib/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a>.  This function
│ │ │ │ +<code class="inline">ch3:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="3138399345-1">(</span><span class="p" data-group-id="3138399345-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3138399345-2">(</span><span class="p" data-group-id="3138399345-3">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3138399345-3">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3138399345-4">[</span><span class="p" data-group-id="3138399345-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3138399345-5">[</span><span class="p" data-group-id="3138399345-5">]</span><span class="p" data-group-id="3138399345-2">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3138399345-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="3138399345-6">}</span></code></pre><p><code class="inline">start_link/0</code> calls function <a href="../../../lib/stdlib/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a>.  This function
│ │ │ │  spawns and links to a new process, a <code class="inline">gen_server</code>.</p><ul><li><p>The first argument, <code class="inline">{local, ch3}</code>, specifies the name.
│ │ │ │  The gen_server is then locally registered as <code class="inline">ch3</code>.</p><p>If the name is omitted, the <code class="inline">gen_server</code> is not registered. Instead its pid
│ │ │ │  must be used. The name can also be given as <code class="inline">{global, Name}</code>, in which case
│ │ │ │  the <code class="inline">gen_server</code> is registered using <a href="../../../lib/kernel/doc/html/global.html#register_name/2"><code class="inline">global:register_name/2</code></a>.</p></li><li><p>The second argument, <code class="inline">ch3</code>, is the name of the callback module, which is
│ │ │ │  the module where the callback functions are located.</p><p>The interface functions (<code class="inline">start_link/0</code>, <code class="inline">alloc/0</code>, and <code class="inline">free/1</code>) are located
│ │ │ │  in the same module as the callback functions (<code class="inline">init/1</code>, <code class="inline">handle_call/3</code>, and
│ │ │ │  <code class="inline">handle_cast/2</code>). It is usually good programming practice to have the code
│ │ │ │  corresponding to one process contained in a single module.</p></li><li><p>The third argument, <code class="inline">[]</code>, is a term that is passed as is to the callback
│ │ │ │  function <code class="inline">init</code>. Here, <code class="inline">init</code> does not need any indata and ignores the
│ │ │ │  argument.</p></li><li><p>The fourth argument, <code class="inline">[]</code>, is a list of options. See <a href="../../../lib/stdlib/doc/html/gen_server.html"><code class="inline">gen_server</code></a>
│ │ │ │  for the available options.</p></li></ul><p>If name registration succeeds, the new <code class="inline">gen_server</code> process calls the callback
│ │ │ │  function <code class="inline">ch3:init([])</code>. <code class="inline">init</code> is expected to return <code class="inline">{ok, State}</code>, where
│ │ │ │  <code class="inline">State</code> is the internal state of the <code class="inline">gen_server</code>. In this case, the state is
│ │ │ │ -the available channels.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="8078702495-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="8078702495-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8078702495-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="8078702495-3">(</span><span class="p" data-group-id="8078702495-3">)</span><span class="p" data-group-id="8078702495-2">}</span><span class="p">.</span></code></pre><p><a href="../../../lib/stdlib/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a> is synchronous. It does not return until the
│ │ │ │ +the available channels.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="7544503605-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="7544503605-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7544503605-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="7544503605-3">(</span><span class="p" data-group-id="7544503605-3">)</span><span class="p" data-group-id="7544503605-2">}</span><span class="p">.</span></code></pre><p><a href="../../../lib/stdlib/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a> is synchronous. It does not return until the
│ │ │ │  <code class="inline">gen_server</code> has been initialized and is ready to receive requests.</p><p><a href="../../../lib/stdlib/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a> must be used if the <code class="inline">gen_server</code> is part of
│ │ │ │  a supervision tree, meaning that it was started by a supervisor. There
│ │ │ │  is another function, <a href="../../../lib/stdlib/doc/html/gen_server.html#start/4"><code class="inline">gen_server:start/4</code></a>, to start a standalone
│ │ │ │  <code class="inline">gen_server</code> that is not part of a supervision tree.</p><h2 id="synchronous-requests-call" class="section-heading">
│ │ │ │    <a href="#synchronous-requests-call" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │ @@ -126,32 +126,32 @@
│ │ │ │  </h2>
│ │ │ │  <p>The synchronous request <code class="inline">alloc()</code> is implemented using <a href="../../../lib/stdlib/doc/html/gen_server.html#call/2"><code class="inline">gen_server:call/2</code></a>:</p><pre><code class="text">alloc() -&gt;
│ │ │ │      gen_server:call(ch3, alloc).</code></pre><p><code class="inline">ch3</code> is the name of the <code class="inline">gen_server</code> and must agree with the name
│ │ │ │  used to start it. <code class="inline">alloc</code> is the actual request.</p><p>The request is made into a message and sent to the <code class="inline">gen_server</code>.
│ │ │ │  When the request is received, the <code class="inline">gen_server</code> calls
│ │ │ │  <code class="inline">handle_call(Request, From, State)</code>, which is expected to return
│ │ │ │  a tuple <code class="inline">{reply,Reply,State1}</code>. <code class="inline">Reply</code> is the reply that is to be sent back
│ │ │ │ -to the client, and <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="1657254790-1">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="1657254790-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1657254790-2">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="1657254790-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="1657254790-3">(</span><span class="n">Chs</span><span class="p" data-group-id="1657254790-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1657254790-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="1657254790-4">}</span><span class="p">.</span></code></pre><p>In this case, the reply is the allocated channel <code class="inline">Ch</code> and the new state is the
│ │ │ │ +to the client, and <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="6424760957-1">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6424760957-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6424760957-2">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="6424760957-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="6424760957-3">(</span><span class="n">Chs</span><span class="p" data-group-id="6424760957-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6424760957-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="6424760957-4">}</span><span class="p">.</span></code></pre><p>In this case, the reply is the allocated channel <code class="inline">Ch</code> and the new state is the
│ │ │ │  set of remaining available channels <code class="inline">Chs2</code>.</p><p>Thus, the call <code class="inline">ch3:alloc()</code> returns the allocated channel <code class="inline">Ch</code> and the
│ │ │ │  <code class="inline">gen_server</code> then waits for new requests, now with an updated list of
│ │ │ │  available channels.</p><h2 id="asynchronous-requests-cast" class="section-heading">
│ │ │ │    <a href="#asynchronous-requests-cast" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Asynchronous Requests - Cast</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The asynchronous request <code class="inline">free(Ch)</code> is implemented using <a href="../../../lib/stdlib/doc/html/gen_server.html#cast/2"><code class="inline">gen_server:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">free</span><span class="p" data-group-id="8279242568-1">(</span><span class="n">Ch</span><span class="p" data-group-id="8279242568-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="8279242568-2">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8279242568-3">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8279242568-3">}</span><span class="p" data-group-id="8279242568-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch3</code> is the name of the <code class="inline">gen_server</code>. <code class="inline">{free, Ch}</code> is the actual request.</p><p>The request is made into a message and sent to the <code class="inline">gen_server</code>.
│ │ │ │ +<p>The asynchronous request <code class="inline">free(Ch)</code> is implemented using <a href="../../../lib/stdlib/doc/html/gen_server.html#cast/2"><code class="inline">gen_server:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">free</span><span class="p" data-group-id="3327224730-1">(</span><span class="n">Ch</span><span class="p" data-group-id="3327224730-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="3327224730-2">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3327224730-3">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3327224730-3">}</span><span class="p" data-group-id="3327224730-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch3</code> is the name of the <code class="inline">gen_server</code>. <code class="inline">{free, Ch}</code> is the actual request.</p><p>The request is made into a message and sent to the <code class="inline">gen_server</code>.
│ │ │ │  <code class="inline">cast</code>, and thus <code class="inline">free</code>, then returns <code class="inline">ok</code>.</p><p>When the request is received, the <code class="inline">gen_server</code> calls
│ │ │ │  <code class="inline">handle_cast(Request, State)</code>, which is expected to return a tuple
│ │ │ │ -<code class="inline">{noreply,State1}</code>. <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_cast</span><span class="p" data-group-id="4328132372-1">(</span><span class="p" data-group-id="4328132372-2">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4328132372-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4328132372-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="4328132372-3">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4328132372-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4328132372-4">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="4328132372-4">}</span><span class="p">.</span></code></pre><p>In this case, the new state is the updated list of available channels <code class="inline">Chs2</code>.
│ │ │ │ +<code class="inline">{noreply,State1}</code>. <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_cast</span><span class="p" data-group-id="5893133139-1">(</span><span class="p" data-group-id="5893133139-2">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="5893133139-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="5893133139-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="5893133139-3">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="5893133139-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5893133139-4">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="5893133139-4">}</span><span class="p">.</span></code></pre><p>In this case, the new state is the updated list of available channels <code class="inline">Chs2</code>.
│ │ │ │  The <code class="inline">gen_server</code> is now ready for new requests.</p><h2 id="stopping" class="section-heading">
│ │ │ │    <a href="#stopping" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Stopping</span>
│ │ │ │  </h2>
│ │ │ │  <h3 id="in-a-supervision-tree" class="section-heading">
│ │ │ │ @@ -162,65 +162,65 @@
│ │ │ │  </h3>
│ │ │ │  <p>If the <code class="inline">gen_server</code> is part of a supervision tree, no stop function is needed.
│ │ │ │  The <code class="inline">gen_server</code> is automatically terminated by its supervisor.  Exactly how
│ │ │ │  this is done is defined by a <a href="sup_princ.xhtml#shutdown">shutdown strategy</a>
│ │ │ │  set in the supervisor.</p><p>If it is necessary to clean up before termination, the shutdown strategy
│ │ │ │  must be a time-out value and the <code class="inline">gen_server</code> must be set to trap exit signals
│ │ │ │  in function <code class="inline">init</code>. When ordered to shutdown, the <code class="inline">gen_server</code> then calls
│ │ │ │ -the callback function <code class="inline">terminate(shutdown, State)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="6382408188-1">(</span><span class="n">Args</span><span class="p" data-group-id="6382408188-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +the callback function <code class="inline">terminate(shutdown, State)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="7372018516-1">(</span><span class="n">Args</span><span class="p" data-group-id="7372018516-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="6382408188-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6382408188-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="7372018516-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="7372018516-2">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6382408188-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6382408188-3">}</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7372018516-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7372018516-3">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="6382408188-4">(</span><span class="ss">shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6382408188-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="7372018516-4">(</span><span class="ss">shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7372018516-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Code for cleaning up here</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h3 id="standalone-gen_servers" class="section-heading">
│ │ │ │    <a href="#standalone-gen_servers" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Standalone Gen_Servers</span>
│ │ │ │  </h3>
│ │ │ │  <p>If the <code class="inline">gen_server</code> is not part of a supervision tree, a stop function
│ │ │ │  can be useful, for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">export</span><span class="p" data-group-id="3687929899-1">(</span><span class="p" data-group-id="3687929899-2">[</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3687929899-2">]</span><span class="p" data-group-id="3687929899-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">export</span><span class="p" data-group-id="1999312757-1">(</span><span class="p" data-group-id="1999312757-2">[</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1999312757-2">]</span><span class="p" data-group-id="1999312757-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="3687929899-3">(</span><span class="p" data-group-id="3687929899-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="3687929899-4">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p" data-group-id="3687929899-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="1999312757-3">(</span><span class="p" data-group-id="1999312757-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="1999312757-4">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p" data-group-id="1999312757-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="3687929899-5">(</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3687929899-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3687929899-6">{</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3687929899-6">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="3687929899-7">(</span><span class="p" data-group-id="3687929899-8">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3687929899-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3687929899-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="1999312757-5">(</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1999312757-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1999312757-6">{</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1999312757-6">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="1999312757-7">(</span><span class="p" data-group-id="1999312757-8">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="1999312757-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1999312757-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="3687929899-9">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3687929899-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="1999312757-9">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1999312757-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The callback function handling the <code class="inline">stop</code> request returns a tuple
│ │ │ │  <code class="inline">{stop,normal,State1}</code>, where <code class="inline">normal</code> specifies that it is
│ │ │ │  a normal termination and <code class="inline">State1</code> is a new value for the state
│ │ │ │  of the <code class="inline">gen_server</code>.  This causes the <code class="inline">gen_server</code> to call
│ │ │ │  <code class="inline">terminate(normal, State1)</code> and then it terminates gracefully.</p><h2 id="handling-other-messages" class="section-heading">
│ │ │ │    <a href="#handling-other-messages" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Handling Other Messages</span>
│ │ │ │  </h2>
│ │ │ │  <p>If the <code class="inline">gen_server</code> is to be able to receive other messages than requests,
│ │ │ │  the callback function <code class="inline">handle_info(Info, State)</code> must be implemented
│ │ │ │  to handle them.  Examples of other messages are exit messages,
│ │ │ │  if the <code class="inline">gen_server</code> is linked to other processes than the supervisor
│ │ │ │ -and it is trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="2017648679-1">(</span><span class="p" data-group-id="2017648679-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2017648679-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="2017648679-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +and it is trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="2941425725-1">(</span><span class="p" data-group-id="2941425725-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2941425725-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="2941425725-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Code to handle exits here.</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2017648679-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="2017648679-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="5125433381-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="5125433381-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2941425725-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="2941425725-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="0935712550-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="0935712550-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Code to convert state (and more) during code change.</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5125433381-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="5125433381-2">}</span><span class="p">.</span></code></pre>
│ │ │ │ +    </span><span class="p" data-group-id="0935712550-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="0935712550-2">}</span><span class="p">.</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/funs.xhtml
│ │ │ │ @@ -22,399 +22,399 @@
│ │ │ │      </h1>
│ │ │ │  <h2 id="map" class="section-heading">
│ │ │ │    <a href="#map" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">map</span>
│ │ │ │  </h2>
│ │ │ │ -<p>The following function, <code class="inline">double</code>, doubles every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="4065553039-1">(</span><span class="p" data-group-id="4065553039-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4065553039-2">]</span><span class="p" data-group-id="4065553039-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4065553039-3">[</span><span class="mi">2</span><span class="o">*</span><span class="n">H</span><span class="p">|</span><span class="nf">double</span><span class="p" data-group-id="4065553039-4">(</span><span class="n">T</span><span class="p" data-group-id="4065553039-4">)</span><span class="p" data-group-id="4065553039-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">double</span><span class="p" data-group-id="4065553039-5">(</span><span class="p" data-group-id="4065553039-6">[</span><span class="p" data-group-id="4065553039-6">]</span><span class="p" data-group-id="4065553039-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4065553039-7">[</span><span class="p" data-group-id="4065553039-7">]</span><span class="p">.</span></code></pre><p>Hence, the argument entered as input is doubled as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">double</span><span class="p" data-group-id="5624240947-1">(</span><span class="p" data-group-id="5624240947-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5624240947-2">]</span><span class="p" data-group-id="5624240947-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5624240947-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p" data-group-id="5624240947-3">]</span></code></pre><p>The following function, <code class="inline">add_one</code>, adds one to every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add_one</span><span class="p" data-group-id="7669501216-1">(</span><span class="p" data-group-id="7669501216-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7669501216-2">]</span><span class="p" data-group-id="7669501216-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7669501216-3">[</span><span class="n">H</span><span class="o">+</span><span class="mi">1</span><span class="p">|</span><span class="nf">add_one</span><span class="p" data-group-id="7669501216-4">(</span><span class="n">T</span><span class="p" data-group-id="7669501216-4">)</span><span class="p" data-group-id="7669501216-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">add_one</span><span class="p" data-group-id="7669501216-5">(</span><span class="p" data-group-id="7669501216-6">[</span><span class="p" data-group-id="7669501216-6">]</span><span class="p" data-group-id="7669501216-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7669501216-7">[</span><span class="p" data-group-id="7669501216-7">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> have a similar structure. This can be used
│ │ │ │ -by writing a function <code class="inline">map</code> that expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="7803858791-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7803858791-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7803858791-2">]</span><span class="p" data-group-id="7803858791-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7803858791-3">[</span><span class="n">F</span><span class="p" data-group-id="7803858791-4">(</span><span class="n">H</span><span class="p" data-group-id="7803858791-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="7803858791-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7803858791-5">)</span><span class="p" data-group-id="7803858791-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="7803858791-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7803858791-7">[</span><span class="p" data-group-id="7803858791-7">]</span><span class="p" data-group-id="7803858791-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7803858791-8">[</span><span class="p" data-group-id="7803858791-8">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> can now be expressed in terms of <code class="inline">map</code> as
│ │ │ │ -follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="7999955693-1">(</span><span class="n">L</span><span class="p" data-group-id="7999955693-1">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="7999955693-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7999955693-3">(</span><span class="n">X</span><span class="p" data-group-id="7999955693-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7999955693-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add_one</span><span class="p" data-group-id="7999955693-4">(</span><span class="n">L</span><span class="p" data-group-id="7999955693-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="7999955693-5">(</span><span class="nf">fun</span><span class="p" data-group-id="7999955693-6">(</span><span class="n">X</span><span class="p" data-group-id="7999955693-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7999955693-5">)</span><span class="p">.</span></code></pre><p><code class="inline">map(F, List)</code> is a function that takes a function <code class="inline">F</code> and a list <code class="inline">L</code> as
│ │ │ │ +<p>The following function, <code class="inline">double</code>, doubles every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="2296925115-1">(</span><span class="p" data-group-id="2296925115-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2296925115-2">]</span><span class="p" data-group-id="2296925115-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2296925115-3">[</span><span class="mi">2</span><span class="o">*</span><span class="n">H</span><span class="p">|</span><span class="nf">double</span><span class="p" data-group-id="2296925115-4">(</span><span class="n">T</span><span class="p" data-group-id="2296925115-4">)</span><span class="p" data-group-id="2296925115-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">double</span><span class="p" data-group-id="2296925115-5">(</span><span class="p" data-group-id="2296925115-6">[</span><span class="p" data-group-id="2296925115-6">]</span><span class="p" data-group-id="2296925115-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2296925115-7">[</span><span class="p" data-group-id="2296925115-7">]</span><span class="p">.</span></code></pre><p>Hence, the argument entered as input is doubled as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">double</span><span class="p" data-group-id="6023253052-1">(</span><span class="p" data-group-id="6023253052-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6023253052-2">]</span><span class="p" data-group-id="6023253052-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6023253052-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p" data-group-id="6023253052-3">]</span></code></pre><p>The following function, <code class="inline">add_one</code>, adds one to every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add_one</span><span class="p" data-group-id="1252674973-1">(</span><span class="p" data-group-id="1252674973-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1252674973-2">]</span><span class="p" data-group-id="1252674973-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1252674973-3">[</span><span class="n">H</span><span class="o">+</span><span class="mi">1</span><span class="p">|</span><span class="nf">add_one</span><span class="p" data-group-id="1252674973-4">(</span><span class="n">T</span><span class="p" data-group-id="1252674973-4">)</span><span class="p" data-group-id="1252674973-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">add_one</span><span class="p" data-group-id="1252674973-5">(</span><span class="p" data-group-id="1252674973-6">[</span><span class="p" data-group-id="1252674973-6">]</span><span class="p" data-group-id="1252674973-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1252674973-7">[</span><span class="p" data-group-id="1252674973-7">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> have a similar structure. This can be used
│ │ │ │ +by writing a function <code class="inline">map</code> that expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="5552151934-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5552151934-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5552151934-2">]</span><span class="p" data-group-id="5552151934-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5552151934-3">[</span><span class="n">F</span><span class="p" data-group-id="5552151934-4">(</span><span class="n">H</span><span class="p" data-group-id="5552151934-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="5552151934-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="5552151934-5">)</span><span class="p" data-group-id="5552151934-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="5552151934-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5552151934-7">[</span><span class="p" data-group-id="5552151934-7">]</span><span class="p" data-group-id="5552151934-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5552151934-8">[</span><span class="p" data-group-id="5552151934-8">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> can now be expressed in terms of <code class="inline">map</code> as
│ │ │ │ +follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="3039417158-1">(</span><span class="n">L</span><span class="p" data-group-id="3039417158-1">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="3039417158-2">(</span><span class="nf">fun</span><span class="p" data-group-id="3039417158-3">(</span><span class="n">X</span><span class="p" data-group-id="3039417158-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="3039417158-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add_one</span><span class="p" data-group-id="3039417158-4">(</span><span class="n">L</span><span class="p" data-group-id="3039417158-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="3039417158-5">(</span><span class="nf">fun</span><span class="p" data-group-id="3039417158-6">(</span><span class="n">X</span><span class="p" data-group-id="3039417158-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="3039417158-5">)</span><span class="p">.</span></code></pre><p><code class="inline">map(F, List)</code> is a function that takes a function <code class="inline">F</code> and a list <code class="inline">L</code> as
│ │ │ │  arguments and returns a new list, obtained by applying <code class="inline">F</code> to each of the
│ │ │ │  elements in <code class="inline">L</code>.</p><p>The process of abstracting out the common features of a number of different
│ │ │ │  programs is called <em>procedural abstraction</em>. Procedural abstraction can be used
│ │ │ │  to write several different functions that have a similar structure, but differ
│ │ │ │  in some minor detail. This is done as follows:</p><ol><li><em>Step 1.</em> Write one function that represents the common features of these
│ │ │ │  functions.</li><li><em>Step 2.</em> Parameterize the difference in terms of functions that are passed
│ │ │ │  as arguments to the common function.</li></ol><h2 id="foreach" class="section-heading">
│ │ │ │    <a href="#foreach" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">foreach</span>
│ │ │ │  </h2>
│ │ │ │  <p>This section illustrates procedural abstraction. Initially, the following two
│ │ │ │ -examples are written as conventional functions.</p><p>This function prints all elements of a list onto a stream:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="0508879192-1">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0508879192-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0508879192-2">]</span><span class="p" data-group-id="0508879192-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0508879192-3">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0508879192-4">[</span><span class="n">H</span><span class="p" data-group-id="0508879192-4">]</span><span class="p" data-group-id="0508879192-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">print_list</span><span class="p" data-group-id="0508879192-5">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="0508879192-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">print_list</span><span class="p" data-group-id="0508879192-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0508879192-7">[</span><span class="p" data-group-id="0508879192-7">]</span><span class="p" data-group-id="0508879192-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>This function broadcasts a message to a list of processes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">broadcast</span><span class="p" data-group-id="5239837668-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5239837668-2">[</span><span class="n">Pid</span><span class="p">|</span><span class="n">Pids</span><span class="p" data-group-id="5239837668-2">]</span><span class="p" data-group-id="5239837668-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +examples are written as conventional functions.</p><p>This function prints all elements of a list onto a stream:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="8001215182-1">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8001215182-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8001215182-2">]</span><span class="p" data-group-id="8001215182-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8001215182-3">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8001215182-4">[</span><span class="n">H</span><span class="p" data-group-id="8001215182-4">]</span><span class="p" data-group-id="8001215182-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">print_list</span><span class="p" data-group-id="8001215182-5">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="8001215182-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">print_list</span><span class="p" data-group-id="8001215182-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8001215182-7">[</span><span class="p" data-group-id="8001215182-7">]</span><span class="p" data-group-id="8001215182-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>This function broadcasts a message to a list of processes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">broadcast</span><span class="p" data-group-id="5022607990-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5022607990-2">[</span><span class="n">Pid</span><span class="p">|</span><span class="n">Pids</span><span class="p" data-group-id="5022607990-2">]</span><span class="p" data-group-id="5022607990-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Msg</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">broadcast</span><span class="p" data-group-id="5239837668-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">Pids</span><span class="p" data-group-id="5239837668-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">broadcast</span><span class="p" data-group-id="5239837668-4">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5239837668-5">[</span><span class="p" data-group-id="5239837668-5">]</span><span class="p" data-group-id="5239837668-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">broadcast</span><span class="p" data-group-id="5022607990-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">Pids</span><span class="p" data-group-id="5022607990-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">broadcast</span><span class="p" data-group-id="5022607990-4">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5022607990-5">[</span><span class="p" data-group-id="5022607990-5">]</span><span class="p" data-group-id="5022607990-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">true</span><span class="p">.</span></code></pre><p>These two functions have a similar structure. They both iterate over a list and
│ │ │ │  do something to each element in the list. The &quot;something&quot; is passed on as an
│ │ │ │ -extra argument to the function that does this.</p><p>The function <code class="inline">foreach</code> expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="3923730646-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3923730646-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3923730646-2">]</span><span class="p" data-group-id="3923730646-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">F</span><span class="p" data-group-id="3923730646-3">(</span><span class="n">H</span><span class="p" data-group-id="3923730646-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="3923730646-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="3923730646-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">foreach</span><span class="p" data-group-id="3923730646-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3923730646-6">[</span><span class="p" data-group-id="3923730646-6">]</span><span class="p" data-group-id="3923730646-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">print_list</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="6478531228-1">(</span><span class="nf">fun</span><span class="p" data-group-id="6478531228-2">(</span><span class="n">H</span><span class="p" data-group-id="6478531228-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6478531228-3">(</span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="6478531228-4">[</span><span class="n">H</span><span class="p" data-group-id="6478531228-4">]</span><span class="p" data-group-id="6478531228-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6478531228-1">)</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">broadcast</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="6637863089-1">(</span><span class="nf">fun</span><span class="p" data-group-id="6637863089-2">(</span><span class="n">Pid</span><span class="p" data-group-id="6637863089-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6637863089-1">)</span></code></pre><p><code class="inline">foreach</code> is evaluated for its side-effect and not its value. <code class="inline">foreach(Fun ,L)</code>
│ │ │ │ +extra argument to the function that does this.</p><p>The function <code class="inline">foreach</code> expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="1646846337-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1646846337-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1646846337-2">]</span><span class="p" data-group-id="1646846337-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">F</span><span class="p" data-group-id="1646846337-3">(</span><span class="n">H</span><span class="p" data-group-id="1646846337-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="1646846337-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="1646846337-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">foreach</span><span class="p" data-group-id="1646846337-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1646846337-6">[</span><span class="p" data-group-id="1646846337-6">]</span><span class="p" data-group-id="1646846337-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">print_list</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="2627938962-1">(</span><span class="nf">fun</span><span class="p" data-group-id="2627938962-2">(</span><span class="n">H</span><span class="p" data-group-id="2627938962-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2627938962-3">(</span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="2627938962-4">[</span><span class="n">H</span><span class="p" data-group-id="2627938962-4">]</span><span class="p" data-group-id="2627938962-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="2627938962-1">)</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">broadcast</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="0436998326-1">(</span><span class="nf">fun</span><span class="p" data-group-id="0436998326-2">(</span><span class="n">Pid</span><span class="p" data-group-id="0436998326-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="0436998326-1">)</span></code></pre><p><code class="inline">foreach</code> is evaluated for its side-effect and not its value. <code class="inline">foreach(Fun ,L)</code>
│ │ │ │  calls <code class="inline">Fun(X)</code> for each element <code class="inline">X</code> in <code class="inline">L</code> and the processing occurs in the
│ │ │ │  order that the elements were defined in <code class="inline">L</code>. <code class="inline">map</code> does not define the order in
│ │ │ │  which its elements are processed.</p><h2 id="syntax-of-funs" class="section-heading">
│ │ │ │    <a href="#syntax-of-funs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Syntax of Funs</span>
│ │ │ │  </h2>
│ │ │ │  <p>Funs are written with the following syntax (see
│ │ │ │ -<a href="../../../lib/../system/doc/html/expressions.xhtml#fun-expressions">Fun Expressions </a>for full description):</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2470976729-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">ArgN</span><span class="p" data-group-id="2470976729-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +<a href="../../../lib/../system/doc/html/expressions.xhtml#fun-expressions">Fun Expressions </a>for full description):</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="8283920981-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">ArgN</span><span class="p" data-group-id="8283920981-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │      </span><span class="k">end</span></code></pre><p>This creates an anonymous function of <code class="inline">N</code> arguments and binds it to the variable
│ │ │ │  <code class="inline">F</code>.</p><p>Another function, <code class="inline">FunctionName</code>, written in the same module, can be passed as
│ │ │ │  an argument, using the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">FunctionName</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>With this form of function reference, the function that is referred to does not
│ │ │ │  need to be exported from the module.</p><p>It is also possible to refer to a function defined in a different module, with
│ │ │ │ -the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Module</span><span class="p">:</span><span class="n">FunctionName</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>In this case, the function must be exported from the module in question.</p><p>The following program illustrates the different ways of creating funs:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8391542716-1">(</span><span class="ss">fun_test</span><span class="p" data-group-id="8391542716-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8391542716-2">(</span><span class="p" data-group-id="8391542716-3">[</span><span class="ss">t1</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">t2</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8391542716-3">]</span><span class="p" data-group-id="8391542716-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="8391542716-4">(</span><span class="ss">lists</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8391542716-5">[</span><span class="ss">map</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8391542716-5">]</span><span class="p" data-group-id="8391542716-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Module</span><span class="p">:</span><span class="n">FunctionName</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>In this case, the function must be exported from the module in question.</p><p>The following program illustrates the different ways of creating funs:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7923587707-1">(</span><span class="ss">fun_test</span><span class="p" data-group-id="7923587707-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7923587707-2">(</span><span class="p" data-group-id="7923587707-3">[</span><span class="ss">t1</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">t2</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7923587707-3">]</span><span class="p" data-group-id="7923587707-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="7923587707-4">(</span><span class="ss">lists</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7923587707-5">[</span><span class="ss">map</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7923587707-5">]</span><span class="p" data-group-id="7923587707-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">t1</span><span class="p" data-group-id="8391542716-6">(</span><span class="p" data-group-id="8391542716-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="8391542716-7">(</span><span class="nf">fun</span><span class="p" data-group-id="8391542716-8">(</span><span class="n">X</span><span class="p" data-group-id="8391542716-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8391542716-9">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8391542716-9">]</span><span class="p" data-group-id="8391542716-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">t1</span><span class="p" data-group-id="7923587707-6">(</span><span class="p" data-group-id="7923587707-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="7923587707-7">(</span><span class="nf">fun</span><span class="p" data-group-id="7923587707-8">(</span><span class="n">X</span><span class="p" data-group-id="7923587707-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7923587707-9">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7923587707-9">]</span><span class="p" data-group-id="7923587707-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">t2</span><span class="p" data-group-id="8391542716-10">(</span><span class="p" data-group-id="8391542716-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="8391542716-11">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8391542716-12">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8391542716-12">]</span><span class="p" data-group-id="8391542716-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">t2</span><span class="p" data-group-id="7923587707-10">(</span><span class="p" data-group-id="7923587707-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="7923587707-11">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7923587707-12">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7923587707-12">]</span><span class="p" data-group-id="7923587707-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">double</span><span class="p" data-group-id="8391542716-13">(</span><span class="n">X</span><span class="p" data-group-id="8391542716-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="p">.</span></code></pre><p>The fun <code class="inline">F</code> can be evaluated with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="p" data-group-id="5771959750-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Argn</span><span class="p" data-group-id="5771959750-1">)</span></code></pre><p>To check whether a term is a fun, use the test
│ │ │ │ -<a href="../../../lib/../erts/doc/html/erlang.html#is_function/1"><code class="inline">is_function/1</code></a> in a guard.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="9301959017-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="9301959017-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_function</span><span class="p" data-group-id="9301959017-2">(</span><span class="n">F</span><span class="p" data-group-id="9301959017-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="nf">apply</span><span class="p" data-group-id="9301959017-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="9301959017-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="9301959017-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9301959017-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="9301959017-5">(</span><span class="n">N</span><span class="p" data-group-id="9301959017-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">double</span><span class="p" data-group-id="7923587707-13">(</span><span class="n">X</span><span class="p" data-group-id="7923587707-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="p">.</span></code></pre><p>The fun <code class="inline">F</code> can be evaluated with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="p" data-group-id="1773477259-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Argn</span><span class="p" data-group-id="1773477259-1">)</span></code></pre><p>To check whether a term is a fun, use the test
│ │ │ │ +<a href="../../../lib/../erts/doc/html/erlang.html#is_function/1"><code class="inline">is_function/1</code></a> in a guard.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="1910617361-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="1910617361-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_function</span><span class="p" data-group-id="1910617361-2">(</span><span class="n">F</span><span class="p" data-group-id="1910617361-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="nf">apply</span><span class="p" data-group-id="1910617361-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="1910617361-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="1910617361-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="1910617361-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="1910617361-5">(</span><span class="n">N</span><span class="p" data-group-id="1910617361-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │     </span><span class="n">N</span><span class="p">.</span></code></pre><p>Funs are a distinct type. The BIFs <code class="inline">erlang:fun_info/1,2</code> can be used to retrieve
│ │ │ │  information about a fun, and the BIF <a href="../../../lib/../erts/doc/html/erlang.html#fun_to_list/1"><code class="inline">erlang:fun_to_list/1</code></a> returns a textual
│ │ │ │  representation of a fun. The <a href="../../../lib/../erts/doc/html/erlang.html#check_process_code/2"><code class="inline">check_process_code/2</code></a>
│ │ │ │  BIF returns <code class="inline">true</code> if the process contains funs that depend on the old version
│ │ │ │  of a module.</p><h2 id="variable-bindings-within-a-fun" class="section-heading">
│ │ │ │    <a href="#variable-bindings-within-a-fun" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Variable Bindings Within a Fun</span>
│ │ │ │  </h2>
│ │ │ │  <p>The scope rules for variables that occur in funs are as follows:</p><ul><li>All variables that occur in the head of a fun are assumed to be &quot;fresh&quot;
│ │ │ │  variables.</li><li>Variables that are defined before the fun, and that occur in function calls or
│ │ │ │ -guard tests within the fun, have the values they had outside the fun.</li><li>Variables cannot be exported from a fun.</li></ul><p>The following examples illustrate these rules:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="5321103187-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5321103187-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5321103187-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="5321103187-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="5321103187-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="5321103187-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="5321103187-4">(</span><span class="nf">fun</span><span class="p" data-group-id="5321103187-5">(</span><span class="n">X</span><span class="p" data-group-id="5321103187-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5321103187-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="5321103187-7">[</span><span class="n">X</span><span class="p" data-group-id="5321103187-7">]</span><span class="p" data-group-id="5321103187-6">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5321103187-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="5321103187-8">(</span><span class="n">Stream</span><span class="p" data-group-id="5321103187-8">)</span><span class="p">.</span></code></pre><p>Here, the variable <code class="inline">X</code>, defined in the head of the fun, is a new variable. The
│ │ │ │ +guard tests within the fun, have the values they had outside the fun.</li><li>Variables cannot be exported from a fun.</li></ul><p>The following examples illustrate these rules:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="0490316042-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="0490316042-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0490316042-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="0490316042-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="0490316042-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="0490316042-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="0490316042-4">(</span><span class="nf">fun</span><span class="p" data-group-id="0490316042-5">(</span><span class="n">X</span><span class="p" data-group-id="0490316042-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0490316042-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="0490316042-7">[</span><span class="n">X</span><span class="p" data-group-id="0490316042-7">]</span><span class="p" data-group-id="0490316042-6">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="0490316042-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="0490316042-8">(</span><span class="n">Stream</span><span class="p" data-group-id="0490316042-8">)</span><span class="p">.</span></code></pre><p>Here, the variable <code class="inline">X</code>, defined in the head of the fun, is a new variable. The
│ │ │ │  variable <code class="inline">Stream</code>, which is used within the fun, gets its value from the
│ │ │ │  <code class="inline">file:open</code> line.</p><p>As any variable that occurs in the head of a fun is considered a new variable,
│ │ │ │ -it is equally valid to write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="2689591292-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2689591292-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2689591292-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="2689591292-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="2689591292-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="2689591292-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="2689591292-4">(</span><span class="nf">fun</span><span class="p" data-group-id="2689591292-5">(</span><span class="n">File</span><span class="p" data-group-id="2689591292-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2689591292-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="2689591292-7">[</span><span class="n">File</span><span class="p" data-group-id="2689591292-7">]</span><span class="p" data-group-id="2689591292-6">)</span><span class="w">
│ │ │ │ -            </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2689591292-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="2689591292-8">(</span><span class="n">Stream</span><span class="p" data-group-id="2689591292-8">)</span><span class="p">.</span></code></pre><p>Here, <code class="inline">File</code> is used as the new variable instead of <code class="inline">X</code>. This is not so wise
│ │ │ │ +it is equally valid to write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="2778781247-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2778781247-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2778781247-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="2778781247-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="2778781247-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="2778781247-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="2778781247-4">(</span><span class="nf">fun</span><span class="p" data-group-id="2778781247-5">(</span><span class="n">File</span><span class="p" data-group-id="2778781247-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2778781247-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="2778781247-7">[</span><span class="n">File</span><span class="p" data-group-id="2778781247-7">]</span><span class="p" data-group-id="2778781247-6">)</span><span class="w">
│ │ │ │ +            </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2778781247-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="2778781247-8">(</span><span class="n">Stream</span><span class="p" data-group-id="2778781247-8">)</span><span class="p">.</span></code></pre><p>Here, <code class="inline">File</code> is used as the new variable instead of <code class="inline">X</code>. This is not so wise
│ │ │ │  because code in the fun body cannot refer to the variable <code class="inline">File</code>, which is
│ │ │ │  defined outside of the fun. Compiling this example gives the following
│ │ │ │  diagnostic:</p><pre><code class="text">./FileName.erl:Line: Warning: variable 'File'
│ │ │ │        shadowed in 'fun'</code></pre><p>This indicates that the variable <code class="inline">File</code>, which is defined inside the fun,
│ │ │ │  collides with the variable <code class="inline">File</code>, which is defined outside the fun.</p><p>The rules for importing variables into a fun has the consequence that certain
│ │ │ │  pattern matching operations must be moved into guard expressions and cannot be
│ │ │ │  written in the head of the fun. For example, you might write the following code
│ │ │ │  if you intend the first clause of <code class="inline">F</code> to be evaluated when the value of its
│ │ │ │ -argument is <code class="inline">Y</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="4613324499-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4613324499-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +argument is <code class="inline">Y</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="0488797432-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0488797432-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="nf">map</span><span class="p" data-group-id="4613324499-2">(</span><span class="nf">fun</span><span class="p" data-group-id="4613324499-3">(</span><span class="n">X</span><span class="p" data-group-id="4613324499-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">map</span><span class="p" data-group-id="0488797432-2">(</span><span class="nf">fun</span><span class="p" data-group-id="0488797432-3">(</span><span class="n">X</span><span class="p" data-group-id="0488797432-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │               </span><span class="p">;</span><span class="w">
│ │ │ │ -           </span><span class="p" data-group-id="4613324499-4">(</span><span class="p">_</span><span class="p" data-group-id="4613324499-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +           </span><span class="p" data-group-id="0488797432-4">(</span><span class="p">_</span><span class="p" data-group-id="0488797432-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │               </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4613324499-2">)</span><span class="w">
│ │ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>instead of writing the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="6189402872-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6189402872-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0488797432-2">)</span><span class="w">
│ │ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>instead of writing the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="0180508180-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0180508180-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="nf">map</span><span class="p" data-group-id="6189402872-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6189402872-3">(</span><span class="n">Y</span><span class="p" data-group-id="6189402872-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">map</span><span class="p" data-group-id="0180508180-2">(</span><span class="nf">fun</span><span class="p" data-group-id="0180508180-3">(</span><span class="n">Y</span><span class="p" data-group-id="0180508180-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │               </span><span class="p">;</span><span class="w">
│ │ │ │ -           </span><span class="p" data-group-id="6189402872-4">(</span><span class="p">_</span><span class="p" data-group-id="6189402872-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +           </span><span class="p" data-group-id="0180508180-4">(</span><span class="p">_</span><span class="p" data-group-id="0180508180-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │               </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6189402872-2">)</span><span class="w">
│ │ │ │ +        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0180508180-2">)</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="funs-and-module-lists" class="section-heading">
│ │ │ │    <a href="#funs-and-module-lists" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Funs and Module Lists</span>
│ │ │ │  </h2>
│ │ │ │  <p>The following examples show a dialogue with the Erlang shell. All the higher
│ │ │ │  order functions discussed are exported from the module <a href="../../../lib/stdlib/doc/html/lists.html"><code class="inline">lists</code></a>.</p><h3 id="map-1" class="section-heading">
│ │ │ │    <a href="#map-1" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">map</span>
│ │ │ │  </h3>
│ │ │ │ -<p><a href="../../../lib/stdlib/doc/html/lists.html#map/2"><code class="inline">lists:map/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="1683619553-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1683619553-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1683619553-2">]</span><span class="p" data-group-id="1683619553-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1683619553-3">[</span><span class="n">F</span><span class="p" data-group-id="1683619553-4">(</span><span class="n">H</span><span class="p" data-group-id="1683619553-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="1683619553-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="1683619553-5">)</span><span class="p" data-group-id="1683619553-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="1683619553-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1683619553-7">[</span><span class="p" data-group-id="1683619553-7">]</span><span class="p" data-group-id="1683619553-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1683619553-8">[</span><span class="p" data-group-id="1683619553-8">]</span><span class="p">.</span></code></pre><p>It returns the list obtained by applying the function to every argument in the
│ │ │ │ +<p><a href="../../../lib/stdlib/doc/html/lists.html#map/2"><code class="inline">lists:map/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="3053907370-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3053907370-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3053907370-2">]</span><span class="p" data-group-id="3053907370-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3053907370-3">[</span><span class="n">F</span><span class="p" data-group-id="3053907370-4">(</span><span class="n">H</span><span class="p" data-group-id="3053907370-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="3053907370-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="3053907370-5">)</span><span class="p" data-group-id="3053907370-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="3053907370-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3053907370-7">[</span><span class="p" data-group-id="3053907370-7">]</span><span class="p" data-group-id="3053907370-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3053907370-8">[</span><span class="p" data-group-id="3053907370-8">]</span><span class="p">.</span></code></pre><p>It returns the list obtained by applying the function to every argument in the
│ │ │ │  list.</p><p>When a new fun is defined in the shell, the value of the fun is printed as
│ │ │ │ -<code class="inline">Fun#&lt;erl_eval&gt;</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Double</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="8667761632-1">(</span><span class="n">X</span><span class="p" data-group-id="8667761632-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">Fun#&lt;erl_eval&gt;</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Double</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3167774880-1">(</span><span class="n">X</span><span class="p" data-group-id="3167774880-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="8667761632-2">(</span><span class="n">Double</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8667761632-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8667761632-3">]</span><span class="p" data-group-id="8667761632-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8667761632-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="8667761632-4">]</span></code></pre><h3 id="any" class="section-heading">
│ │ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="3167774880-2">(</span><span class="n">Double</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3167774880-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3167774880-3">]</span><span class="p" data-group-id="3167774880-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3167774880-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="3167774880-4">]</span></code></pre><h3 id="any" class="section-heading">
│ │ │ │    <a href="#any" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">any</span>
│ │ │ │  </h3>
│ │ │ │ -<p><a href="../../../lib/stdlib/doc/html/lists.html#any/2"><code class="inline">lists:any/2</code></a> takes a predicate <code class="inline">P</code> of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">any</span><span class="p" data-group-id="6187134093-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6187134093-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6187134093-2">]</span><span class="p" data-group-id="6187134093-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="6187134093-3">(</span><span class="n">H</span><span class="p" data-group-id="6187134093-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +<p><a href="../../../lib/stdlib/doc/html/lists.html#any/2"><code class="inline">lists:any/2</code></a> takes a predicate <code class="inline">P</code> of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">any</span><span class="p" data-group-id="2174042698-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2174042698-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2174042698-2">]</span><span class="p" data-group-id="2174042698-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="2174042698-3">(</span><span class="n">H</span><span class="p" data-group-id="2174042698-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">  </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">any</span><span class="p" data-group-id="6187134093-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="6187134093-4">)</span><span class="w">
│ │ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">any</span><span class="p" data-group-id="2174042698-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="2174042698-4">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">any</span><span class="p" data-group-id="6187134093-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6187134093-6">[</span><span class="p" data-group-id="6187134093-6">]</span><span class="p" data-group-id="6187134093-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">any</span><span class="p" data-group-id="2174042698-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2174042698-6">[</span><span class="p" data-group-id="2174042698-6">]</span><span class="p" data-group-id="2174042698-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">false</span><span class="p">.</span></code></pre><p>A predicate is a function that returns <code class="inline">true</code> or <code class="inline">false</code>. <code class="inline">any</code> is <code class="inline">true</code> if
│ │ │ │  there is a term <code class="inline">X</code> in the list such that <code class="inline">P(X)</code> is <code class="inline">true</code>.</p><p>A predicate <code class="inline">Big(X)</code> is defined, which is <code class="inline">true</code> if its argument is greater that
│ │ │ │ -10:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Big</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="7601040982-1">(</span><span class="n">X</span><span class="p" data-group-id="7601040982-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">10</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="p">;</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +10:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Big</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="6036058533-1">(</span><span class="n">X</span><span class="p" data-group-id="6036058533-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">10</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="p">;</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="7601040982-2">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7601040982-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7601040982-3">]</span><span class="p" data-group-id="7601040982-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="6036058533-2">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6036058533-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6036058533-3">]</span><span class="p" data-group-id="6036058533-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="7601040982-4">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7601040982-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7601040982-5">]</span><span class="p" data-group-id="7601040982-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="6036058533-4">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6036058533-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6036058533-5">]</span><span class="p" data-group-id="6036058533-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span></code></pre><h3 id="all" class="section-heading">
│ │ │ │    <a href="#all" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">all</span>
│ │ │ │  </h3>
│ │ │ │ -<p><a href="../../../lib/stdlib/doc/html/lists.html#all/2"><code class="inline">lists:all/2</code></a> has the same arguments as <code class="inline">any</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="2560858244-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2560858244-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2560858244-2">]</span><span class="p" data-group-id="2560858244-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="2560858244-3">(</span><span class="n">H</span><span class="p" data-group-id="2560858244-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">all</span><span class="p" data-group-id="2560858244-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="2560858244-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +<p><a href="../../../lib/stdlib/doc/html/lists.html#all/2"><code class="inline">lists:all/2</code></a> has the same arguments as <code class="inline">any</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="4218873034-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4218873034-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4218873034-2">]</span><span class="p" data-group-id="4218873034-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="4218873034-3">(</span><span class="n">H</span><span class="p" data-group-id="4218873034-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">all</span><span class="p" data-group-id="4218873034-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="4218873034-4">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="ss">false</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">all</span><span class="p" data-group-id="2560858244-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2560858244-6">[</span><span class="p" data-group-id="2560858244-6">]</span><span class="p" data-group-id="2560858244-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>It is <code class="inline">true</code> if the predicate applied to all elements in the list is <code class="inline">true</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="5994196304-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5994196304-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5994196304-2">]</span><span class="p" data-group-id="5994196304-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">all</span><span class="p" data-group-id="4218873034-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4218873034-6">[</span><span class="p" data-group-id="4218873034-6">]</span><span class="p" data-group-id="4218873034-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>It is <code class="inline">true</code> if the predicate applied to all elements in the list is <code class="inline">true</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="4501832688-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4501832688-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="4501832688-2">]</span><span class="p" data-group-id="4501832688-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="5994196304-3">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5994196304-4">[</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="5994196304-4">]</span><span class="p" data-group-id="5994196304-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="4501832688-3">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4501832688-4">[</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="4501832688-4">]</span><span class="p" data-group-id="4501832688-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span></code></pre><h3 id="foreach-1" class="section-heading">
│ │ │ │    <a href="#foreach-1" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">foreach</span>
│ │ │ │  </h3>
│ │ │ │ -<p><a href="../../../lib/stdlib/doc/html/lists.html#foreach/2"><code class="inline">lists:foreach/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="1738503317-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1738503317-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1738503317-2">]</span><span class="p" data-group-id="1738503317-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">F</span><span class="p" data-group-id="1738503317-3">(</span><span class="n">H</span><span class="p" data-group-id="1738503317-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="1738503317-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="1738503317-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">foreach</span><span class="p" data-group-id="1738503317-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1738503317-6">[</span><span class="p" data-group-id="1738503317-6">]</span><span class="p" data-group-id="1738503317-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +<p><a href="../../../lib/stdlib/doc/html/lists.html#foreach/2"><code class="inline">lists:foreach/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="4811177723-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4811177723-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4811177723-2">]</span><span class="p" data-group-id="4811177723-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">F</span><span class="p" data-group-id="4811177723-3">(</span><span class="n">H</span><span class="p" data-group-id="4811177723-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="4811177723-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="4811177723-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">foreach</span><span class="p" data-group-id="4811177723-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4811177723-6">[</span><span class="p" data-group-id="4811177723-6">]</span><span class="p" data-group-id="4811177723-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The function is applied to each argument in the list. <code class="inline">foreach</code> returns <code class="inline">ok</code>. It
│ │ │ │ -is only used for its side-effect:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="7987655312-1">(</span><span class="nf">fun</span><span class="p" data-group-id="7987655312-2">(</span><span class="n">X</span><span class="p" data-group-id="7987655312-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7987655312-3">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="7987655312-4">[</span><span class="n">X</span><span class="p" data-group-id="7987655312-4">]</span><span class="p" data-group-id="7987655312-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7987655312-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7987655312-5">]</span><span class="p" data-group-id="7987655312-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +is only used for its side-effect:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="3296375898-1">(</span><span class="nf">fun</span><span class="p" data-group-id="3296375898-2">(</span><span class="n">X</span><span class="p" data-group-id="3296375898-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3296375898-3">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="3296375898-4">[</span><span class="n">X</span><span class="p" data-group-id="3296375898-4">]</span><span class="p" data-group-id="3296375898-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3296375898-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3296375898-5">]</span><span class="p" data-group-id="3296375898-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">1</span><span class="w">
│ │ │ │  </span><span class="mi">2</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="w">
│ │ │ │  </span><span class="mi">4</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><h3 id="foldl" class="section-heading">
│ │ │ │    <a href="#foldl" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">foldl</span>
│ │ │ │  </h3>
│ │ │ │ -<p><a href="../../../lib/stdlib/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> takes a function of two arguments, an accumulator and a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foldl</span><span class="p" data-group-id="5063818037-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5063818037-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="5063818037-2">]</span><span class="p" data-group-id="5063818037-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">foldl</span><span class="p" data-group-id="5063818037-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="5063818037-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="5063818037-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="5063818037-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">foldl</span><span class="p" data-group-id="5063818037-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5063818037-6">[</span><span class="p" data-group-id="5063818037-6">]</span><span class="p" data-group-id="5063818037-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Accu</span><span class="p">.</span></code></pre><p>The function is called with two arguments. The first argument is the successive
│ │ │ │ +<p><a href="../../../lib/stdlib/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> takes a function of two arguments, an accumulator and a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foldl</span><span class="p" data-group-id="9757145173-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9757145173-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="9757145173-2">]</span><span class="p" data-group-id="9757145173-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">foldl</span><span class="p" data-group-id="9757145173-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="9757145173-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="9757145173-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9757145173-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">foldl</span><span class="p" data-group-id="9757145173-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9757145173-6">[</span><span class="p" data-group-id="9757145173-6">]</span><span class="p" data-group-id="9757145173-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Accu</span><span class="p">.</span></code></pre><p>The function is called with two arguments. The first argument is the successive
│ │ │ │  elements in the list. The second argument is the accumulator. The function must
│ │ │ │  return a new accumulator, which is used the next time the function is called.</p><p>If you have a list of lists <code class="inline">L = [&quot;I&quot;,&quot;like&quot;,&quot;Erlang&quot;]</code>, then you can sum the
│ │ │ │ -lengths of all the strings in <code class="inline">L</code> as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9263879029-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="9263879029-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9263879029-2">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="9263879029-2">]</span><span class="gp unselectable">
│ │ │ │ -10&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="9263879029-3">(</span><span class="nf">fun</span><span class="p" data-group-id="9263879029-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="9263879029-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="9263879029-5">(</span><span class="n">X</span><span class="p" data-group-id="9263879029-5">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="9263879029-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="mi">11</span></code></pre><p><a href="../../../lib/stdlib/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> works like a <code class="inline">while</code> loop in an imperative language:</p><pre><code class="makeup erlang" translate="no"><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="p" data-group-id="5380875922-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="5380875922-1">]</span><span class="p">,</span><span class="w">
│ │ │ │ +lengths of all the strings in <code class="inline">L</code> as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1258500078-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="1258500078-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1258500078-2">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="1258500078-2">]</span><span class="gp unselectable">
│ │ │ │ +10&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="1258500078-3">(</span><span class="nf">fun</span><span class="p" data-group-id="1258500078-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="1258500078-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="1258500078-5">(</span><span class="n">X</span><span class="p" data-group-id="1258500078-5">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="1258500078-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="mi">11</span></code></pre><p><a href="../../../lib/stdlib/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> works like a <code class="inline">while</code> loop in an imperative language:</p><pre><code class="makeup erlang" translate="no"><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="p" data-group-id="9983450747-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="9983450747-1">]</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="n">Sum</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="nf">while</span><span class="p" data-group-id="5380875922-2">(</span><span class="w"> </span><span class="n">L</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5380875922-3">[</span><span class="p" data-group-id="5380875922-3">]</span><span class="p" data-group-id="5380875922-2">)</span><span class="p" data-group-id="5380875922-4">{</span><span class="w">
│ │ │ │ -    </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="5380875922-5">(</span><span class="nf">head</span><span class="p" data-group-id="5380875922-6">(</span><span class="n">L</span><span class="p" data-group-id="5380875922-6">)</span><span class="p" data-group-id="5380875922-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tail</span><span class="p" data-group-id="5380875922-7">(</span><span class="n">L</span><span class="p" data-group-id="5380875922-7">)</span><span class="w">
│ │ │ │ +</span><span class="nf">while</span><span class="p" data-group-id="9983450747-2">(</span><span class="w"> </span><span class="n">L</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9983450747-3">[</span><span class="p" data-group-id="9983450747-3">]</span><span class="p" data-group-id="9983450747-2">)</span><span class="p" data-group-id="9983450747-4">{</span><span class="w">
│ │ │ │ +    </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="9983450747-5">(</span><span class="nf">head</span><span class="p" data-group-id="9983450747-6">(</span><span class="n">L</span><span class="p" data-group-id="9983450747-6">)</span><span class="p" data-group-id="9983450747-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tail</span><span class="p" data-group-id="9983450747-7">(</span><span class="n">L</span><span class="p" data-group-id="9983450747-7">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><h3 id="mapfoldl" class="section-heading">
│ │ │ │    <a href="#mapfoldl" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">mapfoldl</span>
│ │ │ │  </h3>
│ │ │ │ -<p><a href="../../../lib/stdlib/doc/html/lists.html#mapfoldl/3"><code class="inline">lists:mapfoldl/3</code></a> simultaneously maps and folds over a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">mapfoldl</span><span class="p" data-group-id="9201462238-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9201462238-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="9201462238-2">]</span><span class="p" data-group-id="9201462238-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9201462238-3">{</span><span class="n">R</span><span class="p">,</span><span class="n">Accu1</span><span class="p" data-group-id="9201462238-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="9201462238-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p" data-group-id="9201462238-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9201462238-5">{</span><span class="n">Rs</span><span class="p">,</span><span class="n">Accu2</span><span class="p" data-group-id="9201462238-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">mapfoldl</span><span class="p" data-group-id="9201462238-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu1</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9201462238-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9201462238-7">{</span><span class="p" data-group-id="9201462238-8">[</span><span class="n">R</span><span class="p">|</span><span class="n">Rs</span><span class="p" data-group-id="9201462238-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu2</span><span class="p" data-group-id="9201462238-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">mapfoldl</span><span class="p" data-group-id="9201462238-9">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9201462238-10">[</span><span class="p" data-group-id="9201462238-10">]</span><span class="p" data-group-id="9201462238-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9201462238-11">{</span><span class="p" data-group-id="9201462238-12">[</span><span class="p" data-group-id="9201462238-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="9201462238-11">}</span><span class="p">.</span></code></pre><p>The following example shows how to change all letters in <code class="inline">L</code> to upper case and
│ │ │ │ -then count them.</p><p>First the change to upper case:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Upcase</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="5513160416-1">(</span><span class="n">X</span><span class="p" data-group-id="5513160416-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w">  </span><span class="n">X</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="sc">$a</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5513160416-2">(</span><span class="n">X</span><span class="p" data-group-id="5513160416-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w">
│ │ │ │ +<p><a href="../../../lib/stdlib/doc/html/lists.html#mapfoldl/3"><code class="inline">lists:mapfoldl/3</code></a> simultaneously maps and folds over a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">mapfoldl</span><span class="p" data-group-id="5191889135-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5191889135-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="5191889135-2">]</span><span class="p" data-group-id="5191889135-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5191889135-3">{</span><span class="n">R</span><span class="p">,</span><span class="n">Accu1</span><span class="p" data-group-id="5191889135-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="5191889135-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p" data-group-id="5191889135-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5191889135-5">{</span><span class="n">Rs</span><span class="p">,</span><span class="n">Accu2</span><span class="p" data-group-id="5191889135-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">mapfoldl</span><span class="p" data-group-id="5191889135-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu1</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="5191889135-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5191889135-7">{</span><span class="p" data-group-id="5191889135-8">[</span><span class="n">R</span><span class="p">|</span><span class="n">Rs</span><span class="p" data-group-id="5191889135-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu2</span><span class="p" data-group-id="5191889135-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">mapfoldl</span><span class="p" data-group-id="5191889135-9">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5191889135-10">[</span><span class="p" data-group-id="5191889135-10">]</span><span class="p" data-group-id="5191889135-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5191889135-11">{</span><span class="p" data-group-id="5191889135-12">[</span><span class="p" data-group-id="5191889135-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="5191889135-11">}</span><span class="p">.</span></code></pre><p>The following example shows how to change all letters in <code class="inline">L</code> to upper case and
│ │ │ │ +then count them.</p><p>First the change to upper case:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Upcase</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="5007576696-1">(</span><span class="n">X</span><span class="p" data-group-id="5007576696-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w">  </span><span class="n">X</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="sc">$a</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5007576696-2">(</span><span class="n">X</span><span class="p" data-group-id="5007576696-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │  &gt; </span><span class="n">Upcase_word</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ │ -</span><span class="nf">fun</span><span class="p" data-group-id="5513160416-3">(</span><span class="n">X</span><span class="p" data-group-id="5513160416-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="5513160416-4">(</span><span class="n">Upcase</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="5513160416-4">)</span><span class="w">
│ │ │ │ +</span><span class="nf">fun</span><span class="p" data-group-id="5007576696-3">(</span><span class="n">X</span><span class="p" data-group-id="5007576696-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="5007576696-4">(</span><span class="n">Upcase</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="5007576696-4">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">Upcase_word</span><span class="p" data-group-id="5513160416-5">(</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="5513160416-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="n">Upcase_word</span><span class="p" data-group-id="5007576696-5">(</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="5007576696-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;ERLANG&quot;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="5513160416-6">(</span><span class="n">Upcase_word</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5513160416-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5513160416-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="5513160416-7">]</span></code></pre><p>Now, the fold and the map can be done at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">mapfoldl</span><span class="p" data-group-id="8367352249-1">(</span><span class="nf">fun</span><span class="p" data-group-id="8367352249-2">(</span><span class="n">Word</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="8367352249-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8367352249-3">{</span><span class="n">Upcase_word</span><span class="p" data-group-id="8367352249-4">(</span><span class="n">Word</span><span class="p" data-group-id="8367352249-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="8367352249-5">(</span><span class="n">Word</span><span class="p" data-group-id="8367352249-5">)</span><span class="p" data-group-id="8367352249-3">}</span><span class="w">
│ │ │ │ -</span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8367352249-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8367352249-6">{</span><span class="p" data-group-id="8367352249-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="8367352249-7">]</span><span class="p">,</span><span class="mi">11</span><span class="p" data-group-id="8367352249-6">}</span></code></pre><h3 id="filter" class="section-heading">
│ │ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="5007576696-6">(</span><span class="n">Upcase_word</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5007576696-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5007576696-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="5007576696-7">]</span></code></pre><p>Now, the fold and the map can be done at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">mapfoldl</span><span class="p" data-group-id="5510392103-1">(</span><span class="nf">fun</span><span class="p" data-group-id="5510392103-2">(</span><span class="n">Word</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="5510392103-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5510392103-3">{</span><span class="n">Upcase_word</span><span class="p" data-group-id="5510392103-4">(</span><span class="n">Word</span><span class="p" data-group-id="5510392103-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="5510392103-5">(</span><span class="n">Word</span><span class="p" data-group-id="5510392103-5">)</span><span class="p" data-group-id="5510392103-3">}</span><span class="w">
│ │ │ │ +</span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5510392103-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5510392103-6">{</span><span class="p" data-group-id="5510392103-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="5510392103-7">]</span><span class="p">,</span><span class="mi">11</span><span class="p" data-group-id="5510392103-6">}</span></code></pre><h3 id="filter" class="section-heading">
│ │ │ │    <a href="#filter" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">filter</span>
│ │ │ │  </h3>
│ │ │ │  <p><a href="../../../lib/stdlib/doc/html/lists.html#filter/2"><code class="inline">lists:filter/2</code></a> takes a predicate of one argument and a list and returns all elements
│ │ │ │ -in the list that satisfy the predicate:</p><pre><code class="makeup erlang" translate="no"><span class="nf">filter</span><span class="p" data-group-id="7436420873-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7436420873-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7436420873-2">]</span><span class="p" data-group-id="7436420873-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="7436420873-3">(</span><span class="n">H</span><span class="p" data-group-id="7436420873-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7436420873-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">filter</span><span class="p" data-group-id="7436420873-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7436420873-5">)</span><span class="p" data-group-id="7436420873-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="7436420873-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7436420873-6">)</span><span class="w">
│ │ │ │ +in the list that satisfy the predicate:</p><pre><code class="makeup erlang" translate="no"><span class="nf">filter</span><span class="p" data-group-id="7655311699-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7655311699-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7655311699-2">]</span><span class="p" data-group-id="7655311699-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="7655311699-3">(</span><span class="n">H</span><span class="p" data-group-id="7655311699-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7655311699-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">filter</span><span class="p" data-group-id="7655311699-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7655311699-5">)</span><span class="p" data-group-id="7655311699-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="7655311699-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7655311699-6">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">filter</span><span class="p" data-group-id="7436420873-7">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7436420873-8">[</span><span class="p" data-group-id="7436420873-8">]</span><span class="p" data-group-id="7436420873-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7436420873-9">[</span><span class="p" data-group-id="7436420873-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="2901146742-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2901146742-2">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="2901146742-2">]</span><span class="p" data-group-id="2901146742-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2901146742-3">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="2901146742-3">]</span></code></pre><p>Combining maps and filters enables writing of very succinct code. For example,
│ │ │ │ +</span><span class="nf">filter</span><span class="p" data-group-id="7655311699-7">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7655311699-8">[</span><span class="p" data-group-id="7655311699-8">]</span><span class="p" data-group-id="7655311699-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7655311699-9">[</span><span class="p" data-group-id="7655311699-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="5071131963-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5071131963-2">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="5071131963-2">]</span><span class="p" data-group-id="5071131963-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5071131963-3">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="5071131963-3">]</span></code></pre><p>Combining maps and filters enables writing of very succinct code. For example,
│ │ │ │  to define a set difference function <code class="inline">diff(L1, L2)</code> to be the difference between
│ │ │ │ -the lists <code class="inline">L1</code> and <code class="inline">L2</code>, the code can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">diff</span><span class="p" data-group-id="1287862473-1">(</span><span class="n">L1</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="1287862473-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">filter</span><span class="p" data-group-id="1287862473-2">(</span><span class="nf">fun</span><span class="p" data-group-id="1287862473-3">(</span><span class="n">X</span><span class="p" data-group-id="1287862473-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ow">not</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="1287862473-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="1287862473-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="1287862473-2">)</span><span class="p">.</span></code></pre><p>This gives the list of all elements in L1 that are not contained in L2.</p><p>The AND intersection of the list <code class="inline">L1</code> and <code class="inline">L2</code> is also easily defined:</p><pre><code class="makeup erlang" translate="no"><span class="nf">intersection</span><span class="p" data-group-id="7886983301-1">(</span><span class="n">L1</span><span class="p">,</span><span class="n">L2</span><span class="p" data-group-id="7886983301-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="7886983301-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7886983301-3">(</span><span class="n">X</span><span class="p" data-group-id="7886983301-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="7886983301-4">(</span><span class="n">X</span><span class="p">,</span><span class="n">L1</span><span class="p" data-group-id="7886983301-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="7886983301-2">)</span><span class="p">.</span></code></pre><h3 id="takewhile" class="section-heading">
│ │ │ │ +the lists <code class="inline">L1</code> and <code class="inline">L2</code>, the code can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">diff</span><span class="p" data-group-id="4545720542-1">(</span><span class="n">L1</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="4545720542-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">filter</span><span class="p" data-group-id="4545720542-2">(</span><span class="nf">fun</span><span class="p" data-group-id="4545720542-3">(</span><span class="n">X</span><span class="p" data-group-id="4545720542-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ow">not</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="4545720542-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="4545720542-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="4545720542-2">)</span><span class="p">.</span></code></pre><p>This gives the list of all elements in L1 that are not contained in L2.</p><p>The AND intersection of the list <code class="inline">L1</code> and <code class="inline">L2</code> is also easily defined:</p><pre><code class="makeup erlang" translate="no"><span class="nf">intersection</span><span class="p" data-group-id="5020353823-1">(</span><span class="n">L1</span><span class="p">,</span><span class="n">L2</span><span class="p" data-group-id="5020353823-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="5020353823-2">(</span><span class="nf">fun</span><span class="p" data-group-id="5020353823-3">(</span><span class="n">X</span><span class="p" data-group-id="5020353823-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="5020353823-4">(</span><span class="n">X</span><span class="p">,</span><span class="n">L1</span><span class="p" data-group-id="5020353823-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="5020353823-2">)</span><span class="p">.</span></code></pre><h3 id="takewhile" class="section-heading">
│ │ │ │    <a href="#takewhile" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">takewhile</span>
│ │ │ │  </h3>
│ │ │ │  <p><a href="../../../lib/stdlib/doc/html/lists.html#takewhile/2"><code class="inline">lists:takewhile/2</code></a> takes elements <code class="inline">X</code> from a list <code class="inline">L</code> as long as the predicate
│ │ │ │ -<code class="inline">P(X)</code> is true:</p><pre><code class="makeup erlang" translate="no"><span class="nf">takewhile</span><span class="p" data-group-id="9151715581-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9151715581-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9151715581-2">]</span><span class="p" data-group-id="9151715581-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="9151715581-3">(</span><span class="n">H</span><span class="p" data-group-id="9151715581-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9151715581-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">takewhile</span><span class="p" data-group-id="9151715581-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9151715581-5">)</span><span class="p" data-group-id="9151715581-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9151715581-6">[</span><span class="p" data-group-id="9151715581-6">]</span><span class="w">
│ │ │ │ +<code class="inline">P(X)</code> is true:</p><pre><code class="makeup erlang" translate="no"><span class="nf">takewhile</span><span class="p" data-group-id="9291322418-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9291322418-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9291322418-2">]</span><span class="p" data-group-id="9291322418-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="9291322418-3">(</span><span class="n">H</span><span class="p" data-group-id="9291322418-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9291322418-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">takewhile</span><span class="p" data-group-id="9291322418-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9291322418-5">)</span><span class="p" data-group-id="9291322418-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9291322418-6">[</span><span class="p" data-group-id="9291322418-6">]</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">takewhile</span><span class="p" data-group-id="9151715581-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9151715581-8">[</span><span class="p" data-group-id="9151715581-8">]</span><span class="p" data-group-id="9151715581-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9151715581-9">[</span><span class="p" data-group-id="9151715581-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">takewhile</span><span class="p" data-group-id="7834357564-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7834357564-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7834357564-2">]</span><span class="p" data-group-id="7834357564-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7834357564-3">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="7834357564-3">]</span></code></pre><h3 id="dropwhile" class="section-heading">
│ │ │ │ +</span><span class="nf">takewhile</span><span class="p" data-group-id="9291322418-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9291322418-8">[</span><span class="p" data-group-id="9291322418-8">]</span><span class="p" data-group-id="9291322418-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9291322418-9">[</span><span class="p" data-group-id="9291322418-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">takewhile</span><span class="p" data-group-id="3602814982-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3602814982-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3602814982-2">]</span><span class="p" data-group-id="3602814982-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3602814982-3">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="3602814982-3">]</span></code></pre><h3 id="dropwhile" class="section-heading">
│ │ │ │    <a href="#dropwhile" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">dropwhile</span>
│ │ │ │  </h3>
│ │ │ │ -<p><a href="../../../lib/stdlib/doc/html/lists.html#dropwhile/2"><code class="inline">lists:dropwhile/2</code></a> is the complement of <code class="inline">takewhile</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">dropwhile</span><span class="p" data-group-id="7552519167-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7552519167-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7552519167-2">]</span><span class="p" data-group-id="7552519167-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="7552519167-3">(</span><span class="n">H</span><span class="p" data-group-id="7552519167-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">dropwhile</span><span class="p" data-group-id="7552519167-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7552519167-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7552519167-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7552519167-5">]</span><span class="w">
│ │ │ │ +<p><a href="../../../lib/stdlib/doc/html/lists.html#dropwhile/2"><code class="inline">lists:dropwhile/2</code></a> is the complement of <code class="inline">takewhile</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">dropwhile</span><span class="p" data-group-id="6942681992-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6942681992-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6942681992-2">]</span><span class="p" data-group-id="6942681992-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="6942681992-3">(</span><span class="n">H</span><span class="p" data-group-id="6942681992-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">dropwhile</span><span class="p" data-group-id="6942681992-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="6942681992-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6942681992-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6942681992-5">]</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">dropwhile</span><span class="p" data-group-id="7552519167-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7552519167-7">[</span><span class="p" data-group-id="7552519167-7">]</span><span class="p" data-group-id="7552519167-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7552519167-8">[</span><span class="p" data-group-id="7552519167-8">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">dropwhile</span><span class="p" data-group-id="7882861479-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7882861479-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7882861479-2">]</span><span class="p" data-group-id="7882861479-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7882861479-3">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7882861479-3">]</span></code></pre><h3 id="splitwith" class="section-heading">
│ │ │ │ +</span><span class="nf">dropwhile</span><span class="p" data-group-id="6942681992-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6942681992-7">[</span><span class="p" data-group-id="6942681992-7">]</span><span class="p" data-group-id="6942681992-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6942681992-8">[</span><span class="p" data-group-id="6942681992-8">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">dropwhile</span><span class="p" data-group-id="3370502503-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3370502503-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3370502503-2">]</span><span class="p" data-group-id="3370502503-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3370502503-3">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3370502503-3">]</span></code></pre><h3 id="splitwith" class="section-heading">
│ │ │ │    <a href="#splitwith" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">splitwith</span>
│ │ │ │  </h3>
│ │ │ │  <p><a href="../../../lib/stdlib/doc/html/lists.html#splitwith/2"><code class="inline">lists:splitwith/2</code></a> splits the list <code class="inline">L</code> into the two sublists <code class="inline">{L1, L2}</code>, where
│ │ │ │ -<code class="inline">L = takewhile(P, L)</code> and <code class="inline">L2 = dropwhile(P, L)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">splitwith</span><span class="p" data-group-id="7228469270-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7228469270-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">splitwith</span><span class="p" data-group-id="7228469270-2">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7228469270-3">[</span><span class="p" data-group-id="7228469270-3">]</span><span class="p" data-group-id="7228469270-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">L = takewhile(P, L)</code> and <code class="inline">L2 = dropwhile(P, L)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">splitwith</span><span class="p" data-group-id="8675896884-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8675896884-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">splitwith</span><span class="p" data-group-id="8675896884-2">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8675896884-3">[</span><span class="p" data-group-id="8675896884-3">]</span><span class="p" data-group-id="8675896884-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">splitwith</span><span class="p" data-group-id="7228469270-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7228469270-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7228469270-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7228469270-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="7228469270-6">(</span><span class="n">H</span><span class="p" data-group-id="7228469270-6">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">splitwith</span><span class="p" data-group-id="7228469270-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7228469270-8">[</span><span class="n">H</span><span class="p">|</span><span class="n">L</span><span class="p" data-group-id="7228469270-8">]</span><span class="p" data-group-id="7228469270-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7228469270-9">{</span><span class="nf">reverse</span><span class="p" data-group-id="7228469270-10">(</span><span class="n">L</span><span class="p" data-group-id="7228469270-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7228469270-11">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7228469270-11">]</span><span class="p" data-group-id="7228469270-9">}</span><span class="w">
│ │ │ │ +</span><span class="nf">splitwith</span><span class="p" data-group-id="8675896884-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8675896884-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8675896884-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8675896884-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="8675896884-6">(</span><span class="n">H</span><span class="p" data-group-id="8675896884-6">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">splitwith</span><span class="p" data-group-id="8675896884-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8675896884-8">[</span><span class="n">H</span><span class="p">|</span><span class="n">L</span><span class="p" data-group-id="8675896884-8">]</span><span class="p" data-group-id="8675896884-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8675896884-9">{</span><span class="nf">reverse</span><span class="p" data-group-id="8675896884-10">(</span><span class="n">L</span><span class="p" data-group-id="8675896884-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8675896884-11">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8675896884-11">]</span><span class="p" data-group-id="8675896884-9">}</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">splitwith</span><span class="p" data-group-id="7228469270-12">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7228469270-13">[</span><span class="p" data-group-id="7228469270-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7228469270-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7228469270-14">{</span><span class="nf">reverse</span><span class="p" data-group-id="7228469270-15">(</span><span class="n">L</span><span class="p" data-group-id="7228469270-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7228469270-16">[</span><span class="p" data-group-id="7228469270-16">]</span><span class="p" data-group-id="7228469270-14">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">splitwith</span><span class="p" data-group-id="7696326313-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7696326313-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7696326313-2">]</span><span class="p" data-group-id="7696326313-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7696326313-3">{</span><span class="p" data-group-id="7696326313-4">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="7696326313-4">]</span><span class="p">,</span><span class="p" data-group-id="7696326313-5">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7696326313-5">]</span><span class="p" data-group-id="7696326313-3">}</span></code></pre><h2 id="funs-returning-funs" class="section-heading">
│ │ │ │ +</span><span class="nf">splitwith</span><span class="p" data-group-id="8675896884-12">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8675896884-13">[</span><span class="p" data-group-id="8675896884-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8675896884-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8675896884-14">{</span><span class="nf">reverse</span><span class="p" data-group-id="8675896884-15">(</span><span class="n">L</span><span class="p" data-group-id="8675896884-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8675896884-16">[</span><span class="p" data-group-id="8675896884-16">]</span><span class="p" data-group-id="8675896884-14">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">splitwith</span><span class="p" data-group-id="7405893248-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7405893248-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7405893248-2">]</span><span class="p" data-group-id="7405893248-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7405893248-3">{</span><span class="p" data-group-id="7405893248-4">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="7405893248-4">]</span><span class="p">,</span><span class="p" data-group-id="7405893248-5">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7405893248-5">]</span><span class="p" data-group-id="7405893248-3">}</span></code></pre><h2 id="funs-returning-funs" class="section-heading">
│ │ │ │    <a href="#funs-returning-funs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Funs Returning Funs</span>
│ │ │ │  </h2>
│ │ │ │  <p>So far, only functions that take funs as arguments have been described. More
│ │ │ │  powerful functions, that themselves return funs, can also be written. The
│ │ │ │  following examples illustrate these type of functions.</p><h3 id="simple-higher-order-functions" class="section-heading">
│ │ │ │    <a href="#simple-higher-order-functions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Simple Higher Order Functions</span>
│ │ │ │  </h3>
│ │ │ │  <p><code class="inline">Adder(X)</code> is a function that given <code class="inline">X</code>, returns a new function <code class="inline">G</code> such that
│ │ │ │ -<code class="inline">G(K)</code> returns <code class="inline">K + X</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Adder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="8027914394-1">(</span><span class="n">X</span><span class="p" data-group-id="8027914394-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="8027914394-2">(</span><span class="n">Y</span><span class="p" data-group-id="8027914394-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">G(K)</code> returns <code class="inline">K + X</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Adder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1824853672-1">(</span><span class="n">X</span><span class="p" data-group-id="1824853672-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1824853672-2">(</span><span class="n">Y</span><span class="p" data-group-id="1824853672-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">Add6</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Adder</span><span class="p" data-group-id="8027914394-3">(</span><span class="mi">6</span><span class="p" data-group-id="8027914394-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="n">Add6</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Adder</span><span class="p" data-group-id="1824853672-3">(</span><span class="mi">6</span><span class="p" data-group-id="1824853672-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">Add6</span><span class="p" data-group-id="8027914394-4">(</span><span class="mi">10</span><span class="p" data-group-id="8027914394-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="n">Add6</span><span class="p" data-group-id="1824853672-4">(</span><span class="mi">10</span><span class="p" data-group-id="1824853672-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">16</span></code></pre><h3 id="infinite-lists" class="section-heading">
│ │ │ │    <a href="#infinite-lists" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Infinite Lists</span>
│ │ │ │  </h3>
│ │ │ │ -<p>The idea is to write something like:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7911664426-1">(</span><span class="ss">lazy</span><span class="p" data-group-id="7911664426-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7911664426-2">(</span><span class="p" data-group-id="7911664426-3">[</span><span class="ss">ints_from</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7911664426-3">]</span><span class="p" data-group-id="7911664426-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">ints_from</span><span class="p" data-group-id="7911664426-4">(</span><span class="n">N</span><span class="p" data-group-id="7911664426-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">fun</span><span class="p" data-group-id="7911664426-5">(</span><span class="p" data-group-id="7911664426-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="7911664426-6">[</span><span class="n">N</span><span class="p">|</span><span class="nf">ints_from</span><span class="p" data-group-id="7911664426-7">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="7911664426-7">)</span><span class="p" data-group-id="7911664426-6">]</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Then proceed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">XX</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lazy</span><span class="p">:</span><span class="nf">ints_from</span><span class="p" data-group-id="3442154057-1">(</span><span class="mi">1</span><span class="p" data-group-id="3442154057-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>The idea is to write something like:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7454497327-1">(</span><span class="ss">lazy</span><span class="p" data-group-id="7454497327-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7454497327-2">(</span><span class="p" data-group-id="7454497327-3">[</span><span class="ss">ints_from</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7454497327-3">]</span><span class="p" data-group-id="7454497327-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">ints_from</span><span class="p" data-group-id="7454497327-4">(</span><span class="n">N</span><span class="p" data-group-id="7454497327-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">fun</span><span class="p" data-group-id="7454497327-5">(</span><span class="p" data-group-id="7454497327-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="7454497327-6">[</span><span class="n">N</span><span class="p">|</span><span class="nf">ints_from</span><span class="p" data-group-id="7454497327-7">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="7454497327-7">)</span><span class="p" data-group-id="7454497327-6">]</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Then proceed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">XX</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lazy</span><span class="p">:</span><span class="nf">ints_from</span><span class="p" data-group-id="3097491013-1">(</span><span class="mi">1</span><span class="p" data-group-id="3097491013-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">XX</span><span class="p" data-group-id="3442154057-2">(</span><span class="p" data-group-id="3442154057-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3442154057-3">[</span><span class="mi">1</span><span class="p">|</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="p" data-group-id="3442154057-3">]</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nf">hd</span><span class="p" data-group-id="3442154057-4">(</span><span class="n">XX</span><span class="p" data-group-id="3442154057-5">(</span><span class="p" data-group-id="3442154057-5">)</span><span class="p" data-group-id="3442154057-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="n">XX</span><span class="p" data-group-id="3097491013-2">(</span><span class="p" data-group-id="3097491013-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3097491013-3">[</span><span class="mi">1</span><span class="p">|</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="p" data-group-id="3097491013-3">]</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nf">hd</span><span class="p" data-group-id="3097491013-4">(</span><span class="n">XX</span><span class="p" data-group-id="3097491013-5">(</span><span class="p" data-group-id="3097491013-5">)</span><span class="p" data-group-id="3097491013-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tl</span><span class="p" data-group-id="3442154057-6">(</span><span class="n">XX</span><span class="p" data-group-id="3442154057-7">(</span><span class="p" data-group-id="3442154057-7">)</span><span class="p" data-group-id="3442154057-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tl</span><span class="p" data-group-id="3097491013-6">(</span><span class="n">XX</span><span class="p" data-group-id="3097491013-7">(</span><span class="p" data-group-id="3097491013-7">)</span><span class="p" data-group-id="3097491013-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nf">hd</span><span class="p" data-group-id="3442154057-8">(</span><span class="n">Y</span><span class="p" data-group-id="3442154057-9">(</span><span class="p" data-group-id="3442154057-9">)</span><span class="p" data-group-id="3442154057-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="nf">hd</span><span class="p" data-group-id="3097491013-8">(</span><span class="n">Y</span><span class="p" data-group-id="3097491013-9">(</span><span class="p" data-group-id="3097491013-9">)</span><span class="p" data-group-id="3097491013-8">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">2</span></code></pre><p>And so on. This is an example of &quot;lazy embedding&quot;.</p><h3 id="parsing" class="section-heading">
│ │ │ │    <a href="#parsing" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Parsing</span>
│ │ │ │  </h3>
│ │ │ │ -<p>The following examples show parsers of the following type:</p><pre><code class="makeup erlang" translate="no"><span class="n">Parser</span><span class="p" data-group-id="3535708188-1">(</span><span class="n">Toks</span><span class="p" data-group-id="3535708188-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3535708188-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tree</span><span class="p">,</span><span class="w"> </span><span class="n">Toks1</span><span class="p" data-group-id="3535708188-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">fail</span></code></pre><p><code class="inline">Toks</code> is the list of tokens to be parsed. A successful parse returns
│ │ │ │ +<p>The following examples show parsers of the following type:</p><pre><code class="makeup erlang" translate="no"><span class="n">Parser</span><span class="p" data-group-id="0778728587-1">(</span><span class="n">Toks</span><span class="p" data-group-id="0778728587-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0778728587-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tree</span><span class="p">,</span><span class="w"> </span><span class="n">Toks1</span><span class="p" data-group-id="0778728587-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">fail</span></code></pre><p><code class="inline">Toks</code> is the list of tokens to be parsed. A successful parse returns
│ │ │ │  <code class="inline">{ok, Tree, Toks1}</code>.</p><ul><li><code class="inline">Tree</code> is a parse tree.</li><li><code class="inline">Toks1</code> is a tail of <code class="inline">Tree</code> that contains symbols encountered after the
│ │ │ │  structure that was correctly parsed.</li></ul><p>An unsuccessful parse returns <code class="inline">fail</code>.</p><p>The following example illustrates a simple, functional parser that parses the
│ │ │ │  grammar:</p><pre><code class="text">(a | b) &amp; (c | d)</code></pre><p>The following code defines a function <code class="inline">pconst(X)</code> in the module <code class="inline">funparse</code>,
│ │ │ │ -which returns a fun that parses a list of tokens:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pconst</span><span class="p" data-group-id="2206976594-1">(</span><span class="n">X</span><span class="p" data-group-id="2206976594-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2206976594-2">(</span><span class="n">T</span><span class="p" data-group-id="2206976594-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +which returns a fun that parses a list of tokens:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pconst</span><span class="p" data-group-id="4078976493-1">(</span><span class="n">X</span><span class="p" data-group-id="4078976493-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="4078976493-2">(</span><span class="n">T</span><span class="p" data-group-id="4078976493-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │         </span><span class="k">case</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -           </span><span class="p" data-group-id="2206976594-3">[</span><span class="n">X</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="2206976594-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2206976594-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2206976594-5">{</span><span class="ss">const</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2206976594-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2206976594-4">}</span><span class="p">;</span><span class="w">
│ │ │ │ +           </span><span class="p" data-group-id="4078976493-3">[</span><span class="n">X</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="4078976493-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4078976493-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4078976493-5">{</span><span class="ss">const</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4078976493-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="4078976493-4">}</span><span class="p">;</span><span class="w">
│ │ │ │             </span><span class="p">_</span><span class="w">      </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">fail</span><span class="w">
│ │ │ │         </span><span class="k">end</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>This function can be used as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">pconst</span><span class="p" data-group-id="7837554569-1">(</span><span class="ss">a</span><span class="p" data-group-id="7837554569-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>This function can be used as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">pconst</span><span class="p" data-group-id="3947403502-1">(</span><span class="ss">a</span><span class="p" data-group-id="3947403502-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">funparse</span><span class="p">.</span><span class="mf">0.22674075</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">P1</span><span class="p" data-group-id="7837554569-2">(</span><span class="p" data-group-id="7837554569-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7837554569-3">]</span><span class="p" data-group-id="7837554569-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7837554569-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="7837554569-5">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="7837554569-5">}</span><span class="p">,</span><span class="p" data-group-id="7837554569-6">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7837554569-6">]</span><span class="p" data-group-id="7837554569-4">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="n">P1</span><span class="p" data-group-id="7837554569-7">(</span><span class="p" data-group-id="7837554569-8">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="7837554569-8">]</span><span class="p" data-group-id="7837554569-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +&gt; </span><span class="n">P1</span><span class="p" data-group-id="3947403502-2">(</span><span class="p" data-group-id="3947403502-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3947403502-3">]</span><span class="p" data-group-id="3947403502-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3947403502-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3947403502-5">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3947403502-5">}</span><span class="p">,</span><span class="p" data-group-id="3947403502-6">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3947403502-6">]</span><span class="p" data-group-id="3947403502-4">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="n">P1</span><span class="p" data-group-id="3947403502-7">(</span><span class="p" data-group-id="3947403502-8">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="3947403502-8">]</span><span class="p" data-group-id="3947403502-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">fail</span></code></pre><p>Next, the two higher order functions <code class="inline">pand</code> and <code class="inline">por</code> are defined. They combine
│ │ │ │ -primitive parsers to produce more complex parsers.</p><p>First <code class="inline">pand</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pand</span><span class="p" data-group-id="7573325186-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="7573325186-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="7573325186-2">(</span><span class="n">T</span><span class="p" data-group-id="7573325186-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="7573325186-3">(</span><span class="n">T</span><span class="p" data-group-id="7573325186-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="7573325186-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="7573325186-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="7573325186-5">(</span><span class="n">T1</span><span class="p" data-group-id="7573325186-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -                    </span><span class="p" data-group-id="7573325186-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="7573325186-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                        </span><span class="p" data-group-id="7573325186-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7573325186-8">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p" data-group-id="7573325186-8">}</span><span class="p" data-group-id="7573325186-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +primitive parsers to produce more complex parsers.</p><p>First <code class="inline">pand</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pand</span><span class="p" data-group-id="1237065312-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="1237065312-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="1237065312-2">(</span><span class="n">T</span><span class="p" data-group-id="1237065312-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="1237065312-3">(</span><span class="n">T</span><span class="p" data-group-id="1237065312-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="1237065312-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="1237065312-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="1237065312-5">(</span><span class="n">T1</span><span class="p" data-group-id="1237065312-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +                    </span><span class="p" data-group-id="1237065312-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="1237065312-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                        </span><span class="p" data-group-id="1237065312-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1237065312-8">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p" data-group-id="1237065312-8">}</span><span class="p" data-group-id="1237065312-7">}</span><span class="p">;</span><span class="w">
│ │ │ │                      </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                          </span><span class="ss">fail</span><span class="w">
│ │ │ │                  </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="ss">fail</span><span class="w">
│ │ │ │          </span><span class="k">end</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Given a parser <code class="inline">P1</code> for grammar <code class="inline">G1</code>, and a parser <code class="inline">P2</code> for grammar <code class="inline">G2</code>,
│ │ │ │  <code class="inline">pand(P1, P2)</code> returns a parser for the grammar, which consists of sequences of
│ │ │ │  tokens that satisfy <code class="inline">G1</code>, followed by sequences of tokens that satisfy <code class="inline">G2</code>.</p><p><code class="inline">por(P1, P2)</code> returns a parser for the language described by the grammar <code class="inline">G1</code> or
│ │ │ │ -<code class="inline">G2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">por</span><span class="p" data-group-id="5598759570-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="5598759570-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="5598759570-2">(</span><span class="n">T</span><span class="p" data-group-id="5598759570-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="5598759570-3">(</span><span class="n">T</span><span class="p" data-group-id="5598759570-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="5598759570-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5598759570-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="p" data-group-id="5598759570-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5598759570-6">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="n">R</span><span class="p" data-group-id="5598759570-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5598759570-5">}</span><span class="p">;</span><span class="w">
│ │ │ │ +<code class="inline">G2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">por</span><span class="p" data-group-id="4122895751-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="4122895751-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="4122895751-2">(</span><span class="n">T</span><span class="p" data-group-id="4122895751-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="4122895751-3">(</span><span class="n">T</span><span class="p" data-group-id="4122895751-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="4122895751-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="4122895751-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                </span><span class="p" data-group-id="4122895751-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122895751-6">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="n">R</span><span class="p" data-group-id="4122895751-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="4122895751-5">}</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="5598759570-7">(</span><span class="n">T</span><span class="p" data-group-id="5598759570-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -                    </span><span class="p" data-group-id="5598759570-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5598759570-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                        </span><span class="p" data-group-id="5598759570-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5598759570-10">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="n">R1</span><span class="p" data-group-id="5598759570-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5598759570-9">}</span><span class="p">;</span><span class="w">
│ │ │ │ +                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="4122895751-7">(</span><span class="n">T</span><span class="p" data-group-id="4122895751-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +                    </span><span class="p" data-group-id="4122895751-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="4122895751-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                        </span><span class="p" data-group-id="4122895751-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122895751-10">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="n">R1</span><span class="p" data-group-id="4122895751-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="4122895751-9">}</span><span class="p">;</span><span class="w">
│ │ │ │                      </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                          </span><span class="ss">fail</span><span class="w">
│ │ │ │                  </span><span class="k">end</span><span class="w">
│ │ │ │          </span><span class="k">end</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The original problem was to parse the grammar <code class="inline">(a | b) &amp; (c | d)</code>. The following
│ │ │ │ -code addresses this problem:</p><pre><code class="makeup erlang" translate="no"><span class="nf">grammar</span><span class="p" data-group-id="3174893192-1">(</span><span class="p" data-group-id="3174893192-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">pand</span><span class="p" data-group-id="3174893192-2">(</span><span class="w">
│ │ │ │ -         </span><span class="nf">por</span><span class="p" data-group-id="3174893192-3">(</span><span class="nf">pconst</span><span class="p" data-group-id="3174893192-4">(</span><span class="ss">a</span><span class="p" data-group-id="3174893192-4">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="3174893192-5">(</span><span class="ss">b</span><span class="p" data-group-id="3174893192-5">)</span><span class="p" data-group-id="3174893192-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="nf">por</span><span class="p" data-group-id="3174893192-6">(</span><span class="nf">pconst</span><span class="p" data-group-id="3174893192-7">(</span><span class="ss">c</span><span class="p" data-group-id="3174893192-7">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="3174893192-8">(</span><span class="ss">d</span><span class="p" data-group-id="3174893192-8">)</span><span class="p" data-group-id="3174893192-6">)</span><span class="p" data-group-id="3174893192-2">)</span><span class="p">.</span></code></pre><p>The following code adds a parser interface to the grammar:</p><pre><code class="makeup erlang" translate="no"><span class="nf">parse</span><span class="p" data-group-id="3637800411-1">(</span><span class="n">List</span><span class="p" data-group-id="3637800411-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3637800411-2">(</span><span class="nf">grammar</span><span class="p" data-group-id="3637800411-3">(</span><span class="p" data-group-id="3637800411-3">)</span><span class="p" data-group-id="3637800411-2">)</span><span class="p" data-group-id="3637800411-4">(</span><span class="n">List</span><span class="p" data-group-id="3637800411-4">)</span><span class="p">.</span></code></pre><p>The parser can be tested as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="7497093683-1">(</span><span class="p" data-group-id="7497093683-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7497093683-2">]</span><span class="p" data-group-id="7497093683-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7497093683-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="7497093683-4">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="7497093683-5">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="7497093683-6">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="7497093683-6">}</span><span class="p" data-group-id="7497093683-5">}</span><span class="p">,</span><span class="p" data-group-id="7497093683-7">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="7497093683-8">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7497093683-8">}</span><span class="p" data-group-id="7497093683-7">}</span><span class="p" data-group-id="7497093683-4">}</span><span class="p" data-group-id="7497093683-3">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="7497093683-9">(</span><span class="p" data-group-id="7497093683-10">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="7497093683-10">]</span><span class="p" data-group-id="7497093683-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7497093683-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="7497093683-12">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="7497093683-13">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="7497093683-14">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="7497093683-14">}</span><span class="p" data-group-id="7497093683-13">}</span><span class="p">,</span><span class="p" data-group-id="7497093683-15">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="7497093683-16">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="7497093683-16">}</span><span class="p" data-group-id="7497093683-15">}</span><span class="p" data-group-id="7497093683-12">}</span><span class="p" data-group-id="7497093683-11">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="7497093683-17">(</span><span class="p" data-group-id="7497093683-18">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7497093683-18">]</span><span class="p" data-group-id="7497093683-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7497093683-19">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="7497093683-20">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="7497093683-21">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="7497093683-22">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7497093683-22">}</span><span class="p" data-group-id="7497093683-21">}</span><span class="p">,</span><span class="p" data-group-id="7497093683-23">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="7497093683-24">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7497093683-24">}</span><span class="p" data-group-id="7497093683-23">}</span><span class="p" data-group-id="7497093683-20">}</span><span class="p" data-group-id="7497093683-19">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="7497093683-25">(</span><span class="p" data-group-id="7497093683-26">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="7497093683-26">]</span><span class="p" data-group-id="7497093683-25">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7497093683-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="7497093683-28">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="7497093683-29">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="7497093683-30">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7497093683-30">}</span><span class="p" data-group-id="7497093683-29">}</span><span class="p">,</span><span class="p" data-group-id="7497093683-31">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="7497093683-32">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="7497093683-32">}</span><span class="p" data-group-id="7497093683-31">}</span><span class="p" data-group-id="7497093683-28">}</span><span class="p" data-group-id="7497093683-27">}</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="7497093683-33">(</span><span class="p" data-group-id="7497093683-34">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7497093683-34">]</span><span class="p" data-group-id="7497093683-33">)</span><span class="p">.</span><span class="w">
│ │ │ │ +code addresses this problem:</p><pre><code class="makeup erlang" translate="no"><span class="nf">grammar</span><span class="p" data-group-id="4462299238-1">(</span><span class="p" data-group-id="4462299238-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">pand</span><span class="p" data-group-id="4462299238-2">(</span><span class="w">
│ │ │ │ +         </span><span class="nf">por</span><span class="p" data-group-id="4462299238-3">(</span><span class="nf">pconst</span><span class="p" data-group-id="4462299238-4">(</span><span class="ss">a</span><span class="p" data-group-id="4462299238-4">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="4462299238-5">(</span><span class="ss">b</span><span class="p" data-group-id="4462299238-5">)</span><span class="p" data-group-id="4462299238-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="nf">por</span><span class="p" data-group-id="4462299238-6">(</span><span class="nf">pconst</span><span class="p" data-group-id="4462299238-7">(</span><span class="ss">c</span><span class="p" data-group-id="4462299238-7">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="4462299238-8">(</span><span class="ss">d</span><span class="p" data-group-id="4462299238-8">)</span><span class="p" data-group-id="4462299238-6">)</span><span class="p" data-group-id="4462299238-2">)</span><span class="p">.</span></code></pre><p>The following code adds a parser interface to the grammar:</p><pre><code class="makeup erlang" translate="no"><span class="nf">parse</span><span class="p" data-group-id="5016581738-1">(</span><span class="n">List</span><span class="p" data-group-id="5016581738-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5016581738-2">(</span><span class="nf">grammar</span><span class="p" data-group-id="5016581738-3">(</span><span class="p" data-group-id="5016581738-3">)</span><span class="p" data-group-id="5016581738-2">)</span><span class="p" data-group-id="5016581738-4">(</span><span class="n">List</span><span class="p" data-group-id="5016581738-4">)</span><span class="p">.</span></code></pre><p>The parser can be tested as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="6668631836-1">(</span><span class="p" data-group-id="6668631836-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6668631836-2">]</span><span class="p" data-group-id="6668631836-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6668631836-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="6668631836-4">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="6668631836-5">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="6668631836-6">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="6668631836-6">}</span><span class="p" data-group-id="6668631836-5">}</span><span class="p">,</span><span class="p" data-group-id="6668631836-7">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="6668631836-8">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6668631836-8">}</span><span class="p" data-group-id="6668631836-7">}</span><span class="p" data-group-id="6668631836-4">}</span><span class="p" data-group-id="6668631836-3">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="6668631836-9">(</span><span class="p" data-group-id="6668631836-10">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="6668631836-10">]</span><span class="p" data-group-id="6668631836-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6668631836-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="6668631836-12">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="6668631836-13">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="6668631836-14">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="6668631836-14">}</span><span class="p" data-group-id="6668631836-13">}</span><span class="p">,</span><span class="p" data-group-id="6668631836-15">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6668631836-16">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="6668631836-16">}</span><span class="p" data-group-id="6668631836-15">}</span><span class="p" data-group-id="6668631836-12">}</span><span class="p" data-group-id="6668631836-11">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="6668631836-17">(</span><span class="p" data-group-id="6668631836-18">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6668631836-18">]</span><span class="p" data-group-id="6668631836-17">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6668631836-19">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="6668631836-20">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="6668631836-21">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6668631836-22">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6668631836-22">}</span><span class="p" data-group-id="6668631836-21">}</span><span class="p">,</span><span class="p" data-group-id="6668631836-23">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="6668631836-24">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6668631836-24">}</span><span class="p" data-group-id="6668631836-23">}</span><span class="p" data-group-id="6668631836-20">}</span><span class="p" data-group-id="6668631836-19">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="6668631836-25">(</span><span class="p" data-group-id="6668631836-26">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="6668631836-26">]</span><span class="p" data-group-id="6668631836-25">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6668631836-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="6668631836-28">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="6668631836-29">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6668631836-30">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6668631836-30">}</span><span class="p" data-group-id="6668631836-29">}</span><span class="p">,</span><span class="p" data-group-id="6668631836-31">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6668631836-32">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="6668631836-32">}</span><span class="p" data-group-id="6668631836-31">}</span><span class="p" data-group-id="6668631836-28">}</span><span class="p" data-group-id="6668631836-27">}</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="6668631836-33">(</span><span class="p" data-group-id="6668631836-34">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6668631836-34">]</span><span class="p" data-group-id="6668631836-33">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">fail</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/expressions.xhtml
│ │ │ │ @@ -56,81 +56,81 @@
│ │ │ │  </span><span class="n">Phone_number</span><span class="w">
│ │ │ │  </span><span class="p">_</span><span class="w">
│ │ │ │  </span><span class="p">_</span><span class="n">Height</span><span class="w">
│ │ │ │  </span><span class="ss">name@node</span></code></pre><p>Variables are bound to values using <a href="patterns.xhtml">pattern matching</a>. Erlang uses
│ │ │ │  <em>single assignment</em>, that is, a variable can only be bound once.</p><p>The <em>anonymous variable</em> is denoted by underscore (_) and can be used when a
│ │ │ │  variable is required but its value can be ignored.</p><p><em>Example:</em></p><pre><code class="text">[H|_] = [1,2,3]</code></pre><p>Variables starting with underscore (<code class="inline">_</code>), for example, <code class="inline">_Height</code>, are normal
│ │ │ │  variables, not anonymous. However, they are ignored by the compiler in the sense
│ │ │ │ -that they do not generate warnings.</p><p><em>Example:</em></p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="6244260665-1">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6244260665-2">[</span><span class="p" data-group-id="6244260665-2">]</span><span class="p" data-group-id="6244260665-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6244260665-3">[</span><span class="p" data-group-id="6244260665-3">]</span><span class="p">.</span></code></pre><p>can be rewritten to be more readable:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="5708843772-1">(</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5708843772-2">[</span><span class="p" data-group-id="5708843772-2">]</span><span class="p" data-group-id="5708843772-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5708843772-3">[</span><span class="p" data-group-id="5708843772-3">]</span><span class="p">.</span></code></pre><p>This causes a warning for an unused variable, <code class="inline">Elem</code>. To avoid the warning,
│ │ │ │ -the code can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="6199338448-1">(</span><span class="p">_</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6199338448-2">[</span><span class="p" data-group-id="6199338448-2">]</span><span class="p" data-group-id="6199338448-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6199338448-3">[</span><span class="p" data-group-id="6199338448-3">]</span><span class="p">.</span></code></pre><p>Notice that since variables starting with an underscore are not anonymous, the
│ │ │ │ -following example matches:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5975262417-1">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5975262417-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5975262417-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5975262417-2">}</span></code></pre><p>But this example fails:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0948363876-1">{</span><span class="p">_</span><span class="n">N</span><span class="p">,</span><span class="p">_</span><span class="n">N</span><span class="p" data-group-id="0948363876-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0948363876-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0948363876-2">}</span></code></pre><p>The scope for a variable is its function clause. Variables bound in a branch of
│ │ │ │ +that they do not generate warnings.</p><p><em>Example:</em></p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="6150900520-1">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6150900520-2">[</span><span class="p" data-group-id="6150900520-2">]</span><span class="p" data-group-id="6150900520-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6150900520-3">[</span><span class="p" data-group-id="6150900520-3">]</span><span class="p">.</span></code></pre><p>can be rewritten to be more readable:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="9964584064-1">(</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9964584064-2">[</span><span class="p" data-group-id="9964584064-2">]</span><span class="p" data-group-id="9964584064-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9964584064-3">[</span><span class="p" data-group-id="9964584064-3">]</span><span class="p">.</span></code></pre><p>This causes a warning for an unused variable, <code class="inline">Elem</code>. To avoid the warning,
│ │ │ │ +the code can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="8261618540-1">(</span><span class="p">_</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8261618540-2">[</span><span class="p" data-group-id="8261618540-2">]</span><span class="p" data-group-id="8261618540-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8261618540-3">[</span><span class="p" data-group-id="8261618540-3">]</span><span class="p">.</span></code></pre><p>Notice that since variables starting with an underscore are not anonymous, the
│ │ │ │ +following example matches:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7828962930-1">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7828962930-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7828962930-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7828962930-2">}</span></code></pre><p>But this example fails:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1370143584-1">{</span><span class="p">_</span><span class="n">N</span><span class="p">,</span><span class="p">_</span><span class="n">N</span><span class="p" data-group-id="1370143584-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1370143584-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1370143584-2">}</span></code></pre><p>The scope for a variable is its function clause. Variables bound in a branch of
│ │ │ │  an <code class="inline">if</code>, <code class="inline">case</code>, or <code class="inline">receive</code> expression must be bound in all branches to have a
│ │ │ │  value outside the expression. Otherwise they are regarded as unsafe outside
│ │ │ │  the expression.</p><p>For the <code class="inline">try</code> expression variable scoping is limited so that variables bound in
│ │ │ │  the expression are always unsafe outside the expression.</p><h2 id="patterns" class="section-heading">
│ │ │ │    <a href="#patterns" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Patterns</span>
│ │ │ │  </h2>
│ │ │ │  <p>A pattern has the same structure as a term but can contain unbound variables.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">Name1</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2871936705-1">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2871936705-1">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2871936705-2">{</span><span class="ss">error</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="2871936705-2">}</span></code></pre><p>Patterns are allowed in clause heads, <a href="expressions.xhtml#case">case expressions</a>,
│ │ │ │ +</span><span class="p" data-group-id="7661716771-1">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7661716771-1">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7661716771-2">{</span><span class="ss">error</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="7661716771-2">}</span></code></pre><p>Patterns are allowed in clause heads, <a href="expressions.xhtml#case">case expressions</a>,
│ │ │ │  <a href="expressions.xhtml#receive">receive expressions</a>, and
│ │ │ │  <a href="expressions.xhtml#the-match-operator">match expressions</a>.</p><h3 id="the-compound-pattern-operator" class="section-heading">
│ │ │ │    <a href="#the-compound-pattern-operator" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">The Compound Pattern Operator</span>
│ │ │ │  </h3>
│ │ │ │  <p>If <code class="inline">Pattern1</code> and <code class="inline">Pattern2</code> are valid patterns, the following is also a valid
│ │ │ │  pattern:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Pattern2</span></code></pre><p>When matched against a term, both <code class="inline">Pattern1</code> and <code class="inline">Pattern2</code> are matched against
│ │ │ │ -the term. The idea behind this feature is to avoid reconstruction of terms.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="1827156298-1">(</span><span class="p" data-group-id="1827156298-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="1827156298-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="1827156298-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Signal</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1827156298-3">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="1827156298-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +the term. The idea behind this feature is to avoid reconstruction of terms.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="1011228854-1">(</span><span class="p" data-group-id="1011228854-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="1011228854-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="1011228854-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Signal</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1011228854-3">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="1011228854-3">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="1827156298-4">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="1827156298-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ignore</span><span class="p">.</span></code></pre><p>can instead be written as</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="3560197525-1">(</span><span class="p" data-group-id="3560197525-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="3560197525-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="3560197525-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="1011228854-4">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="1011228854-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ignore</span><span class="p">.</span></code></pre><p>can instead be written as</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="8769810559-1">(</span><span class="p" data-group-id="8769810559-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8769810559-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="8769810559-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="3560197525-3">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="3560197525-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="8769810559-3">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="8769810559-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">ignore</span><span class="p">.</span></code></pre><p>The compound pattern operator does not imply that its operands are matched in
│ │ │ │  any particular order. That means that it is not legal to bind a variable in
│ │ │ │  <code class="inline">Pattern1</code> and use it in <code class="inline">Pattern2</code>, or vice versa.</p><h3 id="string-prefix-in-patterns" class="section-heading">
│ │ │ │    <a href="#string-prefix-in-patterns" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">String Prefix in Patterns</span>
│ │ │ │  </h3>
│ │ │ │ -<p>When matching strings, the following is a valid pattern:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="7721668824-1">(</span><span class="s">&quot;prefix&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="7721668824-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This is syntactic sugar for the equivalent, but harder to read:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="0904724402-1">(</span><span class="p" data-group-id="0904724402-2">[</span><span class="sc">$p</span><span class="p">,</span><span class="sc">$r</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$f</span><span class="p">,</span><span class="sc">$i</span><span class="p">,</span><span class="sc">$x</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="0904724402-2">]</span><span class="p" data-group-id="0904724402-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h3 id="expressions-in-patterns" class="section-heading">
│ │ │ │ +<p>When matching strings, the following is a valid pattern:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="3186407074-1">(</span><span class="s">&quot;prefix&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="3186407074-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This is syntactic sugar for the equivalent, but harder to read:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="2182284857-1">(</span><span class="p" data-group-id="2182284857-2">[</span><span class="sc">$p</span><span class="p">,</span><span class="sc">$r</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$f</span><span class="p">,</span><span class="sc">$i</span><span class="p">,</span><span class="sc">$x</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="2182284857-2">]</span><span class="p" data-group-id="2182284857-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h3 id="expressions-in-patterns" class="section-heading">
│ │ │ │    <a href="#expressions-in-patterns" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Expressions in Patterns</span>
│ │ │ │  </h3>
│ │ │ │  <p>An arithmetic expression can be used within a pattern if it meets both of the
│ │ │ │ -following two conditions:</p><ul><li>It uses only numeric or bitwise operators.</li><li>Its value can be evaluated to a constant when complied.</li></ul><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="p" data-group-id="1014799523-1">{</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="1014799523-1">}</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1014799523-2">{</span><span class="o">?</span><span class="n">THRESHOLD</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="1014799523-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="the-match-operator" class="section-heading">
│ │ │ │ +following two conditions:</p><ul><li>It uses only numeric or bitwise operators.</li><li>Its value can be evaluated to a constant when complied.</li></ul><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="p" data-group-id="5690648038-1">{</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="5690648038-1">}</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5690648038-2">{</span><span class="o">?</span><span class="n">THRESHOLD</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="5690648038-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="the-match-operator" class="section-heading">
│ │ │ │    <a href="#the-match-operator" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">The Match Operator</span>
│ │ │ │  </h2>
│ │ │ │  <p>The following matches <code class="inline">Pattern</code> against <code class="inline">Expr</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>If the matching succeeds, any unbound variable in the pattern becomes bound and
│ │ │ │  the value of <code class="inline">Expr</code> is returned.</p><p>If multiple match operators are applied in sequence, they will be evaluated from
│ │ │ │ -right to left.</p><p>If the matching fails, a <code class="inline">badmatch</code> run-time error occurs.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5322017694-1">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="5322017694-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5322017694-2">{</span><span class="ss">answer</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="5322017694-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5322017694-3">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5322017694-3">}</span><span class="gp unselectable">
│ │ │ │ +right to left.</p><p>If the matching fails, a <code class="inline">badmatch</code> run-time error occurs.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0062884534-1">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="0062884534-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0062884534-2">{</span><span class="ss">answer</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="0062884534-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0062884534-3">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0062884534-3">}</span><span class="gp unselectable">
│ │ │ │  2&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">answer</span><span class="gp unselectable">
│ │ │ │  3&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │ │  4&gt; </span><span class="n">T</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5322017694-4">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5322017694-4">}</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="p" data-group-id="5322017694-5">{</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="5322017694-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5322017694-6">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="5322017694-6">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0062884534-4">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0062884534-4">}</span><span class="gp unselectable">
│ │ │ │ +5&gt; </span><span class="p" data-group-id="0062884534-5">{</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="0062884534-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0062884534-6">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="0062884534-6">]</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no match of right-hand side value [1,2]</span></code></pre><p>Because multiple match operators are evaluated from right to left, it means
│ │ │ │  that:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Pattern2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">PatternN</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expression</span></code></pre><p>is equivalent to:</p><pre><code class="makeup erlang" translate="no"><span class="n">Temporary</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expression</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="n">PatternN</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Temporary</span><span class="p">,</span><span class="w">
│ │ │ │     </span><span class="p">.</span><span class="w">
│ │ │ │     </span><span class="p">.</span><span class="w">
│ │ │ │     </span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="n">Pattern2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Temporary</span><span class="p">,</span><span class="w">
│ │ │ │ @@ -144,30 +144,30 @@
│ │ │ │  can safely be skipped on a first reading.</p></section><p>The <code class="inline">=</code> character is used to denote two similar but distinct operators: the
│ │ │ │  match operator and the compound pattern operator. Which one is meant is
│ │ │ │  determined by context.</p><p>The <em>compound pattern operator</em> is used to construct a compound pattern from two
│ │ │ │  patterns. Compound patterns are accepted everywhere a pattern is accepted. A
│ │ │ │  compound pattern matches if all of its constituent patterns match. It is not
│ │ │ │  legal for a pattern that is part of a compound pattern to use variables (as keys
│ │ │ │  in map patterns or sizes in binary patterns) bound in other sub patterns of the
│ │ │ │ -same compound pattern.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">fun</span><span class="p" data-group-id="1067952592-1">(</span><span class="p" data-group-id="1067952592-2">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="1067952592-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1067952592-3">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="1067952592-3">}</span><span class="p" data-group-id="1067952592-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +same compound pattern.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">fun</span><span class="p" data-group-id="9372670731-1">(</span><span class="p" data-group-id="9372670731-2">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="9372670731-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9372670731-3">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="9372670731-3">}</span><span class="p" data-group-id="9372670731-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">* 1:7: variable &#39;Key&#39; is unbound</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1067952592-4">(</span><span class="p" data-group-id="1067952592-5">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="1067952592-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">E</span><span class="p" data-group-id="1067952592-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1067952592-6">{</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="1067952592-6">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="1067952592-7">(</span><span class="p" data-group-id="1067952592-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1067952592-8">}</span><span class="p" data-group-id="1067952592-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1067952592-9">{</span><span class="p" data-group-id="1067952592-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1067952592-10">}</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1067952592-9">}</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="n">G</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1067952592-11">(</span><span class="p" data-group-id="1067952592-12">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">B</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="1067952592-12">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1067952592-13">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="1067952592-13">&gt;&gt;</span><span class="p" data-group-id="1067952592-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1067952592-14">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="1067952592-14">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">G</span><span class="p" data-group-id="1067952592-15">(</span><span class="p" data-group-id="1067952592-16">&lt;&lt;</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p" data-group-id="1067952592-16">&gt;&gt;</span><span class="p" data-group-id="1067952592-15">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1067952592-17">{</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p">,</span><span class="mi">10795</span><span class="p" data-group-id="1067952592-17">}</span></code></pre><p>The <em>match operator</em> is allowed everywhere an expression is allowed. It is used
│ │ │ │ +2&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="9372670731-4">(</span><span class="p" data-group-id="9372670731-5">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="9372670731-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">E</span><span class="p" data-group-id="9372670731-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9372670731-6">{</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="9372670731-6">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="9372670731-7">(</span><span class="p" data-group-id="9372670731-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9372670731-8">}</span><span class="p" data-group-id="9372670731-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9372670731-9">{</span><span class="p" data-group-id="9372670731-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9372670731-10">}</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9372670731-9">}</span><span class="gp unselectable">
│ │ │ │ +3&gt; </span><span class="n">G</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="9372670731-11">(</span><span class="p" data-group-id="9372670731-12">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">B</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="9372670731-12">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9372670731-13">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9372670731-13">&gt;&gt;</span><span class="p" data-group-id="9372670731-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9372670731-14">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="9372670731-14">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">G</span><span class="p" data-group-id="9372670731-15">(</span><span class="p" data-group-id="9372670731-16">&lt;&lt;</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p" data-group-id="9372670731-16">&gt;&gt;</span><span class="p" data-group-id="9372670731-15">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9372670731-17">{</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p">,</span><span class="mi">10795</span><span class="p" data-group-id="9372670731-17">}</span></code></pre><p>The <em>match operator</em> is allowed everywhere an expression is allowed. It is used
│ │ │ │  to match the value of an expression to a pattern. If multiple match operators
│ │ │ │ -are applied in sequence, they will be evaluated from right to left.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6739023938-1">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="6739023938-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6739023938-2">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="6739023938-2">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nf">f</span><span class="p" data-group-id="6739023938-3">(</span><span class="n">Key</span><span class="p" data-group-id="6739023938-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6739023938-4">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="6739023938-4">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6739023938-5">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="6739023938-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ │ +are applied in sequence, they will be evaluated from right to left.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0683841574-1">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="0683841574-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0683841574-2">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="0683841574-2">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nf">f</span><span class="p" data-group-id="0683841574-3">(</span><span class="n">Key</span><span class="p" data-group-id="0683841574-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683841574-4">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="0683841574-4">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0683841574-5">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="0683841574-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">value</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nf">f</span><span class="p" data-group-id="6739023938-6">(</span><span class="n">Key</span><span class="p" data-group-id="6739023938-6">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6739023938-7">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="6739023938-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6739023938-8">(</span><span class="p" data-group-id="6739023938-9">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="6739023938-9">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p" data-group-id="6739023938-8">)</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nf">f</span><span class="p" data-group-id="0683841574-6">(</span><span class="n">Key</span><span class="p" data-group-id="0683841574-6">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683841574-7">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="0683841574-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0683841574-8">(</span><span class="p" data-group-id="0683841574-9">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="0683841574-9">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p" data-group-id="0683841574-8">)</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">value</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nf">f</span><span class="p" data-group-id="6739023938-10">(</span><span class="n">Key</span><span class="p" data-group-id="6739023938-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6739023938-11">(</span><span class="p" data-group-id="6739023938-12">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="6739023938-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6739023938-13">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="6739023938-13">}</span><span class="p" data-group-id="6739023938-11">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nf">f</span><span class="p" data-group-id="0683841574-10">(</span><span class="n">Key</span><span class="p" data-group-id="0683841574-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683841574-11">(</span><span class="p" data-group-id="0683841574-12">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="0683841574-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0683841574-13">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="0683841574-13">}</span><span class="p" data-group-id="0683841574-11">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">* 1:12: variable &#39;Key&#39; is unbound</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="p" data-group-id="6739023938-14">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">Y</span><span class="p" data-group-id="6739023938-14">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">begin</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6739023938-15">&lt;&lt;</span><span class="mi">42</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="6739023938-15">&gt;&gt;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="p" data-group-id="0683841574-14">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">Y</span><span class="p" data-group-id="0683841574-14">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">begin</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683841574-15">&lt;&lt;</span><span class="mi">42</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0683841574-15">&gt;&gt;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span></code></pre><p>The expression at prompt <code class="inline">2&gt;</code> first matches the value of variable <code class="inline">M</code> against
│ │ │ │  pattern <code class="inline">#{key := Key}</code>, binding variable <code class="inline">Key</code>. It then matches the value of
│ │ │ │  <code class="inline">M</code> against pattern <code class="inline">#{Key := Value}</code> using variable <code class="inline">Key</code> as the key, binding
│ │ │ │  variable <code class="inline">Value</code>.</p><p>The expression at prompt <code class="inline">3&gt;</code> matches expression <code class="inline">(#{key := Key} = M)</code> against
│ │ │ │  pattern <code class="inline">#{Key := Value}</code>. The expression inside the parentheses is evaluated
│ │ │ │  first. That is, <code class="inline">M</code> is matched against <code class="inline">#{key := Key}</code>, and then the value of
│ │ │ │  <code class="inline">M</code> is matched against pattern <code class="inline">#{Key := Value}</code>. That is the same evaluation
│ │ │ │ @@ -181,30 +181,30 @@
│ │ │ │  binding variable <code class="inline">Y</code> and creating a binary. The binary is then matched against
│ │ │ │  pattern <code class="inline">&lt;&lt;X:Y&gt;&gt;</code> using the value of <code class="inline">Y</code> as the size of the segment.</p><h2 id="function-calls" class="section-heading">
│ │ │ │    <a href="#function-calls" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Function Calls</span>
│ │ │ │  </h2>
│ │ │ │ -<pre><code class="makeup erlang" translate="no"><span class="n">ExprF</span><span class="p" data-group-id="8069991115-1">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="8069991115-1">)</span><span class="w">
│ │ │ │ -</span><span class="n">ExprM</span><span class="p">:</span><span class="n">ExprF</span><span class="p" data-group-id="8069991115-2">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="8069991115-2">)</span></code></pre><p>In the first form of function calls, <code class="inline">ExprM:ExprF(Expr1,...,ExprN)</code>, each of
│ │ │ │ +<pre><code class="makeup erlang" translate="no"><span class="n">ExprF</span><span class="p" data-group-id="9153709334-1">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="9153709334-1">)</span><span class="w">
│ │ │ │ +</span><span class="n">ExprM</span><span class="p">:</span><span class="n">ExprF</span><span class="p" data-group-id="9153709334-2">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="9153709334-2">)</span></code></pre><p>In the first form of function calls, <code class="inline">ExprM:ExprF(Expr1,...,ExprN)</code>, each of
│ │ │ │  <code class="inline">ExprM</code> and <code class="inline">ExprF</code> must be an atom or an expression that evaluates to an atom.
│ │ │ │  The function is said to be called by using the <em>fully qualified function name</em>.
│ │ │ │ -This is often referred to as a <em>remote</em> or <em>external function call</em>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="0356180657-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="0356180657-1">)</span></code></pre><p>In the second form of function calls, <code class="inline">ExprF(Expr1,...,ExprN)</code>, <code class="inline">ExprF</code> must be
│ │ │ │ +This is often referred to as a <em>remote</em> or <em>external function call</em>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="2683587687-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2683587687-1">)</span></code></pre><p>In the second form of function calls, <code class="inline">ExprF(Expr1,...,ExprN)</code>, <code class="inline">ExprF</code> must be
│ │ │ │  an atom or evaluate to a fun.</p><p>If <code class="inline">ExprF</code> is an atom, the function is said to be called by using the
│ │ │ │  <em>implicitly qualified function name</em>. If the function <code class="inline">ExprF</code> is locally
│ │ │ │  defined, it is called. Alternatively, if <code class="inline">ExprF</code> is explicitly imported from the
│ │ │ │  <code class="inline">M</code> module, <code class="inline">M:ExprF(Expr1,...,ExprN)</code> is called. If <code class="inline">ExprF</code> is neither declared
│ │ │ │  locally nor explicitly imported, <code class="inline">ExprF</code> must be the name of an automatically
│ │ │ │ -imported BIF.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="9395646298-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9395646298-1">)</span><span class="w">
│ │ │ │ -</span><span class="nf">spawn</span><span class="p" data-group-id="9395646298-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9395646298-3">[</span><span class="p" data-group-id="9395646298-3">]</span><span class="p" data-group-id="9395646298-2">)</span></code></pre><p><em>Examples</em> where <code class="inline">ExprF</code> is a fun:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="9341901052-1">(</span><span class="n">X</span><span class="p" data-group-id="9341901052-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Fun1</span><span class="p" data-group-id="9341901052-2">(</span><span class="mi">3</span><span class="p" data-group-id="9341901052-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +imported BIF.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="3202161224-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3202161224-1">)</span><span class="w">
│ │ │ │ +</span><span class="nf">spawn</span><span class="p" data-group-id="3202161224-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3202161224-3">[</span><span class="p" data-group-id="3202161224-3">]</span><span class="p" data-group-id="3202161224-2">)</span></code></pre><p><em>Examples</em> where <code class="inline">ExprF</code> is a fun:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="8087750670-1">(</span><span class="n">X</span><span class="p" data-group-id="8087750670-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Fun1</span><span class="p" data-group-id="8087750670-2">(</span><span class="mi">3</span><span class="p" data-group-id="8087750670-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="k">fun</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="ss">append</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9341901052-3">(</span><span class="p" data-group-id="9341901052-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9341901052-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9341901052-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="9341901052-5">]</span><span class="p" data-group-id="9341901052-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9341901052-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="9341901052-6">]</span><span class="w">
│ │ │ │ +2&gt; </span><span class="k">fun</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="ss">append</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8087750670-3">(</span><span class="p" data-group-id="8087750670-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8087750670-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8087750670-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="8087750670-5">]</span><span class="p" data-group-id="8087750670-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8087750670-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="8087750670-6">]</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="o">&gt;</span></code></pre><p>Notice that when calling a local function, there is a difference between using
│ │ │ │  the implicitly or fully qualified function name. The latter always refers to the
│ │ │ │  latest version of the module. See
│ │ │ │  <a href="code_loading.xhtml">Compilation and Code Loading </a>and
│ │ │ │  <a href="ref_man_functions.xhtml#eval">Function Evaluation</a>.</p><h3 id="local-function-names-clashing-with-auto-imported-bifs" class="section-heading">
│ │ │ │    <a href="#local-function-names-clashing-with-auto-imported-bifs" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │ @@ -221,40 +221,40 @@
│ │ │ │  called instead. This is to avoid that future additions to the set of
│ │ │ │  auto-imported BIFs do not silently change the behavior of old code.</p></section><p>However, to avoid that old (pre R14) code changed its behavior when compiled
│ │ │ │  with Erlang/OTP version R14A or later, the following restriction applies: If you
│ │ │ │  override the name of a BIF that was auto-imported in OTP versions prior to R14A
│ │ │ │  (ERTS version 5.8) and have an implicitly qualified call to that function in
│ │ │ │  your code, you either need to explicitly remove the auto-import using a compiler
│ │ │ │  directive, or replace the call with a fully qualified function call. Otherwise
│ │ │ │ -you get a compilation error. See the following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4901230705-1">(</span><span class="p" data-group-id="4901230705-2">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4901230705-2">]</span><span class="p" data-group-id="4901230705-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +you get a compilation error. See the following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1810524008-1">(</span><span class="p" data-group-id="1810524008-2">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1810524008-2">]</span><span class="p" data-group-id="1810524008-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="4901230705-3">(</span><span class="p" data-group-id="4901230705-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="4901230705-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4901230705-5">]</span><span class="p" data-group-id="4901230705-4">}</span><span class="p" data-group-id="4901230705-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="1810524008-3">(</span><span class="p" data-group-id="1810524008-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="1810524008-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1810524008-5">]</span><span class="p" data-group-id="1810524008-4">}</span><span class="p" data-group-id="1810524008-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">length</span><span class="p" data-group-id="4901230705-6">(</span><span class="p" data-group-id="4901230705-7">[</span><span class="p" data-group-id="4901230705-7">]</span><span class="p" data-group-id="4901230705-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">length</span><span class="p" data-group-id="1810524008-6">(</span><span class="p" data-group-id="1810524008-7">[</span><span class="p" data-group-id="1810524008-7">]</span><span class="p" data-group-id="1810524008-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="mi">0</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">length</span><span class="p" data-group-id="4901230705-8">(</span><span class="p" data-group-id="4901230705-9">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4901230705-9">]</span><span class="p" data-group-id="4901230705-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="4901230705-10">(</span><span class="n">T</span><span class="p" data-group-id="4901230705-10">)</span><span class="p">.</span><span class="w"> </span><span class="c1">%% Calls the local function length/1</span><span class="w">
│ │ │ │ +</span><span class="nf">length</span><span class="p" data-group-id="1810524008-8">(</span><span class="p" data-group-id="1810524008-9">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1810524008-9">]</span><span class="p" data-group-id="1810524008-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="1810524008-10">(</span><span class="n">T</span><span class="p" data-group-id="1810524008-10">)</span><span class="p">.</span><span class="w"> </span><span class="c1">%% Calls the local function length/1</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="4901230705-11">(</span><span class="n">X</span><span class="p" data-group-id="4901230705-11">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="4901230705-12">(</span><span class="n">X</span><span class="p" data-group-id="4901230705-12">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="1810524008-11">(</span><span class="n">X</span><span class="p" data-group-id="1810524008-11">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="1810524008-12">(</span><span class="n">X</span><span class="p" data-group-id="1810524008-12">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │ │                                    </span><span class="c1">%% which is allowed in guards</span><span class="w">
│ │ │ │      </span><span class="ss">long</span><span class="p">.</span></code></pre><p>The same logic applies to explicitly imported functions from other modules, as
│ │ │ │  to locally defined functions. It is not allowed to both import a function from
│ │ │ │ -another module and have the function declared in the module at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2029939948-1">(</span><span class="p" data-group-id="2029939948-2">[</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2029939948-2">]</span><span class="p" data-group-id="2029939948-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +another module and have the function declared in the module at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7702284041-1">(</span><span class="p" data-group-id="7702284041-2">[</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7702284041-2">]</span><span class="p" data-group-id="7702284041-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="2029939948-3">(</span><span class="p" data-group-id="2029939948-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="2029939948-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2029939948-5">]</span><span class="p" data-group-id="2029939948-4">}</span><span class="p" data-group-id="2029939948-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="7702284041-3">(</span><span class="p" data-group-id="7702284041-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="7702284041-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7702284041-5">]</span><span class="p" data-group-id="7702284041-4">}</span><span class="p" data-group-id="7702284041-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="2029939948-6">(</span><span class="ss">mod</span><span class="p">,</span><span class="p" data-group-id="2029939948-7">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2029939948-7">]</span><span class="p" data-group-id="2029939948-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="7702284041-6">(</span><span class="ss">mod</span><span class="p">,</span><span class="p" data-group-id="7702284041-7">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7702284041-7">]</span><span class="p" data-group-id="7702284041-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="2029939948-8">(</span><span class="n">X</span><span class="p" data-group-id="2029939948-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="2029939948-9">(</span><span class="n">X</span><span class="p" data-group-id="2029939948-9">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">33</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="7702284041-8">(</span><span class="n">X</span><span class="p" data-group-id="7702284041-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="7702284041-9">(</span><span class="n">X</span><span class="p" data-group-id="7702284041-9">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">33</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │ │                                     </span><span class="c1">%% which is allowed in guards</span><span class="w">
│ │ │ │  
│ │ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="2029939948-10">(</span><span class="n">X</span><span class="p" data-group-id="2029939948-10">)</span><span class="p">;</span><span class="w">              </span><span class="c1">%% Explicit call to erlang:length in body</span><span class="w">
│ │ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="7702284041-10">(</span><span class="n">X</span><span class="p" data-group-id="7702284041-10">)</span><span class="p">;</span><span class="w">              </span><span class="c1">%% Explicit call to erlang:length in body</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="2029939948-11">(</span><span class="n">X</span><span class="p" data-group-id="2029939948-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">length</span><span class="p" data-group-id="2029939948-12">(</span><span class="n">X</span><span class="p" data-group-id="2029939948-12">)</span><span class="p">.</span><span class="w">                     </span><span class="c1">%% mod:length/1 is called</span></code></pre><p>For auto-imported BIFs added in Erlang/OTP R14A and thereafter, overriding the
│ │ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="7702284041-11">(</span><span class="n">X</span><span class="p" data-group-id="7702284041-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">length</span><span class="p" data-group-id="7702284041-12">(</span><span class="n">X</span><span class="p" data-group-id="7702284041-12">)</span><span class="p">.</span><span class="w">                     </span><span class="c1">%% mod:length/1 is called</span></code></pre><p>For auto-imported BIFs added in Erlang/OTP R14A and thereafter, overriding the
│ │ │ │  name with a local function or explicit import is always allowed. However, if the
│ │ │ │  <code class="inline">-compile({no_auto_import,[F/A])</code> directive is not used, the compiler issues a
│ │ │ │  warning whenever the function is called in the module using the implicitly
│ │ │ │  qualified function name.</p><h2 id="if" class="section-heading">
│ │ │ │    <a href="#if" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │ @@ -266,40 +266,40 @@
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="n">GuardSeqN</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>The branches of an <code class="inline">if</code>-expression are scanned sequentially until a guard
│ │ │ │  sequence <code class="inline">GuardSeq</code> that evaluates to true is found. Then the corresponding
│ │ │ │  <code class="inline">Body</code> (a sequence of expressions separated by <code class="inline">,</code>) is evaluated.</p><p>The return value of <code class="inline">Body</code> is the return value of the <code class="inline">if</code> expression.</p><p>If no guard sequence is evaluated as true, an <code class="inline">if_clause</code> run-time error occurs.
│ │ │ │  If necessary, the guard expression <code class="inline">true</code> can be used in the last branch, as
│ │ │ │ -that guard sequence is always true.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_greater_than</span><span class="p" data-group-id="4704618826-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4704618826-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +that guard sequence is always true.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_greater_than</span><span class="p" data-group-id="9086213359-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9086213359-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">if</span><span class="w">
│ │ │ │          </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% works as an &#39;else&#39; branch</span><span class="w">
│ │ │ │              </span><span class="ss">false</span><span class="w">
│ │ │ │      </span><span class="k">end</span></code></pre><h2 id="case" class="section-heading">
│ │ │ │    <a href="#case" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Case</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">Expr</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="4258148758-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="4258148758-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="5521846082-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="5521846082-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="4258148758-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="4258148758-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="5521846082-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="5521846082-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>The expression <code class="inline">Expr</code> is evaluated and the patterns <code class="inline">Pattern</code> are sequentially
│ │ │ │  matched against the result. If a match succeeds and the optional guard sequence
│ │ │ │  <code class="inline">GuardSeq</code> is true, the corresponding <code class="inline">Body</code> is evaluated.</p><p>The return value of <code class="inline">Body</code> is the return value of the <code class="inline">case</code> expression.</p><p>If there is no matching pattern with a true guard sequence, a <code class="inline">case_clause</code>
│ │ │ │ -run-time error occurs.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_valid_signal</span><span class="p" data-group-id="6024743454-1">(</span><span class="n">Signal</span><span class="p" data-group-id="6024743454-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +run-time error occurs.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_valid_signal</span><span class="p" data-group-id="5086940607-1">(</span><span class="n">Signal</span><span class="p" data-group-id="5086940607-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Signal</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6024743454-2">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="6024743454-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5086940607-2">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="5086940607-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6024743454-3">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="6024743454-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5086940607-3">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="5086940607-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="p">_</span><span class="n">Else</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">false</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><h2 id="maybe" class="section-heading">
│ │ │ │    <a href="#maybe" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │ @@ -317,57 +317,57 @@
│ │ │ │  the top-level of a <code class="inline">maybe</code> block. It matches the pattern <code class="inline">Expr1</code> against
│ │ │ │  <code class="inline">Expr2</code>. If the matching succeeds, any unbound variable in the pattern becomes
│ │ │ │  bound. If the expression is the last expression in the <code class="inline">maybe</code> block, it also
│ │ │ │  returns the value of <code class="inline">Expr2</code>. If the matching is unsuccessful, the rest of the
│ │ │ │  expressions in the <code class="inline">maybe</code> block are skipped and the return value of the <code class="inline">maybe</code>
│ │ │ │  block is <code class="inline">Expr2</code>.</p><p>None of the variables bound in a <code class="inline">maybe</code> block must be used in the code that
│ │ │ │  follows the block.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="k">maybe</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3499520834-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="3499520834-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="3499520834-2">(</span><span class="p" data-group-id="3499520834-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2501819511-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="2501819511-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="2501819511-2">(</span><span class="p" data-group-id="2501819511-2">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3499520834-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="3499520834-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="3499520834-4">(</span><span class="p" data-group-id="3499520834-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2501819511-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="2501819511-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="2501819511-4">(</span><span class="p" data-group-id="2501819511-4">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>Let us first assume that <code class="inline">a()</code> returns <code class="inline">{ok,42}</code> and <code class="inline">b()</code> returns <code class="inline">{ok,58}</code>.
│ │ │ │  With those return values, all of the match operators will succeed, and the
│ │ │ │  return value of the <code class="inline">maybe</code> block is <code class="inline">A + B</code>, which is equal to <code class="inline">42 + 58 = 100</code>.</p><p>Now let us assume that <code class="inline">a()</code> returns <code class="inline">error</code>. The conditional match operator in
│ │ │ │  <code class="inline">{ok, A} ?= a()</code> fails to match, and the return value of the <code class="inline">maybe</code> block is
│ │ │ │  the value of the expression that failed to match, namely <code class="inline">error</code>. Similarly, if
│ │ │ │  <code class="inline">b()</code> returns <code class="inline">wrong</code>, the return value of the <code class="inline">maybe</code> block is <code class="inline">wrong</code>.</p><p>Finally, let us assume that <code class="inline">a()</code> returns <code class="inline">{ok,-1}</code>. Because <code class="inline">true = A &gt;= 0</code> uses
│ │ │ │  the match operator <code class="inline">=</code>, a <code class="inline">{badmatch,false}</code> run-time error occurs when the
│ │ │ │ -expression fails to match the pattern.</p><p>The example can be written in a less succient way using nested case expressions:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="8100490301-1">(</span><span class="p" data-group-id="8100490301-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8100490301-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="8100490301-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +expression fails to match the pattern.</p><p>The example can be written in a less succient way using nested case expressions:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="0963589118-1">(</span><span class="p" data-group-id="0963589118-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0963589118-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="0963589118-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="k">case</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="8100490301-3">(</span><span class="p" data-group-id="8100490301-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="8100490301-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="8100490301-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="k">case</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="0963589118-3">(</span><span class="p" data-group-id="0963589118-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="0963589118-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="0963589118-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p">;</span><span class="w">
│ │ │ │              </span><span class="n">Other1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                  </span><span class="n">Other1</span><span class="w">
│ │ │ │          </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="n">Other2</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">Other2</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>The <code class="inline">maybe</code> block can be augmented with <code class="inline">else</code> clauses:</p><pre><code class="makeup erlang" translate="no"><span class="k">maybe</span><span class="w">
│ │ │ │      </span><span class="n">Expr1</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="n">ExprN</span><span class="w">
│ │ │ │  </span><span class="k">else</span><span class="w">
│ │ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="2525260424-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="2525260424-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="1620614708-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="1620614708-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="2525260424-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="2525260424-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="1620614708-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="1620614708-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>If a conditional match operator fails, the failed expression is matched against
│ │ │ │  the patterns in all clauses between the <code class="inline">else</code> and <code class="inline">end</code> keywords. If a match
│ │ │ │  succeeds and the optional guard sequence <code class="inline">GuardSeq</code> is true, the corresponding
│ │ │ │  <code class="inline">Body</code> is evaluated. The value returned from the body is the return value of the
│ │ │ │  <code class="inline">maybe</code> block.</p><p>If there is no matching pattern with a true guard sequence, an <code class="inline">else_clause</code>
│ │ │ │  run-time error occurs.</p><p>None of the variables bound in a <code class="inline">maybe</code> block must be used in the <code class="inline">else</code>
│ │ │ │  clauses. None of the variables bound in the <code class="inline">else</code> clauses must be used in the
│ │ │ │  code that follows the <code class="inline">maybe</code> block.</p><p>Here is the previous example augmented with <code class="inline">else</code> clauses:</p><pre><code class="makeup erlang" translate="no"><span class="k">maybe</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9879775903-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="9879775903-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="9879775903-2">(</span><span class="p" data-group-id="9879775903-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3751300399-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="3751300399-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="3751300399-2">(</span><span class="p" data-group-id="3751300399-2">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9879775903-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="9879775903-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="9879775903-4">(</span><span class="p" data-group-id="9879775903-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3751300399-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="3751300399-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="3751300399-4">(</span><span class="p" data-group-id="3751300399-4">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="w">
│ │ │ │  </span><span class="k">else</span><span class="w">
│ │ │ │      </span><span class="ss">error</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">error</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="ss">wrong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">error</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>The <code class="inline">else</code> clauses translate the failing value from the conditional match
│ │ │ │  operators to the value <code class="inline">error</code>. If the failing value is not one of the
│ │ │ │  recognized values, a <code class="inline">else_clause</code> run-time error occurs.</p><h2 id="send" class="section-heading">
│ │ │ │ @@ -386,75 +386,75 @@
│ │ │ │  <code class="inline">{Name,Node}</code> (or a pid located at another node), also never fails.</li></ul><h2 id="receive" class="section-heading">
│ │ │ │    <a href="#receive" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Receive</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="4222810086-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="4222810086-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="8542659015-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="8542659015-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="4222810086-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="4222810086-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="8542659015-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="8542659015-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>Fetches a received message present in the message queue of the process. The
│ │ │ │  first message in the message queue is matched sequentially against the patterns
│ │ │ │  from top to bottom. If no match was found, the matching sequence is repeated for
│ │ │ │  the second message in the queue, and so on. Messages are queued in the
│ │ │ │  <a href="ref_man_processes.xhtml#message-queue-order">order they were received</a>. If a match
│ │ │ │  succeeds, that is, if the <code class="inline">Pattern</code> matches and the optional guard sequence
│ │ │ │  <code class="inline">GuardSeq</code> is true, then the message is removed from the message queue and the
│ │ │ │  corresponding <code class="inline">Body</code> is evaluated. All other messages in the message queue
│ │ │ │  remain unchanged.</p><p>The return value of <code class="inline">Body</code> is the return value of the <code class="inline">receive</code> expression.</p><p><code class="inline">receive</code> never fails. The execution is suspended, possibly indefinitely, until
│ │ │ │  a message arrives that matches one of the patterns and with a true guard
│ │ │ │ -sequence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="7641844204-1">(</span><span class="p" data-group-id="7641844204-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +sequence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="3898622986-1">(</span><span class="p" data-group-id="3898622986-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">onhook</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">disconnect</span><span class="p" data-group-id="7641844204-2">(</span><span class="p" data-group-id="7641844204-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">idle</span><span class="p" data-group-id="7641844204-3">(</span><span class="p" data-group-id="7641844204-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="7641844204-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="7641844204-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7641844204-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7641844204-6">(</span><span class="p" data-group-id="7641844204-6">)</span><span class="p" data-group-id="7641844204-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="7641844204-7">(</span><span class="p" data-group-id="7641844204-7">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">disconnect</span><span class="p" data-group-id="3898622986-2">(</span><span class="p" data-group-id="3898622986-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">idle</span><span class="p" data-group-id="3898622986-3">(</span><span class="p" data-group-id="3898622986-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="3898622986-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="3898622986-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3898622986-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3898622986-6">(</span><span class="p" data-group-id="3898622986-6">)</span><span class="p" data-group-id="3898622986-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="3898622986-7">(</span><span class="p" data-group-id="3898622986-7">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">receive</code> expression can be augmented with a timeout:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="6299348752-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="6299348752-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="4273323277-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="4273323277-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="6299348752-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="6299348752-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="4273323277-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="4273323277-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │ │  </span><span class="k">after</span><span class="w">
│ │ │ │      </span><span class="n">ExprT</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyT</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p><code class="inline">receive...after</code> works exactly as <code class="inline">receive</code>, except that if no matching message
│ │ │ │  has arrived within <code class="inline">ExprT</code> milliseconds, then <code class="inline">BodyT</code> is evaluated instead. The
│ │ │ │  return value of <code class="inline">BodyT</code> then becomes the return value of the <code class="inline">receive...after</code>
│ │ │ │  expression. <code class="inline">ExprT</code> is to evaluate to an integer, or the atom <code class="inline">infinity</code>. The
│ │ │ │  allowed integer range is from 0 to 4294967295, that is, the longest possible
│ │ │ │  timeout is almost 50 days. With a zero value the timeout occurs immediately if
│ │ │ │  there is no matching message in the message queue.</p><p>The atom <code class="inline">infinity</code> will make the process wait indefinitely for a matching
│ │ │ │  message. This is the same as not using a timeout. It can be useful for timeout
│ │ │ │ -values that are calculated at runtime.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="6406967664-1">(</span><span class="p" data-group-id="6406967664-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +values that are calculated at runtime.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="1264908435-1">(</span><span class="p" data-group-id="1264908435-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">onhook</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">disconnect</span><span class="p" data-group-id="6406967664-2">(</span><span class="p" data-group-id="6406967664-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">idle</span><span class="p" data-group-id="6406967664-3">(</span><span class="p" data-group-id="6406967664-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6406967664-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="6406967664-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6406967664-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6406967664-6">(</span><span class="p" data-group-id="6406967664-6">)</span><span class="p" data-group-id="6406967664-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="6406967664-7">(</span><span class="p" data-group-id="6406967664-7">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">disconnect</span><span class="p" data-group-id="1264908435-2">(</span><span class="p" data-group-id="1264908435-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">idle</span><span class="p" data-group-id="1264908435-3">(</span><span class="p" data-group-id="1264908435-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="1264908435-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="1264908435-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1264908435-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1264908435-6">(</span><span class="p" data-group-id="1264908435-6">)</span><span class="p" data-group-id="1264908435-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="1264908435-7">(</span><span class="p" data-group-id="1264908435-7">)</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w">
│ │ │ │          </span><span class="mi">60000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">disconnect</span><span class="p" data-group-id="6406967664-8">(</span><span class="p" data-group-id="6406967664-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">error</span><span class="p" data-group-id="6406967664-9">(</span><span class="p" data-group-id="6406967664-9">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">disconnect</span><span class="p" data-group-id="1264908435-8">(</span><span class="p" data-group-id="1264908435-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">error</span><span class="p" data-group-id="1264908435-9">(</span><span class="p" data-group-id="1264908435-9">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>It is legal to use a <code class="inline">receive...after</code> expression with no branches:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │  </span><span class="k">after</span><span class="w">
│ │ │ │      </span><span class="n">ExprT</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyT</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>This construction does not consume any messages, only suspends execution in the
│ │ │ │ -process for <code class="inline">ExprT</code> milliseconds. This can be used to implement simple timers.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">timer</span><span class="p" data-group-id="2735163105-1">(</span><span class="p" data-group-id="2735163105-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="2735163105-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2735163105-3">[</span><span class="nf">self</span><span class="p" data-group-id="2735163105-4">(</span><span class="p" data-group-id="2735163105-4">)</span><span class="p" data-group-id="2735163105-3">]</span><span class="p" data-group-id="2735163105-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +process for <code class="inline">ExprT</code> milliseconds. This can be used to implement simple timers.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">timer</span><span class="p" data-group-id="7982109658-1">(</span><span class="p" data-group-id="7982109658-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7982109658-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7982109658-3">[</span><span class="nf">self</span><span class="p" data-group-id="7982109658-4">(</span><span class="p" data-group-id="7982109658-4">)</span><span class="p" data-group-id="7982109658-3">]</span><span class="p" data-group-id="7982109658-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">timer</span><span class="p" data-group-id="2735163105-5">(</span><span class="n">Pid</span><span class="p" data-group-id="2735163105-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">timer</span><span class="p" data-group-id="7982109658-5">(</span><span class="n">Pid</span><span class="p" data-group-id="7982109658-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w">
│ │ │ │          </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">timeout</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>For more information on timers in Erlang in general, see the
│ │ │ │  <a href="../../../lib/../erts/doc/html/time_correction.xhtml#timers"><em>Timers</em></a> section of the
│ │ │ │  <a href="../../../lib/../erts/doc/html/time_correction.xhtml"><em>Time and Time Correction in Erlang</em></a>
│ │ │ │ @@ -496,21 +496,21 @@
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │  4&gt; </span><span class="mf">0.0</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">-</span><span class="mf">0.0</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │  5&gt; </span><span class="mf">0.0</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">+</span><span class="mf">0.0</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │  6&gt; </span><span class="mi">1</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │ -7&gt; </span><span class="p" data-group-id="8805042462-1">#{</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="8805042462-1">}</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="8805042462-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="8805042462-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +7&gt; </span><span class="p" data-group-id="1441865613-1">#{</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1441865613-1">}</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="1441865613-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="1441865613-2">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │ -8&gt; </span><span class="p" data-group-id="8805042462-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="8805042462-3">}</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="p" data-group-id="8805042462-4">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">2.0</span><span class="p" data-group-id="8805042462-4">}</span><span class="p">.</span><span class="w">
│ │ │ │ +8&gt; </span><span class="p" data-group-id="1441865613-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="1441865613-3">}</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="p" data-group-id="1441865613-4">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">2.0</span><span class="p" data-group-id="1441865613-4">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -9&gt; </span><span class="p" data-group-id="8805042462-5">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="8805042462-5">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="8805042462-6">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="8805042462-6">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +9&gt; </span><span class="p" data-group-id="1441865613-5">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="1441865613-5">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="1441865613-6">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="1441865613-6">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -10&gt; </span><span class="p" data-group-id="8805042462-7">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="8805042462-7">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="8805042462-8">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="8805042462-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +10&gt; </span><span class="p" data-group-id="1441865613-7">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="1441865613-7">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="1441865613-8">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="1441865613-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Prior to OTP 27, the term equivalence operators considered <code class="inline">0.0</code>
│ │ │ │  and <code class="inline">-0.0</code> to be the same term.</p><p>This was changed in OTP 27 but legacy code may have expected them to be
│ │ │ │  considered the same. To help users catch errors that may arise from an
│ │ │ │  upgrade, the compiler raises a warning when <code class="inline">0.0</code> is pattern-matched or used
│ │ │ │  in a term equivalence test.</p><p>If you need to match <code class="inline">0.0</code> specifically, the warning can be silenced by
│ │ │ │  writing <code class="inline">+0.0</code> instead, which produces the same term but makes the compiler
│ │ │ │  interpret the match as being done on purpose.</p></section><h2 id="arithmetic-expressions" class="section-heading">
│ │ │ │ @@ -536,15 +536,15 @@
│ │ │ │  </span><span class="mi">0</span><span class="gp unselectable">
│ │ │ │  8&gt; </span><span class="mi">2#10</span><span class="w"> </span><span class="ow">bor</span><span class="w"> </span><span class="mi">2#01</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │  9&gt; </span><span class="ss">a</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">10</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: an error occurred when evaluating an arithmetic expression
│ │ │ │       in operator  +/2
│ │ │ │          called as a + 10</span><span class="gp unselectable">
│ │ │ │ -10&gt; </span><span class="mi">1</span><span class="w"> </span><span class="nf">bsl</span><span class="w"> </span><span class="p" data-group-id="4201915929-1">(</span><span class="mi">1</span><span class="w"> </span><span class="ow">bsl</span><span class="w"> </span><span class="mi">64</span><span class="p" data-group-id="4201915929-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +10&gt; </span><span class="mi">1</span><span class="w"> </span><span class="nf">bsl</span><span class="w"> </span><span class="p" data-group-id="3882057907-1">(</span><span class="mi">1</span><span class="w"> </span><span class="ow">bsl</span><span class="w"> </span><span class="mi">64</span><span class="p" data-group-id="3882057907-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: a system limit has been reached
│ │ │ │       in operator  bsl/2
│ │ │ │          called as 1 bsl 18446744073709551616</span></code></pre><h2 id="boolean-expressions" class="section-heading">
│ │ │ │    <a href="#boolean-expressions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Boolean Expressions</span>
│ │ │ │ @@ -563,136 +563,136 @@
│ │ │ │    <a href="#short-circuit-expressions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Short-Circuit Expressions</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="n">Expr1</span><span class="w"> </span><span class="ow">orelse</span><span class="w"> </span><span class="n">Expr2</span><span class="w">
│ │ │ │  </span><span class="n">Expr1</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">Expr2</span></code></pre><p><code class="inline">Expr2</code> is evaluated only if necessary. That is, <code class="inline">Expr2</code> is evaluated only if:</p><ul><li><code class="inline">Expr1</code> evaluates to <code class="inline">false</code> in an <code class="inline">orelse</code> expression.</li></ul><p>or</p><ul><li><code class="inline">Expr1</code> evaluates to <code class="inline">true</code> in an <code class="inline">andalso</code> expression.</li></ul><p>Returns either the value of <code class="inline">Expr1</code> (that is, <code class="inline">true</code> or <code class="inline">false</code>) or the value of
│ │ │ │ -<code class="inline">Expr2</code> (if <code class="inline">Expr2</code> is evaluated).</p><p><em>Example 1:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="o">-</span><span class="mf">1.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nc">math</span><span class="p">:</span><span class="nf">sqrt</span><span class="p" data-group-id="0747666942-1">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="0747666942-1">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="k">of</span></code></pre><p>This works even if <code class="inline">A</code> is less than <code class="inline">-1.0</code>, since in that case, <a href="../../../lib/stdlib/doc/html/math.html#sqrt/1"><code class="inline">math:sqrt/1</code></a> is
│ │ │ │ -never evaluated.</p><p><em>Example 2:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">OnlyOne</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">is_atom</span><span class="p" data-group-id="4398997202-1">(</span><span class="n">L</span><span class="p" data-group-id="4398997202-1">)</span><span class="w"> </span><span class="nf">orelse</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="4398997202-2">(</span><span class="nf">is_list</span><span class="p" data-group-id="4398997202-3">(</span><span class="n">L</span><span class="p" data-group-id="4398997202-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="4398997202-4">(</span><span class="n">L</span><span class="p" data-group-id="4398997202-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4398997202-2">)</span><span class="p">,</span></code></pre><p><code class="inline">Expr2</code> is not required to evaluate to a Boolean value. Because of that,
│ │ │ │ -<code class="inline">andalso</code> and <code class="inline">orelse</code> are tail-recursive.</p><p><em>Example 3 (tail-recursive function):</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="3393212801-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3393212801-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="3393212801-2">]</span><span class="p" data-group-id="3393212801-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Pred</span><span class="p" data-group-id="3393212801-3">(</span><span class="n">Hd</span><span class="p" data-group-id="3393212801-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">all</span><span class="p" data-group-id="3393212801-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="3393212801-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">all</span><span class="p" data-group-id="3393212801-5">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3393212801-6">[</span><span class="p" data-group-id="3393212801-6">]</span><span class="p" data-group-id="3393212801-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +<code class="inline">Expr2</code> (if <code class="inline">Expr2</code> is evaluated).</p><p><em>Example 1:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="o">-</span><span class="mf">1.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nc">math</span><span class="p">:</span><span class="nf">sqrt</span><span class="p" data-group-id="0350098467-1">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="0350098467-1">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="k">of</span></code></pre><p>This works even if <code class="inline">A</code> is less than <code class="inline">-1.0</code>, since in that case, <a href="../../../lib/stdlib/doc/html/math.html#sqrt/1"><code class="inline">math:sqrt/1</code></a> is
│ │ │ │ +never evaluated.</p><p><em>Example 2:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">OnlyOne</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">is_atom</span><span class="p" data-group-id="0294915576-1">(</span><span class="n">L</span><span class="p" data-group-id="0294915576-1">)</span><span class="w"> </span><span class="nf">orelse</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="0294915576-2">(</span><span class="nf">is_list</span><span class="p" data-group-id="0294915576-3">(</span><span class="n">L</span><span class="p" data-group-id="0294915576-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="0294915576-4">(</span><span class="n">L</span><span class="p" data-group-id="0294915576-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="0294915576-2">)</span><span class="p">,</span></code></pre><p><code class="inline">Expr2</code> is not required to evaluate to a Boolean value. Because of that,
│ │ │ │ +<code class="inline">andalso</code> and <code class="inline">orelse</code> are tail-recursive.</p><p><em>Example 3 (tail-recursive function):</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="6946687490-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6946687490-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="6946687490-2">]</span><span class="p" data-group-id="6946687490-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pred</span><span class="p" data-group-id="6946687490-3">(</span><span class="n">Hd</span><span class="p" data-group-id="6946687490-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">all</span><span class="p" data-group-id="6946687490-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="6946687490-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">all</span><span class="p" data-group-id="6946687490-5">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6946687490-6">[</span><span class="p" data-group-id="6946687490-6">]</span><span class="p" data-group-id="6946687490-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">true</span><span class="p">.</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP R13A, <code class="inline">Expr2</code> was required to evaluate to a Boolean value,
│ │ │ │  and as consequence, <code class="inline">andalso</code> and <code class="inline">orelse</code> were <strong>not</strong> tail-recursive.</p></section><h2 id="list-operations" class="section-heading">
│ │ │ │    <a href="#list-operations" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">List Operations</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="n">Expr1</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Expr2</span><span class="w">
│ │ │ │  </span><span class="n">Expr1</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="n">Expr2</span></code></pre><p>The list concatenation operator <code class="inline">++</code> appends its second argument to its first
│ │ │ │  and returns the resulting list.</p><p>The list subtraction operator <code class="inline">--</code> produces a list that is a copy of the first
│ │ │ │  argument. The procedure is as follows: for each element in the second argument,
│ │ │ │ -the first occurrence of this element (if any) is removed.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4704400008-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4704400008-1">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="4704400008-2">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4704400008-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4704400008-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4704400008-3">]</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="4704400008-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4704400008-4">]</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="p" data-group-id="4704400008-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4704400008-5">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4704400008-6">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4704400008-6">]</span></code></pre><h2 id="map-expressions" class="section-heading">
│ │ │ │ +the first occurrence of this element (if any) is removed.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="1507773518-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1507773518-1">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="1507773518-2">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="1507773518-2">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1507773518-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="1507773518-3">]</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="1507773518-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1507773518-4">]</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="p" data-group-id="1507773518-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1507773518-5">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1507773518-6">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1507773518-6">]</span></code></pre><h2 id="map-expressions" class="section-heading">
│ │ │ │    <a href="#map-expressions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Map Expressions</span>
│ │ │ │  </h2>
│ │ │ │  <h3 id="creating-maps" class="section-heading">
│ │ │ │    <a href="#creating-maps" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Creating Maps</span>
│ │ │ │  </h3>
│ │ │ │  <p>Constructing a new map is done by letting an expression <code class="inline">K</code> be associated with
│ │ │ │ -another expression <code class="inline">V</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5837183994-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="5837183994-1">}</span></code></pre><p>New maps can include multiple associations at construction by listing every
│ │ │ │ -association:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6721271374-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="6721271374-1">}</span></code></pre><p>An empty map is constructed by not associating any terms with each other:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3819125369-1">#{</span><span class="p" data-group-id="3819125369-1">}</span></code></pre><p>All keys and values in the map are terms. Any expression is first evaluated and
│ │ │ │ +another expression <code class="inline">V</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2619719730-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="2619719730-1">}</span></code></pre><p>New maps can include multiple associations at construction by listing every
│ │ │ │ +association:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0084513366-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="0084513366-1">}</span></code></pre><p>An empty map is constructed by not associating any terms with each other:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5995979581-1">#{</span><span class="p" data-group-id="5995979581-1">}</span></code></pre><p>All keys and values in the map are terms. Any expression is first evaluated and
│ │ │ │  then the resulting terms are used as <em>key</em> and <em>value</em> respectively.</p><p>Keys and values are separated by the <code class="inline">=&gt;</code> arrow and associations are separated
│ │ │ │ -by a comma (<code class="inline">,</code>).</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2431863374-1">#{</span><span class="p" data-group-id="2431863374-1">}</span><span class="p">,</span><span class="w">                 </span><span class="c1">% empty map</span><span class="w">
│ │ │ │ -</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2431863374-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2431863374-3">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="2431863374-3">&gt;&gt;</span><span class="p" data-group-id="2431863374-2">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% single association with literals</span><span class="w">
│ │ │ │ -</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2431863374-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2431863374-4">}</span><span class="p">,</span><span class="w">   </span><span class="c1">% multiple associations with literals</span><span class="w">
│ │ │ │ -</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2431863374-5">#{</span><span class="ss">k</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2431863374-6">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="2431863374-6">}</span><span class="p" data-group-id="2431863374-5">}</span><span class="p">,</span><span class="w">       </span><span class="c1">% single association with variables</span><span class="w">
│ │ │ │ -</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2431863374-7">#{</span><span class="p" data-group-id="2431863374-8">{</span><span class="s">&quot;w&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="2431863374-8">}</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="2431863374-9">(</span><span class="p" data-group-id="2431863374-9">)</span><span class="p" data-group-id="2431863374-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% compound key associated with an evaluated expression</span></code></pre><p>Here, <code class="inline">A</code> and <code class="inline">B</code> are any expressions and <code class="inline">M0</code> through <code class="inline">M4</code> are the resulting
│ │ │ │ -map terms.</p><p>If two matching keys are declared, the latter key takes precedence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4276103601-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="4276103601-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4276103601-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p" data-group-id="4276103601-2">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="4276103601-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="4276103601-3">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4276103601-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="4276103601-4">}</span></code></pre><p>The order in which the expressions constructing the keys (and their associated
│ │ │ │ +by a comma (<code class="inline">,</code>).</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2353067305-1">#{</span><span class="p" data-group-id="2353067305-1">}</span><span class="p">,</span><span class="w">                 </span><span class="c1">% empty map</span><span class="w">
│ │ │ │ +</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2353067305-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2353067305-3">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="2353067305-3">&gt;&gt;</span><span class="p" data-group-id="2353067305-2">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% single association with literals</span><span class="w">
│ │ │ │ +</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2353067305-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2353067305-4">}</span><span class="p">,</span><span class="w">   </span><span class="c1">% multiple associations with literals</span><span class="w">
│ │ │ │ +</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2353067305-5">#{</span><span class="ss">k</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2353067305-6">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="2353067305-6">}</span><span class="p" data-group-id="2353067305-5">}</span><span class="p">,</span><span class="w">       </span><span class="c1">% single association with variables</span><span class="w">
│ │ │ │ +</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2353067305-7">#{</span><span class="p" data-group-id="2353067305-8">{</span><span class="s">&quot;w&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="2353067305-8">}</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="2353067305-9">(</span><span class="p" data-group-id="2353067305-9">)</span><span class="p" data-group-id="2353067305-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% compound key associated with an evaluated expression</span></code></pre><p>Here, <code class="inline">A</code> and <code class="inline">B</code> are any expressions and <code class="inline">M0</code> through <code class="inline">M4</code> are the resulting
│ │ │ │ +map terms.</p><p>If two matching keys are declared, the latter key takes precedence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7125495355-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="7125495355-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7125495355-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p" data-group-id="7125495355-2">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="7125495355-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="7125495355-3">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7125495355-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="7125495355-4">}</span></code></pre><p>The order in which the expressions constructing the keys (and their associated
│ │ │ │  values) are evaluated is not defined. The syntactic order of the key-value pairs
│ │ │ │  in the construction is of no relevance, except in the recently mentioned case of
│ │ │ │  two matching keys.</p><h3 id="updating-maps" class="section-heading">
│ │ │ │    <a href="#updating-maps" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Updating Maps</span>
│ │ │ │  </h3>
│ │ │ │  <p>Updating a map has a similar syntax as constructing it.</p><p>An expression defining the map to be updated is put in front of the expression
│ │ │ │ -defining the keys to be updated and their respective values:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="6092015561-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="6092015561-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map and <code class="inline">K</code> and <code class="inline">V</code> are any expression.</p><p>If key <code class="inline">K</code> does not match any existing key in the map, a new association is
│ │ │ │ +defining the keys to be updated and their respective values:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="6158886927-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="6158886927-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map and <code class="inline">K</code> and <code class="inline">V</code> are any expression.</p><p>If key <code class="inline">K</code> does not match any existing key in the map, a new association is
│ │ │ │  created from key <code class="inline">K</code> to value <code class="inline">V</code>.</p><p>If key <code class="inline">K</code> matches an existing key in map <code class="inline">M</code>, its associated value is replaced
│ │ │ │  by the new value <code class="inline">V</code>. In both cases, the evaluated map expression returns a new
│ │ │ │ -map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p>To only update an existing value, the following syntax is used:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="0267913471-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="0267913471-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map, <code class="inline">V</code> is an expression and <code class="inline">K</code> is an expression
│ │ │ │ +map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p>To only update an existing value, the following syntax is used:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="9374871576-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="9374871576-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map, <code class="inline">V</code> is an expression and <code class="inline">K</code> is an expression
│ │ │ │  that evaluates to an existing key in <code class="inline">M</code>.</p><p>If key <code class="inline">K</code> does not match any existing keys in map <code class="inline">M</code>, an exception of type
│ │ │ │  <code class="inline">badkey</code> is raised at runtime. If a matching key <code class="inline">K</code> is present in map <code class="inline">M</code>,
│ │ │ │  its associated value is replaced by the new value <code class="inline">V</code>, and the evaluated map
│ │ │ │ -expression returns a new map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3389065652-1">#{</span><span class="p" data-group-id="3389065652-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M0</span><span class="p" data-group-id="3389065652-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3389065652-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="3389065652-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3389065652-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M2</span><span class="p" data-group-id="3389065652-4">#{</span><span class="s">&quot;function&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3389065652-5">(</span><span class="p" data-group-id="3389065652-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="3389065652-6">(</span><span class="p" data-group-id="3389065652-6">)</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="3389065652-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M3</span><span class="p" data-group-id="3389065652-7">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="3389065652-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% &#39;a&#39; and &#39;b&#39; was added in `M1` and `M2`.</span></code></pre><p>Here <code class="inline">M0</code> is any map. It follows that <code class="inline">M1</code> through <code class="inline">M4</code> are maps as well.</p><p><em>More examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0586100620-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="0586100620-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0586100620-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="p" data-group-id="0586100620-2">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="n">M</span><span class="p" data-group-id="0586100620-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="0586100620-3">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0586100620-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="0586100620-4">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="n">M</span><span class="p" data-group-id="0586100620-5">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="0586100620-5">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0586100620-6">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="0586100620-6">}</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="n">M</span><span class="p" data-group-id="0586100620-7">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="0586100620-7">}</span><span class="p">.</span><span class="w">
│ │ │ │ +expression returns a new map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4402209825-1">#{</span><span class="p" data-group-id="4402209825-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M0</span><span class="p" data-group-id="4402209825-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4402209825-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="4402209825-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="4402209825-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M2</span><span class="p" data-group-id="4402209825-4">#{</span><span class="s">&quot;function&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4402209825-5">(</span><span class="p" data-group-id="4402209825-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="4402209825-6">(</span><span class="p" data-group-id="4402209825-6">)</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="4402209825-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M3</span><span class="p" data-group-id="4402209825-7">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="4402209825-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% &#39;a&#39; and &#39;b&#39; was added in `M1` and `M2`.</span></code></pre><p>Here <code class="inline">M0</code> is any map. It follows that <code class="inline">M1</code> through <code class="inline">M4</code> are maps as well.</p><p><em>More examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2095631914-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="2095631914-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2095631914-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="p" data-group-id="2095631914-2">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="n">M</span><span class="p" data-group-id="2095631914-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2095631914-3">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2095631914-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2095631914-4">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ │ +3&gt; </span><span class="n">M</span><span class="p" data-group-id="2095631914-5">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2095631914-5">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2095631914-6">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2095631914-6">}</span><span class="gp unselectable">
│ │ │ │ +4&gt; </span><span class="n">M</span><span class="p" data-group-id="2095631914-7">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2095631914-7">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: bad argument</span></code></pre><p>As in construction, the order in which the key and value expressions are
│ │ │ │  evaluated is not defined. The syntactic order of the key-value pairs in the
│ │ │ │  update is of no relevance, except in the case where two keys match. In that
│ │ │ │  case, the latter value is used.</p><h3 id="maps-in-patterns" class="section-heading">
│ │ │ │    <a href="#maps-in-patterns" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Maps in Patterns</span>
│ │ │ │  </h3>
│ │ │ │ -<p>Matching of key-value associations from maps is done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0961462966-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="0961462966-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here <code class="inline">M</code> is any map. The key <code class="inline">K</code> must be a
│ │ │ │ +<p>Matching of key-value associations from maps is done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1176767653-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="1176767653-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here <code class="inline">M</code> is any map. The key <code class="inline">K</code> must be a
│ │ │ │  <a href="expressions.xhtml#guard-expressions">guard expression</a>, with all variables already
│ │ │ │  bound. <code class="inline">V</code> can be any pattern with either bound or unbound variables.</p><p>If the variable <code class="inline">V</code> is unbound, it becomes bound to the value associated with
│ │ │ │  the key <code class="inline">K</code>, which must exist in the map <code class="inline">M</code>. If the variable <code class="inline">V</code> is bound, it
│ │ │ │  must match the value associated with <code class="inline">K</code> in <code class="inline">M</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 23, the expression defining the key <code class="inline">K</code> was restricted to be
│ │ │ │ -either a single variable or a literal.</p></section><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9055843701-1">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9055843701-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9055843701-2">}</span><span class="p" data-group-id="9055843701-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9055843701-3">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9055843701-4">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9055843701-4">}</span><span class="p" data-group-id="9055843701-3">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="9055843701-5">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9055843701-6">{</span><span class="mi">1</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="9055843701-6">}</span><span class="p" data-group-id="9055843701-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9055843701-7">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9055843701-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9055843701-8">}</span><span class="p" data-group-id="9055843701-7">}</span><span class="gp unselectable">
│ │ │ │ +either a single variable or a literal.</p></section><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4315645719-1">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4315645719-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4315645719-2">}</span><span class="p" data-group-id="4315645719-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4315645719-3">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4315645719-4">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4315645719-4">}</span><span class="p" data-group-id="4315645719-3">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="4315645719-5">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="4315645719-6">{</span><span class="mi">1</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="4315645719-6">}</span><span class="p" data-group-id="4315645719-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4315645719-7">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4315645719-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4315645719-8">}</span><span class="p" data-group-id="4315645719-7">}</span><span class="gp unselectable">
│ │ │ │  3&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="mi">2</span><span class="p">.</span></code></pre><p>This binds variable <code class="inline">B</code> to integer <code class="inline">2</code>.</p><p>Similarly, multiple values from the map can be matched:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1562251374-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="1562251374-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here keys <code class="inline">K1</code> through <code class="inline">Kn</code> are any expressions with literals or bound
│ │ │ │ +</span><span class="mi">2</span><span class="p">.</span></code></pre><p>This binds variable <code class="inline">B</code> to integer <code class="inline">2</code>.</p><p>Similarly, multiple values from the map can be matched:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1656601447-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="1656601447-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here keys <code class="inline">K1</code> through <code class="inline">Kn</code> are any expressions with literals or bound
│ │ │ │  variables. If all key expressions evaluate successfully and all keys
│ │ │ │  exist in map <code class="inline">M</code>, all variables in <code class="inline">V1 .. Vn</code> is matched to the
│ │ │ │  associated values of their respective keys.</p><p>If the matching conditions are not met the match fails.</p><p>Note that when matching a map, only the <code class="inline">:=</code> operator (not the <code class="inline">=&gt;</code>) is allowed
│ │ │ │  as a delimiter for the associations.</p><p>The order in which keys are declared in matching has no relevance.</p><p>Duplicate keys are allowed in matching and match each pattern associated to the
│ │ │ │ -keys:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9405970494-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V2</span><span class="p" data-group-id="9405970494-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>The empty map literal (<code class="inline">#{}</code>) matches any map when used as a pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3803789382-1">#{</span><span class="p" data-group-id="3803789382-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>This expression matches if the expression <code class="inline">Expr</code> is of type map, otherwise it
│ │ │ │ -fails with an exception <code class="inline">badmatch</code>.</p><p>Here the key to be retrieved is constructed from an expression:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6661828598-1">#{</span><span class="p" data-group-id="6661828598-2">{</span><span class="ss">tag</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="6661828598-3">(</span><span class="n">List</span><span class="p" data-group-id="6661828598-3">)</span><span class="p" data-group-id="6661828598-2">}</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="6661828598-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map</span></code></pre><p><code class="inline">List</code> must be an already bound variable.</p><h4>Matching Syntax</h4><p>Matching of literals as keys are allowed in function heads:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% only start if not_started</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="7338234444-1">(</span><span class="ss">start</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7338234444-2">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">not_started</span><span class="p" data-group-id="7338234444-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="7338234444-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +keys:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9084970220-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V2</span><span class="p" data-group-id="9084970220-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>The empty map literal (<code class="inline">#{}</code>) matches any map when used as a pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1613499781-1">#{</span><span class="p" data-group-id="1613499781-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>This expression matches if the expression <code class="inline">Expr</code> is of type map, otherwise it
│ │ │ │ +fails with an exception <code class="inline">badmatch</code>.</p><p>Here the key to be retrieved is constructed from an expression:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5354548387-1">#{</span><span class="p" data-group-id="5354548387-2">{</span><span class="ss">tag</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="5354548387-3">(</span><span class="n">List</span><span class="p" data-group-id="5354548387-3">)</span><span class="p" data-group-id="5354548387-2">}</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="5354548387-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map</span></code></pre><p><code class="inline">List</code> must be an already bound variable.</p><h4>Matching Syntax</h4><p>Matching of literals as keys are allowed in function heads:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% only start if not_started</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="8563953477-1">(</span><span class="ss">start</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8563953477-2">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">not_started</span><span class="p" data-group-id="8563953477-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8563953477-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7338234444-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="7338234444-4">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="7338234444-4">}</span><span class="p" data-group-id="7338234444-3">}</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8563953477-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8563953477-4">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="8563953477-4">}</span><span class="p" data-group-id="8563953477-3">}</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% only change if started</span><span class="w">
│ │ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="7338234444-5">(</span><span class="ss">change</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7338234444-6">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="7338234444-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="7338234444-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="8563953477-5">(</span><span class="ss">change</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8563953477-6">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="8563953477-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8563953477-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7338234444-7">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="7338234444-8">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">changed</span><span class="p" data-group-id="7338234444-8">}</span><span class="p" data-group-id="7338234444-7">}</span><span class="p">;</span></code></pre><h3 id="maps-in-guards" class="section-heading">
│ │ │ │ +    </span><span class="p" data-group-id="8563953477-7">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8563953477-8">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">changed</span><span class="p" data-group-id="8563953477-8">}</span><span class="p" data-group-id="8563953477-7">}</span><span class="p">;</span></code></pre><h3 id="maps-in-guards" class="section-heading">
│ │ │ │    <a href="#maps-in-guards" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Maps in Guards</span>
│ │ │ │  </h3>
│ │ │ │  <p>Maps are allowed in guards as long as all subexpressions are valid guard
│ │ │ │  expressions.</p><p>The following guard BIFs handle maps:</p><ul><li><a href="../../../lib/../erts/doc/html/erlang.html#is_map/1">is_map/1</a> in the <code class="inline">erlang</code> module</li><li><a href="../../../lib/../erts/doc/html/erlang.html#is_map_key/2">is_map_key/2</a> in the <code class="inline">erlang</code> module</li><li><a href="../../../lib/../erts/doc/html/erlang.html#map_get/2">map_get/2</a> in the <code class="inline">erlang</code> module</li><li><a href="../../../lib/../erts/doc/html/erlang.html#map_size/1">map_size/1</a> in the <code class="inline">erlang</code> module</li></ul><h2 id="bit-syntax-expressions" class="section-heading">
│ │ │ │    <a href="#bit-syntax-expressions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Bit Syntax Expressions</span>
│ │ │ │  </h2>
│ │ │ │  <p>The bit syntax operates on <em>bit strings</em>. A bit string is a sequence of bits
│ │ │ │ -ordered from the most significant bit to the least significant bit.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4289618789-1">&lt;&lt;</span><span class="p" data-group-id="4289618789-1">&gt;&gt;</span><span class="w">  </span><span class="c1">% The empty bit string, zero length</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4289618789-2">&lt;&lt;</span><span class="n">E1</span><span class="p" data-group-id="4289618789-2">&gt;&gt;</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4289618789-3">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">En</span><span class="p" data-group-id="4289618789-3">&gt;&gt;</span></code></pre><p>Each element <code class="inline">Ei</code> specifies a <em>segment</em> of the bit string. The segments are
│ │ │ │ +ordered from the most significant bit to the least significant bit.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2159523154-1">&lt;&lt;</span><span class="p" data-group-id="2159523154-1">&gt;&gt;</span><span class="w">  </span><span class="c1">% The empty bit string, zero length</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2159523154-2">&lt;&lt;</span><span class="n">E1</span><span class="p" data-group-id="2159523154-2">&gt;&gt;</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2159523154-3">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">En</span><span class="p" data-group-id="2159523154-3">&gt;&gt;</span></code></pre><p>Each element <code class="inline">Ei</code> specifies a <em>segment</em> of the bit string. The segments are
│ │ │ │  ordered left to right from the most significant bit to the least significant bit
│ │ │ │  of the bit string.</p><p>Each segment specification <code class="inline">Ei</code> is a value, whose default type is <code class="inline">integer</code>,
│ │ │ │  followed by an optional <em>size expression</em> and an optional <em>type specifier list</em>.</p><pre><code class="makeup erlang" translate="no"><span class="n">Ei</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Value</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │ │       </span><span class="n">Value</span><span class="p">:</span><span class="n">Size</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │ │       </span><span class="n">Value</span><span class="o">/</span><span class="n">TypeSpecifierList</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │ │       </span><span class="n">Value</span><span class="p">:</span><span class="n">Size</span><span class="o">/</span><span class="n">TypeSpecifierList</span></code></pre><p>When used in a bit string construction, <code class="inline">Value</code> is an expression that is to
│ │ │ │  evaluate to an integer, float, or bit string. If the expression is not a single
│ │ │ │ @@ -703,34 +703,34 @@
│ │ │ │  <a href="expressions.xhtml#guard-expressions">guard expression</a> that evaluates to an
│ │ │ │  integer. All variables in the guard expression must be already bound.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 23, <code class="inline">Size</code> was restricted to be an integer or a variable
│ │ │ │  bound to an integer.</p></section><p>The value of <code class="inline">Size</code> specifies the size of the segment in units (see below). The
│ │ │ │  default value depends on the type (see below):</p><ul><li>For <code class="inline">integer</code> it is 8.</li><li>For <code class="inline">float</code> it is 64.</li><li>For <code class="inline">binary</code> and <code class="inline">bitstring</code> it is the whole binary or bit string.</li></ul><p>In matching, the default value for a binary or bit string segment is only valid
│ │ │ │  for the last element. All other bit string or binary elements in the matching
│ │ │ │  must have a size specification.</p><p><a href="" id="binaries"></a></p><p><strong>Binaries</strong></p><p>A bit string with a length that is a multiple of 8 bits is known as a <em>binary</em>,
│ │ │ │  which is the most common and useful type of bit string.</p><p>A binary has a canonical representation in memory. Here follows a sequence of
│ │ │ │ -bytes where each byte's value is its sequence number:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1796233994-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p" data-group-id="1796233994-1">&gt;&gt;</span></code></pre><p>Bit strings are a later generalization of binaries, so many texts and much
│ │ │ │ -information about binaries apply just as well for bit strings.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="2970137975-1">&lt;&lt;</span><span class="n">A</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2970137975-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2970137975-2">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="2970137975-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +bytes where each byte's value is its sequence number:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4876023498-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p" data-group-id="4876023498-1">&gt;&gt;</span></code></pre><p>Bit strings are a later generalization of binaries, so many texts and much
│ │ │ │ +information about binaries apply just as well for bit strings.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9215308050-1">&lt;&lt;</span><span class="n">A</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9215308050-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9215308050-2">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="9215308050-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">* 1:3: a binary field without size is only allowed at the end of a binary pattern</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="2970137975-3">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">3</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2970137975-3">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2970137975-4">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="2970137975-4">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2970137975-5">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="2970137975-5">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="9215308050-3">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">3</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9215308050-3">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9215308050-4">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="9215308050-4">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9215308050-5">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="9215308050-5">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │  3&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2970137975-6">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="2970137975-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +</span><span class="p" data-group-id="9215308050-6">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="9215308050-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │  4&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2970137975-7">&lt;&lt;</span><span class="s">&quot;de&quot;</span><span class="p" data-group-id="2970137975-7">&gt;&gt;</span></code></pre><p>For the <code class="inline">utf8</code>, <code class="inline">utf16</code>, and <code class="inline">utf32</code> types, <code class="inline">Size</code> must not be given. The size
│ │ │ │ +</span><span class="p" data-group-id="9215308050-7">&lt;&lt;</span><span class="s">&quot;de&quot;</span><span class="p" data-group-id="9215308050-7">&gt;&gt;</span></code></pre><p>For the <code class="inline">utf8</code>, <code class="inline">utf16</code>, and <code class="inline">utf32</code> types, <code class="inline">Size</code> must not be given. The size
│ │ │ │  of the segment is implicitly determined by the type and value itself.</p><p><code class="inline">TypeSpecifierList</code> is a list of type specifiers, in any order, separated by
│ │ │ │  hyphens (-). Default values are used for any omitted type specifiers.</p><ul><li><p><strong><code class="inline">Type</code>= <code class="inline">integer</code> | <code class="inline">float</code> | <code class="inline">binary</code> | <code class="inline">bytes</code> | <code class="inline">bitstring</code> | <code class="inline">bits</code> |
│ │ │ │  <code class="inline">utf8</code> | <code class="inline">utf16</code> | <code class="inline">utf32</code></strong> - The default is <code class="inline">integer</code>. <code class="inline">bytes</code> is a
│ │ │ │  shorthand for <code class="inline">binary</code> and <code class="inline">bits</code> is a shorthand for <code class="inline">bitstring</code>. See below
│ │ │ │  for more information about the <code class="inline">utf</code> types.</p></li><li><p><strong><code class="inline">Signedness</code>= <code class="inline">signed</code> | <code class="inline">unsigned</code></strong> - Only matters for matching and when
│ │ │ │  the type is <code class="inline">integer</code>. The default is <code class="inline">unsigned</code>.</p></li><li><p><strong><code class="inline">Endianness</code>= <code class="inline">big</code> | <code class="inline">little</code> | <code class="inline">native</code></strong> - Specifies byte level (octet
│ │ │ │  level) endianness (byte order). Native-endian means that the endianness is
│ │ │ │  resolved at load time to be either big-endian or little-endian, depending on
│ │ │ │  what is native for the CPU that the Erlang machine is run on. Endianness only
│ │ │ │  matters when the <strong>Type</strong> is either <code class="inline">integer</code>, <code class="inline">utf16</code>, <code class="inline">utf32</code>, or <code class="inline">float</code>. The
│ │ │ │ -default is <code class="inline">big</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8887477952-1">&lt;&lt;</span><span class="mi">16#1234</span><span class="p">:</span><span class="mi">16</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="8887477952-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8887477952-2">&lt;&lt;</span><span class="mi">16#3412</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="8887477952-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8887477952-3">&lt;&lt;</span><span class="mi">16#34</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">16#12</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="8887477952-3">&gt;&gt;</span></code></pre></li><li><p><strong><code class="inline">Unit</code>= <code class="inline">unit:IntegerLiteral</code></strong> - The allowed range is 1 through 256.
│ │ │ │ +default is <code class="inline">big</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6100797552-1">&lt;&lt;</span><span class="mi">16#1234</span><span class="p">:</span><span class="mi">16</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="6100797552-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6100797552-2">&lt;&lt;</span><span class="mi">16#3412</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="6100797552-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6100797552-3">&lt;&lt;</span><span class="mi">16#34</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">16#12</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="6100797552-3">&gt;&gt;</span></code></pre></li><li><p><strong><code class="inline">Unit</code>= <code class="inline">unit:IntegerLiteral</code></strong> - The allowed range is 1 through 256.
│ │ │ │  Defaults to 1 for <code class="inline">integer</code>, <code class="inline">float</code>, and <code class="inline">bitstring</code>, and to 8 for <code class="inline">binary</code>.
│ │ │ │  For types <code class="inline">bitstring</code>, <code class="inline">bits</code>, and <code class="inline">bytes</code>, it is not allowed to specify a
│ │ │ │  unit value different from the default value. No unit specifier must be given
│ │ │ │  for the types <code class="inline">utf8</code>, <code class="inline">utf16</code>, and <code class="inline">utf32</code>.</p></li></ul><h3 id="integer-segments" class="section-heading">
│ │ │ │    <a href="#integer-segments" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │ @@ -755,41 +755,41 @@
│ │ │ │    </a>
│ │ │ │    <span class="text">Binary segments</span>
│ │ │ │  </h3>
│ │ │ │  <p>In this section, the phrase &quot;binary segment&quot; refers to any one of the segment
│ │ │ │  types <code class="inline">binary</code>, <code class="inline">bitstring</code>, <code class="inline">bytes</code>, and <code class="inline">bits</code>.</p><p>See also the paragraphs about <a href="expressions.xhtml#binaries">Binaries</a>.</p><p>When constructing binaries and no size is specified for a binary segment, the
│ │ │ │  entire binary value is interpolated into the binary being constructed. However,
│ │ │ │  the size in bits of the binary being interpolated must be evenly divisible by
│ │ │ │ -the unit value for the segment; otherwise an exception is raised.</p><p>For example, the following examples all succeed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3323271315-1">&lt;&lt;</span><span class="p" data-group-id="3323271315-2">(</span><span class="p" data-group-id="3323271315-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3323271315-3">&gt;&gt;</span><span class="p" data-group-id="3323271315-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3323271315-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3323271315-4">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3323271315-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="3323271315-5">&lt;&lt;</span><span class="p" data-group-id="3323271315-6">(</span><span class="p" data-group-id="3323271315-7">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3323271315-7">&gt;&gt;</span><span class="p" data-group-id="3323271315-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3323271315-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3323271315-8">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3323271315-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="p" data-group-id="3323271315-9">&lt;&lt;</span><span class="p" data-group-id="3323271315-10">(</span><span class="p" data-group-id="3323271315-11">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3323271315-11">&gt;&gt;</span><span class="p" data-group-id="3323271315-10">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3323271315-9">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3323271315-12">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3323271315-12">&gt;&gt;</span></code></pre><p>The first two examples have a unit value of 1 for the segment, while the third
│ │ │ │ +the unit value for the segment; otherwise an exception is raised.</p><p>For example, the following examples all succeed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0083673504-1">&lt;&lt;</span><span class="p" data-group-id="0083673504-2">(</span><span class="p" data-group-id="0083673504-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0083673504-3">&gt;&gt;</span><span class="p" data-group-id="0083673504-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="0083673504-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0083673504-4">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0083673504-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="0083673504-5">&lt;&lt;</span><span class="p" data-group-id="0083673504-6">(</span><span class="p" data-group-id="0083673504-7">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0083673504-7">&gt;&gt;</span><span class="p" data-group-id="0083673504-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="0083673504-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0083673504-8">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0083673504-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +3&gt; </span><span class="p" data-group-id="0083673504-9">&lt;&lt;</span><span class="p" data-group-id="0083673504-10">(</span><span class="p" data-group-id="0083673504-11">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0083673504-11">&gt;&gt;</span><span class="p" data-group-id="0083673504-10">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0083673504-9">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0083673504-12">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0083673504-12">&gt;&gt;</span></code></pre><p>The first two examples have a unit value of 1 for the segment, while the third
│ │ │ │  segment has a unit value of 8.</p><p>Attempting to interpolate a bit string of size 1 into a binary segment with unit
│ │ │ │ -8 (the default unit for <code class="inline">binary</code>) fails as shown in this example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0082034841-1">&lt;&lt;</span><span class="p" data-group-id="0082034841-2">(</span><span class="p" data-group-id="0082034841-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="0082034841-3">&gt;&gt;</span><span class="p" data-group-id="0082034841-2">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0082034841-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="gt">** exception error: bad argument</span></code></pre><p>For the construction to succeed, the unit value of the segment must be 1:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="4275101931-1">&lt;&lt;</span><span class="p" data-group-id="4275101931-2">(</span><span class="p" data-group-id="4275101931-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="4275101931-3">&gt;&gt;</span><span class="p" data-group-id="4275101931-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="4275101931-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4275101931-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="4275101931-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="p" data-group-id="4275101931-5">&lt;&lt;</span><span class="p" data-group-id="4275101931-6">(</span><span class="p" data-group-id="4275101931-7">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="4275101931-7">&gt;&gt;</span><span class="p" data-group-id="4275101931-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="4275101931-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4275101931-8">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="4275101931-8">&gt;&gt;</span></code></pre><p>Similarly, when matching a binary segment with no size specified, the match
│ │ │ │ +8 (the default unit for <code class="inline">binary</code>) fails as shown in this example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3396243368-1">&lt;&lt;</span><span class="p" data-group-id="3396243368-2">(</span><span class="p" data-group-id="3396243368-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3396243368-3">&gt;&gt;</span><span class="p" data-group-id="3396243368-2">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3396243368-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="gt">** exception error: bad argument</span></code></pre><p>For the construction to succeed, the unit value of the segment must be 1:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="3571277663-1">&lt;&lt;</span><span class="p" data-group-id="3571277663-2">(</span><span class="p" data-group-id="3571277663-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3571277663-3">&gt;&gt;</span><span class="p" data-group-id="3571277663-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3571277663-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3571277663-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3571277663-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +3&gt; </span><span class="p" data-group-id="3571277663-5">&lt;&lt;</span><span class="p" data-group-id="3571277663-6">(</span><span class="p" data-group-id="3571277663-7">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3571277663-7">&gt;&gt;</span><span class="p" data-group-id="3571277663-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3571277663-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3571277663-8">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3571277663-8">&gt;&gt;</span></code></pre><p>Similarly, when matching a binary segment with no size specified, the match
│ │ │ │  succeeds if and only if the size in bits of the rest of the binary is evenly
│ │ │ │ -divisible by the unit value:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9389722270-1">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9389722270-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9389722270-2">&lt;&lt;</span><span class="s">&quot;&quot;</span><span class="p" data-group-id="9389722270-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9389722270-3">&lt;&lt;</span><span class="p" data-group-id="9389722270-3">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="9389722270-4">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9389722270-4">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9389722270-5">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="9389722270-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +divisible by the unit value:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0558810245-1">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0558810245-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0558810245-2">&lt;&lt;</span><span class="s">&quot;&quot;</span><span class="p" data-group-id="0558810245-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0558810245-3">&lt;&lt;</span><span class="p" data-group-id="0558810245-3">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="0558810245-4">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0558810245-4">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0558810245-5">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="0558810245-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no match of right hand side value &lt;&lt;&quot;a&quot;&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="p" data-group-id="9389722270-6">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9389722270-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9389722270-7">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="9389722270-7">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9389722270-8">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="9389722270-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="p" data-group-id="9389722270-9">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9389722270-9">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9389722270-10">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="9389722270-10">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="p" data-group-id="0558810245-6">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0558810245-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0558810245-7">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="0558810245-7">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0558810245-8">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="0558810245-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +4&gt; </span><span class="p" data-group-id="0558810245-9">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0558810245-9">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0558810245-10">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0558810245-10">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: no match of right hand side value &lt;&lt;&quot;abc&quot;&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="p" data-group-id="9389722270-11">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9389722270-11">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9389722270-12">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="9389722270-12">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9389722270-13">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="9389722270-13">&gt;&gt;</span></code></pre><p>When a size is explicitly specified for a binary segment, the segment size in
│ │ │ │ +5&gt; </span><span class="p" data-group-id="0558810245-11">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0558810245-11">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0558810245-12">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="0558810245-12">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0558810245-13">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="0558810245-13">&gt;&gt;</span></code></pre><p>When a size is explicitly specified for a binary segment, the segment size in
│ │ │ │  bits is the value of <code class="inline">Size</code> multiplied by the default or explicit unit value.</p><p>When constructing binaries, the size of the binary being interpolated into the
│ │ │ │ -constructed binary must be at least as large as the size of the binary segment.</p><p><strong>Examples:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="1819053403-1">&lt;&lt;</span><span class="p" data-group-id="1819053403-2">(</span><span class="p" data-group-id="1819053403-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="1819053403-3">&gt;&gt;</span><span class="p" data-group-id="1819053403-2">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="1819053403-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1819053403-4">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="1819053403-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="1819053403-5">&lt;&lt;</span><span class="p" data-group-id="1819053403-6">(</span><span class="p" data-group-id="1819053403-7">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="1819053403-7">&gt;&gt;</span><span class="p" data-group-id="1819053403-6">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="1819053403-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +constructed binary must be at least as large as the size of the binary segment.</p><p><strong>Examples:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7224988620-1">&lt;&lt;</span><span class="p" data-group-id="7224988620-2">(</span><span class="p" data-group-id="7224988620-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7224988620-3">&gt;&gt;</span><span class="p" data-group-id="7224988620-2">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7224988620-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7224988620-4">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="7224988620-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="7224988620-5">&lt;&lt;</span><span class="p" data-group-id="7224988620-6">(</span><span class="p" data-group-id="7224988620-7">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="7224988620-7">&gt;&gt;</span><span class="p" data-group-id="7224988620-6">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7224988620-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: construction of binary failed
│ │ │ │          *** segment 1 of type &#39;binary&#39;: the value &lt;&lt;&quot;a&quot;&gt;&gt; is shorter than the size of the segment</span></code></pre><h3 id="unicode-segments" class="section-heading">
│ │ │ │    <a href="#unicode-segments" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Unicode segments</span>
│ │ │ │  </h3>
│ │ │ │ @@ -805,78 +805,78 @@
│ │ │ │  range <code class="inline">0</code> through <code class="inline">16#D7FF</code> or <code class="inline">16#E000</code> through <code class="inline">16#10FFFF</code>. The match fails if the
│ │ │ │  returned value falls outside those ranges.</p><p>A segment of type <code class="inline">utf8</code> matches 1-4 bytes in the bit string, if the bit string
│ │ │ │  at the match position contains a valid UTF-8 sequence. (See RFC-3629 or the
│ │ │ │  Unicode standard.)</p><p>A segment of type <code class="inline">utf16</code> can match 2 or 4 bytes in the bit string. The match
│ │ │ │  fails if the bit string at the match position does not contain a legal UTF-16
│ │ │ │  encoding of a Unicode code point. (See RFC-2781 or the Unicode standard.)</p><p>A segment of type <code class="inline">utf32</code> can match 4 bytes in the bit string in the same way as
│ │ │ │  an <code class="inline">integer</code> segment matches 32 bits. The match fails if the resulting integer
│ │ │ │ -is outside the legal ranges previously mentioned.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0548875174-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0548875174-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="0548875174-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-4">&lt;&lt;</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="0548875174-4">&gt;&gt;</span><span class="w">
│ │ │ │ +is outside the legal ranges previously mentioned.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="9591627239-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="9591627239-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="9591627239-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-4">&lt;&lt;</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="9591627239-4">&gt;&gt;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0548875174-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-6">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0548875174-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="p" data-group-id="0548875174-7">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0548875174-7">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-8">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0548875174-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-9">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0548875174-9">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9591627239-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-6">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="9591627239-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +4&gt; </span><span class="p" data-group-id="9591627239-7">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9591627239-7">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-8">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9591627239-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-9">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="9591627239-9">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │  5&gt; </span><span class="n">C</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="p" data-group-id="0548875174-10">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="n">E</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="0548875174-10">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-11">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0548875174-11">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-12">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0548875174-12">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +6&gt; </span><span class="p" data-group-id="9591627239-10">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="n">E</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="9591627239-10">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-11">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9591627239-11">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-12">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="9591627239-12">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │  7&gt; </span><span class="n">D</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">273</span><span class="gp unselectable">
│ │ │ │  8&gt; </span><span class="n">F</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │ │ -9&gt; </span><span class="p" data-group-id="0548875174-13">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">H</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0548875174-13">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-14">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="0548875174-14">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-15">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0548875174-15">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +9&gt; </span><span class="p" data-group-id="9591627239-13">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">H</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9591627239-13">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-14">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9591627239-14">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-15">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="9591627239-15">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │  10&gt; </span><span class="n">H</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-16">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="0548875174-16">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -11&gt; </span><span class="p" data-group-id="0548875174-17">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">J</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="0548875174-17">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-18">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="0548875174-18">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-19">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="0548875174-19">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-16">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="9591627239-16">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +11&gt; </span><span class="p" data-group-id="9591627239-17">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">J</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="9591627239-17">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-18">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="9591627239-18">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-19">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="9591627239-19">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │  12&gt; </span><span class="n">J</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-20">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="0548875174-20">&gt;&gt;</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-20">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="9591627239-20">&gt;&gt;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="mi">13</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="0548875174-21">&lt;&lt;</span><span class="mi">1024</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="0548875174-21">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-22">&lt;&lt;</span><span class="mi">208</span><span class="p">,</span><span class="mi">128</span><span class="p" data-group-id="0548875174-22">&gt;&gt;</span><span class="w">
│ │ │ │ +</span><span class="mi">13</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="9591627239-21">&lt;&lt;</span><span class="mi">1024</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="9591627239-21">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-22">&lt;&lt;</span><span class="mi">208</span><span class="p">,</span><span class="mi">128</span><span class="p" data-group-id="9591627239-22">&gt;&gt;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="mi">14</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="0548875174-23">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">:</span><span class="mi">7</span><span class="p" data-group-id="0548875174-23">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-24">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="0548875174-24">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -15&gt; </span><span class="p" data-group-id="0548875174-25">&lt;&lt;</span><span class="mi">16#123</span><span class="p">:</span><span class="mi">12</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="0548875174-25">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-26">&lt;&lt;</span><span class="mi">16#231</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="0548875174-26">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0548875174-27">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="0548875174-27">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0548875174-28">&lt;&lt;</span><span class="mi">35</span><span class="p">,</span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="0548875174-28">&gt;&gt;</span></code></pre><p>Notice that bit string patterns cannot be nested.</p><p>Notice also that &quot;<code class="inline">B=&lt;&lt;1&gt;&gt;</code>&quot; is interpreted as &quot;<code class="inline">B =&lt; &lt;1&gt;&gt;</code>&quot; which is a syntax
│ │ │ │ +</span><span class="mi">14</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="9591627239-23">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">:</span><span class="mi">7</span><span class="p" data-group-id="9591627239-23">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-24">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="9591627239-24">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +15&gt; </span><span class="p" data-group-id="9591627239-25">&lt;&lt;</span><span class="mi">16#123</span><span class="p">:</span><span class="mi">12</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="9591627239-25">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-26">&lt;&lt;</span><span class="mi">16#231</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="9591627239-26">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591627239-27">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="9591627239-27">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9591627239-28">&lt;&lt;</span><span class="mi">35</span><span class="p">,</span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="9591627239-28">&gt;&gt;</span></code></pre><p>Notice that bit string patterns cannot be nested.</p><p>Notice also that &quot;<code class="inline">B=&lt;&lt;1&gt;&gt;</code>&quot; is interpreted as &quot;<code class="inline">B =&lt; &lt;1&gt;&gt;</code>&quot; which is a syntax
│ │ │ │  error. The correct way is to write a space after <code class="inline">=</code>: &quot;<code class="inline">B = &lt;&lt;1&gt;&gt;</code>.</p><p>More examples are provided in <a href="../../../lib/../system/doc/html/bit_syntax.xhtml">Programming Examples</a>.</p><h2 id="fun-expressions" class="section-heading">
│ │ │ │    <a href="#fun-expressions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Fun Expressions</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">fun</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1470741847-1">[</span><span class="n">Name</span><span class="p" data-group-id="1470741847-1">]</span><span class="p" data-group-id="1470741847-2">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="1470741847-2">)</span><span class="w"> </span><span class="p" data-group-id="1470741847-3">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="1470741847-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6385770687-1">[</span><span class="n">Name</span><span class="p" data-group-id="6385770687-1">]</span><span class="p" data-group-id="6385770687-2">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="6385770687-2">)</span><span class="w"> </span><span class="p" data-group-id="6385770687-3">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="6385770687-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1470741847-4">[</span><span class="n">Name</span><span class="p" data-group-id="1470741847-4">]</span><span class="p" data-group-id="1470741847-5">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="1470741847-5">)</span><span class="w"> </span><span class="p" data-group-id="1470741847-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="1470741847-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6385770687-4">[</span><span class="n">Name</span><span class="p" data-group-id="6385770687-4">]</span><span class="p" data-group-id="6385770687-5">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="6385770687-5">)</span><span class="w"> </span><span class="p" data-group-id="6385770687-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="6385770687-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                </span><span class="n">BodyK</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>A fun expression begins with the keyword <code class="inline">fun</code> and ends with the keyword <code class="inline">end</code>.
│ │ │ │  Between them is to be a function declaration, similar to a
│ │ │ │  <a href="ref_man_functions.xhtml#function-declaration-syntax">regular function declaration</a>,
│ │ │ │  except that the function name is optional and is to be a variable, if any.</p><p>Variables in a fun head shadow the function name and both shadow variables in
│ │ │ │  the function clause surrounding the fun expression. Variables bound in a fun
│ │ │ │ -body are local to the fun body.</p><p>The return value of the expression is the resulting fun.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2790403643-1">(</span><span class="n">X</span><span class="p" data-group-id="2790403643-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +body are local to the fun body.</p><p>The return value of the expression is the resulting fun.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3768713207-1">(</span><span class="n">X</span><span class="p" data-group-id="3768713207-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="2790403643-2">(</span><span class="mi">2</span><span class="p" data-group-id="2790403643-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="3768713207-2">(</span><span class="mi">2</span><span class="p" data-group-id="3768713207-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="n">Fun2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2790403643-3">(</span><span class="n">X</span><span class="p" data-group-id="2790403643-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="o">&gt;=</span><span class="mi">5</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">gt</span><span class="p">;</span><span class="w"> </span><span class="p" data-group-id="2790403643-4">(</span><span class="n">X</span><span class="p" data-group-id="2790403643-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">lt</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="n">Fun2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3768713207-3">(</span><span class="n">X</span><span class="p" data-group-id="3768713207-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="o">&gt;=</span><span class="mi">5</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">gt</span><span class="p">;</span><span class="w"> </span><span class="p" data-group-id="3768713207-4">(</span><span class="n">X</span><span class="p" data-group-id="3768713207-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">lt</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="n">Fun2</span><span class="p" data-group-id="2790403643-5">(</span><span class="mi">7</span><span class="p" data-group-id="2790403643-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="n">Fun2</span><span class="p" data-group-id="3768713207-5">(</span><span class="mi">7</span><span class="p" data-group-id="3768713207-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">gt</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="n">Fun3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="2790403643-6">(</span><span class="mi">1</span><span class="p" data-group-id="2790403643-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="2790403643-7">(</span><span class="n">X</span><span class="p" data-group-id="2790403643-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="2790403643-8">(</span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="2790403643-8">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="n">Fun3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="3768713207-6">(</span><span class="mi">1</span><span class="p" data-group-id="3768713207-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="3768713207-7">(</span><span class="n">X</span><span class="p" data-group-id="3768713207-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="3768713207-8">(</span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3768713207-8">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="n">Fun3</span><span class="p" data-group-id="2790403643-9">(</span><span class="mi">4</span><span class="p" data-group-id="2790403643-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="n">Fun3</span><span class="p" data-group-id="3768713207-9">(</span><span class="mi">4</span><span class="p" data-group-id="3768713207-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">24</span></code></pre><p>The following fun expressions are also allowed:</p><pre><code class="makeup erlang" translate="no"><span class="k">fun</span><span class="w"> </span><span class="n">Name</span><span class="o">/</span><span class="n">Arity</span><span class="w">
│ │ │ │  </span><span class="k">fun</span><span class="w"> </span><span class="n">Module</span><span class="p">:</span><span class="n">Name</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>In <code class="inline">Name/Arity</code>, <code class="inline">Name</code> is an atom and <code class="inline">Arity</code> is an integer. <code class="inline">Name/Arity</code> must
│ │ │ │ -specify an existing local function. The expression is syntactic sugar for:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="5012321946-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="5012321946-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5012321946-2">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="5012321946-2">)</span><span class="w"> </span><span class="k">end</span></code></pre><p>In <code class="inline">Module:Name/Arity</code>, <code class="inline">Module</code>, and <code class="inline">Name</code> are atoms and <code class="inline">Arity</code> is an
│ │ │ │ +specify an existing local function. The expression is syntactic sugar for:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="4265487529-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="4265487529-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4265487529-2">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="4265487529-2">)</span><span class="w"> </span><span class="k">end</span></code></pre><p>In <code class="inline">Module:Name/Arity</code>, <code class="inline">Module</code>, and <code class="inline">Name</code> are atoms and <code class="inline">Arity</code> is an
│ │ │ │  integer. <code class="inline">Module</code>, <code class="inline">Name</code>, and <code class="inline">Arity</code> can also be variables. A fun defined in
│ │ │ │  this way refers to the function <code class="inline">Name</code> with arity <code class="inline">Arity</code> in the <em>latest</em>
│ │ │ │  version of module <code class="inline">Module</code>. A fun defined in this way is not dependent on the
│ │ │ │  code for the module in which it is defined.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP R15, <code class="inline">Module</code>, <code class="inline">Name</code>, and <code class="inline">Arity</code> were not allowed to be
│ │ │ │  variables.</p></section><p>More examples are provided in <a href="../../../lib/../system/doc/html/funs.xhtml">Programming Examples</a>.</p><h2 id="catch-and-throw" class="section-heading">
│ │ │ │    <a href="#catch-and-throw" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │ @@ -886,35 +886,35 @@
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">catch</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>Returns the value of <code class="inline">Expr</code> unless an exception is raised during the evaluation. In
│ │ │ │  that case, the exception is caught. The return value depends on the class of the
│ │ │ │  exception:</p><ul><li><p><strong><code class="inline">error</code></strong> (a run-time error or the code called <a href="../../../lib/../erts/doc/html/erlang.html#error/1"><code class="inline">error(Term)</code></a>) -
│ │ │ │  <code class="inline">{'EXIT',{Reason,Stack}}</code> is returned.</p></li><li><p><strong><code class="inline">exit</code></strong> (the code called <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit(Term)</code></a>) - <code class="inline">{'EXIT',Term}</code> is returned.</p></li><li><p><strong><code class="inline">throw</code></strong> (the code called <a href="../../../lib/../erts/doc/html/erlang.html#throw/1"><code class="inline">throw(Term)</code></a>): <code class="inline">Term</code> is returned.</p></li></ul><p><code class="inline">Reason</code> depends on the type of error that occurred, and <code class="inline">Stack</code> is the stack of
│ │ │ │  recent function calls, see <a href="errors.xhtml#exit_reasons">Exit Reasons</a>.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="k">catch</span><span class="w"> </span><span class="mi">1</span><span class="o">+</span><span class="mi">2</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │  2&gt; </span><span class="k">catch</span><span class="w"> </span><span class="mi">1</span><span class="o">+</span><span class="ss">a</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6413542518-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="6413542518-2">{</span><span class="ss">badarith</span><span class="p">,</span><span class="p" data-group-id="6413542518-3">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6413542518-3">]</span><span class="p" data-group-id="6413542518-2">}</span><span class="p" data-group-id="6413542518-1">}</span></code></pre><p>The BIF <a href="../../../lib/../erts/doc/html/erlang.html#throw/1"><code class="inline">throw(Any)</code></a> can be used for non-local return from a
│ │ │ │ -function. It must be evaluated within a <code class="inline">catch</code>, which returns the value <code class="inline">Any</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="6317537786-1">(</span><span class="ss">hello</span><span class="p" data-group-id="6317537786-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8947711399-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="8947711399-2">{</span><span class="ss">badarith</span><span class="p">,</span><span class="p" data-group-id="8947711399-3">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="8947711399-3">]</span><span class="p" data-group-id="8947711399-2">}</span><span class="p" data-group-id="8947711399-1">}</span></code></pre><p>The BIF <a href="../../../lib/../erts/doc/html/erlang.html#throw/1"><code class="inline">throw(Any)</code></a> can be used for non-local return from a
│ │ │ │ +function. It must be evaluated within a <code class="inline">catch</code>, which returns the value <code class="inline">Any</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="0275942719-1">(</span><span class="ss">hello</span><span class="p" data-group-id="0275942719-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span></code></pre><p>If <a href="../../../lib/../erts/doc/html/erlang.html#throw/1"><code class="inline">throw/1</code></a> is not evaluated within a catch, a <code class="inline">nocatch</code> run-time
│ │ │ │  error occurs.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 24, the <code class="inline">catch</code> operator had the lowest precedence, making
│ │ │ │ -it necessary to add parentheses when combining it with the <code class="inline">match</code> operator:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4077312316-1">(</span><span class="k">catch</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="4077312316-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +it necessary to add parentheses when combining it with the <code class="inline">match</code> operator:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1387140970-1">(</span><span class="k">catch</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="1387140970-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │ │  2&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span></code></pre><p>Starting from Erlang/OTP 24, the parentheses can be omitted:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">catch</span><span class="w"> </span><span class="mi">42</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │ │  2&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">42</span></code></pre></section><h2 id="try" class="section-heading">
│ │ │ │    <a href="#try" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Try</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w">
│ │ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ │ -    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="4149295679-1">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="4149295679-1">]</span><span class="w"> </span><span class="p" data-group-id="4149295679-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="4149295679-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="6436482759-1">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="6436482759-1">]</span><span class="w"> </span><span class="p" data-group-id="6436482759-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="6436482759-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="4149295679-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="4149295679-3">]</span><span class="w"> </span><span class="p" data-group-id="4149295679-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="4149295679-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="6436482759-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="6436482759-3">]</span><span class="w"> </span><span class="p" data-group-id="6436482759-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="6436482759-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>This is an enhancement of <a href="expressions.xhtml#catch-and-throw">catch</a>. It gives the
│ │ │ │  possibility to:</p><ul><li>Distinguish between different exception classes.</li><li>Choose to handle only the desired ones.</li><li>Passing the others on to an enclosing <code class="inline">try</code> or <code class="inline">catch</code>, or to default error
│ │ │ │  handling.</li></ul><p>Notice that although the keyword <code class="inline">catch</code> is used in the <code class="inline">try</code> expression, there
│ │ │ │  is not a <code class="inline">catch</code> expression within the <code class="inline">try</code> expression.</p><p>It returns the value of <code class="inline">Exprs</code> (a sequence of expressions <code class="inline">Expr1, ..., ExprN</code>)
│ │ │ │  unless an exception occurs during the evaluation. In that case the exception is
│ │ │ │  caught and the patterns <code class="inline">ExceptionPattern</code> with the right exception class
│ │ │ │ @@ -924,47 +924,47 @@
│ │ │ │  stack trace is bound to the variable when the corresponding <code class="inline">ExceptionPattern</code>
│ │ │ │  matches.</p><p>If an exception occurs during evaluation of <code class="inline">Exprs</code> but there is no matching
│ │ │ │  <code class="inline">ExceptionPattern</code> of the right <code class="inline">Class</code> with a true guard sequence, the
│ │ │ │  exception is passed on as if <code class="inline">Exprs</code> had not been enclosed in a <code class="inline">try</code>
│ │ │ │  expression.</p><p>If an exception occurs during evaluation of <code class="inline">ExceptionBody</code>, it is not caught.</p><p>It is allowed to omit <code class="inline">Class</code> and <code class="inline">Stacktrace</code>. An omitted <code class="inline">Class</code> is shorthand
│ │ │ │  for <code class="inline">throw</code>:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w">
│ │ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ │ -    </span><span class="n">ExceptionPattern1</span><span class="w"> </span><span class="p" data-group-id="0653223793-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="0653223793-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">ExceptionPattern1</span><span class="w"> </span><span class="p" data-group-id="5464134428-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="5464134428-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">ExceptionPatternN</span><span class="w"> </span><span class="p" data-group-id="0653223793-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="0653223793-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">ExceptionPatternN</span><span class="w"> </span><span class="p" data-group-id="5464134428-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="5464134428-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>The <code class="inline">try</code> expression can have an <code class="inline">of</code> section:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="2751870540-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="2751870540-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="9195824565-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="9195824565-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="2751870540-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="2751870540-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="9195824565-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="9195824565-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ │ -    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="2751870540-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="2751870540-3">]</span><span class="w"> </span><span class="p" data-group-id="2751870540-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="2751870540-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="9195824565-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="9195824565-3">]</span><span class="w"> </span><span class="p" data-group-id="9195824565-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="9195824565-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="2751870540-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="2751870540-5">]</span><span class="w"> </span><span class="p" data-group-id="2751870540-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="2751870540-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="9195824565-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="9195824565-5">]</span><span class="w"> </span><span class="p" data-group-id="9195824565-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="9195824565-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>If the evaluation of <code class="inline">Exprs</code> succeeds without an exception, the patterns
│ │ │ │  <code class="inline">Pattern</code> are sequentially matched against the result in the same way as for a
│ │ │ │  <a href="expressions.xhtml#case">case</a> expression, except that if the matching fails, a
│ │ │ │  <code class="inline">try_clause</code> run-time error occurs instead of a <code class="inline">case_clause</code>.</p><p>Only exceptions occurring during the evaluation of <code class="inline">Exprs</code> can be caught by the
│ │ │ │  <code class="inline">catch</code> section. Exceptions occurring in a <code class="inline">Body</code> or due to a failed match are
│ │ │ │  not caught.</p><p>The <code class="inline">try</code> expression can also be augmented with an <code class="inline">after</code> section, intended to
│ │ │ │  be used for cleanup with side effects:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="3186989750-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="3186989750-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="5907010774-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="5907010774-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="3186989750-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="3186989750-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="5907010774-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="5907010774-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ │ -    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="3186989750-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="3186989750-3">]</span><span class="w"> </span><span class="p" data-group-id="3186989750-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="3186989750-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="5907010774-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="5907010774-3">]</span><span class="w"> </span><span class="p" data-group-id="5907010774-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="5907010774-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="3186989750-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="3186989750-5">]</span><span class="w"> </span><span class="p" data-group-id="3186989750-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="3186989750-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="5907010774-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="5907010774-5">]</span><span class="w"> </span><span class="p" data-group-id="5907010774-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="5907010774-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │ │  </span><span class="k">after</span><span class="w">
│ │ │ │      </span><span class="n">AfterBody</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p><code class="inline">AfterBody</code> is evaluated after either <code class="inline">Body</code> or <code class="inline">ExceptionBody</code>, no matter which
│ │ │ │  one. The evaluated value of <code class="inline">AfterBody</code> is lost; the return value of the <code class="inline">try</code>
│ │ │ │  expression is the same with an <code class="inline">after</code> section as without.</p><p>Even if an exception occurs during evaluation of <code class="inline">Body</code> or <code class="inline">ExceptionBody</code>,
│ │ │ │  <code class="inline">AfterBody</code> is evaluated. In this case the exception is passed on after
│ │ │ │ @@ -987,40 +987,40 @@
│ │ │ │          </span><span class="n">ExpressionBody</span><span class="w">
│ │ │ │  </span><span class="k">after</span><span class="w">
│ │ │ │      </span><span class="n">AfterBody</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="n">AfterBody</span><span class="w"> </span><span class="k">end</span></code></pre><p>Next is an example of using <code class="inline">after</code>. This closes the file, even in the event of
│ │ │ │  exceptions in <a href="../../../lib/kernel/doc/html/file.html#read/2"><code class="inline">file:read/2</code></a> or in <a href="../../../lib/../erts/doc/html/erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>. The
│ │ │ │ -exceptions are the same as without the <code class="inline">try</code>...<code class="inline">after</code>...<code class="inline">end</code> expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">termize_file</span><span class="p" data-group-id="8190327294-1">(</span><span class="n">Name</span><span class="p" data-group-id="8190327294-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8190327294-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="8190327294-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="8190327294-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8190327294-4">[</span><span class="ss">read</span><span class="p">,</span><span class="ss">binary</span><span class="p" data-group-id="8190327294-4">]</span><span class="p" data-group-id="8190327294-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +exceptions are the same as without the <code class="inline">try</code>...<code class="inline">after</code>...<code class="inline">end</code> expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">termize_file</span><span class="p" data-group-id="8889031487-1">(</span><span class="n">Name</span><span class="p" data-group-id="8889031487-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8889031487-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="8889031487-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="8889031487-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8889031487-4">[</span><span class="ss">read</span><span class="p">,</span><span class="ss">binary</span><span class="p" data-group-id="8889031487-4">]</span><span class="p" data-group-id="8889031487-3">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">try</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="8190327294-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">Bin</span><span class="p" data-group-id="8190327294-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="8190327294-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1024</span><span class="o">*</span><span class="mi">1024</span><span class="p" data-group-id="8190327294-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="nf">binary_to_term</span><span class="p" data-group-id="8190327294-7">(</span><span class="n">Bin</span><span class="p" data-group-id="8190327294-7">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8889031487-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">Bin</span><span class="p" data-group-id="8889031487-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="8889031487-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1024</span><span class="o">*</span><span class="mi">1024</span><span class="p" data-group-id="8889031487-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="nf">binary_to_term</span><span class="p" data-group-id="8889031487-7">(</span><span class="n">Bin</span><span class="p" data-group-id="8889031487-7">)</span><span class="w">
│ │ │ │      </span><span class="k">after</span><span class="w">
│ │ │ │ -        </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="8190327294-8">(</span><span class="n">F</span><span class="p" data-group-id="8190327294-8">)</span><span class="w">
│ │ │ │ +        </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="8889031487-8">(</span><span class="n">F</span><span class="p" data-group-id="8889031487-8">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Next is an example of using <code class="inline">try</code> to emulate <code class="inline">catch Expr</code>:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Expr</span><span class="w">
│ │ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ │      </span><span class="nc">throw</span><span class="p">:</span><span class="n">Term</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Term</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="nc">exit</span><span class="p">:</span><span class="n">Reason</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1991688229-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="1991688229-1">}</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="nc">error</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stk</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1991688229-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="1991688229-3">{</span><span class="n">Reason</span><span class="p">,</span><span class="n">Stk</span><span class="p" data-group-id="1991688229-3">}</span><span class="p" data-group-id="1991688229-2">}</span><span class="w">
│ │ │ │ +    </span><span class="nc">exit</span><span class="p">:</span><span class="n">Reason</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0131642228-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="0131642228-1">}</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="nc">error</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stk</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0131642228-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="0131642228-3">{</span><span class="n">Reason</span><span class="p">,</span><span class="n">Stk</span><span class="p" data-group-id="0131642228-3">}</span><span class="p" data-group-id="0131642228-2">}</span><span class="w">
│ │ │ │  </span><span class="k">end</span></code></pre><p>Variables bound in the various parts of these expressions have different scopes.
│ │ │ │  Variables bound just after the <code class="inline">try</code> keyword are:</p><ul><li>bound in the <code class="inline">of</code> section</li><li>unsafe in both the <code class="inline">catch</code> and <code class="inline">after</code> sections, as well as after the whole
│ │ │ │  construct</li></ul><p>Variables bound in <code class="inline">of</code> section are:</p><ul><li>unbound in the <code class="inline">catch</code> section</li><li>unsafe in both the <code class="inline">after</code> section, as well as after the whole construct</li></ul><p>Variables bound in the <code class="inline">catch</code> section are unsafe in the <code class="inline">after</code> section, as
│ │ │ │  well as after the whole construct.</p><p>Variables bound in the <code class="inline">after</code> section are unsafe after the whole construct.</p><h2 id="parenthesized-expressions" class="section-heading">
│ │ │ │    <a href="#parenthesized-expressions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Parenthesized Expressions</span>
│ │ │ │  </h2>
│ │ │ │ -<pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1182421987-1">(</span><span class="n">Expr</span><span class="p" data-group-id="1182421987-1">)</span></code></pre><p>Parenthesized expressions are useful to override
│ │ │ │ +<pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6520953772-1">(</span><span class="n">Expr</span><span class="p" data-group-id="6520953772-1">)</span></code></pre><p>Parenthesized expressions are useful to override
│ │ │ │  <a href="expressions.xhtml#prec">operator precedences</a>, for example, in arithmetic
│ │ │ │  expressions:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">7</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="2146792224-1">(</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2146792224-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="5479480037-1">(</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="5479480037-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">9</span></code></pre><h2 id="block-expressions" class="section-heading">
│ │ │ │    <a href="#block-expressions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Block Expressions</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">begin</span><span class="w">
│ │ │ │ @@ -1032,71 +1032,71 @@
│ │ │ │    <a href="#comprehensions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Comprehensions</span>
│ │ │ │  </h2>
│ │ │ │  <p>Comprehensions provide a succinct notation for iterating over one or more terms
│ │ │ │  and constructing a new term. Comprehensions come in three different flavors,
│ │ │ │ -depending on the type of term they build.</p><p>List comprehensions construct lists. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9221303468-1">[</span><span class="n">Expr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="9221303468-1">]</span></code></pre><p>Here, <code class="inline">Expr</code> is an arbitrary expression, and each <code class="inline">Qualifier</code> is either a
│ │ │ │ +depending on the type of term they build.</p><p>List comprehensions construct lists. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0452354305-1">[</span><span class="n">Expr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="0452354305-1">]</span></code></pre><p>Here, <code class="inline">Expr</code> is an arbitrary expression, and each <code class="inline">Qualifier</code> is either a
│ │ │ │  <strong>generator</strong> or a <strong>filter</strong>.</p><p>Bit string comprehensions construct bit strings or binaries. They have the
│ │ │ │ -following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8087533885-1">&lt;&lt;</span><span class="w"> </span><span class="n">BitStringExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="w"> </span><span class="p" data-group-id="8087533885-1">&gt;&gt;</span></code></pre><p><code class="inline">BitStringExpr</code> is an expression that evaluates to a bit string. If
│ │ │ │ +following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5205723319-1">&lt;&lt;</span><span class="w"> </span><span class="n">BitStringExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="w"> </span><span class="p" data-group-id="5205723319-1">&gt;&gt;</span></code></pre><p><code class="inline">BitStringExpr</code> is an expression that evaluates to a bit string. If
│ │ │ │  <code class="inline">BitStringExpr</code> is a function call, it must be enclosed in parentheses. Each
│ │ │ │ -<code class="inline">Qualifier</code> is either a <strong>generator</strong> or a <strong>filter</strong>.</p><p>Map comprehensions construct maps. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9310320551-1">#{</span><span class="n">KeyExpr</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="9310320551-1">}</span></code></pre><p>Here, <code class="inline">KeyExpr</code> and <code class="inline">ValueExpr</code> are arbitrary expressions, and each <code class="inline">Qualifier</code>
│ │ │ │ +<code class="inline">Qualifier</code> is either a <strong>generator</strong> or a <strong>filter</strong>.</p><p>Map comprehensions construct maps. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8168745811-1">#{</span><span class="n">KeyExpr</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="8168745811-1">}</span></code></pre><p>Here, <code class="inline">KeyExpr</code> and <code class="inline">ValueExpr</code> are arbitrary expressions, and each <code class="inline">Qualifier</code>
│ │ │ │  is either a <strong>generator</strong> or a <strong>filter</strong>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Map comprehensions and map generators were introduced in Erlang/OTP 26.</p></section><p>There are three kinds of generators.</p><p>A <em>list generator</em> has the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">ListExpr</span></code></pre><p>where <code class="inline">ListExpr</code> is an expression that evaluates to a list of terms.</p><p>A <em>bit string generator</em> has the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">BitstringPattern</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="n">BitStringExpr</span></code></pre><p>where <code class="inline">BitStringExpr</code> is an expression that evaluates to a bit string.</p><p>A <em>map generator</em> has the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">KeyPattern</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">ValuePattern</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">MapExpression</span></code></pre><p>where <code class="inline">MapExpr</code> is an expression that evaluates to a map, or a map iterator
│ │ │ │  obtained by calling <a href="../../../lib/stdlib/doc/html/maps.html#iterator/1"><code class="inline">maps:iterator/1</code></a> or <a href="../../../lib/stdlib/doc/html/maps.html#iterator/2"><code class="inline">maps:iterator/2</code></a>.</p><p>A <em>filter</em> is an expression that evaluates to <code class="inline">true</code> or <code class="inline">false</code>.</p><p>The variables in the generator patterns shadow previously bound variables,
│ │ │ │  including variables bound in a previous generator pattern.</p><p>Variables bound in a generator expression are not visible outside the
│ │ │ │ -expression:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="2698181957-1">[</span><span class="p" data-group-id="2698181957-2">{</span><span class="n">E</span><span class="p">,</span><span class="n">L</span><span class="p" data-group-id="2698181957-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="o">=</span><span class="p" data-group-id="2698181957-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2698181957-3">]</span><span class="p" data-group-id="2698181957-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +expression:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9691511505-1">[</span><span class="p" data-group-id="9691511505-2">{</span><span class="n">E</span><span class="p">,</span><span class="n">L</span><span class="p" data-group-id="9691511505-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="o">=</span><span class="p" data-group-id="9691511505-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9691511505-3">]</span><span class="p" data-group-id="9691511505-1">]</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">* 1:5: variable &#39;L&#39; is unbound</span></code></pre><p>A <strong>list comprehension</strong> returns a list, where the list elements are the result
│ │ │ │  of evaluating <code class="inline">Expr</code> for each combination of generator elements for which all
│ │ │ │  filters are true.</p><p>A <strong>bit string comprehension</strong> returns a bit string, which is created by
│ │ │ │  concatenating the results of evaluating <code class="inline">BitStringExpr</code> for each combination of
│ │ │ │  bit string generator elements for which all filters are true.</p><p>A <strong>map comprehension</strong> returns a map, where the map elements are the result of
│ │ │ │  evaluating <code class="inline">KeyExpr</code> and <code class="inline">ValueExpr</code> for each combination of generator elements
│ │ │ │  for which all filters are true. If the key expressions are not unique, the last
│ │ │ │ -occurrence is stored in the map.</p><p><strong>Examples:</strong></p><p>Multiplying each element in a list by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="6796325278-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="6796325278-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="6796325278-2">]</span><span class="p" data-group-id="6796325278-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6796325278-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="6796325278-3">]</span></code></pre><p>Multiplying each byte in a binary by two, returning a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4844016875-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="4844016875-2">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="4844016875-2">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="4844016875-3">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4844016875-3">&gt;&gt;</span><span class="p" data-group-id="4844016875-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4844016875-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="4844016875-4">]</span></code></pre><p>Multiplying each byte in a binary by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="2700315060-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="2700315060-2">&lt;&lt;</span><span class="p" data-group-id="2700315060-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="2700315060-3">)</span><span class="p" data-group-id="2700315060-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="2700315060-4">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="2700315060-4">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="2700315060-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2700315060-5">&gt;&gt;</span><span class="w"> </span><span class="p" data-group-id="2700315060-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2700315060-6">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2700315060-6">&gt;&gt;</span></code></pre><p>Multiplying each element in a list by two, returning a binary:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7472594077-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="7472594077-2">&lt;&lt;</span><span class="p" data-group-id="7472594077-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="7472594077-3">)</span><span class="p" data-group-id="7472594077-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="7472594077-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7472594077-4">]</span><span class="w"> </span><span class="p" data-group-id="7472594077-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7472594077-5">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7472594077-5">&gt;&gt;</span></code></pre><p>Creating a mapping from an integer to its square:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5486640708-1">#{</span><span class="n">X</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5486640708-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5486640708-2">]</span><span class="p" data-group-id="5486640708-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5486640708-3">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="5486640708-3">}</span></code></pre><p>Multiplying the value of each element in a map by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0376665445-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">V</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="0376665445-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="0376665445-2">}</span><span class="p" data-group-id="0376665445-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0376665445-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="0376665445-3">}</span></code></pre><p>Filtering a list, keeping odd numbers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="1341241669-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="1341241669-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="1341241669-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="1341241669-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1341241669-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="1341241669-3">]</span></code></pre><p>Filtering a list, keeping only elements that match:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9456567239-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="9456567239-2">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9456567239-2">}</span><span class="o">=</span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9456567239-3">[</span><span class="p" data-group-id="9456567239-4">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9456567239-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9456567239-5">[</span><span class="ss">a</span><span class="p" data-group-id="9456567239-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9456567239-6">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="9456567239-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9456567239-7">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9456567239-7">}</span><span class="p" data-group-id="9456567239-3">]</span><span class="p" data-group-id="9456567239-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9456567239-8">[</span><span class="p" data-group-id="9456567239-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9456567239-9">}</span><span class="p">,</span><span class="p" data-group-id="9456567239-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9456567239-10">}</span><span class="p" data-group-id="9456567239-8">]</span></code></pre><p>Combining elements from two list generators:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9481751450-1">[</span><span class="p" data-group-id="9481751450-2">{</span><span class="n">P</span><span class="p">,</span><span class="n">Q</span><span class="p" data-group-id="9481751450-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9481751450-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="9481751450-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Q</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9481751450-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9481751450-4">]</span><span class="p" data-group-id="9481751450-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9481751450-5">[</span><span class="p" data-group-id="9481751450-6">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9481751450-6">}</span><span class="p">,</span><span class="p" data-group-id="9481751450-7">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9481751450-7">}</span><span class="p">,</span><span class="p" data-group-id="9481751450-8">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9481751450-8">}</span><span class="p">,</span><span class="p" data-group-id="9481751450-9">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9481751450-9">}</span><span class="p">,</span><span class="p" data-group-id="9481751450-10">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9481751450-10">}</span><span class="p">,</span><span class="p" data-group-id="9481751450-11">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9481751450-11">}</span><span class="p" data-group-id="9481751450-5">]</span></code></pre><p>More examples are provided in
│ │ │ │ +occurrence is stored in the map.</p><p><strong>Examples:</strong></p><p>Multiplying each element in a list by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="8478873692-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="8478873692-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8478873692-2">]</span><span class="p" data-group-id="8478873692-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8478873692-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8478873692-3">]</span></code></pre><p>Multiplying each byte in a binary by two, returning a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5441158475-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="5441158475-2">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="5441158475-2">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="5441158475-3">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5441158475-3">&gt;&gt;</span><span class="p" data-group-id="5441158475-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5441158475-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5441158475-4">]</span></code></pre><p>Multiplying each byte in a binary by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3039410428-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="3039410428-2">&lt;&lt;</span><span class="p" data-group-id="3039410428-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="3039410428-3">)</span><span class="p" data-group-id="3039410428-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="3039410428-4">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="3039410428-4">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="3039410428-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3039410428-5">&gt;&gt;</span><span class="w"> </span><span class="p" data-group-id="3039410428-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3039410428-6">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3039410428-6">&gt;&gt;</span></code></pre><p>Multiplying each element in a list by two, returning a binary:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="8994630854-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="8994630854-2">&lt;&lt;</span><span class="p" data-group-id="8994630854-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="8994630854-3">)</span><span class="p" data-group-id="8994630854-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="8994630854-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8994630854-4">]</span><span class="w"> </span><span class="p" data-group-id="8994630854-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8994630854-5">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8994630854-5">&gt;&gt;</span></code></pre><p>Creating a mapping from an integer to its square:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5697822159-1">#{</span><span class="n">X</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5697822159-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5697822159-2">]</span><span class="p" data-group-id="5697822159-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5697822159-3">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="5697822159-3">}</span></code></pre><p>Multiplying the value of each element in a map by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5158675814-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">V</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5158675814-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="5158675814-2">}</span><span class="p" data-group-id="5158675814-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5158675814-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="5158675814-3">}</span></code></pre><p>Filtering a list, keeping odd numbers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7162665593-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="7162665593-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7162665593-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7162665593-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7162665593-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7162665593-3">]</span></code></pre><p>Filtering a list, keeping only elements that match:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7408601314-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="7408601314-2">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7408601314-2">}</span><span class="o">=</span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="7408601314-3">[</span><span class="p" data-group-id="7408601314-4">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7408601314-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7408601314-5">[</span><span class="ss">a</span><span class="p" data-group-id="7408601314-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7408601314-6">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="7408601314-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7408601314-7">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7408601314-7">}</span><span class="p" data-group-id="7408601314-3">]</span><span class="p" data-group-id="7408601314-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7408601314-8">[</span><span class="p" data-group-id="7408601314-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="7408601314-9">}</span><span class="p">,</span><span class="p" data-group-id="7408601314-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7408601314-10">}</span><span class="p" data-group-id="7408601314-8">]</span></code></pre><p>Combining elements from two list generators:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5801078837-1">[</span><span class="p" data-group-id="5801078837-2">{</span><span class="n">P</span><span class="p">,</span><span class="n">Q</span><span class="p" data-group-id="5801078837-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5801078837-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="5801078837-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Q</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5801078837-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5801078837-4">]</span><span class="p" data-group-id="5801078837-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5801078837-5">[</span><span class="p" data-group-id="5801078837-6">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5801078837-6">}</span><span class="p">,</span><span class="p" data-group-id="5801078837-7">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5801078837-7">}</span><span class="p">,</span><span class="p" data-group-id="5801078837-8">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5801078837-8">}</span><span class="p">,</span><span class="p" data-group-id="5801078837-9">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5801078837-9">}</span><span class="p">,</span><span class="p" data-group-id="5801078837-10">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5801078837-10">}</span><span class="p">,</span><span class="p" data-group-id="5801078837-11">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5801078837-11">}</span><span class="p" data-group-id="5801078837-5">]</span></code></pre><p>More examples are provided in
│ │ │ │  <a href="../../../lib/../system/doc/html/list_comprehensions.xhtml">Programming Examples.</a></p><p>When there are no generators, a comprehension returns either a term constructed
│ │ │ │  from a single element (the result of evaluating <code class="inline">Expr</code>) if all filters are true,
│ │ │ │  or a term constructed from no elements (that is, <code class="inline">[]</code> for list comprehension,
│ │ │ │ -<code class="inline">&lt;&lt;&gt;&gt;</code> for a bit string comprehension, and <code class="inline">#{}</code> for a map comprehension).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3809317067-1">[</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="3809317067-2">(</span><span class="mi">2</span><span class="p" data-group-id="3809317067-2">)</span><span class="p" data-group-id="3809317067-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3809317067-3">[</span><span class="mi">2</span><span class="p" data-group-id="3809317067-3">]</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="3809317067-4">[</span><span class="ss">x</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="3809317067-5">(</span><span class="ss">x</span><span class="p" data-group-id="3809317067-5">)</span><span class="p" data-group-id="3809317067-4">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3809317067-6">[</span><span class="p" data-group-id="3809317067-6">]</span></code></pre><p>What happens when the filter expression does not evaluate to a boolean value
│ │ │ │ +<code class="inline">&lt;&lt;&gt;&gt;</code> for a bit string comprehension, and <code class="inline">#{}</code> for a map comprehension).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3550793984-1">[</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="3550793984-2">(</span><span class="mi">2</span><span class="p" data-group-id="3550793984-2">)</span><span class="p" data-group-id="3550793984-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3550793984-3">[</span><span class="mi">2</span><span class="p" data-group-id="3550793984-3">]</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="3550793984-4">[</span><span class="ss">x</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="3550793984-5">(</span><span class="ss">x</span><span class="p" data-group-id="3550793984-5">)</span><span class="p" data-group-id="3550793984-4">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3550793984-6">[</span><span class="p" data-group-id="3550793984-6">]</span></code></pre><p>What happens when the filter expression does not evaluate to a boolean value
│ │ │ │  depends on the expression:</p><ul><li>If the expression is a <a href="expressions.xhtml#guard-expressions">guard expression</a>,
│ │ │ │  failure to evaluate or evaluating to a non-boolean value is equivalent to
│ │ │ │  evaluating to <code class="inline">false</code>.</li><li>If the expression is not a guard expression and evaluates to a non-Boolean
│ │ │ │  value <code class="inline">Val</code>, an exception <code class="inline">{bad_filter, Val}</code> is triggered at runtime. If the
│ │ │ │  evaluation of the expression raises an exception, it is not caught by the
│ │ │ │ -comprehension.</li></ul><p><strong>Examples</strong> (using a guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7333567211-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7333567211-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7333567211-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7333567211-2">]</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="7333567211-3">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="7333567211-3">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7333567211-4">[</span><span class="p" data-group-id="7333567211-4">]</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="p" data-group-id="7333567211-5">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7333567211-5">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7333567211-6">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7333567211-6">]</span></code></pre><p><strong>Examples</strong> (using a non-guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4060631988-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="4060631988-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4060631988-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="4060631988-2">]</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="n">FaultyIsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4060631988-3">(</span><span class="n">E</span><span class="p" data-group-id="4060631988-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +comprehension.</li></ul><p><strong>Examples</strong> (using a guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7497060298-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7497060298-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7497060298-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7497060298-2">]</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="7497060298-3">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="7497060298-3">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7497060298-4">[</span><span class="p" data-group-id="7497060298-4">]</span><span class="gp unselectable">
│ │ │ │ +3&gt; </span><span class="p" data-group-id="7497060298-5">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7497060298-5">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7497060298-6">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7497060298-6">]</span></code></pre><p><strong>Examples</strong> (using a non-guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7562325406-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7562325406-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7562325406-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7562325406-2">]</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="n">FaultyIsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="7562325406-3">(</span><span class="n">E</span><span class="p" data-group-id="7562325406-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">42.17316486</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="p" data-group-id="4060631988-4">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">FaultyIsEven</span><span class="p" data-group-id="4060631988-5">(</span><span class="n">E</span><span class="p" data-group-id="4060631988-5">)</span><span class="p" data-group-id="4060631988-4">]</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="p" data-group-id="7562325406-4">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">FaultyIsEven</span><span class="p" data-group-id="7562325406-5">(</span><span class="n">E</span><span class="p" data-group-id="7562325406-5">)</span><span class="p" data-group-id="7562325406-4">]</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: bad filter 1</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="n">IsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4060631988-6">(</span><span class="n">E</span><span class="p" data-group-id="4060631988-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="n">IsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="7562325406-6">(</span><span class="n">E</span><span class="p" data-group-id="7562325406-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">42.17316486</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="p" data-group-id="4060631988-7">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="4060631988-8">(</span><span class="n">E</span><span class="p" data-group-id="4060631988-8">)</span><span class="p" data-group-id="4060631988-7">]</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="p" data-group-id="7562325406-7">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="7562325406-8">(</span><span class="n">E</span><span class="p" data-group-id="7562325406-8">)</span><span class="p" data-group-id="7562325406-7">]</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="gt">** exception error: an error occurred when evaluating an arithmetic expression
│ │ │ │       in operator  rem/2
│ │ │ │          called as a rem 2</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="p" data-group-id="4060631988-9">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="4060631988-10">(</span><span class="n">E</span><span class="p" data-group-id="4060631988-10">)</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="4060631988-11">(</span><span class="n">E</span><span class="p" data-group-id="4060631988-11">)</span><span class="p" data-group-id="4060631988-9">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4060631988-12">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="4060631988-12">]</span></code></pre><p><a href="" id="guards"></a></p><h2 id="guard-sequences" class="section-heading">
│ │ │ │ +6&gt; </span><span class="p" data-group-id="7562325406-9">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="7562325406-10">(</span><span class="n">E</span><span class="p" data-group-id="7562325406-10">)</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="7562325406-11">(</span><span class="n">E</span><span class="p" data-group-id="7562325406-11">)</span><span class="p" data-group-id="7562325406-9">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7562325406-12">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7562325406-12">]</span></code></pre><p><a href="" id="guards"></a></p><h2 id="guard-sequences" class="section-heading">
│ │ │ │    <a href="#guard-sequences" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Guard Sequences</span>
│ │ │ │  </h2>
│ │ │ │  <p>A <em>guard sequence</em> is a sequence of guards, separated by semicolon (<code class="inline">;</code>). The
│ │ │ │  guard sequence is true if at least one of the guards is true. (The remaining
│ │ │ ├── OEBPS/example.xhtml
│ │ │ │ @@ -36,14 +36,14 @@
│ │ │ │  
│ │ │ │  int bar(int y) {
│ │ │ │    return y*2;
│ │ │ │  }</code></pre><p>The functions are deliberately kept as simple as possible, for readability
│ │ │ │  reasons.</p><p>From an Erlang perspective, it is preferable to be able to call <code class="inline">foo</code> and <code class="inline">bar</code>
│ │ │ │  without having to bother about that they are C functions:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% Erlang code</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="n">Res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">complex</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="6757740207-1">(</span><span class="n">X</span><span class="p" data-group-id="6757740207-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">complex</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="8398774059-1">(</span><span class="n">X</span><span class="p" data-group-id="8398774059-1">)</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Here, the communication with C is hidden in the implementation of <code class="inline">complex.erl</code>.
│ │ │ │  In the following sections, it is shown how this module can be implemented using
│ │ │ │  the different interoperability mechanisms.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/events.xhtml
│ │ │ │ @@ -40,43 +40,43 @@
│ │ │ │  event handler.</p><h2 id="example" class="section-heading">
│ │ │ │    <a href="#example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Example</span>
│ │ │ │  </h2>
│ │ │ │  <p>The callback module for the event handler writing error messages to the terminal
│ │ │ │ -can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5515098167-1">(</span><span class="ss">terminal_logger</span><span class="p" data-group-id="5515098167-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5515098167-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="5515098167-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1958321330-1">(</span><span class="ss">terminal_logger</span><span class="p" data-group-id="1958321330-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="1958321330-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="1958321330-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5515098167-3">(</span><span class="p" data-group-id="5515098167-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5515098167-4">]</span><span class="p" data-group-id="5515098167-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1958321330-3">(</span><span class="p" data-group-id="1958321330-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1958321330-4">]</span><span class="p" data-group-id="1958321330-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="5515098167-5">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="5515098167-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5515098167-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5515098167-7">[</span><span class="p" data-group-id="5515098167-7">]</span><span class="p" data-group-id="5515098167-6">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="1958321330-5">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="1958321330-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1958321330-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1958321330-7">[</span><span class="p" data-group-id="1958321330-7">]</span><span class="p" data-group-id="1958321330-6">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="5515098167-8">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="5515098167-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5515098167-9">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5515098167-10">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="5515098167-10">]</span><span class="p" data-group-id="5515098167-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5515098167-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="5515098167-11">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="1958321330-8">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1958321330-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1958321330-9">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1958321330-10">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="1958321330-10">]</span><span class="p" data-group-id="1958321330-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1958321330-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1958321330-11">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="5515098167-12">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="5515098167-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="1958321330-12">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="1958321330-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The callback module for the event handler writing error messages to a file can
│ │ │ │ -look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5654082534-1">(</span><span class="ss">file_logger</span><span class="p" data-group-id="5654082534-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5654082534-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="5654082534-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8664386277-1">(</span><span class="ss">file_logger</span><span class="p" data-group-id="8664386277-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="8664386277-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="8664386277-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5654082534-3">(</span><span class="p" data-group-id="5654082534-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5654082534-4">]</span><span class="p" data-group-id="5654082534-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8664386277-3">(</span><span class="p" data-group-id="8664386277-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8664386277-4">]</span><span class="p" data-group-id="8664386277-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="5654082534-5">(</span><span class="n">File</span><span class="p" data-group-id="5654082534-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5654082534-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="5654082534-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="5654082534-7">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="5654082534-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5654082534-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="5654082534-8">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="5654082534-9">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="5654082534-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5654082534-10">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5654082534-11">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="5654082534-11">]</span><span class="p" data-group-id="5654082534-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5654082534-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="5654082534-12">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="8664386277-5">(</span><span class="n">File</span><span class="p" data-group-id="8664386277-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8664386277-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="8664386277-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="8664386277-7">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="8664386277-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8664386277-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="8664386277-8">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="8664386277-9">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="8664386277-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8664386277-10">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8664386277-11">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="8664386277-11">]</span><span class="p" data-group-id="8664386277-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8664386277-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="8664386277-12">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="5654082534-13">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="5654082534-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="5654082534-14">(</span><span class="n">Fd</span><span class="p" data-group-id="5654082534-14">)</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><p><a href="" id="mgr"></a></p><h2 id="starting-an-event-manager" class="section-heading">
│ │ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="8664386277-13">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="8664386277-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="8664386277-14">(</span><span class="n">Fd</span><span class="p" data-group-id="8664386277-14">)</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><p><a href="" id="mgr"></a></p><h2 id="starting-an-event-manager" class="section-heading">
│ │ │ │    <a href="#starting-an-event-manager" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting an Event Manager</span>
│ │ │ │  </h2>
│ │ │ │  <p>To start an event manager for handling errors, as described in the previous
│ │ │ │  example, call the following function:</p><pre><code class="text">gen_event:start_link({local, error_man})</code></pre><p><a href="../../../lib/stdlib/doc/html/gen_event.html#start_link/1"><code class="inline">gen_event:start_link/1</code></a> spawns and links to a new event manager process.</p><p>The argument, <code class="inline">{local, error_man}</code>, specifies the name under which the
│ │ │ │ @@ -89,57 +89,57 @@
│ │ │ │  manager that is not part of a supervision tree.</p><h2 id="adding-an-event-handler" class="section-heading">
│ │ │ │    <a href="#adding-an-event-handler" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Adding an Event Handler</span>
│ │ │ │  </h2>
│ │ │ │  <p>The following example shows how to start an event manager and add an event
│ │ │ │ -handler to it by using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="0690692741-1">(</span><span class="p" data-group-id="0690692741-2">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="0690692741-2">}</span><span class="p" data-group-id="0690692741-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0690692741-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.31</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="0690692741-3">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">add_handler</span><span class="p" data-group-id="0690692741-4">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0690692741-5">[</span><span class="p" data-group-id="0690692741-5">]</span><span class="p" data-group-id="0690692741-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +handler to it by using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4720694260-1">(</span><span class="p" data-group-id="4720694260-2">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="4720694260-2">}</span><span class="p" data-group-id="4720694260-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="4720694260-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.31</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="4720694260-3">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">add_handler</span><span class="p" data-group-id="4720694260-4">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4720694260-5">[</span><span class="p" data-group-id="4720694260-5">]</span><span class="p" data-group-id="4720694260-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>This function sends a message to the event manager registered as <code class="inline">error_man</code>,
│ │ │ │  telling it to add the event handler <code class="inline">terminal_logger</code>. The event manager calls
│ │ │ │  the callback function <code class="inline">terminal_logger:init([])</code>, where the argument <code class="inline">[]</code> is the
│ │ │ │  third argument to <code class="inline">add_handler</code>. <code class="inline">init/1</code> is expected to return <code class="inline">{ok, State}</code>,
│ │ │ │ -where <code class="inline">State</code> is the internal state of the event handler.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0357154813-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="0357154813-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0357154813-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0357154813-3">[</span><span class="p" data-group-id="0357154813-3">]</span><span class="p" data-group-id="0357154813-2">}</span><span class="p">.</span></code></pre><p>Here, <code class="inline">init/1</code> does not need any input data and ignores its argument. For
│ │ │ │ +where <code class="inline">State</code> is the internal state of the event handler.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="9390195860-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="9390195860-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9390195860-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9390195860-3">[</span><span class="p" data-group-id="9390195860-3">]</span><span class="p" data-group-id="9390195860-2">}</span><span class="p">.</span></code></pre><p>Here, <code class="inline">init/1</code> does not need any input data and ignores its argument. For
│ │ │ │  <code class="inline">terminal_logger</code>, the internal state is not used. For <code class="inline">file_logger</code>, the
│ │ │ │ -internal state is used to save the open file descriptor.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0124332177-1">(</span><span class="n">File</span><span class="p" data-group-id="0124332177-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0124332177-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="0124332177-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="0124332177-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="0124332177-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0124332177-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="0124332177-4">}</span><span class="p">.</span></code></pre><h2 id="notifying-about-events" class="section-heading">
│ │ │ │ +internal state is used to save the open file descriptor.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1100359202-1">(</span><span class="n">File</span><span class="p" data-group-id="1100359202-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1100359202-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="1100359202-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="1100359202-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="1100359202-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1100359202-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="1100359202-4">}</span><span class="p">.</span></code></pre><h2 id="notifying-about-events" class="section-heading">
│ │ │ │    <a href="#notifying-about-events" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Notifying about Events</span>
│ │ │ │  </h2>
│ │ │ │  <pre><code class="text">3&gt; gen_event:notify(error_man, no_reply).
│ │ │ │  ***Error*** no_reply
│ │ │ │  ok</code></pre><p><code class="inline">error_man</code> is the name of the event manager and <code class="inline">no_reply</code> is the event.</p><p>The event is made into a message and sent to the event manager. When the event
│ │ │ │  is received, the event manager calls <code class="inline">handle_event(Event, State)</code> for each
│ │ │ │  installed event handler, in the same order as they were added. The function is
│ │ │ │  expected to return a tuple <code class="inline">{ok,State1}</code>, where <code class="inline">State1</code> is a new value for the
│ │ │ │ -state of the event handler.</p><p>In <code class="inline">terminal_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="8955624086-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="8955624086-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8955624086-2">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8955624086-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="8955624086-3">]</span><span class="p" data-group-id="8955624086-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="8955624086-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="8955624086-4">}</span><span class="p">.</span></code></pre><p>In <code class="inline">file_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="4517933307-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="4517933307-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4517933307-2">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4517933307-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="4517933307-3">]</span><span class="p" data-group-id="4517933307-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4517933307-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="4517933307-4">}</span><span class="p">.</span></code></pre><h2 id="deleting-an-event-handler" class="section-heading">
│ │ │ │ +state of the event handler.</p><p>In <code class="inline">terminal_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="7014398610-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7014398610-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7014398610-2">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7014398610-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="7014398610-3">]</span><span class="p" data-group-id="7014398610-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7014398610-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7014398610-4">}</span><span class="p">.</span></code></pre><p>In <code class="inline">file_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="9565695856-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="9565695856-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9565695856-2">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9565695856-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="9565695856-3">]</span><span class="p" data-group-id="9565695856-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9565695856-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="9565695856-4">}</span><span class="p">.</span></code></pre><h2 id="deleting-an-event-handler" class="section-heading">
│ │ │ │    <a href="#deleting-an-event-handler" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Deleting an Event Handler</span>
│ │ │ │  </h2>
│ │ │ │ -<pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">delete_handler</span><span class="p" data-group-id="4985464799-1">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4985464799-2">[</span><span class="p" data-group-id="4985464799-2">]</span><span class="p" data-group-id="4985464799-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">delete_handler</span><span class="p" data-group-id="2863921853-1">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2863921853-2">[</span><span class="p" data-group-id="2863921853-2">]</span><span class="p" data-group-id="2863921853-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><p>This function sends a message to the event manager registered as <code class="inline">error_man</code>,
│ │ │ │  telling it to delete the event handler <code class="inline">terminal_logger</code>. The event manager
│ │ │ │  calls the callback function <code class="inline">terminal_logger:terminate([], State)</code>, where the
│ │ │ │  argument <code class="inline">[]</code> is the third argument to <code class="inline">delete_handler</code>. <code class="inline">terminate/2</code> is to be
│ │ │ │  the opposite of <code class="inline">init/1</code> and do any necessary cleaning up. Its return value is
│ │ │ │ -ignored.</p><p>For <code class="inline">terminal_logger</code>, no cleaning up is necessary:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="5364555656-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="5364555656-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>For <code class="inline">file_logger</code>, the file descriptor opened in <code class="inline">init</code> must be closed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="2228035364-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2228035364-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="2228035364-2">(</span><span class="n">Fd</span><span class="p" data-group-id="2228035364-2">)</span><span class="p">.</span></code></pre><h2 id="stopping" class="section-heading">
│ │ │ │ +ignored.</p><p>For <code class="inline">terminal_logger</code>, no cleaning up is necessary:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="6215081256-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="6215081256-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>For <code class="inline">file_logger</code>, the file descriptor opened in <code class="inline">init</code> must be closed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="9785967165-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="9785967165-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9785967165-2">(</span><span class="n">Fd</span><span class="p" data-group-id="9785967165-2">)</span><span class="p">.</span></code></pre><h2 id="stopping" class="section-heading">
│ │ │ │    <a href="#stopping" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Stopping</span>
│ │ │ │  </h2>
│ │ │ │  <p>When an event manager is stopped, it gives each of the installed event handlers
│ │ │ │  the chance to clean up by calling <code class="inline">terminate/2</code>, the same way as when deleting a
│ │ │ │ @@ -154,29 +154,29 @@
│ │ │ │  this is done is defined by a <a href="sup_princ.xhtml#shutdown">shutdown strategy</a> set in
│ │ │ │  the supervisor.</p><h3 id="standalone-event-managers" class="section-heading">
│ │ │ │    <a href="#standalone-event-managers" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Standalone Event Managers</span>
│ │ │ │  </h3>
│ │ │ │ -<p>An event manager can also be stopped by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="5201281321-1">(</span><span class="ss">error_man</span><span class="p" data-group-id="5201281321-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>An event manager can also be stopped by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="7559592080-1">(</span><span class="ss">error_man</span><span class="p" data-group-id="7559592080-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span></code></pre><h2 id="handling-other-messages" class="section-heading">
│ │ │ │    <a href="#handling-other-messages" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Handling Other Messages</span>
│ │ │ │  </h2>
│ │ │ │  <p>If the <code class="inline">gen_event</code> process is to be able to receive other messages
│ │ │ │  than events, the callback function <code class="inline">handle_info(Info, State)</code> must be
│ │ │ │  implemented to handle them. Examples of other messages are exit
│ │ │ │  messages if the event manager is linked to other processes than the
│ │ │ │  supervisor (for example via <a href="../../../lib/stdlib/doc/html/gen_event.html#add_sup_handler/3"><code class="inline">gen_event:add_sup_handler/3</code></a>) and is
│ │ │ │ -trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="1924119686-1">(</span><span class="p" data-group-id="1924119686-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="1924119686-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1924119686-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="0562652891-1">(</span><span class="p" data-group-id="0562652891-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="0562652891-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="0562652891-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Code to handle exits here.</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1924119686-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="1924119686-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="6120105661-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="6120105661-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0562652891-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="0562652891-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="3340638690-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="3340638690-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Code to convert state (and more) during code change.</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6120105661-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="6120105661-2">}</span><span class="p">.</span></code></pre>
│ │ │ │ +    </span><span class="p" data-group-id="3340638690-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="3340638690-2">}</span><span class="p">.</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/errors.xhtml
│ │ │ │ @@ -56,22 +56,22 @@
│ │ │ │  classes, with different origins. The <a href="expressions.xhtml#try">try</a> expression can
│ │ │ │  distinguish between the different classes, whereas the
│ │ │ │  <a href="expressions.xhtml#catch-and-throw">catch</a> expression cannot. <code class="inline">try</code> and <code class="inline">catch</code> are described
│ │ │ │  in <a href="expressions.xhtml">Expressions</a>.</p><table><thead><tr><th style="text-align: left;"><em>Class</em></th><th style="text-align: left;"><em>Origin</em></th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">error</code></td><td style="text-align: left;">Run-time error, for example, <code class="inline">1+a</code>, or the process called <a href="../../../lib/../erts/doc/html/erlang.html#error/1"><code class="inline">error/1</code></a></td></tr><tr><td style="text-align: left;"><code class="inline">exit</code></td><td style="text-align: left;">The process called <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit/1</code></a></td></tr><tr><td style="text-align: left;"><code class="inline">throw</code></td><td style="text-align: left;">The process called <a href="../../../lib/../erts/doc/html/erlang.html#throw/1"><code class="inline">throw/1</code></a></td></tr></tbody></table><p><em>Table: Exception Classes.</em></p><p>All of the above exceptions can also be generated by calling <a href="../../../lib/../erts/doc/html/erlang.html#raise/3"><code class="inline">erlang:raise/3</code></a>.</p><p>An exception consists of its class, an exit reason (see
│ │ │ │  <a href="errors.xhtml#exit_reasons">Exit Reason</a>), and a stack trace (which aids in finding
│ │ │ │  the code location of the exception).</p><p>The stack trace can be bound to a variable from within a <code class="inline">try</code> expression for
│ │ │ │  any exception class, or as part of the exit reason when a run-time error is
│ │ │ │ -caught by a <code class="inline">catch</code>. Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="7092531480-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="7092531480-2">{</span><span class="ss">test</span><span class="p">,</span><span class="n">Stacktrace</span><span class="p" data-group-id="7092531480-2">}</span><span class="p" data-group-id="7092531480-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7092531480-3">(</span><span class="k">catch</span><span class="w"> </span><span class="nf">error</span><span class="p" data-group-id="7092531480-4">(</span><span class="ss">test</span><span class="p" data-group-id="7092531480-4">)</span><span class="p" data-group-id="7092531480-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Stacktrace</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7092531480-5">[</span><span class="p" data-group-id="7092531480-6">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="7092531480-7">[</span><span class="p" data-group-id="7092531480-7">]</span><span class="p" data-group-id="7092531480-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7092531480-8">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="7092531480-9">[</span><span class="p" data-group-id="7092531480-9">]</span><span class="p" data-group-id="7092531480-8">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7092531480-5">]</span><span class="gp unselectable">
│ │ │ │ -&gt; </span><span class="k">try</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="7092531480-10">(</span><span class="ss">test</span><span class="p" data-group-id="7092531480-10">)</span><span class="w"> </span><span class="k">catch</span><span class="w"> </span><span class="n">Class</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stacktrace</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Stacktrace</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7092531480-11">[</span><span class="p" data-group-id="7092531480-12">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="7092531480-13">[</span><span class="p" data-group-id="7092531480-13">]</span><span class="p" data-group-id="7092531480-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7092531480-14">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="7092531480-15">[</span><span class="p" data-group-id="7092531480-15">]</span><span class="p" data-group-id="7092531480-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7092531480-11">]</span></code></pre><p><a href="" id="stacktrace"></a></p><h3 id="the-call-stack-back-trace-stacktrace" class="section-heading">
│ │ │ │ +caught by a <code class="inline">catch</code>. Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="5388433146-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="5388433146-2">{</span><span class="ss">test</span><span class="p">,</span><span class="n">Stacktrace</span><span class="p" data-group-id="5388433146-2">}</span><span class="p" data-group-id="5388433146-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5388433146-3">(</span><span class="k">catch</span><span class="w"> </span><span class="nf">error</span><span class="p" data-group-id="5388433146-4">(</span><span class="ss">test</span><span class="p" data-group-id="5388433146-4">)</span><span class="p" data-group-id="5388433146-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Stacktrace</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5388433146-5">[</span><span class="p" data-group-id="5388433146-6">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="5388433146-7">[</span><span class="p" data-group-id="5388433146-7">]</span><span class="p" data-group-id="5388433146-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5388433146-8">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="5388433146-9">[</span><span class="p" data-group-id="5388433146-9">]</span><span class="p" data-group-id="5388433146-8">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5388433146-5">]</span><span class="gp unselectable">
│ │ │ │ +&gt; </span><span class="k">try</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="5388433146-10">(</span><span class="ss">test</span><span class="p" data-group-id="5388433146-10">)</span><span class="w"> </span><span class="k">catch</span><span class="w"> </span><span class="n">Class</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stacktrace</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Stacktrace</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5388433146-11">[</span><span class="p" data-group-id="5388433146-12">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="5388433146-13">[</span><span class="p" data-group-id="5388433146-13">]</span><span class="p" data-group-id="5388433146-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5388433146-14">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="5388433146-15">[</span><span class="p" data-group-id="5388433146-15">]</span><span class="p" data-group-id="5388433146-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5388433146-11">]</span></code></pre><p><a href="" id="stacktrace"></a></p><h3 id="the-call-stack-back-trace-stacktrace" class="section-heading">
│ │ │ │    <a href="#the-call-stack-back-trace-stacktrace" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">The call-stack back trace (stacktrace)</span>
│ │ │ │  </h3>
│ │ │ │  <p>The stack back-trace (<a href="../../../lib/../erts/doc/html/erlang.html#t:stacktrace/0"><em>stacktrace</em></a>) is a list that
│ │ │ │  contains <code class="inline">{Module, Function, Arity, ExtraInfo}</code> and/or <code class="inline">{Fun, Arity, ExtraInfo}</code>
│ │ │ ├── OEBPS/error_logging.xhtml
│ │ │ │ @@ -48,36 +48,36 @@
│ │ │ │  reports and other error and information reports are by default logged through
│ │ │ │  the log handler which is set up when the Kernel application is started.</p><p>Prior to Erlang/OTP 21.0, supervisor, crash, and progress reports were only
│ │ │ │  logged when the SASL application was running. This behaviour can, for backwards
│ │ │ │  compatibility, be enabled by setting the Kernel configuration parameter
│ │ │ │  <a href="../../../lib/kernel/doc/html/kernel_app.xhtml#logger_sasl_compatible"><code class="inline">logger_sasl_compatible</code></a> to
│ │ │ │  <code class="inline">true</code>. For more information, see
│ │ │ │  <a href="../../../lib/sasl/doc/html/error_logging.xhtml">SASL Error Logging</a> in the SASL User's Guide.</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -kernel logger_level info</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">21</span><span class="w"> </span><span class="p" data-group-id="4981566750-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">10.0</span><span class="p" data-group-id="4981566750-1">]</span><span class="w"> </span><span class="p" data-group-id="4981566750-2">[</span><span class="ss">source</span><span class="o">-</span><span class="mi">13</span><span class="ss">c50db</span><span class="p" data-group-id="4981566750-2">]</span><span class="w"> </span><span class="p" data-group-id="4981566750-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="4981566750-3">]</span><span class="w"> </span><span class="p" data-group-id="4981566750-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="4981566750-4">]</span><span class="w"> </span><span class="p" data-group-id="4981566750-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="4981566750-5">]</span><span class="w"> </span><span class="p" data-group-id="4981566750-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="4981566750-6">]</span><span class="w"> </span><span class="p" data-group-id="4981566750-7">[</span><span class="ss">hipe</span><span class="p" data-group-id="4981566750-7">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">21</span><span class="w"> </span><span class="p" data-group-id="9136269094-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">10.0</span><span class="p" data-group-id="9136269094-1">]</span><span class="w"> </span><span class="p" data-group-id="9136269094-2">[</span><span class="ss">source</span><span class="o">-</span><span class="mi">13</span><span class="ss">c50db</span><span class="p" data-group-id="9136269094-2">]</span><span class="w"> </span><span class="p" data-group-id="9136269094-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="9136269094-3">]</span><span class="w"> </span><span class="p" data-group-id="9136269094-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="9136269094-4">]</span><span class="w"> </span><span class="p" data-group-id="9136269094-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="9136269094-5">]</span><span class="w"> </span><span class="p" data-group-id="9136269094-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="9136269094-6">]</span><span class="w"> </span><span class="p" data-group-id="9136269094-7">[</span><span class="ss">hipe</span><span class="p" data-group-id="9136269094-7">]</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.916404</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │ │      </span><span class="nc">application</span><span class="p">:</span><span class="w"> </span><span class="ss">kernel</span><span class="w">
│ │ │ │      </span><span class="nc">started_at</span><span class="p">:</span><span class="w"> </span><span class="ss">nonode@nohost</span><span class="w">
│ │ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.922908</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │ │      </span><span class="nc">application</span><span class="p">:</span><span class="w"> </span><span class="ss">stdlib</span><span class="w">
│ │ │ │      </span><span class="nc">started_at</span><span class="p">:</span><span class="w"> </span><span class="ss">nonode@nohost</span><span class="w">
│ │ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.925755</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="4981566750-8">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="4981566750-8">}</span><span class="w">
│ │ │ │ -    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="4981566750-9">[</span><span class="p" data-group-id="4981566750-10">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.74</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="4981566750-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-11">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_sup</span><span class="p" data-group-id="4981566750-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-12">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="4981566750-13">{</span><span class="ss">disk_log_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="4981566750-14">[</span><span class="p" data-group-id="4981566750-14">]</span><span class="p" data-group-id="4981566750-13">}</span><span class="p" data-group-id="4981566750-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-15">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="4981566750-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-16">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">1000</span><span class="p" data-group-id="4981566750-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-17">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">supervisor</span><span class="p" data-group-id="4981566750-17">}</span><span class="p" data-group-id="4981566750-9">]</span><span class="w">
│ │ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="9136269094-8">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="9136269094-8">}</span><span class="w">
│ │ │ │ +    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="9136269094-9">[</span><span class="p" data-group-id="9136269094-10">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.74</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="9136269094-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-11">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_sup</span><span class="p" data-group-id="9136269094-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-12">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="9136269094-13">{</span><span class="ss">disk_log_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="9136269094-14">[</span><span class="p" data-group-id="9136269094-14">]</span><span class="p" data-group-id="9136269094-13">}</span><span class="p" data-group-id="9136269094-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-15">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="9136269094-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-16">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">1000</span><span class="p" data-group-id="9136269094-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-17">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">supervisor</span><span class="p" data-group-id="9136269094-17">}</span><span class="p" data-group-id="9136269094-9">]</span><span class="w">
│ │ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.926056</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="4981566750-18">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="4981566750-18">}</span><span class="w">
│ │ │ │ -    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="4981566750-19">[</span><span class="p" data-group-id="4981566750-20">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.75</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="4981566750-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-21">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_server</span><span class="p" data-group-id="4981566750-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-22">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="4981566750-23">{</span><span class="ss">disk_log_server</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="4981566750-24">[</span><span class="p" data-group-id="4981566750-24">]</span><span class="p" data-group-id="4981566750-23">}</span><span class="p" data-group-id="4981566750-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-25">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="4981566750-25">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-26">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">2000</span><span class="p" data-group-id="4981566750-26">}</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="4981566750-27">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">worker</span><span class="p" data-group-id="4981566750-27">}</span><span class="p" data-group-id="4981566750-19">]</span><span class="w">
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V10</span><span class="p">.</span><span class="mi">0</span><span class="w">  </span><span class="p" data-group-id="4981566750-28">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="4981566750-28">)</span><span class="w">
│ │ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="9136269094-18">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="9136269094-18">}</span><span class="w">
│ │ │ │ +    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="9136269094-19">[</span><span class="p" data-group-id="9136269094-20">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.75</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="9136269094-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-21">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_server</span><span class="p" data-group-id="9136269094-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-22">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="9136269094-23">{</span><span class="ss">disk_log_server</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="9136269094-24">[</span><span class="p" data-group-id="9136269094-24">]</span><span class="p" data-group-id="9136269094-23">}</span><span class="p" data-group-id="9136269094-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-25">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="9136269094-25">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-26">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">2000</span><span class="p" data-group-id="9136269094-26">}</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9136269094-27">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">worker</span><span class="p" data-group-id="9136269094-27">}</span><span class="p" data-group-id="9136269094-19">]</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V10</span><span class="p">.</span><span class="mi">0</span><span class="w">  </span><span class="p" data-group-id="9136269094-28">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="9136269094-28">)</span><span class="w">
│ │ │ │  </span><span class="mi">1</span><span class="o">&gt;</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/erl_interface.xhtml
│ │ │ │ @@ -25,119 +25,119 @@
│ │ │ │  to read the port example in <a href="c_port.xhtml">Ports</a> before reading this section.</p><h2 id="erlang-program" class="section-heading">
│ │ │ │    <a href="#erlang-program" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Erlang Program</span>
│ │ │ │  </h2>
│ │ │ │  <p>The following example shows an Erlang program communicating with a C program
│ │ │ │ -over a plain port with home made encoding:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0518709469-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="0518709469-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0518709469-2">(</span><span class="p" data-group-id="0518709469-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0518709469-3">]</span><span class="p" data-group-id="0518709469-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0518709469-4">(</span><span class="p" data-group-id="0518709469-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0518709469-5">]</span><span class="p" data-group-id="0518709469-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="0518709469-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="0518709469-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="0518709469-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0518709469-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="0518709469-8">]</span><span class="p" data-group-id="0518709469-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="0518709469-9">(</span><span class="p" data-group-id="0518709469-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +over a plain port with home made encoding:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1577788139-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="1577788139-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1577788139-2">(</span><span class="p" data-group-id="1577788139-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1577788139-3">]</span><span class="p" data-group-id="1577788139-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1577788139-4">(</span><span class="p" data-group-id="1577788139-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1577788139-5">]</span><span class="p" data-group-id="1577788139-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1577788139-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="1577788139-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1577788139-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1577788139-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="1577788139-8">]</span><span class="p" data-group-id="1577788139-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="1577788139-9">(</span><span class="p" data-group-id="1577788139-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="0518709469-10">(</span><span class="n">X</span><span class="p" data-group-id="0518709469-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="0518709469-11">(</span><span class="p" data-group-id="0518709469-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="0518709469-12">}</span><span class="p" data-group-id="0518709469-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="0518709469-13">(</span><span class="n">Y</span><span class="p" data-group-id="0518709469-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="0518709469-14">(</span><span class="p" data-group-id="0518709469-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0518709469-15">}</span><span class="p" data-group-id="0518709469-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="1577788139-10">(</span><span class="n">X</span><span class="p" data-group-id="1577788139-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="1577788139-11">(</span><span class="p" data-group-id="1577788139-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1577788139-12">}</span><span class="p" data-group-id="1577788139-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="1577788139-13">(</span><span class="n">Y</span><span class="p" data-group-id="1577788139-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="1577788139-14">(</span><span class="p" data-group-id="1577788139-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1577788139-15">}</span><span class="p" data-group-id="1577788139-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="0518709469-16">(</span><span class="n">Msg</span><span class="p" data-group-id="0518709469-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0518709469-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0518709469-18">(</span><span class="p" data-group-id="0518709469-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="0518709469-17">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="1577788139-16">(</span><span class="n">Msg</span><span class="p" data-group-id="1577788139-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1577788139-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1577788139-18">(</span><span class="p" data-group-id="1577788139-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1577788139-17">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="0518709469-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="0518709469-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="1577788139-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="1577788139-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="0518709469-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="0518709469-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="0518709469-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0518709469-22">(</span><span class="p" data-group-id="0518709469-22">)</span><span class="p" data-group-id="0518709469-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="0518709469-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="0518709469-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="0518709469-24">(</span><span class="p" data-group-id="0518709469-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="0518709469-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0518709469-26">[</span><span class="p" data-group-id="0518709469-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="0518709469-27">}</span><span class="p" data-group-id="0518709469-26">]</span><span class="p" data-group-id="0518709469-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="0518709469-28">(</span><span class="n">Port</span><span class="p" data-group-id="0518709469-28">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="1577788139-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="1577788139-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="1577788139-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1577788139-22">(</span><span class="p" data-group-id="1577788139-22">)</span><span class="p" data-group-id="1577788139-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="1577788139-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="1577788139-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="1577788139-24">(</span><span class="p" data-group-id="1577788139-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="1577788139-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1577788139-26">[</span><span class="p" data-group-id="1577788139-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="1577788139-27">}</span><span class="p" data-group-id="1577788139-26">]</span><span class="p" data-group-id="1577788139-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="1577788139-28">(</span><span class="n">Port</span><span class="p" data-group-id="1577788139-28">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="0518709469-29">(</span><span class="n">Port</span><span class="p" data-group-id="0518709469-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="1577788139-29">(</span><span class="n">Port</span><span class="p" data-group-id="1577788139-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="0518709469-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="0518709469-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0518709469-31">{</span><span class="nf">self</span><span class="p" data-group-id="0518709469-32">(</span><span class="p" data-group-id="0518709469-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0518709469-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="0518709469-34">(</span><span class="n">Msg</span><span class="p" data-group-id="0518709469-34">)</span><span class="p" data-group-id="0518709469-33">}</span><span class="p" data-group-id="0518709469-31">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="1577788139-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1577788139-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1577788139-31">{</span><span class="nf">self</span><span class="p" data-group-id="1577788139-32">(</span><span class="p" data-group-id="1577788139-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1577788139-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="1577788139-34">(</span><span class="n">Msg</span><span class="p" data-group-id="1577788139-34">)</span><span class="p" data-group-id="1577788139-33">}</span><span class="p" data-group-id="1577788139-31">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="0518709469-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0518709469-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0518709469-36">}</span><span class="p" data-group-id="0518709469-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0518709469-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="0518709469-38">(</span><span class="n">Data</span><span class="p" data-group-id="0518709469-38">)</span><span class="p" data-group-id="0518709469-37">}</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="1577788139-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1577788139-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1577788139-36">}</span><span class="p" data-group-id="1577788139-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1577788139-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="1577788139-38">(</span><span class="n">Data</span><span class="p" data-group-id="1577788139-38">)</span><span class="p" data-group-id="1577788139-37">}</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="0518709469-39">(</span><span class="n">Port</span><span class="p" data-group-id="0518709469-39">)</span><span class="p">;</span><span class="w">
│ │ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="1577788139-39">(</span><span class="n">Port</span><span class="p" data-group-id="1577788139-39">)</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0518709469-40">{</span><span class="nf">self</span><span class="p" data-group-id="0518709469-41">(</span><span class="p" data-group-id="0518709469-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="0518709469-40">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1577788139-40">{</span><span class="nf">self</span><span class="p" data-group-id="1577788139-41">(</span><span class="p" data-group-id="1577788139-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="1577788139-40">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="0518709469-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="0518709469-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="0518709469-43">(</span><span class="ss">normal</span><span class="p" data-group-id="0518709469-43">)</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="1577788139-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="1577788139-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="1577788139-43">(</span><span class="ss">normal</span><span class="p" data-group-id="1577788139-43">)</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="0518709469-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="0518709469-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="0518709469-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="0518709469-45">)</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="1577788139-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="1577788139-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="1577788139-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="1577788139-45">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="0518709469-46">(</span><span class="p" data-group-id="0518709469-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="0518709469-47">}</span><span class="p" data-group-id="0518709469-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0518709469-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="0518709469-48">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="0518709469-49">(</span><span class="p" data-group-id="0518709469-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0518709469-50">}</span><span class="p" data-group-id="0518709469-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0518709469-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0518709469-51">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="1577788139-46">(</span><span class="p" data-group-id="1577788139-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1577788139-47">}</span><span class="p" data-group-id="1577788139-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1577788139-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1577788139-48">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="1577788139-49">(</span><span class="p" data-group-id="1577788139-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1577788139-50">}</span><span class="p" data-group-id="1577788139-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1577788139-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1577788139-51">]</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="0518709469-52">(</span><span class="p" data-group-id="0518709469-53">[</span><span class="n">Int</span><span class="p" data-group-id="0518709469-53">]</span><span class="p" data-group-id="0518709469-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>There are two differences when using Erl_Interface on the C side compared to the
│ │ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="1577788139-52">(</span><span class="p" data-group-id="1577788139-53">[</span><span class="n">Int</span><span class="p" data-group-id="1577788139-53">]</span><span class="p" data-group-id="1577788139-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>There are two differences when using Erl_Interface on the C side compared to the
│ │ │ │  example in <a href="c_port.xhtml">Ports</a>, using only the plain port:</p><ul><li>As Erl_Interface operates on the Erlang external term format, the port must be
│ │ │ │  set to use binaries.</li><li>Instead of inventing an encoding/decoding scheme, the
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#term_to_binary/1"><code class="inline">term_to_binary/1</code></a> and
│ │ │ │ -<a href="../../../lib/../erts/doc/html/erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a> BIFs are to be used.</li></ul><p>That is:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="6994020176-1">(</span><span class="p" data-group-id="6994020176-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="6994020176-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6994020176-3">[</span><span class="p" data-group-id="6994020176-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6994020176-4">}</span><span class="p" data-group-id="6994020176-3">]</span><span class="p" data-group-id="6994020176-1">)</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="9123487719-1">(</span><span class="p" data-group-id="9123487719-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="9123487719-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9123487719-3">[</span><span class="p" data-group-id="9123487719-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="9123487719-4">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="9123487719-3">]</span><span class="p" data-group-id="9123487719-1">)</span></code></pre><p>And:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8765017046-1">{</span><span class="nf">self</span><span class="p" data-group-id="8765017046-2">(</span><span class="p" data-group-id="8765017046-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8765017046-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="8765017046-4">(</span><span class="n">Msg</span><span class="p" data-group-id="8765017046-4">)</span><span class="p" data-group-id="8765017046-3">}</span><span class="p" data-group-id="8765017046-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ +<a href="../../../lib/../erts/doc/html/erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a> BIFs are to be used.</li></ul><p>That is:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="9074839135-1">(</span><span class="p" data-group-id="9074839135-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="9074839135-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9074839135-3">[</span><span class="p" data-group-id="9074839135-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="9074839135-4">}</span><span class="p" data-group-id="9074839135-3">]</span><span class="p" data-group-id="9074839135-1">)</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="3524911915-1">(</span><span class="p" data-group-id="3524911915-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="3524911915-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3524911915-3">[</span><span class="p" data-group-id="3524911915-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3524911915-4">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="3524911915-3">]</span><span class="p" data-group-id="3524911915-1">)</span></code></pre><p>And:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0402362429-1">{</span><span class="nf">self</span><span class="p" data-group-id="0402362429-2">(</span><span class="p" data-group-id="0402362429-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0402362429-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="0402362429-4">(</span><span class="n">Msg</span><span class="p" data-group-id="0402362429-4">)</span><span class="p" data-group-id="0402362429-3">}</span><span class="p" data-group-id="0402362429-1">}</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="8765017046-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8765017046-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8765017046-6">}</span><span class="p" data-group-id="8765017046-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8765017046-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="8765017046-8">(</span><span class="n">Data</span><span class="p" data-group-id="8765017046-8">)</span><span class="p" data-group-id="8765017046-7">}</span><span class="w">
│ │ │ │ -</span><span class="k">end</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7999922392-1">{</span><span class="nf">self</span><span class="p" data-group-id="7999922392-2">(</span><span class="p" data-group-id="7999922392-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7999922392-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="7999922392-4">(</span><span class="n">Msg</span><span class="p" data-group-id="7999922392-4">)</span><span class="p" data-group-id="7999922392-3">}</span><span class="p" data-group-id="7999922392-1">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="0402362429-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0402362429-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0402362429-6">}</span><span class="p" data-group-id="0402362429-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0402362429-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="0402362429-8">(</span><span class="n">Data</span><span class="p" data-group-id="0402362429-8">)</span><span class="p" data-group-id="0402362429-7">}</span><span class="w">
│ │ │ │ +</span><span class="k">end</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6453585060-1">{</span><span class="nf">self</span><span class="p" data-group-id="6453585060-2">(</span><span class="p" data-group-id="6453585060-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6453585060-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="6453585060-4">(</span><span class="n">Msg</span><span class="p" data-group-id="6453585060-4">)</span><span class="p" data-group-id="6453585060-3">}</span><span class="p" data-group-id="6453585060-1">}</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="7999922392-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7999922392-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7999922392-6">}</span><span class="p" data-group-id="7999922392-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7999922392-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="7999922392-8">(</span><span class="n">Data</span><span class="p" data-group-id="7999922392-8">)</span><span class="p" data-group-id="7999922392-7">}</span><span class="w">
│ │ │ │ -</span><span class="k">end</span></code></pre><p>The resulting Erlang program is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2999920143-1">(</span><span class="ss">complex2</span><span class="p" data-group-id="2999920143-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2999920143-2">(</span><span class="p" data-group-id="2999920143-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2999920143-3">]</span><span class="p" data-group-id="2999920143-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2999920143-4">(</span><span class="p" data-group-id="2999920143-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2999920143-5">]</span><span class="p" data-group-id="2999920143-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="2999920143-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="2999920143-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="2999920143-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2999920143-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="2999920143-8">]</span><span class="p" data-group-id="2999920143-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="2999920143-9">(</span><span class="p" data-group-id="2999920143-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="6453585060-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6453585060-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6453585060-6">}</span><span class="p" data-group-id="6453585060-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6453585060-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="6453585060-8">(</span><span class="n">Data</span><span class="p" data-group-id="6453585060-8">)</span><span class="p" data-group-id="6453585060-7">}</span><span class="w">
│ │ │ │ +</span><span class="k">end</span></code></pre><p>The resulting Erlang program is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5716519167-1">(</span><span class="ss">complex2</span><span class="p" data-group-id="5716519167-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5716519167-2">(</span><span class="p" data-group-id="5716519167-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5716519167-3">]</span><span class="p" data-group-id="5716519167-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5716519167-4">(</span><span class="p" data-group-id="5716519167-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5716519167-5">]</span><span class="p" data-group-id="5716519167-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="5716519167-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="5716519167-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="5716519167-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5716519167-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="5716519167-8">]</span><span class="p" data-group-id="5716519167-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="5716519167-9">(</span><span class="p" data-group-id="5716519167-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="2999920143-10">(</span><span class="n">X</span><span class="p" data-group-id="2999920143-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="2999920143-11">(</span><span class="p" data-group-id="2999920143-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2999920143-12">}</span><span class="p" data-group-id="2999920143-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="2999920143-13">(</span><span class="n">Y</span><span class="p" data-group-id="2999920143-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="2999920143-14">(</span><span class="p" data-group-id="2999920143-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2999920143-15">}</span><span class="p" data-group-id="2999920143-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="5716519167-10">(</span><span class="n">X</span><span class="p" data-group-id="5716519167-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="5716519167-11">(</span><span class="p" data-group-id="5716519167-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="5716519167-12">}</span><span class="p" data-group-id="5716519167-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="5716519167-13">(</span><span class="n">Y</span><span class="p" data-group-id="5716519167-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="5716519167-14">(</span><span class="p" data-group-id="5716519167-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5716519167-15">}</span><span class="p" data-group-id="5716519167-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="2999920143-16">(</span><span class="n">Msg</span><span class="p" data-group-id="2999920143-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2999920143-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2999920143-18">(</span><span class="p" data-group-id="2999920143-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2999920143-17">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="5716519167-16">(</span><span class="n">Msg</span><span class="p" data-group-id="5716519167-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5716519167-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5716519167-18">(</span><span class="p" data-group-id="5716519167-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5716519167-17">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="2999920143-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="2999920143-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="5716519167-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="5716519167-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="2999920143-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="2999920143-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="2999920143-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2999920143-22">(</span><span class="p" data-group-id="2999920143-22">)</span><span class="p" data-group-id="2999920143-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="2999920143-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2999920143-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="2999920143-24">(</span><span class="p" data-group-id="2999920143-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="2999920143-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2999920143-26">[</span><span class="p" data-group-id="2999920143-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2999920143-27">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="2999920143-26">]</span><span class="p" data-group-id="2999920143-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="2999920143-28">(</span><span class="n">Port</span><span class="p" data-group-id="2999920143-28">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="5716519167-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="5716519167-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="5716519167-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5716519167-22">(</span><span class="p" data-group-id="5716519167-22">)</span><span class="p" data-group-id="5716519167-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="5716519167-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5716519167-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="5716519167-24">(</span><span class="p" data-group-id="5716519167-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="5716519167-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5716519167-26">[</span><span class="p" data-group-id="5716519167-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="5716519167-27">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="5716519167-26">]</span><span class="p" data-group-id="5716519167-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="5716519167-28">(</span><span class="n">Port</span><span class="p" data-group-id="5716519167-28">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="2999920143-29">(</span><span class="n">Port</span><span class="p" data-group-id="2999920143-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="5716519167-29">(</span><span class="n">Port</span><span class="p" data-group-id="5716519167-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="2999920143-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2999920143-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2999920143-31">{</span><span class="nf">self</span><span class="p" data-group-id="2999920143-32">(</span><span class="p" data-group-id="2999920143-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2999920143-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="2999920143-34">(</span><span class="n">Msg</span><span class="p" data-group-id="2999920143-34">)</span><span class="p" data-group-id="2999920143-33">}</span><span class="p" data-group-id="2999920143-31">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="5716519167-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5716519167-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5716519167-31">{</span><span class="nf">self</span><span class="p" data-group-id="5716519167-32">(</span><span class="p" data-group-id="5716519167-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5716519167-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="5716519167-34">(</span><span class="n">Msg</span><span class="p" data-group-id="5716519167-34">)</span><span class="p" data-group-id="5716519167-33">}</span><span class="p" data-group-id="5716519167-31">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="2999920143-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2999920143-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2999920143-36">}</span><span class="p" data-group-id="2999920143-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2999920143-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="2999920143-38">(</span><span class="n">Data</span><span class="p" data-group-id="2999920143-38">)</span><span class="p" data-group-id="2999920143-37">}</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="5716519167-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5716519167-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5716519167-36">}</span><span class="p" data-group-id="5716519167-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5716519167-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="5716519167-38">(</span><span class="n">Data</span><span class="p" data-group-id="5716519167-38">)</span><span class="p" data-group-id="5716519167-37">}</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="2999920143-39">(</span><span class="n">Port</span><span class="p" data-group-id="2999920143-39">)</span><span class="p">;</span><span class="w">
│ │ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="5716519167-39">(</span><span class="n">Port</span><span class="p" data-group-id="5716519167-39">)</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2999920143-40">{</span><span class="nf">self</span><span class="p" data-group-id="2999920143-41">(</span><span class="p" data-group-id="2999920143-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="2999920143-40">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5716519167-40">{</span><span class="nf">self</span><span class="p" data-group-id="5716519167-41">(</span><span class="p" data-group-id="5716519167-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="5716519167-40">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="2999920143-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="2999920143-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="2999920143-43">(</span><span class="ss">normal</span><span class="p" data-group-id="2999920143-43">)</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="5716519167-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="5716519167-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="5716519167-43">(</span><span class="ss">normal</span><span class="p" data-group-id="5716519167-43">)</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="2999920143-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2999920143-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="2999920143-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="2999920143-45">)</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="5716519167-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="5716519167-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="5716519167-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="5716519167-45">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Notice that calling <code class="inline">complex2:foo/1</code> and <code class="inline">complex2:bar/1</code> results in the tuple
│ │ │ │  <code class="inline">{foo,X}</code> or <code class="inline">{bar,Y}</code> being sent to the <code class="inline">complex</code> process, which codes them as
│ │ │ │  binaries and sends them to the port. This means that the C program must be able
│ │ │ │  to handle these two tuples.</p><h2 id="c-program" class="section-heading">
│ │ │ │    <a href="#c-program" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │ @@ -267,24 +267,24 @@
│ │ │ │      -L/usr/local/otp/lib/erl_interface-3.9.2/lib \
│ │ │ │      complex.c erl_comm.c ei.c -lei -lpthread</code></pre><p>In Erlang/OTP R5B and later versions of OTP, the <code class="inline">include</code> and <code class="inline">lib</code> directories
│ │ │ │  are situated under <code class="inline">$OTPROOT/lib/erl_interface-VSN</code>, where <code class="inline">$OTPROOT</code> is the
│ │ │ │  root directory of the OTP installation (<code class="inline">/usr/local/otp</code> in the recent example)
│ │ │ │  and <code class="inline">VSN</code> is the version of the Erl_interface application (3.2.1 in the recent
│ │ │ │  example).</p><p>In R4B and earlier versions of OTP, <code class="inline">include</code> and <code class="inline">lib</code> are situated under
│ │ │ │  <code class="inline">$OTPROOT/usr</code>.</p><p><em>Step 2.</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="sc">$ </span><span class="ss">erl</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="3049131981-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="3049131981-1">]</span><span class="w"> </span><span class="p" data-group-id="3049131981-2">[</span><span class="ss">source</span><span class="p" data-group-id="3049131981-2">]</span><span class="w"> </span><span class="p" data-group-id="3049131981-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="3049131981-3">]</span><span class="w"> </span><span class="p" data-group-id="3049131981-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3049131981-4">]</span><span class="w"> </span><span class="p" data-group-id="3049131981-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="3049131981-5">]</span><span class="w"> </span><span class="p" data-group-id="3049131981-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3049131981-6">]</span><span class="w"> </span><span class="p" data-group-id="3049131981-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="3049131981-7">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="0535814726-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="0535814726-1">]</span><span class="w"> </span><span class="p" data-group-id="0535814726-2">[</span><span class="ss">source</span><span class="p" data-group-id="0535814726-2">]</span><span class="w"> </span><span class="p" data-group-id="0535814726-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="0535814726-3">]</span><span class="w"> </span><span class="p" data-group-id="0535814726-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0535814726-4">]</span><span class="w"> </span><span class="p" data-group-id="0535814726-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="0535814726-5">]</span><span class="w"> </span><span class="p" data-group-id="0535814726-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="0535814726-6">]</span><span class="w"> </span><span class="p" data-group-id="0535814726-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="0535814726-7">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="3049131981-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="3049131981-9">(</span><span class="p" data-group-id="3049131981-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="3049131981-8">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="3049131981-10">(</span><span class="ss">complex2</span><span class="p" data-group-id="3049131981-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3049131981-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex2</span><span class="p" data-group-id="3049131981-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2276243805-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="2276243805-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="0535814726-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="0535814726-9">(</span><span class="p" data-group-id="0535814726-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="0535814726-8">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="0535814726-10">(</span><span class="ss">complex2</span><span class="p" data-group-id="0535814726-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0535814726-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex2</span><span class="p" data-group-id="0535814726-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5607646263-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="5607646263-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.34</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="2276243805-2">(</span><span class="mi">3</span><span class="p" data-group-id="2276243805-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="5607646263-2">(</span><span class="mi">3</span><span class="p" data-group-id="5607646263-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="2276243805-3">(</span><span class="mi">5</span><span class="p" data-group-id="2276243805-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="5607646263-3">(</span><span class="mi">5</span><span class="p" data-group-id="5607646263-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="2276243805-4">(</span><span class="mi">352</span><span class="p" data-group-id="2276243805-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="5607646263-4">(</span><span class="mi">352</span><span class="p" data-group-id="5607646263-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">704</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="2276243805-5">(</span><span class="p" data-group-id="2276243805-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="5607646263-5">(</span><span class="p" data-group-id="5607646263-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">stop</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/eff_guide_processes.xhtml
│ │ │ │ @@ -24,45 +24,45 @@
│ │ │ │    <a href="#creating-an-erlang-process" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Creating an Erlang Process</span>
│ │ │ │  </h2>
│ │ │ │  <p>An Erlang process is lightweight compared to threads and processes in operating
│ │ │ │  systems.</p><p>A newly spawned Erlang process uses 327 words of memory. The size can be found
│ │ │ │ -as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="5016915400-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p">.</span><span class="mi">3</span><span class="p" data-group-id="5016915400-1">]</span><span class="w"> </span><span class="p" data-group-id="5016915400-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="5016915400-2">]</span><span class="w"> </span><span class="p" data-group-id="5016915400-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="5016915400-3">]</span><span class="w"> </span><span class="p" data-group-id="5016915400-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="5016915400-4">]</span><span class="w"> </span><span class="p" data-group-id="5016915400-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="5016915400-5">]</span><span class="w"> </span><span class="p" data-group-id="5016915400-6">[</span><span class="ss">jit</span><span class="p" data-group-id="5016915400-6">]</span><span class="w">
│ │ │ │ +as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="6115256480-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p">.</span><span class="mi">3</span><span class="p" data-group-id="6115256480-1">]</span><span class="w"> </span><span class="p" data-group-id="6115256480-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="6115256480-2">]</span><span class="w"> </span><span class="p" data-group-id="6115256480-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="6115256480-3">]</span><span class="w"> </span><span class="p" data-group-id="6115256480-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="6115256480-4">]</span><span class="w"> </span><span class="p" data-group-id="6115256480-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="6115256480-5">]</span><span class="w"> </span><span class="p" data-group-id="6115256480-6">[</span><span class="ss">jit</span><span class="p" data-group-id="6115256480-6">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mf">2.3</span><span class="w"> </span><span class="p" data-group-id="5016915400-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="5016915400-8">(</span><span class="p" data-group-id="5016915400-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="5016915400-7">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="5016915400-9">(</span><span class="p" data-group-id="5016915400-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="ss">infinity</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mf">2.3</span><span class="w"> </span><span class="p" data-group-id="6115256480-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="6115256480-8">(</span><span class="p" data-group-id="6115256480-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="6115256480-7">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="6115256480-9">(</span><span class="p" data-group-id="6115256480-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="ss">infinity</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">43.39164016</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="5016915400-10">{</span><span class="p">_</span><span class="p">,</span><span class="n">Bytes</span><span class="p" data-group-id="5016915400-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">process_info</span><span class="p" data-group-id="5016915400-11">(</span><span class="nf">spawn</span><span class="p" data-group-id="5016915400-12">(</span><span class="n">Fun</span><span class="p" data-group-id="5016915400-12">)</span><span class="p">,</span><span class="w"> </span><span class="nb">memory</span><span class="p" data-group-id="5016915400-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5016915400-13">{</span><span class="nb">memory</span><span class="p">,</span><span class="mi">2616</span><span class="p" data-group-id="5016915400-13">}</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="n">Bytes</span><span class="w"> </span><span class="ow">div</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="5016915400-14">(</span><span class="ss">wordsize</span><span class="p" data-group-id="5016915400-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="6115256480-10">{</span><span class="p">_</span><span class="p">,</span><span class="n">Bytes</span><span class="p" data-group-id="6115256480-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">process_info</span><span class="p" data-group-id="6115256480-11">(</span><span class="nf">spawn</span><span class="p" data-group-id="6115256480-12">(</span><span class="n">Fun</span><span class="p" data-group-id="6115256480-12">)</span><span class="p">,</span><span class="w"> </span><span class="nb">memory</span><span class="p" data-group-id="6115256480-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6115256480-13">{</span><span class="nb">memory</span><span class="p">,</span><span class="mi">2616</span><span class="p" data-group-id="6115256480-13">}</span><span class="gp unselectable">
│ │ │ │ +3&gt; </span><span class="n">Bytes</span><span class="w"> </span><span class="ow">div</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="6115256480-14">(</span><span class="ss">wordsize</span><span class="p" data-group-id="6115256480-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">327</span></code></pre><p>The size includes 233 words for the heap area (which includes the stack). The
│ │ │ │  garbage collector increases the heap as needed.</p><p>The main (outer) loop for a process <em>must</em> be tail-recursive. Otherwise, the
│ │ │ │ -stack grows until the process terminates.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="4059511893-1">(</span><span class="p" data-group-id="4059511893-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +stack grows until the process terminates.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="5136368421-1">(</span><span class="p" data-group-id="5136368421-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │    </span><span class="k">receive</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="4059511893-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4059511893-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="4059511893-3">(</span><span class="n">Msg</span><span class="p" data-group-id="4059511893-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="nf">loop</span><span class="p" data-group-id="4059511893-4">(</span><span class="p" data-group-id="4059511893-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="4059511893-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4059511893-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -          </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="4059511893-6">(</span><span class="n">Msg</span><span class="p" data-group-id="4059511893-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="5136368421-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5136368421-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="5136368421-3">(</span><span class="n">Msg</span><span class="p" data-group-id="5136368421-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="nf">loop</span><span class="p" data-group-id="5136368421-4">(</span><span class="p" data-group-id="5136368421-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="5136368421-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5136368421-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +          </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5136368421-6">(</span><span class="n">Msg</span><span class="p" data-group-id="5136368421-6">)</span><span class="p">,</span><span class="w">
│ │ │ │            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Reply</span><span class="p">,</span><span class="w">
│ │ │ │ -          </span><span class="nf">loop</span><span class="p" data-group-id="4059511893-7">(</span><span class="p" data-group-id="4059511893-7">)</span><span class="w">
│ │ │ │ +          </span><span class="nf">loop</span><span class="p" data-group-id="5136368421-7">(</span><span class="p" data-group-id="5136368421-7">)</span><span class="w">
│ │ │ │    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4059511893-8">(</span><span class="s">&quot;Message is processed</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4059511893-9">[</span><span class="p" data-group-id="4059511893-9">]</span><span class="p" data-group-id="4059511893-8">)</span><span class="p">.</span></code></pre><p>The call to <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> will never be executed, but a return address will
│ │ │ │ +  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5136368421-8">(</span><span class="s">&quot;Message is processed</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5136368421-9">[</span><span class="p" data-group-id="5136368421-9">]</span><span class="p" data-group-id="5136368421-8">)</span><span class="p">.</span></code></pre><p>The call to <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> will never be executed, but a return address will
│ │ │ │  still be pushed to the stack each time <code class="inline">loop/0</code> is called recursively. The
│ │ │ │ -correct tail-recursive version of the function looks as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="7663265901-1">(</span><span class="p" data-group-id="7663265901-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +correct tail-recursive version of the function looks as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="4608905190-1">(</span><span class="p" data-group-id="4608905190-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │     </span><span class="k">receive</span><span class="w">
│ │ │ │ -      </span><span class="p" data-group-id="7663265901-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7663265901-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="7663265901-3">(</span><span class="n">Msg</span><span class="p" data-group-id="7663265901-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="nf">loop</span><span class="p" data-group-id="7663265901-4">(</span><span class="p" data-group-id="7663265901-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ -      </span><span class="p" data-group-id="7663265901-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7663265901-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -         </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="7663265901-6">(</span><span class="n">Msg</span><span class="p" data-group-id="7663265901-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +      </span><span class="p" data-group-id="4608905190-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4608905190-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="4608905190-3">(</span><span class="n">Msg</span><span class="p" data-group-id="4608905190-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +         </span><span class="nf">loop</span><span class="p" data-group-id="4608905190-4">(</span><span class="p" data-group-id="4608905190-4">)</span><span class="p">;</span><span class="w">
│ │ │ │ +      </span><span class="p" data-group-id="4608905190-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4608905190-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +         </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="4608905190-6">(</span><span class="n">Msg</span><span class="p" data-group-id="4608905190-6">)</span><span class="p">,</span><span class="w">
│ │ │ │           </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Reply</span><span class="p">,</span><span class="w">
│ │ │ │ -         </span><span class="nf">loop</span><span class="p" data-group-id="7663265901-7">(</span><span class="p" data-group-id="7663265901-7">)</span><span class="w">
│ │ │ │ +         </span><span class="nf">loop</span><span class="p" data-group-id="4608905190-7">(</span><span class="p" data-group-id="4608905190-7">)</span><span class="w">
│ │ │ │   </span><span class="k">end</span><span class="p">.</span></code></pre><h3 id="initial-heap-size" class="section-heading">
│ │ │ │    <a href="#initial-heap-size" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Initial Heap Size</span>
│ │ │ │  </h3>
│ │ │ │  <p>The default initial heap size of 233 words is quite conservative to support
│ │ │ │ @@ -94,30 +94,30 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Receiving messages</span>
│ │ │ │  </h2>
│ │ │ │  <p>The cost of receiving messages depends on how complicated the <code class="inline">receive</code>
│ │ │ │  expression is. A simple expression that matches any message is very cheap
│ │ │ │  because it retrieves the first message in the message queue:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="1579728146-1">(</span><span class="n">Message</span><span class="p" data-group-id="1579728146-1">)</span><span class="w">
│ │ │ │ +    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="6580666043-1">(</span><span class="n">Message</span><span class="p" data-group-id="6580666043-1">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>However, this is not always convenient: we can receive a message that we do not
│ │ │ │  know how to handle at this point, so it is common to only match the messages we
│ │ │ │  expect:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4280251970-1">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4280251970-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="4280251970-2">(</span><span class="n">Message</span><span class="p" data-group-id="4280251970-2">)</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4407092623-1">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4407092623-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="4407092623-2">(</span><span class="n">Message</span><span class="p" data-group-id="4407092623-2">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>While this is convenient it means that the entire message queue must be searched
│ │ │ │  until it finds a matching message. This is very expensive for processes with
│ │ │ │  long message queues, so there is an optimization for the common case of
│ │ │ │ -sending a request and waiting for a response shortly after:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="3776933115-1">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="3776933115-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3776933115-2">{</span><span class="nf">self</span><span class="p" data-group-id="3776933115-3">(</span><span class="p" data-group-id="3776933115-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="3776933115-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +sending a request and waiting for a response shortly after:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="4001366232-1">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="4001366232-1">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4001366232-2">{</span><span class="nf">self</span><span class="p" data-group-id="4001366232-3">(</span><span class="p" data-group-id="4001366232-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="4001366232-2">}</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3776933115-4">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="3776933115-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="3776933115-5">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3776933115-6">[</span><span class="ss">flush</span><span class="p" data-group-id="3776933115-6">]</span><span class="p" data-group-id="3776933115-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="nf">handle_reply</span><span class="p" data-group-id="3776933115-7">(</span><span class="n">Reply</span><span class="p" data-group-id="3776933115-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3776933115-8">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="3776933115-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nf">handle_error</span><span class="p" data-group-id="3776933115-9">(</span><span class="n">Reason</span><span class="p" data-group-id="3776933115-9">)</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4001366232-4">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="4001366232-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="4001366232-5">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4001366232-6">[</span><span class="ss">flush</span><span class="p" data-group-id="4001366232-6">]</span><span class="p" data-group-id="4001366232-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="nf">handle_reply</span><span class="p" data-group-id="4001366232-7">(</span><span class="n">Reply</span><span class="p" data-group-id="4001366232-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="4001366232-8">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="4001366232-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nf">handle_error</span><span class="p" data-group-id="4001366232-9">(</span><span class="n">Reason</span><span class="p" data-group-id="4001366232-9">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>Since the compiler knows that the reference created by
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#monitor/2"><code class="inline">monitor/2</code></a> cannot exist before the call (since it is a globally
│ │ │ │  unique identifier), and that the <code class="inline">receive</code> only matches messages that contain
│ │ │ │  said reference, it will tell the emulator to search only the messages that
│ │ │ │  arrived after the call to <a href="../../../lib/../erts/doc/html/erlang.html#monitor/2"><code class="inline">monitor/2</code></a>.</p><p>The above is a simple example where one is but guaranteed that the optimization
│ │ │ │  will take, but what about more complicated code?</p><p><a href="" id="recv_opt_info"></a></p><h3 id="option-recv_opt_info" class="section-heading">
│ │ │ │    <a href="#option-recv_opt_info" class="hover-link">
│ │ │ │ @@ -133,101 +133,101 @@
│ │ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">200</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">NOT</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">clauses</span><span class="w"> </span><span class="ss">do</span><span class="w"> </span><span class="ow">not</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="ss">suitable</span><span class="w"> </span><span class="ss">reference</span><span class="w">
│ │ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">206</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">used</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">mark</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="ss">message</span><span class="w"> </span><span class="ss">queue</span><span class="w"> </span><span class="ss">position</span><span class="w">
│ │ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">208</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">clauses</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">created</span><span class="w"> </span><span class="ss">by</span><span class="w"> </span><span class="nb">monitor</span><span class="p">/</span><span class="mi">2</span><span class="w"> </span><span class="ss">at</span><span class="w"> </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">206</span><span class="w">
│ │ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">219</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">INFO</span><span class="p">:</span><span class="w"> </span><span class="ss">passing</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">created</span><span class="w"> </span><span class="ss">by</span><span class="w"> </span><span class="ss">make_ref</span><span class="p">/</span><span class="mi">0</span><span class="w"> </span><span class="ss">at</span><span class="w"> </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">218</span><span class="w">
│ │ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">222</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">clauses</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">function</span><span class="w"> </span><span class="ss">parameter</span><span class="w"> </span><span class="mi">1</span></code></pre><p>To make it clearer exactly what code the warnings refer to, the warnings in the
│ │ │ │  following examples are inserted as comments after the clause they refer to, for
│ │ │ │  example:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% DO</span><span class="w">
│ │ │ │ -</span><span class="nf">simple_receive</span><span class="p" data-group-id="1585262118-1">(</span><span class="p" data-group-id="1585262118-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">simple_receive</span><span class="p" data-group-id="5716909259-1">(</span><span class="p" data-group-id="5716909259-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="c1">%% efficiency_guide.erl:194: Warning: INFO: not a selective receive, this is always fast</span><span class="w">
│ │ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="1585262118-2">(</span><span class="n">Message</span><span class="p" data-group-id="1585262118-2">)</span><span class="w">
│ │ │ │ +    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5716909259-2">(</span><span class="n">Message</span><span class="p" data-group-id="5716909259-2">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% DO NOT, unless Tag is known to be a suitable reference: see</span><span class="w">
│ │ │ │  </span><span class="c1">%% cross_function_receive/0 further down.</span><span class="w">
│ │ │ │ -</span><span class="nf">selective_receive</span><span class="p" data-group-id="1585262118-3">(</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="1585262118-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">selective_receive</span><span class="p" data-group-id="5716909259-3">(</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5716909259-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="c1">%% efficiency_guide.erl:200: Warning: NOT OPTIMIZED: all clauses do not match a suitable reference</span><span class="w">
│ │ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1585262118-4">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="1585262118-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="1585262118-5">(</span><span class="n">Message</span><span class="p" data-group-id="1585262118-5">)</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5716909259-4">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5716909259-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5716909259-5">(</span><span class="n">Message</span><span class="p" data-group-id="5716909259-5">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% DO</span><span class="w">
│ │ │ │ -</span><span class="nf">optimized_receive</span><span class="p" data-group-id="1585262118-6">(</span><span class="n">Process</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="1585262118-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">optimized_receive</span><span class="p" data-group-id="5716909259-6">(</span><span class="n">Process</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="5716909259-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  </span><span class="c1">%% efficiency_guide.erl:206: Warning: OPTIMIZED: reference used to mark a message queue position</span><span class="w">
│ │ │ │ -    </span><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="1585262118-7">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="1585262118-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1585262118-8">{</span><span class="nf">self</span><span class="p" data-group-id="1585262118-9">(</span><span class="p" data-group-id="1585262118-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="1585262118-8">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="5716909259-7">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="5716909259-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5716909259-8">{</span><span class="nf">self</span><span class="p" data-group-id="5716909259-9">(</span><span class="p" data-group-id="5716909259-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="5716909259-8">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="c1">%% efficiency_guide.erl:208: Warning: OPTIMIZED: matches reference created by monitor/2 at efficiency_guide.erl:206</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1585262118-10">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="1585262118-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="1585262118-11">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1585262118-12">[</span><span class="ss">flush</span><span class="p" data-group-id="1585262118-12">]</span><span class="p" data-group-id="1585262118-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="nf">handle_reply</span><span class="p" data-group-id="1585262118-13">(</span><span class="n">Reply</span><span class="p" data-group-id="1585262118-13">)</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1585262118-14">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="1585262118-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">handle_error</span><span class="p" data-group-id="1585262118-15">(</span><span class="n">Reason</span><span class="p" data-group-id="1585262118-15">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5716909259-10">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="5716909259-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="5716909259-11">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5716909259-12">[</span><span class="ss">flush</span><span class="p" data-group-id="5716909259-12">]</span><span class="p" data-group-id="5716909259-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="nf">handle_reply</span><span class="p" data-group-id="5716909259-13">(</span><span class="n">Reply</span><span class="p" data-group-id="5716909259-13">)</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5716909259-14">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="5716909259-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">handle_error</span><span class="p" data-group-id="5716909259-15">(</span><span class="n">Reason</span><span class="p" data-group-id="5716909259-15">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% DO</span><span class="w">
│ │ │ │ -</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="1585262118-16">(</span><span class="p" data-group-id="1585262118-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="5716909259-16">(</span><span class="p" data-group-id="5716909259-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% efficiency_guide.erl:218: Warning: OPTIMIZED: reference used to mark a message queue position</span><span class="w">
│ │ │ │ -    </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="1585262118-17">(</span><span class="p" data-group-id="1585262118-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="5716909259-17">(</span><span class="p" data-group-id="5716909259-17">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="c1">%% efficiency_guide.erl:219: Warning: INFO: passing reference created by make_ref/0 at efficiency_guide.erl:218</span><span class="w">
│ │ │ │ -    </span><span class="nf">cross_function_receive</span><span class="p" data-group-id="1585262118-18">(</span><span class="n">Ref</span><span class="p" data-group-id="1585262118-18">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">cross_function_receive</span><span class="p" data-group-id="5716909259-18">(</span><span class="n">Ref</span><span class="p" data-group-id="5716909259-18">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="1585262118-19">(</span><span class="n">Ref</span><span class="p" data-group-id="1585262118-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="5716909259-19">(</span><span class="n">Ref</span><span class="p" data-group-id="5716909259-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% efficiency_guide.erl:222: Warning: OPTIMIZED: all clauses match reference in function parameter 1</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="1585262118-20">{</span><span class="n">Ref</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="1585262118-20">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="1585262118-21">(</span><span class="n">Message</span><span class="p" data-group-id="1585262118-21">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5716909259-20">{</span><span class="n">Ref</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5716909259-20">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5716909259-21">(</span><span class="n">Message</span><span class="p" data-group-id="5716909259-21">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><h2 id="literal-pool" class="section-heading">
│ │ │ │    <a href="#literal-pool" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Literal Pool</span>
│ │ │ │  </h2>
│ │ │ │  <p>Constant Erlang terms (hereafter called <em>literals</em>) are kept in <em>literal pools</em>;
│ │ │ │  each loaded module has its own pool. The following function does not build the
│ │ │ │  tuple every time it is called (only to have it discarded the next time the
│ │ │ │  garbage collector was run), but the tuple is located in the module's literal
│ │ │ │ -pool:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">days_in_month</span><span class="p" data-group-id="6829212764-1">(</span><span class="n">M</span><span class="p" data-group-id="6829212764-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">element</span><span class="p" data-group-id="6829212764-2">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6829212764-3">{</span><span class="mi">31</span><span class="p">,</span><span class="mi">28</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p" data-group-id="6829212764-3">}</span><span class="p" data-group-id="6829212764-2">)</span><span class="p">.</span></code></pre><p>If a literal, or a term that contains a literal, is inserted into an Ets table,
│ │ │ │ +pool:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">days_in_month</span><span class="p" data-group-id="9624781908-1">(</span><span class="n">M</span><span class="p" data-group-id="9624781908-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">element</span><span class="p" data-group-id="9624781908-2">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9624781908-3">{</span><span class="mi">31</span><span class="p">,</span><span class="mi">28</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p" data-group-id="9624781908-3">}</span><span class="p" data-group-id="9624781908-2">)</span><span class="p">.</span></code></pre><p>If a literal, or a term that contains a literal, is inserted into an Ets table,
│ │ │ │  it is <em>copied</em>. The reason is that the module containing the literal can be
│ │ │ │  unloaded in the future.</p><p>When a literal is sent to another process, it is <em>not</em> copied. When a module
│ │ │ │  holding a literal is unloaded, the literal will be copied to the heap of all
│ │ │ │  processes that hold references to that literal.</p><p>There also exists a global literal pool that is managed by the
│ │ │ │  <a href="../../../lib/../erts/doc/html/persistent_term.html"><code class="inline">persistent_term</code></a> module.</p><p>By default, 1 GB of virtual address space is reserved for all literal pools (in
│ │ │ │  BEAM code and persistent terms). The amount of virtual address space reserved
│ │ │ │  for literals can be changed by using the
│ │ │ │  <a href="../../../lib/../erts/doc/html/erts_alloc.xhtml#MIscs"><code class="inline">+MIscs option</code></a> when starting the emulator.</p><p>Here is an example how the reserved virtual address space for literals can be
│ │ │ │  raised to 2 GB (2048 MB):</p><pre><code class="text">erl +MIscs 2048</code></pre><h2 id="loss-of-sharing" class="section-heading">
│ │ │ │    <a href="#loss-of-sharing" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Loss of Sharing</span>
│ │ │ │  </h2>
│ │ │ │ -<p>An Erlang term can have shared subterms. Here is a simple example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7242545932-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="7242545932-1">}</span></code></pre><p>Shared subterms are <em>not</em> preserved in the following cases:</p><ul><li>When a term is sent to another process</li><li>When a term is passed as the initial process arguments in the <code class="inline">spawn</code> call</li><li>When a term is stored in an Ets table</li></ul><p>That is an optimization. Most applications do not send messages with shared
│ │ │ │ -subterms.</p><p>The following example shows how a shared subterm can be created:</p><pre><code class="makeup erlang" translate="no"><span class="nf">kilo_byte</span><span class="p" data-group-id="6519486148-1">(</span><span class="p" data-group-id="6519486148-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="6519486148-2">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6519486148-3">[</span><span class="mi">42</span><span class="p" data-group-id="6519486148-3">]</span><span class="p" data-group-id="6519486148-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>An Erlang term can have shared subterms. Here is a simple example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7334743775-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="7334743775-1">}</span></code></pre><p>Shared subterms are <em>not</em> preserved in the following cases:</p><ul><li>When a term is sent to another process</li><li>When a term is passed as the initial process arguments in the <code class="inline">spawn</code> call</li><li>When a term is stored in an Ets table</li></ul><p>That is an optimization. Most applications do not send messages with shared
│ │ │ │ +subterms.</p><p>The following example shows how a shared subterm can be created:</p><pre><code class="makeup erlang" translate="no"><span class="nf">kilo_byte</span><span class="p" data-group-id="6151293377-1">(</span><span class="p" data-group-id="6151293377-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="6151293377-2">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6151293377-3">[</span><span class="mi">42</span><span class="p" data-group-id="6151293377-3">]</span><span class="p" data-group-id="6151293377-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">kilo_byte</span><span class="p" data-group-id="6519486148-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6519486148-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">kilo_byte</span><span class="p" data-group-id="6151293377-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6151293377-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Acc</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">kilo_byte</span><span class="p" data-group-id="6519486148-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6519486148-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="6519486148-6">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6519486148-7">[</span><span class="n">Acc</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="6519486148-7">]</span><span class="p" data-group-id="6519486148-6">)</span><span class="p">.</span></code></pre><p><code class="inline">kilo_byte/1</code> creates a deep list. If <a href="../../../lib/../erts/doc/html/erlang.html#list_to_binary/1"><code class="inline">list_to_binary/1</code></a>
│ │ │ │ +</span><span class="nf">kilo_byte</span><span class="p" data-group-id="6151293377-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6151293377-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="6151293377-6">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6151293377-7">[</span><span class="n">Acc</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="6151293377-7">]</span><span class="p" data-group-id="6151293377-6">)</span><span class="p">.</span></code></pre><p><code class="inline">kilo_byte/1</code> creates a deep list. If <a href="../../../lib/../erts/doc/html/erlang.html#list_to_binary/1"><code class="inline">list_to_binary/1</code></a>
│ │ │ │  is called, the deep list can be converted to a binary of 1024 bytes:</p><pre><code class="text">1&gt; byte_size(list_to_binary(efficiency_guide:kilo_byte())).
│ │ │ │  1024</code></pre><p>Using the <code class="inline">erts_debug:size/1</code> BIF, it can be seen that the deep list only
│ │ │ │ -requires 22 words of heap space:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="2593166021-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="2593166021-2">(</span><span class="p" data-group-id="2593166021-2">)</span><span class="p" data-group-id="2593166021-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +requires 22 words of heap space:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="8703440317-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="8703440317-2">(</span><span class="p" data-group-id="8703440317-2">)</span><span class="p" data-group-id="8703440317-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">22</span></code></pre><p>Using the <code class="inline">erts_debug:flat_size/1</code> BIF, the size of the deep list can be
│ │ │ │  calculated if sharing is ignored. It becomes the size of the list when it has
│ │ │ │ -been sent to another process or stored in an Ets table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="9317962283-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="9317962283-2">(</span><span class="p" data-group-id="9317962283-2">)</span><span class="p" data-group-id="9317962283-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +been sent to another process or stored in an Ets table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="3851840335-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="3851840335-2">(</span><span class="p" data-group-id="3851840335-2">)</span><span class="p" data-group-id="3851840335-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4094</span></code></pre><p>It can be verified that sharing will be lost if the data is inserted into an Ets
│ │ │ │ -table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="1506035923-1">(</span><span class="ss">tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1506035923-2">[</span><span class="p" data-group-id="1506035923-2">]</span><span class="p" data-group-id="1506035923-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="7736300348-1">(</span><span class="ss">tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7736300348-2">[</span><span class="p" data-group-id="7736300348-2">]</span><span class="p" data-group-id="7736300348-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Ref</span><span class="o">&lt;</span><span class="mf">0.1662103692</span><span class="p">.</span><span class="mf">2407923716.214181</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">ets</span><span class="p">:</span><span class="nf">insert</span><span class="p" data-group-id="1506035923-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1506035923-4">{</span><span class="ss">key</span><span class="p">,</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="1506035923-5">(</span><span class="p" data-group-id="1506035923-5">)</span><span class="p" data-group-id="1506035923-4">}</span><span class="p" data-group-id="1506035923-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">ets</span><span class="p">:</span><span class="nf">insert</span><span class="p" data-group-id="7736300348-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7736300348-4">{</span><span class="ss">key</span><span class="p">,</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="7736300348-5">(</span><span class="p" data-group-id="7736300348-5">)</span><span class="p" data-group-id="7736300348-4">}</span><span class="p" data-group-id="7736300348-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="1506035923-6">(</span><span class="nf">element</span><span class="p" data-group-id="1506035923-7">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="1506035923-8">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="1506035923-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="1506035923-9">)</span><span class="p" data-group-id="1506035923-8">)</span><span class="p" data-group-id="1506035923-7">)</span><span class="p" data-group-id="1506035923-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="7736300348-6">(</span><span class="nf">element</span><span class="p" data-group-id="7736300348-7">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="7736300348-8">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="7736300348-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="7736300348-9">)</span><span class="p" data-group-id="7736300348-8">)</span><span class="p" data-group-id="7736300348-7">)</span><span class="p" data-group-id="7736300348-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4094</span><span class="gp unselectable">
│ │ │ │ -7&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="1506035923-10">(</span><span class="nf">element</span><span class="p" data-group-id="1506035923-11">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="1506035923-12">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="1506035923-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="1506035923-13">)</span><span class="p" data-group-id="1506035923-12">)</span><span class="p" data-group-id="1506035923-11">)</span><span class="p" data-group-id="1506035923-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +7&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="7736300348-10">(</span><span class="nf">element</span><span class="p" data-group-id="7736300348-11">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="7736300348-12">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="7736300348-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="7736300348-13">)</span><span class="p" data-group-id="7736300348-12">)</span><span class="p" data-group-id="7736300348-11">)</span><span class="p" data-group-id="7736300348-10">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4094</span></code></pre><p>When the data has passed through an Ets table, <code class="inline">erts_debug:size/1</code> and
│ │ │ │  <code class="inline">erts_debug:flat_size/1</code> return the same value. Sharing has been lost.</p><p>It is possible to build an <em>experimental</em> variant of the runtime system that
│ │ │ │  will preserve sharing when copying terms by giving the
│ │ │ │  <code class="inline">--enable-sharing-preserving</code> option to the <code class="inline">configure</code> script.</p><h2 id="smp-run-time-system" class="section-heading">
│ │ │ │    <a href="#smp-run-time-system" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ ├── OEBPS/eff_guide_functions.xhtml
│ │ │ │ @@ -27,67 +27,67 @@
│ │ │ │    <span class="text">Pattern Matching</span>
│ │ │ │  </h2>
│ │ │ │  <p>Pattern matching in function head as well as in <code class="inline">case</code> and <code class="inline">receive</code> clauses are
│ │ │ │  optimized by the compiler. With a few exceptions, there is nothing to gain by
│ │ │ │  rearranging clauses.</p><p>One exception is pattern matching of binaries. The compiler does not rearrange
│ │ │ │  clauses that match binaries. Placing the clause that matches against the empty
│ │ │ │  binary <em>last</em> is usually slightly faster than placing it <em>first</em>.</p><p>The following is a rather unnatural example to show another exception where
│ │ │ │ -rearranging clauses is beneficial:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map1</span><span class="p" data-group-id="6684725061-1">(</span><span class="ss">one</span><span class="p" data-group-id="6684725061-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="6684725061-2">(</span><span class="ss">two</span><span class="p" data-group-id="6684725061-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="6684725061-3">(</span><span class="ss">three</span><span class="p" data-group-id="6684725061-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="6684725061-4">(</span><span class="n">Int</span><span class="p" data-group-id="6684725061-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6684725061-5">(</span><span class="n">Int</span><span class="p" data-group-id="6684725061-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="6684725061-6">(</span><span class="ss">four</span><span class="p" data-group-id="6684725061-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="6684725061-7">(</span><span class="ss">five</span><span class="p" data-group-id="6684725061-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="6684725061-8">(</span><span class="ss">six</span><span class="p" data-group-id="6684725061-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>The problem is the clause with the variable <code class="inline">Int</code>. As a variable can match
│ │ │ │ +rearranging clauses is beneficial:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map1</span><span class="p" data-group-id="5827729842-1">(</span><span class="ss">one</span><span class="p" data-group-id="5827729842-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5827729842-2">(</span><span class="ss">two</span><span class="p" data-group-id="5827729842-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5827729842-3">(</span><span class="ss">three</span><span class="p" data-group-id="5827729842-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5827729842-4">(</span><span class="n">Int</span><span class="p" data-group-id="5827729842-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="5827729842-5">(</span><span class="n">Int</span><span class="p" data-group-id="5827729842-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5827729842-6">(</span><span class="ss">four</span><span class="p" data-group-id="5827729842-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5827729842-7">(</span><span class="ss">five</span><span class="p" data-group-id="5827729842-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5827729842-8">(</span><span class="ss">six</span><span class="p" data-group-id="5827729842-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>The problem is the clause with the variable <code class="inline">Int</code>. As a variable can match
│ │ │ │  anything, including the atoms <code class="inline">four</code>, <code class="inline">five</code>, and <code class="inline">six</code>, which the following
│ │ │ │  clauses also match, the compiler must generate suboptimal code that executes as
│ │ │ │  follows:</p><ul><li>First, the input value is compared to <code class="inline">one</code>, <code class="inline">two</code>, and <code class="inline">three</code> (using a
│ │ │ │  single instruction that does a binary search; thus, quite efficient even if
│ │ │ │  there are many values) to select which one of the first three clauses to
│ │ │ │  execute (if any).</li><li>If none of the first three clauses match, the fourth clause match as a
│ │ │ │  variable always matches.</li><li>If the guard test <a href="../../../lib/../erts/doc/html/erlang.html#is_integer/1"><code class="inline">is_integer(Int)</code></a> succeeds, the fourth
│ │ │ │  clause is executed.</li><li>If the guard test fails, the input value is compared to <code class="inline">four</code>, <code class="inline">five</code>, and
│ │ │ │  <code class="inline">six</code>, and the appropriate clause is selected. (There is a <code class="inline">function_clause</code>
│ │ │ │ -exception if none of the values matched.)</li></ul><p>Rewriting to either:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map2</span><span class="p" data-group-id="2170216876-1">(</span><span class="ss">one</span><span class="p" data-group-id="2170216876-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="2170216876-2">(</span><span class="ss">two</span><span class="p" data-group-id="2170216876-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="2170216876-3">(</span><span class="ss">three</span><span class="p" data-group-id="2170216876-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="2170216876-4">(</span><span class="ss">four</span><span class="p" data-group-id="2170216876-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="2170216876-5">(</span><span class="ss">five</span><span class="p" data-group-id="2170216876-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="2170216876-6">(</span><span class="ss">six</span><span class="p" data-group-id="2170216876-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="2170216876-7">(</span><span class="n">Int</span><span class="p" data-group-id="2170216876-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="2170216876-8">(</span><span class="n">Int</span><span class="p" data-group-id="2170216876-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>or:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map3</span><span class="p" data-group-id="6563881498-1">(</span><span class="n">Int</span><span class="p" data-group-id="6563881498-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6563881498-2">(</span><span class="n">Int</span><span class="p" data-group-id="6563881498-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="6563881498-3">(</span><span class="ss">one</span><span class="p" data-group-id="6563881498-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="6563881498-4">(</span><span class="ss">two</span><span class="p" data-group-id="6563881498-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="6563881498-5">(</span><span class="ss">three</span><span class="p" data-group-id="6563881498-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="6563881498-6">(</span><span class="ss">four</span><span class="p" data-group-id="6563881498-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="6563881498-7">(</span><span class="ss">five</span><span class="p" data-group-id="6563881498-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="6563881498-8">(</span><span class="ss">six</span><span class="p" data-group-id="6563881498-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>gives slightly more efficient matching code.</p><p>Another example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs1</span><span class="p" data-group-id="5248819872-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5248819872-2">[</span><span class="p" data-group-id="5248819872-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="5248819872-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +exception if none of the values matched.)</li></ul><p>Rewriting to either:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map2</span><span class="p" data-group-id="6740851257-1">(</span><span class="ss">one</span><span class="p" data-group-id="6740851257-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="6740851257-2">(</span><span class="ss">two</span><span class="p" data-group-id="6740851257-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="6740851257-3">(</span><span class="ss">three</span><span class="p" data-group-id="6740851257-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="6740851257-4">(</span><span class="ss">four</span><span class="p" data-group-id="6740851257-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="6740851257-5">(</span><span class="ss">five</span><span class="p" data-group-id="6740851257-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="6740851257-6">(</span><span class="ss">six</span><span class="p" data-group-id="6740851257-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="6740851257-7">(</span><span class="n">Int</span><span class="p" data-group-id="6740851257-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6740851257-8">(</span><span class="n">Int</span><span class="p" data-group-id="6740851257-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>or:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map3</span><span class="p" data-group-id="6445294503-1">(</span><span class="n">Int</span><span class="p" data-group-id="6445294503-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6445294503-2">(</span><span class="n">Int</span><span class="p" data-group-id="6445294503-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="6445294503-3">(</span><span class="ss">one</span><span class="p" data-group-id="6445294503-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="6445294503-4">(</span><span class="ss">two</span><span class="p" data-group-id="6445294503-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="6445294503-5">(</span><span class="ss">three</span><span class="p" data-group-id="6445294503-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="6445294503-6">(</span><span class="ss">four</span><span class="p" data-group-id="6445294503-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="6445294503-7">(</span><span class="ss">five</span><span class="p" data-group-id="6445294503-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="6445294503-8">(</span><span class="ss">six</span><span class="p" data-group-id="6445294503-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>gives slightly more efficient matching code.</p><p>Another example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs1</span><span class="p" data-group-id="9464469035-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9464469035-2">[</span><span class="p" data-group-id="9464469035-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="9464469035-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Ys</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">map_pairs1</span><span class="p" data-group-id="5248819872-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5248819872-4">[</span><span class="p" data-group-id="5248819872-4">]</span><span class="p" data-group-id="5248819872-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">map_pairs1</span><span class="p" data-group-id="9464469035-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9464469035-4">[</span><span class="p" data-group-id="9464469035-4">]</span><span class="p" data-group-id="9464469035-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Xs</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">map_pairs1</span><span class="p" data-group-id="5248819872-5">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5248819872-6">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="5248819872-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5248819872-7">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="5248819872-7">]</span><span class="p" data-group-id="5248819872-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5248819872-8">[</span><span class="n">Map</span><span class="p" data-group-id="5248819872-9">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5248819872-9">)</span><span class="p">|</span><span class="nf">map_pairs1</span><span class="p" data-group-id="5248819872-10">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="5248819872-10">)</span><span class="p" data-group-id="5248819872-8">]</span><span class="p">.</span></code></pre><p>The first argument is <em>not</em> a problem. It is variable, but it is a variable in
│ │ │ │ +</span><span class="nf">map_pairs1</span><span class="p" data-group-id="9464469035-5">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9464469035-6">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="9464469035-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9464469035-7">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="9464469035-7">]</span><span class="p" data-group-id="9464469035-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9464469035-8">[</span><span class="n">Map</span><span class="p" data-group-id="9464469035-9">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9464469035-9">)</span><span class="p">|</span><span class="nf">map_pairs1</span><span class="p" data-group-id="9464469035-10">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="9464469035-10">)</span><span class="p" data-group-id="9464469035-8">]</span><span class="p">.</span></code></pre><p>The first argument is <em>not</em> a problem. It is variable, but it is a variable in
│ │ │ │  all clauses. The problem is the variable in the second argument, <code class="inline">Xs</code>, in the
│ │ │ │  middle clause. Because the variable can match anything, the compiler is not
│ │ │ │  allowed to rearrange the clauses, but must generate code that matches them in
│ │ │ │  the order written.</p><p>If the function is rewritten as follows, the compiler is free to rearrange the
│ │ │ │ -clauses:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs2</span><span class="p" data-group-id="9146765480-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9146765480-2">[</span><span class="p" data-group-id="9146765480-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="9146765480-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +clauses:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs2</span><span class="p" data-group-id="2587998674-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2587998674-2">[</span><span class="p" data-group-id="2587998674-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="2587998674-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Ys</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">map_pairs2</span><span class="p" data-group-id="9146765480-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9146765480-4">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="9146765480-4">]</span><span class="o">=</span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9146765480-5">[</span><span class="p" data-group-id="9146765480-5">]</span><span class="w"> </span><span class="p" data-group-id="9146765480-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">map_pairs2</span><span class="p" data-group-id="2587998674-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2587998674-4">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="2587998674-4">]</span><span class="o">=</span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2587998674-5">[</span><span class="p" data-group-id="2587998674-5">]</span><span class="w"> </span><span class="p" data-group-id="2587998674-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Xs</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">map_pairs2</span><span class="p" data-group-id="9146765480-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9146765480-7">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="9146765480-7">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9146765480-8">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="9146765480-8">]</span><span class="p" data-group-id="9146765480-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9146765480-9">[</span><span class="n">Map</span><span class="p" data-group-id="9146765480-10">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9146765480-10">)</span><span class="p">|</span><span class="nf">map_pairs2</span><span class="p" data-group-id="9146765480-11">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="9146765480-11">)</span><span class="p" data-group-id="9146765480-9">]</span><span class="p">.</span></code></pre><p>The compiler will generate code similar to this:</p><p><strong>DO NOT (already done by the compiler)</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="3996410128-1">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs0</span><span class="p">,</span><span class="w"> </span><span class="n">Ys0</span><span class="p" data-group-id="3996410128-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">map_pairs2</span><span class="p" data-group-id="2587998674-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2587998674-7">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="2587998674-7">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2587998674-8">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="2587998674-8">]</span><span class="p" data-group-id="2587998674-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2587998674-9">[</span><span class="n">Map</span><span class="p" data-group-id="2587998674-10">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2587998674-10">)</span><span class="p">|</span><span class="nf">map_pairs2</span><span class="p" data-group-id="2587998674-11">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="2587998674-11">)</span><span class="p" data-group-id="2587998674-9">]</span><span class="p">.</span></code></pre><p>The compiler will generate code similar to this:</p><p><strong>DO NOT (already done by the compiler)</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="3851680787-1">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs0</span><span class="p">,</span><span class="w"> </span><span class="n">Ys0</span><span class="p" data-group-id="3851680787-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Xs0</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="3996410128-2">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="3996410128-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="3851680787-2">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="3851680787-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  	    </span><span class="k">case</span><span class="w"> </span><span class="n">Ys0</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="3996410128-3">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="3996410128-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="p" data-group-id="3996410128-4">[</span><span class="n">Map</span><span class="p" data-group-id="3996410128-5">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3996410128-5">)</span><span class="p">|</span><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="3996410128-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="3996410128-6">)</span><span class="p" data-group-id="3996410128-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="3996410128-7">[</span><span class="p" data-group-id="3996410128-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="3851680787-3">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="3851680787-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="p" data-group-id="3851680787-4">[</span><span class="n">Map</span><span class="p" data-group-id="3851680787-5">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3851680787-5">)</span><span class="p">|</span><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="3851680787-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="3851680787-6">)</span><span class="p" data-group-id="3851680787-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="3851680787-7">[</span><span class="p" data-group-id="3851680787-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  		    </span><span class="n">Xs0</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="3996410128-8">[</span><span class="p" data-group-id="3996410128-8">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="3851680787-8">[</span><span class="p" data-group-id="3851680787-8">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  	    </span><span class="n">Ys0</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>This is slightly faster for probably the most common case that the input lists
│ │ │ │  are not empty or very short. (Another advantage is that Dialyzer can deduce a
│ │ │ │  better type for the <code class="inline">Xs</code> variable.)</p><h2 id="function-calls" class="section-heading">
│ │ │ │    <a href="#function-calls" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ ├── OEBPS/drivers.xhtml
│ │ │ │ @@ -27,23 +27,23 @@
│ │ │ │    <span class="text">Drivers and Concurrency</span>
│ │ │ │  </h2>
│ │ │ │  <p>The runtime system always takes a lock before running any code in a driver.</p><p>By default, that lock is at the driver level, that is, if several ports have
│ │ │ │  been opened to the same driver, only code for one port at the same time can be
│ │ │ │  running.</p><p>A driver can be configured to have one lock for each port instead.</p><p>If a driver is used in a functional way (that is, holds no state, but only does
│ │ │ │  some heavy calculation and returns a result), several ports with registered
│ │ │ │  names can be opened beforehand, and the port to be used can be chosen based on
│ │ │ │ -the scheduler ID as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2404752682-1">(</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="2404752682-2">(</span><span class="p" data-group-id="2404752682-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="2404752682-3">{</span><span class="ss">some_driver_01</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_02</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_03</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_04</span><span class="p">,</span><span class="w">
│ │ │ │ +the scheduler ID as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="4184097964-1">(</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="4184097964-2">(</span><span class="p" data-group-id="4184097964-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="4184097964-3">{</span><span class="ss">some_driver_01</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_02</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_03</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_04</span><span class="p">,</span><span class="w">
│ │ │ │  	 </span><span class="ss">some_driver_05</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_06</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_07</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_08</span><span class="p">,</span><span class="w">
│ │ │ │  	 </span><span class="ss">some_driver_09</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_10</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_11</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_12</span><span class="p">,</span><span class="w">
│ │ │ │ -	 </span><span class="ss">some_driver_13</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_14</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_15</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_16</span><span class="p" data-group-id="2404752682-3">}</span><span class="p" data-group-id="2404752682-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +	 </span><span class="ss">some_driver_13</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_14</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_15</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_16</span><span class="p" data-group-id="4184097964-3">}</span><span class="p" data-group-id="4184097964-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">client_port</span><span class="p" data-group-id="2404752682-4">(</span><span class="p" data-group-id="2404752682-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">element</span><span class="p" data-group-id="2404752682-5">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="2404752682-6">(</span><span class="ss">scheduler_id</span><span class="p" data-group-id="2404752682-6">)</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="2404752682-7">(</span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="2404752682-8">(</span><span class="p" data-group-id="2404752682-8">)</span><span class="p" data-group-id="2404752682-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w">
│ │ │ │ -	    </span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="2404752682-9">(</span><span class="p" data-group-id="2404752682-9">)</span><span class="p" data-group-id="2404752682-5">)</span><span class="p">.</span></code></pre><p>As long as there are no more than 16 schedulers, there will never be any lock
│ │ │ │ +</span><span class="nf">client_port</span><span class="p" data-group-id="4184097964-4">(</span><span class="p" data-group-id="4184097964-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">element</span><span class="p" data-group-id="4184097964-5">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="4184097964-6">(</span><span class="ss">scheduler_id</span><span class="p" data-group-id="4184097964-6">)</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="4184097964-7">(</span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="4184097964-8">(</span><span class="p" data-group-id="4184097964-8">)</span><span class="p" data-group-id="4184097964-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="4184097964-9">(</span><span class="p" data-group-id="4184097964-9">)</span><span class="p" data-group-id="4184097964-5">)</span><span class="p">.</span></code></pre><p>As long as there are no more than 16 schedulers, there will never be any lock
│ │ │ │  contention on the port lock for the driver.</p><h2 id="avoiding-copying-binaries-when-calling-a-driver" class="section-heading">
│ │ │ │    <a href="#avoiding-copying-binaries-when-calling-a-driver" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Avoiding Copying Binaries When Calling a Driver</span>
│ │ │ │  </h2>
│ │ │ │  <p>There are basically two ways to avoid copying a binary that is sent to a driver:</p><ul><li><p>If the <code class="inline">Data</code> argument for <a href="../../../lib/../erts/doc/html/erlang.html#port_control/3"><code class="inline">port_control/3</code></a> is a
│ │ │ ├── OEBPS/documentation.xhtml
│ │ │ │ @@ -17,23 +17,23 @@
│ │ │ │    </head>
│ │ │ │    <body class="content-inner">
│ │ │ │  
│ │ │ │      <h1 id="content">
│ │ │ │  Documentation
│ │ │ │      </h1>
│ │ │ │  <p>Documentation in Erlang is done through the <code class="inline">-moduledoc</code> and <code class="inline">-doc</code>
│ │ │ │ -<a href="modules.xhtml#module-attributes">attributes</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0592734836-1">(</span><span class="ss">arith</span><span class="p" data-group-id="0592734836-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<a href="modules.xhtml#module-attributes">attributes</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6809040149-1">(</span><span class="ss">arith</span><span class="p" data-group-id="6809040149-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │ │  A module for basic arithmetic.
│ │ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0592734836-2">(</span><span class="p" data-group-id="0592734836-3">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0592734836-3">]</span><span class="p" data-group-id="0592734836-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6809040149-2">(</span><span class="p" data-group-id="6809040149-3">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6809040149-3">]</span><span class="p" data-group-id="6809040149-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;Adds two numbers.&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="0592734836-4">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="0592734836-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The <code class="inline">-moduledoc</code> attribute has to be located before the first <code class="inline">-doc</code> attribute
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="6809040149-4">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="6809040149-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The <code class="inline">-moduledoc</code> attribute has to be located before the first <code class="inline">-doc</code> attribute
│ │ │ │  or function declaration. It documents the overall purpose of the module.</p><p>The <code class="inline">-doc</code> attribute always precedes the <a href="ref_man_functions.xhtml">function</a> or
│ │ │ │  <a href="modules.xhtml#module-attributes">attribute</a> it documents. The
│ │ │ │  attributes that can be documented are
│ │ │ │  <a href="typespec.xhtml#type-declarations-of-user-defined-types">user-defined types</a>
│ │ │ │  (<code class="inline">-type</code> and <code class="inline">-opaque</code>) and
│ │ │ │  <a href="modules.xhtml#behaviour-module-attribute">behaviour module attributes</a>
│ │ │ │  (<code class="inline">-callback</code>).</p><p>By default the format used for documentation attributes is
│ │ │ │ @@ -45,55 +45,55 @@
│ │ │ │  <a href="modules.xhtml#documentation-attributes">Documentation Attributes</a>.</p><p><code class="inline">-doc</code> attributes have been available since Erlang/OTP 27.</p><h2 id="documentation-metadata" class="section-heading">
│ │ │ │    <a href="#documentation-metadata" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Documentation metadata</span>
│ │ │ │  </h2>
│ │ │ │  <p>It is possible to add metadata to the documentation entry. You do this by adding
│ │ │ │ -a <code class="inline">-moduledoc</code> or <code class="inline">-doc</code> attribute with a map as argument. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9999615289-1">(</span><span class="ss">arith</span><span class="p" data-group-id="9999615289-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +a <code class="inline">-moduledoc</code> or <code class="inline">-doc</code> attribute with a map as argument. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4701882928-1">(</span><span class="ss">arith</span><span class="p" data-group-id="4701882928-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │ │  A module for basic arithmetic.
│ │ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="9999615289-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="9999615289-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="4701882928-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="4701882928-2">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9999615289-3">(</span><span class="p" data-group-id="9999615289-4">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9999615289-4">]</span><span class="p" data-group-id="9999615289-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4701882928-3">(</span><span class="p" data-group-id="4701882928-4">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="4701882928-4">]</span><span class="p" data-group-id="4701882928-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;Adds two numbers.&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="9999615289-5">(</span><span class="p" data-group-id="9999615289-6">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="9999615289-6">}</span><span class="p" data-group-id="9999615289-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="9999615289-7">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="9999615289-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The metadata is used by documentation tools to provide extra information to the
│ │ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="4701882928-5">(</span><span class="p" data-group-id="4701882928-6">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="4701882928-6">}</span><span class="p" data-group-id="4701882928-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="4701882928-7">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="4701882928-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The metadata is used by documentation tools to provide extra information to the
│ │ │ │  user. There can be multiple metadata documentation entries, in which case the
│ │ │ │  maps will be merged with the latest taking precedence if there are duplicate
│ │ │ │  keys. Example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;Adds two numbers.&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="1629582079-1">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">author</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p" data-group-id="1629582079-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="1629582079-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="1629582079-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="1629582079-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="1629582079-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>This will result in a metadata entry of <code class="inline">#{since =&gt; &quot;2.0&quot;, author =&gt; &quot;Joe&quot;}</code>.</p><p>The keys and values in the metadata map can be any type, but it is recommended
│ │ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="5885845047-1">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">author</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p" data-group-id="5885845047-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="5885845047-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="5885845047-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="5885845047-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5885845047-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>This will result in a metadata entry of <code class="inline">#{since =&gt; &quot;2.0&quot;, author =&gt; &quot;Joe&quot;}</code>.</p><p>The keys and values in the metadata map can be any type, but it is recommended
│ │ │ │  that only <a href="data_types.xhtml#atom">atoms</a> are used for keys and
│ │ │ │  <a href="data_types.xhtml#string">strings</a> for the values.</p><h2 id="external-documentation-files" class="section-heading">
│ │ │ │    <a href="#external-documentation-files" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">External documentation files</span>
│ │ │ │  </h2>
│ │ │ │  <p>The <code class="inline">-moduledoc</code> and <code class="inline">-doc</code> can also be placed in external files. To do so use
│ │ │ │  <code class="inline">-doc {file, &quot;path/to/doc.md&quot;}</code> to point to the documentation. The path used is
│ │ │ │  relative to the file where the <code class="inline">-doc</code> attribute is located. For example:</p><pre><code class="markdown">%% doc/add.md
│ │ │ │  Adds two numbers.</code></pre><p>and</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% src/arith.erl</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="2523480824-1">(</span><span class="p" data-group-id="2523480824-2">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/add.md&quot;</span><span class="p" data-group-id="2523480824-2">}</span><span class="p" data-group-id="2523480824-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="2523480824-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="2523480824-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><h2 id="documenting-a-module" class="section-heading">
│ │ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="8108582554-1">(</span><span class="p" data-group-id="8108582554-2">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/add.md&quot;</span><span class="p" data-group-id="8108582554-2">}</span><span class="p" data-group-id="8108582554-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="8108582554-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="8108582554-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><h2 id="documenting-a-module" class="section-heading">
│ │ │ │    <a href="#documenting-a-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Documenting a module</span>
│ │ │ │  </h2>
│ │ │ │  <p>The module description should include details on how to use the API and examples
│ │ │ │  of the different functions working together. Here is a good place to use images
│ │ │ │  and other diagrams to better show the usage of the module. Instead of writing a
│ │ │ │  long text in the <code class="inline">moduledoc</code> attribute, it could be better to break it out into
│ │ │ │  an external page.</p><p>The <code class="inline">moduledoc</code> attribute should start with a short paragraph describing the
│ │ │ │ -module and then go into greater details. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7696417456-1">(</span><span class="ss">arith</span><span class="p" data-group-id="7696417456-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +module and then go into greater details. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2384538848-1">(</span><span class="ss">arith</span><span class="p" data-group-id="2384538848-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="s">&quot;
│ │ │ │     A module for basic arithmetic.
│ │ │ │  
│ │ │ │     This module can be used to add and subtract values. For example:
│ │ │ │  
│ │ │ │     ```erlang
│ │ │ │     1&gt; arith:substract(arith:add(2, 3), 1).
│ │ │ │ @@ -108,94 +108,94 @@
│ │ │ │  <p>There are three reserved metadata keys for <code class="inline">-moduledoc</code>:</p><ul><li><code class="inline">since</code> - Shows in which version of the application the module was added.
│ │ │ │  If this is added, all functions, types, and callbacks within will also receive
│ │ │ │  the same <code class="inline">since</code> value unless specified in the metadata of the function, type
│ │ │ │  or callback.</li><li><code class="inline">deprecated</code> - Shows a text in the documentation explaining that it is
│ │ │ │  deprecated and what to use instead.</li><li><code class="inline">format</code> - The format to use for all documentation in this module. The
│ │ │ │  default is <code class="inline">text/markdown</code>. It should be written using the
│ │ │ │  <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types">mime type</a>
│ │ │ │ -of the format.</li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="1510176123-1">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/arith.asciidoc&quot;</span><span class="p" data-group-id="1510176123-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="1510176123-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;0.1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">format</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;text/asciidoc&quot;</span><span class="p" data-group-id="1510176123-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="1510176123-3">#{</span><span class="ss">deprecated</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Use the Erlang arithmetic operators instead.&quot;</span><span class="p" data-group-id="1510176123-3">}</span><span class="p">.</span></code></pre><h2 id="documenting-functions-user-defined-types-and-callbacks" class="section-heading">
│ │ │ │ +of the format.</li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="1326345230-1">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/arith.asciidoc&quot;</span><span class="p" data-group-id="1326345230-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="1326345230-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;0.1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">format</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;text/asciidoc&quot;</span><span class="p" data-group-id="1326345230-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="1326345230-3">#{</span><span class="ss">deprecated</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Use the Erlang arithmetic operators instead.&quot;</span><span class="p" data-group-id="1326345230-3">}</span><span class="p">.</span></code></pre><h2 id="documenting-functions-user-defined-types-and-callbacks" class="section-heading">
│ │ │ │    <a href="#documenting-functions-user-defined-types-and-callbacks" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Documenting functions, user-defined types, and callbacks</span>
│ │ │ │  </h2>
│ │ │ │  <p>Functions, types, and callbacks can be documented using the <code class="inline">-doc</code> attribute.
│ │ │ │  Each entry should start with a short paragraph describing the purpose of entity,
│ │ │ │  and then go into greater detail in needed.</p><p>It is not recommended to include images or diagrams in this documentation as it
│ │ │ │  is used by IDEs and <a href="../../../lib/stdlib/doc/html/c.html#h/1"><code class="inline">c:h/1</code></a> to show the documentation to the user.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │ │  A number that can be used by the arith module.
│ │ │ │  
│ │ │ │  We use a special number here so that we know
│ │ │ │  that this number comes from this module.
│ │ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="5600560897-1">(</span><span class="p" data-group-id="5600560897-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="5600560897-2">{</span><span class="ss">arith</span><span class="p">,</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">number</span><span class="p" data-group-id="5600560897-3">(</span><span class="p" data-group-id="5600560897-3">)</span><span class="p" data-group-id="5600560897-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="9047043375-1">(</span><span class="p" data-group-id="9047043375-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="9047043375-2">{</span><span class="ss">arith</span><span class="p">,</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">number</span><span class="p" data-group-id="9047043375-3">(</span><span class="p" data-group-id="9047043375-3">)</span><span class="p" data-group-id="9047043375-2">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │ │  Adds two numbers.
│ │ │ │  
│ │ │ │  ### Example:
│ │ │ │  
│ │ │ │  ```
│ │ │ │  1&gt; arith:add(arith:number(1), arith:number(2)). {number, 3}
│ │ │ │  ```
│ │ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="5600560897-4">(</span><span class="nf">number</span><span class="p" data-group-id="5600560897-5">(</span><span class="p" data-group-id="5600560897-5">)</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="5600560897-6">(</span><span class="p" data-group-id="5600560897-6">)</span><span class="p" data-group-id="5600560897-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="5600560897-7">(</span><span class="p" data-group-id="5600560897-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="5600560897-8">(</span><span class="p" data-group-id="5600560897-9">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="p" data-group-id="5600560897-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5600560897-10">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5600560897-10">}</span><span class="p" data-group-id="5600560897-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5600560897-11">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5600560897-11">}</span><span class="p">.</span></code></pre><h3 id="doc-metadata" class="section-heading">
│ │ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="9047043375-4">(</span><span class="nf">number</span><span class="p" data-group-id="9047043375-5">(</span><span class="p" data-group-id="9047043375-5">)</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="9047043375-6">(</span><span class="p" data-group-id="9047043375-6">)</span><span class="p" data-group-id="9047043375-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="9047043375-7">(</span><span class="p" data-group-id="9047043375-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="9047043375-8">(</span><span class="p" data-group-id="9047043375-9">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="p" data-group-id="9047043375-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9047043375-10">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="9047043375-10">}</span><span class="p" data-group-id="9047043375-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9047043375-11">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="9047043375-11">}</span><span class="p">.</span></code></pre><h3 id="doc-metadata" class="section-heading">
│ │ │ │    <a href="#doc-metadata" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Doc metadata</span>
│ │ │ │  </h3>
│ │ │ │  <p>There are four reserved metadata keys for <code class="inline">-doc</code>:</p><ul><li><p><code class="inline">since =&gt; unicode:chardata()</code> - Shows which version of the application the
│ │ │ │  module was added.</p></li><li><p><code class="inline">deprecated =&gt; unicode:chardata()</code> - Shows a text in the documentation
│ │ │ │  explaining that it is deprecated and what to use instead. The compiler will
│ │ │ │  automatically insert this key if there is a <code class="inline">-deprecated</code> attribute marking a
│ │ │ │  function as deprecated.</p></li><li><p><code class="inline">equiv =&gt; unicode:chardata() | F/A | F(...)</code> - Notes that this function is equivalent to
│ │ │ │  another function in this module. The equivalence can be described using either
│ │ │ │ -<code class="inline">Func/Arity</code>, <code class="inline">Func(Args)</code> or a <a href="../../../lib/stdlib/doc/html/unicode.html#t:chardata/0">unicode string</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="5107115185-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">add</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5107115185-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="5107115185-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5107115185-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="5107115185-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5107115185-4">[</span><span class="p" data-group-id="5107115185-4">]</span><span class="p" data-group-id="5107115185-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="5107115185-5">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="5107115185-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>or</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="8542657385-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="8542657385-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8542657385-3">[</span><span class="p" data-group-id="8542657385-3">]</span><span class="p" data-group-id="8542657385-2">)</span><span class="p" data-group-id="8542657385-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="8542657385-4">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8542657385-5">(</span><span class="p" data-group-id="8542657385-5">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8542657385-6">(</span><span class="p" data-group-id="8542657385-6">)</span><span class="p" data-group-id="8542657385-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8542657385-7">(</span><span class="p" data-group-id="8542657385-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="8542657385-8">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="8542657385-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="8542657385-9">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8542657385-10">[</span><span class="p" data-group-id="8542657385-10">]</span><span class="p" data-group-id="8542657385-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="8542657385-11">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="8542657385-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The entry into the <a href="../../../lib/kernel/doc/html/eep48_chapter.xhtml">EEP-48</a> doc chunk metadata is
│ │ │ │ +<code class="inline">Func/Arity</code>, <code class="inline">Func(Args)</code> or a <a href="../../../lib/stdlib/doc/html/unicode.html#t:chardata/0">unicode string</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="5637280040-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">add</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5637280040-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="5637280040-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5637280040-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="5637280040-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5637280040-4">[</span><span class="p" data-group-id="5637280040-4">]</span><span class="p" data-group-id="5637280040-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="5637280040-5">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="5637280040-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>or</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="1055297019-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="1055297019-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1055297019-3">[</span><span class="p" data-group-id="1055297019-3">]</span><span class="p" data-group-id="1055297019-2">)</span><span class="p" data-group-id="1055297019-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="1055297019-4">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="1055297019-5">(</span><span class="p" data-group-id="1055297019-5">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="1055297019-6">(</span><span class="p" data-group-id="1055297019-6">)</span><span class="p" data-group-id="1055297019-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="1055297019-7">(</span><span class="p" data-group-id="1055297019-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="1055297019-8">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="1055297019-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="1055297019-9">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1055297019-10">[</span><span class="p" data-group-id="1055297019-10">]</span><span class="p" data-group-id="1055297019-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="1055297019-11">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="1055297019-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The entry into the <a href="../../../lib/kernel/doc/html/eep48_chapter.xhtml">EEP-48</a> doc chunk metadata is
│ │ │ │  the value converted to a string.</p></li><li><p><code class="inline">exported =&gt; boolean()</code> - A <a href="../../../lib/../erts/doc/html/erlang.html#t:boolean/0"><code class="inline">boolean/0</code></a> signifying if the entry is <code class="inline">exported</code>
│ │ │ │  or not. This value is automatically set by the compiler and should not be set
│ │ │ │  by the user.</p></li></ul><h3 id="doc-signatures" class="section-heading">
│ │ │ │    <a href="#doc-signatures" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Doc signatures</span>
│ │ │ │  </h3>
│ │ │ │  <p>The doc signature is a short text shown to describe the function and its arguments.
│ │ │ │  By default it is determined by looking at the names of the arguments in the
│ │ │ │ -<code class="inline">-spec</code> or function. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add</span><span class="p" data-group-id="3023988439-1">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="3023988439-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">-spec</code> or function. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add</span><span class="p" data-group-id="2720295587-1">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="2720295587-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">sub</span><span class="p" data-group-id="3023988439-2">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="3023988439-3">(</span><span class="p" data-group-id="3023988439-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="3023988439-4">(</span><span class="p" data-group-id="3023988439-4">)</span><span class="p" data-group-id="3023988439-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="3023988439-5">(</span><span class="p" data-group-id="3023988439-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">sub</span><span class="p" data-group-id="3023988439-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3023988439-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span></code></pre><p>will have a signature of <code class="inline">add(One, Two)</code> and <code class="inline">sub(One, Two)</code>.</p><p>For types or callbacks, the signature is derived from the type or callback
│ │ │ │ -specification. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="0882034645-1">(</span><span class="n">Value</span><span class="p" data-group-id="0882034645-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="0882034645-2">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="0882034645-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">sub</span><span class="p" data-group-id="2720295587-2">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="2720295587-3">(</span><span class="p" data-group-id="2720295587-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="2720295587-4">(</span><span class="p" data-group-id="2720295587-4">)</span><span class="p" data-group-id="2720295587-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="2720295587-5">(</span><span class="p" data-group-id="2720295587-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">sub</span><span class="p" data-group-id="2720295587-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2720295587-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span></code></pre><p>will have a signature of <code class="inline">add(One, Two)</code> and <code class="inline">sub(One, Two)</code>.</p><p>For types or callbacks, the signature is derived from the type or callback
│ │ │ │ +specification. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8968498816-1">(</span><span class="n">Value</span><span class="p" data-group-id="8968498816-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="8968498816-2">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="8968498816-2">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% signature will be `number(Value)`</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="0882034645-3">(</span><span class="p" data-group-id="0882034645-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="0882034645-4">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="0882034645-5">(</span><span class="p" data-group-id="0882034645-5">)</span><span class="p" data-group-id="0882034645-4">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8968498816-3">(</span><span class="p" data-group-id="8968498816-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="8968498816-4">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8968498816-5">(</span><span class="p" data-group-id="8968498816-5">)</span><span class="p" data-group-id="8968498816-4">}</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% signature will be `number()`</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="0882034645-6">(</span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="0882034645-7">(</span><span class="p" data-group-id="0882034645-7">)</span><span class="p" data-group-id="0882034645-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="8968498816-6">(</span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8968498816-7">(</span><span class="p" data-group-id="8968498816-7">)</span><span class="p" data-group-id="8968498816-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% signature will be `increment(In)`</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="0882034645-8">(</span><span class="n">In</span><span class="p" data-group-id="0882034645-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="0882034645-9">(</span><span class="p" data-group-id="0882034645-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="8968498816-8">(</span><span class="n">In</span><span class="p" data-group-id="8968498816-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8968498816-9">(</span><span class="p" data-group-id="8968498816-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%% signature will be `increment(In)`</span></code></pre><p>If it is not possible to &quot;easily&quot; figure out a nice signature from the code, the
│ │ │ │  MFA syntax is used instead. For example: <code class="inline">add/2</code>, <code class="inline">number/1</code>, <code class="inline">increment/1</code></p><p>It is possible to supply a custom signature by placing it as the first line of the
│ │ │ │  <code class="inline">-doc</code> attribute. The provided signature must be in the form of a function
│ │ │ │  declaration up until the <code class="inline">-&gt;</code>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │ │  add(One, Two)
│ │ │ │  
│ │ │ │  Adds two numbers.
│ │ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="7345874174-1">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="7345874174-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p">.</span></code></pre><p>Will create the signature <code class="inline">add(One, Two)</code>. The signature will be removed from the
│ │ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="2346982561-1">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="2346982561-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p">.</span></code></pre><p>Will create the signature <code class="inline">add(One, Two)</code>. The signature will be removed from the
│ │ │ │  documentation string, so in the example above only the text <code class="inline">&quot;Adds two numbers&quot;</code>
│ │ │ │  will be part of the documentation. This works for functions, types, and
│ │ │ │  callbacks.</p><h2 id="links-in-markdown" class="section-heading">
│ │ │ │    <a href="#links-in-markdown" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Links in Markdown</span>
│ │ │ │ @@ -233,28 +233,28 @@
│ │ │ │  modules. That is, modules that should be used by other applications and modules
│ │ │ │  that should not. By default all modules in an application are visible, but by
│ │ │ │  setting <code class="inline">-moduledoc false.</code> specific modules can be hidden from being listed as
│ │ │ │  part of the available API.</p><p>An Erlang <a href="modules.xhtml">module</a> consists of public and private functions and type
│ │ │ │  attributes. By default, all exported functions, exported types and callbacks are
│ │ │ │  considered visible and part of the modules public API. In addition, any
│ │ │ │  non-exported type that is referred to by any other visible type attribute is
│ │ │ │ -also visible, but not considered to be part of the public API. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9550007975-1">(</span><span class="p" data-group-id="9550007975-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9550007975-2">]</span><span class="p" data-group-id="9550007975-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +also visible, but not considered to be part of the public API. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9354995736-1">(</span><span class="p" data-group-id="9354995736-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9354995736-2">]</span><span class="p" data-group-id="9354995736-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="9550007975-3">(</span><span class="p" data-group-id="9550007975-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="9550007975-4">(</span><span class="p" data-group-id="9550007975-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="9550007975-5">(</span><span class="p" data-group-id="9550007975-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">example</span><span class="p" data-group-id="9550007975-6">(</span><span class="p" data-group-id="9550007975-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>in the above code, the function <code class="inline">example/0</code> is exported and it referenced the
│ │ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="9354995736-3">(</span><span class="p" data-group-id="9354995736-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="9354995736-4">(</span><span class="p" data-group-id="9354995736-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="9354995736-5">(</span><span class="p" data-group-id="9354995736-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">example</span><span class="p" data-group-id="9354995736-6">(</span><span class="p" data-group-id="9354995736-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>in the above code, the function <code class="inline">example/0</code> is exported and it referenced the
│ │ │ │  un-exported type <code class="inline">private/0</code>. Therefore both <code class="inline">example/0</code> and <code class="inline">private/0</code> will be
│ │ │ │  marked as visible. The <code class="inline">private/0</code> type will have the metadata field <code class="inline">exported</code>
│ │ │ │  set to <code class="inline">false</code> to show that it is not part of the public API.</p><p>If you want to make a visible entity hidden you need to set the <code class="inline">-doc</code> attribute
│ │ │ │ -to <code class="inline">false</code>. Let us revisit our previous example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7985146836-1">(</span><span class="p" data-group-id="7985146836-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7985146836-2">]</span><span class="p" data-group-id="7985146836-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +to <code class="inline">false</code>. Let us revisit our previous example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0297746287-1">(</span><span class="p" data-group-id="0297746287-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0297746287-2">]</span><span class="p" data-group-id="0297746287-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="7985146836-3">(</span><span class="p" data-group-id="7985146836-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="7985146836-4">(</span><span class="p" data-group-id="7985146836-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="7985146836-5">(</span><span class="p" data-group-id="7985146836-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="0297746287-3">(</span><span class="p" data-group-id="0297746287-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="0297746287-4">(</span><span class="p" data-group-id="0297746287-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="0297746287-5">(</span><span class="p" data-group-id="0297746287-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="ss">false</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">example</span><span class="p" data-group-id="7985146836-6">(</span><span class="p" data-group-id="7985146836-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>The function <code class="inline">example/0</code> is exported but explicitly marked as hidden; therefore
│ │ │ │ +</span><span class="nf">example</span><span class="p" data-group-id="0297746287-6">(</span><span class="p" data-group-id="0297746287-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>The function <code class="inline">example/0</code> is exported but explicitly marked as hidden; therefore
│ │ │ │  both <code class="inline">example/0</code> and <code class="inline">private/0</code> will be hidden.</p><p>Any documentation added to an automatically hidden entity (non-exported function
│ │ │ │  or type) is ignored and will generate a warning. Such functions can be
│ │ │ │  documented using comments.</p><h2 id="compiling-and-getting-documentation" class="section-heading">
│ │ │ │    <a href="#compiling-and-getting-documentation" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Compiling and getting documentation</span>
│ │ │ │ @@ -280,21 +280,21 @@
│ │ │ │    <span class="text">Using ExDoc to generate HTML/ePub documentation</span>
│ │ │ │  </h2>
│ │ │ │  <p><a href="https://hexdocs.pm/ex_doc/">ExDoc</a> has built-in support to generate
│ │ │ │  documentation from Markdown. The simplest way is by using the
│ │ │ │  <a href="https://hexdocs.pm/rebar3_ex_doc">rebar3_ex_doc</a> plugin. To set up a
│ │ │ │  rebar3 project to use <a href="https://hexdocs.pm/ex_doc/">ExDoc</a> to generate
│ │ │ │  documentation add the following to your <code class="inline">rebar3.config</code>.</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Enable the plugin</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5161286217-1">{</span><span class="ss">plugins</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5161286217-2">[</span><span class="ss">rebar3_ex_doc</span><span class="p" data-group-id="5161286217-2">]</span><span class="p" data-group-id="5161286217-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1061502246-1">{</span><span class="ss">plugins</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1061502246-2">[</span><span class="ss">rebar3_ex_doc</span><span class="p" data-group-id="1061502246-2">]</span><span class="p" data-group-id="1061502246-1">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="p" data-group-id="5161286217-3">{</span><span class="ss">ex_doc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5161286217-4">[</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5161286217-5">{</span><span class="ss">extras</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5161286217-6">[</span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="5161286217-6">]</span><span class="p" data-group-id="5161286217-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5161286217-7">{</span><span class="ss">main</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="5161286217-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="5161286217-8">{</span><span class="ss">source_url</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;https://github.com/namespace/your_app&quot;</span><span class="p" data-group-id="5161286217-8">}</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5161286217-4">]</span><span class="p" data-group-id="5161286217-3">}</span><span class="p">.</span></code></pre><p>When configured you can run <code class="inline">rebar3 ex_doc</code> to generate the
│ │ │ │ +</span><span class="p" data-group-id="1061502246-3">{</span><span class="ss">ex_doc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1061502246-4">[</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="1061502246-5">{</span><span class="ss">extras</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1061502246-6">[</span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="1061502246-6">]</span><span class="p" data-group-id="1061502246-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="1061502246-7">{</span><span class="ss">main</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="1061502246-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="1061502246-8">{</span><span class="ss">source_url</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;https://github.com/namespace/your_app&quot;</span><span class="p" data-group-id="1061502246-8">}</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1061502246-4">]</span><span class="p" data-group-id="1061502246-3">}</span><span class="p">.</span></code></pre><p>When configured you can run <code class="inline">rebar3 ex_doc</code> to generate the
│ │ │ │  documentation to <code class="inline">doc/index.html</code>. For more details and options see
│ │ │ │  the <a href="https://hexdocs.pm/rebar3_ex_doc">rebar3_ex_doc</a> documentation.</p><p>You can also download the
│ │ │ │  <a href="https://github.com/elixir/ex_doc/releases/latest">release escript bundle</a> from
│ │ │ │  github and run it from the command line. The documentation for using the escript
│ │ │ │  is found by running <code class="inline">ex_doc --help</code>.</p><p>If you are writing documentation that will be using
│ │ │ │  <a href="https://hexdocs.pm/ex_doc/">ExDoc</a> to generate HTML/ePub it is highly
│ │ │ │  recommended to read its documentation.</p>
│ │ │ ├── OEBPS/distributed_applications.xhtml
│ │ │ │ @@ -55,36 +55,36 @@
│ │ │ │  (within the time-out specified by <code class="inline">sync_nodes_timeout</code>).</li><li><p><code class="inline">sync_nodes_timeout = integer() | infinity</code> - Specifies how many milliseconds
│ │ │ │  to wait for the other nodes to start.</p></li></ul><p>When started, the node waits for all nodes specified by <code class="inline">sync_nodes_mandatory</code>
│ │ │ │  and <code class="inline">sync_nodes_optional</code> to come up. When all nodes are up, or when all
│ │ │ │  mandatory nodes are up and the time specified by <code class="inline">sync_nodes_timeout</code> has
│ │ │ │  elapsed, all applications start. If not all mandatory nodes are up, the node
│ │ │ │  terminates.</p><p><em>Example:</em></p><p>An application <code class="inline">myapp</code> is to run at the node <code class="inline">cp1@cave</code>. If this node goes down,
│ │ │ │  <code class="inline">myapp</code> is to be restarted at <code class="inline">cp2@cave</code> or <code class="inline">cp3@cave</code>. A system configuration
│ │ │ │ -file <code class="inline">cp1.config</code> for <code class="inline">cp1@cave</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1254754795-1">[</span><span class="p" data-group-id="1254754795-2">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1254754795-3">[</span><span class="p" data-group-id="1254754795-4">{</span><span class="ss">distributed</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1254754795-5">[</span><span class="p" data-group-id="1254754795-6">{</span><span class="ss">myapp</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1254754795-7">[</span><span class="ss">cp1@cave</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1254754795-8">{</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="1254754795-8">}</span><span class="p" data-group-id="1254754795-7">]</span><span class="p" data-group-id="1254754795-6">}</span><span class="p" data-group-id="1254754795-5">]</span><span class="p" data-group-id="1254754795-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="1254754795-9">{</span><span class="ss">sync_nodes_mandatory</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1254754795-10">[</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="1254754795-10">]</span><span class="p" data-group-id="1254754795-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="1254754795-11">{</span><span class="ss">sync_nodes_timeout</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p" data-group-id="1254754795-11">}</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1254754795-3">]</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1254754795-2">}</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1254754795-1">]</span><span class="p">.</span></code></pre><p>The system configuration files for <code class="inline">cp2@cave</code> and <code class="inline">cp3@cave</code> are identical,
│ │ │ │ +file <code class="inline">cp1.config</code> for <code class="inline">cp1@cave</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1186636125-1">[</span><span class="p" data-group-id="1186636125-2">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="1186636125-3">[</span><span class="p" data-group-id="1186636125-4">{</span><span class="ss">distributed</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1186636125-5">[</span><span class="p" data-group-id="1186636125-6">{</span><span class="ss">myapp</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1186636125-7">[</span><span class="ss">cp1@cave</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1186636125-8">{</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="1186636125-8">}</span><span class="p" data-group-id="1186636125-7">]</span><span class="p" data-group-id="1186636125-6">}</span><span class="p" data-group-id="1186636125-5">]</span><span class="p" data-group-id="1186636125-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="1186636125-9">{</span><span class="ss">sync_nodes_mandatory</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1186636125-10">[</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="1186636125-10">]</span><span class="p" data-group-id="1186636125-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="1186636125-11">{</span><span class="ss">sync_nodes_timeout</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p" data-group-id="1186636125-11">}</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="1186636125-3">]</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="1186636125-2">}</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1186636125-1">]</span><span class="p">.</span></code></pre><p>The system configuration files for <code class="inline">cp2@cave</code> and <code class="inline">cp3@cave</code> are identical,
│ │ │ │  except for the list of mandatory nodes, which is to be <code class="inline">[cp1@cave, cp3@cave]</code>
│ │ │ │  for <code class="inline">cp2@cave</code> and <code class="inline">[cp1@cave, cp2@cave]</code> for <code class="inline">cp3@cave</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>All involved nodes must have the same value for <code class="inline">distributed</code> and
│ │ │ │  <code class="inline">sync_nodes_timeout</code>. Otherwise the system behavior is undefined.</p></section><h2 id="starting-and-stopping-distributed-applications" class="section-heading">
│ │ │ │    <a href="#starting-and-stopping-distributed-applications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting and Stopping Distributed Applications</span>
│ │ │ │  </h2>
│ │ │ │  <p>When all involved (mandatory) nodes have been started, the distributed
│ │ │ │  application can be started by calling <code class="inline">application:start(Application)</code> at <em>all
│ │ │ │  of these nodes.</em></p><p>A boot script (see <a href="release_structure.xhtml">Releases</a>) can be used that
│ │ │ │  automatically starts the application.</p><p>The application is started at the first operational node that is listed in the
│ │ │ │  list of nodes in the <code class="inline">distributed</code> configuration parameter. The application is
│ │ │ │  started as usual. That is, an application master is created and calls the
│ │ │ │ -application callback function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="3620318682-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="3620318682-1">)</span></code></pre><p>Example:</p><p>Continuing the example from the previous section, the three nodes are started,
│ │ │ │ +application callback function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2236768714-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="2236768714-1">)</span></code></pre><p>Example:</p><p>Continuing the example from the previous section, the three nodes are started,
│ │ │ │  specifying the system configuration file:</p><pre><code class="text">&gt; erl -sname cp1 -config cp1
│ │ │ │  &gt; erl -sname cp2 -config cp2
│ │ │ │  &gt; erl -sname cp3 -config cp3</code></pre><p>When all nodes are operational, <code class="inline">myapp</code> can be started. This is achieved by
│ │ │ │  calling <code class="inline">application:start(myapp)</code> at all three nodes. It is then started at
│ │ │ │  <code class="inline">cp1</code>, as shown in the following figure:</p><p><a href="" id="dist1"></a></p><p><img src="assets/dist1.gif" alt="Application myapp - Situation 1" title="Application myapp - Situation 1"/></p><p>Similarly, the application must be stopped by calling
│ │ │ │  <code class="inline">application:stop(Application)</code> at all involved nodes.</p><h2 id="failover" class="section-heading">
│ │ │ │    <a href="#failover" class="hover-link">
│ │ │ │ @@ -92,30 +92,30 @@
│ │ │ │    </a>
│ │ │ │    <span class="text">Failover</span>
│ │ │ │  </h2>
│ │ │ │  <p>If the node where the application is running goes down, the application is
│ │ │ │  restarted (after the specified time-out) at the first operational node that is
│ │ │ │  listed in the list of nodes in the <code class="inline">distributed</code> configuration parameter. This
│ │ │ │  is called a <em>failover</em>.</p><p>The application is started the normal way at the new node, that is, by the
│ │ │ │ -application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="1838112915-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="1838112915-1">)</span></code></pre><p>An exception is if the application has the <code class="inline">start_phases</code> key defined (see
│ │ │ │ +application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5055117539-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="5055117539-1">)</span></code></pre><p>An exception is if the application has the <code class="inline">start_phases</code> key defined (see
│ │ │ │  <a href="included_applications.xhtml">Included Applications</a>). The application is then
│ │ │ │ -instead started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="3357595871-1">(</span><span class="p" data-group-id="3357595871-2">{</span><span class="ss">failover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="3357595871-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="3357595871-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the terminated node.</p><p><em>Example:</em></p><p>If <code class="inline">cp1</code> goes down, the system checks which one of the other nodes, <code class="inline">cp2</code> or
│ │ │ │ +instead started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4026762105-1">(</span><span class="p" data-group-id="4026762105-2">{</span><span class="ss">failover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="4026762105-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="4026762105-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the terminated node.</p><p><em>Example:</em></p><p>If <code class="inline">cp1</code> goes down, the system checks which one of the other nodes, <code class="inline">cp2</code> or
│ │ │ │  <code class="inline">cp3</code>, has the least number of running applications, but waits for 5 seconds for
│ │ │ │  <code class="inline">cp1</code> to restart. If <code class="inline">cp1</code> does not restart and <code class="inline">cp2</code> runs fewer applications
│ │ │ │  than <code class="inline">cp3</code>, <code class="inline">myapp</code> is restarted on <code class="inline">cp2</code>.</p><p><a href="" id="dist2"></a></p><p><img src="assets/dist2.gif" alt="Application myapp - Situation 2" title="Application myapp - Situation 2"/></p><p>Suppose now that <code class="inline">cp2</code> goes also down and does not restart within 5 seconds.
│ │ │ │  <code class="inline">myapp</code> is now restarted on <code class="inline">cp3</code>.</p><p><a href="" id="dist3"></a></p><p><img src="assets/dist3.gif" alt="Application myapp - Situation 3" title="Application myapp - Situation 3"/></p><h2 id="takeover" class="section-heading">
│ │ │ │    <a href="#takeover" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Takeover</span>
│ │ │ │  </h2>
│ │ │ │  <p>If a node is started, which has higher priority according to <code class="inline">distributed</code> than
│ │ │ │  the node where a distributed application is running, the application is
│ │ │ │  restarted at the new node and stopped at the old node. This is called a
│ │ │ │ -<em>takeover</em>.</p><p>The application is started by the application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9272590077-1">(</span><span class="p" data-group-id="9272590077-2">{</span><span class="ss">takeover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="9272590077-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="9272590077-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the old node.</p><p><em>Example:</em></p><p>If <code class="inline">myapp</code> is running at <code class="inline">cp3</code>, and if <code class="inline">cp2</code> now restarts, it does not restart
│ │ │ │ +<em>takeover</em>.</p><p>The application is started by the application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9161915016-1">(</span><span class="p" data-group-id="9161915016-2">{</span><span class="ss">takeover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="9161915016-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="9161915016-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the old node.</p><p><em>Example:</em></p><p>If <code class="inline">myapp</code> is running at <code class="inline">cp3</code>, and if <code class="inline">cp2</code> now restarts, it does not restart
│ │ │ │  <code class="inline">myapp</code>, as the order between the <code class="inline">cp2</code> and <code class="inline">cp3</code> nodes is undefined.</p><p><a href="" id="dist4"></a></p><p><img src="assets/dist4.gif" alt="Application myapp - Situation 4" title="Application myapp - Situation 4"/></p><p>However, if <code class="inline">cp1</code> also restarts, the function <a href="../../../lib/kernel/doc/html/application.html#takeover/2"><code class="inline">application:takeover/2</code></a> moves
│ │ │ │  <code class="inline">myapp</code> to <code class="inline">cp1</code>, as <code class="inline">cp1</code> has a higher priority than <code class="inline">cp3</code> for this
│ │ │ │  application. In this case, <code class="inline">Module:start({takeover, cp3@cave}, StartArgs)</code> is
│ │ │ │  executed at <code class="inline">cp1</code> to start the application.</p><p><a href="" id="dist5"></a></p><p><img src="assets/dist5.gif" alt="Application myapp - Situation 5" title="Application myapp - Situation 5"/></p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/distributed.xhtml
│ │ │ │ @@ -47,25 +47,25 @@
│ │ │ │  </h2>
│ │ │ │  <p>A <em>node</em> is an executing Erlang runtime system that has been given a name, using
│ │ │ │  the command-line flag <a href="../../../lib/../erts/doc/html/erl_cmd.xhtml#name"><code class="inline">-name</code></a> (long names) or
│ │ │ │  <a href="../../../lib/../erts/doc/html/erl_cmd.xhtml#sname"><code class="inline">-sname</code></a> (short names).</p><p>The format of the node name is an atom <code class="inline">name@host</code>. <code class="inline">name</code> is the name given by
│ │ │ │  the user. <code class="inline">host</code> is the full host name if long names are used, or the first part
│ │ │ │  of the host name if short names are used. Function <a href="../../../lib/../erts/doc/html/erlang.html#node/0"><code class="inline">node()</code></a>
│ │ │ │  returns the name of the node.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -name dilbert</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5476788820-1">(</span><span class="ss">dilbert@uab</span><span class="p">.</span><span class="ss">ericsson</span><span class="p">.</span><span class="ss">se</span><span class="p" data-group-id="5476788820-1">)</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="5476788820-2">(</span><span class="p" data-group-id="5476788820-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5491371270-1">(</span><span class="ss">dilbert@uab</span><span class="p">.</span><span class="ss">ericsson</span><span class="p">.</span><span class="ss">se</span><span class="p" data-group-id="5491371270-1">)</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="5491371270-2">(</span><span class="p" data-group-id="5491371270-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">&#39;dilbert@uab.ericsson.se&#39;</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">% erl -sname dilbert</span><span class="gp unselectable">
│ │ │ │ -(dilbert@uab)1&gt; </span><span class="nf">node</span><span class="p" data-group-id="5476788820-3">(</span><span class="p" data-group-id="5476788820-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +(dilbert@uab)1&gt; </span><span class="nf">node</span><span class="p" data-group-id="5491371270-3">(</span><span class="p" data-group-id="5491371270-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">dilbert@uab</span></code></pre><p>The node name can also be given in runtime by calling <a href="../../../lib/kernel/doc/html/net_kernel.html#start/1"><code class="inline">net_kernel:start/1</code></a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nf">node</span><span class="p" data-group-id="7615238558-1">(</span><span class="p" data-group-id="7615238558-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +1&gt; </span><span class="nf">node</span><span class="p" data-group-id="5866138523-1">(</span><span class="p" data-group-id="5866138523-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">nonode@nohost</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">net_kernel</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7615238558-2">(</span><span class="p" data-group-id="7615238558-3">[</span><span class="ss">dilbert</span><span class="p">,</span><span class="ss">shortnames</span><span class="p" data-group-id="7615238558-3">]</span><span class="p" data-group-id="7615238558-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7615238558-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.102</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="7615238558-4">}</span><span class="gp unselectable">
│ │ │ │ -(dilbert@uab)3&gt; </span><span class="nf">node</span><span class="p" data-group-id="7615238558-5">(</span><span class="p" data-group-id="7615238558-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nc">net_kernel</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5866138523-2">(</span><span class="p" data-group-id="5866138523-3">[</span><span class="ss">dilbert</span><span class="p">,</span><span class="ss">shortnames</span><span class="p" data-group-id="5866138523-3">]</span><span class="p" data-group-id="5866138523-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5866138523-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.102</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5866138523-4">}</span><span class="gp unselectable">
│ │ │ │ +(dilbert@uab)3&gt; </span><span class="nf">node</span><span class="p" data-group-id="5866138523-5">(</span><span class="p" data-group-id="5866138523-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">dilbert@uab</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>A node with a long node name cannot communicate with a node with a short node
│ │ │ │  name.</p></section><h2 id="node-connections" class="section-heading">
│ │ │ │    <a href="#node-connections" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Node Connections</span>
│ │ │ │  </h2>
│ │ │ ├── OEBPS/design_principles.xhtml
│ │ │ │ @@ -57,135 +57,135 @@
│ │ │ │  the code for a process in a generic part (a behaviour module) and a specific
│ │ │ │  part (a <em>callback module</em>).</p><p>The behaviour module is part of Erlang/OTP. To implement a process such as a
│ │ │ │  supervisor, the user only needs to implement the callback module, which is to
│ │ │ │  export a pre-defined set of functions, the <em>callback functions</em>.</p><p>The following example illustrate how code can be divided into a generic and a
│ │ │ │  specific part. Consider the following code (written in plain Erlang) for a
│ │ │ │  simple server, which keeps track of a number of &quot;channels&quot;. Other processes can
│ │ │ │  allocate and free the channels by calling the functions <code class="inline">alloc/0</code> and <code class="inline">free/1</code>,
│ │ │ │ -respectively.</p><p><a href="" id="ch1"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6484549656-1">(</span><span class="ss">ch1</span><span class="p" data-group-id="6484549656-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6484549656-2">(</span><span class="p" data-group-id="6484549656-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6484549656-3">]</span><span class="p" data-group-id="6484549656-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6484549656-4">(</span><span class="p" data-group-id="6484549656-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6484549656-5">]</span><span class="p" data-group-id="6484549656-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6484549656-6">(</span><span class="p" data-group-id="6484549656-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6484549656-7">]</span><span class="p" data-group-id="6484549656-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +respectively.</p><p><a href="" id="ch1"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7369479344-1">(</span><span class="ss">ch1</span><span class="p" data-group-id="7369479344-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7369479344-2">(</span><span class="p" data-group-id="7369479344-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7369479344-3">]</span><span class="p" data-group-id="7369479344-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7369479344-4">(</span><span class="p" data-group-id="7369479344-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7369479344-5">]</span><span class="p" data-group-id="7369479344-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7369479344-6">(</span><span class="p" data-group-id="7369479344-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7369479344-7">]</span><span class="p" data-group-id="7369479344-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="6484549656-8">(</span><span class="p" data-group-id="6484549656-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="6484549656-9">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6484549656-10">[</span><span class="p" data-group-id="6484549656-10">]</span><span class="p" data-group-id="6484549656-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="7369479344-8">(</span><span class="p" data-group-id="7369479344-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7369479344-9">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7369479344-10">[</span><span class="p" data-group-id="7369479344-10">]</span><span class="p" data-group-id="7369479344-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="6484549656-11">(</span><span class="p" data-group-id="6484549656-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6484549656-12">{</span><span class="nf">self</span><span class="p" data-group-id="6484549656-13">(</span><span class="p" data-group-id="6484549656-13">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="6484549656-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="7369479344-11">(</span><span class="p" data-group-id="7369479344-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7369479344-12">{</span><span class="nf">self</span><span class="p" data-group-id="7369479344-13">(</span><span class="p" data-group-id="7369479344-13">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="7369479344-12">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6484549656-14">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="6484549656-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7369479344-14">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="7369479344-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="n">Res</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="6484549656-15">(</span><span class="n">Ch</span><span class="p" data-group-id="6484549656-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6484549656-16">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6484549656-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="7369479344-15">(</span><span class="n">Ch</span><span class="p" data-group-id="7369479344-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7369479344-16">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="7369479344-16">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="6484549656-17">(</span><span class="p" data-group-id="6484549656-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="6484549656-18">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6484549656-19">(</span><span class="p" data-group-id="6484549656-19">)</span><span class="p" data-group-id="6484549656-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="6484549656-20">(</span><span class="p" data-group-id="6484549656-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="6484549656-21">(</span><span class="n">Chs</span><span class="p" data-group-id="6484549656-21">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="7369479344-17">(</span><span class="p" data-group-id="7369479344-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="7369479344-18">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7369479344-19">(</span><span class="p" data-group-id="7369479344-19">)</span><span class="p" data-group-id="7369479344-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="7369479344-20">(</span><span class="p" data-group-id="7369479344-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="7369479344-21">(</span><span class="n">Chs</span><span class="p" data-group-id="7369479344-21">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="6484549656-22">(</span><span class="n">Chs</span><span class="p" data-group-id="6484549656-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="7369479344-22">(</span><span class="n">Chs</span><span class="p" data-group-id="7369479344-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6484549656-23">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="6484549656-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6484549656-24">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="6484549656-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="6484549656-25">(</span><span class="n">Chs</span><span class="p" data-group-id="6484549656-25">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6484549656-26">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6484549656-26">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="6484549656-27">(</span><span class="n">Chs2</span><span class="p" data-group-id="6484549656-27">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6484549656-28">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6484549656-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="6484549656-29">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6484549656-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="6484549656-30">(</span><span class="n">Chs2</span><span class="p" data-group-id="6484549656-30">)</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The code for the server can be rewritten into a generic part <code class="inline">server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3271771598-1">(</span><span class="ss">server</span><span class="p" data-group-id="3271771598-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3271771598-2">(</span><span class="p" data-group-id="3271771598-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3271771598-3">]</span><span class="p" data-group-id="3271771598-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3271771598-4">(</span><span class="p" data-group-id="3271771598-5">[</span><span class="ss">call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3271771598-5">]</span><span class="p" data-group-id="3271771598-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3271771598-6">(</span><span class="p" data-group-id="3271771598-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3271771598-7">]</span><span class="p" data-group-id="3271771598-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7369479344-23">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="7369479344-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="7369479344-24">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="7369479344-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="7369479344-25">(</span><span class="n">Chs</span><span class="p" data-group-id="7369479344-25">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7369479344-26">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="7369479344-26">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="7369479344-27">(</span><span class="n">Chs2</span><span class="p" data-group-id="7369479344-27">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7369479344-28">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="7369479344-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="7369479344-29">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="7369479344-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="7369479344-30">(</span><span class="n">Chs2</span><span class="p" data-group-id="7369479344-30">)</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The code for the server can be rewritten into a generic part <code class="inline">server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7745861797-1">(</span><span class="ss">server</span><span class="p" data-group-id="7745861797-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7745861797-2">(</span><span class="p" data-group-id="7745861797-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7745861797-3">]</span><span class="p" data-group-id="7745861797-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7745861797-4">(</span><span class="p" data-group-id="7745861797-5">[</span><span class="ss">call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7745861797-5">]</span><span class="p" data-group-id="7745861797-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7745861797-6">(</span><span class="p" data-group-id="7745861797-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7745861797-7">]</span><span class="p" data-group-id="7745861797-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="3271771598-8">(</span><span class="n">Mod</span><span class="p" data-group-id="3271771598-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="3271771598-9">(</span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3271771598-10">[</span><span class="n">Mod</span><span class="p" data-group-id="3271771598-10">]</span><span class="p" data-group-id="3271771598-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="7745861797-8">(</span><span class="n">Mod</span><span class="p" data-group-id="7745861797-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7745861797-9">(</span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7745861797-10">[</span><span class="n">Mod</span><span class="p" data-group-id="7745861797-10">]</span><span class="p" data-group-id="7745861797-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">call</span><span class="p" data-group-id="3271771598-11">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="3271771598-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3271771598-12">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3271771598-13">(</span><span class="p" data-group-id="3271771598-13">)</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="3271771598-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">call</span><span class="p" data-group-id="7745861797-11">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="7745861797-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7745861797-12">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7745861797-13">(</span><span class="p" data-group-id="7745861797-13">)</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="7745861797-12">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="3271771598-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="3271771598-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7745861797-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="7745861797-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="n">Res</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">cast</span><span class="p" data-group-id="3271771598-15">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="3271771598-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3271771598-16">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="3271771598-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">cast</span><span class="p" data-group-id="7745861797-15">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="7745861797-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7745861797-16">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="7745861797-16">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3271771598-17">(</span><span class="n">Mod</span><span class="p" data-group-id="3271771598-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="3271771598-18">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3271771598-19">(</span><span class="p" data-group-id="3271771598-19">)</span><span class="p" data-group-id="3271771598-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">init</span><span class="p" data-group-id="3271771598-20">(</span><span class="p" data-group-id="3271771598-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="3271771598-21">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3271771598-21">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="7745861797-17">(</span><span class="n">Mod</span><span class="p" data-group-id="7745861797-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="7745861797-18">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7745861797-19">(</span><span class="p" data-group-id="7745861797-19">)</span><span class="p" data-group-id="7745861797-18">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">init</span><span class="p" data-group-id="7745861797-20">(</span><span class="p" data-group-id="7745861797-20">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="7745861797-21">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7745861797-21">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="3271771598-22">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3271771598-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="7745861797-22">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7745861797-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="3271771598-23">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="3271771598-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="3271771598-24">{</span><span class="n">Res</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="3271771598-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_call</span><span class="p" data-group-id="3271771598-25">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3271771598-25">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3271771598-26">{</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="3271771598-26">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="3271771598-27">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="3271771598-27">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="3271771598-28">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="3271771598-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">State2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_cast</span><span class="p" data-group-id="3271771598-29">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3271771598-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="3271771598-30">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="3271771598-30">)</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>And a callback module <code class="inline">ch2.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9842782954-1">(</span><span class="ss">ch2</span><span class="p" data-group-id="9842782954-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9842782954-2">(</span><span class="p" data-group-id="9842782954-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9842782954-3">]</span><span class="p" data-group-id="9842782954-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9842782954-4">(</span><span class="p" data-group-id="9842782954-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9842782954-5">]</span><span class="p" data-group-id="9842782954-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9842782954-6">(</span><span class="p" data-group-id="9842782954-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9842782954-7">]</span><span class="p" data-group-id="9842782954-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="9842782954-8">(</span><span class="p" data-group-id="9842782954-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9842782954-9">(</span><span class="ss">ch2</span><span class="p" data-group-id="9842782954-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="9842782954-10">(</span><span class="p" data-group-id="9842782954-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="9842782954-11">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="9842782954-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="9842782954-12">(</span><span class="n">Ch</span><span class="p" data-group-id="9842782954-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="9842782954-13">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9842782954-14">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="9842782954-14">}</span><span class="p" data-group-id="9842782954-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7745861797-23">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="7745861797-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="7745861797-24">{</span><span class="n">Res</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="7745861797-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_call</span><span class="p" data-group-id="7745861797-25">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7745861797-25">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7745861797-26">{</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="7745861797-26">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="7745861797-27">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="7745861797-27">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="7745861797-28">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="7745861797-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">State2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_cast</span><span class="p" data-group-id="7745861797-29">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7745861797-29">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="7745861797-30">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="7745861797-30">)</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>And a callback module <code class="inline">ch2.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6753345746-1">(</span><span class="ss">ch2</span><span class="p" data-group-id="6753345746-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6753345746-2">(</span><span class="p" data-group-id="6753345746-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6753345746-3">]</span><span class="p" data-group-id="6753345746-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6753345746-4">(</span><span class="p" data-group-id="6753345746-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6753345746-5">]</span><span class="p" data-group-id="6753345746-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6753345746-6">(</span><span class="p" data-group-id="6753345746-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6753345746-7">]</span><span class="p" data-group-id="6753345746-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="6753345746-8">(</span><span class="p" data-group-id="6753345746-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="6753345746-9">(</span><span class="ss">ch2</span><span class="p" data-group-id="6753345746-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="6753345746-10">(</span><span class="p" data-group-id="6753345746-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="6753345746-11">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="6753345746-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="6753345746-12">(</span><span class="n">Ch</span><span class="p" data-group-id="6753345746-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="6753345746-13">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6753345746-14">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6753345746-14">}</span><span class="p" data-group-id="6753345746-13">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="9842782954-15">(</span><span class="p" data-group-id="9842782954-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">channels</span><span class="p" data-group-id="9842782954-16">(</span><span class="p" data-group-id="9842782954-16">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="6753345746-15">(</span><span class="p" data-group-id="6753345746-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">channels</span><span class="p" data-group-id="6753345746-16">(</span><span class="p" data-group-id="6753345746-16">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="9842782954-17">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="9842782954-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">alloc</span><span class="p" data-group-id="9842782954-18">(</span><span class="n">Chs</span><span class="p" data-group-id="9842782954-18">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; {Ch,Chs2}</span><span class="w">
│ │ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="6753345746-17">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6753345746-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">alloc</span><span class="p" data-group-id="6753345746-18">(</span><span class="n">Chs</span><span class="p" data-group-id="6753345746-18">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; {Ch,Chs2}</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="9842782954-19">(</span><span class="p" data-group-id="9842782954-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="9842782954-20">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="9842782954-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">free</span><span class="p" data-group-id="9842782954-21">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="9842782954-21">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; Chs2</span></code></pre><p>Notice the following:</p><ul><li>The code in <code class="inline">server</code> can be reused to build many different servers.</li><li>The server name, in this example the atom <code class="inline">ch2</code>, is hidden from the users of
│ │ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="6753345746-19">(</span><span class="p" data-group-id="6753345746-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6753345746-20">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6753345746-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">free</span><span class="p" data-group-id="6753345746-21">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="6753345746-21">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; Chs2</span></code></pre><p>Notice the following:</p><ul><li>The code in <code class="inline">server</code> can be reused to build many different servers.</li><li>The server name, in this example the atom <code class="inline">ch2</code>, is hidden from the users of
│ │ │ │  the client functions. This means that the name can be changed without
│ │ │ │  affecting them.</li><li>The protocol (messages sent to and received from the server) is also hidden.
│ │ │ │  This is good programming practice and allows one to change the protocol
│ │ │ │  without changing the code using the interface functions.</li><li>The functionality of <code class="inline">server</code> can be extended without having to change <code class="inline">ch2</code>
│ │ │ │  or any other callback module.</li></ul><p>In <code class="inline">ch1.erl</code> and <code class="inline">ch2.erl</code> above, the implementation of <code class="inline">channels/0</code>, <code class="inline">alloc/1</code>,
│ │ │ │  and <code class="inline">free/2</code> has been intentionally left out, as it is not relevant to the
│ │ │ │  example. For completeness, one way to write these functions is given below. This
│ │ │ │  is an example only, a realistic implementation must be able to handle situations
│ │ │ │ -like running out of channels to allocate, and so on.</p><p><a href="" id="channels-implementation"></a></p><pre><code class="makeup erlang" translate="no"><span class="nf">channels</span><span class="p" data-group-id="2497929116-1">(</span><span class="p" data-group-id="2497929116-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="2497929116-2">{</span><span class="p">_</span><span class="n">Allocated</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2497929116-3">[</span><span class="p" data-group-id="2497929116-3">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2497929116-4">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="2497929116-4">)</span><span class="p" data-group-id="2497929116-2">}</span><span class="p">.</span><span class="w">
│ │ │ │ +like running out of channels to allocate, and so on.</p><p><a href="" id="channels-implementation"></a></p><pre><code class="makeup erlang" translate="no"><span class="nf">channels</span><span class="p" data-group-id="9184284663-1">(</span><span class="p" data-group-id="9184284663-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="9184284663-2">{</span><span class="p">_</span><span class="n">Allocated</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9184284663-3">[</span><span class="p" data-group-id="9184284663-3">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9184284663-4">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="9184284663-4">)</span><span class="p" data-group-id="9184284663-2">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="2497929116-5">(</span><span class="p" data-group-id="2497929116-6">{</span><span class="n">Allocated</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2497929116-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2497929116-7">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="p" data-group-id="2497929116-6">}</span><span class="p" data-group-id="2497929116-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="2497929116-8">{</span><span class="n">H</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2497929116-9">{</span><span class="p" data-group-id="2497929116-10">[</span><span class="n">H</span><span class="p">|</span><span class="n">Allocated</span><span class="p" data-group-id="2497929116-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="2497929116-9">}</span><span class="p" data-group-id="2497929116-8">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="9184284663-5">(</span><span class="p" data-group-id="9184284663-6">{</span><span class="n">Allocated</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184284663-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9184284663-7">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="p" data-group-id="9184284663-6">}</span><span class="p" data-group-id="9184284663-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="9184284663-8">{</span><span class="n">H</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184284663-9">{</span><span class="p" data-group-id="9184284663-10">[</span><span class="n">H</span><span class="p">|</span><span class="n">Allocated</span><span class="p" data-group-id="9184284663-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9184284663-9">}</span><span class="p" data-group-id="9184284663-8">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="2497929116-11">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2497929116-12">{</span><span class="n">Alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Free</span><span class="p" data-group-id="2497929116-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Channels</span><span class="p" data-group-id="2497929116-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="2497929116-13">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="2497929116-13">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="9184284663-11">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184284663-12">{</span><span class="n">Alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Free</span><span class="p" data-group-id="9184284663-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Channels</span><span class="p" data-group-id="9184284663-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="9184284663-13">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="9184284663-13">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │        </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -         </span><span class="p" data-group-id="2497929116-14">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="2497929116-15">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="2497929116-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2497929116-16">[</span><span class="n">Ch</span><span class="p">|</span><span class="n">Free</span><span class="p" data-group-id="2497929116-16">]</span><span class="p" data-group-id="2497929116-14">}</span><span class="p">;</span><span class="w">
│ │ │ │ +         </span><span class="p" data-group-id="9184284663-14">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="9184284663-15">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="9184284663-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184284663-16">[</span><span class="n">Ch</span><span class="p">|</span><span class="n">Free</span><span class="p" data-group-id="9184284663-16">]</span><span class="p" data-group-id="9184284663-14">}</span><span class="p">;</span><span class="w">
│ │ │ │        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │           </span><span class="n">Channels</span><span class="w">
│ │ │ │     </span><span class="k">end</span><span class="p">.</span></code></pre><p>Code written without using behaviours can be more efficient, but the increased
│ │ │ │  efficiency is at the expense of generality. The ability to manage all
│ │ │ │  applications in the system in a consistent manner is important.</p><p>Using behaviours also makes it easier to read and understand code written by
│ │ │ │  other programmers. Improvised programming structures, while possibly more
│ │ │ │  efficient, are always more difficult to understand.</p><p>The <code class="inline">server</code> module corresponds, greatly simplified, to the Erlang/OTP behaviour
│ │ │ │  <code class="inline">gen_server</code>.</p><p>The standard Erlang/OTP behaviours are:</p><ul><li><p><a href="gen_server_concepts.xhtml">gen_server</a></p><p>For implementing the server of a client-server relation</p></li><li><p><a href="statem.xhtml">gen_statem</a></p><p>For implementing state machines</p></li><li><p><a href="events.xhtml">gen_event</a></p><p>For implementing event handling functionality</p></li><li><p><a href="sup_princ.xhtml">supervisor</a></p><p>For implementing a supervisor in a supervision tree</p></li></ul><p>The compiler understands the module attribute <code class="inline">-behaviour(Behaviour)</code> and issues
│ │ │ │ -warnings about missing callback functions, for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5902512071-1">(</span><span class="ss">chs3</span><span class="p" data-group-id="5902512071-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5902512071-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="5902512071-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +warnings about missing callback functions, for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4853575312-1">(</span><span class="ss">chs3</span><span class="p" data-group-id="4853575312-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="4853575312-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="4853575312-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="5902512071-3">(</span><span class="ss">chs3</span><span class="p" data-group-id="5902512071-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="4853575312-3">(</span><span class="ss">chs3</span><span class="p" data-group-id="4853575312-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="o">/</span><span class="ss">chs3</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">10</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="ss">undefined</span><span class="w"> </span><span class="ss">call</span><span class="o">-</span><span class="ss">back</span><span class="w"> </span><span class="ss">function</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5902512071-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">chs3</span><span class="p" data-group-id="5902512071-4">}</span></code></pre><h2 id="applications" class="section-heading">
│ │ │ │ +</span><span class="p" data-group-id="4853575312-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">chs3</span><span class="p" data-group-id="4853575312-4">}</span></code></pre><h2 id="applications" class="section-heading">
│ │ │ │    <a href="#applications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Applications</span>
│ │ │ │  </h2>
│ │ │ │  <p>Erlang/OTP comes with a number of components, each implementing some specific
│ │ │ │  functionality. Components are with Erlang/OTP terminology called <em>applications</em>.
│ │ │ ├── OEBPS/data_types.xhtml
│ │ │ │ @@ -97,18 +97,18 @@
│ │ │ │    </a>
│ │ │ │    <span class="text">Representation of Floating Point Numbers</span>
│ │ │ │  </h3>
│ │ │ │  <p>When working with floats you may not see what you expect when printing or doing
│ │ │ │  arithmetic operations. This is because floats are represented by a fixed number
│ │ │ │  of bits in a base-2 system while printed floats are represented with a base-10
│ │ │ │  system. Erlang uses 64-bit floats. Here are examples of this phenomenon:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="mf">0.30000000000000004</span></code></pre><p>The real numbers <code class="inline">0.1</code> and <code class="inline">0.2</code> cannot be represented exactly as floats.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0264791248-1">{</span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963968</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="mf">36028797018963970.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963970</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963970.0</span><span class="p" data-group-id="0264791248-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0264791248-2">{</span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="0264791248-2">}</span><span class="p">.</span></code></pre><p>The value <code class="inline">36028797018963968</code> can be represented exactly as a float value but
│ │ │ │ +</span><span class="mf">0.30000000000000004</span></code></pre><p>The real numbers <code class="inline">0.1</code> and <code class="inline">0.2</code> cannot be represented exactly as floats.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5856570785-1">{</span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963968</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="mf">36028797018963970.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963970</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963970.0</span><span class="p" data-group-id="5856570785-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5856570785-2">{</span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="5856570785-2">}</span><span class="p">.</span></code></pre><p>The value <code class="inline">36028797018963968</code> can be represented exactly as a float value but
│ │ │ │  Erlang's pretty printer rounds <code class="inline">36028797018963968.0</code> to <code class="inline">3.602879701896397e16</code>
│ │ │ │  (<code class="inline">=36028797018963970.0</code>) as all values in the range
│ │ │ │  <code class="inline">[36028797018963966.0, 36028797018963972.0]</code> are represented by
│ │ │ │  <code class="inline">36028797018963968.0</code>.</p><p>For more information about floats and issues with them see:</p><ul><li><a href="https://floating-point-gui.de/">What Every Programmer Should Know About Floating-Point Arithmetic</a></li><li><a href="https://0.30000000000000004.com/">0.30000000000000004.com/</a></li><li><a href="https://docs.python.org/3/tutorial/floatingpoint.html">Floating Point Arithmetic: Issues and Limitations</a></li></ul><p>If you need to work with exact decimal fractions, for instance to represent
│ │ │ │  money, it is recommended to use a library that handles that, or work in
│ │ │ │  cents instead of dollars or euros so that decimal fractions are not needed.</p><p>Also note that Erlang's floats do not exactly match IEEE 754 floats,
│ │ │ │  in that neither <em>Inf</em> nor <em>NaN</em> are supported in Erlang. Any
│ │ │ │ @@ -142,52 +142,52 @@
│ │ │ │  by eight are called <em>binaries</em>.</p><p><em>Examples:</em></p><pre><code class="text">1&gt; &lt;&lt;10,20&gt;&gt;.
│ │ │ │  &lt;&lt;10,20&gt;&gt;
│ │ │ │  2&gt; &lt;&lt;&quot;ABC&quot;&gt;&gt;.
│ │ │ │  &lt;&lt;&quot;ABC&quot;&gt;&gt;
│ │ │ │  3&gt; &lt;&lt;1:1,0:1&gt;&gt;.
│ │ │ │  &lt;&lt;2:2&gt;&gt;</code></pre><p>The <a href="../../../lib/../erts/doc/html/erlang.html#is_bitstring/1"><code class="inline">is_bitstring/1</code></a> BIF tests whether a
│ │ │ │  term is a bit string, and the <a href="../../../lib/../erts/doc/html/erlang.html#is_binary/1"><code class="inline">is_binary/1</code></a>
│ │ │ │ -BIF tests whether a term is a binary.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">is_bitstring</span><span class="p" data-group-id="3503917891-1">(</span><span class="p" data-group-id="3503917891-2">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3503917891-2">&gt;&gt;</span><span class="p" data-group-id="3503917891-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +BIF tests whether a term is a binary.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">is_bitstring</span><span class="p" data-group-id="5471709959-1">(</span><span class="p" data-group-id="5471709959-2">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="5471709959-2">&gt;&gt;</span><span class="p" data-group-id="5471709959-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="3503917891-3">(</span><span class="p" data-group-id="3503917891-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3503917891-4">&gt;&gt;</span><span class="p" data-group-id="3503917891-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="5471709959-3">(</span><span class="p" data-group-id="5471709959-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="5471709959-4">&gt;&gt;</span><span class="p" data-group-id="5471709959-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="3503917891-5">(</span><span class="p" data-group-id="3503917891-6">&lt;&lt;</span><span class="mi">42</span><span class="p" data-group-id="3503917891-6">&gt;&gt;</span><span class="p" data-group-id="3503917891-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="5471709959-5">(</span><span class="p" data-group-id="5471709959-6">&lt;&lt;</span><span class="mi">42</span><span class="p" data-group-id="5471709959-6">&gt;&gt;</span><span class="p" data-group-id="5471709959-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="w">
│ │ │ │  </span></code></pre><p>For more examples, see <a href="../../../lib/../system/doc/html/bit_syntax.xhtml">Programming Examples</a>.</p><h2 id="reference" class="section-heading">
│ │ │ │    <a href="#reference" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Reference</span>
│ │ │ │  </h2>
│ │ │ │  <p>A term that is <a href="../../../lib/../system/doc/html/system_limits.xhtml#unique_references">unique</a>
│ │ │ │  among connected nodes. A reference is created by calling the
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#make_ref/0"><code class="inline">make_ref/0</code></a> BIF. The
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#is_reference/1"><code class="inline">is_reference/1</code></a> BIF tests whether a term
│ │ │ │ -is a reference.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="2749745612-1">(</span><span class="p" data-group-id="2749745612-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +is a reference.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="9144173869-1">(</span><span class="p" data-group-id="9144173869-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Ref</span><span class="o">&lt;</span><span class="mf">0.76482849</span><span class="p">.</span><span class="mf">3801088007.198204</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nf">is_reference</span><span class="p" data-group-id="2749745612-2">(</span><span class="n">Ref</span><span class="p" data-group-id="2749745612-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nf">is_reference</span><span class="p" data-group-id="9144173869-2">(</span><span class="n">Ref</span><span class="p" data-group-id="9144173869-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span></code></pre><h2 id="fun" class="section-heading">
│ │ │ │    <a href="#fun" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Fun</span>
│ │ │ │  </h2>
│ │ │ │  <p>A fun is a functional object. Funs make it possible to create an anonymous
│ │ │ │  function and pass the function itself — not its name — as argument to other
│ │ │ │ -functions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="1224591374-1">(</span><span class="n">X</span><span class="p" data-group-id="1224591374-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +functions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3778786006-1">(</span><span class="n">X</span><span class="p" data-group-id="3778786006-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="1224591374-2">(</span><span class="mi">2</span><span class="p" data-group-id="1224591374-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="3778786006-2">(</span><span class="mi">2</span><span class="p" data-group-id="3778786006-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span></code></pre><p>The <a href="../../../lib/../erts/doc/html/erlang.html#is_function/1"><code class="inline">is_function/1</code></a> and <a href="../../../lib/../erts/doc/html/erlang.html#is_function/2"><code class="inline">is_function/2</code></a>
│ │ │ │ -BIFs tests whether a term is a fun.</p><p><em>Examples</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4956028736-1">(</span><span class="p" data-group-id="4956028736-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │ +BIFs tests whether a term is a fun.</p><p><em>Examples</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1622535046-1">(</span><span class="p" data-group-id="1622535046-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">43.105768164</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4956028736-2">(</span><span class="n">F</span><span class="p" data-group-id="4956028736-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="1622535046-2">(</span><span class="n">F</span><span class="p" data-group-id="1622535046-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4956028736-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4956028736-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="1622535046-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="1622535046-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4956028736-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4956028736-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="1622535046-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="1622535046-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span></code></pre><p>Read more about funs in <a href="expressions.xhtml#fun-expressions">Fun Expressions</a>. For more
│ │ │ │  examples, see <a href="../../../lib/../system/doc/html/funs.xhtml">Programming Examples</a>.</p><h2 id="port-identifier" class="section-heading">
│ │ │ │    <a href="#port-identifier" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Port Identifier</span>
│ │ │ │  </h2>
│ │ │ │ @@ -205,94 +205,94 @@
│ │ │ │  for a new process after a while.</p><p>The BIF <a href="../../../lib/../erts/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a> returns the Pid of the calling process. When
│ │ │ │  <a href="ref_man_processes.xhtml#process-creation">creating a new process</a>, the parent
│ │ │ │  process will be able to get the Pid of the child process either via the return
│ │ │ │  value, as is the case when calling the <a href="../../../lib/../erts/doc/html/erlang.html#spawn/3"><code class="inline">spawn/3</code></a> BIF, or via
│ │ │ │  a message, which is the case when calling the
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#spawn_request/5"><code class="inline">spawn_request/5</code></a> BIF. A Pid is typically used when
│ │ │ │  when sending a process a <a href="ref_man_processes.xhtml#signals">signal</a>. The
│ │ │ │ -<a href="../../../lib/../erts/doc/html/erlang.html#is_pid/1"><code class="inline">is_pid/1</code></a> BIF tests whether a term is a Pid.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4013525220-1">(</span><span class="ss">m</span><span class="p" data-group-id="4013525220-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4013525220-2">(</span><span class="p" data-group-id="4013525220-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="4013525220-3">]</span><span class="p" data-group-id="4013525220-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<a href="../../../lib/../erts/doc/html/erlang.html#is_pid/1"><code class="inline">is_pid/1</code></a> BIF tests whether a term is a Pid.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7275814797-1">(</span><span class="ss">m</span><span class="p" data-group-id="7275814797-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7275814797-2">(</span><span class="p" data-group-id="7275814797-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7275814797-3">]</span><span class="p" data-group-id="7275814797-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="4013525220-4">(</span><span class="p" data-group-id="4013525220-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="7275814797-4">(</span><span class="p" data-group-id="7275814797-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">who_are_you</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4013525220-5">(</span><span class="s">&quot;I am </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4013525220-6">[</span><span class="nf">self</span><span class="p" data-group-id="4013525220-7">(</span><span class="p" data-group-id="4013525220-7">)</span><span class="p" data-group-id="4013525220-6">]</span><span class="p" data-group-id="4013525220-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="4013525220-8">(</span><span class="p" data-group-id="4013525220-8">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7275814797-5">(</span><span class="s">&quot;I am </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7275814797-6">[</span><span class="nf">self</span><span class="p" data-group-id="7275814797-7">(</span><span class="p" data-group-id="7275814797-7">)</span><span class="p" data-group-id="7275814797-6">]</span><span class="p" data-group-id="7275814797-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="7275814797-8">(</span><span class="p" data-group-id="7275814797-8">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="4013525220-9">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">loop</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4013525220-10">[</span><span class="p" data-group-id="4013525220-10">]</span><span class="p" data-group-id="4013525220-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="7275814797-9">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">loop</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7275814797-10">[</span><span class="p" data-group-id="7275814797-10">]</span><span class="p" data-group-id="7275814797-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.58</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │  2&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">who_are_you</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="n">I</span><span class="w"> </span><span class="ss">am</span><span class="w"> </span><span class="o">&lt;</span><span class="mf">0.58</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ │  </span><span class="ss">who_are_you</span></code></pre><p>Read more about processes in <a href="ref_man_processes.xhtml">Processes</a>.</p><h2 id="tuple" class="section-heading">
│ │ │ │    <a href="#tuple" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Tuple</span>
│ │ │ │  </h2>
│ │ │ │  <p>A tuple is a compound data type with a fixed number of terms:</p><pre><code class="text">{Term1,...,TermN}</code></pre><p>Each term <code class="inline">Term</code> in the tuple is called an <em>element</em>. The number of elements is
│ │ │ │ -said to be the <em>size</em> of the tuple.</p><p>There exists a number of BIFs to manipulate tuples.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8813455577-1">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="8813455577-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8813455577-2">}</span><span class="p" data-group-id="8813455577-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8813455577-3">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="8813455577-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8813455577-4">}</span><span class="p" data-group-id="8813455577-3">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nf">element</span><span class="p" data-group-id="8813455577-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="8813455577-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +said to be the <em>size</em> of the tuple.</p><p>There exists a number of BIFs to manipulate tuples.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2277644174-1">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="2277644174-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2277644174-2">}</span><span class="p" data-group-id="2277644174-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2277644174-3">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="2277644174-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2277644174-4">}</span><span class="p" data-group-id="2277644174-3">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nf">element</span><span class="p" data-group-id="2277644174-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="2277644174-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">adam</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nf">element</span><span class="p" data-group-id="8813455577-6">(</span><span class="mi">3</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="8813455577-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8813455577-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8813455577-7">}</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="8813455577-8">(</span><span class="mi">2</span><span class="p">,</span><span class="n">P</span><span class="p">,</span><span class="mi">25</span><span class="p" data-group-id="8813455577-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8813455577-9">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">25</span><span class="p">,</span><span class="p" data-group-id="8813455577-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8813455577-10">}</span><span class="p" data-group-id="8813455577-9">}</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="8813455577-11">(</span><span class="n">P</span><span class="p" data-group-id="8813455577-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nf">element</span><span class="p" data-group-id="2277644174-6">(</span><span class="mi">3</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="2277644174-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2277644174-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2277644174-7">}</span><span class="gp unselectable">
│ │ │ │ +4&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="2277644174-8">(</span><span class="mi">2</span><span class="p">,</span><span class="n">P</span><span class="p">,</span><span class="mi">25</span><span class="p" data-group-id="2277644174-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2277644174-9">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">25</span><span class="p">,</span><span class="p" data-group-id="2277644174-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2277644174-10">}</span><span class="p" data-group-id="2277644174-9">}</span><span class="gp unselectable">
│ │ │ │ +5&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="2277644174-11">(</span><span class="n">P</span><span class="p" data-group-id="2277644174-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="8813455577-12">(</span><span class="p" data-group-id="8813455577-13">{</span><span class="p" data-group-id="8813455577-13">}</span><span class="p" data-group-id="8813455577-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="2277644174-12">(</span><span class="p" data-group-id="2277644174-13">{</span><span class="p" data-group-id="2277644174-13">}</span><span class="p" data-group-id="2277644174-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">0</span><span class="gp unselectable">
│ │ │ │ -7&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="8813455577-14">(</span><span class="p" data-group-id="8813455577-15">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8813455577-15">}</span><span class="p" data-group-id="8813455577-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +7&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="2277644174-14">(</span><span class="p" data-group-id="2277644174-15">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="2277644174-15">}</span><span class="p" data-group-id="2277644174-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span></code></pre><h2 id="map" class="section-heading">
│ │ │ │    <a href="#map" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Map</span>
│ │ │ │  </h2>
│ │ │ │  <p>A map is a compound data type with a variable number of key-value associations:</p><pre><code class="text">#{Key1 =&gt; Value1, ..., KeyN =&gt; ValueN}</code></pre><p>Each key-value association in the map is called an <em>association pair</em>. The key
│ │ │ │  and value parts of the pair are called <em>elements</em>. The number of association
│ │ │ │ -pairs is said to be the <em>size</em> of the map.</p><p>There exists a number of BIFs to manipulate maps.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2367345898-1">#{</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="w"> </span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2367345898-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2367345898-2">}</span><span class="p" data-group-id="2367345898-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2367345898-3">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2367345898-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2367345898-4">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="2367345898-3">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="2367345898-5">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="2367345898-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +pairs is said to be the <em>size</em> of the map.</p><p>There exists a number of BIFs to manipulate maps.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8431089842-1">#{</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="w"> </span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8431089842-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8431089842-2">}</span><span class="p" data-group-id="8431089842-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8431089842-3">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8431089842-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8431089842-4">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="8431089842-3">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="8431089842-5">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="8431089842-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">adam</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="2367345898-6">(</span><span class="ss">date</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="2367345898-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2367345898-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2367345898-7">}</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="2367345898-8">(</span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="2367345898-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2367345898-9">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2367345898-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="2367345898-10">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="2367345898-9">}</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="2367345898-11">(</span><span class="n">M</span><span class="p" data-group-id="2367345898-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="8431089842-6">(</span><span class="ss">date</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="8431089842-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8431089842-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8431089842-7">}</span><span class="gp unselectable">
│ │ │ │ +4&gt; </span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="8431089842-8">(</span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="8431089842-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8431089842-9">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8431089842-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="8431089842-10">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="8431089842-9">}</span><span class="gp unselectable">
│ │ │ │ +5&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="8431089842-11">(</span><span class="n">M</span><span class="p" data-group-id="8431089842-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="2367345898-12">(</span><span class="p" data-group-id="2367345898-13">#{</span><span class="p" data-group-id="2367345898-13">}</span><span class="p" data-group-id="2367345898-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +6&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="8431089842-12">(</span><span class="p" data-group-id="8431089842-13">#{</span><span class="p" data-group-id="8431089842-13">}</span><span class="p" data-group-id="8431089842-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">0</span></code></pre><p>A collection of maps processing functions are found in module <a href="../../../lib/stdlib/doc/html/maps.html"><code class="inline">maps</code></a>
│ │ │ │  in STDLIB.</p><p>Read more about maps in <a href="expressions.xhtml#map-expressions">Map Expressions</a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Maps were introduced as an experimental feature in Erlang/OTP R17. Their
│ │ │ │  functionality was extended and became fully supported in Erlang/OTP 18.</p></section><h2 id="list" class="section-heading">
│ │ │ │    <a href="#list" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">List</span>
│ │ │ │  </h2>
│ │ │ │  <p>A list is a compound data type with a variable number of terms.</p><pre><code class="text">[Term1,...,TermN]</code></pre><p>Each term <code class="inline">Term</code> in the list is called an <em>element</em>. The number of elements is
│ │ │ │  said to be the <em>length</em> of the list.</p><p>Formally, a list is either the empty list <code class="inline">[]</code> or consists of a <em>head</em> (first
│ │ │ │  element) and a <em>tail</em> (remainder of the list). The <em>tail</em> is also a list. The
│ │ │ │  latter can be expressed as <code class="inline">[H|T]</code>. The notation <code class="inline">[Term1,...,TermN]</code> above is
│ │ │ │  equivalent with the list <code class="inline">[Term1|[...|[TermN|[]]]]</code>.</p><p><em>Example:</em></p><p><code class="inline">[]</code> is a list, thus<br/><code class="inline">[c|[]]</code> is a list, thus<br/><code class="inline">[b|[c|[]]]</code> is a list, thus<br/><code class="inline">[a|[b|[c|[]]]]</code> is a list, or in short <code class="inline">[a,b,c]</code></p><p>A list where the tail is a list is sometimes called a <em>proper list</em>. It is
│ │ │ │  allowed to have a list where the tail is not a list, for example, <code class="inline">[a|b]</code>.
│ │ │ │ -However, this type of list is of little practical use.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6244947329-1">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6244947329-2">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6244947329-2">}</span><span class="p" data-group-id="6244947329-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6244947329-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6244947329-4">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6244947329-4">}</span><span class="p" data-group-id="6244947329-3">]</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="p" data-group-id="6244947329-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6244947329-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L1</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6244947329-6">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6244947329-7">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6244947329-7">}</span><span class="p" data-group-id="6244947329-6">]</span><span class="gp unselectable">
│ │ │ │ +However, this type of list is of little practical use.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1618423481-1">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="1618423481-2">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="1618423481-2">}</span><span class="p" data-group-id="1618423481-1">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1618423481-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="1618423481-4">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="1618423481-4">}</span><span class="p" data-group-id="1618423481-3">]</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="p" data-group-id="1618423481-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1618423481-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L1</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1618423481-6">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="1618423481-7">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="1618423481-7">}</span><span class="p" data-group-id="1618423481-6">]</span><span class="gp unselectable">
│ │ │ │  3&gt; </span><span class="n">H</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">a</span><span class="gp unselectable">
│ │ │ │  4&gt; </span><span class="n">T</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6244947329-8">[</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6244947329-9">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6244947329-9">}</span><span class="p" data-group-id="6244947329-8">]</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="n">L2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6244947329-10">[</span><span class="ss">d</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6244947329-10">]</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6244947329-11">[</span><span class="ss">d</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6244947329-12">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6244947329-12">}</span><span class="p" data-group-id="6244947329-11">]</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nf">length</span><span class="p" data-group-id="6244947329-13">(</span><span class="n">L1</span><span class="p" data-group-id="6244947329-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1618423481-8">[</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="1618423481-9">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="1618423481-9">}</span><span class="p" data-group-id="1618423481-8">]</span><span class="gp unselectable">
│ │ │ │ +5&gt; </span><span class="n">L2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1618423481-10">[</span><span class="ss">d</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1618423481-10">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1618423481-11">[</span><span class="ss">d</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="1618423481-12">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="1618423481-12">}</span><span class="p" data-group-id="1618423481-11">]</span><span class="gp unselectable">
│ │ │ │ +6&gt; </span><span class="nf">length</span><span class="p" data-group-id="1618423481-13">(</span><span class="n">L1</span><span class="p" data-group-id="1618423481-13">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ │ -7&gt; </span><span class="nf">length</span><span class="p" data-group-id="6244947329-14">(</span><span class="p" data-group-id="6244947329-15">[</span><span class="p" data-group-id="6244947329-15">]</span><span class="p" data-group-id="6244947329-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +7&gt; </span><span class="nf">length</span><span class="p" data-group-id="1618423481-14">(</span><span class="p" data-group-id="1618423481-15">[</span><span class="p" data-group-id="1618423481-15">]</span><span class="p" data-group-id="1618423481-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">0</span></code></pre><p>A collection of list processing functions are found in module
│ │ │ │  <a href="../../../lib/stdlib/doc/html/lists.html"><code class="inline">lists</code></a> in STDLIB.</p><h2 id="string" class="section-heading">
│ │ │ │    <a href="#string" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">String</span>
│ │ │ │  </h2>
│ │ │ │ @@ -412,41 +412,41 @@
│ │ │ │    <span class="text">Record</span>
│ │ │ │  </h2>
│ │ │ │  <p>A record is a data structure for storing a fixed number of elements. It has
│ │ │ │  named fields and is similar to a struct in C. However, a record is not a true
│ │ │ │  data type. Instead, record expressions are translated to tuple expressions
│ │ │ │  during compilation. Therefore, record expressions are not understood by the
│ │ │ │  shell unless special actions are taken. For details, see module <a href="../../../lib/stdlib/doc/html/shell.html"><code class="inline">shell</code></a>
│ │ │ │ -in STDLIB.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1512040615-1">(</span><span class="ss">person</span><span class="p" data-group-id="1512040615-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1512040615-2">(</span><span class="p" data-group-id="1512040615-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1512040615-3">]</span><span class="p" data-group-id="1512040615-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +in STDLIB.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5836243479-1">(</span><span class="ss">person</span><span class="p" data-group-id="5836243479-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5836243479-2">(</span><span class="p" data-group-id="5836243479-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5836243479-3">]</span><span class="p" data-group-id="5836243479-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1512040615-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512040615-5">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="1512040615-5">}</span><span class="p" data-group-id="1512040615-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5836243479-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5836243479-5">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="5836243479-5">}</span><span class="p" data-group-id="5836243479-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">new</span><span class="p" data-group-id="1512040615-6">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="1512040615-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1512040615-7">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="o">=</span><span class="n">Age</span><span class="p" data-group-id="1512040615-7">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">new</span><span class="p" data-group-id="5836243479-6">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="5836243479-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5836243479-7">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="o">=</span><span class="n">Age</span><span class="p" data-group-id="5836243479-7">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">person</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="1512040615-8">(</span><span class="ss">ernie</span><span class="p">,</span><span class="w"> </span><span class="mi">44</span><span class="p" data-group-id="1512040615-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1512040615-9">{</span><span class="ss">person</span><span class="p">,</span><span class="ss">ernie</span><span class="p">,</span><span class="mi">44</span><span class="p" data-group-id="1512040615-9">}</span></code></pre><p>Read more about records in <a href="ref_man_records.xhtml">Records</a>. More examples are
│ │ │ │ +</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">person</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="5836243479-8">(</span><span class="ss">ernie</span><span class="p">,</span><span class="w"> </span><span class="mi">44</span><span class="p" data-group-id="5836243479-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5836243479-9">{</span><span class="ss">person</span><span class="p">,</span><span class="ss">ernie</span><span class="p">,</span><span class="mi">44</span><span class="p" data-group-id="5836243479-9">}</span></code></pre><p>Read more about records in <a href="ref_man_records.xhtml">Records</a>. More examples are
│ │ │ │  found in <a href="../../../lib/../system/doc/html/prog_ex_records.xhtml">Programming Examples</a>.</p><h2 id="boolean" class="section-heading">
│ │ │ │    <a href="#boolean" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Boolean</span>
│ │ │ │  </h2>
│ │ │ │  <p>There is no Boolean data type in Erlang. Instead the atoms <code class="inline">true</code> and <code class="inline">false</code>
│ │ │ │  are used to denote Boolean values. The <a href="../../../lib/../erts/doc/html/erlang.html#is_boolean/1"><code class="inline">is_boolean/1</code></a>
│ │ │ │  BIF tests whether a term is a boolean.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="mi">2</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │  2&gt; </span><span class="ss">true</span><span class="w"> </span><span class="ow">or</span><span class="w"> </span><span class="ss">false</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="2053244451-1">(</span><span class="ss">true</span><span class="p" data-group-id="2053244451-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="6308372555-1">(</span><span class="ss">true</span><span class="p" data-group-id="6308372555-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="2053244451-2">(</span><span class="ss">false</span><span class="p" data-group-id="2053244451-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="6308372555-2">(</span><span class="ss">false</span><span class="p" data-group-id="6308372555-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="2053244451-3">(</span><span class="ss">ok</span><span class="p" data-group-id="2053244451-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="6308372555-3">(</span><span class="ss">ok</span><span class="p" data-group-id="6308372555-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span></code></pre><h2 id="escape-sequences" class="section-heading">
│ │ │ │    <a href="#escape-sequences" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Escape Sequences</span>
│ │ │ │  </h2>
│ │ │ │  <p>Within strings (<code class="inline">&quot;</code>-delimited), quoted atoms, and the content of
│ │ │ │ @@ -464,44 +464,44 @@
│ │ │ │  <a href="data_types.xhtml#sigil"><code class="inline">~b</code> or <code class="inline">~s</code> sigils </a>the escape sequences for normal
│ │ │ │  strings, above, are used.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Triple-quoted strings and sigils were introduced in Erlang/OTP 27.</p></section><h2 id="type-conversions" class="section-heading">
│ │ │ │    <a href="#type-conversions" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Type Conversions</span>
│ │ │ │  </h2>
│ │ │ │ -<p>There are a number of BIFs for type conversions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="1375248657-1">(</span><span class="ss">hello</span><span class="p" data-group-id="1375248657-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>There are a number of BIFs for type conversions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="6040569476-1">(</span><span class="ss">hello</span><span class="p" data-group-id="6040569476-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="1375248657-2">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1375248657-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +2&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="6040569476-2">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6040569476-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="1375248657-3">(</span><span class="p" data-group-id="1375248657-4">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1375248657-4">&gt;&gt;</span><span class="p" data-group-id="1375248657-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="6040569476-3">(</span><span class="p" data-group-id="6040569476-4">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6040569476-4">&gt;&gt;</span><span class="p" data-group-id="6040569476-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="1375248657-5">(</span><span class="p" data-group-id="1375248657-6">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="1375248657-6">&gt;&gt;</span><span class="p" data-group-id="1375248657-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="6040569476-5">(</span><span class="p" data-group-id="6040569476-6">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="6040569476-6">&gt;&gt;</span><span class="p" data-group-id="6040569476-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nf">list_to_binary</span><span class="p" data-group-id="1375248657-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1375248657-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1375248657-8">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="1375248657-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="1375248657-9">(</span><span class="mf">7.0</span><span class="p" data-group-id="1375248657-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nf">list_to_binary</span><span class="p" data-group-id="6040569476-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6040569476-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6040569476-8">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="6040569476-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +6&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="6040569476-9">(</span><span class="mf">7.0</span><span class="p" data-group-id="6040569476-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;7.00000000000000000000e+00&quot;</span><span class="gp unselectable">
│ │ │ │ -7&gt; </span><span class="nf">list_to_float</span><span class="p" data-group-id="1375248657-10">(</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="1375248657-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +7&gt; </span><span class="nf">list_to_float</span><span class="p" data-group-id="6040569476-10">(</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="6040569476-10">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mf">7.0</span><span class="gp unselectable">
│ │ │ │ -8&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="1375248657-11">(</span><span class="mi">77</span><span class="p" data-group-id="1375248657-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +8&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="6040569476-11">(</span><span class="mi">77</span><span class="p" data-group-id="6040569476-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="s">&quot;77&quot;</span><span class="gp unselectable">
│ │ │ │ -9&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="1375248657-12">(</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="1375248657-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +9&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="6040569476-12">(</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="6040569476-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">77</span><span class="gp unselectable">
│ │ │ │ -10&gt; </span><span class="nf">tuple_to_list</span><span class="p" data-group-id="1375248657-13">(</span><span class="p" data-group-id="1375248657-14">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1375248657-14">}</span><span class="p" data-group-id="1375248657-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1375248657-15">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1375248657-15">]</span><span class="gp unselectable">
│ │ │ │ -11&gt; </span><span class="nf">list_to_tuple</span><span class="p" data-group-id="1375248657-16">(</span><span class="p" data-group-id="1375248657-17">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1375248657-17">]</span><span class="p" data-group-id="1375248657-16">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1375248657-18">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1375248657-18">}</span><span class="gp unselectable">
│ │ │ │ -12&gt; </span><span class="nf">term_to_binary</span><span class="p" data-group-id="1375248657-19">(</span><span class="p" data-group-id="1375248657-20">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1375248657-20">}</span><span class="p" data-group-id="1375248657-19">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1375248657-21">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="1375248657-21">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -13&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="1375248657-22">(</span><span class="p" data-group-id="1375248657-23">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="1375248657-23">&gt;&gt;</span><span class="p" data-group-id="1375248657-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1375248657-24">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1375248657-24">}</span><span class="gp unselectable">
│ │ │ │ -14&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="1375248657-25">(</span><span class="p" data-group-id="1375248657-26">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="1375248657-26">&gt;&gt;</span><span class="p" data-group-id="1375248657-25">)</span><span class="p">.</span><span class="w">
│ │ │ │ +10&gt; </span><span class="nf">tuple_to_list</span><span class="p" data-group-id="6040569476-13">(</span><span class="p" data-group-id="6040569476-14">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6040569476-14">}</span><span class="p" data-group-id="6040569476-13">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6040569476-15">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6040569476-15">]</span><span class="gp unselectable">
│ │ │ │ +11&gt; </span><span class="nf">list_to_tuple</span><span class="p" data-group-id="6040569476-16">(</span><span class="p" data-group-id="6040569476-17">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6040569476-17">]</span><span class="p" data-group-id="6040569476-16">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6040569476-18">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6040569476-18">}</span><span class="gp unselectable">
│ │ │ │ +12&gt; </span><span class="nf">term_to_binary</span><span class="p" data-group-id="6040569476-19">(</span><span class="p" data-group-id="6040569476-20">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6040569476-20">}</span><span class="p" data-group-id="6040569476-19">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6040569476-21">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="6040569476-21">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +13&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="6040569476-22">(</span><span class="p" data-group-id="6040569476-23">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="6040569476-23">&gt;&gt;</span><span class="p" data-group-id="6040569476-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6040569476-24">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6040569476-24">}</span><span class="gp unselectable">
│ │ │ │ +14&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="6040569476-25">(</span><span class="p" data-group-id="6040569476-26">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="6040569476-26">&gt;&gt;</span><span class="p" data-group-id="6040569476-25">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">77</span><span class="gp unselectable">
│ │ │ │ -15&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="1375248657-27">(</span><span class="mi">77</span><span class="p" data-group-id="1375248657-27">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1375248657-28">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="1375248657-28">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -16&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="1375248657-29">(</span><span class="mf">7.0</span><span class="p" data-group-id="1375248657-29">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1375248657-30">&lt;&lt;</span><span class="s">&quot;7.00000000000000000000e+00&quot;</span><span class="p" data-group-id="1375248657-30">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ -17&gt; </span><span class="nf">binary_to_float</span><span class="p" data-group-id="1375248657-31">(</span><span class="p" data-group-id="1375248657-32">&lt;&lt;</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="1375248657-32">&gt;&gt;</span><span class="p" data-group-id="1375248657-31">)</span><span class="p">.</span><span class="w">
│ │ │ │ +15&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="6040569476-27">(</span><span class="mi">77</span><span class="p" data-group-id="6040569476-27">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6040569476-28">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="6040569476-28">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +16&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="6040569476-29">(</span><span class="mf">7.0</span><span class="p" data-group-id="6040569476-29">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6040569476-30">&lt;&lt;</span><span class="s">&quot;7.00000000000000000000e+00&quot;</span><span class="p" data-group-id="6040569476-30">&gt;&gt;</span><span class="gp unselectable">
│ │ │ │ +17&gt; </span><span class="nf">binary_to_float</span><span class="p" data-group-id="6040569476-31">(</span><span class="p" data-group-id="6040569476-32">&lt;&lt;</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="6040569476-32">&gt;&gt;</span><span class="p" data-group-id="6040569476-31">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mf">7.0</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/create_target.xhtml
│ │ │ │ @@ -43,21 +43,21 @@
│ │ │ │    <span class="text">Creating a Target System</span>
│ │ │ │  </h2>
│ │ │ │  <p>It is assumed that you have a working Erlang/OTP system structured according to
│ │ │ │  the OTP design principles.</p><p><em>Step 1.</em> Create a <code class="inline">.rel</code> file (see the <a href="../../../lib/sasl/doc/html/rel.xhtml">rel(4)</a> manual page in
│ │ │ │  SASL), which specifies the ERTS version and lists all applications that are to
│ │ │ │  be included in the new basic target system. An example is the following
│ │ │ │  <code class="inline">mysystem.rel</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% mysystem.rel</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4328144003-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4328144003-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;FIRST&quot;</span><span class="p" data-group-id="4328144003-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4328144003-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.10.4&quot;</span><span class="p" data-group-id="4328144003-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4328144003-4">[</span><span class="p" data-group-id="4328144003-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.16.4&quot;</span><span class="p" data-group-id="4328144003-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4328144003-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.19.4&quot;</span><span class="p" data-group-id="4328144003-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4328144003-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.3.4&quot;</span><span class="p" data-group-id="4328144003-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4328144003-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="4328144003-8">}</span><span class="p" data-group-id="4328144003-4">]</span><span class="p" data-group-id="4328144003-1">}</span><span class="p">.</span></code></pre><p>The listed applications are not only original Erlang/OTP applications but
│ │ │ │ +</span><span class="p" data-group-id="3079582123-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="3079582123-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;FIRST&quot;</span><span class="p" data-group-id="3079582123-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="3079582123-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.10.4&quot;</span><span class="p" data-group-id="3079582123-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="3079582123-4">[</span><span class="p" data-group-id="3079582123-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.16.4&quot;</span><span class="p" data-group-id="3079582123-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="3079582123-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.19.4&quot;</span><span class="p" data-group-id="3079582123-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="3079582123-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.3.4&quot;</span><span class="p" data-group-id="3079582123-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="3079582123-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="3079582123-8">}</span><span class="p" data-group-id="3079582123-4">]</span><span class="p" data-group-id="3079582123-1">}</span><span class="p">.</span></code></pre><p>The listed applications are not only original Erlang/OTP applications but
│ │ │ │  possibly also new applications that you have written (here exemplified by the
│ │ │ │  application Pea (<code class="inline">pea</code>)).</p><p><em>Step 2.</em> Start Erlang/OTP from the directory where the <code class="inline">mysystem.rel</code> file
│ │ │ │  resides:</p><pre><code class="text">% erl -pa /home/user/target_system/myapps/pea-1.0/ebin</code></pre><p>The <code class="inline">-pa</code> argument prepends the path to the <code class="inline">ebin</code> directory for
│ │ │ │  the Pea application to the code path.</p><p><em>Step 3.</em> Create the target system:</p><pre><code class="text">1&gt; target_system:create(&quot;mysystem&quot;).</code></pre><p>The function <code class="inline">target_system:create/1</code> performs the following:</p><ol><li><p>Reads the file <code class="inline">mysystem.rel</code> and creates a new file <code class="inline">plain.rel</code>.
│ │ │ │  The new file is identical to the original, except that it only
│ │ │ │  lists the Kernel and STDLIB applications.</p></li><li><p>From the files <code class="inline">mysystem.rel</code> and <code class="inline">plain.rel</code> creates the files
│ │ │ │  <code class="inline">mysystem.script</code>, <code class="inline">mysystem.boot</code>, <code class="inline">plain.script</code>, and <code class="inline">plain.boot</code>
│ │ │ │ @@ -147,25 +147,25 @@
│ │ │ │    <a href="#creating-the-next-version" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Creating the Next Version</span>
│ │ │ │  </h2>
│ │ │ │  <p>In this example the Pea application has been changed, and so are the
│ │ │ │  applications ERTS, Kernel, STDLIB and SASL.</p><p><em>Step 1.</em> Create the file <code class="inline">.rel</code>:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% mysystem2.rel</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2489223080-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2489223080-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;SECOND&quot;</span><span class="p" data-group-id="2489223080-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2489223080-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;6.0&quot;</span><span class="p" data-group-id="2489223080-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2489223080-4">[</span><span class="p" data-group-id="2489223080-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;3.0&quot;</span><span class="p" data-group-id="2489223080-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2489223080-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="2489223080-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2489223080-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.4&quot;</span><span class="p" data-group-id="2489223080-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="2489223080-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="2489223080-8">}</span><span class="p" data-group-id="2489223080-4">]</span><span class="p" data-group-id="2489223080-1">}</span><span class="p">.</span></code></pre><p><em>Step 2.</em> Create the application upgrade file (see
│ │ │ │ +</span><span class="p" data-group-id="2637974178-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2637974178-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;SECOND&quot;</span><span class="p" data-group-id="2637974178-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2637974178-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;6.0&quot;</span><span class="p" data-group-id="2637974178-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2637974178-4">[</span><span class="p" data-group-id="2637974178-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;3.0&quot;</span><span class="p" data-group-id="2637974178-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="2637974178-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="2637974178-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="2637974178-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.4&quot;</span><span class="p" data-group-id="2637974178-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="2637974178-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="2637974178-8">}</span><span class="p" data-group-id="2637974178-4">]</span><span class="p" data-group-id="2637974178-1">}</span><span class="p">.</span></code></pre><p><em>Step 2.</em> Create the application upgrade file (see
│ │ │ │  <a href="../../../lib/sasl/doc/html/appup.xhtml">appup</a> in SASL) for Pea, for example:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% pea.appup</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8093072195-1">{</span><span class="s">&quot;2.0&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8093072195-2">[</span><span class="p" data-group-id="8093072195-3">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="8093072195-4">[</span><span class="p" data-group-id="8093072195-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="8093072195-5">}</span><span class="p" data-group-id="8093072195-4">]</span><span class="p" data-group-id="8093072195-3">}</span><span class="p" data-group-id="8093072195-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8093072195-6">[</span><span class="p" data-group-id="8093072195-7">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="8093072195-8">[</span><span class="p" data-group-id="8093072195-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="8093072195-9">}</span><span class="p" data-group-id="8093072195-8">]</span><span class="p" data-group-id="8093072195-7">}</span><span class="p" data-group-id="8093072195-6">]</span><span class="p" data-group-id="8093072195-1">}</span><span class="p">.</span></code></pre><p><em>Step 3.</em> From the directory where the file <code class="inline">mysystem2.rel</code> resides, start the
│ │ │ │ +</span><span class="p" data-group-id="9603993098-1">{</span><span class="s">&quot;2.0&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9603993098-2">[</span><span class="p" data-group-id="9603993098-3">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="9603993098-4">[</span><span class="p" data-group-id="9603993098-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="9603993098-5">}</span><span class="p" data-group-id="9603993098-4">]</span><span class="p" data-group-id="9603993098-3">}</span><span class="p" data-group-id="9603993098-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9603993098-6">[</span><span class="p" data-group-id="9603993098-7">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="9603993098-8">[</span><span class="p" data-group-id="9603993098-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="9603993098-9">}</span><span class="p" data-group-id="9603993098-8">]</span><span class="p" data-group-id="9603993098-7">}</span><span class="p" data-group-id="9603993098-6">]</span><span class="p" data-group-id="9603993098-1">}</span><span class="p">.</span></code></pre><p><em>Step 3.</em> From the directory where the file <code class="inline">mysystem2.rel</code> resides, start the
│ │ │ │  Erlang/OTP system, giving the path to the new version of Pea:</p><pre><code class="text">% erl -pa /home/user/target_system/myapps/pea-2.0/ebin</code></pre><p><em>Step 4.</em> Create the release upgrade file (see <a href="../../../lib/sasl/doc/html/relup.xhtml">relup</a>
│ │ │ │  in SASL):</p><pre><code class="text">1&gt; systools:make_relup(&quot;mysystem2&quot;,[&quot;mysystem&quot;],[&quot;mysystem&quot;],
│ │ │ │      [{path,[&quot;/home/user/target_system/myapps/pea-1.0/ebin&quot;,
│ │ │ │      &quot;/my/old/erlang/lib/*/ebin&quot;]}]).</code></pre><p>Here <code class="inline">&quot;mysystem&quot;</code> is the base release and <code class="inline">&quot;mysystem2&quot;</code> is the release to
│ │ │ │  upgrade to.</p><p>The <code class="inline">path</code> option is used for pointing out the old version of all applications.
│ │ │ │  (The new versions are already in the code path - assuming of course that the
│ │ │ │  Erlang node on which this is executed is running the correct version of
│ │ │ │ @@ -197,21 +197,21 @@
│ │ │ │  {continue_after_restart,&quot;FIRST&quot;,[]}
│ │ │ │  heart: Tue Apr  1 12:15:10 2014: Erlang has closed.
│ │ │ │  heart: Tue Apr  1 12:15:11 2014: Executed &quot;/usr/local/erl-target/bin/start /usr/local/erl-target/releases/new_start_erl.data&quot; -&gt; 0. Terminating.
│ │ │ │  [End]</code></pre><p>The above return value and output after the call to
│ │ │ │  <a href="../../../lib/sasl/doc/html/release_handler.html#install_release/1"><code class="inline">release_handler:install_release/1</code></a> means that the <code class="inline">release_handler</code> has
│ │ │ │  restarted the node by using <code class="inline">heart</code>. This is always done when the upgrade
│ │ │ │  involves a change of the applications ERTS, Kernel, STDLIB, or SASL. For more
│ │ │ │ -information, see <a href="upgrade.xhtml">Upgrade when Erlang/OTP has Changed</a>.</p><p>The node is accessible through a new pipe:</p><pre><code class="text">% /usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</code></pre><p>List the available releases in the system:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">which_releases</span><span class="p" data-group-id="1105466598-1">(</span><span class="p" data-group-id="1105466598-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1105466598-2">[</span><span class="p" data-group-id="1105466598-3">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;SECOND&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1105466598-4">[</span><span class="s">&quot;kernel-3.0&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-2.0&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-2.0&quot;</span><span class="p" data-group-id="1105466598-4">]</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">current</span><span class="p" data-group-id="1105466598-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1105466598-5">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;FIRST&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1105466598-6">[</span><span class="s">&quot;kernel-2.16.4&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-1.19.4&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.3.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-1.0&quot;</span><span class="p" data-group-id="1105466598-6">]</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="ss">permanent</span><span class="p" data-group-id="1105466598-5">}</span><span class="p" data-group-id="1105466598-2">]</span></code></pre><p>Our new release, &quot;SECOND&quot;, is now the current release, but we can also see that
│ │ │ │ +information, see <a href="upgrade.xhtml">Upgrade when Erlang/OTP has Changed</a>.</p><p>The node is accessible through a new pipe:</p><pre><code class="text">% /usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</code></pre><p>List the available releases in the system:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">which_releases</span><span class="p" data-group-id="9083195448-1">(</span><span class="p" data-group-id="9083195448-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9083195448-2">[</span><span class="p" data-group-id="9083195448-3">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;SECOND&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9083195448-4">[</span><span class="s">&quot;kernel-3.0&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-2.0&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-2.0&quot;</span><span class="p" data-group-id="9083195448-4">]</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="ss">current</span><span class="p" data-group-id="9083195448-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9083195448-5">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;FIRST&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="9083195448-6">[</span><span class="s">&quot;kernel-2.16.4&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-1.19.4&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.3.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-1.0&quot;</span><span class="p" data-group-id="9083195448-6">]</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="ss">permanent</span><span class="p" data-group-id="9083195448-5">}</span><span class="p" data-group-id="9083195448-2">]</span></code></pre><p>Our new release, &quot;SECOND&quot;, is now the current release, but we can also see that
│ │ │ │  our &quot;FIRST&quot; release is still permanent. This means that if the node would be
│ │ │ │  restarted now, it would come up running the &quot;FIRST&quot; release again.</p><p><em>Step 3.</em> Make the new release permanent:</p><pre><code class="text">2&gt; release_handler:make_permanent(&quot;SECOND&quot;).</code></pre><p>Check the releases again:</p><pre><code class="c">3&gt; release_handler:which_releases().
│ │ │ │  [{&quot;MYSYSTEM&quot;,&quot;SECOND&quot;,
│ │ │ │    [&quot;kernel-3.0&quot;,&quot;stdlib-2.0&quot;,&quot;sasl-2.4&quot;,&quot;pea-2.0&quot;],
│ │ │ │    permanent},
│ │ │ │   {&quot;MYSYSTEM&quot;,&quot;FIRST&quot;,
│ │ │ │    [&quot;kernel-2.16.4&quot;,&quot;stdlib-1.19.4&quot;,&quot;sasl-2.3.4&quot;,&quot;pea-1.0&quot;],
│ │ │ │ @@ -220,264 +220,264 @@
│ │ │ │    <a href="#listing-of-target_system-erl" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Listing of target_system.erl</span>
│ │ │ │  </h2>
│ │ │ │  <p>This module can also be found in the <code class="inline">examples</code> directory of the SASL
│ │ │ │  application.</p><pre><code class="makeup erlang" translate="no"><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6359730344-1">(</span><span class="ss">target_system</span><span class="p" data-group-id="6359730344-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6359730344-2">(</span><span class="p" data-group-id="6359730344-3">[</span><span class="ss">create</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">create</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">install</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6359730344-3">]</span><span class="p" data-group-id="6359730344-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9437603207-1">(</span><span class="ss">target_system</span><span class="p" data-group-id="9437603207-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9437603207-2">(</span><span class="p" data-group-id="9437603207-3">[</span><span class="ss">create</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">create</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">install</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9437603207-3">]</span><span class="p" data-group-id="9437603207-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% Note: RelFileName below is the *stem* without trailing .rel,</span><span class="w">
│ │ │ │  </span><span class="c1">%% .script etc.</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% create(RelFileName)</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │ -</span><span class="nf">create</span><span class="p" data-group-id="6359730344-4">(</span><span class="n">RelFileName</span><span class="p" data-group-id="6359730344-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">create</span><span class="p" data-group-id="6359730344-5">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="p" data-group-id="6359730344-6">[</span><span class="p" data-group-id="6359730344-6">]</span><span class="p" data-group-id="6359730344-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">create</span><span class="p" data-group-id="9437603207-4">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9437603207-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">create</span><span class="p" data-group-id="9437603207-5">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="p" data-group-id="9437603207-6">[</span><span class="p" data-group-id="9437603207-6">]</span><span class="p" data-group-id="9437603207-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">create</span><span class="p" data-group-id="6359730344-7">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="6359730344-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">create</span><span class="p" data-group-id="9437603207-7">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9437603207-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">RelFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Dir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="6359730344-8">(</span><span class="n">RelFileName</span><span class="p" data-group-id="6359730344-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">PlainRelFileName</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-9">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;plain&quot;</span><span class="p" data-group-id="6359730344-9">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Dir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="9437603207-8">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9437603207-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">PlainRelFileName</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-9">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;plain&quot;</span><span class="p" data-group-id="9437603207-9">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="n">PlainRelFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">PlainRelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-10">(</span><span class="s">&quot;Reading file: ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-11">[</span><span class="n">RelFile</span><span class="p" data-group-id="6359730344-11">]</span><span class="p" data-group-id="6359730344-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-13">[</span><span class="n">RelSpec</span><span class="p" data-group-id="6359730344-13">]</span><span class="p" data-group-id="6359730344-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">consult</span><span class="p" data-group-id="6359730344-14">(</span><span class="n">RelFile</span><span class="p" data-group-id="6359730344-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-15">(</span><span class="s">&quot;Creating file: ~ts from ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="6359730344-16">[</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="n">RelFile</span><span class="p" data-group-id="6359730344-16">]</span><span class="p" data-group-id="6359730344-15">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-17">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="6359730344-18">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="6359730344-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="p" data-group-id="6359730344-19">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="6359730344-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ -     </span><span class="n">AppVsns</span><span class="p" data-group-id="6359730344-17">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelSpec</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">PlainRelSpec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6359730344-20">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="p" data-group-id="6359730344-21">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="6359730344-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="p" data-group-id="6359730344-22">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="6359730344-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ -                    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="6359730344-23">(</span><span class="nf">fun</span><span class="p" data-group-id="6359730344-24">(</span><span class="p" data-group-id="6359730344-25">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6359730344-25">}</span><span class="p" data-group-id="6359730344-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-10">(</span><span class="s">&quot;Reading file: ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-11">[</span><span class="n">RelFile</span><span class="p" data-group-id="9437603207-11">]</span><span class="p" data-group-id="9437603207-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-13">[</span><span class="n">RelSpec</span><span class="p" data-group-id="9437603207-13">]</span><span class="p" data-group-id="9437603207-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">consult</span><span class="p" data-group-id="9437603207-14">(</span><span class="n">RelFile</span><span class="p" data-group-id="9437603207-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-15">(</span><span class="s">&quot;Creating file: ~ts from ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9437603207-16">[</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="n">RelFile</span><span class="p" data-group-id="9437603207-16">]</span><span class="p" data-group-id="9437603207-15">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-17">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="9437603207-18">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="9437603207-18">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="p" data-group-id="9437603207-19">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="9437603207-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ +     </span><span class="n">AppVsns</span><span class="p" data-group-id="9437603207-17">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelSpec</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">PlainRelSpec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9437603207-20">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="p" data-group-id="9437603207-21">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="9437603207-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="p" data-group-id="9437603207-22">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="9437603207-22">}</span><span class="p">,</span><span class="w">
│ │ │ │ +                    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="9437603207-23">(</span><span class="nf">fun</span><span class="p" data-group-id="9437603207-24">(</span><span class="p" data-group-id="9437603207-25">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9437603207-25">}</span><span class="p" data-group-id="9437603207-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                                           </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ │ -                                    </span><span class="p" data-group-id="6359730344-26">(</span><span class="p" data-group-id="6359730344-27">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6359730344-27">}</span><span class="p" data-group-id="6359730344-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                                    </span><span class="p" data-group-id="9437603207-26">(</span><span class="p" data-group-id="9437603207-27">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9437603207-27">}</span><span class="p" data-group-id="9437603207-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                                           </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ │ -                                    </span><span class="p" data-group-id="6359730344-28">(</span><span class="p">_</span><span class="p" data-group-id="6359730344-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                                    </span><span class="p" data-group-id="9437603207-28">(</span><span class="p">_</span><span class="p" data-group-id="9437603207-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │                                           </span><span class="ss">false</span><span class="w">
│ │ │ │ -                                 </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsns</span><span class="p" data-group-id="6359730344-23">)</span><span class="w">
│ │ │ │ -                   </span><span class="p" data-group-id="6359730344-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="6359730344-29">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="6359730344-30">(</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-31">[</span><span class="ss">write</span><span class="p" data-group-id="6359730344-31">]</span><span class="p" data-group-id="6359730344-30">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-32">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-33">[</span><span class="n">PlainRelSpec</span><span class="p" data-group-id="6359730344-33">]</span><span class="p" data-group-id="6359730344-32">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="6359730344-34">(</span><span class="n">Fd</span><span class="p" data-group-id="6359730344-34">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-35">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -	      </span><span class="p" data-group-id="6359730344-36">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">PlainRelFileName</span><span class="p" data-group-id="6359730344-36">]</span><span class="p" data-group-id="6359730344-35">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">make_script</span><span class="p" data-group-id="6359730344-37">(</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="6359730344-37">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-38">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="6359730344-39">[</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="6359730344-39">]</span><span class="p" data-group-id="6359730344-38">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">make_script</span><span class="p" data-group-id="6359730344-40">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="6359730344-40">)</span><span class="p">,</span><span class="w">
│ │ │ │ +                                 </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsns</span><span class="p" data-group-id="9437603207-23">)</span><span class="w">
│ │ │ │ +                   </span><span class="p" data-group-id="9437603207-20">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="9437603207-29">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="9437603207-30">(</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-31">[</span><span class="ss">write</span><span class="p" data-group-id="9437603207-31">]</span><span class="p" data-group-id="9437603207-30">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-32">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-33">[</span><span class="n">PlainRelSpec</span><span class="p" data-group-id="9437603207-33">]</span><span class="p" data-group-id="9437603207-32">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9437603207-34">(</span><span class="n">Fd</span><span class="p" data-group-id="9437603207-34">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-35">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +	      </span><span class="p" data-group-id="9437603207-36">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">PlainRelFileName</span><span class="p" data-group-id="9437603207-36">]</span><span class="p" data-group-id="9437603207-35">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">make_script</span><span class="p" data-group-id="9437603207-37">(</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9437603207-37">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-38">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9437603207-39">[</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="9437603207-39">]</span><span class="p" data-group-id="9437603207-38">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">make_script</span><span class="p" data-group-id="9437603207-40">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9437603207-40">)</span><span class="p">,</span><span class="w">
│ │ │ │  
│ │ │ │      </span><span class="n">TarFileName</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.tar.gz&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-41">(</span><span class="s">&quot;Creating tar file ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-42">[</span><span class="n">TarFileName</span><span class="p" data-group-id="6359730344-42">]</span><span class="p" data-group-id="6359730344-41">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">make_tar</span><span class="p" data-group-id="6359730344-43">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="6359730344-43">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-41">(</span><span class="s">&quot;Creating tar file ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-42">[</span><span class="n">TarFileName</span><span class="p" data-group-id="9437603207-42">]</span><span class="p" data-group-id="9437603207-41">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">make_tar</span><span class="p" data-group-id="9437603207-43">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9437603207-43">)</span><span class="p">,</span><span class="w">
│ │ │ │  
│ │ │ │ -    </span><span class="n">TmpDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-44">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;tmp&quot;</span><span class="p" data-group-id="6359730344-44">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-45">(</span><span class="s">&quot;Creating directory ~tp ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="6359730344-46">[</span><span class="n">TmpDir</span><span class="p" data-group-id="6359730344-46">]</span><span class="p" data-group-id="6359730344-45">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="6359730344-47">(</span><span class="n">TmpDir</span><span class="p" data-group-id="6359730344-47">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-48">(</span><span class="s">&quot;Extracting ~ts into directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-49">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="6359730344-49">]</span><span class="p" data-group-id="6359730344-48">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">extract_tar</span><span class="p" data-group-id="6359730344-50">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="n">TmpDir</span><span class="p" data-group-id="6359730344-50">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="n">TmpBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-51">(</span><span class="p" data-group-id="6359730344-52">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="6359730344-52">]</span><span class="p" data-group-id="6359730344-51">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-53">(</span><span class="p" data-group-id="6359730344-54">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="6359730344-54">]</span><span class="p" data-group-id="6359730344-53">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-55">(</span><span class="s">&quot;Deleting \&quot;erl\&quot; and \&quot;start\&quot; in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="6359730344-56">[</span><span class="n">ErtsBinDir</span><span class="p" data-group-id="6359730344-56">]</span><span class="p" data-group-id="6359730344-55">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="6359730344-57">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-58">(</span><span class="p" data-group-id="6359730344-59">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erl&quot;</span><span class="p" data-group-id="6359730344-59">]</span><span class="p" data-group-id="6359730344-58">)</span><span class="p" data-group-id="6359730344-57">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="6359730344-60">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-61">(</span><span class="p" data-group-id="6359730344-62">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="6359730344-62">]</span><span class="p" data-group-id="6359730344-61">)</span><span class="p" data-group-id="6359730344-60">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-63">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-64">[</span><span class="n">TmpBinDir</span><span class="p" data-group-id="6359730344-64">]</span><span class="p" data-group-id="6359730344-63">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="6359730344-65">(</span><span class="n">TmpBinDir</span><span class="p" data-group-id="6359730344-65">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-66">(</span><span class="s">&quot;Copying file \&quot;~ts.boot\&quot; to ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="6359730344-67">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-68">(</span><span class="p" data-group-id="6359730344-69">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="6359730344-69">]</span><span class="p" data-group-id="6359730344-68">)</span><span class="p" data-group-id="6359730344-67">]</span><span class="p" data-group-id="6359730344-66">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="6359730344-70">(</span><span class="n">PlainRelFileName</span><span class="o">++</span><span class="s">&quot;.boot&quot;</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-71">(</span><span class="p" data-group-id="6359730344-72">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="6359730344-72">]</span><span class="p" data-group-id="6359730344-71">)</span><span class="p" data-group-id="6359730344-70">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">TmpDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-44">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;tmp&quot;</span><span class="p" data-group-id="9437603207-44">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-45">(</span><span class="s">&quot;Creating directory ~tp ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9437603207-46">[</span><span class="n">TmpDir</span><span class="p" data-group-id="9437603207-46">]</span><span class="p" data-group-id="9437603207-45">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="9437603207-47">(</span><span class="n">TmpDir</span><span class="p" data-group-id="9437603207-47">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-48">(</span><span class="s">&quot;Extracting ~ts into directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-49">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="9437603207-49">]</span><span class="p" data-group-id="9437603207-48">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">extract_tar</span><span class="p" data-group-id="9437603207-50">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="n">TmpDir</span><span class="p" data-group-id="9437603207-50">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="n">TmpBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-51">(</span><span class="p" data-group-id="9437603207-52">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9437603207-52">]</span><span class="p" data-group-id="9437603207-51">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-53">(</span><span class="p" data-group-id="9437603207-54">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9437603207-54">]</span><span class="p" data-group-id="9437603207-53">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-55">(</span><span class="s">&quot;Deleting \&quot;erl\&quot; and \&quot;start\&quot; in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9437603207-56">[</span><span class="n">ErtsBinDir</span><span class="p" data-group-id="9437603207-56">]</span><span class="p" data-group-id="9437603207-55">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="9437603207-57">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-58">(</span><span class="p" data-group-id="9437603207-59">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erl&quot;</span><span class="p" data-group-id="9437603207-59">]</span><span class="p" data-group-id="9437603207-58">)</span><span class="p" data-group-id="9437603207-57">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="9437603207-60">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-61">(</span><span class="p" data-group-id="9437603207-62">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="9437603207-62">]</span><span class="p" data-group-id="9437603207-61">)</span><span class="p" data-group-id="9437603207-60">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-63">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-64">[</span><span class="n">TmpBinDir</span><span class="p" data-group-id="9437603207-64">]</span><span class="p" data-group-id="9437603207-63">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="9437603207-65">(</span><span class="n">TmpBinDir</span><span class="p" data-group-id="9437603207-65">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-66">(</span><span class="s">&quot;Copying file \&quot;~ts.boot\&quot; to ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9437603207-67">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-68">(</span><span class="p" data-group-id="9437603207-69">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="9437603207-69">]</span><span class="p" data-group-id="9437603207-68">)</span><span class="p" data-group-id="9437603207-67">]</span><span class="p" data-group-id="9437603207-66">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9437603207-70">(</span><span class="n">PlainRelFileName</span><span class="o">++</span><span class="s">&quot;.boot&quot;</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-71">(</span><span class="p" data-group-id="9437603207-72">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="9437603207-72">]</span><span class="p" data-group-id="9437603207-71">)</span><span class="p" data-group-id="9437603207-70">)</span><span class="p">,</span><span class="w">
│ │ │ │  
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-73">(</span><span class="s">&quot;Copying files \&quot;epmd\&quot;, \&quot;run_erl\&quot; and \&quot;to_erl\&quot; from \n&quot;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-73">(</span><span class="s">&quot;Copying files \&quot;epmd\&quot;, \&quot;run_erl\&quot; and \&quot;to_erl\&quot; from \n&quot;</span><span class="w">
│ │ │ │                </span><span class="s">&quot;~ts to ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="p" data-group-id="6359730344-74">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">TmpBinDir</span><span class="p" data-group-id="6359730344-74">]</span><span class="p" data-group-id="6359730344-73">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="6359730344-75">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-76">(</span><span class="p" data-group-id="6359730344-77">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="6359730344-77">]</span><span class="p" data-group-id="6359730344-76">)</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-78">(</span><span class="p" data-group-id="6359730344-79">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="6359730344-79">]</span><span class="p" data-group-id="6359730344-78">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-80">[</span><span class="ss">preserve</span><span class="p" data-group-id="6359730344-80">]</span><span class="p" data-group-id="6359730344-75">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="6359730344-81">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-82">(</span><span class="p" data-group-id="6359730344-83">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="6359730344-83">]</span><span class="p" data-group-id="6359730344-82">)</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-84">(</span><span class="p" data-group-id="6359730344-85">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="6359730344-85">]</span><span class="p" data-group-id="6359730344-84">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-86">[</span><span class="ss">preserve</span><span class="p" data-group-id="6359730344-86">]</span><span class="p" data-group-id="6359730344-81">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="6359730344-87">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-88">(</span><span class="p" data-group-id="6359730344-89">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="6359730344-89">]</span><span class="p" data-group-id="6359730344-88">)</span><span class="p">,</span><span class="w">
│ │ │ │ -              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-90">(</span><span class="p" data-group-id="6359730344-91">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="6359730344-91">]</span><span class="p" data-group-id="6359730344-90">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-92">[</span><span class="ss">preserve</span><span class="p" data-group-id="6359730344-92">]</span><span class="p" data-group-id="6359730344-87">)</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="p" data-group-id="9437603207-74">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">TmpBinDir</span><span class="p" data-group-id="9437603207-74">]</span><span class="p" data-group-id="9437603207-73">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9437603207-75">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-76">(</span><span class="p" data-group-id="9437603207-77">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="9437603207-77">]</span><span class="p" data-group-id="9437603207-76">)</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-78">(</span><span class="p" data-group-id="9437603207-79">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="9437603207-79">]</span><span class="p" data-group-id="9437603207-78">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-80">[</span><span class="ss">preserve</span><span class="p" data-group-id="9437603207-80">]</span><span class="p" data-group-id="9437603207-75">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9437603207-81">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-82">(</span><span class="p" data-group-id="9437603207-83">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="9437603207-83">]</span><span class="p" data-group-id="9437603207-82">)</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-84">(</span><span class="p" data-group-id="9437603207-85">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="9437603207-85">]</span><span class="p" data-group-id="9437603207-84">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-86">[</span><span class="ss">preserve</span><span class="p" data-group-id="9437603207-86">]</span><span class="p" data-group-id="9437603207-81">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9437603207-87">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-88">(</span><span class="p" data-group-id="9437603207-89">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="9437603207-89">]</span><span class="p" data-group-id="9437603207-88">)</span><span class="p">,</span><span class="w">
│ │ │ │ +              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-90">(</span><span class="p" data-group-id="9437603207-91">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="9437603207-91">]</span><span class="p" data-group-id="9437603207-90">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-92">[</span><span class="ss">preserve</span><span class="p" data-group-id="9437603207-92">]</span><span class="p" data-group-id="9437603207-87">)</span><span class="p">,</span><span class="w">
│ │ │ │  
│ │ │ │      </span><span class="c1">%% This is needed if &#39;start&#39; script created from &#39;start.src&#39; shall</span><span class="w">
│ │ │ │      </span><span class="c1">%% be used as it points out this directory as log dir for &#39;run_erl&#39;</span><span class="w">
│ │ │ │ -    </span><span class="n">TmpLogDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-93">(</span><span class="p" data-group-id="6359730344-94">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="6359730344-94">]</span><span class="p" data-group-id="6359730344-93">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-95">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-96">[</span><span class="n">TmpLogDir</span><span class="p" data-group-id="6359730344-96">]</span><span class="p" data-group-id="6359730344-95">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="6359730344-97">(</span><span class="n">TmpLogDir</span><span class="p" data-group-id="6359730344-97">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-98">(</span><span class="p" data-group-id="6359730344-99">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="6359730344-99">]</span><span class="p" data-group-id="6359730344-98">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-100">(</span><span class="s">&quot;Creating ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-101">[</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="6359730344-101">]</span><span class="p" data-group-id="6359730344-100">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">StartErlData</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">io_lib</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-102">(</span><span class="s">&quot;</span><span class="si">~s</span><span class="s"> </span><span class="si">~s</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-103">[</span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="6359730344-103">]</span><span class="p" data-group-id="6359730344-102">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">write_file</span><span class="p" data-group-id="6359730344-104">(</span><span class="n">StartErlDataFile</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="6359730344-104">)</span><span class="p">,</span><span class="w">
│ │ │ │ -
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-105">(</span><span class="s">&quot;Recreating tar file ~ts from contents in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -	      </span><span class="p" data-group-id="6359730344-106">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="6359730344-106">]</span><span class="p" data-group-id="6359730344-105">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-107">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tar</span><span class="p" data-group-id="6359730344-107">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="6359730344-108">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-109">[</span><span class="ss">write</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="6359730344-109">]</span><span class="p" data-group-id="6359730344-108">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">TmpLogDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-93">(</span><span class="p" data-group-id="9437603207-94">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="9437603207-94">]</span><span class="p" data-group-id="9437603207-93">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-95">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-96">[</span><span class="n">TmpLogDir</span><span class="p" data-group-id="9437603207-96">]</span><span class="p" data-group-id="9437603207-95">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="9437603207-97">(</span><span class="n">TmpLogDir</span><span class="p" data-group-id="9437603207-97">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-98">(</span><span class="p" data-group-id="9437603207-99">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="9437603207-99">]</span><span class="p" data-group-id="9437603207-98">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-100">(</span><span class="s">&quot;Creating ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-101">[</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="9437603207-101">]</span><span class="p" data-group-id="9437603207-100">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">StartErlData</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">io_lib</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-102">(</span><span class="s">&quot;</span><span class="si">~s</span><span class="s"> </span><span class="si">~s</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-103">[</span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="9437603207-103">]</span><span class="p" data-group-id="9437603207-102">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">write_file</span><span class="p" data-group-id="9437603207-104">(</span><span class="n">StartErlDataFile</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="9437603207-104">)</span><span class="p">,</span><span class="w">
│ │ │ │ +
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-105">(</span><span class="s">&quot;Recreating tar file ~ts from contents in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +	      </span><span class="p" data-group-id="9437603207-106">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="9437603207-106">]</span><span class="p" data-group-id="9437603207-105">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-107">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tar</span><span class="p" data-group-id="9437603207-107">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="9437603207-108">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-109">[</span><span class="ss">write</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="9437603207-109">]</span><span class="p" data-group-id="9437603207-108">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="c1">%% {ok, Cwd} = file:get_cwd(),</span><span class="w">
│ │ │ │      </span><span class="c1">%% file:set_cwd(&quot;tmp&quot;),</span><span class="w">
│ │ │ │      </span><span class="n">ErtsDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="o">++</span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="6359730344-110">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-111">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="6359730344-111">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-112">[</span><span class="p" data-group-id="6359730344-112">]</span><span class="p" data-group-id="6359730344-110">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="6359730344-113">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-114">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="n">ErtsDir</span><span class="p" data-group-id="6359730344-114">)</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsDir</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-115">[</span><span class="p" data-group-id="6359730344-115">]</span><span class="p" data-group-id="6359730344-113">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="6359730344-116">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-117">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;releases&quot;</span><span class="p" data-group-id="6359730344-117">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-118">[</span><span class="p" data-group-id="6359730344-118">]</span><span class="p" data-group-id="6359730344-116">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="6359730344-119">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-120">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;lib&quot;</span><span class="p" data-group-id="6359730344-120">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;lib&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-121">[</span><span class="p" data-group-id="6359730344-121">]</span><span class="p" data-group-id="6359730344-119">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="6359730344-122">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-123">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="6359730344-123">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-124">[</span><span class="p" data-group-id="6359730344-124">]</span><span class="p" data-group-id="6359730344-122">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="6359730344-125">(</span><span class="n">Tar</span><span class="p" data-group-id="6359730344-125">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9437603207-110">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-111">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9437603207-111">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-112">[</span><span class="p" data-group-id="9437603207-112">]</span><span class="p" data-group-id="9437603207-110">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9437603207-113">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-114">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="n">ErtsDir</span><span class="p" data-group-id="9437603207-114">)</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsDir</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-115">[</span><span class="p" data-group-id="9437603207-115">]</span><span class="p" data-group-id="9437603207-113">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9437603207-116">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-117">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;releases&quot;</span><span class="p" data-group-id="9437603207-117">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-118">[</span><span class="p" data-group-id="9437603207-118">]</span><span class="p" data-group-id="9437603207-116">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9437603207-119">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-120">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;lib&quot;</span><span class="p" data-group-id="9437603207-120">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;lib&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-121">[</span><span class="p" data-group-id="9437603207-121">]</span><span class="p" data-group-id="9437603207-119">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9437603207-122">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-123">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="9437603207-123">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-124">[</span><span class="p" data-group-id="9437603207-124">]</span><span class="p" data-group-id="9437603207-122">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9437603207-125">(</span><span class="n">Tar</span><span class="p" data-group-id="9437603207-125">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="c1">%% file:set_cwd(Cwd),</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-126">(</span><span class="s">&quot;Removing directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="6359730344-127">[</span><span class="n">TmpDir</span><span class="p" data-group-id="6359730344-127">]</span><span class="p" data-group-id="6359730344-126">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="6359730344-128">(</span><span class="n">TmpDir</span><span class="p" data-group-id="6359730344-128">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-126">(</span><span class="s">&quot;Removing directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9437603207-127">[</span><span class="n">TmpDir</span><span class="p" data-group-id="9437603207-127">]</span><span class="p" data-group-id="9437603207-126">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="9437603207-128">(</span><span class="n">TmpDir</span><span class="p" data-group-id="9437603207-128">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  
│ │ │ │ -</span><span class="nf">install</span><span class="p" data-group-id="6359730344-129">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="6359730344-129">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">install</span><span class="p" data-group-id="9437603207-129">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9437603207-129">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">TarFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.tar.gz&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-130">(</span><span class="s">&quot;Extracting ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-131">[</span><span class="n">TarFile</span><span class="p" data-group-id="6359730344-131">]</span><span class="p" data-group-id="6359730344-130">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">extract_tar</span><span class="p" data-group-id="6359730344-132">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="6359730344-132">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-133">(</span><span class="p" data-group-id="6359730344-134">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="6359730344-134">]</span><span class="p" data-group-id="6359730344-133">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-135">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="6359730344-135">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="6359730344-136">(</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="6359730344-136">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-137">[</span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">RelVsn</span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6359730344-137">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">string</span><span class="p">:</span><span class="nf">tokens</span><span class="p" data-group-id="6359730344-138">(</span><span class="n">StartErlData</span><span class="p">,</span><span class="w"> </span><span class="s">&quot; \n&quot;</span><span class="p" data-group-id="6359730344-138">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-139">(</span><span class="p" data-group-id="6359730344-140">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="6359730344-140">]</span><span class="p" data-group-id="6359730344-139">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">BinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-141">(</span><span class="p" data-group-id="6359730344-142">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="6359730344-142">]</span><span class="p" data-group-id="6359730344-141">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-143">(</span><span class="s">&quot;Substituting in erl.src, start.src and start_erl.src to &quot;</span><span class="w">
│ │ │ │ -              </span><span class="s">&quot;form erl, start and start_erl ...\n&quot;</span><span class="p" data-group-id="6359730344-143">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="6359730344-144">(</span><span class="p" data-group-id="6359730344-145">[</span><span class="s">&quot;erl&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="6359730344-145">]</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">BinDir</span><span class="p">,</span><span class="w">
│ │ │ │ -                      </span><span class="p" data-group-id="6359730344-146">[</span><span class="p" data-group-id="6359730344-147">{</span><span class="s">&quot;FINAL_ROOTDIR&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="6359730344-147">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-148">{</span><span class="s">&quot;EMU&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;beam&quot;</span><span class="p" data-group-id="6359730344-148">}</span><span class="p" data-group-id="6359730344-146">]</span><span class="p">,</span><span class="w">
│ │ │ │ -                      </span><span class="p" data-group-id="6359730344-149">[</span><span class="ss">preserve</span><span class="p" data-group-id="6359730344-149">]</span><span class="p" data-group-id="6359730344-144">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-130">(</span><span class="s">&quot;Extracting ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-131">[</span><span class="n">TarFile</span><span class="p" data-group-id="9437603207-131">]</span><span class="p" data-group-id="9437603207-130">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">extract_tar</span><span class="p" data-group-id="9437603207-132">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9437603207-132">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-133">(</span><span class="p" data-group-id="9437603207-134">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="9437603207-134">]</span><span class="p" data-group-id="9437603207-133">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-135">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="9437603207-135">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="9437603207-136">(</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="9437603207-136">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-137">[</span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">RelVsn</span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9437603207-137">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">string</span><span class="p">:</span><span class="nf">tokens</span><span class="p" data-group-id="9437603207-138">(</span><span class="n">StartErlData</span><span class="p">,</span><span class="w"> </span><span class="s">&quot; \n&quot;</span><span class="p" data-group-id="9437603207-138">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-139">(</span><span class="p" data-group-id="9437603207-140">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9437603207-140">]</span><span class="p" data-group-id="9437603207-139">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">BinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-141">(</span><span class="p" data-group-id="9437603207-142">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9437603207-142">]</span><span class="p" data-group-id="9437603207-141">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-143">(</span><span class="s">&quot;Substituting in erl.src, start.src and start_erl.src to &quot;</span><span class="w">
│ │ │ │ +              </span><span class="s">&quot;form erl, start and start_erl ...\n&quot;</span><span class="p" data-group-id="9437603207-143">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="9437603207-144">(</span><span class="p" data-group-id="9437603207-145">[</span><span class="s">&quot;erl&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="9437603207-145">]</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">BinDir</span><span class="p">,</span><span class="w">
│ │ │ │ +                      </span><span class="p" data-group-id="9437603207-146">[</span><span class="p" data-group-id="9437603207-147">{</span><span class="s">&quot;FINAL_ROOTDIR&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9437603207-147">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-148">{</span><span class="s">&quot;EMU&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;beam&quot;</span><span class="p" data-group-id="9437603207-148">}</span><span class="p" data-group-id="9437603207-146">]</span><span class="p">,</span><span class="w">
│ │ │ │ +                      </span><span class="p" data-group-id="9437603207-149">[</span><span class="ss">preserve</span><span class="p" data-group-id="9437603207-149">]</span><span class="p" data-group-id="9437603207-144">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="c1">%%! Workaround for pre OTP 17.0: start.src and start_erl.src did</span><span class="w">
│ │ │ │      </span><span class="c1">%%! not have correct permissions, so the above &#39;preserve&#39; option did not help</span><span class="w">
│ │ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="6359730344-150">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-151">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="6359730344-151">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="6359730344-150">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="6359730344-152">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-153">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="6359730344-153">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="6359730344-152">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="9437603207-150">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-151">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="9437603207-151">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="9437603207-150">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="9437603207-152">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-153">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="9437603207-153">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="9437603207-152">)</span><span class="p">,</span><span class="w">
│ │ │ │  
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="6359730344-154">(</span><span class="s">&quot;Creating the RELEASES file ...\n&quot;</span><span class="p" data-group-id="6359730344-154">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">create_RELEASES</span><span class="p" data-group-id="6359730344-155">(</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-156">(</span><span class="p" data-group-id="6359730344-157">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -					    </span><span class="nc">filename</span><span class="p">:</span><span class="nf">basename</span><span class="p" data-group-id="6359730344-158">(</span><span class="n">RelFileName</span><span class="p" data-group-id="6359730344-158">)</span><span class="p" data-group-id="6359730344-157">]</span><span class="p" data-group-id="6359730344-156">)</span><span class="p" data-group-id="6359730344-155">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9437603207-154">(</span><span class="s">&quot;Creating the RELEASES file ...\n&quot;</span><span class="p" data-group-id="9437603207-154">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">create_RELEASES</span><span class="p" data-group-id="9437603207-155">(</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-156">(</span><span class="p" data-group-id="9437603207-157">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +					    </span><span class="nc">filename</span><span class="p">:</span><span class="nf">basename</span><span class="p" data-group-id="9437603207-158">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9437603207-158">)</span><span class="p" data-group-id="9437603207-157">]</span><span class="p" data-group-id="9437603207-156">)</span><span class="p" data-group-id="9437603207-155">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% LOCALS</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% make_script(RelFileName,Opts)</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │ -</span><span class="nf">make_script</span><span class="p" data-group-id="6359730344-159">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="6359730344-159">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="6359730344-160">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-161">[</span><span class="ss">no_module_tests</span><span class="p">,</span><span class="w">
│ │ │ │ -				       </span><span class="p" data-group-id="6359730344-162">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="6359730344-163">(</span><span class="n">RelFileName</span><span class="p" data-group-id="6359730344-163">)</span><span class="p" data-group-id="6359730344-162">}</span><span class="w">
│ │ │ │ -				       </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="6359730344-161">]</span><span class="p" data-group-id="6359730344-160">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">make_script</span><span class="p" data-group-id="9437603207-159">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="9437603207-159">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="9437603207-160">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-161">[</span><span class="ss">no_module_tests</span><span class="p">,</span><span class="w">
│ │ │ │ +				       </span><span class="p" data-group-id="9437603207-162">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="9437603207-163">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9437603207-163">)</span><span class="p" data-group-id="9437603207-162">}</span><span class="w">
│ │ │ │ +				       </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="9437603207-161">]</span><span class="p" data-group-id="9437603207-160">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% make_tar(RelFileName,Opts)</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │ -</span><span class="nf">make_tar</span><span class="p" data-group-id="6359730344-164">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="6359730344-164">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">RootDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">code</span><span class="p">:</span><span class="nf">root_dir</span><span class="p" data-group-id="6359730344-165">(</span><span class="p" data-group-id="6359730344-165">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="6359730344-166">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-167">[</span><span class="p" data-group-id="6359730344-168">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="6359730344-168">}</span><span class="p">,</span><span class="w">
│ │ │ │ -				    </span><span class="p" data-group-id="6359730344-169">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="6359730344-170">(</span><span class="n">RelFileName</span><span class="p" data-group-id="6359730344-170">)</span><span class="p" data-group-id="6359730344-169">}</span><span class="w">
│ │ │ │ -				    </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="6359730344-167">]</span><span class="p" data-group-id="6359730344-166">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">make_tar</span><span class="p" data-group-id="9437603207-164">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="9437603207-164">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">RootDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">code</span><span class="p">:</span><span class="nf">root_dir</span><span class="p" data-group-id="9437603207-165">(</span><span class="p" data-group-id="9437603207-165">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="9437603207-166">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-167">[</span><span class="p" data-group-id="9437603207-168">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9437603207-168">}</span><span class="p">,</span><span class="w">
│ │ │ │ +				    </span><span class="p" data-group-id="9437603207-169">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="9437603207-170">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9437603207-170">)</span><span class="p" data-group-id="9437603207-169">}</span><span class="w">
│ │ │ │ +				    </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="9437603207-167">]</span><span class="p" data-group-id="9437603207-166">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% extract_tar(TarFile, DestDir)</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │ -</span><span class="nf">extract_tar</span><span class="p" data-group-id="6359730344-171">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="6359730344-171">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">extract</span><span class="p" data-group-id="6359730344-172">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-173">[</span><span class="p" data-group-id="6359730344-174">{</span><span class="ss">cwd</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="6359730344-174">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="6359730344-173">]</span><span class="p" data-group-id="6359730344-172">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">extract_tar</span><span class="p" data-group-id="9437603207-171">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="9437603207-171">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">extract</span><span class="p" data-group-id="9437603207-172">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-173">[</span><span class="p" data-group-id="9437603207-174">{</span><span class="ss">cwd</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="9437603207-174">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="9437603207-173">]</span><span class="p" data-group-id="9437603207-172">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="6359730344-175">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="6359730344-175">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="6359730344-176">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p" data-group-id="6359730344-176">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="9437603207-175">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="9437603207-175">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="9437603207-176">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p" data-group-id="9437603207-176">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="6359730344-177">(</span><span class="n">Scripts</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-177">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="6359730344-178">(</span><span class="nf">fun</span><span class="p" data-group-id="6359730344-179">(</span><span class="n">Script</span><span class="p" data-group-id="6359730344-179">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                          </span><span class="nf">subst_src_script</span><span class="p" data-group-id="6359730344-180">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w">
│ │ │ │ -                                           </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-180">)</span><span class="w">
│ │ │ │ -                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Scripts</span><span class="p" data-group-id="6359730344-178">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">subst_src_script</span><span class="p" data-group-id="6359730344-181">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-181">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst_file</span><span class="p" data-group-id="6359730344-182">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-183">(</span><span class="p" data-group-id="6359730344-184">[</span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.src&quot;</span><span class="p" data-group-id="6359730344-184">]</span><span class="p" data-group-id="6359730344-183">)</span><span class="p">,</span><span class="w">
│ │ │ │ -               </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-185">(</span><span class="p" data-group-id="6359730344-186">[</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="p" data-group-id="6359730344-186">]</span><span class="p" data-group-id="6359730344-185">)</span><span class="p">,</span><span class="w">
│ │ │ │ -               </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-182">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">subst_file</span><span class="p" data-group-id="6359730344-187">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-187">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-188">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="6359730344-188">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="6359730344-189">(</span><span class="n">Src</span><span class="p" data-group-id="6359730344-189">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">NConts</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">subst</span><span class="p" data-group-id="6359730344-190">(</span><span class="n">Conts</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="6359730344-190">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">write_file</span><span class="p" data-group-id="6359730344-191">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">NConts</span><span class="p" data-group-id="6359730344-191">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="6359730344-192">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-192">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="9437603207-177">(</span><span class="n">Scripts</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-177">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="9437603207-178">(</span><span class="nf">fun</span><span class="p" data-group-id="9437603207-179">(</span><span class="n">Script</span><span class="p" data-group-id="9437603207-179">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                          </span><span class="nf">subst_src_script</span><span class="p" data-group-id="9437603207-180">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w">
│ │ │ │ +                                           </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-180">)</span><span class="w">
│ │ │ │ +                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Scripts</span><span class="p" data-group-id="9437603207-178">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">subst_src_script</span><span class="p" data-group-id="9437603207-181">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-181">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst_file</span><span class="p" data-group-id="9437603207-182">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-183">(</span><span class="p" data-group-id="9437603207-184">[</span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.src&quot;</span><span class="p" data-group-id="9437603207-184">]</span><span class="p" data-group-id="9437603207-183">)</span><span class="p">,</span><span class="w">
│ │ │ │ +               </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-185">(</span><span class="p" data-group-id="9437603207-186">[</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="p" data-group-id="9437603207-186">]</span><span class="p" data-group-id="9437603207-185">)</span><span class="p">,</span><span class="w">
│ │ │ │ +               </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-182">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">subst_file</span><span class="p" data-group-id="9437603207-187">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-187">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-188">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="9437603207-188">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="9437603207-189">(</span><span class="n">Src</span><span class="p" data-group-id="9437603207-189">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">NConts</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">subst</span><span class="p" data-group-id="9437603207-190">(</span><span class="n">Conts</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="9437603207-190">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">write_file</span><span class="p" data-group-id="9437603207-191">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">NConts</span><span class="p" data-group-id="9437603207-191">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="9437603207-192">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-192">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6359730344-193">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="6359730344-193">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="6359730344-194">(</span><span class="n">Src</span><span class="p" data-group-id="6359730344-194">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="6359730344-195">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="6359730344-195">)</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9437603207-193">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9437603207-193">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="9437603207-194">(</span><span class="n">Src</span><span class="p" data-group-id="9437603207-194">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="9437603207-195">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9437603207-195">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">ok</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%% subst(Str, Vars)</span><span class="w">
│ │ │ │  </span><span class="c1">%% Vars = [{Var, Val}]</span><span class="w">
│ │ │ │  </span><span class="c1">%% Var = Val = string()</span><span class="w">
│ │ │ │  </span><span class="c1">%% Substitute all occurrences of %Var% for Val in Str, using the list</span><span class="w">
│ │ │ │  </span><span class="c1">%% of variables in Vars.</span><span class="w">
│ │ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="6359730344-196">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="6359730344-196">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst</span><span class="p" data-group-id="6359730344-197">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-198">[</span><span class="p" data-group-id="6359730344-198">]</span><span class="p" data-group-id="6359730344-197">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9437603207-196">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="9437603207-196">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst</span><span class="p" data-group-id="9437603207-197">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-198">[</span><span class="p" data-group-id="9437603207-198">]</span><span class="p" data-group-id="9437603207-197">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="6359730344-199">(</span><span class="p" data-group-id="6359730344-200">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-200">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-199">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$Z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="6359730344-201">(</span><span class="p" data-group-id="6359730344-202">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-202">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-203">[</span><span class="p" data-group-id="6359730344-203">]</span><span class="p" data-group-id="6359730344-201">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="6359730344-204">(</span><span class="p" data-group-id="6359730344-205">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-205">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-204">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="6359730344-206">(</span><span class="p" data-group-id="6359730344-207">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-207">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-208">[</span><span class="p" data-group-id="6359730344-208">]</span><span class="p" data-group-id="6359730344-206">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="6359730344-209">(</span><span class="p" data-group-id="6359730344-210">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-210">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-209">)</span><span class="w"> </span><span class="k">when</span><span class="w">  </span><span class="n">C</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="sc">$_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="6359730344-211">(</span><span class="p" data-group-id="6359730344-212">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-212">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-213">[</span><span class="p" data-group-id="6359730344-213">]</span><span class="p" data-group-id="6359730344-211">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="6359730344-214">(</span><span class="p" data-group-id="6359730344-215">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-215">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-214">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst</span><span class="p" data-group-id="6359730344-216">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-217">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-217">]</span><span class="p" data-group-id="6359730344-216">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="6359730344-218">(</span><span class="p" data-group-id="6359730344-219">[</span><span class="p" data-group-id="6359730344-219">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-218">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="6359730344-220">(</span><span class="n">Result</span><span class="p" data-group-id="6359730344-220">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">subst_var</span><span class="p" data-group-id="6359730344-221">(</span><span class="p" data-group-id="6359730344-222">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-222">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="6359730344-221">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Key</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="6359730344-223">(</span><span class="n">VarAcc</span><span class="p" data-group-id="6359730344-223">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="6359730344-224">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="6359730344-224">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6359730344-225">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-226">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="6359730344-226">}</span><span class="p" data-group-id="6359730344-225">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">subst</span><span class="p" data-group-id="6359730344-227">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="6359730344-228">(</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-228">)</span><span class="p" data-group-id="6359730344-227">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9437603207-199">(</span><span class="p" data-group-id="9437603207-200">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-200">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-199">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$Z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9437603207-201">(</span><span class="p" data-group-id="9437603207-202">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-202">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-203">[</span><span class="p" data-group-id="9437603207-203">]</span><span class="p" data-group-id="9437603207-201">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9437603207-204">(</span><span class="p" data-group-id="9437603207-205">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-205">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-204">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9437603207-206">(</span><span class="p" data-group-id="9437603207-207">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-207">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-208">[</span><span class="p" data-group-id="9437603207-208">]</span><span class="p" data-group-id="9437603207-206">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9437603207-209">(</span><span class="p" data-group-id="9437603207-210">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-210">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-209">)</span><span class="w"> </span><span class="k">when</span><span class="w">  </span><span class="n">C</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="sc">$_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9437603207-211">(</span><span class="p" data-group-id="9437603207-212">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-212">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-213">[</span><span class="p" data-group-id="9437603207-213">]</span><span class="p" data-group-id="9437603207-211">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9437603207-214">(</span><span class="p" data-group-id="9437603207-215">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-215">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-214">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst</span><span class="p" data-group-id="9437603207-216">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-217">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-217">]</span><span class="p" data-group-id="9437603207-216">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9437603207-218">(</span><span class="p" data-group-id="9437603207-219">[</span><span class="p" data-group-id="9437603207-219">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-218">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9437603207-220">(</span><span class="n">Result</span><span class="p" data-group-id="9437603207-220">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">subst_var</span><span class="p" data-group-id="9437603207-221">(</span><span class="p" data-group-id="9437603207-222">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-222">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9437603207-221">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Key</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9437603207-223">(</span><span class="n">VarAcc</span><span class="p" data-group-id="9437603207-223">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="9437603207-224">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="9437603207-224">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="9437603207-225">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-226">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="9437603207-226">}</span><span class="p" data-group-id="9437603207-225">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">subst</span><span class="p" data-group-id="9437603207-227">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9437603207-228">(</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-228">)</span><span class="p" data-group-id="9437603207-227">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">subst</span><span class="p" data-group-id="6359730344-229">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-230">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6359730344-231">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-231">]</span><span class="p" data-group-id="6359730344-230">]</span><span class="p" data-group-id="6359730344-229">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">subst</span><span class="p" data-group-id="9437603207-229">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-230">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9437603207-231">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-231">]</span><span class="p" data-group-id="9437603207-230">]</span><span class="p" data-group-id="9437603207-229">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">subst_var</span><span class="p" data-group-id="6359730344-232">(</span><span class="p" data-group-id="6359730344-233">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6359730344-233">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="6359730344-232">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="6359730344-234">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-235">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="6359730344-235">]</span><span class="p" data-group-id="6359730344-234">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">subst_var</span><span class="p" data-group-id="6359730344-236">(</span><span class="p" data-group-id="6359730344-237">[</span><span class="p" data-group-id="6359730344-237">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="6359730344-236">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">subst</span><span class="p" data-group-id="6359730344-238">(</span><span class="p" data-group-id="6359730344-239">[</span><span class="p" data-group-id="6359730344-239">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-240">[</span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6359730344-241">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6359730344-241">]</span><span class="p" data-group-id="6359730344-240">]</span><span class="p" data-group-id="6359730344-238">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">copy_file</span><span class="p" data-group-id="6359730344-242">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="6359730344-242">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="6359730344-243">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-244">[</span><span class="p" data-group-id="6359730344-244">]</span><span class="p" data-group-id="6359730344-243">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">copy_file</span><span class="p" data-group-id="6359730344-245">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-245">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-246">{</span><span class="ss">ok</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6359730344-246">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">copy</span><span class="p" data-group-id="6359730344-247">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="6359730344-247">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="6359730344-248">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="6359730344-248">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">subst_var</span><span class="p" data-group-id="9437603207-232">(</span><span class="p" data-group-id="9437603207-233">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9437603207-233">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9437603207-232">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9437603207-234">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-235">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9437603207-235">]</span><span class="p" data-group-id="9437603207-234">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">subst_var</span><span class="p" data-group-id="9437603207-236">(</span><span class="p" data-group-id="9437603207-237">[</span><span class="p" data-group-id="9437603207-237">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9437603207-236">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">subst</span><span class="p" data-group-id="9437603207-238">(</span><span class="p" data-group-id="9437603207-239">[</span><span class="p" data-group-id="9437603207-239">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-240">[</span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9437603207-241">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9437603207-241">]</span><span class="p" data-group-id="9437603207-240">]</span><span class="p" data-group-id="9437603207-238">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">copy_file</span><span class="p" data-group-id="9437603207-242">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="9437603207-242">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9437603207-243">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-244">[</span><span class="p" data-group-id="9437603207-244">]</span><span class="p" data-group-id="9437603207-243">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">copy_file</span><span class="p" data-group-id="9437603207-245">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-245">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-246">{</span><span class="ss">ok</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9437603207-246">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">copy</span><span class="p" data-group-id="9437603207-247">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="9437603207-247">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="9437603207-248">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9437603207-248">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="6359730344-249">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="6359730344-249">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="6359730344-250">(</span><span class="n">Src</span><span class="p" data-group-id="6359730344-250">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="6359730344-251">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="6359730344-251">)</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="9437603207-249">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9437603207-249">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="9437603207-250">(</span><span class="n">Src</span><span class="p" data-group-id="9437603207-250">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="9437603207-251">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9437603207-251">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">ok</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">write_file</span><span class="p" data-group-id="6359730344-252">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="6359730344-252">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Enc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">native_name_encoding</span><span class="p" data-group-id="6359730344-253">(</span><span class="p" data-group-id="6359730344-253">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-254">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="6359730344-254">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="6359730344-255">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-256">[</span><span class="ss">write</span><span class="p" data-group-id="6359730344-256">]</span><span class="p" data-group-id="6359730344-255">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">write</span><span class="p" data-group-id="6359730344-257">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="nc">unicode</span><span class="p">:</span><span class="nf">characters_to_binary</span><span class="p" data-group-id="6359730344-258">(</span><span class="n">Conts</span><span class="p">,</span><span class="n">Enc</span><span class="p">,</span><span class="n">Enc</span><span class="p" data-group-id="6359730344-258">)</span><span class="p" data-group-id="6359730344-257">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="6359730344-259">(</span><span class="n">Fd</span><span class="p" data-group-id="6359730344-259">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">read_txt_file</span><span class="p" data-group-id="6359730344-260">(</span><span class="n">File</span><span class="p" data-group-id="6359730344-260">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-261">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="6359730344-261">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file</span><span class="p" data-group-id="6359730344-262">(</span><span class="n">File</span><span class="p" data-group-id="6359730344-262">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6359730344-263">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_list</span><span class="p" data-group-id="6359730344-264">(</span><span class="n">Bin</span><span class="p" data-group-id="6359730344-264">)</span><span class="p" data-group-id="6359730344-263">}</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="6359730344-265">(</span><span class="n">Dir</span><span class="p" data-group-id="6359730344-265">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">remove_all_files</span><span class="p" data-group-id="6359730344-266">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6359730344-267">[</span><span class="n">Dir</span><span class="p" data-group-id="6359730344-267">]</span><span class="p" data-group-id="6359730344-266">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">remove_all_files</span><span class="p" data-group-id="6359730344-268">(</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="6359730344-268">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="6359730344-269">(</span><span class="nf">fun</span><span class="p" data-group-id="6359730344-270">(</span><span class="n">File</span><span class="p" data-group-id="6359730344-270">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                          </span><span class="n">FilePath</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="6359730344-271">(</span><span class="p" data-group-id="6359730344-272">[</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">File</span><span class="p" data-group-id="6359730344-272">]</span><span class="p" data-group-id="6359730344-271">)</span><span class="p">,</span><span class="w">
│ │ │ │ -                          </span><span class="k">case</span><span class="w"> </span><span class="nc">filelib</span><span class="p">:</span><span class="nf">is_dir</span><span class="p" data-group-id="6359730344-273">(</span><span class="n">FilePath</span><span class="p" data-group-id="6359730344-273">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">write_file</span><span class="p" data-group-id="9437603207-252">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="9437603207-252">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Enc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">native_name_encoding</span><span class="p" data-group-id="9437603207-253">(</span><span class="p" data-group-id="9437603207-253">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-254">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="9437603207-254">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="9437603207-255">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-256">[</span><span class="ss">write</span><span class="p" data-group-id="9437603207-256">]</span><span class="p" data-group-id="9437603207-255">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">write</span><span class="p" data-group-id="9437603207-257">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="nc">unicode</span><span class="p">:</span><span class="nf">characters_to_binary</span><span class="p" data-group-id="9437603207-258">(</span><span class="n">Conts</span><span class="p">,</span><span class="n">Enc</span><span class="p">,</span><span class="n">Enc</span><span class="p" data-group-id="9437603207-258">)</span><span class="p" data-group-id="9437603207-257">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9437603207-259">(</span><span class="n">Fd</span><span class="p" data-group-id="9437603207-259">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">read_txt_file</span><span class="p" data-group-id="9437603207-260">(</span><span class="n">File</span><span class="p" data-group-id="9437603207-260">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-261">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="9437603207-261">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file</span><span class="p" data-group-id="9437603207-262">(</span><span class="n">File</span><span class="p" data-group-id="9437603207-262">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9437603207-263">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_list</span><span class="p" data-group-id="9437603207-264">(</span><span class="n">Bin</span><span class="p" data-group-id="9437603207-264">)</span><span class="p" data-group-id="9437603207-263">}</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="9437603207-265">(</span><span class="n">Dir</span><span class="p" data-group-id="9437603207-265">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">remove_all_files</span><span class="p" data-group-id="9437603207-266">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9437603207-267">[</span><span class="n">Dir</span><span class="p" data-group-id="9437603207-267">]</span><span class="p" data-group-id="9437603207-266">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">remove_all_files</span><span class="p" data-group-id="9437603207-268">(</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="9437603207-268">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="9437603207-269">(</span><span class="nf">fun</span><span class="p" data-group-id="9437603207-270">(</span><span class="n">File</span><span class="p" data-group-id="9437603207-270">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                          </span><span class="n">FilePath</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9437603207-271">(</span><span class="p" data-group-id="9437603207-272">[</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">File</span><span class="p" data-group-id="9437603207-272">]</span><span class="p" data-group-id="9437603207-271">)</span><span class="p">,</span><span class="w">
│ │ │ │ +                          </span><span class="k">case</span><span class="w"> </span><span class="nc">filelib</span><span class="p">:</span><span class="nf">is_dir</span><span class="p" data-group-id="9437603207-273">(</span><span class="n">FilePath</span><span class="p" data-group-id="9437603207-273">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │                                </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                                  </span><span class="p" data-group-id="6359730344-274">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="6359730344-274">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">list_dir</span><span class="p" data-group-id="6359730344-275">(</span><span class="n">FilePath</span><span class="p" data-group-id="6359730344-275">)</span><span class="p">,</span><span class="w">
│ │ │ │ -                                  </span><span class="nf">remove_all_files</span><span class="p" data-group-id="6359730344-276">(</span><span class="n">FilePath</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="6359730344-276">)</span><span class="p">,</span><span class="w">
│ │ │ │ -                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">del_dir</span><span class="p" data-group-id="6359730344-277">(</span><span class="n">FilePath</span><span class="p" data-group-id="6359730344-277">)</span><span class="p">;</span><span class="w">
│ │ │ │ +                                  </span><span class="p" data-group-id="9437603207-274">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="9437603207-274">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">list_dir</span><span class="p" data-group-id="9437603207-275">(</span><span class="n">FilePath</span><span class="p" data-group-id="9437603207-275">)</span><span class="p">,</span><span class="w">
│ │ │ │ +                                  </span><span class="nf">remove_all_files</span><span class="p" data-group-id="9437603207-276">(</span><span class="n">FilePath</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="9437603207-276">)</span><span class="p">,</span><span class="w">
│ │ │ │ +                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">del_dir</span><span class="p" data-group-id="9437603207-277">(</span><span class="n">FilePath</span><span class="p" data-group-id="9437603207-277">)</span><span class="p">;</span><span class="w">
│ │ │ │                                </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="6359730344-278">(</span><span class="n">FilePath</span><span class="p" data-group-id="6359730344-278">)</span><span class="w">
│ │ │ │ +                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="9437603207-278">(</span><span class="n">FilePath</span><span class="p" data-group-id="9437603207-278">)</span><span class="w">
│ │ │ │                            </span><span class="k">end</span><span class="w">
│ │ │ │ -                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="6359730344-269">)</span><span class="p">.</span></code></pre>
│ │ │ │ +                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="9437603207-269">)</span><span class="p">.</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/content.opf
│ │ │ │ ├── OEBPS/content.opf
│ │ │ │ │ @@ -1,14 +1,14 @@
│ │ │ │ │  <?xml version="1.0" encoding="utf-8"?>
│ │ │ │ │  <package xmlns="http://www.idpf.org/2007/opf" unique-identifier="project-Erlang System Documentation" version="3.0">
│ │ │ │ │    <metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
│ │ │ │ │      <dc:title>Erlang System Documentation - 27.3.4.4</dc:title>
│ │ │ │ │ -    <dc:identifier id="project-Erlang System Documentation">urn:uuid:9247ffe1-d5e2-0701-dd1e-8e8e9ce19238</dc:identifier>
│ │ │ │ │ +    <dc:identifier id="project-Erlang System Documentation">urn:uuid:b32d59b5-e8ac-7627-6f43-c0eb6f420682</dc:identifier>
│ │ │ │ │      <dc:language>en</dc:language>
│ │ │ │ │ -    <meta property="dcterms:modified">2025-10-31T13:18:13Z</meta>
│ │ │ │ │ +    <meta property="dcterms:modified">2025-10-31T15:24:14Z</meta>
│ │ │ │ │    </metadata>
│ │ │ │ │    <manifest>
│ │ │ │ │      <item id="nav" href="nav.xhtml" media-type="application/xhtml+xml" properties="nav scripted"/>
│ │ │ │ │      <item id="cover" href="title.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="readme" href="readme.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="installation_guide" href="installation_guide.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="install" href="install.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │ @@ -82,21 +82,21 @@
│ │ │ │ │      <item id="c_portdriver" href="c_portdriver.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="cnode" href="cnode.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="nif" href="nif.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="debugging" href="debugging.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="embedded" href="embedded.xhtml" media-type="application/xhtml+xml" properties="scripted"/>
│ │ │ │ │      <item id="epub-lsjciytm-js" href="dist/epub-LSJCIYTM.js" media-type="text/javascript"/>
│ │ │ │ │      <item id="epub-erlang-espt6bqv-css" href="dist/epub-erlang-ESPT6BQV.css" media-type="text/css"/>
│ │ │ │ │ +    <item id="dist2-gif" href="assets/dist2.gif" media-type="image/gif"/>
│ │ │ │ │      <item id="erlang-logo-png" href="assets/erlang-logo.png" media-type="image/png"/>
│ │ │ │ │      <item id="dist1-gif" href="assets/dist1.gif" media-type="image/gif"/>
│ │ │ │ │ -    <item id="dist2-gif" href="assets/dist2.gif" media-type="image/gif"/>
│ │ │ │ │      <item id="dist3-gif" href="assets/dist3.gif" media-type="image/gif"/>
│ │ │ │ │      <item id="dist4-gif" href="assets/dist4.gif" media-type="image/gif"/>
│ │ │ │ │ -    <item id="dist5-gif" href="assets/dist5.gif" media-type="image/gif"/>
│ │ │ │ │      <item id="ballpoint-pen-svg" href="assets/ballpoint-pen.svg" media-type="image/svg+xml"/>
│ │ │ │ │ +    <item id="dist5-gif" href="assets/dist5.gif" media-type="image/gif"/>
│ │ │ │ │      <item id="logo" href="assets/logo.png" media-type="image/png"/>
│ │ │ │ │    </manifest>
│ │ │ │ │    <spine>
│ │ │ │ │      <itemref idref="cover"/>
│ │ │ │ │      <itemref idref="nav"/>
│ │ │ │ │      <itemref idref="readme"/>
│ │ │ │ │      <itemref idref="installation_guide"/>
│ │ │ ├── OEBPS/conc_prog.xhtml
│ │ │ │ @@ -37,107 +37,107 @@
│ │ │ │  threads of execution in an Erlang program and to allow these threads to
│ │ │ │  communicate with each other. In Erlang, each thread of execution is called a
│ │ │ │  <em>process</em>.</p><p>(Aside: the term &quot;process&quot; is usually used when the threads of execution share
│ │ │ │  no data with each other and the term &quot;thread&quot; when they share data in some way.
│ │ │ │  Threads of execution in Erlang share no data, that is why they are called
│ │ │ │  processes).</p><p>The Erlang BIF <code class="inline">spawn</code> is used to create a new process:
│ │ │ │  <code class="inline">spawn(Module, Exported_Function, List of Arguments)</code>. Consider the following
│ │ │ │ -module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3030495588-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="3030495588-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7138979052-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="7138979052-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3030495588-2">(</span><span class="p" data-group-id="3030495588-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3030495588-3">]</span><span class="p" data-group-id="3030495588-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7138979052-2">(</span><span class="p" data-group-id="7138979052-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7138979052-3">]</span><span class="p" data-group-id="7138979052-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">say_something</span><span class="p" data-group-id="3030495588-4">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3030495588-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">say_something</span><span class="p" data-group-id="7138979052-4">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7138979052-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">done</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">say_something</span><span class="p" data-group-id="3030495588-5">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="p" data-group-id="3030495588-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3030495588-6">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3030495588-7">[</span><span class="n">What</span><span class="p" data-group-id="3030495588-7">]</span><span class="p" data-group-id="3030495588-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">say_something</span><span class="p" data-group-id="3030495588-8">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3030495588-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="3030495588-9">(</span><span class="p" data-group-id="3030495588-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="3030495588-10">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3030495588-11">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="3030495588-11">]</span><span class="p" data-group-id="3030495588-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="3030495588-12">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3030495588-13">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="3030495588-13">]</span><span class="p" data-group-id="3030495588-12">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="9055951526-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="9055951526-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="9055951526-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut14</span><span class="p" data-group-id="9055951526-2">}</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">say_something</span><span class="p" data-group-id="9055951526-3">(</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="9055951526-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">say_something</span><span class="p" data-group-id="7138979052-5">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="p" data-group-id="7138979052-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7138979052-6">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7138979052-7">[</span><span class="n">What</span><span class="p" data-group-id="7138979052-7">]</span><span class="p" data-group-id="7138979052-6">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">say_something</span><span class="p" data-group-id="7138979052-8">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7138979052-8">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="7138979052-9">(</span><span class="p" data-group-id="7138979052-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7138979052-10">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7138979052-11">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7138979052-11">]</span><span class="p" data-group-id="7138979052-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7138979052-12">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7138979052-13">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7138979052-13">]</span><span class="p" data-group-id="7138979052-12">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="0158721727-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="0158721727-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0158721727-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut14</span><span class="p" data-group-id="0158721727-2">}</span><span class="gp unselectable">
│ │ │ │ +6&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">say_something</span><span class="p" data-group-id="0158721727-3">(</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="0158721727-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │ │  </span><span class="ss">done</span></code></pre><p>As shown, the function <code class="inline">say_something</code> writes its first argument the number of
│ │ │ │  times specified by second argument. The function <code class="inline">start</code> starts two Erlang
│ │ │ │  processes, one that writes &quot;hello&quot; three times and one that writes &quot;goodbye&quot;
│ │ │ │  three times. Both processes use the function <code class="inline">say_something</code>. Notice that a
│ │ │ │  function used in this way by <code class="inline">spawn</code>, to start a process, must be exported from
│ │ │ │ -the module (that is, in the <code class="inline">-export</code> at the start of the module).</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="8459686315-1">(</span><span class="p" data-group-id="8459686315-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +the module (that is, in the <code class="inline">-export</code> at the start of the module).</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9503069889-1">(</span><span class="p" data-group-id="9503069889-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │ │  </span><span class="ss">goodbye</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.63</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │ │  </span><span class="ss">goodbye</span><span class="w">
│ │ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │ │  </span><span class="ss">goodbye</span></code></pre><p>Notice that it did not write &quot;hello&quot; three times and then &quot;goodbye&quot; three times.
│ │ │ │  Instead, the first process wrote a &quot;hello&quot;, the second a &quot;goodbye&quot;, the first
│ │ │ │  another &quot;hello&quot; and so forth. But where did the <code class="inline">&lt;0.63.0&gt;</code> come from? The return
│ │ │ │  value of a function is the return value of the last &quot;thing&quot; in the function. The
│ │ │ │ -last thing in the function <code class="inline">start</code> is</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="2035178905-1">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2035178905-2">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="2035178905-2">]</span><span class="p" data-group-id="2035178905-1">)</span><span class="p">.</span></code></pre><p><code class="inline">spawn</code> returns a <em>process identifier</em>, or <em>pid</em>, which uniquely identifies the
│ │ │ │ +last thing in the function <code class="inline">start</code> is</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="1792033055-1">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1792033055-2">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1792033055-2">]</span><span class="p" data-group-id="1792033055-1">)</span><span class="p">.</span></code></pre><p><code class="inline">spawn</code> returns a <em>process identifier</em>, or <em>pid</em>, which uniquely identifies the
│ │ │ │  process. So <code class="inline">&lt;0.63.0&gt;</code> is the pid of the <code class="inline">spawn</code> function call above. The next
│ │ │ │  example shows how to use pids.</p><p>Notice also that ~p is used instead of ~w in <a href="../../../lib/stdlib/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a>. To quote <a href="../../../lib/stdlib/doc/html/io.html#tilde_p">the manual</a>:</p><blockquote><p>~p Writes the data with standard syntax in the same way as ~w, but breaks terms
│ │ │ │  whose printed representation is longer than one line into many lines and indents
│ │ │ │  each line sensibly. It also tries to detect flat lists of printable characters and
│ │ │ │  to output these as strings</p></blockquote><h2 id="message-passing" class="section-heading">
│ │ │ │    <a href="#message-passing" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Message Passing</span>
│ │ │ │  </h2>
│ │ │ │  <p>In the following example two processes are created and they send messages to
│ │ │ │ -each other a number of times.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3988347830-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="3988347830-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +each other a number of times.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8786204162-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="8786204162-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3988347830-2">(</span><span class="p" data-group-id="3988347830-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3988347830-3">]</span><span class="p" data-group-id="3988347830-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8786204162-2">(</span><span class="p" data-group-id="8786204162-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8786204162-3">]</span><span class="p" data-group-id="8786204162-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="3988347830-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="3988347830-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="8786204162-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8786204162-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3988347830-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3988347830-6">[</span><span class="p" data-group-id="3988347830-6">]</span><span class="p" data-group-id="3988347830-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8786204162-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786204162-6">[</span><span class="p" data-group-id="8786204162-6">]</span><span class="p" data-group-id="8786204162-5">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="3988347830-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="3988347830-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3988347830-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3988347830-9">(</span><span class="p" data-group-id="3988347830-9">)</span><span class="p" data-group-id="3988347830-8">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="8786204162-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8786204162-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8786204162-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8786204162-9">(</span><span class="p" data-group-id="8786204162-9">)</span><span class="p" data-group-id="8786204162-8">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3988347830-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3988347830-11">[</span><span class="p" data-group-id="3988347830-11">]</span><span class="p" data-group-id="3988347830-10">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8786204162-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786204162-11">[</span><span class="p" data-group-id="8786204162-11">]</span><span class="p" data-group-id="8786204162-10">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="3988347830-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="3988347830-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="8786204162-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8786204162-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="3988347830-13">(</span><span class="p" data-group-id="3988347830-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="8786204162-13">(</span><span class="p" data-group-id="8786204162-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3988347830-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3988347830-15">[</span><span class="p" data-group-id="3988347830-15">]</span><span class="p" data-group-id="3988347830-14">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="3988347830-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="3988347830-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3988347830-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3988347830-18">[</span><span class="p" data-group-id="3988347830-18">]</span><span class="p" data-group-id="3988347830-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8786204162-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786204162-15">[</span><span class="p" data-group-id="8786204162-15">]</span><span class="p" data-group-id="8786204162-14">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8786204162-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="8786204162-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8786204162-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786204162-18">[</span><span class="p" data-group-id="8786204162-18">]</span><span class="p" data-group-id="8786204162-17">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="3988347830-19">(</span><span class="p" data-group-id="3988347830-19">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="8786204162-19">(</span><span class="p" data-group-id="8786204162-19">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="3988347830-20">(</span><span class="p" data-group-id="3988347830-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="3988347830-21">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3988347830-22">[</span><span class="p" data-group-id="3988347830-22">]</span><span class="p" data-group-id="3988347830-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="3988347830-23">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3988347830-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="3988347830-24">]</span><span class="p" data-group-id="3988347830-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">c</span><span class="p" data-group-id="3788598045-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="3788598045-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3788598045-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut15</span><span class="p" data-group-id="3788598045-2">}</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">tut15</span><span class="p">:</span><span class="w"> </span><span class="nf">start</span><span class="p" data-group-id="3788598045-3">(</span><span class="p" data-group-id="3788598045-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="8786204162-20">(</span><span class="p" data-group-id="8786204162-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="8786204162-21">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786204162-22">[</span><span class="p" data-group-id="8786204162-22">]</span><span class="p" data-group-id="8786204162-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="8786204162-23">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786204162-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8786204162-24">]</span><span class="p" data-group-id="8786204162-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">c</span><span class="p" data-group-id="8181779633-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="8181779633-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8181779633-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut15</span><span class="p" data-group-id="8181779633-2">}</span><span class="gp unselectable">
│ │ │ │ +2&gt; </span><span class="nc">tut15</span><span class="p">:</span><span class="w"> </span><span class="nf">start</span><span class="p" data-group-id="8181779633-3">(</span><span class="p" data-group-id="8181779633-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.36</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="ss">ping</span><span class="w"> </span><span class="ss">finished</span><span class="w">
│ │ │ │ -</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>The function <code class="inline">start</code> first creates a process, let us call it &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1617349790-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1617349790-2">[</span><span class="p" data-group-id="1617349790-2">]</span><span class="p" data-group-id="1617349790-1">)</span></code></pre><p>This process executes <code class="inline">tut15:pong()</code>. <code class="inline">Pong_PID</code> is the process identity of the
│ │ │ │ -&quot;pong&quot; process. The function <code class="inline">start</code> now creates another process &quot;ping&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="4752932625-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4752932625-2">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4752932625-2">]</span><span class="p" data-group-id="4752932625-1">)</span><span class="p">,</span></code></pre><p>This process executes:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="8021843295-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8021843295-1">)</span></code></pre><p><code class="inline">&lt;0.36.0&gt;</code> is the return value from the <code class="inline">start</code> function.</p><p>The process &quot;pong&quot; now does:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │ +</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>The function <code class="inline">start</code> first creates a process, let us call it &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="2020418457-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2020418457-2">[</span><span class="p" data-group-id="2020418457-2">]</span><span class="p" data-group-id="2020418457-1">)</span></code></pre><p>This process executes <code class="inline">tut15:pong()</code>. <code class="inline">Pong_PID</code> is the process identity of the
│ │ │ │ +&quot;pong&quot; process. The function <code class="inline">start</code> now creates another process &quot;ping&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="9966064530-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9966064530-2">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="9966064530-2">]</span><span class="p" data-group-id="9966064530-1">)</span><span class="p">,</span></code></pre><p>This process executes:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="1121605136-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="1121605136-1">)</span></code></pre><p><code class="inline">&lt;0.36.0&gt;</code> is the return value from the <code class="inline">start</code> function.</p><p>The process &quot;pong&quot; now does:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │      </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7343589797-1">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7343589797-2">[</span><span class="p" data-group-id="7343589797-2">]</span><span class="p" data-group-id="7343589797-1">)</span><span class="p">;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="7343589797-3">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="7343589797-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7343589797-4">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7343589797-5">[</span><span class="p" data-group-id="7343589797-5">]</span><span class="p" data-group-id="7343589797-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5285674026-1">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5285674026-2">[</span><span class="p" data-group-id="5285674026-2">]</span><span class="p" data-group-id="5285674026-1">)</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5285674026-3">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="5285674026-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5285674026-4">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5285674026-5">[</span><span class="p" data-group-id="5285674026-5">]</span><span class="p" data-group-id="5285674026-4">)</span><span class="p">,</span><span class="w">
│ │ │ │          </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="nf">pong</span><span class="p" data-group-id="7343589797-6">(</span><span class="p" data-group-id="7343589797-6">)</span><span class="w">
│ │ │ │ +        </span><span class="nf">pong</span><span class="p" data-group-id="5285674026-6">(</span><span class="p" data-group-id="5285674026-6">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">receive</code> construct is used to allow processes to wait for messages from
│ │ │ │  other processes. It has the following format:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │     </span><span class="ss">pattern1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │         </span><span class="ss">actions1</span><span class="p">;</span><span class="w">
│ │ │ │     </span><span class="ss">pattern2</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │         </span><span class="ss">actions2</span><span class="p">;</span><span class="w">
│ │ │ │     </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ @@ -158,84 +158,84 @@
│ │ │ │  queue (keeping the first message and any other messages in the queue). If the
│ │ │ │  second message does not match, the third message is tried, and so on, until the
│ │ │ │  end of the queue is reached. If the end of the queue is reached, the process
│ │ │ │  blocks (stops execution) and waits until a new message is received and this
│ │ │ │  procedure is repeated.</p><p>The Erlang implementation is &quot;clever&quot; and minimizes the number of times each
│ │ │ │  message is tested against the patterns in each <code class="inline">receive</code>.</p><p>Now back to the ping pong example.</p><p>&quot;Pong&quot; is waiting for messages. If the atom <code class="inline">finished</code> is received, &quot;pong&quot;
│ │ │ │  writes &quot;Pong finished&quot; to the output and, as it has nothing more to do,
│ │ │ │ -terminates. If it receives a message with the format:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2864438964-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="2864438964-1">}</span></code></pre><p>it writes &quot;Pong received ping&quot; to the output and sends the atom <code class="inline">pong</code> to the
│ │ │ │ +terminates. If it receives a message with the format:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6779942560-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="6779942560-1">}</span></code></pre><p>it writes &quot;Pong received ping&quot; to the output and sends the atom <code class="inline">pong</code> to the
│ │ │ │  process &quot;ping&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span></code></pre><p>Notice how the operator &quot;!&quot; is used to send messages. The syntax of &quot;!&quot; is:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Message</span></code></pre><p>That is, <code class="inline">Message</code> (any Erlang term) is sent to the process with identity <code class="inline">Pid</code>.</p><p>After sending the message <code class="inline">pong</code> to the process &quot;ping&quot;, &quot;pong&quot; calls the <code class="inline">pong</code>
│ │ │ │  function again, which causes it to get back to the <code class="inline">receive</code> again and wait for
│ │ │ │ -another message.</p><p>Now let us look at the process &quot;ping&quot;. Recall that it was started by executing:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="9992621423-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="9992621423-1">)</span></code></pre><p>Looking at the function <code class="inline">ping/2</code>, the second clause of <code class="inline">ping/2</code> is executed
│ │ │ │ +another message.</p><p>Now let us look at the process &quot;ping&quot;. Recall that it was started by executing:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="4147407544-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4147407544-1">)</span></code></pre><p>Looking at the function <code class="inline">ping/2</code>, the second clause of <code class="inline">ping/2</code> is executed
│ │ │ │  since the value of the first argument is 3 (not 0) (first clause head is
│ │ │ │ -<code class="inline">ping(0,Pong_PID)</code>, second clause head is <code class="inline">ping(N,Pong_PID)</code>, so <code class="inline">N</code> becomes 3).</p><p>The second clause sends a message to &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9462131834-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="9462131834-2">(</span><span class="p" data-group-id="9462131834-2">)</span><span class="p" data-group-id="9462131834-1">}</span><span class="p">,</span></code></pre><p><a href="../../../lib/../erts/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a> returns the pid of the process that executes <a href="../../../lib/../erts/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a>, in this case the
│ │ │ │ +<code class="inline">ping(0,Pong_PID)</code>, second clause head is <code class="inline">ping(N,Pong_PID)</code>, so <code class="inline">N</code> becomes 3).</p><p>The second clause sends a message to &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6639917724-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6639917724-2">(</span><span class="p" data-group-id="6639917724-2">)</span><span class="p" data-group-id="6639917724-1">}</span><span class="p">,</span></code></pre><p><a href="../../../lib/../erts/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a> returns the pid of the process that executes <a href="../../../lib/../erts/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a>, in this case the
│ │ │ │  pid of &quot;ping&quot;. (Recall the code for &quot;pong&quot;, this lands up in the variable
│ │ │ │  <code class="inline">Ping_PID</code> in the <code class="inline">receive</code> previously explained.)</p><p>&quot;Ping&quot; now waits for a reply from &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ │      </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9033059450-1">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9033059450-2">[</span><span class="p" data-group-id="9033059450-2">]</span><span class="p" data-group-id="9033059450-1">)</span><span class="w">
│ │ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9405429995-1">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9405429995-2">[</span><span class="p" data-group-id="9405429995-2">]</span><span class="p" data-group-id="9405429995-1">)</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">,</span></code></pre><p>It writes &quot;Ping received pong&quot; when this reply arrives, after which &quot;ping&quot; calls
│ │ │ │ -the <code class="inline">ping</code> function again.</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="6734792110-1">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="6734792110-1">)</span></code></pre><p><code class="inline">N-1</code> causes the first argument to be decremented until it becomes 0. When this
│ │ │ │ -occurs, the first clause of <code class="inline">ping/2</code> is executed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="7968178834-1">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="7968178834-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +the <code class="inline">ping</code> function again.</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="0780695430-1">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="0780695430-1">)</span></code></pre><p><code class="inline">N-1</code> causes the first argument to be decremented until it becomes 0. When this
│ │ │ │ +occurs, the first clause of <code class="inline">ping/2</code> is executed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="4902213826-1">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4902213826-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w">  </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7968178834-2">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7968178834-3">[</span><span class="p" data-group-id="7968178834-3">]</span><span class="p" data-group-id="7968178834-2">)</span><span class="p">;</span></code></pre><p>The atom <code class="inline">finished</code> is sent to &quot;pong&quot; (causing it to terminate as described
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4902213826-2">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4902213826-3">[</span><span class="p" data-group-id="4902213826-3">]</span><span class="p" data-group-id="4902213826-2">)</span><span class="p">;</span></code></pre><p>The atom <code class="inline">finished</code> is sent to &quot;pong&quot; (causing it to terminate as described
│ │ │ │  above) and &quot;ping finished&quot; is written to the output. &quot;Ping&quot; then terminates as
│ │ │ │  it has nothing left to do.</p><h2 id="registered-process-names" class="section-heading">
│ │ │ │    <a href="#registered-process-names" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Registered Process Names</span>
│ │ │ │  </h2>
│ │ │ │  <p>In the above example, &quot;pong&quot; was first created to be able to give the identity
│ │ │ │  of &quot;pong&quot; when &quot;ping&quot; was started. That is, in some way &quot;ping&quot; must be able to
│ │ │ │  know the identity of &quot;pong&quot; to be able to send a message to it. Sometimes
│ │ │ │  processes which need to know each other's identities are started independently
│ │ │ │  of each other. Erlang thus provides a mechanism for processes to be given names
│ │ │ │  so that these names can be used as identities instead of pids. This is done by
│ │ │ │ -using the <code class="inline">register</code> BIF:</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="1820263141-1">(</span><span class="ss">some_atom</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="1820263141-1">)</span></code></pre><p>Let us now rewrite the ping pong example using this and give the name <code class="inline">pong</code> to
│ │ │ │ -the &quot;pong&quot; process:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0664512766-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="0664512766-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +using the <code class="inline">register</code> BIF:</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="8246205917-1">(</span><span class="ss">some_atom</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="8246205917-1">)</span></code></pre><p>Let us now rewrite the ping pong example using this and give the name <code class="inline">pong</code> to
│ │ │ │ +the &quot;pong&quot; process:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9190214226-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="9190214226-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0664512766-2">(</span><span class="p" data-group-id="0664512766-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0664512766-3">]</span><span class="p" data-group-id="0664512766-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9190214226-2">(</span><span class="p" data-group-id="9190214226-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9190214226-3">]</span><span class="p" data-group-id="9190214226-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="0664512766-4">(</span><span class="mi">0</span><span class="p" data-group-id="0664512766-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="9190214226-4">(</span><span class="mi">0</span><span class="p" data-group-id="9190214226-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0664512766-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0664512766-6">[</span><span class="p" data-group-id="0664512766-6">]</span><span class="p" data-group-id="0664512766-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9190214226-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9190214226-6">[</span><span class="p" data-group-id="9190214226-6">]</span><span class="p" data-group-id="9190214226-5">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="0664512766-7">(</span><span class="n">N</span><span class="p" data-group-id="0664512766-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0664512766-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0664512766-9">(</span><span class="p" data-group-id="0664512766-9">)</span><span class="p" data-group-id="0664512766-8">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="9190214226-7">(</span><span class="n">N</span><span class="p" data-group-id="9190214226-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9190214226-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="9190214226-9">(</span><span class="p" data-group-id="9190214226-9">)</span><span class="p" data-group-id="9190214226-8">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0664512766-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0664512766-11">[</span><span class="p" data-group-id="0664512766-11">]</span><span class="p" data-group-id="0664512766-10">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9190214226-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9190214226-11">[</span><span class="p" data-group-id="9190214226-11">]</span><span class="p" data-group-id="9190214226-10">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="0664512766-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="0664512766-12">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="9190214226-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="9190214226-12">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="0664512766-13">(</span><span class="p" data-group-id="0664512766-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="9190214226-13">(</span><span class="p" data-group-id="9190214226-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0664512766-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0664512766-15">[</span><span class="p" data-group-id="0664512766-15">]</span><span class="p" data-group-id="0664512766-14">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0664512766-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="0664512766-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0664512766-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0664512766-18">[</span><span class="p" data-group-id="0664512766-18">]</span><span class="p" data-group-id="0664512766-17">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9190214226-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9190214226-15">[</span><span class="p" data-group-id="9190214226-15">]</span><span class="p" data-group-id="9190214226-14">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="9190214226-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="9190214226-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9190214226-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9190214226-18">[</span><span class="p" data-group-id="9190214226-18">]</span><span class="p" data-group-id="9190214226-17">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="0664512766-19">(</span><span class="p" data-group-id="0664512766-19">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="9190214226-19">(</span><span class="p" data-group-id="9190214226-19">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="0664512766-20">(</span><span class="p" data-group-id="0664512766-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="0664512766-21">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="0664512766-22">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0664512766-23">[</span><span class="p" data-group-id="0664512766-23">]</span><span class="p" data-group-id="0664512766-22">)</span><span class="p" data-group-id="0664512766-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="0664512766-24">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0664512766-25">[</span><span class="mi">3</span><span class="p" data-group-id="0664512766-25">]</span><span class="p" data-group-id="0664512766-24">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nf">c</span><span class="p" data-group-id="5343453556-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="5343453556-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5343453556-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut16</span><span class="p" data-group-id="5343453556-2">}</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">tut16</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5343453556-3">(</span><span class="p" data-group-id="5343453556-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="9190214226-20">(</span><span class="p" data-group-id="9190214226-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="9190214226-21">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="9190214226-22">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9190214226-23">[</span><span class="p" data-group-id="9190214226-23">]</span><span class="p" data-group-id="9190214226-22">)</span><span class="p" data-group-id="9190214226-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="9190214226-24">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9190214226-25">[</span><span class="mi">3</span><span class="p" data-group-id="9190214226-25">]</span><span class="p" data-group-id="9190214226-24">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nf">c</span><span class="p" data-group-id="5250214837-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="5250214837-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5250214837-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut16</span><span class="p" data-group-id="5250214837-2">}</span><span class="gp unselectable">
│ │ │ │ +3&gt; </span><span class="nc">tut16</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5250214837-3">(</span><span class="p" data-group-id="5250214837-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.38</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="ss">ping</span><span class="w"> </span><span class="ss">finished</span><span class="w">
│ │ │ │ -</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>Here the <code class="inline">start/0</code> function,</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="6064410923-1">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="6064410923-2">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6064410923-3">[</span><span class="p" data-group-id="6064410923-3">]</span><span class="p" data-group-id="6064410923-2">)</span><span class="p" data-group-id="6064410923-1">)</span><span class="p">,</span></code></pre><p>both spawns the &quot;pong&quot; process and gives it the name <code class="inline">pong</code>. In the &quot;ping&quot;
│ │ │ │ -process, messages can be sent to <code class="inline">pong</code> by:</p><pre><code class="makeup erlang" translate="no"><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7314801685-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7314801685-2">(</span><span class="p" data-group-id="7314801685-2">)</span><span class="p" data-group-id="7314801685-1">}</span><span class="p">,</span></code></pre><p><code class="inline">ping/2</code> now becomes <code class="inline">ping/1</code> as the argument <code class="inline">Pong_PID</code> is not needed.</p><h2 id="distributed-programming" class="section-heading">
│ │ │ │ +</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>Here the <code class="inline">start/0</code> function,</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="2247562347-1">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="2247562347-2">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2247562347-3">[</span><span class="p" data-group-id="2247562347-3">]</span><span class="p" data-group-id="2247562347-2">)</span><span class="p" data-group-id="2247562347-1">)</span><span class="p">,</span></code></pre><p>both spawns the &quot;pong&quot; process and gives it the name <code class="inline">pong</code>. In the &quot;ping&quot;
│ │ │ │ +process, messages can be sent to <code class="inline">pong</code> by:</p><pre><code class="makeup erlang" translate="no"><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7478181601-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7478181601-2">(</span><span class="p" data-group-id="7478181601-2">)</span><span class="p" data-group-id="7478181601-1">}</span><span class="p">,</span></code></pre><p><code class="inline">ping/2</code> now becomes <code class="inline">ping/1</code> as the argument <code class="inline">Pong_PID</code> is not needed.</p><h2 id="distributed-programming" class="section-heading">
│ │ │ │    <a href="#distributed-programming" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Distributed Programming</span>
│ │ │ │  </h2>
│ │ │ │  <p>Let us rewrite the ping pong program with &quot;ping&quot; and &quot;pong&quot; on different
│ │ │ │  computers. First a few things are needed to set up to get this to work. The
│ │ │ │ @@ -255,106 +255,106 @@
│ │ │ │  of the file. This is a requirement.</p><p>When you start an Erlang system that is going to talk to other Erlang systems,
│ │ │ │  you must give it a name, for example:</p><pre><code class="text">$ erl -sname my_name</code></pre><p>We will see more details of this later. If you want to experiment with
│ │ │ │  distributed Erlang, but you only have one computer to work on, you can start two
│ │ │ │  separate Erlang systems on the same computer but give them different names. Each
│ │ │ │  Erlang system running on a computer is called an <em>Erlang node</em>.</p><p>(Note: <code class="inline">erl -sname</code> assumes that all nodes are in the same IP domain and we can
│ │ │ │  use only the first component of the IP address, if we want to use nodes in
│ │ │ │  different domains we use <code class="inline">-name</code> instead, but then all IP address must be given
│ │ │ │ -in full.)</p><p>Here is the ping pong example modified to run on two separate nodes:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0204952469-1">(</span><span class="ss">tut17</span><span class="p" data-group-id="0204952469-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +in full.)</p><p>Here is the ping pong example modified to run on two separate nodes:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2525380200-1">(</span><span class="ss">tut17</span><span class="p" data-group-id="2525380200-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0204952469-2">(</span><span class="p" data-group-id="0204952469-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0204952469-3">]</span><span class="p" data-group-id="0204952469-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2525380200-2">(</span><span class="p" data-group-id="2525380200-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2525380200-3">]</span><span class="p" data-group-id="2525380200-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="0204952469-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0204952469-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0204952469-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0204952469-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0204952469-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0204952469-7">[</span><span class="p" data-group-id="0204952469-7">]</span><span class="p" data-group-id="0204952469-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="2525380200-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2525380200-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2525380200-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2525380200-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2525380200-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2525380200-7">[</span><span class="p" data-group-id="2525380200-7">]</span><span class="p" data-group-id="2525380200-6">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="0204952469-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0204952469-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0204952469-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0204952469-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0204952469-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0204952469-11">(</span><span class="p" data-group-id="0204952469-11">)</span><span class="p" data-group-id="0204952469-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="2525380200-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2525380200-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2525380200-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2525380200-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2525380200-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2525380200-11">(</span><span class="p" data-group-id="2525380200-11">)</span><span class="p" data-group-id="2525380200-10">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0204952469-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0204952469-13">[</span><span class="p" data-group-id="0204952469-13">]</span><span class="p" data-group-id="0204952469-12">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2525380200-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2525380200-13">[</span><span class="p" data-group-id="2525380200-13">]</span><span class="p" data-group-id="2525380200-12">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="0204952469-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0204952469-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="2525380200-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2525380200-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="0204952469-15">(</span><span class="p" data-group-id="0204952469-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="2525380200-15">(</span><span class="p" data-group-id="2525380200-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0204952469-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0204952469-17">[</span><span class="p" data-group-id="0204952469-17">]</span><span class="p" data-group-id="0204952469-16">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0204952469-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="0204952469-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0204952469-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0204952469-20">[</span><span class="p" data-group-id="0204952469-20">]</span><span class="p" data-group-id="0204952469-19">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2525380200-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2525380200-17">[</span><span class="p" data-group-id="2525380200-17">]</span><span class="p" data-group-id="2525380200-16">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="2525380200-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="2525380200-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2525380200-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2525380200-20">[</span><span class="p" data-group-id="2525380200-20">]</span><span class="p" data-group-id="2525380200-19">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="0204952469-21">(</span><span class="p" data-group-id="0204952469-21">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="2525380200-21">(</span><span class="p" data-group-id="2525380200-21">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_pong</span><span class="p" data-group-id="0204952469-22">(</span><span class="p" data-group-id="0204952469-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="0204952469-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="0204952469-24">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0204952469-25">[</span><span class="p" data-group-id="0204952469-25">]</span><span class="p" data-group-id="0204952469-24">)</span><span class="p" data-group-id="0204952469-23">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_pong</span><span class="p" data-group-id="2525380200-22">(</span><span class="p" data-group-id="2525380200-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="2525380200-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="2525380200-24">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2525380200-25">[</span><span class="p" data-group-id="2525380200-25">]</span><span class="p" data-group-id="2525380200-24">)</span><span class="p" data-group-id="2525380200-23">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start_ping</span><span class="p" data-group-id="0204952469-26">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="0204952469-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="0204952469-27">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0204952469-28">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0204952469-28">]</span><span class="p" data-group-id="0204952469-27">)</span><span class="p">.</span></code></pre><p>Let us assume there are two computers called gollum and kosken. First a node is
│ │ │ │ +</span><span class="nf">start_ping</span><span class="p" data-group-id="2525380200-26">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="2525380200-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="2525380200-27">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2525380200-28">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2525380200-28">]</span><span class="p" data-group-id="2525380200-27">)</span><span class="p">.</span></code></pre><p>Let us assume there are two computers called gollum and kosken. First a node is
│ │ │ │  started on kosken, called ping, and then a node on gollum, called pong.</p><p>On kosken (on a Linux/UNIX system):</p><pre><code class="text">kosken&gt; erl -sname ping
│ │ │ │  Erlang (BEAM) emulator version 5.2.3.7 [hipe] [threads:0]
│ │ │ │  
│ │ │ │  Eshell V5.2.3.7  (abort with ^G)
│ │ │ │  (ping@kosken)1&gt;</code></pre><p>On gollum:</p><pre><code class="text">gollum&gt; erl -sname pong
│ │ │ │  Erlang (BEAM) emulator version 5.2.3.7 [hipe] [threads:0]
│ │ │ │  
│ │ │ │  Eshell V5.2.3.7  (abort with ^G)
│ │ │ │ -(pong@gollum)1&gt;</code></pre><p>Now the &quot;pong&quot; process on gollum is started:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_pong</span><span class="p" data-group-id="9566057946-1">(</span><span class="p" data-group-id="9566057946-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +(pong@gollum)1&gt;</code></pre><p>Now the &quot;pong&quot; process on gollum is started:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_pong</span><span class="p" data-group-id="2791339121-1">(</span><span class="p" data-group-id="2791339121-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span></code></pre><p>And the &quot;ping&quot; process on kosken is started (from the code above you can see
│ │ │ │  that a parameter of the <code class="inline">start_ping</code> function is the node name of the Erlang
│ │ │ │ -system where &quot;pong&quot; is running):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(ping@kosken)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_ping</span><span class="p" data-group-id="7982277417-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="7982277417-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +system where &quot;pong&quot; is running):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(ping@kosken)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_ping</span><span class="p" data-group-id="0881220408-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="0881220408-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.37</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="ss">ping</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>As shown, the ping pong program has run. On the &quot;pong&quot; side:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)2&gt; </span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="nf">finished</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4282135023-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="4282135023-1">)</span><span class="mi">2</span><span class="o">&gt;</span><span class="w"> </span></code></pre><p>Looking at the <code class="inline">tut17</code> code, you see that the <code class="inline">pong</code> function itself is
│ │ │ │ +</span><span class="p" data-group-id="5843320088-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="5843320088-1">)</span><span class="mi">2</span><span class="o">&gt;</span><span class="w"> </span></code></pre><p>Looking at the <code class="inline">tut17</code> code, you see that the <code class="inline">pong</code> function itself is
│ │ │ │  unchanged, the following lines work in the same way irrespective of on which
│ │ │ │ -node the &quot;ping&quot; process is executes:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3224052320-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="3224052320-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3224052320-2">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3224052320-3">[</span><span class="p" data-group-id="3224052320-3">]</span><span class="p" data-group-id="3224052320-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +node the &quot;ping&quot; process is executes:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8905919435-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="8905919435-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8905919435-2">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8905919435-3">[</span><span class="p" data-group-id="8905919435-3">]</span><span class="p" data-group-id="8905919435-2">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span></code></pre><p>Thus, Erlang pids contain information about where the process executes. So if
│ │ │ │  you know the pid of a process, the <code class="inline">!</code> operator can be used to send it a
│ │ │ │ -message disregarding if the process is on the same node or on a different node.</p><p>A difference is how messages are sent to a registered process on another node:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2277554088-1">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2277554088-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2277554088-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2277554088-3">(</span><span class="p" data-group-id="2277554088-3">)</span><span class="p" data-group-id="2277554088-2">}</span><span class="p">,</span></code></pre><p>A tuple <code class="inline">{registered_name,node_name}</code> is used instead of just the
│ │ │ │ +message disregarding if the process is on the same node or on a different node.</p><p>A difference is how messages are sent to a registered process on another node:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7471166648-1">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="7471166648-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7471166648-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7471166648-3">(</span><span class="p" data-group-id="7471166648-3">)</span><span class="p" data-group-id="7471166648-2">}</span><span class="p">,</span></code></pre><p>A tuple <code class="inline">{registered_name,node_name}</code> is used instead of just the
│ │ │ │  <code class="inline">registered_name</code>.</p><p>In the previous example, &quot;ping&quot; and &quot;pong&quot; were started from the shells of two
│ │ │ │  separate Erlang nodes. <code class="inline">spawn</code> can also be used to start processes in other
│ │ │ │  nodes.</p><p>The next example is the ping pong program, yet again, but this time &quot;ping&quot; is
│ │ │ │ -started in another node:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0114398055-1">(</span><span class="ss">tut18</span><span class="p" data-group-id="0114398055-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +started in another node:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1331168071-1">(</span><span class="ss">tut18</span><span class="p" data-group-id="1331168071-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0114398055-2">(</span><span class="p" data-group-id="0114398055-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0114398055-3">]</span><span class="p" data-group-id="0114398055-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1331168071-2">(</span><span class="p" data-group-id="1331168071-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1331168071-3">]</span><span class="p" data-group-id="1331168071-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="0114398055-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0114398055-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0114398055-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0114398055-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0114398055-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0114398055-7">[</span><span class="p" data-group-id="0114398055-7">]</span><span class="p" data-group-id="0114398055-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="1331168071-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1331168071-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1331168071-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1331168071-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1331168071-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1331168071-7">[</span><span class="p" data-group-id="1331168071-7">]</span><span class="p" data-group-id="1331168071-6">)</span><span class="p">;</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="0114398055-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0114398055-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0114398055-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0114398055-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0114398055-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0114398055-11">(</span><span class="p" data-group-id="0114398055-11">)</span><span class="p" data-group-id="0114398055-10">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="1331168071-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1331168071-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1331168071-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1331168071-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1331168071-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1331168071-11">(</span><span class="p" data-group-id="1331168071-11">)</span><span class="p" data-group-id="1331168071-10">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0114398055-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0114398055-13">[</span><span class="p" data-group-id="0114398055-13">]</span><span class="p" data-group-id="0114398055-12">)</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1331168071-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1331168071-13">[</span><span class="p" data-group-id="1331168071-13">]</span><span class="p" data-group-id="1331168071-12">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="0114398055-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0114398055-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="1331168071-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1331168071-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="0114398055-15">(</span><span class="p" data-group-id="0114398055-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="1331168071-15">(</span><span class="p" data-group-id="1331168071-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0114398055-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0114398055-17">[</span><span class="p" data-group-id="0114398055-17">]</span><span class="p" data-group-id="0114398055-16">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0114398055-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="0114398055-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0114398055-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0114398055-20">[</span><span class="p" data-group-id="0114398055-20">]</span><span class="p" data-group-id="0114398055-19">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1331168071-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1331168071-17">[</span><span class="p" data-group-id="1331168071-17">]</span><span class="p" data-group-id="1331168071-16">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="1331168071-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="1331168071-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1331168071-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1331168071-20">[</span><span class="p" data-group-id="1331168071-20">]</span><span class="p" data-group-id="1331168071-19">)</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="0114398055-21">(</span><span class="p" data-group-id="0114398055-21">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="1331168071-21">(</span><span class="p" data-group-id="1331168071-21">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="0114398055-22">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="0114398055-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="0114398055-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="0114398055-24">(</span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0114398055-25">[</span><span class="p" data-group-id="0114398055-25">]</span><span class="p" data-group-id="0114398055-24">)</span><span class="p" data-group-id="0114398055-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="0114398055-26">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0114398055-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="0114398055-28">(</span><span class="p" data-group-id="0114398055-28">)</span><span class="p" data-group-id="0114398055-27">]</span><span class="p" data-group-id="0114398055-26">)</span><span class="p">.</span></code></pre><p>Assuming an Erlang system called ping (but not the &quot;ping&quot; process) has already
│ │ │ │ -been started on kosken, then on gollum this is done:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut18</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4287791559-1">(</span><span class="ss">ping@kosken</span><span class="p" data-group-id="4287791559-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1331168071-22">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="1331168071-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="1331168071-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1331168071-24">(</span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1331168071-25">[</span><span class="p" data-group-id="1331168071-25">]</span><span class="p" data-group-id="1331168071-24">)</span><span class="p" data-group-id="1331168071-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1331168071-26">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1331168071-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="1331168071-28">(</span><span class="p" data-group-id="1331168071-28">)</span><span class="p" data-group-id="1331168071-27">]</span><span class="p" data-group-id="1331168071-26">)</span><span class="p">.</span></code></pre><p>Assuming an Erlang system called ping (but not the &quot;ping&quot; process) has already
│ │ │ │ +been started on kosken, then on gollum this is done:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut18</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="0716470308-1">(</span><span class="ss">ping@kosken</span><span class="p" data-group-id="0716470308-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">3934.39</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ │ @@ -421,184 +421,184 @@
│ │ │ │  </span><span class="c1">%%% Started: messenger:client(Server_Node, Name)</span><span class="w">
│ │ │ │  </span><span class="c1">%%% To client: logoff</span><span class="w">
│ │ │ │  </span><span class="c1">%%% To client: {message_to, ToName, Message}</span><span class="w">
│ │ │ │  </span><span class="c1">%%%</span><span class="w">
│ │ │ │  </span><span class="c1">%%% Configuration: change the server_node() function to return the</span><span class="w">
│ │ │ │  </span><span class="c1">%%% name of the node where the messenger server runs</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4138002751-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="4138002751-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4138002751-2">(</span><span class="p" data-group-id="4138002751-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="4138002751-3">]</span><span class="p" data-group-id="4138002751-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0950658908-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="0950658908-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0950658908-2">(</span><span class="p" data-group-id="0950658908-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0950658908-3">]</span><span class="p" data-group-id="0950658908-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Change the function below to return the name of the node where the</span><span class="w">
│ │ │ │  </span><span class="c1">%%% messenger server runs</span><span class="w">
│ │ │ │ -</span><span class="nf">server_node</span><span class="p" data-group-id="4138002751-4">(</span><span class="p" data-group-id="4138002751-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_node</span><span class="p" data-group-id="0950658908-4">(</span><span class="p" data-group-id="0950658908-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">messenger@super</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% This is the server process for the &quot;messenger&quot;</span><span class="w">
│ │ │ │  </span><span class="c1">%%% the user list has the format [{ClientPid1, Name1},{ClientPid22, Name2},...]</span><span class="w">
│ │ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="4138002751-5">(</span><span class="n">User_List</span><span class="p" data-group-id="4138002751-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="0950658908-5">(</span><span class="n">User_List</span><span class="p" data-group-id="0950658908-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-6">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4138002751-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="4138002751-7">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="4138002751-8">(</span><span class="n">New_User_List</span><span class="p" data-group-id="4138002751-8">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-9">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="4138002751-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="4138002751-10">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="4138002751-11">(</span><span class="n">New_User_List</span><span class="p" data-group-id="4138002751-11">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-12">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="4138002751-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4138002751-14">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-15">[</span><span class="n">User_List</span><span class="p" data-group-id="4138002751-15">]</span><span class="p" data-group-id="4138002751-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="4138002751-16">(</span><span class="n">User_List</span><span class="p" data-group-id="4138002751-16">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-6">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0950658908-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="0950658908-7">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-7">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="0950658908-8">(</span><span class="n">New_User_List</span><span class="p" data-group-id="0950658908-8">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-9">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="0950658908-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="0950658908-10">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="0950658908-11">(</span><span class="n">New_User_List</span><span class="p" data-group-id="0950658908-11">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-12">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="0950658908-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-13">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0950658908-14">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-15">[</span><span class="n">User_List</span><span class="p" data-group-id="0950658908-15">]</span><span class="p" data-group-id="0950658908-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="0950658908-16">(</span><span class="n">User_List</span><span class="p" data-group-id="0950658908-16">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Start the server</span><span class="w">
│ │ │ │ -</span><span class="nf">start_server</span><span class="p" data-group-id="4138002751-17">(</span><span class="p" data-group-id="4138002751-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="4138002751-18">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="4138002751-19">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-20">[</span><span class="p" data-group-id="4138002751-21">[</span><span class="p" data-group-id="4138002751-21">]</span><span class="p" data-group-id="4138002751-20">]</span><span class="p" data-group-id="4138002751-19">)</span><span class="p" data-group-id="4138002751-18">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start_server</span><span class="p" data-group-id="0950658908-17">(</span><span class="p" data-group-id="0950658908-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="0950658908-18">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="0950658908-19">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-20">[</span><span class="p" data-group-id="0950658908-21">[</span><span class="p" data-group-id="0950658908-21">]</span><span class="p" data-group-id="0950658908-20">]</span><span class="p" data-group-id="0950658908-19">)</span><span class="p" data-group-id="0950658908-18">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server adds a new user to the user list</span><span class="w">
│ │ │ │ -</span><span class="nf">server_logon</span><span class="p" data-group-id="4138002751-22">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_logon</span><span class="p" data-group-id="0950658908-22">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% check if logged on anywhere else</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="4138002751-23">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-23">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="0950658908-23">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-23">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-24">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="4138002751-24">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-24">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="0950658908-24">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │ │              </span><span class="n">User_List</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-25">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="4138002751-25">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="4138002751-26">[</span><span class="p" data-group-id="4138002751-27">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4138002751-27">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-26">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-25">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="0950658908-25">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="0950658908-26">[</span><span class="p" data-group-id="0950658908-27">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0950658908-27">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-26">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server deletes a user from the user list</span><span class="w">
│ │ │ │ -</span><span class="nf">server_logoff</span><span class="p" data-group-id="4138002751-28">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="4138002751-29">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-29">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">server_logoff</span><span class="p" data-group-id="0950658908-28">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="0950658908-29">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-29">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% Server transfers a message between user</span><span class="w">
│ │ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="4138002751-30">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="0950658908-30">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% check that the user is logged on and who he is</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="4138002751-31">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-31">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="0950658908-31">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-31">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-32">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="4138002751-32">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-33">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-34">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4138002751-34">}</span><span class="p" data-group-id="4138002751-33">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="4138002751-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-35">)</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-32">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="0950658908-32">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-33">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-34">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0950658908-34">}</span><span class="p" data-group-id="0950658908-33">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="0950658908-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-35">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="c1">%%% If the user exists, send the message</span><span class="w">
│ │ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="4138002751-36">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="0950658908-36">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="c1">%% Find the receiver and send the message</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="4138002751-37">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="4138002751-37">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="0950658908-37">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0950658908-37">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-38">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="4138002751-38">}</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-39">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-40">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="4138002751-40">}</span><span class="p" data-group-id="4138002751-39">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-41">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-41">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="4138002751-42">}</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-38">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="0950658908-38">}</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-39">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-40">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="0950658908-40">}</span><span class="p" data-group-id="0950658908-39">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-41">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-41">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="0950658908-42">}</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% User Commands</span><span class="w">
│ │ │ │ -</span><span class="nf">logon</span><span class="p" data-group-id="4138002751-43">(</span><span class="n">Name</span><span class="p" data-group-id="4138002751-43">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="4138002751-44">(</span><span class="ss">mess_client</span><span class="p" data-group-id="4138002751-44">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">logon</span><span class="p" data-group-id="0950658908-43">(</span><span class="n">Name</span><span class="p" data-group-id="0950658908-43">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="0950658908-44">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0950658908-44">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nf">register</span><span class="p" data-group-id="4138002751-45">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ │ -                     </span><span class="nf">spawn</span><span class="p" data-group-id="4138002751-46">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-47">[</span><span class="nf">server_node</span><span class="p" data-group-id="4138002751-48">(</span><span class="p" data-group-id="4138002751-48">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4138002751-47">]</span><span class="p" data-group-id="4138002751-46">)</span><span class="p" data-group-id="4138002751-45">)</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="nf">register</span><span class="p" data-group-id="0950658908-45">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ │ +                     </span><span class="nf">spawn</span><span class="p" data-group-id="0950658908-46">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-47">[</span><span class="nf">server_node</span><span class="p" data-group-id="0950658908-48">(</span><span class="p" data-group-id="0950658908-48">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0950658908-47">]</span><span class="p" data-group-id="0950658908-46">)</span><span class="p" data-group-id="0950658908-45">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">already_logged_on</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">logoff</span><span class="p" data-group-id="4138002751-49">(</span><span class="p" data-group-id="4138002751-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">logoff</span><span class="p" data-group-id="0950658908-49">(</span><span class="p" data-group-id="0950658908-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">logoff</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">message</span><span class="p" data-group-id="4138002751-50">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="4138002751-51">(</span><span class="ss">mess_client</span><span class="p" data-group-id="4138002751-51">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ │ +</span><span class="nf">message</span><span class="p" data-group-id="0950658908-50">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="0950658908-51">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0950658908-51">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">not_logged_on</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-52">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-52">}</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-52">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-52">}</span><span class="p">,</span><span class="w">
│ │ │ │               </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% The client process which runs on each server node</span><span class="w">
│ │ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="4138002751-53">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4138002751-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4138002751-54">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="4138002751-54">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-55">{</span><span class="nf">self</span><span class="p" data-group-id="4138002751-56">(</span><span class="p" data-group-id="4138002751-56">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4138002751-55">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">await_result</span><span class="p" data-group-id="4138002751-57">(</span><span class="p" data-group-id="4138002751-57">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="4138002751-58">(</span><span class="n">Server_Node</span><span class="p" data-group-id="4138002751-58">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="0950658908-53">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0950658908-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0950658908-54">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0950658908-54">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-55">{</span><span class="nf">self</span><span class="p" data-group-id="0950658908-56">(</span><span class="p" data-group-id="0950658908-56">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0950658908-55">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">await_result</span><span class="p" data-group-id="0950658908-57">(</span><span class="p" data-group-id="0950658908-57">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="0950658908-58">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0950658908-58">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="4138002751-59">(</span><span class="n">Server_Node</span><span class="p" data-group-id="4138002751-59">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="0950658908-59">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0950658908-59">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">logoff</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="4138002751-60">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="4138002751-60">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-61">{</span><span class="nf">self</span><span class="p" data-group-id="4138002751-62">(</span><span class="p" data-group-id="4138002751-62">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="4138002751-61">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="4138002751-63">(</span><span class="ss">normal</span><span class="p" data-group-id="4138002751-63">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-64">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-64">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="p" data-group-id="4138002751-65">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="4138002751-65">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4138002751-66">{</span><span class="nf">self</span><span class="p" data-group-id="4138002751-67">(</span><span class="p" data-group-id="4138002751-67">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-66">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">await_result</span><span class="p" data-group-id="4138002751-68">(</span><span class="p" data-group-id="4138002751-68">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-69">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-69">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4138002751-70">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-71">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4138002751-71">]</span><span class="p" data-group-id="4138002751-70">)</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="0950658908-60">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0950658908-60">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-61">{</span><span class="nf">self</span><span class="p" data-group-id="0950658908-62">(</span><span class="p" data-group-id="0950658908-62">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="0950658908-61">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0950658908-63">(</span><span class="ss">normal</span><span class="p" data-group-id="0950658908-63">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-64">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-64">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="p" data-group-id="0950658908-65">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0950658908-65">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0950658908-66">{</span><span class="nf">self</span><span class="p" data-group-id="0950658908-67">(</span><span class="p" data-group-id="0950658908-67">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-66">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">await_result</span><span class="p" data-group-id="0950658908-68">(</span><span class="p" data-group-id="0950658908-68">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-69">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-69">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0950658908-70">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-71">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0950658908-71">]</span><span class="p" data-group-id="0950658908-70">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="4138002751-72">(</span><span class="n">Server_Node</span><span class="p" data-group-id="4138002751-72">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="0950658908-72">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0950658908-72">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="c1">%%% wait for a response from the server</span><span class="w">
│ │ │ │ -</span><span class="nf">await_result</span><span class="p" data-group-id="4138002751-73">(</span><span class="p" data-group-id="4138002751-73">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">await_result</span><span class="p" data-group-id="0950658908-73">(</span><span class="p" data-group-id="0950658908-73">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-74">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="4138002751-74">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4138002751-75">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-76">[</span><span class="n">Why</span><span class="p" data-group-id="4138002751-76">]</span><span class="p" data-group-id="4138002751-75">)</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="4138002751-77">(</span><span class="ss">normal</span><span class="p" data-group-id="4138002751-77">)</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4138002751-78">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="4138002751-78">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4138002751-79">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4138002751-80">[</span><span class="n">What</span><span class="p" data-group-id="4138002751-80">]</span><span class="p" data-group-id="4138002751-79">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-74">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="0950658908-74">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0950658908-75">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-76">[</span><span class="n">Why</span><span class="p" data-group-id="0950658908-76">]</span><span class="p" data-group-id="0950658908-75">)</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0950658908-77">(</span><span class="ss">normal</span><span class="p" data-group-id="0950658908-77">)</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0950658908-78">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="0950658908-78">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0950658908-79">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0950658908-80">[</span><span class="n">What</span><span class="p" data-group-id="0950658908-80">]</span><span class="p" data-group-id="0950658908-79">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>To use this program, you need to:</p><ul><li>Configure the <code class="inline">server_node()</code> function.</li><li>Copy the compiled code (<code class="inline">messenger.beam</code>) to the directory on each computer
│ │ │ │  where you start Erlang.</li></ul><p>In the following example using this program, nodes are started on four different
│ │ │ │  computers. If you do not have that many machines available on your network, you
│ │ │ │  can start several nodes on the same machine.</p><p>Four Erlang nodes are started up: messenger@super, c1@bilbo, c2@kosken,
│ │ │ │ -c3@gollum.</p><p>First the server at messenger@super is started up:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(messenger@super)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">start_server</span><span class="p" data-group-id="3468982900-1">(</span><span class="p" data-group-id="3468982900-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="ss">true</span></code></pre><p>Now Peter logs on at c1@bilbo:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="7799290292-1">(</span><span class="ss">peter</span><span class="p" data-group-id="7799290292-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +c3@gollum.</p><p>First the server at messenger@super is started up:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(messenger@super)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">start_server</span><span class="p" data-group-id="3236576973-1">(</span><span class="p" data-group-id="3236576973-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="ss">true</span></code></pre><p>Now Peter logs on at c1@bilbo:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="8302988150-1">(</span><span class="ss">peter</span><span class="p" data-group-id="8302988150-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="w">
│ │ │ │ -</span><span class="ss">logged_on</span></code></pre><p>James logs on at c2@kosken:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="3850258142-1">(</span><span class="ss">james</span><span class="p" data-group-id="3850258142-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="ss">logged_on</span></code></pre><p>James logs on at c2@kosken:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="8692755590-1">(</span><span class="ss">james</span><span class="p" data-group-id="8692755590-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="w">
│ │ │ │ -</span><span class="ss">logged_on</span></code></pre><p>And Fred logs on at c3@gollum:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c3@gollum)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="8697029934-1">(</span><span class="ss">fred</span><span class="p" data-group-id="8697029934-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="ss">logged_on</span></code></pre><p>And Fred logs on at c3@gollum:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c3@gollum)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="2111451612-1">(</span><span class="ss">fred</span><span class="p" data-group-id="2111451612-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="w">
│ │ │ │ -</span><span class="ss">logged_on</span></code></pre><p>Now Peter sends Fred a message:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="0973897544-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0973897544-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="ss">logged_on</span></code></pre><p>Now Peter sends Fred a message:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="7059944318-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="7059944318-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="ss">sent</span></code></pre><p>Fred receives the message and sends a message to Peter and logs off:</p><pre><code class="makeup erlang" translate="no"><span class="n">Message</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="nc">peter</span><span class="p">:</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ │ -(c3@gollum)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="4626084803-1">(</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;go away, I&#39;m busy&quot;</span><span class="p" data-group-id="4626084803-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +(c3@gollum)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="6042438434-1">(</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;go away, I&#39;m busy&quot;</span><span class="p" data-group-id="6042438434-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="nf">sent</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4626084803-2">(</span><span class="ss">c3@gollum</span><span class="p" data-group-id="4626084803-2">)</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logoff</span><span class="p" data-group-id="4626084803-3">(</span><span class="p" data-group-id="4626084803-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="ss">logoff</span></code></pre><p>James now tries to send a message to Fred:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="9839468835-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;peter doesn&#39;t like you&quot;</span><span class="p" data-group-id="9839468835-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6042438434-2">(</span><span class="ss">c3@gollum</span><span class="p" data-group-id="6042438434-2">)</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logoff</span><span class="p" data-group-id="6042438434-3">(</span><span class="p" data-group-id="6042438434-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="ss">logoff</span></code></pre><p>James now tries to send a message to Fred:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="1682930756-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;peter doesn&#39;t like you&quot;</span><span class="p" data-group-id="1682930756-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ │  </span><span class="ss">receiver_not_found</span></code></pre><p>But this fails as Fred has already logged off.</p><p>First let us look at some of the new concepts that have been introduced.</p><p>There are two versions of the <code class="inline">server_transfer</code> function: one with four
│ │ │ │  arguments (<code class="inline">server_transfer/4</code>) and one with five (<code class="inline">server_transfer/5</code>). These
│ │ │ │  are regarded by Erlang as two separate functions.</p><p>Notice how to write the <code class="inline">server</code> function so that it calls itself, through
│ │ │ │  <code class="inline">server(User_List)</code>, and thus creates a loop. The Erlang compiler is &quot;clever&quot;
│ │ │ │  and optimizes the code so that this really is a sort of loop and not a proper
│ │ │ │  function call. But this only works if there is no code after the call.
│ │ │ │  Otherwise, the compiler expects the call to return and make a proper function
│ │ │ │  call. This would result in the process getting bigger and bigger for every loop.</p><p>Functions in the <code class="inline">lists</code> module are used. This is a very useful module and a
│ │ │ │  study of the manual page is recommended (<code class="inline">erl -man lists</code>).
│ │ │ │  <code class="inline">lists:keymember(Key,Position,Lists)</code> looks through a list of tuples and looks
│ │ │ │  at <code class="inline">Position</code> in each tuple to see if it is the same as <code class="inline">Key</code>. The first element
│ │ │ │  is position 1. If it finds a tuple where the element at <code class="inline">Position</code> is the same
│ │ │ │ -as <code class="inline">Key</code>, it returns <code class="inline">true</code>, otherwise <code class="inline">false</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="0656100779-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0656100779-2">[</span><span class="p" data-group-id="0656100779-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="0656100779-3">}</span><span class="p">,</span><span class="p" data-group-id="0656100779-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0656100779-4">}</span><span class="p">,</span><span class="p" data-group-id="0656100779-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0656100779-5">}</span><span class="p">,</span><span class="p" data-group-id="0656100779-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="0656100779-6">}</span><span class="p" data-group-id="0656100779-2">]</span><span class="p" data-group-id="0656100779-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +as <code class="inline">Key</code>, it returns <code class="inline">true</code>, otherwise <code class="inline">false</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="0864839451-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0864839451-2">[</span><span class="p" data-group-id="0864839451-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="0864839451-3">}</span><span class="p">,</span><span class="p" data-group-id="0864839451-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0864839451-4">}</span><span class="p">,</span><span class="p" data-group-id="0864839451-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0864839451-5">}</span><span class="p">,</span><span class="p" data-group-id="0864839451-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="0864839451-6">}</span><span class="p" data-group-id="0864839451-2">]</span><span class="p" data-group-id="0864839451-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="0656100779-7">(</span><span class="ss">p</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0656100779-8">[</span><span class="p" data-group-id="0656100779-9">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="0656100779-9">}</span><span class="p">,</span><span class="p" data-group-id="0656100779-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0656100779-10">}</span><span class="p">,</span><span class="p" data-group-id="0656100779-11">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0656100779-11">}</span><span class="p">,</span><span class="p" data-group-id="0656100779-12">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="0656100779-12">}</span><span class="p" data-group-id="0656100779-8">]</span><span class="p" data-group-id="0656100779-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="0864839451-7">(</span><span class="ss">p</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0864839451-8">[</span><span class="p" data-group-id="0864839451-9">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="0864839451-9">}</span><span class="p">,</span><span class="p" data-group-id="0864839451-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0864839451-10">}</span><span class="p">,</span><span class="p" data-group-id="0864839451-11">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="0864839451-11">}</span><span class="p">,</span><span class="p" data-group-id="0864839451-12">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="0864839451-12">}</span><span class="p" data-group-id="0864839451-8">]</span><span class="p" data-group-id="0864839451-7">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">false</span></code></pre><p><code class="inline">lists:keydelete</code> works in the same way but deletes the first tuple found (if
│ │ │ │ -any) and returns the remaining list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="6215437563-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6215437563-2">[</span><span class="p" data-group-id="6215437563-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="6215437563-3">}</span><span class="p">,</span><span class="p" data-group-id="6215437563-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6215437563-4">}</span><span class="p">,</span><span class="p" data-group-id="6215437563-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6215437563-5">}</span><span class="p">,</span><span class="p" data-group-id="6215437563-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="6215437563-6">}</span><span class="p" data-group-id="6215437563-2">]</span><span class="p" data-group-id="6215437563-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6215437563-7">[</span><span class="p" data-group-id="6215437563-8">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="6215437563-8">}</span><span class="p">,</span><span class="p" data-group-id="6215437563-9">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6215437563-9">}</span><span class="p">,</span><span class="p" data-group-id="6215437563-10">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="6215437563-10">}</span><span class="p" data-group-id="6215437563-7">]</span></code></pre><p><code class="inline">lists:keysearch</code> is like <code class="inline">lists:keymember</code>, but it returns
│ │ │ │ +any) and returns the remaining list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="1220945425-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1220945425-2">[</span><span class="p" data-group-id="1220945425-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="1220945425-3">}</span><span class="p">,</span><span class="p" data-group-id="1220945425-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1220945425-4">}</span><span class="p">,</span><span class="p" data-group-id="1220945425-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1220945425-5">}</span><span class="p">,</span><span class="p" data-group-id="1220945425-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="1220945425-6">}</span><span class="p" data-group-id="1220945425-2">]</span><span class="p" data-group-id="1220945425-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1220945425-7">[</span><span class="p" data-group-id="1220945425-8">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="1220945425-8">}</span><span class="p">,</span><span class="p" data-group-id="1220945425-9">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1220945425-9">}</span><span class="p">,</span><span class="p" data-group-id="1220945425-10">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="1220945425-10">}</span><span class="p" data-group-id="1220945425-7">]</span></code></pre><p><code class="inline">lists:keysearch</code> is like <code class="inline">lists:keymember</code>, but it returns
│ │ │ │  <code class="inline">{value,Tuple_Found}</code> or the atom <code class="inline">false</code>.</p><p>There are many very useful functions in the <code class="inline">lists</code> module.</p><p>An Erlang process (conceptually) runs until it does a <code class="inline">receive</code> and there is no
│ │ │ │  message which it wants to receive in the message queue. &quot;conceptually&quot; is used
│ │ │ │  here because the Erlang system shares the CPU time between the active processes
│ │ │ │  in the system.</p><p>A process terminates when there is nothing more for it to do, that is, the last
│ │ │ │  function it calls simply returns and does not call another function. Another way
│ │ │ │  for a process to terminate is for it to call <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit/1</code></a>. The argument
│ │ │ │  to <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit/1</code></a> has a special meaning, which is discussed later. In this
│ │ │ │  example, <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit(normal)</code></a> is done, which has the same effect as a
│ │ │ │  process running out of functions to call.</p><p>The BIF <a href="../../../lib/../erts/doc/html/erlang.html#whereis/1"><code class="inline">whereis(RegisteredName)</code></a> checks if a registered process
│ │ │ │  of name <code class="inline">RegisteredName</code> exists. If it exists, the pid of that process is
│ │ │ │  returned. If it does not exist, the atom <code class="inline">undefined</code> is returned.</p><p>You should by now be able to understand most of the code in the
│ │ │ │  messenger-module. Let us study one case in detail: a message is sent from one
│ │ │ │ -user to another.</p><p>The first user &quot;sends&quot; the message in the example above by:</p><pre><code class="makeup erlang" translate="no"><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="9431515037-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="9431515037-1">)</span></code></pre><p>After testing that the client process exists:</p><pre><code class="makeup erlang" translate="no"><span class="nf">whereis</span><span class="p" data-group-id="6832727222-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="6832727222-1">)</span></code></pre><p>And a message is sent to <code class="inline">mess_client</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1426214450-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1426214450-1">}</span></code></pre><p>The client sends the message to the server by:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0501547070-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="0501547070-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0501547070-2">{</span><span class="nf">self</span><span class="p" data-group-id="0501547070-3">(</span><span class="p" data-group-id="0501547070-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0501547070-2">}</span><span class="p">,</span></code></pre><p>And waits for a reply from the server.</p><p>The server receives this message and calls:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="3500268190-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="3500268190-1">)</span><span class="p">,</span></code></pre><p>This checks that the pid <code class="inline">From</code> is in the <code class="inline">User_List</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="2930187510-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="2930187510-1">)</span></code></pre><p>If <code class="inline">keysearch</code> returns the atom <code class="inline">false</code>, some error has occurred and the server
│ │ │ │ -sends back the message:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7370928697-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="7370928697-1">}</span></code></pre><p>This is received by the client, which in turn does <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit(normal)</code></a>
│ │ │ │ +user to another.</p><p>The first user &quot;sends&quot; the message in the example above by:</p><pre><code class="makeup erlang" translate="no"><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="2167011525-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="2167011525-1">)</span></code></pre><p>After testing that the client process exists:</p><pre><code class="makeup erlang" translate="no"><span class="nf">whereis</span><span class="p" data-group-id="4569911005-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="4569911005-1">)</span></code></pre><p>And a message is sent to <code class="inline">mess_client</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5837483191-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="5837483191-1">}</span></code></pre><p>The client sends the message to the server by:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2477511615-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="2477511615-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2477511615-2">{</span><span class="nf">self</span><span class="p" data-group-id="2477511615-3">(</span><span class="p" data-group-id="2477511615-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="2477511615-2">}</span><span class="p">,</span></code></pre><p>And waits for a reply from the server.</p><p>The server receives this message and calls:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="0161817158-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0161817158-1">)</span><span class="p">,</span></code></pre><p>This checks that the pid <code class="inline">From</code> is in the <code class="inline">User_List</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8420388726-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8420388726-1">)</span></code></pre><p>If <code class="inline">keysearch</code> returns the atom <code class="inline">false</code>, some error has occurred and the server
│ │ │ │ +sends back the message:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8851648169-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="8851648169-1">}</span></code></pre><p>This is received by the client, which in turn does <a href="../../../lib/../erts/doc/html/erlang.html#exit/1"><code class="inline">exit(normal)</code></a>
│ │ │ │  and terminates. If <code class="inline">keysearch</code> returns <code class="inline">{value,{From,Name}}</code> it is certain that
│ │ │ │ -the user is logged on and that his name (peter) is in variable <code class="inline">Name</code>.</p><p>Let us now call:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="8555163418-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8555163418-1">)</span></code></pre><p>Notice that as this is <code class="inline">server_transfer/5</code>, it is not the same as the previous
│ │ │ │ +the user is logged on and that his name (peter) is in variable <code class="inline">Name</code>.</p><p>Let us now call:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="5233964604-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5233964604-1">)</span></code></pre><p>Notice that as this is <code class="inline">server_transfer/5</code>, it is not the same as the previous
│ │ │ │  function <code class="inline">server_transfer/4</code>. Another <code class="inline">keysearch</code> is done on <code class="inline">User_List</code> to find
│ │ │ │ -the pid of the client corresponding to fred:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8437893559-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8437893559-1">)</span></code></pre><p>This time argument 2 is used, which is the second element in the tuple. If this
│ │ │ │ +the pid of the client corresponding to fred:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="2958837882-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="2958837882-1">)</span></code></pre><p>This time argument 2 is used, which is the second element in the tuple. If this
│ │ │ │  returns the atom <code class="inline">false</code>, fred is not logged on and the following message is
│ │ │ │ -sent:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8191821594-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="8191821594-1">}</span><span class="p">;</span></code></pre><p>This is received by the client.</p><p>If <code class="inline">keysearch</code> returns:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5930261472-1">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5930261472-2">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p" data-group-id="5930261472-2">}</span><span class="p" data-group-id="5930261472-1">}</span></code></pre><p>The following message is sent to fred's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1926368926-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1926368926-1">}</span><span class="p">,</span></code></pre><p>The following message is sent to peter's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6254014362-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="6254014362-1">}</span></code></pre><p>Fred's client receives the message and prints it:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6094624594-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6094624594-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6094624594-2">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6094624594-3">[</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6094624594-3">]</span><span class="p" data-group-id="6094624594-2">)</span></code></pre><p>Peter's client receives the message in the <code class="inline">await_result</code> function.</p>
│ │ │ │ +sent:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2193494780-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="2193494780-1">}</span><span class="p">;</span></code></pre><p>This is received by the client.</p><p>If <code class="inline">keysearch</code> returns:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2658176853-1">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2658176853-2">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p" data-group-id="2658176853-2">}</span><span class="p" data-group-id="2658176853-1">}</span></code></pre><p>The following message is sent to fred's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0132200295-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0132200295-1">}</span><span class="p">,</span></code></pre><p>The following message is sent to peter's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0299819675-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="0299819675-1">}</span></code></pre><p>Fred's client receives the message and prints it:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6640064303-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6640064303-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6640064303-2">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6640064303-3">[</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6640064303-3">]</span><span class="p" data-group-id="6640064303-2">)</span></code></pre><p>Peter's client receives the message in the <code class="inline">await_result</code> function.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/commoncaveats.xhtml
│ │ │ │ @@ -23,31 +23,31 @@
│ │ │ │  <p>This section lists a few constructs to watch out for.</p><h2 id="operator" class="section-heading">
│ │ │ │    <a href="#operator" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Operator <code class="inline">++</code></span>
│ │ │ │  </h2>
│ │ │ │  <p>The <code class="inline">++</code> operator copies its left-hand side operand. That is clearly
│ │ │ │ -seen if we do our own implementation in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_plus_plus</span><span class="p" data-group-id="9482864061-1">(</span><span class="p" data-group-id="9482864061-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9482864061-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9482864061-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9482864061-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="9482864061-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9482864061-4">)</span><span class="p" data-group-id="9482864061-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="9482864061-5">(</span><span class="p" data-group-id="9482864061-6">[</span><span class="p" data-group-id="9482864061-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="9482864061-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Tail</span><span class="p">.</span></code></pre><p>We must be careful how we use <code class="inline">++</code> in a loop. First is how not to use it:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_reverse</span><span class="p" data-group-id="2865582676-1">(</span><span class="p" data-group-id="2865582676-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2865582676-2">]</span><span class="p" data-group-id="2865582676-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">naive_reverse</span><span class="p" data-group-id="2865582676-3">(</span><span class="n">T</span><span class="p" data-group-id="2865582676-3">)</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="2865582676-4">[</span><span class="n">H</span><span class="p" data-group-id="2865582676-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">naive_reverse</span><span class="p" data-group-id="2865582676-5">(</span><span class="p" data-group-id="2865582676-6">[</span><span class="p" data-group-id="2865582676-6">]</span><span class="p" data-group-id="2865582676-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2865582676-7">[</span><span class="p" data-group-id="2865582676-7">]</span><span class="p">.</span></code></pre><p>As the <code class="inline">++</code> operator copies its left-hand side operand, the growing
│ │ │ │ -result is copied repeatedly, leading to quadratic complexity.</p><p>On the other hand, using <code class="inline">++</code> in loop like this is perfectly fine:</p><p><strong>OK</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="2959584156-1">(</span><span class="n">List</span><span class="p" data-group-id="2959584156-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="2959584156-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2959584156-3">[</span><span class="p" data-group-id="2959584156-3">]</span><span class="p" data-group-id="2959584156-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +seen if we do our own implementation in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_plus_plus</span><span class="p" data-group-id="3361102125-1">(</span><span class="p" data-group-id="3361102125-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3361102125-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="3361102125-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3361102125-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="3361102125-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="3361102125-4">)</span><span class="p" data-group-id="3361102125-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="3361102125-5">(</span><span class="p" data-group-id="3361102125-6">[</span><span class="p" data-group-id="3361102125-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="3361102125-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Tail</span><span class="p">.</span></code></pre><p>We must be careful how we use <code class="inline">++</code> in a loop. First is how not to use it:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_reverse</span><span class="p" data-group-id="9214644721-1">(</span><span class="p" data-group-id="9214644721-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9214644721-2">]</span><span class="p" data-group-id="9214644721-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">naive_reverse</span><span class="p" data-group-id="9214644721-3">(</span><span class="n">T</span><span class="p" data-group-id="9214644721-3">)</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9214644721-4">[</span><span class="n">H</span><span class="p" data-group-id="9214644721-4">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">naive_reverse</span><span class="p" data-group-id="9214644721-5">(</span><span class="p" data-group-id="9214644721-6">[</span><span class="p" data-group-id="9214644721-6">]</span><span class="p" data-group-id="9214644721-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9214644721-7">[</span><span class="p" data-group-id="9214644721-7">]</span><span class="p">.</span></code></pre><p>As the <code class="inline">++</code> operator copies its left-hand side operand, the growing
│ │ │ │ +result is copied repeatedly, leading to quadratic complexity.</p><p>On the other hand, using <code class="inline">++</code> in loop like this is perfectly fine:</p><p><strong>OK</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="3609793754-1">(</span><span class="n">List</span><span class="p" data-group-id="3609793754-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="3609793754-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3609793754-3">[</span><span class="p" data-group-id="3609793754-3">]</span><span class="p" data-group-id="3609793754-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="2959584156-4">(</span><span class="p" data-group-id="2959584156-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2959584156-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="2959584156-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="2959584156-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2959584156-7">[</span><span class="n">H</span><span class="p" data-group-id="2959584156-7">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="2959584156-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="2959584156-8">(</span><span class="p" data-group-id="2959584156-9">[</span><span class="p" data-group-id="2959584156-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="2959584156-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="3609793754-4">(</span><span class="p" data-group-id="3609793754-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3609793754-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3609793754-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="3609793754-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3609793754-7">[</span><span class="n">H</span><span class="p" data-group-id="3609793754-7">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3609793754-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="3609793754-8">(</span><span class="p" data-group-id="3609793754-9">[</span><span class="p" data-group-id="3609793754-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3609793754-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Each list element is copied only once. The growing result <code class="inline">Acc</code> is the right-hand
│ │ │ │ -side operand, which it is <em>not</em> copied.</p><p>Experienced Erlang programmers would probably write as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">vanilla_reverse</span><span class="p" data-group-id="6955103091-1">(</span><span class="p" data-group-id="6955103091-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6955103091-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6955103091-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="6955103091-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6955103091-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="6955103091-4">]</span><span class="p" data-group-id="6955103091-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="6955103091-5">(</span><span class="p" data-group-id="6955103091-6">[</span><span class="p" data-group-id="6955103091-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6955103091-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +side operand, which it is <em>not</em> copied.</p><p>Experienced Erlang programmers would probably write as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">vanilla_reverse</span><span class="p" data-group-id="5460378585-1">(</span><span class="p" data-group-id="5460378585-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5460378585-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="5460378585-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="5460378585-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5460378585-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="5460378585-4">]</span><span class="p" data-group-id="5460378585-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="5460378585-5">(</span><span class="p" data-group-id="5460378585-6">[</span><span class="p" data-group-id="5460378585-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="5460378585-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>In principle, this is slightly more efficient because the list element <code class="inline">[H]</code>
│ │ │ │  is not built before being copied and discarded. In practice, the compiler
│ │ │ │  rewrites <code class="inline">[H] ++ Acc</code> to <code class="inline">[H|Acc]</code>.</p><h2 id="timer-module" class="section-heading">
│ │ │ │    <a href="#timer-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Timer Module</span>
│ │ │ │ @@ -65,77 +65,77 @@
│ │ │ │  therefore harmless.</p><h2 id="accidental-copying-and-loss-of-sharing" class="section-heading">
│ │ │ │    <a href="#accidental-copying-and-loss-of-sharing" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Accidental Copying and Loss of Sharing</span>
│ │ │ │  </h2>
│ │ │ │  <p>When spawning a new process using a fun, one can accidentally copy more data to
│ │ │ │ -the process than intended. For example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental1</span><span class="p" data-group-id="6953407429-1">(</span><span class="n">State</span><span class="p" data-group-id="6953407429-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="6953407429-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6953407429-3">(</span><span class="p" data-group-id="6953407429-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6953407429-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6953407429-5">[</span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">info</span><span class="p" data-group-id="6953407429-5">]</span><span class="p" data-group-id="6953407429-4">)</span><span class="w">
│ │ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="6953407429-2">)</span><span class="p">.</span></code></pre><p>The code in the fun will extract one element from the record and print it. The
│ │ │ │ +the process than intended. For example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental1</span><span class="p" data-group-id="7353906059-1">(</span><span class="n">State</span><span class="p" data-group-id="7353906059-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7353906059-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7353906059-3">(</span><span class="p" data-group-id="7353906059-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7353906059-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7353906059-5">[</span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">info</span><span class="p" data-group-id="7353906059-5">]</span><span class="p" data-group-id="7353906059-4">)</span><span class="w">
│ │ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="7353906059-2">)</span><span class="p">.</span></code></pre><p>The code in the fun will extract one element from the record and print it. The
│ │ │ │  rest of the <code class="inline">state</code> record is not used. However, when the <a href="../../../lib/../erts/doc/html/erlang.html#spawn/1"><code class="inline">spawn/1</code></a>
│ │ │ │ -function is executed, the entire record is copied to the newly created process.</p><p>The same kind of problem can happen with a map:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental2</span><span class="p" data-group-id="0648981069-1">(</span><span class="n">State</span><span class="p" data-group-id="0648981069-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="0648981069-2">(</span><span class="nf">fun</span><span class="p" data-group-id="0648981069-3">(</span><span class="p" data-group-id="0648981069-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0648981069-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0648981069-5">[</span><span class="nf">map_get</span><span class="p" data-group-id="0648981069-6">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="0648981069-6">)</span><span class="p" data-group-id="0648981069-5">]</span><span class="p" data-group-id="0648981069-4">)</span><span class="w">
│ │ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="0648981069-2">)</span><span class="p">.</span></code></pre><p>In the following example (part of a module implementing the <a href="../../../lib/stdlib/doc/html/gen_server.html"><code class="inline">gen_server</code></a>
│ │ │ │ -behavior) the created fun is sent to another process:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="3632625472-1">(</span><span class="ss">give_me_a_fun</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3632625472-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3632625472-2">(</span><span class="p" data-group-id="3632625472-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="nb">size</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3632625472-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3632625472-3">}</span><span class="p">.</span></code></pre><p>How bad that unnecessary copy is depends on the contents of the record or the
│ │ │ │ -map.</p><p>For example, if the <code class="inline">state</code> record is initialized like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init1</span><span class="p" data-group-id="7237051738-1">(</span><span class="p" data-group-id="7237051738-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="7237051738-2">{</span><span class="ss">data</span><span class="o">=</span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="7237051738-3">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">10000</span><span class="p" data-group-id="7237051738-3">)</span><span class="p" data-group-id="7237051738-2">}</span><span class="p">.</span></code></pre><p>a list with 10000 elements (or about 20000 heap words) will be copied to the
│ │ │ │ +function is executed, the entire record is copied to the newly created process.</p><p>The same kind of problem can happen with a map:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental2</span><span class="p" data-group-id="9876577254-1">(</span><span class="n">State</span><span class="p" data-group-id="9876577254-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="9876577254-2">(</span><span class="nf">fun</span><span class="p" data-group-id="9876577254-3">(</span><span class="p" data-group-id="9876577254-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9876577254-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9876577254-5">[</span><span class="nf">map_get</span><span class="p" data-group-id="9876577254-6">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9876577254-6">)</span><span class="p" data-group-id="9876577254-5">]</span><span class="p" data-group-id="9876577254-4">)</span><span class="w">
│ │ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="9876577254-2">)</span><span class="p">.</span></code></pre><p>In the following example (part of a module implementing the <a href="../../../lib/stdlib/doc/html/gen_server.html"><code class="inline">gen_server</code></a>
│ │ │ │ +behavior) the created fun is sent to another process:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="3574913642-1">(</span><span class="ss">give_me_a_fun</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3574913642-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3574913642-2">(</span><span class="p" data-group-id="3574913642-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="nb">size</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3574913642-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3574913642-3">}</span><span class="p">.</span></code></pre><p>How bad that unnecessary copy is depends on the contents of the record or the
│ │ │ │ +map.</p><p>For example, if the <code class="inline">state</code> record is initialized like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init1</span><span class="p" data-group-id="9710782425-1">(</span><span class="p" data-group-id="9710782425-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="9710782425-2">{</span><span class="ss">data</span><span class="o">=</span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9710782425-3">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">10000</span><span class="p" data-group-id="9710782425-3">)</span><span class="p" data-group-id="9710782425-2">}</span><span class="p">.</span></code></pre><p>a list with 10000 elements (or about 20000 heap words) will be copied to the
│ │ │ │  newly created process.</p><p>An unnecessary copy of 10000 element list can be bad enough, but it can get even
│ │ │ │  worse if the <code class="inline">state</code> record contains <em>shared subterms</em>. Here is a simple example
│ │ │ │ -of a term with a shared subterm:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9928938811-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="9928938811-1">}</span></code></pre><p>When a term is copied to another process, sharing of subterms will be lost and
│ │ │ │ -the copied term can be many times larger than the original term. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init2</span><span class="p" data-group-id="2487312852-1">(</span><span class="p" data-group-id="2487312852-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">SharedSubTerms</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="2487312852-2">(</span><span class="nf">fun</span><span class="p" data-group-id="2487312852-3">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="2487312852-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2487312852-4">[</span><span class="n">A</span><span class="p">|</span><span class="n">A</span><span class="p" data-group-id="2487312852-4">]</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2487312852-5">[</span><span class="mi">0</span><span class="p" data-group-id="2487312852-5">]</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2487312852-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">15</span><span class="p" data-group-id="2487312852-6">)</span><span class="p" data-group-id="2487312852-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="2487312852-7">{</span><span class="ss">data</span><span class="o">=</span><span class="n">Shared</span><span class="p" data-group-id="2487312852-7">}</span><span class="p">.</span></code></pre><p>In the process that calls <code class="inline">init2/0</code>, the size of the <code class="inline">data</code> field in the <code class="inline">state</code>
│ │ │ │ +of a term with a shared subterm:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9743916094-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="9743916094-1">}</span></code></pre><p>When a term is copied to another process, sharing of subterms will be lost and
│ │ │ │ +the copied term can be many times larger than the original term. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init2</span><span class="p" data-group-id="6860863168-1">(</span><span class="p" data-group-id="6860863168-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">SharedSubTerms</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="6860863168-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6860863168-3">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="6860863168-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6860863168-4">[</span><span class="n">A</span><span class="p">|</span><span class="n">A</span><span class="p" data-group-id="6860863168-4">]</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6860863168-5">[</span><span class="mi">0</span><span class="p" data-group-id="6860863168-5">]</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="6860863168-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">15</span><span class="p" data-group-id="6860863168-6">)</span><span class="p" data-group-id="6860863168-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="6860863168-7">{</span><span class="ss">data</span><span class="o">=</span><span class="n">Shared</span><span class="p" data-group-id="6860863168-7">}</span><span class="p">.</span></code></pre><p>In the process that calls <code class="inline">init2/0</code>, the size of the <code class="inline">data</code> field in the <code class="inline">state</code>
│ │ │ │  record will be 32 heap words. When the record is copied to the newly created
│ │ │ │  process, sharing will be lost and the size of the copied <code class="inline">data</code> field will be
│ │ │ │  131070 heap words. More details about
│ │ │ │  <a href="eff_guide_processes.xhtml#loss-of-sharing">loss off sharing</a> are found in a later
│ │ │ │  section.</p><p>To avoid the problem, outside of the fun extract only the fields of the record
│ │ │ │ -that are actually used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental1</span><span class="p" data-group-id="5706251432-1">(</span><span class="n">State</span><span class="p" data-group-id="5706251432-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +that are actually used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental1</span><span class="p" data-group-id="1137648145-1">(</span><span class="n">State</span><span class="p" data-group-id="1137648145-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">info</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="5706251432-2">(</span><span class="nf">fun</span><span class="p" data-group-id="5706251432-3">(</span><span class="p" data-group-id="5706251432-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5706251432-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5706251432-5">[</span><span class="n">Info</span><span class="p" data-group-id="5706251432-5">]</span><span class="p" data-group-id="5706251432-4">)</span><span class="w">
│ │ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="5706251432-2">)</span><span class="p">.</span></code></pre><p>Similarly, outside of the fun extract only the map elements that are actually
│ │ │ │ -used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental2</span><span class="p" data-group-id="4309257758-1">(</span><span class="n">State</span><span class="p" data-group-id="4309257758-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">map_get</span><span class="p" data-group-id="4309257758-2">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4309257758-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="4309257758-3">(</span><span class="nf">fun</span><span class="p" data-group-id="4309257758-4">(</span><span class="p" data-group-id="4309257758-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4309257758-5">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4309257758-6">[</span><span class="n">Info</span><span class="p" data-group-id="4309257758-6">]</span><span class="p" data-group-id="4309257758-5">)</span><span class="w">
│ │ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="4309257758-3">)</span><span class="p">.</span></code></pre><h2 id="list_to_atom-1" class="section-heading">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1137648145-2">(</span><span class="nf">fun</span><span class="p" data-group-id="1137648145-3">(</span><span class="p" data-group-id="1137648145-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1137648145-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1137648145-5">[</span><span class="n">Info</span><span class="p" data-group-id="1137648145-5">]</span><span class="p" data-group-id="1137648145-4">)</span><span class="w">
│ │ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="1137648145-2">)</span><span class="p">.</span></code></pre><p>Similarly, outside of the fun extract only the map elements that are actually
│ │ │ │ +used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental2</span><span class="p" data-group-id="9494081826-1">(</span><span class="n">State</span><span class="p" data-group-id="9494081826-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">map_get</span><span class="p" data-group-id="9494081826-2">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9494081826-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="9494081826-3">(</span><span class="nf">fun</span><span class="p" data-group-id="9494081826-4">(</span><span class="p" data-group-id="9494081826-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9494081826-5">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9494081826-6">[</span><span class="n">Info</span><span class="p" data-group-id="9494081826-6">]</span><span class="p" data-group-id="9494081826-5">)</span><span class="w">
│ │ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="9494081826-3">)</span><span class="p">.</span></code></pre><h2 id="list_to_atom-1" class="section-heading">
│ │ │ │    <a href="#list_to_atom-1" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">list_to_atom/1</span>
│ │ │ │  </h2>
│ │ │ │  <p>Atoms are not garbage-collected. Once an atom is created, it is never removed.
│ │ │ │  The emulator terminates if the limit for the number of atoms (1,048,576 by
│ │ │ │  default) is reached.</p><p>Therefore, converting arbitrary input strings to atoms can be dangerous in a
│ │ │ │  system that runs continuously. If only certain well-defined atoms are allowed as
│ │ │ │  input, <a href="../../../lib/../erts/doc/html/erlang.html#list_to_existing_atom/1"><code class="inline">list_to_existing_atom/1</code></a> or
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#binary_to_existing_atom/1"><code class="inline">binary_to_existing_atom/1</code></a> can be used
│ │ │ │  to guard against a denial-of-service attack. (All atoms that are allowed must
│ │ │ │  have been created earlier, for example, by using all of them in a module
│ │ │ │  and loading that module.)</p><p>Using <a href="../../../lib/../erts/doc/html/erlang.html#list_to_atom/1"><code class="inline">list_to_atom/1</code></a> to construct an atom that
│ │ │ │ -is passed to <a href="../../../lib/../erts/doc/html/erlang.html#apply/3"><code class="inline">apply/3</code></a> is quite expensive.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">apply</span><span class="p" data-group-id="3111295290-1">(</span><span class="nf">list_to_atom</span><span class="p" data-group-id="3111295290-2">(</span><span class="s">&quot;some_prefix&quot;</span><span class="o">++</span><span class="n">Var</span><span class="p" data-group-id="3111295290-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="3111295290-1">)</span></code></pre><h2 id="length-1" class="section-heading">
│ │ │ │ +is passed to <a href="../../../lib/../erts/doc/html/erlang.html#apply/3"><code class="inline">apply/3</code></a> is quite expensive.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">apply</span><span class="p" data-group-id="4179906101-1">(</span><span class="nf">list_to_atom</span><span class="p" data-group-id="4179906101-2">(</span><span class="s">&quot;some_prefix&quot;</span><span class="o">++</span><span class="n">Var</span><span class="p" data-group-id="4179906101-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="4179906101-1">)</span></code></pre><h2 id="length-1" class="section-heading">
│ │ │ │    <a href="#length-1" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">length/1</span>
│ │ │ │  </h2>
│ │ │ │  <p>The time for calculating the length of a list is proportional to the length of
│ │ │ │  the list, as opposed to <a href="../../../lib/../erts/doc/html/erlang.html#tuple_size/1"><code class="inline">tuple_size/1</code></a>,
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#byte_size/1"><code class="inline">byte_size/1</code></a>, and <a href="../../../lib/../erts/doc/html/erlang.html#bit_size/1"><code class="inline">bit_size/1</code></a>, which all
│ │ │ │  execute in constant time.</p><p>Normally, there is no need to worry about the speed of <a href="../../../lib/../erts/doc/html/erlang.html#length/1"><code class="inline">length/1</code></a>,
│ │ │ │  because it is efficiently implemented in C. In time-critical code, you might
│ │ │ │  want to avoid it if the input list could potentially be very long.</p><p>Some uses of <a href="../../../lib/../erts/doc/html/erlang.html#length/1"><code class="inline">length/1</code></a> can be replaced by matching. For example,
│ │ │ │ -the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="4485445210-1">(</span><span class="n">L</span><span class="p" data-group-id="4485445210-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="4485445210-2">(</span><span class="n">L</span><span class="p" data-group-id="4485445210-2">)</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="2447495857-1">(</span><span class="p" data-group-id="2447495857-2">[</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="2447495857-2">]</span><span class="o">=</span><span class="n">L</span><span class="p" data-group-id="2447495857-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="1535683289-1">(</span><span class="n">L</span><span class="p" data-group-id="1535683289-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="1535683289-2">(</span><span class="n">L</span><span class="p" data-group-id="1535683289-2">)</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="0752895157-1">(</span><span class="p" data-group-id="0752895157-2">[</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="0752895157-2">]</span><span class="o">=</span><span class="n">L</span><span class="p" data-group-id="0752895157-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │     </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>One slight difference is that <a href="../../../lib/../erts/doc/html/erlang.html#length/1"><code class="inline">length(L)</code></a> fails if <code class="inline">L</code> is an
│ │ │ │  improper list, while the pattern in the second code fragment accepts an improper
│ │ │ │  list.</p><h2 id="setelement-3" class="section-heading">
│ │ │ │    <a href="#setelement-3" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">setelement/3</span>
│ │ │ │ @@ -143,18 +143,18 @@
│ │ │ │  <p><a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> copies the tuple it modifies. Therefore,
│ │ │ │  updating a tuple in a loop using <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> creates a new
│ │ │ │  copy of the tuple every time.</p><p>There is one exception to the rule that the tuple is copied. If the compiler
│ │ │ │  clearly can see that destructively updating the tuple would give the same result
│ │ │ │  as if the tuple was copied, the call to <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> is
│ │ │ │  replaced with a special destructive <code class="inline">setelement</code> instruction. In the following
│ │ │ │  code sequence, the first <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> call copies the tuple
│ │ │ │ -and modifies the ninth element:</p><pre><code class="makeup erlang" translate="no"><span class="nf">multiple_setelement</span><span class="p" data-group-id="3777122645-1">(</span><span class="n">T0</span><span class="p" data-group-id="3777122645-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="3777122645-2">(</span><span class="n">T0</span><span class="p" data-group-id="3777122645-2">)</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">9</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">T1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="3777122645-3">(</span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p" data-group-id="3777122645-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">T2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="3777122645-4">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="ss">foobar</span><span class="p" data-group-id="3777122645-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">setelement</span><span class="p" data-group-id="3777122645-5">(</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p">,</span><span class="w"> </span><span class="ss">new_value</span><span class="p" data-group-id="3777122645-5">)</span><span class="p">.</span></code></pre><p>The two following <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> calls modify the tuple in
│ │ │ │ +and modifies the ninth element:</p><pre><code class="makeup erlang" translate="no"><span class="nf">multiple_setelement</span><span class="p" data-group-id="8259223823-1">(</span><span class="n">T0</span><span class="p" data-group-id="8259223823-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="8259223823-2">(</span><span class="n">T0</span><span class="p" data-group-id="8259223823-2">)</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">9</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">T1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="8259223823-3">(</span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p" data-group-id="8259223823-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">T2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="8259223823-4">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="ss">foobar</span><span class="p" data-group-id="8259223823-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">setelement</span><span class="p" data-group-id="8259223823-5">(</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p">,</span><span class="w"> </span><span class="ss">new_value</span><span class="p" data-group-id="8259223823-5">)</span><span class="p">.</span></code></pre><p>The two following <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> calls modify the tuple in
│ │ │ │  place.</p><p>For the optimization to be applied, <em>all</em> the following conditions must be true:</p><ul><li>The tuple argument must be known to be a tuple of a known size.</li><li>The indices must be integer literals, not variables or expressions.</li><li>The indices must be given in descending order.</li><li>There must be no calls to another function in between the calls to
│ │ │ │  <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a>.</li><li>The tuple returned from one <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> call must only be
│ │ │ │  used in the subsequent call to <a href="../../../lib/../erts/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a>.</li></ul><p>If the code cannot be structured as in the <code class="inline">multiple_setelement/1</code> example, the
│ │ │ │  best way to modify multiple elements in a large tuple is to convert the tuple to
│ │ │ │  a list, modify the list, and convert it back to a tuple.</p><h2 id="size-1" class="section-heading">
│ │ │ │    <a href="#size-1" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ ├── OEBPS/code_loading.xhtml
│ │ │ │ @@ -27,16 +27,16 @@
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Compilation</span>
│ │ │ │  </h2>
│ │ │ │  <p>Erlang programs must be <em>compiled</em> to object code. The compiler can generate a
│ │ │ │  new file that contains the object code. The current abstract machine, which runs
│ │ │ │  the object code, is called BEAM, therefore the object files get the suffix
│ │ │ │ -<code class="inline">.beam</code>. The compiler can also generate a binary which can be loaded directly.</p><p>The compiler is located in the module <a href="../../../lib/compiler/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><pre><code class="makeup erlang" translate="no"><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="4333172388-1">(</span><span class="n">Module</span><span class="p" data-group-id="4333172388-1">)</span><span class="w">
│ │ │ │ -</span><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="4333172388-2">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="4333172388-2">)</span></code></pre><p>The Erlang shell understands the command <code class="inline">c(Module)</code>, which both compiles and
│ │ │ │ +<code class="inline">.beam</code>. The compiler can also generate a binary which can be loaded directly.</p><p>The compiler is located in the module <a href="../../../lib/compiler/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><pre><code class="makeup erlang" translate="no"><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="3054970475-1">(</span><span class="n">Module</span><span class="p" data-group-id="3054970475-1">)</span><span class="w">
│ │ │ │ +</span><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="3054970475-2">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="3054970475-2">)</span></code></pre><p>The Erlang shell understands the command <code class="inline">c(Module)</code>, which both compiles and
│ │ │ │  loads <code class="inline">Module</code>.</p><p>There is also a module <code class="inline">make</code>, which provides a set of functions similar to the
│ │ │ │  UNIX type Make functions, see module <a href="../../../lib/tools/doc/html/make.html"><code class="inline">make</code></a> in Tools.</p><p>The compiler can also be accessed from the OS prompt using the
│ │ │ │  <a href="../../../lib/../erts/doc/html/erl_cmd.xhtml">erl</a> executable in ERTS.</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -compile Module1...ModuleN</span><span class="w">
│ │ │ │  </span><span class="c1">% erl -make</span></code></pre><p>The <code class="inline">erlc</code> program provides way to compile modules from the OS
│ │ │ │  shell, see the <a href="../../../lib/../erts/doc/html/erlc_cmd.xhtml">erlc</a> executable in ERTS. It
│ │ │ │  understands a number of flags that can be used to define macros, add search
│ │ │ │  paths for include files, and more.</p><pre><code class="text">% erlc &lt;flags&gt; File1.erl...FileN.erl</code></pre><p><a href="" id="loading"></a></p><h2 id="code-loading" class="section-heading">
│ │ │ │ @@ -61,51 +61,51 @@
│ │ │ │  When a module is loaded into the system for the first time, the code becomes
│ │ │ │  'current'. If then a new instance of the module is loaded, the code of the
│ │ │ │  previous instance becomes 'old' and the new instance becomes 'current'.</p><p>Both old and current code is valid, and can be evaluated concurrently. Fully
│ │ │ │  qualified function calls always refer to current code. Old code can still be
│ │ │ │  evaluated because of processes lingering in the old code.</p><p>If a third instance of the module is loaded, the code server removes (purges)
│ │ │ │  the old code and any processes lingering in it is terminated. Then the third
│ │ │ │  instance becomes 'current' and the previously current code becomes 'old'.</p><p>To change from old code to current code, a process must make a fully qualified
│ │ │ │ -function call.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5148702962-1">(</span><span class="ss">m</span><span class="p" data-group-id="5148702962-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5148702962-2">(</span><span class="p" data-group-id="5148702962-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5148702962-3">]</span><span class="p" data-group-id="5148702962-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +function call.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8633021228-1">(</span><span class="ss">m</span><span class="p" data-group-id="8633021228-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8633021228-2">(</span><span class="p" data-group-id="8633021228-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8633021228-3">]</span><span class="p" data-group-id="8633021228-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="5148702962-4">(</span><span class="p" data-group-id="5148702962-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="8633021228-4">(</span><span class="p" data-group-id="8633021228-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │          </span><span class="ss">code_switch</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="nc">m</span><span class="p">:</span><span class="nf">loop</span><span class="p" data-group-id="5148702962-5">(</span><span class="p" data-group-id="5148702962-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +            </span><span class="nc">m</span><span class="p">:</span><span class="nf">loop</span><span class="p" data-group-id="8633021228-5">(</span><span class="p" data-group-id="8633021228-5">)</span><span class="p">;</span><span class="w">
│ │ │ │          </span><span class="n">Msg</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="5148702962-6">(</span><span class="p" data-group-id="5148702962-6">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="8633021228-6">(</span><span class="p" data-group-id="8633021228-6">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>To make the process change code, send the message <code class="inline">code_switch</code> to it. The
│ │ │ │  process then makes a fully qualified call to <code class="inline">m:loop()</code> and changes to current
│ │ │ │  code. Notice that <code class="inline">m:loop/0</code> must be exported.</p><p>For code replacement of funs to work, use the syntax
│ │ │ │  <code class="inline">fun Module:FunctionName/Arity</code>.</p><p><a href="" id="on_load"></a></p><h2 id="running-a-function-when-a-module-is-loaded" class="section-heading">
│ │ │ │    <a href="#running-a-function-when-a-module-is-loaded" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Running a Function When a Module is Loaded</span>
│ │ │ │  </h2>
│ │ │ │  <p>The <code class="inline">-on_load()</code> directive names a function that is to be run automatically when
│ │ │ │ -a module is loaded.</p><p>Its syntax is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="4392866900-1">(</span><span class="n">Name</span><span class="o">/</span><span class="mi">0</span><span class="p" data-group-id="4392866900-1">)</span><span class="p">.</span></code></pre><p>It is not necessary to export the function. It is called in a freshly spawned
│ │ │ │ +a module is loaded.</p><p>Its syntax is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="5378433469-1">(</span><span class="n">Name</span><span class="o">/</span><span class="mi">0</span><span class="p" data-group-id="5378433469-1">)</span><span class="p">.</span></code></pre><p>It is not necessary to export the function. It is called in a freshly spawned
│ │ │ │  process (which terminates as soon as the function returns).</p><p>The function must return <code class="inline">ok</code> if the module is to become the new current code
│ │ │ │  for the module and become callable.</p><p>Returning any other value or generating an exception causes the new code to be
│ │ │ │  unloaded. If the return value is not an atom, a warning error report is sent to
│ │ │ │  the error logger.</p><p>If there already is current code for the module, that code will remain current
│ │ │ │  and can be called until the <code class="inline">on_load</code> function has returned. If the <code class="inline">on_load</code>
│ │ │ │  function fails, the current code (if any) will remain current. If there is no
│ │ │ │  current code for a module, any process that makes an external call to the module
│ │ │ │  before the <code class="inline">on_load</code> function has finished will be suspended until the <code class="inline">on_load</code>
│ │ │ │  function have finished.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 19, if the <code class="inline">on_load</code> function failed, any previously current
│ │ │ │  code would become old, essentially leaving the system without any working and
│ │ │ │  reachable instance of the module.</p></section><p>In embedded mode, first all modules are loaded. Then all <code class="inline">on_load</code> functions are
│ │ │ │  called. The system is terminated unless all of the <code class="inline">on_load</code> functions return
│ │ │ │ -<code class="inline">ok</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5403357476-1">(</span><span class="ss">m</span><span class="p" data-group-id="5403357476-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="5403357476-2">(</span><span class="ss">load_my_nifs</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5403357476-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<code class="inline">ok</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3276361441-1">(</span><span class="ss">m</span><span class="p" data-group-id="3276361441-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="3276361441-2">(</span><span class="ss">load_my_nifs</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3276361441-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">load_my_nifs</span><span class="p" data-group-id="5403357476-3">(</span><span class="p" data-group-id="5403357476-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">load_my_nifs</span><span class="p" data-group-id="3276361441-3">(</span><span class="p" data-group-id="3276361441-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">NifPath</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">    </span><span class="c1">%Set up the path to the NIF library.</span><span class="w">
│ │ │ │      </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">       </span><span class="c1">%Initialize the Info term</span><span class="w">
│ │ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="5403357476-4">(</span><span class="n">NifPath</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="5403357476-4">)</span><span class="p">.</span></code></pre><p>If the call to <a href="../../../lib/../erts/doc/html/erlang.html#load_nif/2"><code class="inline">erlang:load_nif/2</code></a> fails, the module is unloaded and a warning
│ │ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="3276361441-4">(</span><span class="n">NifPath</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="3276361441-4">)</span><span class="p">.</span></code></pre><p>If the call to <a href="../../../lib/../erts/doc/html/erlang.html#load_nif/2"><code class="inline">erlang:load_nif/2</code></a> fails, the module is unloaded and a warning
│ │ │ │  report is sent to the error loader.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/c_portdriver.xhtml
│ │ │ │ @@ -56,112 +56,112 @@
│ │ │ │  <p>Like a port program, the port communicates with an Erlang process. All
│ │ │ │  communication goes through one Erlang process that is the <em>connected process</em> of
│ │ │ │  the port driver. Terminating this process closes the port driver.</p><p>Before the port is created, the driver must be loaded. This is done with the
│ │ │ │  function <a href="../../../lib/kernel/doc/html/erl_ddll.html#load_driver/2"><code class="inline">erl_ddll:load_driver/2</code></a>, with the name of the shared library as
│ │ │ │  argument.</p><p>The port is then created using the BIF <a href="../../../lib/../erts/doc/html/erlang.html#open_port/2"><code class="inline">open_port/2</code></a>, with the
│ │ │ │  tuple <code class="inline">{spawn, DriverName}</code> as the first argument. The string <code class="inline">SharedLib</code> is the
│ │ │ │  name of the port driver. The second argument is a list of options, none in this
│ │ │ │ -case:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4536142020-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="4536142020-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4536142020-2">(</span><span class="p" data-group-id="4536142020-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4536142020-3">]</span><span class="p" data-group-id="4536142020-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +case:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1309933580-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="1309933580-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1309933580-2">(</span><span class="p" data-group-id="1309933580-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1309933580-3">]</span><span class="p" data-group-id="1309933580-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="4536142020-4">(</span><span class="n">SharedLib</span><span class="p" data-group-id="4536142020-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="4536142020-5">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="4536142020-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1309933580-4">(</span><span class="n">SharedLib</span><span class="p" data-group-id="1309933580-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="1309933580-5">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="1309933580-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │          </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4536142020-6">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="4536142020-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="4536142020-7">(</span><span class="p" data-group-id="4536142020-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="4536142020-8">}</span><span class="p" data-group-id="4536142020-7">)</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="1309933580-6">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="1309933580-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="1309933580-7">(</span><span class="p" data-group-id="1309933580-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="1309933580-8">}</span><span class="p" data-group-id="1309933580-7">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="4536142020-9">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4536142020-10">[</span><span class="n">SharedLib</span><span class="p" data-group-id="4536142020-10">]</span><span class="p" data-group-id="4536142020-9">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1309933580-9">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1309933580-10">[</span><span class="n">SharedLib</span><span class="p" data-group-id="1309933580-10">]</span><span class="p" data-group-id="1309933580-9">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="4536142020-11">(</span><span class="n">SharedLib</span><span class="p" data-group-id="4536142020-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="nf">register</span><span class="p" data-group-id="4536142020-12">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4536142020-13">(</span><span class="p" data-group-id="4536142020-13">)</span><span class="p" data-group-id="4536142020-12">)</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="4536142020-14">(</span><span class="p" data-group-id="4536142020-15">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="4536142020-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4536142020-16">[</span><span class="p" data-group-id="4536142020-16">]</span><span class="p" data-group-id="4536142020-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="nf">loop</span><span class="p" data-group-id="4536142020-17">(</span><span class="n">Port</span><span class="p" data-group-id="4536142020-17">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex5:foo/1</code> and <code class="inline">complex5:bar/1</code> can be implemented. Both send a
│ │ │ │ -message to the <code class="inline">complex</code> process and receive the following reply:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="4580365043-1">(</span><span class="n">X</span><span class="p" data-group-id="4580365043-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="4580365043-2">(</span><span class="p" data-group-id="4580365043-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4580365043-3">}</span><span class="p" data-group-id="4580365043-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="4580365043-4">(</span><span class="n">Y</span><span class="p" data-group-id="4580365043-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="4580365043-5">(</span><span class="p" data-group-id="4580365043-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4580365043-6">}</span><span class="p" data-group-id="4580365043-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="1309933580-11">(</span><span class="n">SharedLib</span><span class="p" data-group-id="1309933580-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="nf">register</span><span class="p" data-group-id="1309933580-12">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1309933580-13">(</span><span class="p" data-group-id="1309933580-13">)</span><span class="p" data-group-id="1309933580-12">)</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="1309933580-14">(</span><span class="p" data-group-id="1309933580-15">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="1309933580-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1309933580-16">[</span><span class="p" data-group-id="1309933580-16">]</span><span class="p" data-group-id="1309933580-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="nf">loop</span><span class="p" data-group-id="1309933580-17">(</span><span class="n">Port</span><span class="p" data-group-id="1309933580-17">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex5:foo/1</code> and <code class="inline">complex5:bar/1</code> can be implemented. Both send a
│ │ │ │ +message to the <code class="inline">complex</code> process and receive the following reply:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="3638510338-1">(</span><span class="n">X</span><span class="p" data-group-id="3638510338-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="3638510338-2">(</span><span class="p" data-group-id="3638510338-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3638510338-3">}</span><span class="p" data-group-id="3638510338-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="3638510338-4">(</span><span class="n">Y</span><span class="p" data-group-id="3638510338-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="3638510338-5">(</span><span class="p" data-group-id="3638510338-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3638510338-6">}</span><span class="p" data-group-id="3638510338-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="4580365043-7">(</span><span class="n">Msg</span><span class="p" data-group-id="4580365043-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4580365043-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4580365043-9">(</span><span class="p" data-group-id="4580365043-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4580365043-8">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="3638510338-7">(</span><span class="n">Msg</span><span class="p" data-group-id="3638510338-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3638510338-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3638510338-9">(</span><span class="p" data-group-id="3638510338-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="3638510338-8">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4580365043-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4580365043-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="3638510338-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="3638510338-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="n">Result</span><span class="w">
│ │ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process performs the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="5111806275-1">(</span><span class="n">Port</span><span class="p" data-group-id="5111806275-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process performs the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="1661193147-1">(</span><span class="n">Port</span><span class="p" data-group-id="1661193147-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="5111806275-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5111806275-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -            </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5111806275-3">{</span><span class="nf">self</span><span class="p" data-group-id="5111806275-4">(</span><span class="p" data-group-id="5111806275-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5111806275-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="5111806275-6">(</span><span class="n">Msg</span><span class="p" data-group-id="5111806275-6">)</span><span class="p" data-group-id="5111806275-5">}</span><span class="p" data-group-id="5111806275-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="1661193147-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1661193147-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +            </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1661193147-3">{</span><span class="nf">self</span><span class="p" data-group-id="1661193147-4">(</span><span class="p" data-group-id="1661193147-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1661193147-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="1661193147-6">(</span><span class="n">Msg</span><span class="p" data-group-id="1661193147-6">)</span><span class="p" data-group-id="1661193147-5">}</span><span class="p" data-group-id="1661193147-3">}</span><span class="p">,</span><span class="w">
│ │ │ │              </span><span class="k">receive</span><span class="w">
│ │ │ │ -                </span><span class="p" data-group-id="5111806275-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5111806275-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5111806275-8">}</span><span class="p" data-group-id="5111806275-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -                    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5111806275-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="5111806275-10">(</span><span class="n">Data</span><span class="p" data-group-id="5111806275-10">)</span><span class="p" data-group-id="5111806275-9">}</span><span class="w">
│ │ │ │ +                </span><span class="p" data-group-id="1661193147-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1661193147-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1661193147-8">}</span><span class="p" data-group-id="1661193147-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +                    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1661193147-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="1661193147-10">(</span><span class="n">Data</span><span class="p" data-group-id="1661193147-10">)</span><span class="p" data-group-id="1661193147-9">}</span><span class="w">
│ │ │ │              </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="5111806275-11">(</span><span class="n">Port</span><span class="p" data-group-id="5111806275-11">)</span><span class="w">
│ │ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="1661193147-11">(</span><span class="n">Port</span><span class="p" data-group-id="1661193147-11">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Assuming that both the arguments and the results from the C functions are less
│ │ │ │  than 256, a simple encoding/decoding scheme is employed. In this scheme, <code class="inline">foo</code>
│ │ │ │  is represented by byte 1, <code class="inline">bar</code> is represented by 2, and the argument/result is
│ │ │ │ -represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="8200267802-1">(</span><span class="p" data-group-id="8200267802-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8200267802-2">}</span><span class="p" data-group-id="8200267802-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8200267802-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8200267802-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="8200267802-4">(</span><span class="p" data-group-id="8200267802-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8200267802-5">}</span><span class="p" data-group-id="8200267802-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8200267802-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8200267802-6">]</span><span class="p">.</span><span class="w">
│ │ │ │ +represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="7783495036-1">(</span><span class="p" data-group-id="7783495036-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7783495036-2">}</span><span class="p" data-group-id="7783495036-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7783495036-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7783495036-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="7783495036-4">(</span><span class="p" data-group-id="7783495036-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7783495036-5">}</span><span class="p" data-group-id="7783495036-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7783495036-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7783495036-6">]</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="8200267802-7">(</span><span class="p" data-group-id="8200267802-8">[</span><span class="n">Int</span><span class="p" data-group-id="8200267802-8">]</span><span class="p" data-group-id="8200267802-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functions for stopping the port and
│ │ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="7783495036-7">(</span><span class="p" data-group-id="7783495036-8">[</span><span class="n">Int</span><span class="p" data-group-id="7783495036-8">]</span><span class="p" data-group-id="7783495036-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functions for stopping the port and
│ │ │ │  detecting port failures, is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7526375015-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="7526375015-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7526375015-2">(</span><span class="p" data-group-id="7526375015-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7526375015-3">]</span><span class="p" data-group-id="7526375015-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7526375015-4">(</span><span class="p" data-group-id="7526375015-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7526375015-5">]</span><span class="p" data-group-id="7526375015-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2653040723-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="2653040723-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2653040723-2">(</span><span class="p" data-group-id="2653040723-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2653040723-3">]</span><span class="p" data-group-id="2653040723-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2653040723-4">(</span><span class="p" data-group-id="2653040723-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2653040723-5">]</span><span class="p" data-group-id="2653040723-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="7526375015-6">(</span><span class="n">SharedLib</span><span class="p" data-group-id="7526375015-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="7526375015-7">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="7526375015-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="2653040723-6">(</span><span class="n">SharedLib</span><span class="p" data-group-id="2653040723-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="2653040723-7">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="2653040723-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │  	</span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="7526375015-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="7526375015-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ -	</span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="7526375015-9">(</span><span class="p" data-group-id="7526375015-10">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="7526375015-10">}</span><span class="p" data-group-id="7526375015-9">)</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="2653040723-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="2653040723-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ │ +	</span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="2653040723-9">(</span><span class="p" data-group-id="2653040723-10">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="2653040723-10">}</span><span class="p" data-group-id="2653040723-9">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="7526375015-11">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7526375015-12">[</span><span class="n">SharedLib</span><span class="p" data-group-id="7526375015-12">]</span><span class="p" data-group-id="7526375015-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="2653040723-11">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2653040723-12">[</span><span class="n">SharedLib</span><span class="p" data-group-id="2653040723-12">]</span><span class="p" data-group-id="2653040723-11">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="7526375015-13">(</span><span class="n">SharedLib</span><span class="p" data-group-id="7526375015-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="7526375015-14">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7526375015-15">(</span><span class="p" data-group-id="7526375015-15">)</span><span class="p" data-group-id="7526375015-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="7526375015-16">(</span><span class="p" data-group-id="7526375015-17">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="7526375015-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7526375015-18">[</span><span class="p" data-group-id="7526375015-18">]</span><span class="p" data-group-id="7526375015-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="7526375015-19">(</span><span class="n">Port</span><span class="p" data-group-id="7526375015-19">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="2653040723-13">(</span><span class="n">SharedLib</span><span class="p" data-group-id="2653040723-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="2653040723-14">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2653040723-15">(</span><span class="p" data-group-id="2653040723-15">)</span><span class="p" data-group-id="2653040723-14">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="2653040723-16">(</span><span class="p" data-group-id="2653040723-17">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="2653040723-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2653040723-18">[</span><span class="p" data-group-id="2653040723-18">]</span><span class="p" data-group-id="2653040723-16">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="2653040723-19">(</span><span class="n">Port</span><span class="p" data-group-id="2653040723-19">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="7526375015-20">(</span><span class="p" data-group-id="7526375015-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="2653040723-20">(</span><span class="p" data-group-id="2653040723-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="7526375015-21">(</span><span class="n">X</span><span class="p" data-group-id="7526375015-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="7526375015-22">(</span><span class="p" data-group-id="7526375015-23">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7526375015-23">}</span><span class="p" data-group-id="7526375015-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="7526375015-24">(</span><span class="n">Y</span><span class="p" data-group-id="7526375015-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="7526375015-25">(</span><span class="p" data-group-id="7526375015-26">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7526375015-26">}</span><span class="p" data-group-id="7526375015-25">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="2653040723-21">(</span><span class="n">X</span><span class="p" data-group-id="2653040723-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="2653040723-22">(</span><span class="p" data-group-id="2653040723-23">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2653040723-23">}</span><span class="p" data-group-id="2653040723-22">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="2653040723-24">(</span><span class="n">Y</span><span class="p" data-group-id="2653040723-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="2653040723-25">(</span><span class="p" data-group-id="2653040723-26">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2653040723-26">}</span><span class="p" data-group-id="2653040723-25">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="7526375015-27">(</span><span class="n">Msg</span><span class="p" data-group-id="7526375015-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7526375015-28">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7526375015-29">(</span><span class="p" data-group-id="7526375015-29">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7526375015-28">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="2653040723-27">(</span><span class="n">Msg</span><span class="p" data-group-id="2653040723-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2653040723-28">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2653040723-29">(</span><span class="p" data-group-id="2653040723-29">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2653040723-28">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="7526375015-30">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7526375015-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="2653040723-30">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="2653040723-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="7526375015-31">(</span><span class="n">Port</span><span class="p" data-group-id="7526375015-31">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="2653040723-31">(</span><span class="n">Port</span><span class="p" data-group-id="2653040723-31">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="7526375015-32">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7526375015-32">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7526375015-33">{</span><span class="nf">self</span><span class="p" data-group-id="7526375015-34">(</span><span class="p" data-group-id="7526375015-34">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7526375015-35">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="7526375015-36">(</span><span class="n">Msg</span><span class="p" data-group-id="7526375015-36">)</span><span class="p" data-group-id="7526375015-35">}</span><span class="p" data-group-id="7526375015-33">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="2653040723-32">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2653040723-32">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2653040723-33">{</span><span class="nf">self</span><span class="p" data-group-id="2653040723-34">(</span><span class="p" data-group-id="2653040723-34">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2653040723-35">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="2653040723-36">(</span><span class="n">Msg</span><span class="p" data-group-id="2653040723-36">)</span><span class="p" data-group-id="2653040723-35">}</span><span class="p" data-group-id="2653040723-33">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="7526375015-37">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7526375015-38">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7526375015-38">}</span><span class="p" data-group-id="7526375015-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7526375015-39">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="7526375015-40">(</span><span class="n">Data</span><span class="p" data-group-id="7526375015-40">)</span><span class="p" data-group-id="7526375015-39">}</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="2653040723-37">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2653040723-38">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2653040723-38">}</span><span class="p" data-group-id="2653040723-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2653040723-39">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="2653040723-40">(</span><span class="n">Data</span><span class="p" data-group-id="2653040723-40">)</span><span class="p" data-group-id="2653040723-39">}</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="7526375015-41">(</span><span class="n">Port</span><span class="p" data-group-id="7526375015-41">)</span><span class="p">;</span><span class="w">
│ │ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="2653040723-41">(</span><span class="n">Port</span><span class="p" data-group-id="2653040723-41">)</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7526375015-42">{</span><span class="nf">self</span><span class="p" data-group-id="7526375015-43">(</span><span class="p" data-group-id="7526375015-43">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="7526375015-42">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2653040723-42">{</span><span class="nf">self</span><span class="p" data-group-id="2653040723-43">(</span><span class="p" data-group-id="2653040723-43">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="2653040723-42">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="7526375015-44">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="7526375015-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="7526375015-45">(</span><span class="ss">normal</span><span class="p" data-group-id="7526375015-45">)</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="2653040723-44">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="2653040723-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="2653040723-45">(</span><span class="ss">normal</span><span class="p" data-group-id="2653040723-45">)</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="7526375015-46">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="7526375015-46">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7526375015-47">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7526375015-48">[</span><span class="n">Reason</span><span class="p" data-group-id="7526375015-48">]</span><span class="p" data-group-id="7526375015-47">)</span><span class="p">,</span><span class="w">
│ │ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="7526375015-49">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="7526375015-49">)</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="2653040723-46">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2653040723-46">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2653040723-47">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2653040723-48">[</span><span class="n">Reason</span><span class="p" data-group-id="2653040723-48">]</span><span class="p" data-group-id="2653040723-47">)</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="2653040723-49">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="2653040723-49">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="7526375015-50">(</span><span class="p" data-group-id="7526375015-51">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7526375015-51">}</span><span class="p" data-group-id="7526375015-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7526375015-52">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7526375015-52">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="7526375015-53">(</span><span class="p" data-group-id="7526375015-54">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7526375015-54">}</span><span class="p" data-group-id="7526375015-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7526375015-55">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7526375015-55">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="2653040723-50">(</span><span class="p" data-group-id="2653040723-51">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2653040723-51">}</span><span class="p" data-group-id="2653040723-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2653040723-52">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2653040723-52">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="2653040723-53">(</span><span class="p" data-group-id="2653040723-54">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2653040723-54">}</span><span class="p" data-group-id="2653040723-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2653040723-55">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2653040723-55">]</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="7526375015-56">(</span><span class="p" data-group-id="7526375015-57">[</span><span class="n">Int</span><span class="p" data-group-id="7526375015-57">]</span><span class="p" data-group-id="7526375015-56">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-driver" class="section-heading">
│ │ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="2653040723-56">(</span><span class="p" data-group-id="2653040723-57">[</span><span class="n">Int</span><span class="p" data-group-id="2653040723-57">]</span><span class="p" data-group-id="2653040723-56">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-driver" class="section-heading">
│ │ │ │    <a href="#c-driver" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">C Driver</span>
│ │ │ │  </h2>
│ │ │ │  <p>The C driver is a module that is compiled and linked into a shared library. It
│ │ │ │  uses a driver structure and includes the header file <code class="inline">erl_driver.h</code>.</p><p>The driver structure is filled with the driver name and function pointers. It is
│ │ │ │ @@ -252,22 +252,22 @@
│ │ │ │    <a href="#running-the-example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Running the Example</span>
│ │ │ │  </h2>
│ │ │ │  <p><em>Step 1.</em> Compile the C code:</p><pre><code class="text">unix&gt; gcc -o example_drv.so -fpic -shared complex.c port_driver.c
│ │ │ │  windows&gt; cl -LD -MD -Fe example_drv.dll complex.c port_driver.c</code></pre><p><em>Step 2.</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="ss">erl</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="3302820651-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="3302820651-1">]</span><span class="w"> </span><span class="p" data-group-id="3302820651-2">[</span><span class="ss">source</span><span class="p" data-group-id="3302820651-2">]</span><span class="w"> </span><span class="p" data-group-id="3302820651-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="3302820651-3">]</span><span class="w"> </span><span class="p" data-group-id="3302820651-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3302820651-4">]</span><span class="w"> </span><span class="p" data-group-id="3302820651-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="3302820651-5">]</span><span class="w"> </span><span class="p" data-group-id="3302820651-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3302820651-6">]</span><span class="w"> </span><span class="p" data-group-id="3302820651-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="3302820651-7">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="5869937259-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="5869937259-1">]</span><span class="w"> </span><span class="p" data-group-id="5869937259-2">[</span><span class="ss">source</span><span class="p" data-group-id="5869937259-2">]</span><span class="w"> </span><span class="p" data-group-id="5869937259-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="5869937259-3">]</span><span class="w"> </span><span class="p" data-group-id="5869937259-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="5869937259-4">]</span><span class="w"> </span><span class="p" data-group-id="5869937259-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="5869937259-5">]</span><span class="w"> </span><span class="p" data-group-id="5869937259-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="5869937259-6">]</span><span class="w"> </span><span class="p" data-group-id="5869937259-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="5869937259-7">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="3302820651-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="3302820651-9">(</span><span class="p" data-group-id="3302820651-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="3302820651-8">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="3302820651-10">(</span><span class="ss">complex5</span><span class="p" data-group-id="3302820651-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3302820651-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex5</span><span class="p" data-group-id="3302820651-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="3906018270-1">(</span><span class="s">&quot;example_drv&quot;</span><span class="p" data-group-id="3906018270-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="5869937259-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="5869937259-9">(</span><span class="p" data-group-id="5869937259-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="5869937259-8">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="5869937259-10">(</span><span class="ss">complex5</span><span class="p" data-group-id="5869937259-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5869937259-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex5</span><span class="p" data-group-id="5869937259-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="1085123437-1">(</span><span class="s">&quot;example_drv&quot;</span><span class="p" data-group-id="1085123437-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.34</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="3906018270-2">(</span><span class="mi">3</span><span class="p" data-group-id="3906018270-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="1085123437-2">(</span><span class="mi">3</span><span class="p" data-group-id="1085123437-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="3906018270-3">(</span><span class="mi">5</span><span class="p" data-group-id="3906018270-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="1085123437-3">(</span><span class="mi">5</span><span class="p" data-group-id="1085123437-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="3906018270-4">(</span><span class="p" data-group-id="3906018270-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="1085123437-4">(</span><span class="p" data-group-id="1085123437-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">stop</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/c_port.xhtml
│ │ │ │ @@ -53,101 +53,101 @@
│ │ │ │  external program, if it is written properly).</p><p>The port is created using the BIF <a href="../../../lib/../erts/doc/html/erlang.html#open_port/2"><code class="inline">open_port/2</code></a> with
│ │ │ │  <code class="inline">{spawn,ExtPrg}</code> as the first argument. The string <code class="inline">ExtPrg</code> is the name of the
│ │ │ │  external program, including any command line arguments. The second argument is a
│ │ │ │  list of options, in this case only <code class="inline">{packet,2}</code>. This option says that a 2 byte
│ │ │ │  length indicator is to be used to simplify the communication between C and
│ │ │ │  Erlang. The Erlang port automatically adds the length indicator, but this must
│ │ │ │  be done explicitly in the external C program.</p><p>The process is also set to trap exits, which enables detection of failure of the
│ │ │ │ -external program:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5011138170-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="5011138170-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5011138170-2">(</span><span class="p" data-group-id="5011138170-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5011138170-3">]</span><span class="p" data-group-id="5011138170-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +external program:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8311512093-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="8311512093-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8311512093-2">(</span><span class="p" data-group-id="8311512093-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8311512093-3">]</span><span class="p" data-group-id="8311512093-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="5011138170-4">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="5011138170-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="nf">spawn</span><span class="p" data-group-id="5011138170-5">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5011138170-6">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="5011138170-6">]</span><span class="p" data-group-id="5011138170-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="8311512093-4">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="8311512093-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="nf">spawn</span><span class="p" data-group-id="8311512093-5">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8311512093-6">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="8311512093-6">]</span><span class="p" data-group-id="8311512093-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="5011138170-7">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="5011138170-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="nf">register</span><span class="p" data-group-id="5011138170-8">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5011138170-9">(</span><span class="p" data-group-id="5011138170-9">)</span><span class="p" data-group-id="5011138170-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="nf">process_flag</span><span class="p" data-group-id="5011138170-10">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5011138170-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="5011138170-11">(</span><span class="p" data-group-id="5011138170-12">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="5011138170-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5011138170-13">[</span><span class="p" data-group-id="5011138170-14">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="5011138170-14">}</span><span class="p" data-group-id="5011138170-13">]</span><span class="p" data-group-id="5011138170-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="nf">loop</span><span class="p" data-group-id="5011138170-15">(</span><span class="n">Port</span><span class="p" data-group-id="5011138170-15">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex1:foo/1</code> and <code class="inline">complex1:bar/1</code> can be implemented. Both send a
│ │ │ │ -message to the <code class="inline">complex</code> process and receive the following replies:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="5990230263-1">(</span><span class="n">X</span><span class="p" data-group-id="5990230263-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="nf">call_port</span><span class="p" data-group-id="5990230263-2">(</span><span class="p" data-group-id="5990230263-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="5990230263-3">}</span><span class="p" data-group-id="5990230263-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="5990230263-4">(</span><span class="n">Y</span><span class="p" data-group-id="5990230263-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="nf">call_port</span><span class="p" data-group-id="5990230263-5">(</span><span class="p" data-group-id="5990230263-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5990230263-6">}</span><span class="p" data-group-id="5990230263-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="8311512093-7">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="8311512093-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="nf">register</span><span class="p" data-group-id="8311512093-8">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8311512093-9">(</span><span class="p" data-group-id="8311512093-9">)</span><span class="p" data-group-id="8311512093-8">)</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="nf">process_flag</span><span class="p" data-group-id="8311512093-10">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8311512093-10">)</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="8311512093-11">(</span><span class="p" data-group-id="8311512093-12">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="8311512093-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8311512093-13">[</span><span class="p" data-group-id="8311512093-14">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="8311512093-14">}</span><span class="p" data-group-id="8311512093-13">]</span><span class="p" data-group-id="8311512093-11">)</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="nf">loop</span><span class="p" data-group-id="8311512093-15">(</span><span class="n">Port</span><span class="p" data-group-id="8311512093-15">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex1:foo/1</code> and <code class="inline">complex1:bar/1</code> can be implemented. Both send a
│ │ │ │ +message to the <code class="inline">complex</code> process and receive the following replies:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="7625713394-1">(</span><span class="n">X</span><span class="p" data-group-id="7625713394-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="nf">call_port</span><span class="p" data-group-id="7625713394-2">(</span><span class="p" data-group-id="7625713394-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7625713394-3">}</span><span class="p" data-group-id="7625713394-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="7625713394-4">(</span><span class="n">Y</span><span class="p" data-group-id="7625713394-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="nf">call_port</span><span class="p" data-group-id="7625713394-5">(</span><span class="p" data-group-id="7625713394-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7625713394-6">}</span><span class="p" data-group-id="7625713394-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="5990230263-7">(</span><span class="n">Msg</span><span class="p" data-group-id="5990230263-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -  </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5990230263-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5990230263-9">(</span><span class="p" data-group-id="5990230263-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5990230263-8">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="7625713394-7">(</span><span class="n">Msg</span><span class="p" data-group-id="7625713394-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7625713394-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7625713394-9">(</span><span class="p" data-group-id="7625713394-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7625713394-8">}</span><span class="p">,</span><span class="w">
│ │ │ │    </span><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5990230263-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="5990230263-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7625713394-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7625713394-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │        </span><span class="n">Result</span><span class="w">
│ │ │ │ -  </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process does the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="0130628506-1">(</span><span class="n">Port</span><span class="p" data-group-id="0130628506-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +  </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process does the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="8209457465-1">(</span><span class="n">Port</span><span class="p" data-group-id="8209457465-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │    </span><span class="k">receive</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0130628506-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="0130628506-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -      </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0130628506-3">{</span><span class="nf">self</span><span class="p" data-group-id="0130628506-4">(</span><span class="p" data-group-id="0130628506-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0130628506-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="0130628506-6">(</span><span class="n">Msg</span><span class="p" data-group-id="0130628506-6">)</span><span class="p" data-group-id="0130628506-5">}</span><span class="p" data-group-id="0130628506-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8209457465-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="8209457465-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +      </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8209457465-3">{</span><span class="nf">self</span><span class="p" data-group-id="8209457465-4">(</span><span class="p" data-group-id="8209457465-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8209457465-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="8209457465-6">(</span><span class="n">Msg</span><span class="p" data-group-id="8209457465-6">)</span><span class="p" data-group-id="8209457465-5">}</span><span class="p" data-group-id="8209457465-3">}</span><span class="p">,</span><span class="w">
│ │ │ │        </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="0130628506-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0130628506-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0130628506-8">}</span><span class="p" data-group-id="0130628506-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -          </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0130628506-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="0130628506-10">(</span><span class="n">Data</span><span class="p" data-group-id="0130628506-10">)</span><span class="p" data-group-id="0130628506-9">}</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="8209457465-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8209457465-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8209457465-8">}</span><span class="p" data-group-id="8209457465-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +          </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8209457465-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="8209457465-10">(</span><span class="n">Data</span><span class="p" data-group-id="8209457465-10">)</span><span class="p" data-group-id="8209457465-9">}</span><span class="w">
│ │ │ │        </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -      </span><span class="nf">loop</span><span class="p" data-group-id="0130628506-11">(</span><span class="n">Port</span><span class="p" data-group-id="0130628506-11">)</span><span class="w">
│ │ │ │ +      </span><span class="nf">loop</span><span class="p" data-group-id="8209457465-11">(</span><span class="n">Port</span><span class="p" data-group-id="8209457465-11">)</span><span class="w">
│ │ │ │    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Assuming that both the arguments and the results from the C functions are less
│ │ │ │  than 256, a simple encoding/decoding scheme is employed. In this scheme, <code class="inline">foo</code>
│ │ │ │  is represented by byte 1, <code class="inline">bar</code> is represented by 2, and the argument/result is
│ │ │ │ -represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="8193612444-1">(</span><span class="p" data-group-id="8193612444-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8193612444-2">}</span><span class="p" data-group-id="8193612444-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8193612444-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8193612444-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="8193612444-4">(</span><span class="p" data-group-id="8193612444-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8193612444-5">}</span><span class="p" data-group-id="8193612444-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8193612444-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8193612444-6">]</span><span class="p">.</span><span class="w">
│ │ │ │ +represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="2879199416-1">(</span><span class="p" data-group-id="2879199416-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2879199416-2">}</span><span class="p" data-group-id="2879199416-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2879199416-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2879199416-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="2879199416-4">(</span><span class="p" data-group-id="2879199416-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2879199416-5">}</span><span class="p" data-group-id="2879199416-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2879199416-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2879199416-6">]</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="8193612444-7">(</span><span class="p" data-group-id="8193612444-8">[</span><span class="n">Int</span><span class="p" data-group-id="8193612444-8">]</span><span class="p" data-group-id="8193612444-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functionality for stopping the port and
│ │ │ │ -detecting port failures, is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9970460223-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="9970460223-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9970460223-2">(</span><span class="p" data-group-id="9970460223-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9970460223-3">]</span><span class="p" data-group-id="9970460223-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9970460223-4">(</span><span class="p" data-group-id="9970460223-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9970460223-5">]</span><span class="p" data-group-id="9970460223-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ -
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="9970460223-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="9970460223-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="9970460223-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9970460223-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="9970460223-8">]</span><span class="p" data-group-id="9970460223-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="9970460223-9">(</span><span class="p" data-group-id="9970460223-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="2879199416-7">(</span><span class="p" data-group-id="2879199416-8">[</span><span class="n">Int</span><span class="p" data-group-id="2879199416-8">]</span><span class="p" data-group-id="2879199416-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functionality for stopping the port and
│ │ │ │ +detecting port failures, is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1798973693-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="1798973693-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1798973693-2">(</span><span class="p" data-group-id="1798973693-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1798973693-3">]</span><span class="p" data-group-id="1798973693-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1798973693-4">(</span><span class="p" data-group-id="1798973693-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1798973693-5">]</span><span class="p" data-group-id="1798973693-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1798973693-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="1798973693-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1798973693-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1798973693-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="1798973693-8">]</span><span class="p" data-group-id="1798973693-7">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="1798973693-9">(</span><span class="p" data-group-id="1798973693-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="9970460223-10">(</span><span class="n">X</span><span class="p" data-group-id="9970460223-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="9970460223-11">(</span><span class="p" data-group-id="9970460223-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="9970460223-12">}</span><span class="p" data-group-id="9970460223-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="9970460223-13">(</span><span class="n">Y</span><span class="p" data-group-id="9970460223-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="9970460223-14">(</span><span class="p" data-group-id="9970460223-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9970460223-15">}</span><span class="p" data-group-id="9970460223-14">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="1798973693-10">(</span><span class="n">X</span><span class="p" data-group-id="1798973693-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="1798973693-11">(</span><span class="p" data-group-id="1798973693-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1798973693-12">}</span><span class="p" data-group-id="1798973693-11">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="1798973693-13">(</span><span class="n">Y</span><span class="p" data-group-id="1798973693-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="1798973693-14">(</span><span class="p" data-group-id="1798973693-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1798973693-15">}</span><span class="p" data-group-id="1798973693-14">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="9970460223-16">(</span><span class="n">Msg</span><span class="p" data-group-id="9970460223-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9970460223-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="9970460223-18">(</span><span class="p" data-group-id="9970460223-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="9970460223-17">}</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="1798973693-16">(</span><span class="n">Msg</span><span class="p" data-group-id="1798973693-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1798973693-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1798973693-18">(</span><span class="p" data-group-id="1798973693-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1798973693-17">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="9970460223-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9970460223-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="1798973693-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="1798973693-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="9970460223-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="9970460223-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="9970460223-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="9970460223-22">(</span><span class="p" data-group-id="9970460223-22">)</span><span class="p" data-group-id="9970460223-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="9970460223-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="9970460223-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="9970460223-24">(</span><span class="p" data-group-id="9970460223-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="9970460223-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9970460223-26">[</span><span class="p" data-group-id="9970460223-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="9970460223-27">}</span><span class="p" data-group-id="9970460223-26">]</span><span class="p" data-group-id="9970460223-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="9970460223-28">(</span><span class="n">Port</span><span class="p" data-group-id="9970460223-28">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="1798973693-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="1798973693-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="1798973693-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1798973693-22">(</span><span class="p" data-group-id="1798973693-22">)</span><span class="p" data-group-id="1798973693-21">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="1798973693-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="1798973693-23">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="1798973693-24">(</span><span class="p" data-group-id="1798973693-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="1798973693-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1798973693-26">[</span><span class="p" data-group-id="1798973693-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="1798973693-27">}</span><span class="p" data-group-id="1798973693-26">]</span><span class="p" data-group-id="1798973693-24">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="1798973693-28">(</span><span class="n">Port</span><span class="p" data-group-id="1798973693-28">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="9970460223-29">(</span><span class="n">Port</span><span class="p" data-group-id="9970460223-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="1798973693-29">(</span><span class="n">Port</span><span class="p" data-group-id="1798973693-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="9970460223-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="9970460223-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9970460223-31">{</span><span class="nf">self</span><span class="p" data-group-id="9970460223-32">(</span><span class="p" data-group-id="9970460223-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9970460223-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="9970460223-34">(</span><span class="n">Msg</span><span class="p" data-group-id="9970460223-34">)</span><span class="p" data-group-id="9970460223-33">}</span><span class="p" data-group-id="9970460223-31">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="1798973693-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1798973693-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1798973693-31">{</span><span class="nf">self</span><span class="p" data-group-id="1798973693-32">(</span><span class="p" data-group-id="1798973693-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1798973693-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="1798973693-34">(</span><span class="n">Msg</span><span class="p" data-group-id="1798973693-34">)</span><span class="p" data-group-id="1798973693-33">}</span><span class="p" data-group-id="1798973693-31">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="9970460223-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9970460223-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9970460223-36">}</span><span class="p" data-group-id="9970460223-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9970460223-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="9970460223-38">(</span><span class="n">Data</span><span class="p" data-group-id="9970460223-38">)</span><span class="p" data-group-id="9970460223-37">}</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="1798973693-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1798973693-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1798973693-36">}</span><span class="p" data-group-id="1798973693-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1798973693-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="1798973693-38">(</span><span class="n">Data</span><span class="p" data-group-id="1798973693-38">)</span><span class="p" data-group-id="1798973693-37">}</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="9970460223-39">(</span><span class="n">Port</span><span class="p" data-group-id="9970460223-39">)</span><span class="p">;</span><span class="w">
│ │ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="1798973693-39">(</span><span class="n">Port</span><span class="p" data-group-id="1798973693-39">)</span><span class="p">;</span><span class="w">
│ │ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9970460223-40">{</span><span class="nf">self</span><span class="p" data-group-id="9970460223-41">(</span><span class="p" data-group-id="9970460223-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="9970460223-40">}</span><span class="p">,</span><span class="w">
│ │ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1798973693-40">{</span><span class="nf">self</span><span class="p" data-group-id="1798973693-41">(</span><span class="p" data-group-id="1798973693-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="1798973693-40">}</span><span class="p">,</span><span class="w">
│ │ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ │ -		</span><span class="p" data-group-id="9970460223-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="9970460223-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="9970460223-43">(</span><span class="ss">normal</span><span class="p" data-group-id="9970460223-43">)</span><span class="w">
│ │ │ │ +		</span><span class="p" data-group-id="1798973693-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="1798973693-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="1798973693-43">(</span><span class="ss">normal</span><span class="p" data-group-id="1798973693-43">)</span><span class="w">
│ │ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ │ -	</span><span class="p" data-group-id="9970460223-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="9970460223-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="9970460223-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="9970460223-45">)</span><span class="w">
│ │ │ │ +	</span><span class="p" data-group-id="1798973693-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="1798973693-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="1798973693-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="1798973693-45">)</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="9970460223-46">(</span><span class="p" data-group-id="9970460223-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="9970460223-47">}</span><span class="p" data-group-id="9970460223-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9970460223-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="9970460223-48">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="9970460223-49">(</span><span class="p" data-group-id="9970460223-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9970460223-50">}</span><span class="p" data-group-id="9970460223-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9970460223-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9970460223-51">]</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="1798973693-46">(</span><span class="p" data-group-id="1798973693-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1798973693-47">}</span><span class="p" data-group-id="1798973693-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1798973693-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1798973693-48">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="1798973693-49">(</span><span class="p" data-group-id="1798973693-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1798973693-50">}</span><span class="p" data-group-id="1798973693-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1798973693-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1798973693-51">]</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="9970460223-52">(</span><span class="p" data-group-id="9970460223-53">[</span><span class="n">Int</span><span class="p" data-group-id="9970460223-53">]</span><span class="p" data-group-id="9970460223-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-program" class="section-heading">
│ │ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="1798973693-52">(</span><span class="p" data-group-id="1798973693-53">[</span><span class="n">Int</span><span class="p" data-group-id="1798973693-53">]</span><span class="p" data-group-id="1798973693-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-program" class="section-heading">
│ │ │ │    <a href="#c-program" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">C Program</span>
│ │ │ │  </h2>
│ │ │ │  <p>On the C side, it is necessary to write functions for receiving and sending data
│ │ │ │  with 2 byte length indicators from/to Erlang. By default, the C program is to
│ │ │ │ @@ -238,22 +238,22 @@
│ │ │ │  and terminates.</p><h2 id="running-the-example" class="section-heading">
│ │ │ │    <a href="#running-the-example" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Running the Example</span>
│ │ │ │  </h2>
│ │ │ │  <p><em>Step 1.</em> Compile the C code:</p><pre><code class="text">$ gcc -o extprg complex.c erl_comm.c port.c</code></pre><p><em>Step 2.</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="sc">$ </span><span class="ss">erl</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="7376444995-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="7376444995-1">]</span><span class="w"> </span><span class="p" data-group-id="7376444995-2">[</span><span class="ss">source</span><span class="p" data-group-id="7376444995-2">]</span><span class="w"> </span><span class="p" data-group-id="7376444995-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="7376444995-3">]</span><span class="w"> </span><span class="p" data-group-id="7376444995-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="7376444995-4">]</span><span class="w"> </span><span class="p" data-group-id="7376444995-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="7376444995-5">]</span><span class="w"> </span><span class="p" data-group-id="7376444995-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="7376444995-6">]</span><span class="w"> </span><span class="p" data-group-id="7376444995-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="7376444995-7">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="9388577292-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="9388577292-1">]</span><span class="w"> </span><span class="p" data-group-id="9388577292-2">[</span><span class="ss">source</span><span class="p" data-group-id="9388577292-2">]</span><span class="w"> </span><span class="p" data-group-id="9388577292-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="9388577292-3">]</span><span class="w"> </span><span class="p" data-group-id="9388577292-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="9388577292-4">]</span><span class="w"> </span><span class="p" data-group-id="9388577292-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="9388577292-5">]</span><span class="w"> </span><span class="p" data-group-id="9388577292-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="9388577292-6">]</span><span class="w"> </span><span class="p" data-group-id="9388577292-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="9388577292-7">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="7376444995-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="7376444995-9">(</span><span class="p" data-group-id="7376444995-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="7376444995-8">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="7376444995-10">(</span><span class="ss">complex1</span><span class="p" data-group-id="7376444995-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7376444995-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex1</span><span class="p" data-group-id="7376444995-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2406445119-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="2406445119-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="9388577292-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="9388577292-9">(</span><span class="p" data-group-id="9388577292-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="9388577292-8">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="9388577292-10">(</span><span class="ss">complex1</span><span class="p" data-group-id="9388577292-10">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9388577292-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex1</span><span class="p" data-group-id="9388577292-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5178480217-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="5178480217-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="o">&lt;</span><span class="mf">0.34</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ │ -3&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="2406445119-2">(</span><span class="mi">3</span><span class="p" data-group-id="2406445119-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +3&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="5178480217-2">(</span><span class="mi">3</span><span class="p" data-group-id="5178480217-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="2406445119-3">(</span><span class="mi">5</span><span class="p" data-group-id="2406445119-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +4&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="5178480217-3">(</span><span class="mi">5</span><span class="p" data-group-id="5178480217-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ │ -5&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="2406445119-4">(</span><span class="p" data-group-id="2406445119-4">)</span><span class="p">.</span><span class="w">
│ │ │ │ +5&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="5178480217-4">(</span><span class="p" data-group-id="5178480217-4">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">stop</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/bit_syntax.xhtml
│ │ │ │ @@ -24,48 +24,48 @@
│ │ │ │    <a href="#introduction" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Introduction</span>
│ │ │ │  </h2>
│ │ │ │  <p>The complete specification for the bit syntax appears in the
│ │ │ │  <a href="../../../lib/../system/doc/html/expressions.xhtml#bit-syntax-expressions">Reference Manual</a>.</p><p>In Erlang, a Bin is used for constructing binaries and matching binary patterns.
│ │ │ │ -A Bin is written with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3268058385-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="3268058385-1">&gt;&gt;</span></code></pre><p>A Bin is a low-level sequence of bits or bytes. The purpose of a Bin is to
│ │ │ │ -enable construction of binaries:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4475856255-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="4475856255-1">&gt;&gt;</span></code></pre><p>All elements must be bound. Or match a binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8791648665-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="8791648665-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span></code></pre><p>Here, <code class="inline">Bin</code> is bound and the elements are bound or unbound, as in any match.</p><p>A Bin does not need to consist of a whole number of bytes.</p><p>A <em>bitstring</em> is a sequence of zero or more bits, where the number of bits does
│ │ │ │ +A Bin is written with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9958887898-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="9958887898-1">&gt;&gt;</span></code></pre><p>A Bin is a low-level sequence of bits or bytes. The purpose of a Bin is to
│ │ │ │ +enable construction of binaries:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2320752576-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="2320752576-1">&gt;&gt;</span></code></pre><p>All elements must be bound. Or match a binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7401963494-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="7401963494-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span></code></pre><p>Here, <code class="inline">Bin</code> is bound and the elements are bound or unbound, as in any match.</p><p>A Bin does not need to consist of a whole number of bytes.</p><p>A <em>bitstring</em> is a sequence of zero or more bits, where the number of bits does
│ │ │ │  not need to be divisible by 8. If the number of bits is divisible by 8, the
│ │ │ │  bitstring is also a binary.</p><p>Each element specifies a certain <em>segment</em> of the bitstring. A segment is a set
│ │ │ │  of contiguous bits of the binary (not necessarily on a byte boundary). The first
│ │ │ │  element specifies the initial segment, the second element specifies the
│ │ │ │  following segment, and so on.</p><p>The following examples illustrate how binaries are constructed, or matched, and
│ │ │ │  how elements and tails are specified.</p><h3 id="examples" class="section-heading">
│ │ │ │    <a href="#examples" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Examples</span>
│ │ │ │  </h3>
│ │ │ │  <p><em>Example 1:</em> A binary can be constructed from a set of constants or a string
│ │ │ │ -literal:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin11</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7997701952-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">17</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="7997701952-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Bin12</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7997701952-2">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7997701952-2">&gt;&gt;</span></code></pre><p>This gives two binaries of size 3, with the following evaluations:</p><ul><li><a href="../../../lib/../erts/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin11)</code></a> evaluates to <code class="inline">[1, 17, 42]</code>.</li><li><a href="../../../lib/../erts/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin12)</code></a> evaluates to <code class="inline">[97, 98, 99]</code>.</li></ul><p><em>Example 2:</em>Similarly, a binary can be constructed from a set of bound
│ │ │ │ +literal:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin11</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7421141801-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">17</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="7421141801-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Bin12</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7421141801-2">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7421141801-2">&gt;&gt;</span></code></pre><p>This gives two binaries of size 3, with the following evaluations:</p><ul><li><a href="../../../lib/../erts/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin11)</code></a> evaluates to <code class="inline">[1, 17, 42]</code>.</li><li><a href="../../../lib/../erts/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin12)</code></a> evaluates to <code class="inline">[97, 98, 99]</code>.</li></ul><p><em>Example 2:</em>Similarly, a binary can be constructed from a set of bound
│ │ │ │  variables:</p><pre><code class="makeup erlang" translate="no"><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">17</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9922890457-1">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9922890457-1">&gt;&gt;</span></code></pre><p>This gives a binary of size 4. Here, a <em>size expression</em> is used for the
│ │ │ │ +</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7044723168-1">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="7044723168-1">&gt;&gt;</span></code></pre><p>This gives a binary of size 4. Here, a <em>size expression</em> is used for the
│ │ │ │  variable <code class="inline">C</code> to specify a 16-bits segment of <code class="inline">Bin2</code>.</p><p><a href="../../../lib/../erts/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin2)</code></a> evaluates to <code class="inline">[1, 17, 00, 42]</code>.</p><p><em>Example 3:</em> A Bin can also be used for matching. <code class="inline">D</code>, <code class="inline">E</code>, and <code class="inline">F</code> are unbound
│ │ │ │ -variables, and <code class="inline">Bin2</code> is bound, as in Example 2:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0392286905-1">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0392286905-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin2</span></code></pre><p>This gives <code class="inline">D = 273</code>, <code class="inline">E = 00</code>, and F binds to a binary of size 1:
│ │ │ │ +variables, and <code class="inline">Bin2</code> is bound, as in Example 2:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3509309685-1">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3509309685-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin2</span></code></pre><p>This gives <code class="inline">D = 273</code>, <code class="inline">E = 00</code>, and F binds to a binary of size 1:
│ │ │ │  <code class="inline">binary_to_list(F) = [42]</code>.</p><p><em>Example 4:</em> The following is a more elaborate example of matching. Here,
│ │ │ │  <code class="inline">Dgram</code> is bound to the consecutive bytes of an IP datagram of IP protocol
│ │ │ │ -version 4. The ambition is to extract the header and the data of the datagram:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6787627117-1">(</span><span class="n">IP_VERSION</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="6787627117-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6787627117-2">(</span><span class="n">IP_MIN_HDR_LEN</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="6787627117-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +version 4. The ambition is to extract the header and the data of the datagram:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5208498648-1">(</span><span class="n">IP_VERSION</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="5208498648-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5208498648-2">(</span><span class="n">IP_MIN_HDR_LEN</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="5208498648-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">DgramSize</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="6787627117-3">(</span><span class="n">Dgram</span><span class="p" data-group-id="6787627117-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">DgramSize</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="5208498648-3">(</span><span class="n">Dgram</span><span class="p" data-group-id="5208498648-3">)</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="k">case</span><span class="w"> </span><span class="n">Dgram</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="6787627117-4">&lt;&lt;</span><span class="o">?</span><span class="n">IP_VERSION</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">HLen</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">SrvcType</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">TotLen</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5208498648-4">&lt;&lt;</span><span class="o">?</span><span class="n">IP_VERSION</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">HLen</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">SrvcType</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">TotLen</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w">
│ │ │ │        </span><span class="n">ID</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w"> </span><span class="n">Flgs</span><span class="p">:</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">FragOff</span><span class="p">:</span><span class="mi">13</span><span class="p">,</span><span class="w">
│ │ │ │        </span><span class="n">TTL</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">Proto</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">HdrChkSum</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w">
│ │ │ │        </span><span class="n">SrcIP</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="w">
│ │ │ │ -      </span><span class="n">DestIP</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="w"> </span><span class="n">RestDgram</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6787627117-4">&gt;&gt;</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">HLen</span><span class="o">&gt;=</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="n">HLen</span><span class="o">=&lt;</span><span class="n">DgramSize</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -        </span><span class="n">OptsLen</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="p" data-group-id="6787627117-5">(</span><span class="n">HLen</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">?</span><span class="n">IP_MIN_HDR_LEN</span><span class="p" data-group-id="6787627117-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="6787627117-6">&lt;&lt;</span><span class="n">Opts</span><span class="p">:</span><span class="n">OptsLen</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Data</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6787627117-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RestDgram</span><span class="p">,</span><span class="w">
│ │ │ │ +      </span><span class="n">DestIP</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="w"> </span><span class="n">RestDgram</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5208498648-4">&gt;&gt;</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">HLen</span><span class="o">&gt;=</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="n">HLen</span><span class="o">=&lt;</span><span class="n">DgramSize</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="n">OptsLen</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="p" data-group-id="5208498648-5">(</span><span class="n">HLen</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">?</span><span class="n">IP_MIN_HDR_LEN</span><span class="p" data-group-id="5208498648-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="5208498648-6">&lt;&lt;</span><span class="n">Opts</span><span class="p">:</span><span class="n">OptsLen</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Data</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5208498648-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RestDgram</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>Here, the segment corresponding to the <code class="inline">Opts</code> variable has a <em>type modifier</em>,
│ │ │ │  specifying that <code class="inline">Opts</code> is to bind to a binary. All other variables have the
│ │ │ │  default type equal to unsigned integer.</p><p>An IP datagram header is of variable length. This length is measured in the
│ │ │ │  number of 32-bit words and is given in the segment corresponding to <code class="inline">HLen</code>. The
│ │ │ │  minimum value of <code class="inline">HLen</code> is 5. It is the segment corresponding to <code class="inline">Opts</code> that is
│ │ │ │  variable, so if <code class="inline">HLen</code> is equal to 5, <code class="inline">Opts</code> becomes an empty binary.</p><p>The tail variables <code class="inline">RestDgram</code> and <code class="inline">Data</code> bind to binaries, as all tail
│ │ │ │ @@ -123,77 +123,77 @@
│ │ │ │  <p>This section describes the rules for constructing binaries using the bit syntax.
│ │ │ │  Unlike when constructing lists or tuples, the construction of a binary can fail
│ │ │ │  with a <code class="inline">badarg</code> exception.</p><p>There can be zero or more segments in a binary to be constructed. The expression
│ │ │ │  <code class="inline">&lt;&lt;&gt;&gt;</code> constructs a zero length binary.</p><p>Each segment in a binary can consist of zero or more bits. There are no
│ │ │ │  alignment rules for individual segments of type <code class="inline">integer</code> and <code class="inline">float</code>. For
│ │ │ │  binaries and bitstrings without size, the unit specifies the alignment. Since
│ │ │ │  the default alignment for the <code class="inline">binary</code> type is 8, the size of a binary segment
│ │ │ │ -must be a multiple of 8 bits, that is, only whole bytes.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0036250289-1">&lt;&lt;</span><span class="n">Bin</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Bitstring</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="0036250289-1">&gt;&gt;</span></code></pre><p>The variable <code class="inline">Bin</code> must contain a whole number of bytes, because the <code class="inline">binary</code>
│ │ │ │ +must be a multiple of 8 bits, that is, only whole bytes.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3290526510-1">&lt;&lt;</span><span class="n">Bin</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Bitstring</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3290526510-1">&gt;&gt;</span></code></pre><p>The variable <code class="inline">Bin</code> must contain a whole number of bytes, because the <code class="inline">binary</code>
│ │ │ │  type defaults to <code class="inline">unit:8</code>. A <code class="inline">badarg</code> exception is generated if <code class="inline">Bin</code> consist
│ │ │ │  of, for example, 17 bits.</p><p>The <code class="inline">Bitstring</code> variable can consist of any number of bits, for example, 0, 1,
│ │ │ │  8, 11, 17, 42, and so on. This is because the default <code class="inline">unit</code> for bitstrings
│ │ │ │  is 1.</p><p>For clarity, it is recommended not to change the unit size for binaries.
│ │ │ │  Instead, use <code class="inline">binary</code> when you need byte alignment and <code class="inline">bitstring</code> when you need
│ │ │ │  bit alignment.</p><p>The following example successfully constructs a bitstring of 7 bits, provided
│ │ │ │ -that all of X and Y are integers:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4180532281-1">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">6</span><span class="p" data-group-id="4180532281-1">&gt;&gt;</span></code></pre><p>As mentioned earlier, segments have the following general syntax:</p><p><code class="inline">Value:Size/TypeSpecifierList</code></p><p>When constructing binaries, <code class="inline">Value</code> and <code class="inline">Size</code> can be any Erlang expression.
│ │ │ │ +that all of X and Y are integers:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7663414082-1">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">6</span><span class="p" data-group-id="7663414082-1">&gt;&gt;</span></code></pre><p>As mentioned earlier, segments have the following general syntax:</p><p><code class="inline">Value:Size/TypeSpecifierList</code></p><p>When constructing binaries, <code class="inline">Value</code> and <code class="inline">Size</code> can be any Erlang expression.
│ │ │ │  However, for syntactical reasons, both <code class="inline">Value</code> and <code class="inline">Size</code> must be enclosed in
│ │ │ │  parenthesis if the expression consists of anything more than a single literal or
│ │ │ │ -a variable. The following gives a compiler syntax error:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0623092536-1">&lt;&lt;</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0623092536-1">&gt;&gt;</span></code></pre><p>This expression must be rewritten into the following, to be accepted by the
│ │ │ │ -compiler:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5143865567-1">&lt;&lt;</span><span class="p" data-group-id="5143865567-2">(</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="5143865567-2">)</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="5143865567-1">&gt;&gt;</span></code></pre><h3 id="including-literal-strings" class="section-heading">
│ │ │ │ +a variable. The following gives a compiler syntax error:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3561449844-1">&lt;&lt;</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3561449844-1">&gt;&gt;</span></code></pre><p>This expression must be rewritten into the following, to be accepted by the
│ │ │ │ +compiler:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7902764353-1">&lt;&lt;</span><span class="p" data-group-id="7902764353-2">(</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="7902764353-2">)</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="7902764353-1">&gt;&gt;</span></code></pre><h3 id="including-literal-strings" class="section-heading">
│ │ │ │    <a href="#including-literal-strings" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Including Literal Strings</span>
│ │ │ │  </h3>
│ │ │ │ -<p>A literal string can be written instead of an element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4689014518-1">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="4689014518-1">&gt;&gt;</span></code></pre><p>This is syntactic sugar for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9368191721-1">&lt;&lt;</span><span class="sc">$h</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$o</span><span class="p" data-group-id="9368191721-1">&gt;&gt;</span></code></pre><h2 id="matching-binaries" class="section-heading">
│ │ │ │ +<p>A literal string can be written instead of an element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3465976830-1">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="3465976830-1">&gt;&gt;</span></code></pre><p>This is syntactic sugar for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4767497461-1">&lt;&lt;</span><span class="sc">$h</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$o</span><span class="p" data-group-id="4767497461-1">&gt;&gt;</span></code></pre><h2 id="matching-binaries" class="section-heading">
│ │ │ │    <a href="#matching-binaries" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Matching Binaries</span>
│ │ │ │  </h2>
│ │ │ │  <p>This section describes the rules for matching binaries, using the bit syntax.</p><p>There can be zero or more segments in a binary pattern. A binary pattern can
│ │ │ │  occur wherever patterns are allowed, including inside other patterns. Binary
│ │ │ │  patterns cannot be nested. The pattern <code class="inline">&lt;&lt;&gt;&gt;</code> matches a zero length binary.</p><p>Each segment in a binary can consist of zero or more bits. A segment of type
│ │ │ │  <code class="inline">binary</code> must have a size evenly divisible by 8 (or divisible by the unit size,
│ │ │ │  if the unit size has been changed). A segment of type <code class="inline">bitstring</code> has no
│ │ │ │  restrictions on the size. A segment of type <code class="inline">float</code> must have size 64 or 32.</p><p>As mentioned earlier, segments have the following general syntax:</p><p><code class="inline">Value:Size/TypeSpecifierList</code></p><p>When matching <code class="inline">Value</code>, value must be either a variable or an integer, or a
│ │ │ │  floating point literal. Expressions are not allowed.</p><p><code class="inline">Size</code> must be a
│ │ │ │  <a href="../../../lib/../system/doc/html/expressions.xhtml#guard-expressions">guard expression</a>, which can use
│ │ │ │ -literals and previously bound variables. The following is not allowed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="1065456410-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1065456410-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="1065456410-2">&gt;&gt;</span><span class="p" data-group-id="1065456410-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="1065456410-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="1065456410-3">}</span><span class="p">.</span></code></pre><p>The two occurrences of <code class="inline">N</code> are not related. The compiler will complain that the
│ │ │ │ -<code class="inline">N</code> in the size field is unbound.</p><p>The correct way to write this example is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="9892695006-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="9892695006-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="9892695006-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9892695006-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="9892695006-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="9892695006-3">}</span><span class="p">.</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Before OTP 23, <code class="inline">Size</code> was restricted to be an integer or a variable bound to
│ │ │ │ +literals and previously bound variables. The following is not allowed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="3869001831-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3869001831-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3869001831-2">&gt;&gt;</span><span class="p" data-group-id="3869001831-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="3869001831-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="3869001831-3">}</span><span class="p">.</span></code></pre><p>The two occurrences of <code class="inline">N</code> are not related. The compiler will complain that the
│ │ │ │ +<code class="inline">N</code> in the size field is unbound.</p><p>The correct way to write this example is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="5615509347-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="5615509347-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="5615509347-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5615509347-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="5615509347-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="5615509347-3">}</span><span class="p">.</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Before OTP 23, <code class="inline">Size</code> was restricted to be an integer or a variable bound to
│ │ │ │  an integer.</p></section><h3 id="binding-and-using-a-size-variable" class="section-heading">
│ │ │ │    <a href="#binding-and-using-a-size-variable" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Binding and Using a Size Variable</span>
│ │ │ │  </h3>
│ │ │ │  <p>There is one exception to the rule that a variable that is used as size must be
│ │ │ │  previously bound. It is possible to match and bind a variable, and use it as a
│ │ │ │ -size within the same binary pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="6809504300-1">(</span><span class="p" data-group-id="6809504300-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="n">Sz</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6809504300-2">&gt;&gt;</span><span class="p" data-group-id="6809504300-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="6809504300-3">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="6809504300-3">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is bound to the value in the first byte of the binary. <code class="inline">Sz</code> is then
│ │ │ │ -used at the number of bytes to match out as a binary.</p><p>Starting in OTP 23, the size can be a guard expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="5126784086-1">(</span><span class="p" data-group-id="5126784086-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="p" data-group-id="5126784086-3">(</span><span class="p" data-group-id="5126784086-4">(</span><span class="n">Sz</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="5126784086-4">)</span><span class="o">*</span><span class="mi">8</span><span class="p" data-group-id="5126784086-3">)</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5126784086-2">&gt;&gt;</span><span class="p" data-group-id="5126784086-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="5126784086-5">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="5126784086-5">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is the combined size of the header and the payload, so we will need to
│ │ │ │ +size within the same binary pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="1129084540-1">(</span><span class="p" data-group-id="1129084540-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="n">Sz</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="1129084540-2">&gt;&gt;</span><span class="p" data-group-id="1129084540-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="1129084540-3">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="1129084540-3">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is bound to the value in the first byte of the binary. <code class="inline">Sz</code> is then
│ │ │ │ +used at the number of bytes to match out as a binary.</p><p>Starting in OTP 23, the size can be a guard expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="4360293088-1">(</span><span class="p" data-group-id="4360293088-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="p" data-group-id="4360293088-3">(</span><span class="p" data-group-id="4360293088-4">(</span><span class="n">Sz</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="4360293088-4">)</span><span class="o">*</span><span class="mi">8</span><span class="p" data-group-id="4360293088-3">)</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4360293088-2">&gt;&gt;</span><span class="p" data-group-id="4360293088-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="4360293088-5">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="4360293088-5">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is the combined size of the header and the payload, so we will need to
│ │ │ │  subtract one byte to get the size of the payload.</p><h3 id="getting-the-rest-of-the-binary-or-bitstring" class="section-heading">
│ │ │ │    <a href="#getting-the-rest-of-the-binary-or-bitstring" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Getting the Rest of the Binary or Bitstring</span>
│ │ │ │  </h3>
│ │ │ │ -<p>To match out the rest of a binary, specify a binary field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="3320482508-1">(</span><span class="p" data-group-id="3320482508-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3320482508-2">&gt;&gt;</span><span class="p" data-group-id="3320482508-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>The size of the tail must be evenly divisible by 8.</p><p>To match out the rest of a bitstring, specify a field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="1800298476-1">(</span><span class="p" data-group-id="1800298476-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="1800298476-2">&gt;&gt;</span><span class="p" data-group-id="1800298476-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>There are no restrictions on the number of bits in the tail.</p><h2 id="appending-to-a-binary" class="section-heading">
│ │ │ │ +<p>To match out the rest of a binary, specify a binary field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="7110707053-1">(</span><span class="p" data-group-id="7110707053-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7110707053-2">&gt;&gt;</span><span class="p" data-group-id="7110707053-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>The size of the tail must be evenly divisible by 8.</p><p>To match out the rest of a bitstring, specify a field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="3546323393-1">(</span><span class="p" data-group-id="3546323393-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3546323393-2">&gt;&gt;</span><span class="p" data-group-id="3546323393-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>There are no restrictions on the number of bits in the tail.</p><h2 id="appending-to-a-binary" class="section-heading">
│ │ │ │    <a href="#appending-to-a-binary" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Appending to a Binary</span>
│ │ │ │  </h2>
│ │ │ │ -<p>Appending to a binary in an efficient way can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">triples_to_bin</span><span class="p" data-group-id="2328729403-1">(</span><span class="n">T</span><span class="p" data-group-id="2328729403-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="2328729403-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2328729403-3">&lt;&lt;</span><span class="p" data-group-id="2328729403-3">&gt;&gt;</span><span class="p" data-group-id="2328729403-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>Appending to a binary in an efficient way can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">triples_to_bin</span><span class="p" data-group-id="9727795018-1">(</span><span class="n">T</span><span class="p" data-group-id="9727795018-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="9727795018-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9727795018-3">&lt;&lt;</span><span class="p" data-group-id="9727795018-3">&gt;&gt;</span><span class="p" data-group-id="9727795018-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="2328729403-4">(</span><span class="p" data-group-id="2328729403-5">[</span><span class="p" data-group-id="2328729403-6">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p" data-group-id="2328729403-6">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="2328729403-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="2328729403-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="2328729403-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2328729403-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">X</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Z</span><span class="p">:</span><span class="mi">32</span><span class="p" data-group-id="2328729403-8">&gt;&gt;</span><span class="p" data-group-id="2328729403-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="2328729403-9">(</span><span class="p" data-group-id="2328729403-10">[</span><span class="p" data-group-id="2328729403-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="2328729403-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="9727795018-4">(</span><span class="p" data-group-id="9727795018-5">[</span><span class="p" data-group-id="9727795018-6">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p" data-group-id="9727795018-6">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9727795018-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="9727795018-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="9727795018-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9727795018-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">X</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Z</span><span class="p">:</span><span class="mi">32</span><span class="p" data-group-id="9727795018-8">&gt;&gt;</span><span class="p" data-group-id="9727795018-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="9727795018-9">(</span><span class="p" data-group-id="9727795018-10">[</span><span class="p" data-group-id="9727795018-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="9727795018-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/binaryhandling.xhtml
│ │ │ │ @@ -19,43 +19,43 @@
│ │ │ │  
│ │ │ │      <h1 id="content">
│ │ │ │  Constructing and Matching Binaries
│ │ │ │      </h1>
│ │ │ │  <p>This section gives a few examples on how to handle binaries in an efficient way.
│ │ │ │  The sections that follow take an in-depth look at how binaries are implemented
│ │ │ │  and how to best take advantages of the optimizations done by the compiler and
│ │ │ │ -runtime system.</p><p>Binaries can be efficiently <em>built</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_list_to_binary</span><span class="p" data-group-id="9779763568-1">(</span><span class="n">List</span><span class="p" data-group-id="9779763568-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="9779763568-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779763568-3">&lt;&lt;</span><span class="p" data-group-id="9779763568-3">&gt;&gt;</span><span class="p" data-group-id="9779763568-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +runtime system.</p><p>Binaries can be efficiently <em>built</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_list_to_binary</span><span class="p" data-group-id="3094326452-1">(</span><span class="n">List</span><span class="p" data-group-id="3094326452-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="3094326452-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3094326452-3">&lt;&lt;</span><span class="p" data-group-id="3094326452-3">&gt;&gt;</span><span class="p" data-group-id="3094326452-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="9779763568-4">(</span><span class="p" data-group-id="9779763568-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9779763568-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="9779763568-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="9779763568-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779763568-7">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="9779763568-7">&gt;&gt;</span><span class="p" data-group-id="9779763568-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="9779763568-8">(</span><span class="p" data-group-id="9779763568-9">[</span><span class="p" data-group-id="9779763568-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="9779763568-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="3094326452-4">(</span><span class="p" data-group-id="3094326452-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3094326452-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3094326452-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="3094326452-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3094326452-7">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="3094326452-7">&gt;&gt;</span><span class="p" data-group-id="3094326452-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="3094326452-8">(</span><span class="p" data-group-id="3094326452-9">[</span><span class="p" data-group-id="3094326452-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3094326452-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Appending data to a binary as in the example is efficient because it is
│ │ │ │  specially optimized by the runtime system to avoid copying the <code class="inline">Acc</code> binary
│ │ │ │ -every time.</p><p>Prepending data to a binary in a loop is not efficient:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="8485332454-1">(</span><span class="n">List</span><span class="p" data-group-id="8485332454-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="8485332454-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8485332454-3">&lt;&lt;</span><span class="p" data-group-id="8485332454-3">&gt;&gt;</span><span class="p" data-group-id="8485332454-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +every time.</p><p>Prepending data to a binary in a loop is not efficient:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3440181541-1">(</span><span class="n">List</span><span class="p" data-group-id="3440181541-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3440181541-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3440181541-3">&lt;&lt;</span><span class="p" data-group-id="3440181541-3">&gt;&gt;</span><span class="p" data-group-id="3440181541-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="8485332454-4">(</span><span class="p" data-group-id="8485332454-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8485332454-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8485332454-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="8485332454-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8485332454-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="8485332454-7">&gt;&gt;</span><span class="p" data-group-id="8485332454-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="8485332454-8">(</span><span class="p" data-group-id="8485332454-9">[</span><span class="p" data-group-id="8485332454-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8485332454-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3440181541-4">(</span><span class="p" data-group-id="3440181541-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3440181541-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3440181541-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3440181541-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3440181541-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3440181541-7">&gt;&gt;</span><span class="p" data-group-id="3440181541-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3440181541-8">(</span><span class="p" data-group-id="3440181541-9">[</span><span class="p" data-group-id="3440181541-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3440181541-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>This is not efficient for long lists because the <code class="inline">Acc</code> binary is copied every
│ │ │ │ -time. One way to make the function more efficient is like this:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7587422629-1">(</span><span class="n">List</span><span class="p" data-group-id="7587422629-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7587422629-2">(</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="7587422629-3">(</span><span class="n">List</span><span class="p" data-group-id="7587422629-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7587422629-4">&lt;&lt;</span><span class="p" data-group-id="7587422629-4">&gt;&gt;</span><span class="p" data-group-id="7587422629-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +time. One way to make the function more efficient is like this:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0463936343-1">(</span><span class="n">List</span><span class="p" data-group-id="0463936343-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0463936343-2">(</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="0463936343-3">(</span><span class="n">List</span><span class="p" data-group-id="0463936343-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0463936343-4">&lt;&lt;</span><span class="p" data-group-id="0463936343-4">&gt;&gt;</span><span class="p" data-group-id="0463936343-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7587422629-5">(</span><span class="p" data-group-id="7587422629-6">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7587422629-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7587422629-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7587422629-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7587422629-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="7587422629-8">&gt;&gt;</span><span class="p" data-group-id="7587422629-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7587422629-9">(</span><span class="p" data-group-id="7587422629-10">[</span><span class="p" data-group-id="7587422629-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7587422629-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Another way to avoid copying the binary each time is like this:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0424573384-1">(</span><span class="p" data-group-id="0424573384-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0424573384-2">]</span><span class="p" data-group-id="0424573384-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="n">RevTail</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0424573384-3">(</span><span class="n">T</span><span class="p" data-group-id="0424573384-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0424573384-4">&lt;&lt;</span><span class="n">RevTail</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="0424573384-4">&gt;&gt;</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0424573384-5">(</span><span class="p" data-group-id="0424573384-6">[</span><span class="p" data-group-id="0424573384-6">]</span><span class="p" data-group-id="0424573384-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="0424573384-7">&lt;&lt;</span><span class="p" data-group-id="0424573384-7">&gt;&gt;</span><span class="p">.</span></code></pre><p>Note that in each of the <strong>DO</strong> examples, the binary to be appended to is always
│ │ │ │ -given as the first segment.</p><p>Binaries can be efficiently <em>matched</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="2202687733-1">(</span><span class="p" data-group-id="2202687733-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2202687733-2">&gt;&gt;</span><span class="p" data-group-id="2202687733-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2202687733-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="2202687733-4">(</span><span class="n">T</span><span class="p" data-group-id="2202687733-4">)</span><span class="p" data-group-id="2202687733-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="2202687733-5">(</span><span class="p" data-group-id="2202687733-6">&lt;&lt;</span><span class="p" data-group-id="2202687733-6">&gt;&gt;</span><span class="p" data-group-id="2202687733-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2202687733-7">[</span><span class="p" data-group-id="2202687733-7">]</span><span class="p">.</span></code></pre><h2 id="how-binaries-are-implemented" class="section-heading">
│ │ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0463936343-5">(</span><span class="p" data-group-id="0463936343-6">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0463936343-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="0463936343-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0463936343-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0463936343-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="0463936343-8">&gt;&gt;</span><span class="p" data-group-id="0463936343-7">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0463936343-9">(</span><span class="p" data-group-id="0463936343-10">[</span><span class="p" data-group-id="0463936343-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="0463936343-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Another way to avoid copying the binary each time is like this:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3385568531-1">(</span><span class="p" data-group-id="3385568531-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3385568531-2">]</span><span class="p" data-group-id="3385568531-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="n">RevTail</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3385568531-3">(</span><span class="n">T</span><span class="p" data-group-id="3385568531-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3385568531-4">&lt;&lt;</span><span class="n">RevTail</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="3385568531-4">&gt;&gt;</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="3385568531-5">(</span><span class="p" data-group-id="3385568531-6">[</span><span class="p" data-group-id="3385568531-6">]</span><span class="p" data-group-id="3385568531-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3385568531-7">&lt;&lt;</span><span class="p" data-group-id="3385568531-7">&gt;&gt;</span><span class="p">.</span></code></pre><p>Note that in each of the <strong>DO</strong> examples, the binary to be appended to is always
│ │ │ │ +given as the first segment.</p><p>Binaries can be efficiently <em>matched</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="9951324421-1">(</span><span class="p" data-group-id="9951324421-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9951324421-2">&gt;&gt;</span><span class="p" data-group-id="9951324421-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="9951324421-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="9951324421-4">(</span><span class="n">T</span><span class="p" data-group-id="9951324421-4">)</span><span class="p" data-group-id="9951324421-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="9951324421-5">(</span><span class="p" data-group-id="9951324421-6">&lt;&lt;</span><span class="p" data-group-id="9951324421-6">&gt;&gt;</span><span class="p" data-group-id="9951324421-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9951324421-7">[</span><span class="p" data-group-id="9951324421-7">]</span><span class="p">.</span></code></pre><h2 id="how-binaries-are-implemented" class="section-heading">
│ │ │ │    <a href="#how-binaries-are-implemented" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">How Binaries are Implemented</span>
│ │ │ │  </h2>
│ │ │ │  <p>Internally, binaries and bitstrings are implemented in the same way. In this
│ │ │ │  section, they are called <em>binaries</em> because that is what they are called in the
│ │ │ │ @@ -110,29 +110,29 @@
│ │ │ │  called referential transparency) of Erlang would break.</p><h2 id="constructing-binaries" class="section-heading">
│ │ │ │    <a href="#constructing-binaries" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Constructing Binaries</span>
│ │ │ │  </h2>
│ │ │ │  <p>Appending to a binary or bitstring in the following way is specially optimized
│ │ │ │ -to avoid copying the binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3163509432-1">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3163509432-1">&gt;&gt;</span><span class="w">
│ │ │ │ +to avoid copying the binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4902380314-1">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4902380314-1">&gt;&gt;</span><span class="w">
│ │ │ │  </span><span class="c1">%% - OR -</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3163509432-2">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">bitstring</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3163509432-2">&gt;&gt;</span></code></pre><p>This optimization is applied by the runtime system in a way that makes it
│ │ │ │ +</span><span class="p" data-group-id="4902380314-2">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">bitstring</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4902380314-2">&gt;&gt;</span></code></pre><p>This optimization is applied by the runtime system in a way that makes it
│ │ │ │  effective in most circumstances (for exceptions, see
│ │ │ │  <a href="binaryhandling.xhtml#forced_copying">Circumstances That Force Copying</a>). The
│ │ │ │  optimization in its basic form does not need any help from the compiler.
│ │ │ │  However, the compiler add hints to the runtime system when it is safe to apply
│ │ │ │  the optimization in a more efficient way.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>The compiler support for making the optimization more efficient was added in
│ │ │ │  Erlang/OTP 26.</p></section><p>To explain how the basic optimization works, let us examine the following code
│ │ │ │ -line by line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7111517487-1">&lt;&lt;</span><span class="mi">0</span><span class="p" data-group-id="7111517487-1">&gt;&gt;</span><span class="p">,</span><span class="w">                    </span><span class="c1">%% 1</span><span class="w">
│ │ │ │ -</span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7111517487-2">&lt;&lt;</span><span class="n">Bin0</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7111517487-2">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 2</span><span class="w">
│ │ │ │ -</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7111517487-3">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7111517487-3">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 3</span><span class="w">
│ │ │ │ -</span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7111517487-4">&lt;&lt;</span><span class="n">Bin2</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p" data-group-id="7111517487-4">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 4</span><span class="w">
│ │ │ │ -</span><span class="n">Bin4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7111517487-5">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="7111517487-5">&gt;&gt;</span><span class="p">,</span><span class="w">       </span><span class="c1">%% 5 !!!</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7111517487-6">{</span><span class="n">Bin4</span><span class="p">,</span><span class="n">Bin3</span><span class="p" data-group-id="7111517487-6">}</span><span class="w">                      </span><span class="c1">%% 6</span></code></pre><ul><li><p>Line 1 (marked with the <code class="inline">%% 1</code> comment), assigns a
│ │ │ │ +line by line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3087448816-1">&lt;&lt;</span><span class="mi">0</span><span class="p" data-group-id="3087448816-1">&gt;&gt;</span><span class="p">,</span><span class="w">                    </span><span class="c1">%% 1</span><span class="w">
│ │ │ │ +</span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3087448816-2">&lt;&lt;</span><span class="n">Bin0</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3087448816-2">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 2</span><span class="w">
│ │ │ │ +</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3087448816-3">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3087448816-3">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 3</span><span class="w">
│ │ │ │ +</span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3087448816-4">&lt;&lt;</span><span class="n">Bin2</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p" data-group-id="3087448816-4">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 4</span><span class="w">
│ │ │ │ +</span><span class="n">Bin4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3087448816-5">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="3087448816-5">&gt;&gt;</span><span class="p">,</span><span class="w">       </span><span class="c1">%% 5 !!!</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="3087448816-6">{</span><span class="n">Bin4</span><span class="p">,</span><span class="n">Bin3</span><span class="p" data-group-id="3087448816-6">}</span><span class="w">                      </span><span class="c1">%% 6</span></code></pre><ul><li><p>Line 1 (marked with the <code class="inline">%% 1</code> comment), assigns a
│ │ │ │  <a href="binaryhandling.xhtml#heap_binary">heap binary</a> to the <code class="inline">Bin0</code> variable.</p></li><li><p>Line 2 is an append operation. As <code class="inline">Bin0</code> has not been involved in an append
│ │ │ │  operation, a new <a href="binaryhandling.xhtml#refc_binary">refc binary</a> is created and
│ │ │ │  the contents of <code class="inline">Bin0</code> is copied into it. The <em>ProcBin</em> part of the refc
│ │ │ │  binary has its size set to the size of the data stored in the binary, while
│ │ │ │  the binary object has extra space allocated. The size of the binary object is
│ │ │ │  either twice the size of <code class="inline">Bin1</code> or 256, whichever is larger. In this case it
│ │ │ │  is 256.</p></li><li><p>Line 3 is more interesting. <code class="inline">Bin1</code> <em>has</em> been used in an append operation, and
│ │ │ │ @@ -158,23 +158,23 @@
│ │ │ │  handle an append operation to a heap binary by copying it to a refc binary (line
│ │ │ │  2), and also handle an append operation to a previous version of the binary by
│ │ │ │  copying it (line 5). The support for doing that does not come for free. For
│ │ │ │  example, to make it possible to know when it is necessary to copy the binary,
│ │ │ │  for every append operation, the runtime system must create a sub binary.</p><p>When the compiler can determine that none of those situations need to be handled
│ │ │ │  and that the append operation cannot possibly fail, the compiler generates code
│ │ │ │  that causes the runtime system to apply a more efficient variant of the
│ │ │ │ -optimization.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9843887449-1">(</span><span class="ss">repack</span><span class="p" data-group-id="9843887449-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9843887449-2">(</span><span class="p" data-group-id="9843887449-3">[</span><span class="ss">repack</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9843887449-3">]</span><span class="p" data-group-id="9843887449-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +optimization.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5903448851-1">(</span><span class="ss">repack</span><span class="p" data-group-id="5903448851-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5903448851-2">(</span><span class="p" data-group-id="5903448851-3">[</span><span class="ss">repack</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5903448851-3">]</span><span class="p" data-group-id="5903448851-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">repack</span><span class="p" data-group-id="9843887449-4">(</span><span class="n">Bin</span><span class="p" data-group-id="9843887449-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_binary</span><span class="p" data-group-id="9843887449-5">(</span><span class="n">Bin</span><span class="p" data-group-id="9843887449-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">repack</span><span class="p" data-group-id="9843887449-6">(</span><span class="n">Bin</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9843887449-7">&lt;&lt;</span><span class="p" data-group-id="9843887449-7">&gt;&gt;</span><span class="p" data-group-id="9843887449-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">repack</span><span class="p" data-group-id="5903448851-4">(</span><span class="n">Bin</span><span class="p" data-group-id="5903448851-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_binary</span><span class="p" data-group-id="5903448851-5">(</span><span class="n">Bin</span><span class="p" data-group-id="5903448851-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">repack</span><span class="p" data-group-id="5903448851-6">(</span><span class="n">Bin</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5903448851-7">&lt;&lt;</span><span class="p" data-group-id="5903448851-7">&gt;&gt;</span><span class="p" data-group-id="5903448851-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">repack</span><span class="p" data-group-id="9843887449-8">(</span><span class="p" data-group-id="9843887449-9">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9843887449-9">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9843887449-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">repack</span><span class="p" data-group-id="9843887449-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9843887449-11">&lt;&lt;</span><span class="n">Result</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9843887449-11">&gt;&gt;</span><span class="p" data-group-id="9843887449-10">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">repack</span><span class="p" data-group-id="9843887449-12">(</span><span class="p" data-group-id="9843887449-13">&lt;&lt;</span><span class="p" data-group-id="9843887449-13">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9843887449-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">repack</span><span class="p" data-group-id="5903448851-8">(</span><span class="p" data-group-id="5903448851-9">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5903448851-9">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="5903448851-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">repack</span><span class="p" data-group-id="5903448851-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5903448851-11">&lt;&lt;</span><span class="n">Result</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="5903448851-11">&gt;&gt;</span><span class="p" data-group-id="5903448851-10">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">repack</span><span class="p" data-group-id="5903448851-12">(</span><span class="p" data-group-id="5903448851-13">&lt;&lt;</span><span class="p" data-group-id="5903448851-13">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="5903448851-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">Result</span><span class="p">.</span></code></pre><p>The <code class="inline">repack/2</code> function only keeps a single version of the binary, so there is
│ │ │ │  never any need to copy the binary. The compiler rewrites the creation of the
│ │ │ │  empty binary in <code class="inline">repack/1</code> to instead create a refc binary with 256 bytes
│ │ │ │  already reserved; thus, the append operation in <code class="inline">repack/2</code> never needs to handle
│ │ │ │  a binary not prepared for appending.</p><p><a href="" id="forced_copying"></a></p><h3 id="circumstances-that-force-copying" class="section-heading">
│ │ │ │    <a href="#circumstances-that-force-copying" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │ @@ -186,72 +186,72 @@
│ │ │ │  reason is that the binary object can be moved (reallocated) during an append
│ │ │ │  operation, and when that happens, the pointer in the ProcBin must be updated. If
│ │ │ │  there would be more than one ProcBin pointing to the binary object, it would not
│ │ │ │  be possible to find and update all of them.</p><p>Therefore, certain operations on a binary mark it so that any future append
│ │ │ │  operation will be forced to copy the binary. In most cases, the binary object
│ │ │ │  will be shrunk at the same time to reclaim the extra space allocated for
│ │ │ │  growing.</p><p>When appending to a binary as follows, only the binary returned from the latest
│ │ │ │ -append operation will support further cheap append operations:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0299892156-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0299892156-1">&gt;&gt;</span></code></pre><p>In the code fragment in the beginning of this section, appending to <code class="inline">Bin</code> will
│ │ │ │ +append operation will support further cheap append operations:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5417885649-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5417885649-1">&gt;&gt;</span></code></pre><p>In the code fragment in the beginning of this section, appending to <code class="inline">Bin</code> will
│ │ │ │  be cheap, while appending to <code class="inline">Bin0</code> will force the creation of a new binary and
│ │ │ │  copying of the contents of <code class="inline">Bin0</code>.</p><p>If a binary is sent as a message to a process or port, the binary will be shrunk
│ │ │ │  and any further append operation will copy the binary data into a new binary.
│ │ │ │  For example, in the following code fragment <code class="inline">Bin1</code> will be copied in the third
│ │ │ │ -line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5851661131-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5851661131-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ +line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591678842-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9591678842-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ │  </span><span class="n">PortOrPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Bin1</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5851661131-2">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5851661131-2">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The same happens if you insert a binary into an Ets table, send it to a port
│ │ │ │ +</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9591678842-2">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9591678842-2">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The same happens if you insert a binary into an Ets table, send it to a port
│ │ │ │  using <a href="../../../lib/../erts/doc/html/erlang.html#port_command/2"><code class="inline">erlang:port_command/2</code></a>, or pass it to
│ │ │ │  <a href="../../../lib/../erts/doc/html/erl_nif.xhtml#enif_inspect_binary">enif_inspect_binary</a> in a NIF.</p><p>Matching a binary will also cause it to shrink and the next append operation
│ │ │ │ -will copy the binary data:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6440347725-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6440347725-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6440347725-2">&lt;&lt;</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6440347725-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin1</span><span class="p">,</span><span class="w">
│ │ │ │ -</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6440347725-3">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6440347725-3">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The reason is that a <a href="binaryhandling.xhtml#match_context">match context</a> contains a
│ │ │ │ +will copy the binary data:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6438496862-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6438496862-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6438496862-2">&lt;&lt;</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6438496862-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin1</span><span class="p">,</span><span class="w">
│ │ │ │ +</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6438496862-3">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6438496862-3">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The reason is that a <a href="binaryhandling.xhtml#match_context">match context</a> contains a
│ │ │ │  direct pointer to the binary data.</p><p>If a process simply keeps binaries (either in &quot;loop data&quot; or in the process
│ │ │ │  dictionary), the garbage collector can eventually shrink the binaries. If only
│ │ │ │  one such binary is kept, it will not be shrunk. If the process later appends to
│ │ │ │  a binary that has been shrunk, the binary object will be reallocated to make
│ │ │ │  place for the data to be appended.</p><h2 id="matching-binaries" class="section-heading">
│ │ │ │    <a href="#matching-binaries" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Matching Binaries</span>
│ │ │ │  </h2>
│ │ │ │ -<p>Let us revisit the example in the beginning of the previous section:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="1427002958-1">(</span><span class="p" data-group-id="1427002958-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="1427002958-2">&gt;&gt;</span><span class="p" data-group-id="1427002958-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1427002958-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="1427002958-4">(</span><span class="n">T</span><span class="p" data-group-id="1427002958-4">)</span><span class="p" data-group-id="1427002958-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="1427002958-5">(</span><span class="p" data-group-id="1427002958-6">&lt;&lt;</span><span class="p" data-group-id="1427002958-6">&gt;&gt;</span><span class="p" data-group-id="1427002958-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1427002958-7">[</span><span class="p" data-group-id="1427002958-7">]</span><span class="p">.</span></code></pre><p>The first time <code class="inline">my_binary_to_list/1</code> is called, a
│ │ │ │ +<p>Let us revisit the example in the beginning of the previous section:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="6074440889-1">(</span><span class="p" data-group-id="6074440889-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6074440889-2">&gt;&gt;</span><span class="p" data-group-id="6074440889-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="6074440889-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="6074440889-4">(</span><span class="n">T</span><span class="p" data-group-id="6074440889-4">)</span><span class="p" data-group-id="6074440889-3">]</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="6074440889-5">(</span><span class="p" data-group-id="6074440889-6">&lt;&lt;</span><span class="p" data-group-id="6074440889-6">&gt;&gt;</span><span class="p" data-group-id="6074440889-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6074440889-7">[</span><span class="p" data-group-id="6074440889-7">]</span><span class="p">.</span></code></pre><p>The first time <code class="inline">my_binary_to_list/1</code> is called, a
│ │ │ │  <a href="binaryhandling.xhtml#match_context">match context</a> is created. The match context
│ │ │ │  points to the first byte of the binary. 1 byte is matched out and the match
│ │ │ │  context is updated to point to the second byte in the binary.</p><p>At this point it would make sense to create a
│ │ │ │  <a href="binaryhandling.xhtml#sub_binary">sub binary</a>, but in this particular example the
│ │ │ │  compiler sees that there will soon be a call to a function (in this case, to
│ │ │ │  <code class="inline">my_binary_to_list/1</code> itself) that immediately will create a new match context
│ │ │ │  and discard the sub binary.</p><p>Therefore <code class="inline">my_binary_to_list/1</code> calls itself with the match context instead of
│ │ │ │  with a sub binary. The instruction that initializes the matching operation
│ │ │ │  basically does nothing when it sees that it was passed a match context instead
│ │ │ │  of a binary.</p><p>When the end of the binary is reached and the second clause matches, the match
│ │ │ │  context will simply be discarded (removed in the next garbage collection, as
│ │ │ │  there is no longer any reference to it).</p><p>To summarize, <code class="inline">my_binary_to_list/1</code> only needs to create <em>one</em> match context and
│ │ │ │  no sub binaries.</p><p>Notice that the match context in <code class="inline">my_binary_to_list/1</code> was discarded when the
│ │ │ │  entire binary had been traversed. What happens if the iteration stops before it
│ │ │ │ -has reached the end of the binary? Will the optimization still work?</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="2290492515-1">(</span><span class="p" data-group-id="2290492515-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2290492515-2">&gt;&gt;</span><span class="p" data-group-id="2290492515-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +has reached the end of the binary? Will the optimization still work?</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="5314813250-1">(</span><span class="p" data-group-id="5314813250-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5314813250-2">&gt;&gt;</span><span class="p" data-group-id="5314813250-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">T</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="2290492515-3">(</span><span class="p" data-group-id="2290492515-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2290492515-4">&gt;&gt;</span><span class="p" data-group-id="2290492515-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">after_zero</span><span class="p" data-group-id="2290492515-5">(</span><span class="n">T</span><span class="p" data-group-id="2290492515-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="2290492515-6">(</span><span class="p" data-group-id="2290492515-7">&lt;&lt;</span><span class="p" data-group-id="2290492515-7">&gt;&gt;</span><span class="p" data-group-id="2290492515-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2290492515-8">&lt;&lt;</span><span class="p" data-group-id="2290492515-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>Yes, it will. The compiler will remove the building of the sub binary in the
│ │ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="5314813250-3">(</span><span class="p" data-group-id="5314813250-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5314813250-4">&gt;&gt;</span><span class="p" data-group-id="5314813250-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">after_zero</span><span class="p" data-group-id="5314813250-5">(</span><span class="n">T</span><span class="p" data-group-id="5314813250-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="5314813250-6">(</span><span class="p" data-group-id="5314813250-7">&lt;&lt;</span><span class="p" data-group-id="5314813250-7">&gt;&gt;</span><span class="p" data-group-id="5314813250-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="5314813250-8">&lt;&lt;</span><span class="p" data-group-id="5314813250-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>Yes, it will. The compiler will remove the building of the sub binary in the
│ │ │ │  second clause:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="5860356833-1">(</span><span class="p" data-group-id="5860356833-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5860356833-2">&gt;&gt;</span><span class="p" data-group-id="5860356833-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">after_zero</span><span class="p" data-group-id="5860356833-3">(</span><span class="n">T</span><span class="p" data-group-id="5860356833-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>But it will generate code that builds a sub binary in the first clause:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="2578825092-1">(</span><span class="p" data-group-id="2578825092-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2578825092-2">&gt;&gt;</span><span class="p" data-group-id="2578825092-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="6048413808-1">(</span><span class="p" data-group-id="6048413808-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6048413808-2">&gt;&gt;</span><span class="p" data-group-id="6048413808-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">after_zero</span><span class="p" data-group-id="6048413808-3">(</span><span class="n">T</span><span class="p" data-group-id="6048413808-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>But it will generate code that builds a sub binary in the first clause:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="9093579743-1">(</span><span class="p" data-group-id="9093579743-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9093579743-2">&gt;&gt;</span><span class="p" data-group-id="9093579743-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">T</span><span class="p">;</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Therefore, <code class="inline">after_zero/1</code> builds one match context and one sub binary (assuming
│ │ │ │ -it is passed a binary that contains a zero byte).</p><p>Code like the following will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="3462212955-1">(</span><span class="n">Buffer</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3462212955-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3462212955-2">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="3462212955-3">(</span><span class="n">Acc</span><span class="p" data-group-id="3462212955-3">)</span><span class="p">,</span><span class="n">Buffer</span><span class="p" data-group-id="3462212955-2">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="3462212955-4">(</span><span class="p" data-group-id="3462212955-5">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3462212955-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="3462212955-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="3462212955-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="3462212955-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="3462212955-7">(</span><span class="p" data-group-id="3462212955-8">&lt;&lt;</span><span class="n">Byte</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3462212955-8">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="3462212955-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="3462212955-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3462212955-10">[</span><span class="n">Byte</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="3462212955-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="3462212955-9">)</span><span class="p">.</span></code></pre><p>The compiler removes building of sub binaries in the second and third clauses,
│ │ │ │ +it is passed a binary that contains a zero byte).</p><p>Code like the following will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="2986846701-1">(</span><span class="n">Buffer</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="2986846701-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2986846701-2">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="2986846701-3">(</span><span class="n">Acc</span><span class="p" data-group-id="2986846701-3">)</span><span class="p">,</span><span class="n">Buffer</span><span class="p" data-group-id="2986846701-2">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="2986846701-4">(</span><span class="p" data-group-id="2986846701-5">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2986846701-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="2986846701-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="2986846701-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="2986846701-6">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="2986846701-7">(</span><span class="p" data-group-id="2986846701-8">&lt;&lt;</span><span class="n">Byte</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2986846701-8">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="2986846701-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="2986846701-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2986846701-10">[</span><span class="n">Byte</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="2986846701-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="2986846701-9">)</span><span class="p">.</span></code></pre><p>The compiler removes building of sub binaries in the second and third clauses,
│ │ │ │  and it adds an instruction to the first clause that converts <code class="inline">Buffer</code> from a
│ │ │ │  match context to a sub binary (or do nothing if <code class="inline">Buffer</code> is a binary already).</p><p>But in more complicated code, how can one know whether the optimization is
│ │ │ │  applied or not?</p><p><a href="" id="bin_opt_info"></a></p><h3 id="option-bin_opt_info" class="section-heading">
│ │ │ │    <a href="#option-bin_opt_info" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Option bin_opt_info</span>
│ │ │ │ @@ -259,35 +259,35 @@
│ │ │ │  <p>Use the <code class="inline">bin_opt_info</code> option to have the compiler print a lot of information
│ │ │ │  about binary optimizations. It can be given either to the compiler or <code class="inline">erlc</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">erlc</span><span class="w"> </span><span class="o">+</span><span class="ss">bin_opt_info</span><span class="w"> </span><span class="n">Mod</span><span class="p">.</span><span class="ss">erl</span></code></pre><p>or passed through an environment variable:</p><pre><code class="makeup erlang" translate="no"><span class="ss">export</span><span class="w"> </span><span class="n">ERL_COMPILER_OPTIONS</span><span class="o">=</span><span class="ss">bin_opt_info</span></code></pre><p>Notice that the <code class="inline">bin_opt_info</code> is not meant to be a permanent option added to
│ │ │ │  your <code class="inline">Makefile</code>s, because all messages that it generates cannot be eliminated.
│ │ │ │  Therefore, passing the option through the environment is in most cases the most
│ │ │ │  practical approach.</p><p>The warnings look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="o">/</span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">60</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">NOT</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">binary</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">returned</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">function</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="o">/</span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">62</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">context</span><span class="w"> </span><span class="ss">reused</span></code></pre><p>To make it clearer exactly what code the warnings refer to, the warnings in the
│ │ │ │  following examples are inserted as comments after the clause they refer to, for
│ │ │ │ -example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="9601359651-1">(</span><span class="p" data-group-id="9601359651-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9601359651-2">&gt;&gt;</span><span class="p" data-group-id="9601359651-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="7191570979-1">(</span><span class="p" data-group-id="7191570979-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7191570979-2">&gt;&gt;</span><span class="p" data-group-id="7191570979-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │           </span><span class="c1">%% BINARY CREATED: binary is returned from the function</span><span class="w">
│ │ │ │      </span><span class="n">T</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="9601359651-3">(</span><span class="p" data-group-id="9601359651-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9601359651-4">&gt;&gt;</span><span class="p" data-group-id="9601359651-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="7191570979-3">(</span><span class="p" data-group-id="7191570979-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7191570979-4">&gt;&gt;</span><span class="p" data-group-id="7191570979-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │           </span><span class="c1">%% OPTIMIZED: match context reused</span><span class="w">
│ │ │ │ -    </span><span class="nf">after_zero</span><span class="p" data-group-id="9601359651-5">(</span><span class="n">T</span><span class="p" data-group-id="9601359651-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="9601359651-6">(</span><span class="p" data-group-id="9601359651-7">&lt;&lt;</span><span class="p" data-group-id="9601359651-7">&gt;&gt;</span><span class="p" data-group-id="9601359651-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9601359651-8">&lt;&lt;</span><span class="p" data-group-id="9601359651-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>The warning for the first clause says that the creation of a sub binary cannot
│ │ │ │ +    </span><span class="nf">after_zero</span><span class="p" data-group-id="7191570979-5">(</span><span class="n">T</span><span class="p" data-group-id="7191570979-5">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="7191570979-6">(</span><span class="p" data-group-id="7191570979-7">&lt;&lt;</span><span class="p" data-group-id="7191570979-7">&gt;&gt;</span><span class="p" data-group-id="7191570979-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="7191570979-8">&lt;&lt;</span><span class="p" data-group-id="7191570979-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>The warning for the first clause says that the creation of a sub binary cannot
│ │ │ │  be delayed, because it will be returned. The warning for the second clause says
│ │ │ │  that a sub binary will not be created (yet).</p><h3 id="unused-variables" class="section-heading">
│ │ │ │    <a href="#unused-variables" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Unused Variables</span>
│ │ │ │  </h3>
│ │ │ │  <p>The compiler figures out if a variable is unused. The same code is generated for
│ │ │ │ -each of the following functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">count1</span><span class="p" data-group-id="4464874304-1">(</span><span class="p" data-group-id="4464874304-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4464874304-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4464874304-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count1</span><span class="p" data-group-id="4464874304-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="4464874304-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">count1</span><span class="p" data-group-id="4464874304-4">(</span><span class="p" data-group-id="4464874304-5">&lt;&lt;</span><span class="p" data-group-id="4464874304-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4464874304-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │ │ +each of the following functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">count1</span><span class="p" data-group-id="4211152986-1">(</span><span class="p" data-group-id="4211152986-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4211152986-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4211152986-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count1</span><span class="p" data-group-id="4211152986-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="4211152986-3">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">count1</span><span class="p" data-group-id="4211152986-4">(</span><span class="p" data-group-id="4211152986-5">&lt;&lt;</span><span class="p" data-group-id="4211152986-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4211152986-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">count2</span><span class="p" data-group-id="4464874304-6">(</span><span class="p" data-group-id="4464874304-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4464874304-7">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4464874304-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count2</span><span class="p" data-group-id="4464874304-8">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="4464874304-8">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">count2</span><span class="p" data-group-id="4464874304-9">(</span><span class="p" data-group-id="4464874304-10">&lt;&lt;</span><span class="p" data-group-id="4464874304-10">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4464874304-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">count2</span><span class="p" data-group-id="4211152986-6">(</span><span class="p" data-group-id="4211152986-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4211152986-7">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4211152986-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count2</span><span class="p" data-group-id="4211152986-8">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="4211152986-8">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">count2</span><span class="p" data-group-id="4211152986-9">(</span><span class="p" data-group-id="4211152986-10">&lt;&lt;</span><span class="p" data-group-id="4211152986-10">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4211152986-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">count3</span><span class="p" data-group-id="4464874304-11">(</span><span class="p" data-group-id="4464874304-12">&lt;&lt;</span><span class="p">_</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4464874304-12">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4464874304-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count3</span><span class="p" data-group-id="4464874304-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="4464874304-13">)</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">count3</span><span class="p" data-group-id="4464874304-14">(</span><span class="p" data-group-id="4464874304-15">&lt;&lt;</span><span class="p" data-group-id="4464874304-15">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4464874304-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span></code></pre><p>In each iteration, the first 8 bits in the binary will be skipped, not matched
│ │ │ │ +</span><span class="nf">count3</span><span class="p" data-group-id="4211152986-11">(</span><span class="p" data-group-id="4211152986-12">&lt;&lt;</span><span class="p">_</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4211152986-12">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4211152986-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count3</span><span class="p" data-group-id="4211152986-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="4211152986-13">)</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">count3</span><span class="p" data-group-id="4211152986-14">(</span><span class="p" data-group-id="4211152986-15">&lt;&lt;</span><span class="p" data-group-id="4211152986-15">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="4211152986-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span></code></pre><p>In each iteration, the first 8 bits in the binary will be skipped, not matched
│ │ │ │  out.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/benchmarking.xhtml
│ │ │ │ @@ -49,16 +49,16 @@
│ │ │ │  fast as possible, what can we do? One way could be to generate more
│ │ │ │  than two bytes at the time.</p><pre><code class="text">% erlperf 'rand:bytes(100).' 'crypto:strong_rand_bytes(100).'
│ │ │ │  Code                                   ||        QPS       Time   Rel
│ │ │ │  rand:bytes(100).                        1    2124 Ki     470 ns  100%
│ │ │ │  crypto:strong_rand_bytes(100).          1    1915 Ki     522 ns   90%</code></pre><p><a href="../../../lib/stdlib/doc/html/rand.html#bytes/1"><code class="inline">rand:bytes/1</code></a> is still faster when we generate 100 bytes at the time,
│ │ │ │  but the relative difference is smaller.</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erlperf &#39;rand:bytes(1000).&#39; &#39;crypto:strong_rand_bytes(1000).&#39;</span><span class="w">
│ │ │ │  </span><span class="n">Code</span><span class="w">                                    </span><span class="p">||</span><span class="w">        </span><span class="n">QPS</span><span class="w">       </span><span class="n">Time</span><span class="w">   </span><span class="n">Rel</span><span class="w">
│ │ │ │ -</span><span class="nc">crypto</span><span class="p">:</span><span class="nf">strong_rand_bytes</span><span class="p" data-group-id="7503281122-1">(</span><span class="mi">1000</span><span class="p" data-group-id="7503281122-1">)</span><span class="p">.</span><span class="w">          </span><span class="mi">1</span><span class="w">    </span><span class="mi">1518</span><span class="w"> </span><span class="n">Ki</span><span class="w">     </span><span class="mi">658</span><span class="w"> </span><span class="ss">ns</span><span class="w">  </span><span class="mi">100</span><span class="c1">%</span><span class="w">
│ │ │ │ -</span><span class="nc">rand</span><span class="p">:</span><span class="nf">bytes</span><span class="p" data-group-id="7503281122-2">(</span><span class="mi">1000</span><span class="p" data-group-id="7503281122-2">)</span><span class="p">.</span><span class="w">                        </span><span class="mi">1</span><span class="w">     </span><span class="mi">284</span><span class="w"> </span><span class="n">Ki</span><span class="w">    </span><span class="mi">3521</span><span class="w"> </span><span class="ss">ns</span><span class="w">   </span><span class="mi">19</span><span class="c1">%</span></code></pre><p>When we generate 1000 bytes at the time, <a href="../../../lib/crypto/doc/html/crypto.html#strong_rand_bytes/1"><code class="inline">crypto:strong_rand_bytes/1</code></a> is
│ │ │ │ +</span><span class="nc">crypto</span><span class="p">:</span><span class="nf">strong_rand_bytes</span><span class="p" data-group-id="2167385103-1">(</span><span class="mi">1000</span><span class="p" data-group-id="2167385103-1">)</span><span class="p">.</span><span class="w">          </span><span class="mi">1</span><span class="w">    </span><span class="mi">1518</span><span class="w"> </span><span class="n">Ki</span><span class="w">     </span><span class="mi">658</span><span class="w"> </span><span class="ss">ns</span><span class="w">  </span><span class="mi">100</span><span class="c1">%</span><span class="w">
│ │ │ │ +</span><span class="nc">rand</span><span class="p">:</span><span class="nf">bytes</span><span class="p" data-group-id="2167385103-2">(</span><span class="mi">1000</span><span class="p" data-group-id="2167385103-2">)</span><span class="p">.</span><span class="w">                        </span><span class="mi">1</span><span class="w">     </span><span class="mi">284</span><span class="w"> </span><span class="n">Ki</span><span class="w">    </span><span class="mi">3521</span><span class="w"> </span><span class="ss">ns</span><span class="w">   </span><span class="mi">19</span><span class="c1">%</span></code></pre><p>When we generate 1000 bytes at the time, <a href="../../../lib/crypto/doc/html/crypto.html#strong_rand_bytes/1"><code class="inline">crypto:strong_rand_bytes/1</code></a> is
│ │ │ │  now the fastest.</p><h2 id="benchmarking-using-erlang-otp-functionality" class="section-heading">
│ │ │ │    <a href="#benchmarking-using-erlang-otp-functionality" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Benchmarking using Erlang/OTP functionality</span>
│ │ │ │  </h2>
│ │ │ │  <p>Benchmarks can measure wall-clock time or CPU time.</p><ul><li><p><a href="../../../lib/stdlib/doc/html/timer.html#tc/3"><code class="inline">timer:tc/3</code></a> measures wall-clock time. The advantage with wall-clock time is
│ │ │ ├── OEBPS/appup_cookbook.xhtml
│ │ │ │ @@ -25,18 +25,18 @@
│ │ │ │    <a href="#changing-a-functional-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing a Functional Module</span>
│ │ │ │  </h2>
│ │ │ │  <p>When a functional module has been changed, for example, if a new function has
│ │ │ │  been added or a bug has been corrected, simple code replacement is sufficient,
│ │ │ │ -for example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7528884188-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7528884188-2">[</span><span class="p" data-group-id="7528884188-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7528884188-4">[</span><span class="p" data-group-id="7528884188-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="7528884188-5">}</span><span class="p" data-group-id="7528884188-4">]</span><span class="p" data-group-id="7528884188-3">}</span><span class="p" data-group-id="7528884188-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7528884188-6">[</span><span class="p" data-group-id="7528884188-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7528884188-8">[</span><span class="p" data-group-id="7528884188-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="7528884188-9">}</span><span class="p" data-group-id="7528884188-8">]</span><span class="p" data-group-id="7528884188-7">}</span><span class="p" data-group-id="7528884188-6">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="7528884188-1">}</span><span class="p">.</span></code></pre><h2 id="changing-a-residence-module" class="section-heading">
│ │ │ │ +for example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1177859469-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="1177859469-2">[</span><span class="p" data-group-id="1177859469-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1177859469-4">[</span><span class="p" data-group-id="1177859469-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="1177859469-5">}</span><span class="p" data-group-id="1177859469-4">]</span><span class="p" data-group-id="1177859469-3">}</span><span class="p" data-group-id="1177859469-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="1177859469-6">[</span><span class="p" data-group-id="1177859469-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1177859469-8">[</span><span class="p" data-group-id="1177859469-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="1177859469-9">}</span><span class="p" data-group-id="1177859469-8">]</span><span class="p" data-group-id="1177859469-7">}</span><span class="p" data-group-id="1177859469-6">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1177859469-1">}</span><span class="p">.</span></code></pre><h2 id="changing-a-residence-module" class="section-heading">
│ │ │ │    <a href="#changing-a-residence-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing a Residence Module</span>
│ │ │ │  </h2>
│ │ │ │  <p>In a system implemented according to the OTP design principles, all processes,
│ │ │ │  except system processes and special processes, reside in one of the behaviours
│ │ │ │ @@ -47,46 +47,46 @@
│ │ │ │    <a href="#changing-a-callback-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing a Callback Module</span>
│ │ │ │  </h2>
│ │ │ │  <p>A callback module is a functional module, and for code extensions simple code
│ │ │ │  replacement is sufficient.</p><p><em>Example</em></p><p>When adding a function to <code class="inline">ch3</code>, as described in the example in
│ │ │ │ -<a href="release_handling.xhtml#appup">Release Handling</a>, <code class="inline">ch_app.appup</code> looks as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3078525223-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="3078525223-2">[</span><span class="p" data-group-id="3078525223-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3078525223-4">[</span><span class="p" data-group-id="3078525223-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3078525223-5">}</span><span class="p" data-group-id="3078525223-4">]</span><span class="p" data-group-id="3078525223-3">}</span><span class="p" data-group-id="3078525223-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="3078525223-6">[</span><span class="p" data-group-id="3078525223-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3078525223-8">[</span><span class="p" data-group-id="3078525223-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3078525223-9">}</span><span class="p" data-group-id="3078525223-8">]</span><span class="p" data-group-id="3078525223-7">}</span><span class="p" data-group-id="3078525223-6">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="3078525223-1">}</span><span class="p">.</span></code></pre><p>OTP also supports changing the internal state of behaviour processes; see
│ │ │ │ +<a href="release_handling.xhtml#appup">Release Handling</a>, <code class="inline">ch_app.appup</code> looks as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2660372096-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2660372096-2">[</span><span class="p" data-group-id="2660372096-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2660372096-4">[</span><span class="p" data-group-id="2660372096-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="2660372096-5">}</span><span class="p" data-group-id="2660372096-4">]</span><span class="p" data-group-id="2660372096-3">}</span><span class="p" data-group-id="2660372096-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2660372096-6">[</span><span class="p" data-group-id="2660372096-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2660372096-8">[</span><span class="p" data-group-id="2660372096-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="2660372096-9">}</span><span class="p" data-group-id="2660372096-8">]</span><span class="p" data-group-id="2660372096-7">}</span><span class="p" data-group-id="2660372096-6">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2660372096-1">}</span><span class="p">.</span></code></pre><p>OTP also supports changing the internal state of behaviour processes; see
│ │ │ │  <a href="appup_cookbook.xhtml#int_state">Changing Internal State</a>.</p><p><a href="" id="int_state"></a></p><h2 id="changing-internal-state" class="section-heading">
│ │ │ │    <a href="#changing-internal-state" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing Internal State</span>
│ │ │ │  </h2>
│ │ │ │  <p>In this case, simple code replacement is not sufficient. The process must
│ │ │ │  explicitly transform its state using the callback function <code class="inline">code_change/3</code> before
│ │ │ │  switching to the new version of the callback module. Thus, synchronized code
│ │ │ │  replacement is used.</p><p><em>Example</em></p><p>Consider the <code class="inline">ch3</code> module from
│ │ │ │  <a href="gen_server_concepts.xhtml#ex">gen_server Behaviour</a>. The internal state is a term
│ │ │ │  <code class="inline">Chs</code> representing the available channels. Assume you want to add a counter <code class="inline">N</code>,
│ │ │ │  which keeps track of the number of <code class="inline">alloc</code> requests so far. This means that the
│ │ │ │ -format must be changed to <code class="inline">{Chs,N}</code>.</p><p>The <code class="inline">.appup</code> file can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5057715117-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="5057715117-2">[</span><span class="p" data-group-id="5057715117-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5057715117-4">[</span><span class="p" data-group-id="5057715117-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5057715117-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5057715117-7">[</span><span class="p" data-group-id="5057715117-7">]</span><span class="p" data-group-id="5057715117-6">}</span><span class="p" data-group-id="5057715117-5">}</span><span class="p" data-group-id="5057715117-4">]</span><span class="p" data-group-id="5057715117-3">}</span><span class="p" data-group-id="5057715117-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="5057715117-8">[</span><span class="p" data-group-id="5057715117-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5057715117-10">[</span><span class="p" data-group-id="5057715117-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5057715117-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5057715117-13">[</span><span class="p" data-group-id="5057715117-13">]</span><span class="p" data-group-id="5057715117-12">}</span><span class="p" data-group-id="5057715117-11">}</span><span class="p" data-group-id="5057715117-10">]</span><span class="p" data-group-id="5057715117-9">}</span><span class="p" data-group-id="5057715117-8">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5057715117-1">}</span><span class="p">.</span></code></pre><p>The third element of the <code class="inline">update</code> instruction is a tuple <code class="inline">{advanced,Extra}</code>,
│ │ │ │ +format must be changed to <code class="inline">{Chs,N}</code>.</p><p>The <code class="inline">.appup</code> file can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7098524386-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7098524386-2">[</span><span class="p" data-group-id="7098524386-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7098524386-4">[</span><span class="p" data-group-id="7098524386-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7098524386-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7098524386-7">[</span><span class="p" data-group-id="7098524386-7">]</span><span class="p" data-group-id="7098524386-6">}</span><span class="p" data-group-id="7098524386-5">}</span><span class="p" data-group-id="7098524386-4">]</span><span class="p" data-group-id="7098524386-3">}</span><span class="p" data-group-id="7098524386-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7098524386-8">[</span><span class="p" data-group-id="7098524386-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7098524386-10">[</span><span class="p" data-group-id="7098524386-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7098524386-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7098524386-13">[</span><span class="p" data-group-id="7098524386-13">]</span><span class="p" data-group-id="7098524386-12">}</span><span class="p" data-group-id="7098524386-11">}</span><span class="p" data-group-id="7098524386-10">]</span><span class="p" data-group-id="7098524386-9">}</span><span class="p" data-group-id="7098524386-8">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7098524386-1">}</span><span class="p">.</span></code></pre><p>The third element of the <code class="inline">update</code> instruction is a tuple <code class="inline">{advanced,Extra}</code>,
│ │ │ │  which says that the affected processes are to do a state transformation before
│ │ │ │  loading the new version of the module. This is done by the processes calling the
│ │ │ │  callback function <code class="inline">code_change/3</code> (see <a href="../../../lib/stdlib/doc/html/gen_server.html"><code class="inline">gen_server</code></a> in STDLIB).
│ │ │ │ -The term <code class="inline">Extra</code>, in this case <code class="inline">[]</code>, is passed as is to the function:</p><p><a href="" id="code_change"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5548136540-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="5548136540-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +The term <code class="inline">Extra</code>, in this case <code class="inline">[]</code>, is passed as is to the function:</p><p><a href="" id="code_change"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3665711888-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="3665711888-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5548136540-2">(</span><span class="p" data-group-id="5548136540-3">[</span><span class="ss">code_change</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5548136540-3">]</span><span class="p" data-group-id="5548136540-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3665711888-2">(</span><span class="p" data-group-id="3665711888-3">[</span><span class="ss">code_change</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="3665711888-3">]</span><span class="p" data-group-id="3665711888-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="nf">code_change</span><span class="p" data-group-id="5548136540-4">(</span><span class="p" data-group-id="5548136540-5">{</span><span class="ss">down</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vsn</span><span class="p" data-group-id="5548136540-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5548136540-6">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p" data-group-id="5548136540-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="5548136540-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5548136540-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="5548136540-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ -</span><span class="nf">code_change</span><span class="p" data-group-id="5548136540-8">(</span><span class="p">_</span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="5548136540-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5548136540-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5548136540-10">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="5548136540-10">}</span><span class="p" data-group-id="5548136540-9">}</span><span class="p">.</span></code></pre><p>The first argument is <code class="inline">{down,Vsn}</code> if there is a downgrade, or <code class="inline">Vsn</code> if there is
│ │ │ │ +</span><span class="nf">code_change</span><span class="p" data-group-id="3665711888-4">(</span><span class="p" data-group-id="3665711888-5">{</span><span class="ss">down</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vsn</span><span class="p" data-group-id="3665711888-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3665711888-6">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p" data-group-id="3665711888-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="3665711888-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3665711888-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3665711888-7">}</span><span class="p">;</span><span class="w">
│ │ │ │ +</span><span class="nf">code_change</span><span class="p" data-group-id="3665711888-8">(</span><span class="p">_</span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="3665711888-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="3665711888-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3665711888-10">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3665711888-10">}</span><span class="p" data-group-id="3665711888-9">}</span><span class="p">.</span></code></pre><p>The first argument is <code class="inline">{down,Vsn}</code> if there is a downgrade, or <code class="inline">Vsn</code> if there is
│ │ │ │  a upgrade. The term <code class="inline">Vsn</code> is fetched from the 'original' version of the module,
│ │ │ │  that is, the version you are upgrading from, or downgrading to.</p><p>The version is defined by the module attribute <code class="inline">vsn</code>, if any. There is no such
│ │ │ │  attribute in <code class="inline">ch3</code>, so in this case the version is the checksum (a huge integer)
│ │ │ │  of the beam file, an uninteresting value, which is ignored.</p><p>The other callback functions of <code class="inline">ch3</code> must also be modified and perhaps a new
│ │ │ │  interface function must be added, but this is not shown here.</p><h2 id="module-dependencies" class="section-heading">
│ │ │ │    <a href="#module-dependencies" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │ @@ -95,67 +95,67 @@
│ │ │ │  </h2>
│ │ │ │  <p>Assume that a module is extended by adding an interface function, as in the
│ │ │ │  example in <a href="release_handling.xhtml#appup">Release Handling</a>, where a function
│ │ │ │  <code class="inline">available/0</code> is added to <code class="inline">ch3</code>.</p><p>If a call is added to this function, say in module <code class="inline">m1</code>, a runtime error could
│ │ │ │  can occur during release upgrade if the new version of <code class="inline">m1</code> is loaded first and
│ │ │ │  calls <code class="inline">ch3:available/0</code> before the new version of <code class="inline">ch3</code> is loaded.</p><p>Thus, <code class="inline">ch3</code> must be loaded before <code class="inline">m1</code>, in the upgrade case, and conversely in
│ │ │ │  the downgrade case. <code class="inline">m1</code> is said to be <em>dependent on</em> <code class="inline">ch3</code>. In a release
│ │ │ │ -handling instruction, this is expressed by the <code class="inline">DepMods</code> element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6457705043-1">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="6457705043-1">}</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="6457705043-2">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6457705043-3">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="6457705043-3">}</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="6457705043-2">}</span></code></pre><p><code class="inline">DepMods</code> is a list of modules, on which <code class="inline">Module</code> is dependent.</p><p><em>Example</em></p><p>The module <code class="inline">m1</code> in application <code class="inline">myapp</code> is dependent on <code class="inline">ch3</code> when
│ │ │ │ +handling instruction, this is expressed by the <code class="inline">DepMods</code> element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1636020704-1">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="1636020704-1">}</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1636020704-2">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1636020704-3">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="1636020704-3">}</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="1636020704-2">}</span></code></pre><p><code class="inline">DepMods</code> is a list of modules, on which <code class="inline">Module</code> is dependent.</p><p><em>Example</em></p><p>The module <code class="inline">m1</code> in application <code class="inline">myapp</code> is dependent on <code class="inline">ch3</code> when
│ │ │ │  upgrading from &quot;1&quot; to &quot;2&quot;, or downgrading from &quot;2&quot; to &quot;1&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="ss">myapp</span><span class="p">.</span><span class="nc">appup</span><span class="p">:</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="p" data-group-id="1744504462-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1744504462-2">[</span><span class="p" data-group-id="1744504462-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1744504462-4">[</span><span class="p" data-group-id="1744504462-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1744504462-6">[</span><span class="ss">ch3</span><span class="p" data-group-id="1744504462-6">]</span><span class="p" data-group-id="1744504462-5">}</span><span class="p" data-group-id="1744504462-4">]</span><span class="p" data-group-id="1744504462-3">}</span><span class="p" data-group-id="1744504462-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1744504462-7">[</span><span class="p" data-group-id="1744504462-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1744504462-9">[</span><span class="p" data-group-id="1744504462-10">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1744504462-11">[</span><span class="ss">ch3</span><span class="p" data-group-id="1744504462-11">]</span><span class="p" data-group-id="1744504462-10">}</span><span class="p" data-group-id="1744504462-9">]</span><span class="p" data-group-id="1744504462-8">}</span><span class="p" data-group-id="1744504462-7">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1744504462-1">}</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8972659339-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8972659339-2">[</span><span class="p" data-group-id="8972659339-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8972659339-4">[</span><span class="p" data-group-id="8972659339-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8972659339-6">[</span><span class="ss">ch3</span><span class="p" data-group-id="8972659339-6">]</span><span class="p" data-group-id="8972659339-5">}</span><span class="p" data-group-id="8972659339-4">]</span><span class="p" data-group-id="8972659339-3">}</span><span class="p" data-group-id="8972659339-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8972659339-7">[</span><span class="p" data-group-id="8972659339-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8972659339-9">[</span><span class="p" data-group-id="8972659339-10">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8972659339-11">[</span><span class="ss">ch3</span><span class="p" data-group-id="8972659339-11">]</span><span class="p" data-group-id="8972659339-10">}</span><span class="p" data-group-id="8972659339-9">]</span><span class="p" data-group-id="8972659339-8">}</span><span class="p" data-group-id="8972659339-7">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8972659339-1">}</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │  </span><span class="ss">ch_app</span><span class="p">.</span><span class="nc">appup</span><span class="p">:</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="p" data-group-id="1744504462-12">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1744504462-13">[</span><span class="p" data-group-id="1744504462-14">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1744504462-15">[</span><span class="p" data-group-id="1744504462-16">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1744504462-16">}</span><span class="p" data-group-id="1744504462-15">]</span><span class="p" data-group-id="1744504462-14">}</span><span class="p" data-group-id="1744504462-13">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1744504462-17">[</span><span class="p" data-group-id="1744504462-18">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1744504462-19">[</span><span class="p" data-group-id="1744504462-20">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1744504462-20">}</span><span class="p" data-group-id="1744504462-19">]</span><span class="p" data-group-id="1744504462-18">}</span><span class="p" data-group-id="1744504462-17">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1744504462-12">}</span><span class="p">.</span></code></pre><p>If instead <code class="inline">m1</code> and <code class="inline">ch3</code> belong to the same application, the <code class="inline">.appup</code> file can
│ │ │ │ -look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4278754831-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4278754831-2">[</span><span class="p" data-group-id="4278754831-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="4278754831-4">[</span><span class="p" data-group-id="4278754831-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="4278754831-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4278754831-6">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4278754831-7">[</span><span class="ss">ch3</span><span class="p" data-group-id="4278754831-7">]</span><span class="p" data-group-id="4278754831-6">}</span><span class="p" data-group-id="4278754831-4">]</span><span class="p" data-group-id="4278754831-3">}</span><span class="p" data-group-id="4278754831-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4278754831-8">[</span><span class="p" data-group-id="4278754831-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="4278754831-10">[</span><span class="p" data-group-id="4278754831-11">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="4278754831-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4278754831-12">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4278754831-13">[</span><span class="ss">ch3</span><span class="p" data-group-id="4278754831-13">]</span><span class="p" data-group-id="4278754831-12">}</span><span class="p" data-group-id="4278754831-10">]</span><span class="p" data-group-id="4278754831-9">}</span><span class="p" data-group-id="4278754831-8">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4278754831-1">}</span><span class="p">.</span></code></pre><p><code class="inline">m1</code> is dependent on <code class="inline">ch3</code> also when downgrading. <code class="inline">systools</code> knows the
│ │ │ │ +</span><span class="p" data-group-id="8972659339-12">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8972659339-13">[</span><span class="p" data-group-id="8972659339-14">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8972659339-15">[</span><span class="p" data-group-id="8972659339-16">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8972659339-16">}</span><span class="p" data-group-id="8972659339-15">]</span><span class="p" data-group-id="8972659339-14">}</span><span class="p" data-group-id="8972659339-13">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8972659339-17">[</span><span class="p" data-group-id="8972659339-18">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8972659339-19">[</span><span class="p" data-group-id="8972659339-20">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8972659339-20">}</span><span class="p" data-group-id="8972659339-19">]</span><span class="p" data-group-id="8972659339-18">}</span><span class="p" data-group-id="8972659339-17">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8972659339-12">}</span><span class="p">.</span></code></pre><p>If instead <code class="inline">m1</code> and <code class="inline">ch3</code> belong to the same application, the <code class="inline">.appup</code> file can
│ │ │ │ +look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0560837148-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="0560837148-2">[</span><span class="p" data-group-id="0560837148-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="0560837148-4">[</span><span class="p" data-group-id="0560837148-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="0560837148-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0560837148-6">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0560837148-7">[</span><span class="ss">ch3</span><span class="p" data-group-id="0560837148-7">]</span><span class="p" data-group-id="0560837148-6">}</span><span class="p" data-group-id="0560837148-4">]</span><span class="p" data-group-id="0560837148-3">}</span><span class="p" data-group-id="0560837148-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="0560837148-8">[</span><span class="p" data-group-id="0560837148-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="0560837148-10">[</span><span class="p" data-group-id="0560837148-11">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="0560837148-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0560837148-12">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0560837148-13">[</span><span class="ss">ch3</span><span class="p" data-group-id="0560837148-13">]</span><span class="p" data-group-id="0560837148-12">}</span><span class="p" data-group-id="0560837148-10">]</span><span class="p" data-group-id="0560837148-9">}</span><span class="p" data-group-id="0560837148-8">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0560837148-1">}</span><span class="p">.</span></code></pre><p><code class="inline">m1</code> is dependent on <code class="inline">ch3</code> also when downgrading. <code class="inline">systools</code> knows the
│ │ │ │  difference between up- and downgrading and generates a correct <code class="inline">relup</code>, where
│ │ │ │  <code class="inline">ch3</code> is loaded before <code class="inline">m1</code> when upgrading, but <code class="inline">m1</code> is loaded before <code class="inline">ch3</code> when
│ │ │ │  downgrading.</p><p><a href="" id="spec"></a></p><h2 id="changing-code-for-a-special-process" class="section-heading">
│ │ │ │    <a href="#changing-code-for-a-special-process" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing Code for a Special Process</span>
│ │ │ │  </h2>
│ │ │ │  <p>In this case, simple code replacement is not sufficient. When a new version of a
│ │ │ │  residence module for a special process is loaded, the process must make a fully
│ │ │ │  qualified call to its loop function to switch to the new code. Thus,
│ │ │ │  synchronized code replacement must be used.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The name(s) of the user-defined residence module(s) must be listed in the
│ │ │ │  <code class="inline">Modules</code> part of the child specification for the special process. Otherwise
│ │ │ │  the release handler cannot find the process.</p></section><p><em>Example</em></p><p>Consider the example <code class="inline">ch4</code> in <a href="spec_proc.xhtml#ex">sys and proc_lib</a>.
│ │ │ │ -When started by a supervisor, the child specification can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8688651614-1">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688651614-2">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688651614-3">[</span><span class="p" data-group-id="8688651614-3">]</span><span class="p" data-group-id="8688651614-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="ss">permanent</span><span class="p">,</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688651614-4">[</span><span class="ss">ch4</span><span class="p" data-group-id="8688651614-4">]</span><span class="p" data-group-id="8688651614-1">}</span></code></pre><p>If <code class="inline">ch4</code> is part of the application <code class="inline">sp_app</code> and a new version of the module is
│ │ │ │ +When started by a supervisor, the child specification can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6541628808-1">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6541628808-2">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6541628808-3">[</span><span class="p" data-group-id="6541628808-3">]</span><span class="p" data-group-id="6541628808-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="ss">permanent</span><span class="p">,</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6541628808-4">[</span><span class="ss">ch4</span><span class="p" data-group-id="6541628808-4">]</span><span class="p" data-group-id="6541628808-1">}</span></code></pre><p>If <code class="inline">ch4</code> is part of the application <code class="inline">sp_app</code> and a new version of the module is
│ │ │ │  to be loaded when upgrading from version &quot;1&quot; to &quot;2&quot; of this application,
│ │ │ │ -<code class="inline">sp_app.appup</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1835905265-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1835905265-2">[</span><span class="p" data-group-id="1835905265-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1835905265-4">[</span><span class="p" data-group-id="1835905265-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1835905265-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1835905265-7">[</span><span class="p" data-group-id="1835905265-7">]</span><span class="p" data-group-id="1835905265-6">}</span><span class="p" data-group-id="1835905265-5">}</span><span class="p" data-group-id="1835905265-4">]</span><span class="p" data-group-id="1835905265-3">}</span><span class="p" data-group-id="1835905265-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1835905265-8">[</span><span class="p" data-group-id="1835905265-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1835905265-10">[</span><span class="p" data-group-id="1835905265-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1835905265-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1835905265-13">[</span><span class="p" data-group-id="1835905265-13">]</span><span class="p" data-group-id="1835905265-12">}</span><span class="p" data-group-id="1835905265-11">}</span><span class="p" data-group-id="1835905265-10">]</span><span class="p" data-group-id="1835905265-9">}</span><span class="p" data-group-id="1835905265-8">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1835905265-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">update</code> instruction must contain the tuple <code class="inline">{advanced,Extra}</code>. The
│ │ │ │ +<code class="inline">sp_app.appup</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2433742962-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2433742962-2">[</span><span class="p" data-group-id="2433742962-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2433742962-4">[</span><span class="p" data-group-id="2433742962-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2433742962-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2433742962-7">[</span><span class="p" data-group-id="2433742962-7">]</span><span class="p" data-group-id="2433742962-6">}</span><span class="p" data-group-id="2433742962-5">}</span><span class="p" data-group-id="2433742962-4">]</span><span class="p" data-group-id="2433742962-3">}</span><span class="p" data-group-id="2433742962-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2433742962-8">[</span><span class="p" data-group-id="2433742962-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2433742962-10">[</span><span class="p" data-group-id="2433742962-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2433742962-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2433742962-13">[</span><span class="p" data-group-id="2433742962-13">]</span><span class="p" data-group-id="2433742962-12">}</span><span class="p" data-group-id="2433742962-11">}</span><span class="p" data-group-id="2433742962-10">]</span><span class="p" data-group-id="2433742962-9">}</span><span class="p" data-group-id="2433742962-8">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2433742962-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">update</code> instruction must contain the tuple <code class="inline">{advanced,Extra}</code>. The
│ │ │ │  instruction makes the special process call the callback function
│ │ │ │  <code class="inline">system_code_change/4</code>, a function the user must implement. The term <code class="inline">Extra</code>, in
│ │ │ │ -this case <code class="inline">[]</code>, is passed as is to <code class="inline">system_code_change/4</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9824323085-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="9824323085-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +this case <code class="inline">[]</code>, is passed as is to <code class="inline">system_code_change/4</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2302783224-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="2302783224-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9824323085-2">(</span><span class="p" data-group-id="9824323085-3">[</span><span class="ss">system_code_change</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="9824323085-3">]</span><span class="p" data-group-id="9824323085-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2302783224-2">(</span><span class="p" data-group-id="2302783224-3">[</span><span class="ss">system_code_change</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="2302783224-3">]</span><span class="p" data-group-id="2302783224-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">system_code_change</span><span class="p" data-group-id="9824323085-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="9824323085-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="9824323085-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="9824323085-5">}</span><span class="p">.</span></code></pre><ul><li>The first argument is the internal state <code class="inline">State</code>, passed from
│ │ │ │ +</span><span class="nf">system_code_change</span><span class="p" data-group-id="2302783224-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="2302783224-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2302783224-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2302783224-5">}</span><span class="p">.</span></code></pre><ul><li>The first argument is the internal state <code class="inline">State</code>, passed from
│ │ │ │  function <a href="../../../lib/stdlib/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg(Request, From, Parent, Module, Deb, State)</code></a>, and called by the special
│ │ │ │  process when a system message is received. In <code class="inline">ch4</code>, the internal
│ │ │ │  state is the set of available channels <code class="inline">Chs</code>.</li><li>The second argument is the name of the module (<code class="inline">ch4</code>).</li><li>The third argument is <code class="inline">Vsn</code> or <code class="inline">{down,Vsn}</code>, as described for
│ │ │ │  <a href="../../../lib/stdlib/doc/html/gen_server.html#c:code_change/3"><code class="inline">gen_server:code_change/3</code></a> in
│ │ │ │  <a href="appup_cookbook.xhtml#code_change">Changing Internal State</a>.</li></ul><p>In this case, all arguments but the first are ignored and the function simply
│ │ │ │  returns the internal state again. This is enough if the code only has been
│ │ │ │  extended. If instead the internal state is changed (similar to the example in
│ │ │ │ @@ -176,85 +176,85 @@
│ │ │ │    <span class="text">Changing Properties</span>
│ │ │ │  </h3>
│ │ │ │  <p>Since the supervisor is to change its internal state, synchronized code
│ │ │ │  replacement is required. However, a special <code class="inline">update</code> instruction must be used.</p><p>First, the new version of the callback module must be loaded, both in the case
│ │ │ │  of upgrade and downgrade. Then the new return value of <code class="inline">init/1</code> can be checked
│ │ │ │  and the internal state be changed accordingly.</p><p>The following <code class="inline">upgrade</code> instruction is used for supervisors:</p><pre><code class="text">{update, Module, supervisor}</code></pre><p><em>Example</em></p><p>To change the restart strategy of <code class="inline">ch_sup</code> (from
│ │ │ │  <a href="sup_princ.xhtml#ex">Supervisor Behaviour</a>) from <code class="inline">one_for_one</code> to <code class="inline">one_for_all</code>,
│ │ │ │ -change the callback function <code class="inline">init/1</code> in <code class="inline">ch_sup.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2374800997-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="2374800997-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +change the callback function <code class="inline">init/1</code> in <code class="inline">ch_sup.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1862168205-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="1862168205-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="2374800997-2">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="2374800997-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2374800997-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2374800997-4">{</span><span class="p" data-group-id="2374800997-5">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_all</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2374800997-5">}</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2374800997-4">}</span><span class="p" data-group-id="2374800997-3">}</span><span class="p">.</span></code></pre><p>The file <code class="inline">ch_app.appup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2947679786-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2947679786-2">[</span><span class="p" data-group-id="2947679786-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2947679786-4">[</span><span class="p" data-group-id="2947679786-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2947679786-5">}</span><span class="p" data-group-id="2947679786-4">]</span><span class="p" data-group-id="2947679786-3">}</span><span class="p" data-group-id="2947679786-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2947679786-6">[</span><span class="p" data-group-id="2947679786-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2947679786-8">[</span><span class="p" data-group-id="2947679786-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2947679786-9">}</span><span class="p" data-group-id="2947679786-8">]</span><span class="p" data-group-id="2947679786-7">}</span><span class="p" data-group-id="2947679786-6">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2947679786-1">}</span><span class="p">.</span></code></pre><h3 id="changing-child-specifications" class="section-heading">
│ │ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="1862168205-2">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="1862168205-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1862168205-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1862168205-4">{</span><span class="p" data-group-id="1862168205-5">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_all</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1862168205-5">}</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1862168205-4">}</span><span class="p" data-group-id="1862168205-3">}</span><span class="p">.</span></code></pre><p>The file <code class="inline">ch_app.appup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6685279732-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="6685279732-2">[</span><span class="p" data-group-id="6685279732-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6685279732-4">[</span><span class="p" data-group-id="6685279732-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="6685279732-5">}</span><span class="p" data-group-id="6685279732-4">]</span><span class="p" data-group-id="6685279732-3">}</span><span class="p" data-group-id="6685279732-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="6685279732-6">[</span><span class="p" data-group-id="6685279732-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6685279732-8">[</span><span class="p" data-group-id="6685279732-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="6685279732-9">}</span><span class="p" data-group-id="6685279732-8">]</span><span class="p" data-group-id="6685279732-7">}</span><span class="p" data-group-id="6685279732-6">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="6685279732-1">}</span><span class="p">.</span></code></pre><h3 id="changing-child-specifications" class="section-heading">
│ │ │ │    <a href="#changing-child-specifications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing Child Specifications</span>
│ │ │ │  </h3>
│ │ │ │  <p>The instruction, and thus the <code class="inline">.appup</code> file, when changing an existing child
│ │ │ │ -specification, is the same as when changing properties as described earlier:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8771567911-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8771567911-2">[</span><span class="p" data-group-id="8771567911-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8771567911-4">[</span><span class="p" data-group-id="8771567911-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="8771567911-5">}</span><span class="p" data-group-id="8771567911-4">]</span><span class="p" data-group-id="8771567911-3">}</span><span class="p" data-group-id="8771567911-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8771567911-6">[</span><span class="p" data-group-id="8771567911-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8771567911-8">[</span><span class="p" data-group-id="8771567911-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="8771567911-9">}</span><span class="p" data-group-id="8771567911-8">]</span><span class="p" data-group-id="8771567911-7">}</span><span class="p" data-group-id="8771567911-6">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8771567911-1">}</span><span class="p">.</span></code></pre><p>The changes do not affect existing child processes. For example, changing the
│ │ │ │ +specification, is the same as when changing properties as described earlier:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2195751730-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2195751730-2">[</span><span class="p" data-group-id="2195751730-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2195751730-4">[</span><span class="p" data-group-id="2195751730-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2195751730-5">}</span><span class="p" data-group-id="2195751730-4">]</span><span class="p" data-group-id="2195751730-3">}</span><span class="p" data-group-id="2195751730-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2195751730-6">[</span><span class="p" data-group-id="2195751730-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2195751730-8">[</span><span class="p" data-group-id="2195751730-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2195751730-9">}</span><span class="p" data-group-id="2195751730-8">]</span><span class="p" data-group-id="2195751730-7">}</span><span class="p" data-group-id="2195751730-6">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2195751730-1">}</span><span class="p">.</span></code></pre><p>The changes do not affect existing child processes. For example, changing the
│ │ │ │  start function only specifies how the child process is to be restarted, if
│ │ │ │  needed later on.</p><p>The id of the child specification cannot be changed.</p><p>Changing the <code class="inline">Modules</code> field of the child specification can affect the release
│ │ │ │  handling process itself, as this field is used to identify which processes are
│ │ │ │  affected when doing a synchronized code replacement.</p><p><a href="" id="sup_add"></a></p><h3 id="adding-and-deleting-child-processes" class="section-heading">
│ │ │ │    <a href="#adding-and-deleting-child-processes" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Adding and Deleting Child Processes</span>
│ │ │ │  </h3>
│ │ │ │  <p>As stated earlier, changing child specifications does not affect existing child
│ │ │ │  processes. New child specifications are automatically added, but not deleted.
│ │ │ │  Child processes are not automatically started or terminated, this must be done
│ │ │ │  using <code class="inline">apply</code> instructions.</p><p><em>Example</em></p><p>Assume a new child process <code class="inline">m1</code> is to be added to <code class="inline">ch_sup</code> when
│ │ │ │  upgrading <code class="inline">ch_app</code> from &quot;1&quot; to &quot;2&quot;. This means <code class="inline">m1</code> is to be deleted when
│ │ │ │ -downgrading from &quot;2&quot; to &quot;1&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1107870629-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1107870629-2">[</span><span class="p" data-group-id="1107870629-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="1107870629-4">[</span><span class="p" data-group-id="1107870629-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1107870629-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1107870629-6">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1107870629-7">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1107870629-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1107870629-8">]</span><span class="p" data-group-id="1107870629-7">}</span><span class="p" data-group-id="1107870629-6">}</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="1107870629-4">]</span><span class="p" data-group-id="1107870629-3">}</span><span class="p" data-group-id="1107870629-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1107870629-9">[</span><span class="p" data-group-id="1107870629-10">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="1107870629-11">[</span><span class="p" data-group-id="1107870629-12">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1107870629-13">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1107870629-14">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1107870629-14">]</span><span class="p" data-group-id="1107870629-13">}</span><span class="p" data-group-id="1107870629-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1107870629-15">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1107870629-16">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1107870629-17">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1107870629-17">]</span><span class="p" data-group-id="1107870629-16">}</span><span class="p" data-group-id="1107870629-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="1107870629-18">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1107870629-18">}</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="1107870629-11">]</span><span class="p" data-group-id="1107870629-10">}</span><span class="p" data-group-id="1107870629-9">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1107870629-1">}</span><span class="p">.</span></code></pre><p>The order of the instructions is important.</p><p>The supervisor must be registered as <code class="inline">ch_sup</code> for the script to work. If the
│ │ │ │ +downgrading from &quot;2&quot; to &quot;1&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8086251194-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8086251194-2">[</span><span class="p" data-group-id="8086251194-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="8086251194-4">[</span><span class="p" data-group-id="8086251194-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="8086251194-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8086251194-6">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8086251194-7">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8086251194-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8086251194-8">]</span><span class="p" data-group-id="8086251194-7">}</span><span class="p" data-group-id="8086251194-6">}</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="8086251194-4">]</span><span class="p" data-group-id="8086251194-3">}</span><span class="p" data-group-id="8086251194-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8086251194-9">[</span><span class="p" data-group-id="8086251194-10">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="8086251194-11">[</span><span class="p" data-group-id="8086251194-12">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8086251194-13">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8086251194-14">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8086251194-14">]</span><span class="p" data-group-id="8086251194-13">}</span><span class="p" data-group-id="8086251194-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8086251194-15">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8086251194-16">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8086251194-17">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8086251194-17">]</span><span class="p" data-group-id="8086251194-16">}</span><span class="p" data-group-id="8086251194-15">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="8086251194-18">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="8086251194-18">}</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="8086251194-11">]</span><span class="p" data-group-id="8086251194-10">}</span><span class="p" data-group-id="8086251194-9">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8086251194-1">}</span><span class="p">.</span></code></pre><p>The order of the instructions is important.</p><p>The supervisor must be registered as <code class="inline">ch_sup</code> for the script to work. If the
│ │ │ │  supervisor is not registered, it cannot be accessed directly from the script.
│ │ │ │  Instead a help function that finds the pid of the supervisor and calls
│ │ │ │  <code class="inline">supervisor:restart_child</code>, and so on, must be written. This function is then to
│ │ │ │  be called from the script using the <code class="inline">apply</code> instruction.</p><p>If the module <code class="inline">m1</code> is introduced in version &quot;2&quot; of <code class="inline">ch_app</code>, it must also be
│ │ │ │ -loaded when upgrading and deleted when downgrading:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4075347333-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4075347333-2">[</span><span class="p" data-group-id="4075347333-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="4075347333-4">[</span><span class="p" data-group-id="4075347333-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="4075347333-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4075347333-6">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="4075347333-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4075347333-7">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4075347333-8">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4075347333-9">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="4075347333-9">]</span><span class="p" data-group-id="4075347333-8">}</span><span class="p" data-group-id="4075347333-7">}</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="4075347333-4">]</span><span class="p" data-group-id="4075347333-3">}</span><span class="p" data-group-id="4075347333-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4075347333-10">[</span><span class="p" data-group-id="4075347333-11">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="4075347333-12">[</span><span class="p" data-group-id="4075347333-13">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4075347333-14">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4075347333-15">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="4075347333-15">]</span><span class="p" data-group-id="4075347333-14">}</span><span class="p" data-group-id="4075347333-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4075347333-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4075347333-17">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4075347333-18">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="4075347333-18">]</span><span class="p" data-group-id="4075347333-17">}</span><span class="p" data-group-id="4075347333-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4075347333-19">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="4075347333-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4075347333-20">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="4075347333-20">}</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="4075347333-12">]</span><span class="p" data-group-id="4075347333-11">}</span><span class="p" data-group-id="4075347333-10">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4075347333-1">}</span><span class="p">.</span></code></pre><p>As stated earlier, the order of the instructions is important. When upgrading,
│ │ │ │ +loaded when upgrading and deleted when downgrading:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1909657645-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="1909657645-2">[</span><span class="p" data-group-id="1909657645-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="1909657645-4">[</span><span class="p" data-group-id="1909657645-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1909657645-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1909657645-6">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1909657645-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1909657645-7">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1909657645-8">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1909657645-9">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1909657645-9">]</span><span class="p" data-group-id="1909657645-8">}</span><span class="p" data-group-id="1909657645-7">}</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="1909657645-4">]</span><span class="p" data-group-id="1909657645-3">}</span><span class="p" data-group-id="1909657645-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="1909657645-10">[</span><span class="p" data-group-id="1909657645-11">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="1909657645-12">[</span><span class="p" data-group-id="1909657645-13">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1909657645-14">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1909657645-15">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1909657645-15">]</span><span class="p" data-group-id="1909657645-14">}</span><span class="p" data-group-id="1909657645-13">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1909657645-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1909657645-17">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1909657645-18">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1909657645-18">]</span><span class="p" data-group-id="1909657645-17">}</span><span class="p" data-group-id="1909657645-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1909657645-19">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1909657645-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="1909657645-20">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1909657645-20">}</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="1909657645-12">]</span><span class="p" data-group-id="1909657645-11">}</span><span class="p" data-group-id="1909657645-10">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="1909657645-1">}</span><span class="p">.</span></code></pre><p>As stated earlier, the order of the instructions is important. When upgrading,
│ │ │ │  <code class="inline">m1</code> must be loaded, and the supervisor child specification changed, before the
│ │ │ │  new child process can be started. When downgrading, the child process must be
│ │ │ │  terminated before the child specification is changed and the module is deleted.</p><h2 id="adding-or-deleting-a-module" class="section-heading">
│ │ │ │    <a href="#adding-or-deleting-a-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Adding or Deleting a Module</span>
│ │ │ │  </h2>
│ │ │ │ -<p>_Example</p><p>_ A new functional module <code class="inline">m</code> is added to <code class="inline">ch_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7195214760-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7195214760-2">[</span><span class="p" data-group-id="7195214760-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7195214760-4">[</span><span class="p" data-group-id="7195214760-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="7195214760-5">}</span><span class="p" data-group-id="7195214760-4">]</span><span class="p" data-group-id="7195214760-3">}</span><span class="p" data-group-id="7195214760-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="7195214760-6">[</span><span class="p" data-group-id="7195214760-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7195214760-8">[</span><span class="p" data-group-id="7195214760-9">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="7195214760-9">}</span><span class="p" data-group-id="7195214760-8">]</span><span class="p" data-group-id="7195214760-7">}</span><span class="p" data-group-id="7195214760-6">]</span></code></pre><h2 id="starting-or-terminating-a-process" class="section-heading">
│ │ │ │ +<p>_Example</p><p>_ A new functional module <code class="inline">m</code> is added to <code class="inline">ch_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5763669230-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5763669230-2">[</span><span class="p" data-group-id="5763669230-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5763669230-4">[</span><span class="p" data-group-id="5763669230-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="5763669230-5">}</span><span class="p" data-group-id="5763669230-4">]</span><span class="p" data-group-id="5763669230-3">}</span><span class="p" data-group-id="5763669230-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5763669230-6">[</span><span class="p" data-group-id="5763669230-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5763669230-8">[</span><span class="p" data-group-id="5763669230-9">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="5763669230-9">}</span><span class="p" data-group-id="5763669230-8">]</span><span class="p" data-group-id="5763669230-7">}</span><span class="p" data-group-id="5763669230-6">]</span></code></pre><h2 id="starting-or-terminating-a-process" class="section-heading">
│ │ │ │    <a href="#starting-or-terminating-a-process" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting or Terminating a Process</span>
│ │ │ │  </h2>
│ │ │ │  <p>In a system structured according to the OTP design principles, any process would
│ │ │ │  be a child process belonging to a supervisor, see
│ │ │ │ @@ -274,29 +274,29 @@
│ │ │ │    <span class="text">Restarting an Application</span>
│ │ │ │  </h2>
│ │ │ │  <p>Restarting an application is useful when a change is too complicated to be made
│ │ │ │  without restarting the processes, for example, if the supervisor hierarchy has
│ │ │ │  been restructured.</p><p><em>Example</em></p><p>When adding a child <code class="inline">m1</code> to <code class="inline">ch_sup</code>, as in
│ │ │ │  <a href="appup_cookbook.xhtml#sup_add">Adding and Deleting Child Processes</a> in Changing a
│ │ │ │  Supervisor, an alternative to updating the supervisor is to restart the entire
│ │ │ │ -application:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2145911256-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2145911256-2">[</span><span class="p" data-group-id="2145911256-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2145911256-4">[</span><span class="p" data-group-id="2145911256-5">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="2145911256-5">}</span><span class="p" data-group-id="2145911256-4">]</span><span class="p" data-group-id="2145911256-3">}</span><span class="p" data-group-id="2145911256-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="2145911256-6">[</span><span class="p" data-group-id="2145911256-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2145911256-8">[</span><span class="p" data-group-id="2145911256-9">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="2145911256-9">}</span><span class="p" data-group-id="2145911256-8">]</span><span class="p" data-group-id="2145911256-7">}</span><span class="p" data-group-id="2145911256-6">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2145911256-1">}</span><span class="p">.</span></code></pre><p><a href="" id="app_spec"></a></p><h2 id="changing-an-application-specification" class="section-heading">
│ │ │ │ +application:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5295126922-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5295126922-2">[</span><span class="p" data-group-id="5295126922-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5295126922-4">[</span><span class="p" data-group-id="5295126922-5">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="5295126922-5">}</span><span class="p" data-group-id="5295126922-4">]</span><span class="p" data-group-id="5295126922-3">}</span><span class="p" data-group-id="5295126922-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5295126922-6">[</span><span class="p" data-group-id="5295126922-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5295126922-8">[</span><span class="p" data-group-id="5295126922-9">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="5295126922-9">}</span><span class="p" data-group-id="5295126922-8">]</span><span class="p" data-group-id="5295126922-7">}</span><span class="p" data-group-id="5295126922-6">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5295126922-1">}</span><span class="p">.</span></code></pre><p><a href="" id="app_spec"></a></p><h2 id="changing-an-application-specification" class="section-heading">
│ │ │ │    <a href="#changing-an-application-specification" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing an Application Specification</span>
│ │ │ │  </h2>
│ │ │ │  <p>When installing a release, the application specifications are automatically
│ │ │ │  updated before evaluating the <code class="inline">relup</code> script. Thus, no instructions are needed
│ │ │ │ -in the <code class="inline">.appup</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8775510182-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8775510182-2">[</span><span class="p" data-group-id="8775510182-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8775510182-4">[</span><span class="p" data-group-id="8775510182-4">]</span><span class="p" data-group-id="8775510182-3">}</span><span class="p" data-group-id="8775510182-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8775510182-5">[</span><span class="p" data-group-id="8775510182-6">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8775510182-7">[</span><span class="p" data-group-id="8775510182-7">]</span><span class="p" data-group-id="8775510182-6">}</span><span class="p" data-group-id="8775510182-5">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8775510182-1">}</span><span class="p">.</span></code></pre><h2 id="changing-application-configuration" class="section-heading">
│ │ │ │ +in the <code class="inline">.appup</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2085613874-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2085613874-2">[</span><span class="p" data-group-id="2085613874-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2085613874-4">[</span><span class="p" data-group-id="2085613874-4">]</span><span class="p" data-group-id="2085613874-3">}</span><span class="p" data-group-id="2085613874-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2085613874-5">[</span><span class="p" data-group-id="2085613874-6">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2085613874-7">[</span><span class="p" data-group-id="2085613874-7">]</span><span class="p" data-group-id="2085613874-6">}</span><span class="p" data-group-id="2085613874-5">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2085613874-1">}</span><span class="p">.</span></code></pre><h2 id="changing-application-configuration" class="section-heading">
│ │ │ │    <a href="#changing-application-configuration" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing Application Configuration</span>
│ │ │ │  </h2>
│ │ │ │  <p>Changing an application configuration by updating the <code class="inline">env</code> key in the <code class="inline">.app</code>
│ │ │ │  file is an instance of changing an application specification, see the previous
│ │ │ │ @@ -311,26 +311,26 @@
│ │ │ │  applications apply to primary applications only. There are no corresponding
│ │ │ │  instructions for included applications. However, since an included application
│ │ │ │  is really a supervision tree with a topmost supervisor, started as a child
│ │ │ │  process to a supervisor in the including application, a <code class="inline">.relup</code> file can be
│ │ │ │  manually created.</p><p><em>Example</em></p><p>Assume there is a release containing an application <code class="inline">prim_app</code>, which
│ │ │ │  have a supervisor <code class="inline">prim_sup</code> in its supervision tree.</p><p>In a new version of the release, the application <code class="inline">ch_app</code> is to be included in
│ │ │ │  <code class="inline">prim_app</code>. That is, its topmost supervisor <code class="inline">ch_sup</code> is to be started as a child
│ │ │ │ -process to <code class="inline">prim_sup</code>.</p><p>The workflow is as follows:</p><p><em>Step 1)</em> Edit the code for <code class="inline">prim_sup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="3207745234-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3207745234-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="3207745234-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3207745234-3">{</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="ss">supervisor</span><span class="w"> </span><span class="ss">flags</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -          </span><span class="p" data-group-id="3207745234-4">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -           </span><span class="p" data-group-id="3207745234-5">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3207745234-6">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="3207745234-7">[</span><span class="p" data-group-id="3207745234-7">]</span><span class="p" data-group-id="3207745234-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -            </span><span class="ss">permanent</span><span class="p">,</span><span class="ss">infinity</span><span class="p">,</span><span class="ss">supervisor</span><span class="p">,</span><span class="p" data-group-id="3207745234-8">[</span><span class="ss">ch_sup</span><span class="p" data-group-id="3207745234-8">]</span><span class="p" data-group-id="3207745234-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -           </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3207745234-4">]</span><span class="p" data-group-id="3207745234-3">}</span><span class="p" data-group-id="3207745234-2">}</span><span class="p">.</span></code></pre><p><em>Step 2)</em> Edit the <code class="inline">.app</code> file for <code class="inline">prim_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8630182066-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8630182066-2">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="8630182066-3">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="8630182066-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +process to <code class="inline">prim_sup</code>.</p><p>The workflow is as follows:</p><p><em>Step 1)</em> Edit the code for <code class="inline">prim_sup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0404237081-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0404237081-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0404237081-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0404237081-3">{</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="ss">supervisor</span><span class="w"> </span><span class="ss">flags</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ +          </span><span class="p" data-group-id="0404237081-4">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ +           </span><span class="p" data-group-id="0404237081-5">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0404237081-6">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="0404237081-7">[</span><span class="p" data-group-id="0404237081-7">]</span><span class="p" data-group-id="0404237081-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +            </span><span class="ss">permanent</span><span class="p">,</span><span class="ss">infinity</span><span class="p">,</span><span class="ss">supervisor</span><span class="p">,</span><span class="p" data-group-id="0404237081-8">[</span><span class="ss">ch_sup</span><span class="p" data-group-id="0404237081-8">]</span><span class="p" data-group-id="0404237081-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +           </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0404237081-4">]</span><span class="p" data-group-id="0404237081-3">}</span><span class="p" data-group-id="0404237081-2">}</span><span class="p">.</span></code></pre><p><em>Step 2)</em> Edit the <code class="inline">.app</code> file for <code class="inline">prim_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7063413429-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7063413429-2">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7063413429-3">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="7063413429-3">}</span><span class="p">,</span><span class="w">
│ │ │ │    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="8630182066-4">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8630182066-5">[</span><span class="ss">ch_app</span><span class="p" data-group-id="8630182066-5">]</span><span class="p" data-group-id="8630182066-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7063413429-4">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7063413429-5">[</span><span class="ss">ch_app</span><span class="p" data-group-id="7063413429-5">]</span><span class="p" data-group-id="7063413429-4">}</span><span class="p">,</span><span class="w">
│ │ │ │    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8630182066-2">]</span><span class="p" data-group-id="8630182066-1">}</span><span class="p">.</span></code></pre><p><em>Step 3)</em> Create a new <code class="inline">.rel</code> file, including <code class="inline">ch_app</code>:</p><pre><code class="text">{release,
│ │ │ │ + </span><span class="p" data-group-id="7063413429-2">]</span><span class="p" data-group-id="7063413429-1">}</span><span class="p">.</span></code></pre><p><em>Step 3)</em> Create a new <code class="inline">.rel</code> file, including <code class="inline">ch_app</code>:</p><pre><code class="text">{release,
│ │ │ │   ...,
│ │ │ │   [...,
│ │ │ │    {prim_app, &quot;2&quot;},
│ │ │ │    {ch_app, &quot;1&quot;}]}.</code></pre><p>The included application can be started in two ways. This is described in the
│ │ │ │  next two sections.</p><h3 id="application-restart" class="section-heading">
│ │ │ │    <a href="#application-restart" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │ @@ -385,74 +385,74 @@
│ │ │ │  <p><em>Step 4b)</em> Another way to start the included application (or stop it in the case
│ │ │ │  of downgrade) is by combining instructions for adding and removing child
│ │ │ │  processes to/from <code class="inline">prim_sup</code> with instructions for loading/unloading all
│ │ │ │  <code class="inline">ch_app</code> code and its application specification.</p><p>Again, the <code class="inline">.relup</code> file is created manually, either from scratch or by editing a
│ │ │ │  generated version. Load all code for <code class="inline">ch_app</code> first, and also load the
│ │ │ │  application specification, before <code class="inline">prim_sup</code> is updated. When downgrading,
│ │ │ │  <code class="inline">prim_sup</code> is to updated first, before the code for <code class="inline">ch_app</code> and its application
│ │ │ │ -specification are unloaded.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5180770419-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="5180770419-2">[</span><span class="p" data-group-id="5180770419-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="5180770419-4">[</span><span class="p" data-group-id="5180770419-4">]</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="5180770419-5">[</span><span class="p" data-group-id="5180770419-6">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="5180770419-7">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="5180770419-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="5180770419-8">]</span><span class="p" data-group-id="5180770419-7">}</span><span class="p" data-group-id="5180770419-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-9">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="5180770419-10">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="p" data-group-id="5180770419-11">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="5180770419-11">]</span><span class="p" data-group-id="5180770419-10">}</span><span class="p" data-group-id="5180770419-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +specification are unloaded.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2734876743-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2734876743-2">[</span><span class="p" data-group-id="2734876743-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="2734876743-4">[</span><span class="p" data-group-id="2734876743-4">]</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="2734876743-5">[</span><span class="p" data-group-id="2734876743-6">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="2734876743-7">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="2734876743-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="2734876743-8">]</span><span class="p" data-group-id="2734876743-7">}</span><span class="p" data-group-id="2734876743-6">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-9">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="2734876743-10">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="p" data-group-id="2734876743-11">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="2734876743-11">]</span><span class="p" data-group-id="2734876743-10">}</span><span class="p" data-group-id="2734876743-9">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">point_of_no_return</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-12">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="5180770419-13">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="5180770419-13">}</span><span class="p" data-group-id="5180770419-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-14">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="5180770419-15">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="5180770419-15">}</span><span class="p" data-group-id="5180770419-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="5180770419-17">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="5180770419-18">[</span><span class="ss">ch_app</span><span class="p" data-group-id="5180770419-18">]</span><span class="p" data-group-id="5180770419-17">}</span><span class="p" data-group-id="5180770419-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-19">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="5180770419-20">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="5180770419-20">]</span><span class="p" data-group-id="5180770419-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-21">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="5180770419-22">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="5180770419-22">}</span><span class="p" data-group-id="5180770419-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-23">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">up</span><span class="p">,</span><span class="p" data-group-id="5180770419-24">[</span><span class="p" data-group-id="5180770419-25">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="5180770419-26">[</span><span class="p" data-group-id="5180770419-26">]</span><span class="p" data-group-id="5180770419-25">}</span><span class="p" data-group-id="5180770419-24">]</span><span class="p" data-group-id="5180770419-23">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-27">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="5180770419-28">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="5180770419-28">]</span><span class="p" data-group-id="5180770419-27">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-29">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="5180770419-30">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">restart_child</span><span class="p">,</span><span class="p" data-group-id="5180770419-31">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="5180770419-31">]</span><span class="p" data-group-id="5180770419-30">}</span><span class="p" data-group-id="5180770419-29">}</span><span class="p" data-group-id="5180770419-5">]</span><span class="p" data-group-id="5180770419-3">}</span><span class="p" data-group-id="5180770419-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="5180770419-32">[</span><span class="p" data-group-id="5180770419-33">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="5180770419-34">[</span><span class="p" data-group-id="5180770419-34">]</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="5180770419-35">[</span><span class="p" data-group-id="5180770419-36">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="5180770419-37">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="5180770419-38">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="5180770419-38">]</span><span class="p" data-group-id="5180770419-37">}</span><span class="p" data-group-id="5180770419-36">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-12">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="2734876743-13">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="2734876743-13">}</span><span class="p" data-group-id="2734876743-12">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-14">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="2734876743-15">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="2734876743-15">}</span><span class="p" data-group-id="2734876743-14">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="2734876743-17">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="2734876743-18">[</span><span class="ss">ch_app</span><span class="p" data-group-id="2734876743-18">]</span><span class="p" data-group-id="2734876743-17">}</span><span class="p" data-group-id="2734876743-16">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-19">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="2734876743-20">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="2734876743-20">]</span><span class="p" data-group-id="2734876743-19">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-21">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="2734876743-22">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="2734876743-22">}</span><span class="p" data-group-id="2734876743-21">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-23">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">up</span><span class="p">,</span><span class="p" data-group-id="2734876743-24">[</span><span class="p" data-group-id="2734876743-25">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="2734876743-26">[</span><span class="p" data-group-id="2734876743-26">]</span><span class="p" data-group-id="2734876743-25">}</span><span class="p" data-group-id="2734876743-24">]</span><span class="p" data-group-id="2734876743-23">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-27">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="2734876743-28">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="2734876743-28">]</span><span class="p" data-group-id="2734876743-27">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-29">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="2734876743-30">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">restart_child</span><span class="p">,</span><span class="p" data-group-id="2734876743-31">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="2734876743-31">]</span><span class="p" data-group-id="2734876743-30">}</span><span class="p" data-group-id="2734876743-29">}</span><span class="p" data-group-id="2734876743-5">]</span><span class="p" data-group-id="2734876743-3">}</span><span class="p" data-group-id="2734876743-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="2734876743-32">[</span><span class="p" data-group-id="2734876743-33">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="2734876743-34">[</span><span class="p" data-group-id="2734876743-34">]</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="2734876743-35">[</span><span class="p" data-group-id="2734876743-36">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="2734876743-37">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="2734876743-38">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="2734876743-38">]</span><span class="p" data-group-id="2734876743-37">}</span><span class="p" data-group-id="2734876743-36">}</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="ss">point_of_no_return</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-39">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="5180770419-40">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">terminate_child</span><span class="p">,</span><span class="p" data-group-id="5180770419-41">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="5180770419-41">]</span><span class="p" data-group-id="5180770419-40">}</span><span class="p" data-group-id="5180770419-39">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-42">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="5180770419-43">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">delete_child</span><span class="p">,</span><span class="p" data-group-id="5180770419-44">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="5180770419-44">]</span><span class="p" data-group-id="5180770419-43">}</span><span class="p" data-group-id="5180770419-42">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-45">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="5180770419-46">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="5180770419-46">]</span><span class="p" data-group-id="5180770419-45">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-47">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="5180770419-48">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="5180770419-48">}</span><span class="p" data-group-id="5180770419-47">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-49">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">down</span><span class="p">,</span><span class="p" data-group-id="5180770419-50">[</span><span class="p" data-group-id="5180770419-51">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="5180770419-52">[</span><span class="p" data-group-id="5180770419-52">]</span><span class="p" data-group-id="5180770419-51">}</span><span class="p" data-group-id="5180770419-50">]</span><span class="p" data-group-id="5180770419-49">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-53">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="5180770419-54">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="5180770419-54">]</span><span class="p" data-group-id="5180770419-53">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-55">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="5180770419-56">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="5180770419-56">}</span><span class="p" data-group-id="5180770419-55">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-57">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="5180770419-58">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="5180770419-58">}</span><span class="p" data-group-id="5180770419-57">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-59">{</span><span class="ss">purge</span><span class="p">,</span><span class="p" data-group-id="5180770419-60">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="5180770419-60">]</span><span class="p" data-group-id="5180770419-59">}</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="5180770419-61">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="5180770419-62">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">unload</span><span class="p">,</span><span class="p" data-group-id="5180770419-63">[</span><span class="ss">ch_app</span><span class="p" data-group-id="5180770419-63">]</span><span class="p" data-group-id="5180770419-62">}</span><span class="p" data-group-id="5180770419-61">}</span><span class="p" data-group-id="5180770419-35">]</span><span class="p" data-group-id="5180770419-33">}</span><span class="p" data-group-id="5180770419-32">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="5180770419-1">}</span><span class="p">.</span></code></pre><h2 id="changing-non-erlang-code" class="section-heading">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-39">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="2734876743-40">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">terminate_child</span><span class="p">,</span><span class="p" data-group-id="2734876743-41">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="2734876743-41">]</span><span class="p" data-group-id="2734876743-40">}</span><span class="p" data-group-id="2734876743-39">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-42">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="2734876743-43">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">delete_child</span><span class="p">,</span><span class="p" data-group-id="2734876743-44">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="2734876743-44">]</span><span class="p" data-group-id="2734876743-43">}</span><span class="p" data-group-id="2734876743-42">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-45">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="2734876743-46">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="2734876743-46">]</span><span class="p" data-group-id="2734876743-45">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-47">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="2734876743-48">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="2734876743-48">}</span><span class="p" data-group-id="2734876743-47">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-49">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">down</span><span class="p">,</span><span class="p" data-group-id="2734876743-50">[</span><span class="p" data-group-id="2734876743-51">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="2734876743-52">[</span><span class="p" data-group-id="2734876743-52">]</span><span class="p" data-group-id="2734876743-51">}</span><span class="p" data-group-id="2734876743-50">]</span><span class="p" data-group-id="2734876743-49">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-53">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="2734876743-54">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="2734876743-54">]</span><span class="p" data-group-id="2734876743-53">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-55">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="2734876743-56">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="2734876743-56">}</span><span class="p" data-group-id="2734876743-55">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-57">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="2734876743-58">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="2734876743-58">}</span><span class="p" data-group-id="2734876743-57">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-59">{</span><span class="ss">purge</span><span class="p">,</span><span class="p" data-group-id="2734876743-60">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="2734876743-60">]</span><span class="p" data-group-id="2734876743-59">}</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="2734876743-61">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="2734876743-62">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">unload</span><span class="p">,</span><span class="p" data-group-id="2734876743-63">[</span><span class="ss">ch_app</span><span class="p" data-group-id="2734876743-63">]</span><span class="p" data-group-id="2734876743-62">}</span><span class="p" data-group-id="2734876743-61">}</span><span class="p" data-group-id="2734876743-35">]</span><span class="p" data-group-id="2734876743-33">}</span><span class="p" data-group-id="2734876743-32">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2734876743-1">}</span><span class="p">.</span></code></pre><h2 id="changing-non-erlang-code" class="section-heading">
│ │ │ │    <a href="#changing-non-erlang-code" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Changing Non-Erlang Code</span>
│ │ │ │  </h2>
│ │ │ │  <p>Changing code for a program written in another programming language than Erlang,
│ │ │ │  for example, a port program, is application-dependent and OTP provides no
│ │ │ │  special support.</p><p><em>Example</em></p><p>When changing code for a port program, assume that the Erlang process
│ │ │ │  controlling the port is a <code class="inline">gen_server</code> <code class="inline">portc</code> and that the port is opened in
│ │ │ │ -the callback function <code class="inline">init/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="2581048843-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2581048843-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +the callback function <code class="inline">init/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="5882570596-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5882570596-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="2581048843-2">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="2581048843-3">(</span><span class="n">App</span><span class="p" data-group-id="2581048843-3">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="2581048843-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="2581048843-4">(</span><span class="p" data-group-id="2581048843-5">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="2581048843-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2581048843-6">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2581048843-6">]</span><span class="p" data-group-id="2581048843-4">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="5882570596-2">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="5882570596-3">(</span><span class="n">App</span><span class="p" data-group-id="5882570596-3">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="5882570596-2">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="5882570596-4">(</span><span class="p" data-group-id="5882570596-5">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="5882570596-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5882570596-6">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5882570596-6">]</span><span class="p" data-group-id="5882570596-4">)</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="2581048843-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="2581048843-8">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2581048843-8">}</span><span class="p" data-group-id="2581048843-7">}</span><span class="p">.</span></code></pre><p>If the port program is to be updated, the code for the <code class="inline">gen_server</code> can be
│ │ │ │ +    </span><span class="p" data-group-id="5882570596-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="5882570596-8">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5882570596-8">}</span><span class="p" data-group-id="5882570596-7">}</span><span class="p">.</span></code></pre><p>If the port program is to be updated, the code for the <code class="inline">gen_server</code> can be
│ │ │ │  extended with a <code class="inline">code_change/3</code> function, which closes the old port and opens a
│ │ │ │  new port. (If necessary, the <code class="inline">gen_server</code> can first request data that must be
│ │ │ │ -saved from the port program and pass this data to the new port):</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="4688591120-1">(</span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="ss">port</span><span class="p" data-group-id="4688591120-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +saved from the port program and pass this data to the new port):</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="0344647789-1">(</span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="ss">port</span><span class="p" data-group-id="0344647789-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">close</span><span class="p">,</span><span class="w">
│ │ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ │ -        </span><span class="p" data-group-id="4688591120-2">{</span><span class="n">Port</span><span class="p">,</span><span class="ss">close</span><span class="p" data-group-id="4688591120-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +        </span><span class="p" data-group-id="0344647789-2">{</span><span class="n">Port</span><span class="p">,</span><span class="ss">close</span><span class="p" data-group-id="0344647789-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │              </span><span class="ss">true</span><span class="w">
│ │ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4688591120-3">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="4688591120-4">(</span><span class="n">App</span><span class="p" data-group-id="4688591120-4">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="4688591120-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="4688591120-5">(</span><span class="p" data-group-id="4688591120-6">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="4688591120-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4688591120-7">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4688591120-7">]</span><span class="p" data-group-id="4688591120-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ -    </span><span class="p" data-group-id="4688591120-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="4688591120-9">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4688591120-9">}</span><span class="p" data-group-id="4688591120-8">}</span><span class="p">.</span></code></pre><p>Update the application version number in the <code class="inline">.app</code> file and write an <code class="inline">.appup</code>
│ │ │ │ -file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8548260808-1">[</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8548260808-2">[</span><span class="p" data-group-id="8548260808-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8548260808-4">[</span><span class="p" data-group-id="8548260808-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8548260808-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="8548260808-6">}</span><span class="p" data-group-id="8548260808-5">}</span><span class="p" data-group-id="8548260808-4">]</span><span class="p" data-group-id="8548260808-3">}</span><span class="p" data-group-id="8548260808-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="8548260808-7">[</span><span class="p" data-group-id="8548260808-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8548260808-9">[</span><span class="p" data-group-id="8548260808-10">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8548260808-11">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="8548260808-11">}</span><span class="p" data-group-id="8548260808-10">}</span><span class="p" data-group-id="8548260808-9">]</span><span class="p" data-group-id="8548260808-8">}</span><span class="p" data-group-id="8548260808-7">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8548260808-1">]</span><span class="p">.</span></code></pre><p>Ensure that the <code class="inline">priv</code> directory, where the C program is located, is included in
│ │ │ │ -the new release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="4393063889-1">(</span><span class="s">&quot;my_release&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4393063889-2">[</span><span class="p" data-group-id="4393063889-3">{</span><span class="ss">dirs</span><span class="p">,</span><span class="p" data-group-id="4393063889-4">[</span><span class="ss">priv</span><span class="p" data-group-id="4393063889-4">]</span><span class="p" data-group-id="4393063889-3">}</span><span class="p" data-group-id="4393063889-2">]</span><span class="p" data-group-id="4393063889-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="0344647789-3">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="0344647789-4">(</span><span class="n">App</span><span class="p" data-group-id="0344647789-4">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="0344647789-3">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="0344647789-5">(</span><span class="p" data-group-id="0344647789-6">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="0344647789-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0344647789-7">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0344647789-7">]</span><span class="p" data-group-id="0344647789-5">)</span><span class="p">,</span><span class="w">
│ │ │ │ +    </span><span class="p" data-group-id="0344647789-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="0344647789-9">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0344647789-9">}</span><span class="p" data-group-id="0344647789-8">}</span><span class="p">.</span></code></pre><p>Update the application version number in the <code class="inline">.app</code> file and write an <code class="inline">.appup</code>
│ │ │ │ +file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9266564608-1">[</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9266564608-2">[</span><span class="p" data-group-id="9266564608-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9266564608-4">[</span><span class="p" data-group-id="9266564608-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9266564608-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="9266564608-6">}</span><span class="p" data-group-id="9266564608-5">}</span><span class="p" data-group-id="9266564608-4">]</span><span class="p" data-group-id="9266564608-3">}</span><span class="p" data-group-id="9266564608-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="9266564608-7">[</span><span class="p" data-group-id="9266564608-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9266564608-9">[</span><span class="p" data-group-id="9266564608-10">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9266564608-11">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="9266564608-11">}</span><span class="p" data-group-id="9266564608-10">}</span><span class="p" data-group-id="9266564608-9">]</span><span class="p" data-group-id="9266564608-8">}</span><span class="p" data-group-id="9266564608-7">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="9266564608-1">]</span><span class="p">.</span></code></pre><p>Ensure that the <code class="inline">priv</code> directory, where the C program is located, is included in
│ │ │ │ +the new release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="7113391618-1">(</span><span class="s">&quot;my_release&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7113391618-2">[</span><span class="p" data-group-id="7113391618-3">{</span><span class="ss">dirs</span><span class="p">,</span><span class="p" data-group-id="7113391618-4">[</span><span class="ss">priv</span><span class="p" data-group-id="7113391618-4">]</span><span class="p" data-group-id="7113391618-3">}</span><span class="p" data-group-id="7113391618-2">]</span><span class="p" data-group-id="7113391618-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="runtime-system-restart-and-upgrade" class="section-heading">
│ │ │ │    <a href="#runtime-system-restart-and-upgrade" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Runtime System Restart and Upgrade</span>
│ │ │ │  </h2>
│ │ │ │  <p>Two upgrade instructions restart the runtime system:</p><ul><li><p><code class="inline">restart_new_emulator</code></p><p>Intended when ERTS, Kernel, STDLIB, or SASL is upgraded. It is automatically
│ │ │ │ @@ -460,20 +460,20 @@
│ │ │ │  executed before all other upgrade instructions. For more information about
│ │ │ │  this instruction, see restart_new_emulator (Low-Level) in
│ │ │ │  <a href="release_handling.xhtml#restart_new_emulator_instr">Release Handling Instructions</a>.</p></li><li><p><code class="inline">restart_emulator</code></p><p>Used when a restart of the runtime system is required after all other upgrade
│ │ │ │  instructions are executed. For more information about this instruction, see
│ │ │ │  restart_emulator (Low-Level) in
│ │ │ │  <a href="release_handling.xhtml#restart_emulator_instr">Release Handling Instructions</a>.</p></li></ul><p>If a runtime system restart is necessary and no upgrade instructions are needed,
│ │ │ │  that is, if the restart itself is enough for the upgraded applications to start
│ │ │ │ -running the new versions, a simple <code class="inline">.relup</code> file can be created manually:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0131419745-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="0131419745-2">[</span><span class="p" data-group-id="0131419745-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="0131419745-4">[</span><span class="p" data-group-id="0131419745-4">]</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="0131419745-5">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="0131419745-5">]</span><span class="p" data-group-id="0131419745-3">}</span><span class="p" data-group-id="0131419745-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="0131419745-6">[</span><span class="p" data-group-id="0131419745-7">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="0131419745-8">[</span><span class="p" data-group-id="0131419745-8">]</span><span class="p">,</span><span class="w">
│ │ │ │ -   </span><span class="p" data-group-id="0131419745-9">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="0131419745-9">]</span><span class="p" data-group-id="0131419745-7">}</span><span class="p" data-group-id="0131419745-6">]</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0131419745-1">}</span><span class="p">.</span></code></pre><p>In this case, the release handler framework with automatic packing and unpacking
│ │ │ │ +running the new versions, a simple <code class="inline">.relup</code> file can be created manually:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0111340197-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="0111340197-2">[</span><span class="p" data-group-id="0111340197-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="0111340197-4">[</span><span class="p" data-group-id="0111340197-4">]</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="0111340197-5">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="0111340197-5">]</span><span class="p" data-group-id="0111340197-3">}</span><span class="p" data-group-id="0111340197-2">]</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="0111340197-6">[</span><span class="p" data-group-id="0111340197-7">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="0111340197-8">[</span><span class="p" data-group-id="0111340197-8">]</span><span class="p">,</span><span class="w">
│ │ │ │ +   </span><span class="p" data-group-id="0111340197-9">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="0111340197-9">]</span><span class="p" data-group-id="0111340197-7">}</span><span class="p" data-group-id="0111340197-6">]</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="0111340197-1">}</span><span class="p">.</span></code></pre><p>In this case, the release handler framework with automatic packing and unpacking
│ │ │ │  of release packages, automatic path updates, and so on, can be used without
│ │ │ │  having to specify <code class="inline">.appup</code> files.</p>
│ │ │ │  
│ │ │ │    </body>
│ │ │ │  </html>
│ │ │ ├── OEBPS/applications.xhtml
│ │ │ │ @@ -40,34 +40,34 @@
│ │ │ │  <a href="applications.xhtml#app_dir">directory structure</a>.</p><p><a href="" id="callback_module"></a></p><h2 id="application-callback-module" class="section-heading">
│ │ │ │    <a href="#application-callback-module" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Application Callback Module</span>
│ │ │ │  </h2>
│ │ │ │  <p>How to start and stop the code for the application, including its supervision
│ │ │ │ -tree, is described by two callback functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start</span><span class="p" data-group-id="6427505045-1">(</span><span class="n">StartType</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="6427505045-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6427505045-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="6427505045-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="6427505045-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6427505045-3">}</span><span class="w">
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="6427505045-4">(</span><span class="n">State</span><span class="p" data-group-id="6427505045-4">)</span></code></pre><ul><li><code class="inline">start/2</code> is called when starting the application and is to create the
│ │ │ │ +tree, is described by two callback functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start</span><span class="p" data-group-id="1358008847-1">(</span><span class="n">StartType</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="1358008847-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1358008847-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="1358008847-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="1358008847-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1358008847-3">}</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="1358008847-4">(</span><span class="n">State</span><span class="p" data-group-id="1358008847-4">)</span></code></pre><ul><li><code class="inline">start/2</code> is called when starting the application and is to create the
│ │ │ │  supervision tree by starting the top supervisor. It is expected to return the
│ │ │ │  pid of the top supervisor and an optional term, <code class="inline">State</code>, which defaults to
│ │ │ │  <code class="inline">[]</code>. This term is passed as is to <code class="inline">stop/1</code>.</li><li><code class="inline">StartType</code> is usually the atom <code class="inline">normal</code>. It has other values only in the case
│ │ │ │  of a takeover or failover; see
│ │ │ │  <a href="distributed_applications.xhtml">Distributed Applications</a>.</li><li><code class="inline">StartArgs</code> is defined by the key <code class="inline">mod</code> in the
│ │ │ │  <a href="applications.xhtml#appl_res_file">application resource file</a>.</li><li><code class="inline">stop/1</code> is called <em>after</em> the application has been stopped and is to do any
│ │ │ │  necessary cleaning up. The actual stopping of the application, that is,
│ │ │ │  shutting down the supervision tree, is handled automatically as described in
│ │ │ │  <a href="applications.xhtml#stopping">Starting and Stopping Applications</a>.</li></ul><p><a href="" id="ch_app"></a></p><p>Example of an application callback module for packaging the supervision tree
│ │ │ │ -from <a href="sup_princ.xhtml#ex">Supervisor Behaviour</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4712763136-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="4712763136-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="4712763136-2">(</span><span class="ss">application</span><span class="p" data-group-id="4712763136-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +from <a href="sup_princ.xhtml#ex">Supervisor Behaviour</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0660386370-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="0660386370-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="0660386370-2">(</span><span class="ss">application</span><span class="p" data-group-id="0660386370-2">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="w">
│ │ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4712763136-3">(</span><span class="p" data-group-id="4712763136-4">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4712763136-4">]</span><span class="p" data-group-id="4712763136-3">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0660386370-3">(</span><span class="p" data-group-id="0660386370-4">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0660386370-4">]</span><span class="p" data-group-id="0660386370-3">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="4712763136-5">(</span><span class="p">_</span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="4712763136-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ -    </span><span class="nc">ch_sup</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="4712763136-6">(</span><span class="p" data-group-id="4712763136-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="0660386370-5">(</span><span class="p">_</span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="0660386370-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +    </span><span class="nc">ch_sup</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0660386370-6">(</span><span class="p" data-group-id="0660386370-6">)</span><span class="p">.</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="4712763136-7">(</span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="4712763136-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="0660386370-7">(</span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="0660386370-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>A library application that cannot be started or stopped does not need any
│ │ │ │  application callback module.</p><p><a href="" id="appl_res_file"></a></p><h2 id="application-resource-file" class="section-heading">
│ │ │ │    <a href="#application-resource-file" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Application Resource File</span>
│ │ │ │  </h2>
│ │ │ │ @@ -78,22 +78,22 @@
│ │ │ │  keys.</li></ul><p>The contents of a minimal <code class="inline">.app</code> file for a library application <code class="inline">libapp</code> looks
│ │ │ │  as follows:</p><pre><code class="text">{application, libapp, []}.</code></pre><p>The contents of a minimal <code class="inline">.app</code> file <code class="inline">ch_app.app</code> for a supervision tree
│ │ │ │  application like <code class="inline">ch_app</code> looks as follows:</p><pre><code class="text">{application, ch_app,
│ │ │ │   [{mod, {ch_app,[]}}]}.</code></pre><p>The key <code class="inline">mod</code> defines the callback module and start argument of the application,
│ │ │ │  in this case <code class="inline">ch_app</code> and <code class="inline">[]</code>, respectively. This means that the following is
│ │ │ │  called when the application is to be started:</p><pre><code class="text">ch_app:start(normal, [])</code></pre><p>The following is called when the application is stopped:</p><pre><code class="text">ch_app:stop([])</code></pre><p>When using <a href="../../../lib/sasl/doc/html/systools.html"><code class="inline">systools</code></a>, the Erlang/OTP tools for packaging code (see Section
│ │ │ │  <a href="release_structure.xhtml">Releases</a>), the keys <code class="inline">description</code>, <code class="inline">vsn</code>, <code class="inline">modules</code>,
│ │ │ │ -<code class="inline">registered</code>, and <code class="inline">applications</code> are also to be specified:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1440117116-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1440117116-2">[</span><span class="p" data-group-id="1440117116-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="1440117116-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1440117116-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="1440117116-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1440117116-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1440117116-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1440117116-6">]</span><span class="p" data-group-id="1440117116-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1440117116-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1440117116-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="1440117116-8">]</span><span class="p" data-group-id="1440117116-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1440117116-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1440117116-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="1440117116-10">]</span><span class="p" data-group-id="1440117116-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="1440117116-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1440117116-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="1440117116-13">[</span><span class="p" data-group-id="1440117116-13">]</span><span class="p" data-group-id="1440117116-12">}</span><span class="p" data-group-id="1440117116-11">}</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1440117116-2">]</span><span class="p" data-group-id="1440117116-1">}</span><span class="p">.</span></code></pre><ul><li><code class="inline">description</code> - A short description, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">vsn</code> - Version number, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">modules</code> - All modules <em>introduced</em> by this application. <a href="../../../lib/sasl/doc/html/systools.html"><code class="inline">systools</code></a> uses
│ │ │ │ +<code class="inline">registered</code>, and <code class="inline">applications</code> are also to be specified:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7263533821-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7263533821-2">[</span><span class="p" data-group-id="7263533821-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="7263533821-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7263533821-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="7263533821-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7263533821-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7263533821-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="7263533821-6">]</span><span class="p" data-group-id="7263533821-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7263533821-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7263533821-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="7263533821-8">]</span><span class="p" data-group-id="7263533821-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7263533821-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7263533821-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="7263533821-10">]</span><span class="p" data-group-id="7263533821-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="7263533821-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7263533821-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="7263533821-13">[</span><span class="p" data-group-id="7263533821-13">]</span><span class="p" data-group-id="7263533821-12">}</span><span class="p" data-group-id="7263533821-11">}</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7263533821-2">]</span><span class="p" data-group-id="7263533821-1">}</span><span class="p">.</span></code></pre><ul><li><code class="inline">description</code> - A short description, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">vsn</code> - Version number, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">modules</code> - All modules <em>introduced</em> by this application. <a href="../../../lib/sasl/doc/html/systools.html"><code class="inline">systools</code></a> uses
│ │ │ │  this list when generating boot scripts and tar files. A module must only
│ │ │ │  be included in one application. Defaults to <code class="inline">[]</code>.</li><li><code class="inline">registered</code> - All names of registered processes in the application.
│ │ │ │  <a href="../../../lib/sasl/doc/html/systools.html"><code class="inline">systools</code></a> uses this list to detect name clashes between applications.
│ │ │ │  Defaults to <code class="inline">[]</code>.</li><li><code class="inline">applications</code> - All applications that must be started before this
│ │ │ │  application is started. <a href="../../../lib/sasl/doc/html/systools.html"><code class="inline">systools</code></a> uses this list to generate correct boot
│ │ │ │  scripts. Defaults to <code class="inline">[]</code>. Notice that all applications have dependencies to
│ │ │ │  at least Kernel and STDLIB.</li></ul><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>For details about the syntax and contents of the application resource file,
│ │ │ │ @@ -205,38 +205,38 @@
│ │ │ │  stop applications.</p><h2 id="loading-and-unloading-applications" class="section-heading">
│ │ │ │    <a href="#loading-and-unloading-applications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Loading and Unloading Applications</span>
│ │ │ │  </h2>
│ │ │ │  <p>Before an application can be started, it must be <em>loaded</em>. The application
│ │ │ │ -controller reads and stores the information from the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">load</span><span class="p" data-group-id="0884524063-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="0884524063-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +controller reads and stores the information from the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">load</span><span class="p" data-group-id="7728606049-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="7728606049-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="0884524063-2">(</span><span class="p" data-group-id="0884524063-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0884524063-3">[</span><span class="p" data-group-id="0884524063-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="0884524063-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="0884524063-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="0884524063-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="0884524063-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="0884524063-6">}</span><span class="p" data-group-id="0884524063-3">]</span></code></pre><p>An application that has been stopped, or has never been started, can be
│ │ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="7728606049-2">(</span><span class="p" data-group-id="7728606049-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7728606049-3">[</span><span class="p" data-group-id="7728606049-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="7728606049-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7728606049-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="7728606049-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="7728606049-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="7728606049-6">}</span><span class="p" data-group-id="7728606049-3">]</span></code></pre><p>An application that has been stopped, or has never been started, can be
│ │ │ │  unloaded. The information about the application is erased from the internal
│ │ │ │ -database of the application controller.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">unload</span><span class="p" data-group-id="1356447276-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="1356447276-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +database of the application controller.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">unload</span><span class="p" data-group-id="8223070572-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="8223070572-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -4&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="1356447276-2">(</span><span class="p" data-group-id="1356447276-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="1356447276-3">[</span><span class="p" data-group-id="1356447276-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="1356447276-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="1356447276-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="1356447276-5">}</span><span class="p" data-group-id="1356447276-3">]</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Loading/unloading an application does not load/unload the code used by the
│ │ │ │ +4&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="8223070572-2">(</span><span class="p" data-group-id="8223070572-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="8223070572-3">[</span><span class="p" data-group-id="8223070572-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="8223070572-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="8223070572-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="8223070572-5">}</span><span class="p" data-group-id="8223070572-3">]</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Loading/unloading an application does not load/unload the code used by the
│ │ │ │  application. Code loading is handled in the usual way by the code server.</p></section><p><a href="" id="stopping"></a></p><h2 id="starting-and-stopping-applications" class="section-heading">
│ │ │ │    <a href="#starting-and-stopping-applications" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Starting and Stopping Applications</span>
│ │ │ │  </h2>
│ │ │ │ -<p>An application is started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4330632429-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="4330632429-1">)</span><span class="p">.</span><span class="w">
│ │ │ │ +<p>An application is started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5289982031-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="5289982031-1">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -6&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">which_applications</span><span class="p" data-group-id="4330632429-2">(</span><span class="p" data-group-id="4330632429-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="4330632429-3">[</span><span class="p" data-group-id="4330632429-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="4330632429-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4330632429-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="4330632429-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4330632429-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4330632429-6">}</span><span class="p" data-group-id="4330632429-3">]</span></code></pre><p>If the application is not already loaded, the application controller first loads
│ │ │ │ +6&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">which_applications</span><span class="p" data-group-id="5289982031-2">(</span><span class="p" data-group-id="5289982031-2">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="5289982031-3">[</span><span class="p" data-group-id="5289982031-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="5289982031-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5289982031-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="5289982031-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="5289982031-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="5289982031-6">}</span><span class="p" data-group-id="5289982031-3">]</span></code></pre><p>If the application is not already loaded, the application controller first loads
│ │ │ │  it using <a href="../../../lib/kernel/doc/html/application.html#load/1"><code class="inline">application:load/1</code></a>. It checks the value of the <code class="inline">applications</code> key to
│ │ │ │  ensure that all applications that are to be started before this application are
│ │ │ │  running.</p><p><a href="" id="application_master"></a></p><p>Following that, the application controller creates an <em>application master</em> for
│ │ │ │  the application.</p><p>The application master establishes itself as the <a href="../../../lib/../erts/doc/html/erlang.html#group_leader/0">group
│ │ │ │  leader</a> of all processes in the application
│ │ │ │  and will forward I/O to the previous group leader.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The purpose of the application master being the group leader is to easily
│ │ │ │  keep track of which processes that belong to the application. That is needed
│ │ │ │ @@ -252,55 +252,55 @@
│ │ │ │  defined by the <code class="inline">mod</code> key.</p><h2 id="configuring-an-application" class="section-heading">
│ │ │ │    <a href="#configuring-an-application" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Configuring an Application</span>
│ │ │ │  </h2>
│ │ │ │  <p>An application can be configured using <em>configuration parameters</em>. These are a
│ │ │ │ -list of <code class="inline">{Par,Val}</code> tuples specified by a key <code class="inline">env</code> in the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4364467928-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4364467928-2">[</span><span class="p" data-group-id="4364467928-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="4364467928-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4364467928-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4364467928-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4364467928-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4364467928-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="4364467928-6">]</span><span class="p" data-group-id="4364467928-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4364467928-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4364467928-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="4364467928-8">]</span><span class="p" data-group-id="4364467928-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4364467928-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4364467928-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="4364467928-10">]</span><span class="p" data-group-id="4364467928-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4364467928-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4364467928-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="4364467928-13">[</span><span class="p" data-group-id="4364467928-13">]</span><span class="p" data-group-id="4364467928-12">}</span><span class="p" data-group-id="4364467928-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ -  </span><span class="p" data-group-id="4364467928-14">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4364467928-15">[</span><span class="p" data-group-id="4364467928-16">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="4364467928-16">}</span><span class="p" data-group-id="4364467928-15">]</span><span class="p" data-group-id="4364467928-14">}</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="4364467928-2">]</span><span class="p" data-group-id="4364467928-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Par</code> is to be an atom. <code class="inline">Val</code> is any term. The application can retrieve the
│ │ │ │ +list of <code class="inline">{Par,Val}</code> tuples specified by a key <code class="inline">env</code> in the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4798217125-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4798217125-2">[</span><span class="p" data-group-id="4798217125-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="4798217125-3">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4798217125-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4798217125-4">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4798217125-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4798217125-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="4798217125-6">]</span><span class="p" data-group-id="4798217125-5">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4798217125-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4798217125-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="4798217125-8">]</span><span class="p" data-group-id="4798217125-7">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4798217125-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4798217125-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="4798217125-10">]</span><span class="p" data-group-id="4798217125-9">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4798217125-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4798217125-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="4798217125-13">[</span><span class="p" data-group-id="4798217125-13">]</span><span class="p" data-group-id="4798217125-12">}</span><span class="p" data-group-id="4798217125-11">}</span><span class="p">,</span><span class="w">
│ │ │ │ +  </span><span class="p" data-group-id="4798217125-14">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4798217125-15">[</span><span class="p" data-group-id="4798217125-16">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="4798217125-16">}</span><span class="p" data-group-id="4798217125-15">]</span><span class="p" data-group-id="4798217125-14">}</span><span class="w">
│ │ │ │ + </span><span class="p" data-group-id="4798217125-2">]</span><span class="p" data-group-id="4798217125-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Par</code> is to be an atom. <code class="inline">Val</code> is any term. The application can retrieve the
│ │ │ │  value of a configuration parameter by calling <code class="inline">application:get_env(App, Par)</code> or
│ │ │ │  a number of similar functions. For more information, see module <a href="../../../lib/kernel/doc/html/application.html"><code class="inline">application</code></a>
│ │ │ │  in Kernel.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="2568657917-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="2568657917-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="2568657917-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="2568657917-2">]</span><span class="w"> </span><span class="p" data-group-id="2568657917-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="2568657917-3">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="7120351355-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="7120351355-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="7120351355-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="7120351355-2">]</span><span class="w"> </span><span class="p" data-group-id="7120351355-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="7120351355-3">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="2568657917-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="2568657917-4">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2568657917-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="2568657917-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="7120351355-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="7120351355-4">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7120351355-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="7120351355-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="2568657917-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="2568657917-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="2568657917-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="2568657917-7">}</span></code></pre><p>The values in the <code class="inline">.app</code> file can be overridden by values in a <em>system
│ │ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="7120351355-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="7120351355-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7120351355-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="7120351355-7">}</span></code></pre><p>The values in the <code class="inline">.app</code> file can be overridden by values in a <em>system
│ │ │ │  configuration file</em>. This is a file that contains configuration parameters for
│ │ │ │ -relevant applications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9337404175-1">[</span><span class="p" data-group-id="9337404175-2">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9337404175-3">[</span><span class="p" data-group-id="9337404175-4">{</span><span class="n">Par11</span><span class="p">,</span><span class="n">Val11</span><span class="p" data-group-id="9337404175-4">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9337404175-3">]</span><span class="p" data-group-id="9337404175-2">}</span><span class="p">,</span><span class="w">
│ │ │ │ +relevant applications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2213171255-1">[</span><span class="p" data-group-id="2213171255-2">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2213171255-3">[</span><span class="p" data-group-id="2213171255-4">{</span><span class="n">Par11</span><span class="p">,</span><span class="n">Val11</span><span class="p" data-group-id="2213171255-4">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2213171255-3">]</span><span class="p" data-group-id="2213171255-2">}</span><span class="p">,</span><span class="w">
│ │ │ │   </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ │ - </span><span class="p" data-group-id="9337404175-5">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9337404175-6">[</span><span class="p" data-group-id="9337404175-7">{</span><span class="n">ParN1</span><span class="p">,</span><span class="n">ValN1</span><span class="p" data-group-id="9337404175-7">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9337404175-6">]</span><span class="p" data-group-id="9337404175-5">}</span><span class="p" data-group-id="9337404175-1">]</span><span class="p">.</span></code></pre><p>The system configuration is to be called <code class="inline">Name.config</code> and Erlang is to be
│ │ │ │ + </span><span class="p" data-group-id="2213171255-5">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2213171255-6">[</span><span class="p" data-group-id="2213171255-7">{</span><span class="n">ParN1</span><span class="p">,</span><span class="n">ValN1</span><span class="p" data-group-id="2213171255-7">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2213171255-6">]</span><span class="p" data-group-id="2213171255-5">}</span><span class="p" data-group-id="2213171255-1">]</span><span class="p">.</span></code></pre><p>The system configuration is to be called <code class="inline">Name.config</code> and Erlang is to be
│ │ │ │  started with the command-line argument <code class="inline">-config Name</code>. For details, see
│ │ │ │  <a href="../../../lib/kernel/doc/html/config.xhtml"><code class="inline">config</code></a> in Kernel.</p><p><em>Example:</em></p><p>A file <code class="inline">test.config</code> is created with the following contents:</p><pre><code class="text">[{ch_app, [{file, &quot;testlog&quot;}]}].</code></pre><p>The value of <code class="inline">file</code> overrides the value of <code class="inline">file</code> as defined in the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -config test</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="0101577209-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="0101577209-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="0101577209-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="0101577209-2">]</span><span class="w"> </span><span class="p" data-group-id="0101577209-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="0101577209-3">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="2476940352-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="2476940352-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="2476940352-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="2476940352-2">]</span><span class="w"> </span><span class="p" data-group-id="2476940352-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="2476940352-3">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="0101577209-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="0101577209-4">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="0101577209-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="0101577209-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="2476940352-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="2476940352-4">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2476940352-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="2476940352-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="0101577209-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="0101577209-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="0101577209-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="0101577209-7">}</span></code></pre><p>If <a href="release_handling.xhtml#sys">release handling</a> is used, exactly one system
│ │ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="2476940352-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="2476940352-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="2476940352-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="2476940352-7">}</span></code></pre><p>If <a href="release_handling.xhtml#sys">release handling</a> is used, exactly one system
│ │ │ │  configuration file is to be used and that file is to be called <code class="inline">sys.config</code>.</p><p>The values in the <code class="inline">.app</code> file and the values in a system configuration file can
│ │ │ │  be overridden directly from the command line:</p><pre><code class="text">% erl -ApplName Par1 Val1 ... ParN ValN</code></pre><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -ch_app file &#39;&quot;testlog&quot;&#39;</span><span class="w">
│ │ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="8964833708-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="8964833708-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="8964833708-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="8964833708-2">]</span><span class="w"> </span><span class="p" data-group-id="8964833708-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="8964833708-3">]</span><span class="w">
│ │ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="7190268388-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="7190268388-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="7190268388-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="7190268388-2">]</span><span class="w"> </span><span class="p" data-group-id="7190268388-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="7190268388-3">]</span><span class="w">
│ │ │ │  
│ │ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="8964833708-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="8964833708-4">)</span><span class="gp unselectable">
│ │ │ │ -1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="8964833708-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="8964833708-5">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="7190268388-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="7190268388-4">)</span><span class="gp unselectable">
│ │ │ │ +1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7190268388-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="7190268388-5">)</span><span class="p">.</span><span class="w">
│ │ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="8964833708-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="8964833708-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ -</span><span class="p" data-group-id="8964833708-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="8964833708-7">}</span></code></pre><h2 id="application-start-types" class="section-heading">
│ │ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="7190268388-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="7190268388-6">)</span><span class="p">.</span><span class="w">
│ │ │ │ +</span><span class="p" data-group-id="7190268388-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="7190268388-7">}</span></code></pre><h2 id="application-start-types" class="section-heading">
│ │ │ │    <a href="#application-start-types" class="hover-link">
│ │ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ │    </a>
│ │ │ │    <span class="text">Application Start Types</span>
│ │ │ │  </h2>
│ │ │ │  <p>A <em>start type</em> is defined when starting the application:</p><pre><code class="text">application:start(Application, Type)</code></pre><p><code class="inline">application:start(Application)</code> is the same as calling
│ │ │ │  <code class="inline">application:start(Application, temporary)</code>. The type can also be <code class="inline">permanent</code> or
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/applications.html
│ │ │ @@ -135,34 +135,34 @@
│ │ │  <a href="applications.html#app_dir">directory structure</a>.</p><p><a href="" id="callback_module"></a></p><h2 id="application-callback-module" class="section-heading">
│ │ │    <a href="#application-callback-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Application Callback Module</span>
│ │ │  </h2>
│ │ │  <p>How to start and stop the code for the application, including its supervision
│ │ │ -tree, is described by two callback functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start</span><span class="p" data-group-id="7374342298-1">(</span><span class="n">StartType</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="7374342298-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7374342298-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="7374342298-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="7374342298-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7374342298-3">}</span><span class="w">
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="7374342298-4">(</span><span class="n">State</span><span class="p" data-group-id="7374342298-4">)</span></code></pre><ul><li><code class="inline">start/2</code> is called when starting the application and is to create the
│ │ │ +tree, is described by two callback functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start</span><span class="p" data-group-id="7224318367-1">(</span><span class="n">StartType</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="7224318367-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7224318367-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="7224318367-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="7224318367-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7224318367-3">}</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="7224318367-4">(</span><span class="n">State</span><span class="p" data-group-id="7224318367-4">)</span></code></pre><ul><li><code class="inline">start/2</code> is called when starting the application and is to create the
│ │ │  supervision tree by starting the top supervisor. It is expected to return the
│ │ │  pid of the top supervisor and an optional term, <code class="inline">State</code>, which defaults to
│ │ │  <code class="inline">[]</code>. This term is passed as is to <code class="inline">stop/1</code>.</li><li><code class="inline">StartType</code> is usually the atom <code class="inline">normal</code>. It has other values only in the case
│ │ │  of a takeover or failover; see
│ │ │  <a href="distributed_applications.html">Distributed Applications</a>.</li><li><code class="inline">StartArgs</code> is defined by the key <code class="inline">mod</code> in the
│ │ │  <a href="applications.html#appl_res_file">application resource file</a>.</li><li><code class="inline">stop/1</code> is called <em>after</em> the application has been stopped and is to do any
│ │ │  necessary cleaning up. The actual stopping of the application, that is,
│ │ │  shutting down the supervision tree, is handled automatically as described in
│ │ │  <a href="applications.html#stopping">Starting and Stopping Applications</a>.</li></ul><p><a href="" id="ch_app"></a></p><p>Example of an application callback module for packaging the supervision tree
│ │ │ -from <a href="sup_princ.html#ex">Supervisor Behaviour</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5245116288-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="5245116288-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5245116288-2">(</span><span class="ss">application</span><span class="p" data-group-id="5245116288-2">)</span><span class="p">.</span><span class="w">
│ │ │ +from <a href="sup_princ.html#ex">Supervisor Behaviour</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9530833128-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="9530833128-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9530833128-2">(</span><span class="ss">application</span><span class="p" data-group-id="9530833128-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5245116288-3">(</span><span class="p" data-group-id="5245116288-4">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5245116288-4">]</span><span class="p" data-group-id="5245116288-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9530833128-3">(</span><span class="p" data-group-id="9530833128-4">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9530833128-4">]</span><span class="p" data-group-id="9530833128-3">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="5245116288-5">(</span><span class="p">_</span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="5245116288-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">ch_sup</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5245116288-6">(</span><span class="p" data-group-id="5245116288-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="9530833128-5">(</span><span class="p">_</span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="9530833128-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">ch_sup</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9530833128-6">(</span><span class="p" data-group-id="9530833128-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="5245116288-7">(</span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="5245116288-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="9530833128-7">(</span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="9530833128-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>A library application that cannot be started or stopped does not need any
│ │ │  application callback module.</p><p><a href="" id="appl_res_file"></a></p><h2 id="application-resource-file" class="section-heading">
│ │ │    <a href="#application-resource-file" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Application Resource File</span>
│ │ │  </h2>
│ │ │ @@ -173,22 +173,22 @@
│ │ │  keys.</li></ul><p>The contents of a minimal <code class="inline">.app</code> file for a library application <code class="inline">libapp</code> looks
│ │ │  as follows:</p><pre><code class="text">{application, libapp, []}.</code></pre><p>The contents of a minimal <code class="inline">.app</code> file <code class="inline">ch_app.app</code> for a supervision tree
│ │ │  application like <code class="inline">ch_app</code> looks as follows:</p><pre><code class="text">{application, ch_app,
│ │ │   [{mod, {ch_app,[]}}]}.</code></pre><p>The key <code class="inline">mod</code> defines the callback module and start argument of the application,
│ │ │  in this case <code class="inline">ch_app</code> and <code class="inline">[]</code>, respectively. This means that the following is
│ │ │  called when the application is to be started:</p><pre><code class="text">ch_app:start(normal, [])</code></pre><p>The following is called when the application is stopped:</p><pre><code class="text">ch_app:stop([])</code></pre><p>When using <a href="../../lib/sasl-4.2.2/doc/html/systools.html"><code class="inline">systools</code></a>, the Erlang/OTP tools for packaging code (see Section
│ │ │  <a href="release_structure.html">Releases</a>), the keys <code class="inline">description</code>, <code class="inline">vsn</code>, <code class="inline">modules</code>,
│ │ │ -<code class="inline">registered</code>, and <code class="inline">applications</code> are also to be specified:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8387730487-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8387730487-2">[</span><span class="p" data-group-id="8387730487-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="8387730487-3">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8387730487-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="8387730487-4">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8387730487-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8387730487-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8387730487-6">]</span><span class="p" data-group-id="8387730487-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8387730487-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8387730487-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="8387730487-8">]</span><span class="p" data-group-id="8387730487-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8387730487-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8387730487-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="8387730487-10">]</span><span class="p" data-group-id="8387730487-9">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8387730487-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8387730487-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="8387730487-13">[</span><span class="p" data-group-id="8387730487-13">]</span><span class="p" data-group-id="8387730487-12">}</span><span class="p" data-group-id="8387730487-11">}</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8387730487-2">]</span><span class="p" data-group-id="8387730487-1">}</span><span class="p">.</span></code></pre><ul><li><code class="inline">description</code> - A short description, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">vsn</code> - Version number, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">modules</code> - All modules <em>introduced</em> by this application. <a href="../../lib/sasl-4.2.2/doc/html/systools.html"><code class="inline">systools</code></a> uses
│ │ │ +<code class="inline">registered</code>, and <code class="inline">applications</code> are also to be specified:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3719279159-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3719279159-2">[</span><span class="p" data-group-id="3719279159-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="3719279159-3">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3719279159-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="3719279159-4">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3719279159-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3719279159-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3719279159-6">]</span><span class="p" data-group-id="3719279159-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3719279159-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3719279159-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="3719279159-8">]</span><span class="p" data-group-id="3719279159-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3719279159-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3719279159-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="3719279159-10">]</span><span class="p" data-group-id="3719279159-9">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3719279159-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3719279159-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="3719279159-13">[</span><span class="p" data-group-id="3719279159-13">]</span><span class="p" data-group-id="3719279159-12">}</span><span class="p" data-group-id="3719279159-11">}</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3719279159-2">]</span><span class="p" data-group-id="3719279159-1">}</span><span class="p">.</span></code></pre><ul><li><code class="inline">description</code> - A short description, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">vsn</code> - Version number, a string. Defaults to <code class="inline">&quot;&quot;</code>.</li><li><code class="inline">modules</code> - All modules <em>introduced</em> by this application. <a href="../../lib/sasl-4.2.2/doc/html/systools.html"><code class="inline">systools</code></a> uses
│ │ │  this list when generating boot scripts and tar files. A module must only
│ │ │  be included in one application. Defaults to <code class="inline">[]</code>.</li><li><code class="inline">registered</code> - All names of registered processes in the application.
│ │ │  <a href="../../lib/sasl-4.2.2/doc/html/systools.html"><code class="inline">systools</code></a> uses this list to detect name clashes between applications.
│ │ │  Defaults to <code class="inline">[]</code>.</li><li><code class="inline">applications</code> - All applications that must be started before this
│ │ │  application is started. <a href="../../lib/sasl-4.2.2/doc/html/systools.html"><code class="inline">systools</code></a> uses this list to generate correct boot
│ │ │  scripts. Defaults to <code class="inline">[]</code>. Notice that all applications have dependencies to
│ │ │  at least Kernel and STDLIB.</li></ul><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>For details about the syntax and contents of the application resource file,
│ │ │ @@ -300,38 +300,38 @@
│ │ │  stop applications.</p><h2 id="loading-and-unloading-applications" class="section-heading">
│ │ │    <a href="#loading-and-unloading-applications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Loading and Unloading Applications</span>
│ │ │  </h2>
│ │ │  <p>Before an application can be started, it must be <em>loaded</em>. The application
│ │ │ -controller reads and stores the information from the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">load</span><span class="p" data-group-id="5098402812-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="5098402812-1">)</span><span class="p">.</span><span class="w">
│ │ │ +controller reads and stores the information from the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">load</span><span class="p" data-group-id="9409471235-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="9409471235-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="5098402812-2">(</span><span class="p" data-group-id="5098402812-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5098402812-3">[</span><span class="p" data-group-id="5098402812-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="5098402812-4">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5098402812-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="5098402812-5">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5098402812-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="5098402812-6">}</span><span class="p" data-group-id="5098402812-3">]</span></code></pre><p>An application that has been stopped, or has never been started, can be
│ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="9409471235-2">(</span><span class="p" data-group-id="9409471235-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9409471235-3">[</span><span class="p" data-group-id="9409471235-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="9409471235-4">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9409471235-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="9409471235-5">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9409471235-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="9409471235-6">}</span><span class="p" data-group-id="9409471235-3">]</span></code></pre><p>An application that has been stopped, or has never been started, can be
│ │ │  unloaded. The information about the application is erased from the internal
│ │ │ -database of the application controller.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">unload</span><span class="p" data-group-id="9863869799-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="9863869799-1">)</span><span class="p">.</span><span class="w">
│ │ │ +database of the application controller.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">unload</span><span class="p" data-group-id="2657810537-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="2657810537-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="9863869799-2">(</span><span class="p" data-group-id="9863869799-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9863869799-3">[</span><span class="p" data-group-id="9863869799-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="9863869799-4">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9863869799-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="9863869799-5">}</span><span class="p" data-group-id="9863869799-3">]</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Loading/unloading an application does not load/unload the code used by the
│ │ │ +4&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">loaded_applications</span><span class="p" data-group-id="2657810537-2">(</span><span class="p" data-group-id="2657810537-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2657810537-3">[</span><span class="p" data-group-id="2657810537-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="2657810537-4">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2657810537-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="2657810537-5">}</span><span class="p" data-group-id="2657810537-3">]</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Loading/unloading an application does not load/unload the code used by the
│ │ │  application. Code loading is handled in the usual way by the code server.</p></section><p><a href="" id="stopping"></a></p><h2 id="starting-and-stopping-applications" class="section-heading">
│ │ │    <a href="#starting-and-stopping-applications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting and Stopping Applications</span>
│ │ │  </h2>
│ │ │ -<p>An application is started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4095341893-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="4095341893-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>An application is started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="3017647639-1">(</span><span class="ss">ch_app</span><span class="p" data-group-id="3017647639-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">which_applications</span><span class="p" data-group-id="4095341893-2">(</span><span class="p" data-group-id="4095341893-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4095341893-3">[</span><span class="p" data-group-id="4095341893-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="4095341893-4">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="4095341893-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="4095341893-5">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="4095341893-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="4095341893-6">}</span><span class="p" data-group-id="4095341893-3">]</span></code></pre><p>If the application is not already loaded, the application controller first loads
│ │ │ +6&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">which_applications</span><span class="p" data-group-id="3017647639-2">(</span><span class="p" data-group-id="3017647639-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3017647639-3">[</span><span class="p" data-group-id="3017647639-4">{</span><span class="ss">kernel</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;2.8.1.3&quot;</span><span class="p" data-group-id="3017647639-4">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3017647639-5">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="s">&quot;ERTS  CXC 138 10&quot;</span><span class="p">,</span><span class="s">&quot;1.11.4.3&quot;</span><span class="p" data-group-id="3017647639-5">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3017647639-6">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;Channel allocator&quot;</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="3017647639-6">}</span><span class="p" data-group-id="3017647639-3">]</span></code></pre><p>If the application is not already loaded, the application controller first loads
│ │ │  it using <a href="../../lib/kernel-10.2.7.2/doc/html/application.html#load/1"><code class="inline">application:load/1</code></a>. It checks the value of the <code class="inline">applications</code> key to
│ │ │  ensure that all applications that are to be started before this application are
│ │ │  running.</p><p><a href="" id="application_master"></a></p><p>Following that, the application controller creates an <em>application master</em> for
│ │ │  the application.</p><p>The application master establishes itself as the <a href="../../erts-15.2.7.3/doc/html/erlang.html#group_leader/0">group
│ │ │  leader</a> of all processes in the application
│ │ │  and will forward I/O to the previous group leader.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The purpose of the application master being the group leader is to easily
│ │ │  keep track of which processes that belong to the application. That is needed
│ │ │ @@ -347,55 +347,55 @@
│ │ │  defined by the <code class="inline">mod</code> key.</p><h2 id="configuring-an-application" class="section-heading">
│ │ │    <a href="#configuring-an-application" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Configuring an Application</span>
│ │ │  </h2>
│ │ │  <p>An application can be configured using <em>configuration parameters</em>. These are a
│ │ │ -list of <code class="inline">{Par,Val}</code> tuples specified by a key <code class="inline">env</code> in the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5197140301-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5197140301-2">[</span><span class="p" data-group-id="5197140301-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="5197140301-3">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5197140301-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="5197140301-4">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5197140301-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5197140301-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="5197140301-6">]</span><span class="p" data-group-id="5197140301-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5197140301-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5197140301-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="5197140301-8">]</span><span class="p" data-group-id="5197140301-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5197140301-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5197140301-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="5197140301-10">]</span><span class="p" data-group-id="5197140301-9">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5197140301-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5197140301-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="5197140301-13">[</span><span class="p" data-group-id="5197140301-13">]</span><span class="p" data-group-id="5197140301-12">}</span><span class="p" data-group-id="5197140301-11">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5197140301-14">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5197140301-15">[</span><span class="p" data-group-id="5197140301-16">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="5197140301-16">}</span><span class="p" data-group-id="5197140301-15">]</span><span class="p" data-group-id="5197140301-14">}</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5197140301-2">]</span><span class="p" data-group-id="5197140301-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Par</code> is to be an atom. <code class="inline">Val</code> is any term. The application can retrieve the
│ │ │ +list of <code class="inline">{Par,Val}</code> tuples specified by a key <code class="inline">env</code> in the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3727009057-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3727009057-2">[</span><span class="p" data-group-id="3727009057-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="3727009057-3">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3727009057-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="3727009057-4">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3727009057-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3727009057-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3727009057-6">]</span><span class="p" data-group-id="3727009057-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3727009057-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3727009057-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="3727009057-8">]</span><span class="p" data-group-id="3727009057-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3727009057-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3727009057-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="3727009057-10">]</span><span class="p" data-group-id="3727009057-9">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3727009057-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3727009057-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="3727009057-13">[</span><span class="p" data-group-id="3727009057-13">]</span><span class="p" data-group-id="3727009057-12">}</span><span class="p" data-group-id="3727009057-11">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3727009057-14">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3727009057-15">[</span><span class="p" data-group-id="3727009057-16">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="3727009057-16">}</span><span class="p" data-group-id="3727009057-15">]</span><span class="p" data-group-id="3727009057-14">}</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3727009057-2">]</span><span class="p" data-group-id="3727009057-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Par</code> is to be an atom. <code class="inline">Val</code> is any term. The application can retrieve the
│ │ │  value of a configuration parameter by calling <code class="inline">application:get_env(App, Par)</code> or
│ │ │  a number of similar functions. For more information, see module <a href="../../lib/kernel-10.2.7.2/doc/html/application.html"><code class="inline">application</code></a>
│ │ │  in Kernel.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="7594933250-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="7594933250-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="7594933250-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="7594933250-2">]</span><span class="w"> </span><span class="p" data-group-id="7594933250-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="7594933250-3">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="9860501310-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="9860501310-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="9860501310-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="9860501310-2">]</span><span class="w"> </span><span class="p" data-group-id="9860501310-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="9860501310-3">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="7594933250-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="7594933250-4">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7594933250-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="7594933250-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="9860501310-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="9860501310-4">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9860501310-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="9860501310-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="7594933250-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="7594933250-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7594933250-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="7594933250-7">}</span></code></pre><p>The values in the <code class="inline">.app</code> file can be overridden by values in a <em>system
│ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="9860501310-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="9860501310-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9860501310-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="9860501310-7">}</span></code></pre><p>The values in the <code class="inline">.app</code> file can be overridden by values in a <em>system
│ │ │  configuration file</em>. This is a file that contains configuration parameters for
│ │ │ -relevant applications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0311051331-1">[</span><span class="p" data-group-id="0311051331-2">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0311051331-3">[</span><span class="p" data-group-id="0311051331-4">{</span><span class="n">Par11</span><span class="p">,</span><span class="n">Val11</span><span class="p" data-group-id="0311051331-4">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0311051331-3">]</span><span class="p" data-group-id="0311051331-2">}</span><span class="p">,</span><span class="w">
│ │ │ +relevant applications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5214265233-1">[</span><span class="p" data-group-id="5214265233-2">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5214265233-3">[</span><span class="p" data-group-id="5214265233-4">{</span><span class="n">Par11</span><span class="p">,</span><span class="n">Val11</span><span class="p" data-group-id="5214265233-4">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5214265233-3">]</span><span class="p" data-group-id="5214265233-2">}</span><span class="p">,</span><span class="w">
│ │ │   </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0311051331-5">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0311051331-6">[</span><span class="p" data-group-id="0311051331-7">{</span><span class="n">ParN1</span><span class="p">,</span><span class="n">ValN1</span><span class="p" data-group-id="0311051331-7">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0311051331-6">]</span><span class="p" data-group-id="0311051331-5">}</span><span class="p" data-group-id="0311051331-1">]</span><span class="p">.</span></code></pre><p>The system configuration is to be called <code class="inline">Name.config</code> and Erlang is to be
│ │ │ + </span><span class="p" data-group-id="5214265233-5">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5214265233-6">[</span><span class="p" data-group-id="5214265233-7">{</span><span class="n">ParN1</span><span class="p">,</span><span class="n">ValN1</span><span class="p" data-group-id="5214265233-7">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5214265233-6">]</span><span class="p" data-group-id="5214265233-5">}</span><span class="p" data-group-id="5214265233-1">]</span><span class="p">.</span></code></pre><p>The system configuration is to be called <code class="inline">Name.config</code> and Erlang is to be
│ │ │  started with the command-line argument <code class="inline">-config Name</code>. For details, see
│ │ │  <a href="../../lib/kernel-10.2.7.2/doc/html/config.html"><code class="inline">config</code></a> in Kernel.</p><p><em>Example:</em></p><p>A file <code class="inline">test.config</code> is created with the following contents:</p><pre><code class="text">[{ch_app, [{file, &quot;testlog&quot;}]}].</code></pre><p>The value of <code class="inline">file</code> overrides the value of <code class="inline">file</code> as defined in the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -config test</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="8470971974-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="8470971974-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="8470971974-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="8470971974-2">]</span><span class="w"> </span><span class="p" data-group-id="8470971974-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="8470971974-3">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="4362672011-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="4362672011-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="4362672011-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="4362672011-2">]</span><span class="w"> </span><span class="p" data-group-id="4362672011-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="4362672011-3">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="8470971974-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="8470971974-4">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="8470971974-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="8470971974-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="4362672011-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="4362672011-4">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4362672011-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="4362672011-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="8470971974-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="8470971974-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8470971974-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="8470971974-7">}</span></code></pre><p>If <a href="release_handling.html#sys">release handling</a> is used, exactly one system
│ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="4362672011-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="4362672011-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4362672011-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="4362672011-7">}</span></code></pre><p>If <a href="release_handling.html#sys">release handling</a> is used, exactly one system
│ │ │  configuration file is to be used and that file is to be called <code class="inline">sys.config</code>.</p><p>The values in the <code class="inline">.app</code> file and the values in a system configuration file can
│ │ │  be overridden directly from the command line:</p><pre><code class="text">% erl -ApplName Par1 Val1 ... ParN ValN</code></pre><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -ch_app file &#39;&quot;testlog&quot;&#39;</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="2821028486-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="2821028486-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="2821028486-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="2821028486-2">]</span><span class="w"> </span><span class="p" data-group-id="2821028486-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="2821028486-3">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="p" data-group-id="4612817606-1">(</span><span class="n">BEAM</span><span class="p" data-group-id="4612817606-1">)</span><span class="w"> </span><span class="ss">emulator</span><span class="w"> </span><span class="ss">version</span><span class="w"> </span><span class="mf">5.2</span><span class="p">.</span><span class="mf">3.6</span><span class="w"> </span><span class="p" data-group-id="4612817606-2">[</span><span class="ss">hipe</span><span class="p" data-group-id="4612817606-2">]</span><span class="w"> </span><span class="p" data-group-id="4612817606-3">[</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="4612817606-3">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="2821028486-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="2821028486-4">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2821028486-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="2821028486-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">2.3</span><span class="p">.</span><span class="mi">6</span><span class="w">  </span><span class="p" data-group-id="4612817606-4">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="4612817606-4">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4612817606-5">(</span><span class="ss">ch_app</span><span class="p" data-group-id="4612817606-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="2821028486-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="2821028486-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2821028486-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="2821028486-7">}</span></code></pre><h2 id="application-start-types" class="section-heading">
│ │ │ +2&gt; </span><span class="nc">application</span><span class="p">:</span><span class="nf">get_env</span><span class="p" data-group-id="4612817606-6">(</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">file</span><span class="p" data-group-id="4612817606-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4612817606-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;testlog&quot;</span><span class="p" data-group-id="4612817606-7">}</span></code></pre><h2 id="application-start-types" class="section-heading">
│ │ │    <a href="#application-start-types" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Application Start Types</span>
│ │ │  </h2>
│ │ │  <p>A <em>start type</em> is defined when starting the application:</p><pre><code class="text">application:start(Application, Type)</code></pre><p><code class="inline">application:start(Application)</code> is the same as calling
│ │ │  <code class="inline">application:start(Application, temporary)</code>. The type can also be <code class="inline">permanent</code> or
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/appup_cookbook.html
│ │ │ @@ -120,18 +120,18 @@
│ │ │    <a href="#changing-a-functional-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing a Functional Module</span>
│ │ │  </h2>
│ │ │  <p>When a functional module has been changed, for example, if a new function has
│ │ │  been added or a bug has been corrected, simple code replacement is sufficient,
│ │ │ -for example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2945436968-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2945436968-2">[</span><span class="p" data-group-id="2945436968-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2945436968-4">[</span><span class="p" data-group-id="2945436968-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="2945436968-5">}</span><span class="p" data-group-id="2945436968-4">]</span><span class="p" data-group-id="2945436968-3">}</span><span class="p" data-group-id="2945436968-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2945436968-6">[</span><span class="p" data-group-id="2945436968-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2945436968-8">[</span><span class="p" data-group-id="2945436968-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="2945436968-9">}</span><span class="p" data-group-id="2945436968-8">]</span><span class="p" data-group-id="2945436968-7">}</span><span class="p" data-group-id="2945436968-6">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2945436968-1">}</span><span class="p">.</span></code></pre><h2 id="changing-a-residence-module" class="section-heading">
│ │ │ +for example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5254697054-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5254697054-2">[</span><span class="p" data-group-id="5254697054-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5254697054-4">[</span><span class="p" data-group-id="5254697054-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="5254697054-5">}</span><span class="p" data-group-id="5254697054-4">]</span><span class="p" data-group-id="5254697054-3">}</span><span class="p" data-group-id="5254697054-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5254697054-6">[</span><span class="p" data-group-id="5254697054-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5254697054-8">[</span><span class="p" data-group-id="5254697054-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="5254697054-9">}</span><span class="p" data-group-id="5254697054-8">]</span><span class="p" data-group-id="5254697054-7">}</span><span class="p" data-group-id="5254697054-6">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5254697054-1">}</span><span class="p">.</span></code></pre><h2 id="changing-a-residence-module" class="section-heading">
│ │ │    <a href="#changing-a-residence-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing a Residence Module</span>
│ │ │  </h2>
│ │ │  <p>In a system implemented according to the OTP design principles, all processes,
│ │ │  except system processes and special processes, reside in one of the behaviours
│ │ │ @@ -142,46 +142,46 @@
│ │ │    <a href="#changing-a-callback-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing a Callback Module</span>
│ │ │  </h2>
│ │ │  <p>A callback module is a functional module, and for code extensions simple code
│ │ │  replacement is sufficient.</p><p><em>Example</em></p><p>When adding a function to <code class="inline">ch3</code>, as described in the example in
│ │ │ -<a href="release_handling.html#appup">Release Handling</a>, <code class="inline">ch_app.appup</code> looks as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9557142678-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9557142678-2">[</span><span class="p" data-group-id="9557142678-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557142678-4">[</span><span class="p" data-group-id="9557142678-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="9557142678-5">}</span><span class="p" data-group-id="9557142678-4">]</span><span class="p" data-group-id="9557142678-3">}</span><span class="p" data-group-id="9557142678-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9557142678-6">[</span><span class="p" data-group-id="9557142678-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9557142678-8">[</span><span class="p" data-group-id="9557142678-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="9557142678-9">}</span><span class="p" data-group-id="9557142678-8">]</span><span class="p" data-group-id="9557142678-7">}</span><span class="p" data-group-id="9557142678-6">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9557142678-1">}</span><span class="p">.</span></code></pre><p>OTP also supports changing the internal state of behaviour processes; see
│ │ │ +<a href="release_handling.html#appup">Release Handling</a>, <code class="inline">ch_app.appup</code> looks as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1138861672-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1138861672-2">[</span><span class="p" data-group-id="1138861672-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1138861672-4">[</span><span class="p" data-group-id="1138861672-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1138861672-5">}</span><span class="p" data-group-id="1138861672-4">]</span><span class="p" data-group-id="1138861672-3">}</span><span class="p" data-group-id="1138861672-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1138861672-6">[</span><span class="p" data-group-id="1138861672-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1138861672-8">[</span><span class="p" data-group-id="1138861672-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1138861672-9">}</span><span class="p" data-group-id="1138861672-8">]</span><span class="p" data-group-id="1138861672-7">}</span><span class="p" data-group-id="1138861672-6">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1138861672-1">}</span><span class="p">.</span></code></pre><p>OTP also supports changing the internal state of behaviour processes; see
│ │ │  <a href="appup_cookbook.html#int_state">Changing Internal State</a>.</p><p><a href="" id="int_state"></a></p><h2 id="changing-internal-state" class="section-heading">
│ │ │    <a href="#changing-internal-state" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing Internal State</span>
│ │ │  </h2>
│ │ │  <p>In this case, simple code replacement is not sufficient. The process must
│ │ │  explicitly transform its state using the callback function <code class="inline">code_change/3</code> before
│ │ │  switching to the new version of the callback module. Thus, synchronized code
│ │ │  replacement is used.</p><p><em>Example</em></p><p>Consider the <code class="inline">ch3</code> module from
│ │ │  <a href="gen_server_concepts.html#ex">gen_server Behaviour</a>. The internal state is a term
│ │ │  <code class="inline">Chs</code> representing the available channels. Assume you want to add a counter <code class="inline">N</code>,
│ │ │  which keeps track of the number of <code class="inline">alloc</code> requests so far. This means that the
│ │ │ -format must be changed to <code class="inline">{Chs,N}</code>.</p><p>The <code class="inline">.appup</code> file can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8018401493-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8018401493-2">[</span><span class="p" data-group-id="8018401493-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8018401493-4">[</span><span class="p" data-group-id="8018401493-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8018401493-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8018401493-7">[</span><span class="p" data-group-id="8018401493-7">]</span><span class="p" data-group-id="8018401493-6">}</span><span class="p" data-group-id="8018401493-5">}</span><span class="p" data-group-id="8018401493-4">]</span><span class="p" data-group-id="8018401493-3">}</span><span class="p" data-group-id="8018401493-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8018401493-8">[</span><span class="p" data-group-id="8018401493-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8018401493-10">[</span><span class="p" data-group-id="8018401493-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8018401493-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8018401493-13">[</span><span class="p" data-group-id="8018401493-13">]</span><span class="p" data-group-id="8018401493-12">}</span><span class="p" data-group-id="8018401493-11">}</span><span class="p" data-group-id="8018401493-10">]</span><span class="p" data-group-id="8018401493-9">}</span><span class="p" data-group-id="8018401493-8">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8018401493-1">}</span><span class="p">.</span></code></pre><p>The third element of the <code class="inline">update</code> instruction is a tuple <code class="inline">{advanced,Extra}</code>,
│ │ │ +format must be changed to <code class="inline">{Chs,N}</code>.</p><p>The <code class="inline">.appup</code> file can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6082357830-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="6082357830-2">[</span><span class="p" data-group-id="6082357830-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6082357830-4">[</span><span class="p" data-group-id="6082357830-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6082357830-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6082357830-7">[</span><span class="p" data-group-id="6082357830-7">]</span><span class="p" data-group-id="6082357830-6">}</span><span class="p" data-group-id="6082357830-5">}</span><span class="p" data-group-id="6082357830-4">]</span><span class="p" data-group-id="6082357830-3">}</span><span class="p" data-group-id="6082357830-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="6082357830-8">[</span><span class="p" data-group-id="6082357830-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6082357830-10">[</span><span class="p" data-group-id="6082357830-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6082357830-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6082357830-13">[</span><span class="p" data-group-id="6082357830-13">]</span><span class="p" data-group-id="6082357830-12">}</span><span class="p" data-group-id="6082357830-11">}</span><span class="p" data-group-id="6082357830-10">]</span><span class="p" data-group-id="6082357830-9">}</span><span class="p" data-group-id="6082357830-8">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6082357830-1">}</span><span class="p">.</span></code></pre><p>The third element of the <code class="inline">update</code> instruction is a tuple <code class="inline">{advanced,Extra}</code>,
│ │ │  which says that the affected processes are to do a state transformation before
│ │ │  loading the new version of the module. This is done by the processes calling the
│ │ │  callback function <code class="inline">code_change/3</code> (see <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html"><code class="inline">gen_server</code></a> in STDLIB).
│ │ │ -The term <code class="inline">Extra</code>, in this case <code class="inline">[]</code>, is passed as is to the function:</p><p><a href="" id="code_change"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1131536264-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="1131536264-1">)</span><span class="p">.</span><span class="w">
│ │ │ +The term <code class="inline">Extra</code>, in this case <code class="inline">[]</code>, is passed as is to the function:</p><p><a href="" id="code_change"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5531551504-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="5531551504-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1131536264-2">(</span><span class="p" data-group-id="1131536264-3">[</span><span class="ss">code_change</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="1131536264-3">]</span><span class="p" data-group-id="1131536264-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5531551504-2">(</span><span class="p" data-group-id="5531551504-3">[</span><span class="ss">code_change</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5531551504-3">]</span><span class="p" data-group-id="5531551504-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">code_change</span><span class="p" data-group-id="1131536264-4">(</span><span class="p" data-group-id="1131536264-5">{</span><span class="ss">down</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vsn</span><span class="p" data-group-id="1131536264-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1131536264-6">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p" data-group-id="1131536264-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="1131536264-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1131536264-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="1131536264-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">code_change</span><span class="p" data-group-id="1131536264-8">(</span><span class="p">_</span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="1131536264-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1131536264-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1131536264-10">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="1131536264-10">}</span><span class="p" data-group-id="1131536264-9">}</span><span class="p">.</span></code></pre><p>The first argument is <code class="inline">{down,Vsn}</code> if there is a downgrade, or <code class="inline">Vsn</code> if there is
│ │ │ +</span><span class="nf">code_change</span><span class="p" data-group-id="5531551504-4">(</span><span class="p" data-group-id="5531551504-5">{</span><span class="ss">down</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vsn</span><span class="p" data-group-id="5531551504-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5531551504-6">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p" data-group-id="5531551504-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="5531551504-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5531551504-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="5531551504-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">code_change</span><span class="p" data-group-id="5531551504-8">(</span><span class="p">_</span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="5531551504-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5531551504-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5531551504-10">{</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="5531551504-10">}</span><span class="p" data-group-id="5531551504-9">}</span><span class="p">.</span></code></pre><p>The first argument is <code class="inline">{down,Vsn}</code> if there is a downgrade, or <code class="inline">Vsn</code> if there is
│ │ │  a upgrade. The term <code class="inline">Vsn</code> is fetched from the 'original' version of the module,
│ │ │  that is, the version you are upgrading from, or downgrading to.</p><p>The version is defined by the module attribute <code class="inline">vsn</code>, if any. There is no such
│ │ │  attribute in <code class="inline">ch3</code>, so in this case the version is the checksum (a huge integer)
│ │ │  of the beam file, an uninteresting value, which is ignored.</p><p>The other callback functions of <code class="inline">ch3</code> must also be modified and perhaps a new
│ │ │  interface function must be added, but this is not shown here.</p><h2 id="module-dependencies" class="section-heading">
│ │ │    <a href="#module-dependencies" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -190,67 +190,67 @@
│ │ │  </h2>
│ │ │  <p>Assume that a module is extended by adding an interface function, as in the
│ │ │  example in <a href="release_handling.html#appup">Release Handling</a>, where a function
│ │ │  <code class="inline">available/0</code> is added to <code class="inline">ch3</code>.</p><p>If a call is added to this function, say in module <code class="inline">m1</code>, a runtime error could
│ │ │  can occur during release upgrade if the new version of <code class="inline">m1</code> is loaded first and
│ │ │  calls <code class="inline">ch3:available/0</code> before the new version of <code class="inline">ch3</code> is loaded.</p><p>Thus, <code class="inline">ch3</code> must be loaded before <code class="inline">m1</code>, in the upgrade case, and conversely in
│ │ │  the downgrade case. <code class="inline">m1</code> is said to be <em>dependent on</em> <code class="inline">ch3</code>. In a release
│ │ │ -handling instruction, this is expressed by the <code class="inline">DepMods</code> element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7836887475-1">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="7836887475-1">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7836887475-2">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7836887475-3">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="7836887475-3">}</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="7836887475-2">}</span></code></pre><p><code class="inline">DepMods</code> is a list of modules, on which <code class="inline">Module</code> is dependent.</p><p><em>Example</em></p><p>The module <code class="inline">m1</code> in application <code class="inline">myapp</code> is dependent on <code class="inline">ch3</code> when
│ │ │ +handling instruction, this is expressed by the <code class="inline">DepMods</code> element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0279895470-1">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="0279895470-1">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0279895470-2">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0279895470-3">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="0279895470-3">}</span><span class="p">,</span><span class="w"> </span><span class="n">DepMods</span><span class="p" data-group-id="0279895470-2">}</span></code></pre><p><code class="inline">DepMods</code> is a list of modules, on which <code class="inline">Module</code> is dependent.</p><p><em>Example</em></p><p>The module <code class="inline">m1</code> in application <code class="inline">myapp</code> is dependent on <code class="inline">ch3</code> when
│ │ │  upgrading from &quot;1&quot; to &quot;2&quot;, or downgrading from &quot;2&quot; to &quot;1&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="ss">myapp</span><span class="p">.</span><span class="nc">appup</span><span class="p">:</span><span class="w">
│ │ │  
│ │ │ -</span><span class="p" data-group-id="1529092043-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1529092043-2">[</span><span class="p" data-group-id="1529092043-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529092043-4">[</span><span class="p" data-group-id="1529092043-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529092043-6">[</span><span class="ss">ch3</span><span class="p" data-group-id="1529092043-6">]</span><span class="p" data-group-id="1529092043-5">}</span><span class="p" data-group-id="1529092043-4">]</span><span class="p" data-group-id="1529092043-3">}</span><span class="p" data-group-id="1529092043-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1529092043-7">[</span><span class="p" data-group-id="1529092043-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529092043-9">[</span><span class="p" data-group-id="1529092043-10">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529092043-11">[</span><span class="ss">ch3</span><span class="p" data-group-id="1529092043-11">]</span><span class="p" data-group-id="1529092043-10">}</span><span class="p" data-group-id="1529092043-9">]</span><span class="p" data-group-id="1529092043-8">}</span><span class="p" data-group-id="1529092043-7">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1529092043-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8340629394-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8340629394-2">[</span><span class="p" data-group-id="8340629394-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8340629394-4">[</span><span class="p" data-group-id="8340629394-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8340629394-6">[</span><span class="ss">ch3</span><span class="p" data-group-id="8340629394-6">]</span><span class="p" data-group-id="8340629394-5">}</span><span class="p" data-group-id="8340629394-4">]</span><span class="p" data-group-id="8340629394-3">}</span><span class="p" data-group-id="8340629394-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8340629394-7">[</span><span class="p" data-group-id="8340629394-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8340629394-9">[</span><span class="p" data-group-id="8340629394-10">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8340629394-11">[</span><span class="ss">ch3</span><span class="p" data-group-id="8340629394-11">]</span><span class="p" data-group-id="8340629394-10">}</span><span class="p" data-group-id="8340629394-9">]</span><span class="p" data-group-id="8340629394-8">}</span><span class="p" data-group-id="8340629394-7">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8340629394-1">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="ss">ch_app</span><span class="p">.</span><span class="nc">appup</span><span class="p">:</span><span class="w">
│ │ │  
│ │ │ -</span><span class="p" data-group-id="1529092043-12">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1529092043-13">[</span><span class="p" data-group-id="1529092043-14">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529092043-15">[</span><span class="p" data-group-id="1529092043-16">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1529092043-16">}</span><span class="p" data-group-id="1529092043-15">]</span><span class="p" data-group-id="1529092043-14">}</span><span class="p" data-group-id="1529092043-13">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1529092043-17">[</span><span class="p" data-group-id="1529092043-18">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1529092043-19">[</span><span class="p" data-group-id="1529092043-20">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1529092043-20">}</span><span class="p" data-group-id="1529092043-19">]</span><span class="p" data-group-id="1529092043-18">}</span><span class="p" data-group-id="1529092043-17">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1529092043-12">}</span><span class="p">.</span></code></pre><p>If instead <code class="inline">m1</code> and <code class="inline">ch3</code> belong to the same application, the <code class="inline">.appup</code> file can
│ │ │ -look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6638327580-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="6638327580-2">[</span><span class="p" data-group-id="6638327580-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="6638327580-4">[</span><span class="p" data-group-id="6638327580-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="6638327580-5">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6638327580-6">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6638327580-7">[</span><span class="ss">ch3</span><span class="p" data-group-id="6638327580-7">]</span><span class="p" data-group-id="6638327580-6">}</span><span class="p" data-group-id="6638327580-4">]</span><span class="p" data-group-id="6638327580-3">}</span><span class="p" data-group-id="6638327580-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="6638327580-8">[</span><span class="p" data-group-id="6638327580-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="6638327580-10">[</span><span class="p" data-group-id="6638327580-11">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="6638327580-11">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6638327580-12">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6638327580-13">[</span><span class="ss">ch3</span><span class="p" data-group-id="6638327580-13">]</span><span class="p" data-group-id="6638327580-12">}</span><span class="p" data-group-id="6638327580-10">]</span><span class="p" data-group-id="6638327580-9">}</span><span class="p" data-group-id="6638327580-8">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6638327580-1">}</span><span class="p">.</span></code></pre><p><code class="inline">m1</code> is dependent on <code class="inline">ch3</code> also when downgrading. <code class="inline">systools</code> knows the
│ │ │ +</span><span class="p" data-group-id="8340629394-12">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8340629394-13">[</span><span class="p" data-group-id="8340629394-14">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8340629394-15">[</span><span class="p" data-group-id="8340629394-16">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8340629394-16">}</span><span class="p" data-group-id="8340629394-15">]</span><span class="p" data-group-id="8340629394-14">}</span><span class="p" data-group-id="8340629394-13">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8340629394-17">[</span><span class="p" data-group-id="8340629394-18">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8340629394-19">[</span><span class="p" data-group-id="8340629394-20">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8340629394-20">}</span><span class="p" data-group-id="8340629394-19">]</span><span class="p" data-group-id="8340629394-18">}</span><span class="p" data-group-id="8340629394-17">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8340629394-12">}</span><span class="p">.</span></code></pre><p>If instead <code class="inline">m1</code> and <code class="inline">ch3</code> belong to the same application, the <code class="inline">.appup</code> file can
│ │ │ +look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3008252120-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3008252120-2">[</span><span class="p" data-group-id="3008252120-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="3008252120-4">[</span><span class="p" data-group-id="3008252120-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3008252120-5">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3008252120-6">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3008252120-7">[</span><span class="ss">ch3</span><span class="p" data-group-id="3008252120-7">]</span><span class="p" data-group-id="3008252120-6">}</span><span class="p" data-group-id="3008252120-4">]</span><span class="p" data-group-id="3008252120-3">}</span><span class="p" data-group-id="3008252120-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3008252120-8">[</span><span class="p" data-group-id="3008252120-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="3008252120-10">[</span><span class="p" data-group-id="3008252120-11">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3008252120-11">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3008252120-12">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3008252120-13">[</span><span class="ss">ch3</span><span class="p" data-group-id="3008252120-13">]</span><span class="p" data-group-id="3008252120-12">}</span><span class="p" data-group-id="3008252120-10">]</span><span class="p" data-group-id="3008252120-9">}</span><span class="p" data-group-id="3008252120-8">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3008252120-1">}</span><span class="p">.</span></code></pre><p><code class="inline">m1</code> is dependent on <code class="inline">ch3</code> also when downgrading. <code class="inline">systools</code> knows the
│ │ │  difference between up- and downgrading and generates a correct <code class="inline">relup</code>, where
│ │ │  <code class="inline">ch3</code> is loaded before <code class="inline">m1</code> when upgrading, but <code class="inline">m1</code> is loaded before <code class="inline">ch3</code> when
│ │ │  downgrading.</p><p><a href="" id="spec"></a></p><h2 id="changing-code-for-a-special-process" class="section-heading">
│ │ │    <a href="#changing-code-for-a-special-process" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing Code for a Special Process</span>
│ │ │  </h2>
│ │ │  <p>In this case, simple code replacement is not sufficient. When a new version of a
│ │ │  residence module for a special process is loaded, the process must make a fully
│ │ │  qualified call to its loop function to switch to the new code. Thus,
│ │ │  synchronized code replacement must be used.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The name(s) of the user-defined residence module(s) must be listed in the
│ │ │  <code class="inline">Modules</code> part of the child specification for the special process. Otherwise
│ │ │  the release handler cannot find the process.</p></section><p><em>Example</em></p><p>Consider the example <code class="inline">ch4</code> in <a href="spec_proc.html#ex">sys and proc_lib</a>.
│ │ │ -When started by a supervisor, the child specification can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0457225749-1">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0457225749-2">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0457225749-3">[</span><span class="p" data-group-id="0457225749-3">]</span><span class="p" data-group-id="0457225749-2">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="ss">permanent</span><span class="p">,</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0457225749-4">[</span><span class="ss">ch4</span><span class="p" data-group-id="0457225749-4">]</span><span class="p" data-group-id="0457225749-1">}</span></code></pre><p>If <code class="inline">ch4</code> is part of the application <code class="inline">sp_app</code> and a new version of the module is
│ │ │ +When started by a supervisor, the child specification can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5866844648-1">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5866844648-2">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5866844648-3">[</span><span class="p" data-group-id="5866844648-3">]</span><span class="p" data-group-id="5866844648-2">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="ss">permanent</span><span class="p">,</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5866844648-4">[</span><span class="ss">ch4</span><span class="p" data-group-id="5866844648-4">]</span><span class="p" data-group-id="5866844648-1">}</span></code></pre><p>If <code class="inline">ch4</code> is part of the application <code class="inline">sp_app</code> and a new version of the module is
│ │ │  to be loaded when upgrading from version &quot;1&quot; to &quot;2&quot; of this application,
│ │ │ -<code class="inline">sp_app.appup</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8702111259-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8702111259-2">[</span><span class="p" data-group-id="8702111259-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8702111259-4">[</span><span class="p" data-group-id="8702111259-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8702111259-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8702111259-7">[</span><span class="p" data-group-id="8702111259-7">]</span><span class="p" data-group-id="8702111259-6">}</span><span class="p" data-group-id="8702111259-5">}</span><span class="p" data-group-id="8702111259-4">]</span><span class="p" data-group-id="8702111259-3">}</span><span class="p" data-group-id="8702111259-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8702111259-8">[</span><span class="p" data-group-id="8702111259-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8702111259-10">[</span><span class="p" data-group-id="8702111259-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8702111259-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8702111259-13">[</span><span class="p" data-group-id="8702111259-13">]</span><span class="p" data-group-id="8702111259-12">}</span><span class="p" data-group-id="8702111259-11">}</span><span class="p" data-group-id="8702111259-10">]</span><span class="p" data-group-id="8702111259-9">}</span><span class="p" data-group-id="8702111259-8">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8702111259-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">update</code> instruction must contain the tuple <code class="inline">{advanced,Extra}</code>. The
│ │ │ +<code class="inline">sp_app.appup</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5223068594-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5223068594-2">[</span><span class="p" data-group-id="5223068594-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5223068594-4">[</span><span class="p" data-group-id="5223068594-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5223068594-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5223068594-7">[</span><span class="p" data-group-id="5223068594-7">]</span><span class="p" data-group-id="5223068594-6">}</span><span class="p" data-group-id="5223068594-5">}</span><span class="p" data-group-id="5223068594-4">]</span><span class="p" data-group-id="5223068594-3">}</span><span class="p" data-group-id="5223068594-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5223068594-8">[</span><span class="p" data-group-id="5223068594-9">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5223068594-10">[</span><span class="p" data-group-id="5223068594-11">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5223068594-12">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5223068594-13">[</span><span class="p" data-group-id="5223068594-13">]</span><span class="p" data-group-id="5223068594-12">}</span><span class="p" data-group-id="5223068594-11">}</span><span class="p" data-group-id="5223068594-10">]</span><span class="p" data-group-id="5223068594-9">}</span><span class="p" data-group-id="5223068594-8">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5223068594-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">update</code> instruction must contain the tuple <code class="inline">{advanced,Extra}</code>. The
│ │ │  instruction makes the special process call the callback function
│ │ │  <code class="inline">system_code_change/4</code>, a function the user must implement. The term <code class="inline">Extra</code>, in
│ │ │ -this case <code class="inline">[]</code>, is passed as is to <code class="inline">system_code_change/4</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4393016214-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="4393016214-1">)</span><span class="p">.</span><span class="w">
│ │ │ +this case <code class="inline">[]</code>, is passed as is to <code class="inline">system_code_change/4</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4840375203-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="4840375203-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4393016214-2">(</span><span class="p" data-group-id="4393016214-3">[</span><span class="ss">system_code_change</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="4393016214-3">]</span><span class="p" data-group-id="4393016214-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4840375203-2">(</span><span class="p" data-group-id="4840375203-3">[</span><span class="ss">system_code_change</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="4840375203-3">]</span><span class="p" data-group-id="4840375203-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_code_change</span><span class="p" data-group-id="4393016214-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="4393016214-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4393016214-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4393016214-5">}</span><span class="p">.</span></code></pre><ul><li>The first argument is the internal state <code class="inline">State</code>, passed from
│ │ │ +</span><span class="nf">system_code_change</span><span class="p" data-group-id="4840375203-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Extra</span><span class="p" data-group-id="4840375203-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4840375203-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4840375203-5">}</span><span class="p">.</span></code></pre><ul><li>The first argument is the internal state <code class="inline">State</code>, passed from
│ │ │  function <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg(Request, From, Parent, Module, Deb, State)</code></a>, and called by the special
│ │ │  process when a system message is received. In <code class="inline">ch4</code>, the internal
│ │ │  state is the set of available channels <code class="inline">Chs</code>.</li><li>The second argument is the name of the module (<code class="inline">ch4</code>).</li><li>The third argument is <code class="inline">Vsn</code> or <code class="inline">{down,Vsn}</code>, as described for
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#c:code_change/3"><code class="inline">gen_server:code_change/3</code></a> in
│ │ │  <a href="appup_cookbook.html#code_change">Changing Internal State</a>.</li></ul><p>In this case, all arguments but the first are ignored and the function simply
│ │ │  returns the internal state again. This is enough if the code only has been
│ │ │  extended. If instead the internal state is changed (similar to the example in
│ │ │ @@ -271,85 +271,85 @@
│ │ │    <span class="text">Changing Properties</span>
│ │ │  </h3>
│ │ │  <p>Since the supervisor is to change its internal state, synchronized code
│ │ │  replacement is required. However, a special <code class="inline">update</code> instruction must be used.</p><p>First, the new version of the callback module must be loaded, both in the case
│ │ │  of upgrade and downgrade. Then the new return value of <code class="inline">init/1</code> can be checked
│ │ │  and the internal state be changed accordingly.</p><p>The following <code class="inline">upgrade</code> instruction is used for supervisors:</p><pre><code class="text">{update, Module, supervisor}</code></pre><p><em>Example</em></p><p>To change the restart strategy of <code class="inline">ch_sup</code> (from
│ │ │  <a href="sup_princ.html#ex">Supervisor Behaviour</a>) from <code class="inline">one_for_one</code> to <code class="inline">one_for_all</code>,
│ │ │ -change the callback function <code class="inline">init/1</code> in <code class="inline">ch_sup.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2870570381-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="2870570381-1">)</span><span class="p">.</span><span class="w">
│ │ │ +change the callback function <code class="inline">init/1</code> in <code class="inline">ch_sup.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1518578669-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="1518578669-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="2870570381-2">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="2870570381-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2870570381-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2870570381-4">{</span><span class="p" data-group-id="2870570381-5">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_all</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2870570381-5">}</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2870570381-4">}</span><span class="p" data-group-id="2870570381-3">}</span><span class="p">.</span></code></pre><p>The file <code class="inline">ch_app.appup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7723142591-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7723142591-2">[</span><span class="p" data-group-id="7723142591-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7723142591-4">[</span><span class="p" data-group-id="7723142591-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="7723142591-5">}</span><span class="p" data-group-id="7723142591-4">]</span><span class="p" data-group-id="7723142591-3">}</span><span class="p" data-group-id="7723142591-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7723142591-6">[</span><span class="p" data-group-id="7723142591-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7723142591-8">[</span><span class="p" data-group-id="7723142591-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="7723142591-9">}</span><span class="p" data-group-id="7723142591-8">]</span><span class="p" data-group-id="7723142591-7">}</span><span class="p" data-group-id="7723142591-6">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7723142591-1">}</span><span class="p">.</span></code></pre><h3 id="changing-child-specifications" class="section-heading">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="1518578669-2">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="1518578669-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1518578669-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1518578669-4">{</span><span class="p" data-group-id="1518578669-5">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_all</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1518578669-5">}</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1518578669-4">}</span><span class="p" data-group-id="1518578669-3">}</span><span class="p">.</span></code></pre><p>The file <code class="inline">ch_app.appup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1866272378-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1866272378-2">[</span><span class="p" data-group-id="1866272378-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1866272378-4">[</span><span class="p" data-group-id="1866272378-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1866272378-5">}</span><span class="p" data-group-id="1866272378-4">]</span><span class="p" data-group-id="1866272378-3">}</span><span class="p" data-group-id="1866272378-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1866272378-6">[</span><span class="p" data-group-id="1866272378-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1866272378-8">[</span><span class="p" data-group-id="1866272378-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1866272378-9">}</span><span class="p" data-group-id="1866272378-8">]</span><span class="p" data-group-id="1866272378-7">}</span><span class="p" data-group-id="1866272378-6">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1866272378-1">}</span><span class="p">.</span></code></pre><h3 id="changing-child-specifications" class="section-heading">
│ │ │    <a href="#changing-child-specifications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing Child Specifications</span>
│ │ │  </h3>
│ │ │  <p>The instruction, and thus the <code class="inline">.appup</code> file, when changing an existing child
│ │ │ -specification, is the same as when changing properties as described earlier:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9250366425-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9250366425-2">[</span><span class="p" data-group-id="9250366425-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9250366425-4">[</span><span class="p" data-group-id="9250366425-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="9250366425-5">}</span><span class="p" data-group-id="9250366425-4">]</span><span class="p" data-group-id="9250366425-3">}</span><span class="p" data-group-id="9250366425-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9250366425-6">[</span><span class="p" data-group-id="9250366425-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9250366425-8">[</span><span class="p" data-group-id="9250366425-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="9250366425-9">}</span><span class="p" data-group-id="9250366425-8">]</span><span class="p" data-group-id="9250366425-7">}</span><span class="p" data-group-id="9250366425-6">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9250366425-1">}</span><span class="p">.</span></code></pre><p>The changes do not affect existing child processes. For example, changing the
│ │ │ +specification, is the same as when changing properties as described earlier:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2855720890-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2855720890-2">[</span><span class="p" data-group-id="2855720890-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2855720890-4">[</span><span class="p" data-group-id="2855720890-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2855720890-5">}</span><span class="p" data-group-id="2855720890-4">]</span><span class="p" data-group-id="2855720890-3">}</span><span class="p" data-group-id="2855720890-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2855720890-6">[</span><span class="p" data-group-id="2855720890-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2855720890-8">[</span><span class="p" data-group-id="2855720890-9">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2855720890-9">}</span><span class="p" data-group-id="2855720890-8">]</span><span class="p" data-group-id="2855720890-7">}</span><span class="p" data-group-id="2855720890-6">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2855720890-1">}</span><span class="p">.</span></code></pre><p>The changes do not affect existing child processes. For example, changing the
│ │ │  start function only specifies how the child process is to be restarted, if
│ │ │  needed later on.</p><p>The id of the child specification cannot be changed.</p><p>Changing the <code class="inline">Modules</code> field of the child specification can affect the release
│ │ │  handling process itself, as this field is used to identify which processes are
│ │ │  affected when doing a synchronized code replacement.</p><p><a href="" id="sup_add"></a></p><h3 id="adding-and-deleting-child-processes" class="section-heading">
│ │ │    <a href="#adding-and-deleting-child-processes" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Adding and Deleting Child Processes</span>
│ │ │  </h3>
│ │ │  <p>As stated earlier, changing child specifications does not affect existing child
│ │ │  processes. New child specifications are automatically added, but not deleted.
│ │ │  Child processes are not automatically started or terminated, this must be done
│ │ │  using <code class="inline">apply</code> instructions.</p><p><em>Example</em></p><p>Assume a new child process <code class="inline">m1</code> is to be added to <code class="inline">ch_sup</code> when
│ │ │  upgrading <code class="inline">ch_app</code> from &quot;1&quot; to &quot;2&quot;. This means <code class="inline">m1</code> is to be deleted when
│ │ │ -downgrading from &quot;2&quot; to &quot;1&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1389533947-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1389533947-2">[</span><span class="p" data-group-id="1389533947-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="1389533947-4">[</span><span class="p" data-group-id="1389533947-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1389533947-5">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1389533947-6">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1389533947-7">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1389533947-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1389533947-8">]</span><span class="p" data-group-id="1389533947-7">}</span><span class="p" data-group-id="1389533947-6">}</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="1389533947-4">]</span><span class="p" data-group-id="1389533947-3">}</span><span class="p" data-group-id="1389533947-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1389533947-9">[</span><span class="p" data-group-id="1389533947-10">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="1389533947-11">[</span><span class="p" data-group-id="1389533947-12">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1389533947-13">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1389533947-14">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1389533947-14">]</span><span class="p" data-group-id="1389533947-13">}</span><span class="p" data-group-id="1389533947-12">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1389533947-15">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1389533947-16">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1389533947-17">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="1389533947-17">]</span><span class="p" data-group-id="1389533947-16">}</span><span class="p" data-group-id="1389533947-15">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1389533947-18">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="1389533947-18">}</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="1389533947-11">]</span><span class="p" data-group-id="1389533947-10">}</span><span class="p" data-group-id="1389533947-9">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1389533947-1">}</span><span class="p">.</span></code></pre><p>The order of the instructions is important.</p><p>The supervisor must be registered as <code class="inline">ch_sup</code> for the script to work. If the
│ │ │ +downgrading from &quot;2&quot; to &quot;1&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2671871107-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2671871107-2">[</span><span class="p" data-group-id="2671871107-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="2671871107-4">[</span><span class="p" data-group-id="2671871107-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2671871107-5">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2671871107-6">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2671871107-7">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2671871107-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="2671871107-8">]</span><span class="p" data-group-id="2671871107-7">}</span><span class="p" data-group-id="2671871107-6">}</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="2671871107-4">]</span><span class="p" data-group-id="2671871107-3">}</span><span class="p" data-group-id="2671871107-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2671871107-9">[</span><span class="p" data-group-id="2671871107-10">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="2671871107-11">[</span><span class="p" data-group-id="2671871107-12">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2671871107-13">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2671871107-14">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="2671871107-14">]</span><span class="p" data-group-id="2671871107-13">}</span><span class="p" data-group-id="2671871107-12">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2671871107-15">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2671871107-16">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2671871107-17">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="2671871107-17">]</span><span class="p" data-group-id="2671871107-16">}</span><span class="p" data-group-id="2671871107-15">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2671871107-18">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="2671871107-18">}</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="2671871107-11">]</span><span class="p" data-group-id="2671871107-10">}</span><span class="p" data-group-id="2671871107-9">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2671871107-1">}</span><span class="p">.</span></code></pre><p>The order of the instructions is important.</p><p>The supervisor must be registered as <code class="inline">ch_sup</code> for the script to work. If the
│ │ │  supervisor is not registered, it cannot be accessed directly from the script.
│ │ │  Instead a help function that finds the pid of the supervisor and calls
│ │ │  <code class="inline">supervisor:restart_child</code>, and so on, must be written. This function is then to
│ │ │  be called from the script using the <code class="inline">apply</code> instruction.</p><p>If the module <code class="inline">m1</code> is introduced in version &quot;2&quot; of <code class="inline">ch_app</code>, it must also be
│ │ │ -loaded when upgrading and deleted when downgrading:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9047529060-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9047529060-2">[</span><span class="p" data-group-id="9047529060-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="9047529060-4">[</span><span class="p" data-group-id="9047529060-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="9047529060-5">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9047529060-6">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="9047529060-6">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9047529060-7">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9047529060-8">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9047529060-9">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="9047529060-9">]</span><span class="p" data-group-id="9047529060-8">}</span><span class="p" data-group-id="9047529060-7">}</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="9047529060-4">]</span><span class="p" data-group-id="9047529060-3">}</span><span class="p" data-group-id="9047529060-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9047529060-10">[</span><span class="p" data-group-id="9047529060-11">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="9047529060-12">[</span><span class="p" data-group-id="9047529060-13">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9047529060-14">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9047529060-15">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="9047529060-15">]</span><span class="p" data-group-id="9047529060-14">}</span><span class="p" data-group-id="9047529060-13">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9047529060-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9047529060-17">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9047529060-18">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="9047529060-18">]</span><span class="p" data-group-id="9047529060-17">}</span><span class="p" data-group-id="9047529060-16">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9047529060-19">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="9047529060-19">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9047529060-20">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="9047529060-20">}</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="9047529060-12">]</span><span class="p" data-group-id="9047529060-11">}</span><span class="p" data-group-id="9047529060-10">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9047529060-1">}</span><span class="p">.</span></code></pre><p>As stated earlier, the order of the instructions is important. When upgrading,
│ │ │ +loaded when upgrading and deleted when downgrading:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8011537255-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8011537255-2">[</span><span class="p" data-group-id="8011537255-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="8011537255-4">[</span><span class="p" data-group-id="8011537255-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8011537255-5">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8011537255-6">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="8011537255-6">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8011537255-7">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8011537255-8">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">restart_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8011537255-9">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8011537255-9">]</span><span class="p" data-group-id="8011537255-8">}</span><span class="p" data-group-id="8011537255-7">}</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="8011537255-4">]</span><span class="p" data-group-id="8011537255-3">}</span><span class="p" data-group-id="8011537255-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8011537255-10">[</span><span class="p" data-group-id="8011537255-11">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="8011537255-12">[</span><span class="p" data-group-id="8011537255-13">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8011537255-14">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8011537255-15">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8011537255-15">]</span><span class="p" data-group-id="8011537255-14">}</span><span class="p" data-group-id="8011537255-13">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8011537255-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8011537255-17">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="w"> </span><span class="ss">delete_child</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8011537255-18">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8011537255-18">]</span><span class="p" data-group-id="8011537255-17">}</span><span class="p" data-group-id="8011537255-16">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8011537255-19">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="8011537255-19">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8011537255-20">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m1</span><span class="p" data-group-id="8011537255-20">}</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="8011537255-12">]</span><span class="p" data-group-id="8011537255-11">}</span><span class="p" data-group-id="8011537255-10">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8011537255-1">}</span><span class="p">.</span></code></pre><p>As stated earlier, the order of the instructions is important. When upgrading,
│ │ │  <code class="inline">m1</code> must be loaded, and the supervisor child specification changed, before the
│ │ │  new child process can be started. When downgrading, the child process must be
│ │ │  terminated before the child specification is changed and the module is deleted.</p><h2 id="adding-or-deleting-a-module" class="section-heading">
│ │ │    <a href="#adding-or-deleting-a-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Adding or Deleting a Module</span>
│ │ │  </h2>
│ │ │ -<p>_Example</p><p>_ A new functional module <code class="inline">m</code> is added to <code class="inline">ch_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4826429847-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="4826429847-2">[</span><span class="p" data-group-id="4826429847-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4826429847-4">[</span><span class="p" data-group-id="4826429847-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="4826429847-5">}</span><span class="p" data-group-id="4826429847-4">]</span><span class="p" data-group-id="4826429847-3">}</span><span class="p" data-group-id="4826429847-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="4826429847-6">[</span><span class="p" data-group-id="4826429847-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4826429847-8">[</span><span class="p" data-group-id="4826429847-9">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="4826429847-9">}</span><span class="p" data-group-id="4826429847-8">]</span><span class="p" data-group-id="4826429847-7">}</span><span class="p" data-group-id="4826429847-6">]</span></code></pre><h2 id="starting-or-terminating-a-process" class="section-heading">
│ │ │ +<p>_Example</p><p>_ A new functional module <code class="inline">m</code> is added to <code class="inline">ch_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8145261330-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8145261330-2">[</span><span class="p" data-group-id="8145261330-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8145261330-4">[</span><span class="p" data-group-id="8145261330-5">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="8145261330-5">}</span><span class="p" data-group-id="8145261330-4">]</span><span class="p" data-group-id="8145261330-3">}</span><span class="p" data-group-id="8145261330-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8145261330-6">[</span><span class="p" data-group-id="8145261330-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8145261330-8">[</span><span class="p" data-group-id="8145261330-9">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="ss">m</span><span class="p" data-group-id="8145261330-9">}</span><span class="p" data-group-id="8145261330-8">]</span><span class="p" data-group-id="8145261330-7">}</span><span class="p" data-group-id="8145261330-6">]</span></code></pre><h2 id="starting-or-terminating-a-process" class="section-heading">
│ │ │    <a href="#starting-or-terminating-a-process" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting or Terminating a Process</span>
│ │ │  </h2>
│ │ │  <p>In a system structured according to the OTP design principles, any process would
│ │ │  be a child process belonging to a supervisor, see
│ │ │ @@ -369,29 +369,29 @@
│ │ │    <span class="text">Restarting an Application</span>
│ │ │  </h2>
│ │ │  <p>Restarting an application is useful when a change is too complicated to be made
│ │ │  without restarting the processes, for example, if the supervisor hierarchy has
│ │ │  been restructured.</p><p><em>Example</em></p><p>When adding a child <code class="inline">m1</code> to <code class="inline">ch_sup</code>, as in
│ │ │  <a href="appup_cookbook.html#sup_add">Adding and Deleting Child Processes</a> in Changing a
│ │ │  Supervisor, an alternative to updating the supervisor is to restart the entire
│ │ │ -application:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9198736376-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9198736376-2">[</span><span class="p" data-group-id="9198736376-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9198736376-4">[</span><span class="p" data-group-id="9198736376-5">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="9198736376-5">}</span><span class="p" data-group-id="9198736376-4">]</span><span class="p" data-group-id="9198736376-3">}</span><span class="p" data-group-id="9198736376-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9198736376-6">[</span><span class="p" data-group-id="9198736376-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9198736376-8">[</span><span class="p" data-group-id="9198736376-9">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="9198736376-9">}</span><span class="p" data-group-id="9198736376-8">]</span><span class="p" data-group-id="9198736376-7">}</span><span class="p" data-group-id="9198736376-6">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9198736376-1">}</span><span class="p">.</span></code></pre><p><a href="" id="app_spec"></a></p><h2 id="changing-an-application-specification" class="section-heading">
│ │ │ +application:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1493767174-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1493767174-2">[</span><span class="p" data-group-id="1493767174-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1493767174-4">[</span><span class="p" data-group-id="1493767174-5">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="1493767174-5">}</span><span class="p" data-group-id="1493767174-4">]</span><span class="p" data-group-id="1493767174-3">}</span><span class="p" data-group-id="1493767174-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1493767174-6">[</span><span class="p" data-group-id="1493767174-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1493767174-8">[</span><span class="p" data-group-id="1493767174-9">{</span><span class="ss">restart_application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p" data-group-id="1493767174-9">}</span><span class="p" data-group-id="1493767174-8">]</span><span class="p" data-group-id="1493767174-7">}</span><span class="p" data-group-id="1493767174-6">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1493767174-1">}</span><span class="p">.</span></code></pre><p><a href="" id="app_spec"></a></p><h2 id="changing-an-application-specification" class="section-heading">
│ │ │    <a href="#changing-an-application-specification" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing an Application Specification</span>
│ │ │  </h2>
│ │ │  <p>When installing a release, the application specifications are automatically
│ │ │  updated before evaluating the <code class="inline">relup</code> script. Thus, no instructions are needed
│ │ │ -in the <code class="inline">.appup</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9390786523-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9390786523-2">[</span><span class="p" data-group-id="9390786523-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9390786523-4">[</span><span class="p" data-group-id="9390786523-4">]</span><span class="p" data-group-id="9390786523-3">}</span><span class="p" data-group-id="9390786523-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9390786523-5">[</span><span class="p" data-group-id="9390786523-6">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9390786523-7">[</span><span class="p" data-group-id="9390786523-7">]</span><span class="p" data-group-id="9390786523-6">}</span><span class="p" data-group-id="9390786523-5">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9390786523-1">}</span><span class="p">.</span></code></pre><h2 id="changing-application-configuration" class="section-heading">
│ │ │ +in the <code class="inline">.appup</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1627318848-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1627318848-2">[</span><span class="p" data-group-id="1627318848-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1627318848-4">[</span><span class="p" data-group-id="1627318848-4">]</span><span class="p" data-group-id="1627318848-3">}</span><span class="p" data-group-id="1627318848-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1627318848-5">[</span><span class="p" data-group-id="1627318848-6">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1627318848-7">[</span><span class="p" data-group-id="1627318848-7">]</span><span class="p" data-group-id="1627318848-6">}</span><span class="p" data-group-id="1627318848-5">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1627318848-1">}</span><span class="p">.</span></code></pre><h2 id="changing-application-configuration" class="section-heading">
│ │ │    <a href="#changing-application-configuration" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing Application Configuration</span>
│ │ │  </h2>
│ │ │  <p>Changing an application configuration by updating the <code class="inline">env</code> key in the <code class="inline">.app</code>
│ │ │  file is an instance of changing an application specification, see the previous
│ │ │ @@ -406,26 +406,26 @@
│ │ │  applications apply to primary applications only. There are no corresponding
│ │ │  instructions for included applications. However, since an included application
│ │ │  is really a supervision tree with a topmost supervisor, started as a child
│ │ │  process to a supervisor in the including application, a <code class="inline">.relup</code> file can be
│ │ │  manually created.</p><p><em>Example</em></p><p>Assume there is a release containing an application <code class="inline">prim_app</code>, which
│ │ │  have a supervisor <code class="inline">prim_sup</code> in its supervision tree.</p><p>In a new version of the release, the application <code class="inline">ch_app</code> is to be included in
│ │ │  <code class="inline">prim_app</code>. That is, its topmost supervisor <code class="inline">ch_sup</code> is to be started as a child
│ │ │ -process to <code class="inline">prim_sup</code>.</p><p>The workflow is as follows:</p><p><em>Step 1)</em> Edit the code for <code class="inline">prim_sup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1135168457-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1135168457-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1135168457-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1135168457-3">{</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="ss">supervisor</span><span class="w"> </span><span class="ss">flags</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="1135168457-4">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -           </span><span class="p" data-group-id="1135168457-5">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1135168457-6">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="1135168457-7">[</span><span class="p" data-group-id="1135168457-7">]</span><span class="p" data-group-id="1135168457-6">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="ss">permanent</span><span class="p">,</span><span class="ss">infinity</span><span class="p">,</span><span class="ss">supervisor</span><span class="p">,</span><span class="p" data-group-id="1135168457-8">[</span><span class="ss">ch_sup</span><span class="p" data-group-id="1135168457-8">]</span><span class="p" data-group-id="1135168457-5">}</span><span class="p">,</span><span class="w">
│ │ │ -           </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1135168457-4">]</span><span class="p" data-group-id="1135168457-3">}</span><span class="p" data-group-id="1135168457-2">}</span><span class="p">.</span></code></pre><p><em>Step 2)</em> Edit the <code class="inline">.app</code> file for <code class="inline">prim_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3445416961-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="3445416961-2">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="3445416961-3">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="3445416961-3">}</span><span class="p">,</span><span class="w">
│ │ │ +process to <code class="inline">prim_sup</code>.</p><p>The workflow is as follows:</p><p><em>Step 1)</em> Edit the code for <code class="inline">prim_sup</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0520664009-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0520664009-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0520664009-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0520664009-3">{</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="ss">supervisor</span><span class="w"> </span><span class="ss">flags</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="0520664009-4">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ +           </span><span class="p" data-group-id="0520664009-5">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0520664009-6">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="0520664009-7">[</span><span class="p" data-group-id="0520664009-7">]</span><span class="p" data-group-id="0520664009-6">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="ss">permanent</span><span class="p">,</span><span class="ss">infinity</span><span class="p">,</span><span class="ss">supervisor</span><span class="p">,</span><span class="p" data-group-id="0520664009-8">[</span><span class="ss">ch_sup</span><span class="p" data-group-id="0520664009-8">]</span><span class="p" data-group-id="0520664009-5">}</span><span class="p">,</span><span class="w">
│ │ │ +           </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0520664009-4">]</span><span class="p" data-group-id="0520664009-3">}</span><span class="p" data-group-id="0520664009-2">}</span><span class="p">.</span></code></pre><p><em>Step 2)</em> Edit the <code class="inline">.app</code> file for <code class="inline">prim_app</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5721802752-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5721802752-2">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5721802752-3">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="5721802752-3">}</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="3445416961-4">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3445416961-5">[</span><span class="ss">ch_app</span><span class="p" data-group-id="3445416961-5">]</span><span class="p" data-group-id="3445416961-4">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5721802752-4">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5721802752-5">[</span><span class="ss">ch_app</span><span class="p" data-group-id="5721802752-5">]</span><span class="p" data-group-id="5721802752-4">}</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="3445416961-2">]</span><span class="p" data-group-id="3445416961-1">}</span><span class="p">.</span></code></pre><p><em>Step 3)</em> Create a new <code class="inline">.rel</code> file, including <code class="inline">ch_app</code>:</p><pre><code class="text">{release,
│ │ │ + </span><span class="p" data-group-id="5721802752-2">]</span><span class="p" data-group-id="5721802752-1">}</span><span class="p">.</span></code></pre><p><em>Step 3)</em> Create a new <code class="inline">.rel</code> file, including <code class="inline">ch_app</code>:</p><pre><code class="text">{release,
│ │ │   ...,
│ │ │   [...,
│ │ │    {prim_app, &quot;2&quot;},
│ │ │    {ch_app, &quot;1&quot;}]}.</code></pre><p>The included application can be started in two ways. This is described in the
│ │ │  next two sections.</p><h3 id="application-restart" class="section-heading">
│ │ │    <a href="#application-restart" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -480,74 +480,74 @@
│ │ │  <p><em>Step 4b)</em> Another way to start the included application (or stop it in the case
│ │ │  of downgrade) is by combining instructions for adding and removing child
│ │ │  processes to/from <code class="inline">prim_sup</code> with instructions for loading/unloading all
│ │ │  <code class="inline">ch_app</code> code and its application specification.</p><p>Again, the <code class="inline">.relup</code> file is created manually, either from scratch or by editing a
│ │ │  generated version. Load all code for <code class="inline">ch_app</code> first, and also load the
│ │ │  application specification, before <code class="inline">prim_sup</code> is updated. When downgrading,
│ │ │  <code class="inline">prim_sup</code> is to updated first, before the code for <code class="inline">ch_app</code> and its application
│ │ │ -specification are unloaded.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4122998069-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="4122998069-2">[</span><span class="p" data-group-id="4122998069-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="4122998069-4">[</span><span class="p" data-group-id="4122998069-4">]</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="4122998069-5">[</span><span class="p" data-group-id="4122998069-6">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="4122998069-7">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="4122998069-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="4122998069-8">]</span><span class="p" data-group-id="4122998069-7">}</span><span class="p" data-group-id="4122998069-6">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-9">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="4122998069-10">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="p" data-group-id="4122998069-11">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="4122998069-11">]</span><span class="p" data-group-id="4122998069-10">}</span><span class="p" data-group-id="4122998069-9">}</span><span class="p">,</span><span class="w">
│ │ │ +specification are unloaded.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6748954964-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="6748954964-2">[</span><span class="p" data-group-id="6748954964-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="6748954964-4">[</span><span class="p" data-group-id="6748954964-4">]</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="6748954964-5">[</span><span class="p" data-group-id="6748954964-6">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="6748954964-7">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="6748954964-8">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="6748954964-8">]</span><span class="p" data-group-id="6748954964-7">}</span><span class="p" data-group-id="6748954964-6">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-9">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="6748954964-10">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="p" data-group-id="6748954964-11">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="6748954964-11">]</span><span class="p" data-group-id="6748954964-10">}</span><span class="p" data-group-id="6748954964-9">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">point_of_no_return</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-12">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="4122998069-13">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="4122998069-13">}</span><span class="p" data-group-id="4122998069-12">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-14">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="4122998069-15">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="4122998069-15">}</span><span class="p" data-group-id="4122998069-14">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="4122998069-17">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="4122998069-18">[</span><span class="ss">ch_app</span><span class="p" data-group-id="4122998069-18">]</span><span class="p" data-group-id="4122998069-17">}</span><span class="p" data-group-id="4122998069-16">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-19">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="4122998069-20">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="4122998069-20">]</span><span class="p" data-group-id="4122998069-19">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-21">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="4122998069-22">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="4122998069-22">}</span><span class="p" data-group-id="4122998069-21">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-23">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">up</span><span class="p">,</span><span class="p" data-group-id="4122998069-24">[</span><span class="p" data-group-id="4122998069-25">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="4122998069-26">[</span><span class="p" data-group-id="4122998069-26">]</span><span class="p" data-group-id="4122998069-25">}</span><span class="p" data-group-id="4122998069-24">]</span><span class="p" data-group-id="4122998069-23">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-27">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="4122998069-28">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="4122998069-28">]</span><span class="p" data-group-id="4122998069-27">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-29">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="4122998069-30">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">restart_child</span><span class="p">,</span><span class="p" data-group-id="4122998069-31">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="4122998069-31">]</span><span class="p" data-group-id="4122998069-30">}</span><span class="p" data-group-id="4122998069-29">}</span><span class="p" data-group-id="4122998069-5">]</span><span class="p" data-group-id="4122998069-3">}</span><span class="p" data-group-id="4122998069-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="4122998069-32">[</span><span class="p" data-group-id="4122998069-33">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="4122998069-34">[</span><span class="p" data-group-id="4122998069-34">]</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="4122998069-35">[</span><span class="p" data-group-id="4122998069-36">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="4122998069-37">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="4122998069-38">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="4122998069-38">]</span><span class="p" data-group-id="4122998069-37">}</span><span class="p" data-group-id="4122998069-36">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-12">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="6748954964-13">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="6748954964-13">}</span><span class="p" data-group-id="6748954964-12">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-14">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="6748954964-15">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="6748954964-15">}</span><span class="p" data-group-id="6748954964-14">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-16">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="6748954964-17">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="6748954964-18">[</span><span class="ss">ch_app</span><span class="p" data-group-id="6748954964-18">]</span><span class="p" data-group-id="6748954964-17">}</span><span class="p" data-group-id="6748954964-16">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-19">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="6748954964-20">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="6748954964-20">]</span><span class="p" data-group-id="6748954964-19">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-21">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="6748954964-22">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="6748954964-22">}</span><span class="p" data-group-id="6748954964-21">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-23">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">up</span><span class="p">,</span><span class="p" data-group-id="6748954964-24">[</span><span class="p" data-group-id="6748954964-25">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="6748954964-26">[</span><span class="p" data-group-id="6748954964-26">]</span><span class="p" data-group-id="6748954964-25">}</span><span class="p" data-group-id="6748954964-24">]</span><span class="p" data-group-id="6748954964-23">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-27">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="6748954964-28">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="6748954964-28">]</span><span class="p" data-group-id="6748954964-27">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-29">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="6748954964-30">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">restart_child</span><span class="p">,</span><span class="p" data-group-id="6748954964-31">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="6748954964-31">]</span><span class="p" data-group-id="6748954964-30">}</span><span class="p" data-group-id="6748954964-29">}</span><span class="p" data-group-id="6748954964-5">]</span><span class="p" data-group-id="6748954964-3">}</span><span class="p" data-group-id="6748954964-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="6748954964-32">[</span><span class="p" data-group-id="6748954964-33">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="6748954964-34">[</span><span class="p" data-group-id="6748954964-34">]</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="6748954964-35">[</span><span class="p" data-group-id="6748954964-36">{</span><span class="ss">load_object_code</span><span class="p">,</span><span class="p" data-group-id="6748954964-37">{</span><span class="ss">prim_app</span><span class="p">,</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="p" data-group-id="6748954964-38">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="6748954964-38">]</span><span class="p" data-group-id="6748954964-37">}</span><span class="p" data-group-id="6748954964-36">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">point_of_no_return</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-39">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="4122998069-40">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">terminate_child</span><span class="p">,</span><span class="p" data-group-id="4122998069-41">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="4122998069-41">]</span><span class="p" data-group-id="4122998069-40">}</span><span class="p" data-group-id="4122998069-39">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-42">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="4122998069-43">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">delete_child</span><span class="p">,</span><span class="p" data-group-id="4122998069-44">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="4122998069-44">]</span><span class="p" data-group-id="4122998069-43">}</span><span class="p" data-group-id="4122998069-42">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-45">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="4122998069-46">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="4122998069-46">]</span><span class="p" data-group-id="4122998069-45">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-47">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="4122998069-48">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="4122998069-48">}</span><span class="p" data-group-id="4122998069-47">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-49">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">down</span><span class="p">,</span><span class="p" data-group-id="4122998069-50">[</span><span class="p" data-group-id="4122998069-51">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="4122998069-52">[</span><span class="p" data-group-id="4122998069-52">]</span><span class="p" data-group-id="4122998069-51">}</span><span class="p" data-group-id="4122998069-50">]</span><span class="p" data-group-id="4122998069-49">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-53">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="4122998069-54">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="4122998069-54">]</span><span class="p" data-group-id="4122998069-53">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-55">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="4122998069-56">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="4122998069-56">}</span><span class="p" data-group-id="4122998069-55">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-57">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="4122998069-58">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="4122998069-58">}</span><span class="p" data-group-id="4122998069-57">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-59">{</span><span class="ss">purge</span><span class="p">,</span><span class="p" data-group-id="4122998069-60">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="4122998069-60">]</span><span class="p" data-group-id="4122998069-59">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122998069-61">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="4122998069-62">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">unload</span><span class="p">,</span><span class="p" data-group-id="4122998069-63">[</span><span class="ss">ch_app</span><span class="p" data-group-id="4122998069-63">]</span><span class="p" data-group-id="4122998069-62">}</span><span class="p" data-group-id="4122998069-61">}</span><span class="p" data-group-id="4122998069-35">]</span><span class="p" data-group-id="4122998069-33">}</span><span class="p" data-group-id="4122998069-32">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4122998069-1">}</span><span class="p">.</span></code></pre><h2 id="changing-non-erlang-code" class="section-heading">
│ │ │ +    </span><span class="p" data-group-id="6748954964-39">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="6748954964-40">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">terminate_child</span><span class="p">,</span><span class="p" data-group-id="6748954964-41">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="6748954964-41">]</span><span class="p" data-group-id="6748954964-40">}</span><span class="p" data-group-id="6748954964-39">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-42">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="6748954964-43">{</span><span class="ss">supervisor</span><span class="p">,</span><span class="ss">delete_child</span><span class="p">,</span><span class="p" data-group-id="6748954964-44">[</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">ch_sup</span><span class="p" data-group-id="6748954964-44">]</span><span class="p" data-group-id="6748954964-43">}</span><span class="p" data-group-id="6748954964-42">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-45">{</span><span class="ss">suspend</span><span class="p">,</span><span class="p" data-group-id="6748954964-46">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="6748954964-46">]</span><span class="p" data-group-id="6748954964-45">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-47">{</span><span class="ss">load</span><span class="p">,</span><span class="p" data-group-id="6748954964-48">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="6748954964-48">}</span><span class="p" data-group-id="6748954964-47">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-49">{</span><span class="ss">code_change</span><span class="p">,</span><span class="ss">down</span><span class="p">,</span><span class="p" data-group-id="6748954964-50">[</span><span class="p" data-group-id="6748954964-51">{</span><span class="ss">prim_sup</span><span class="p">,</span><span class="p" data-group-id="6748954964-52">[</span><span class="p" data-group-id="6748954964-52">]</span><span class="p" data-group-id="6748954964-51">}</span><span class="p" data-group-id="6748954964-50">]</span><span class="p" data-group-id="6748954964-49">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-53">{</span><span class="ss">resume</span><span class="p">,</span><span class="p" data-group-id="6748954964-54">[</span><span class="ss">prim_sup</span><span class="p" data-group-id="6748954964-54">]</span><span class="p" data-group-id="6748954964-53">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-55">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="6748954964-56">{</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="6748954964-56">}</span><span class="p" data-group-id="6748954964-55">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-57">{</span><span class="ss">remove</span><span class="p">,</span><span class="p" data-group-id="6748954964-58">{</span><span class="ss">ch3</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p">,</span><span class="ss">brutal_purge</span><span class="p" data-group-id="6748954964-58">}</span><span class="p" data-group-id="6748954964-57">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-59">{</span><span class="ss">purge</span><span class="p">,</span><span class="p" data-group-id="6748954964-60">[</span><span class="ss">ch_sup</span><span class="p">,</span><span class="ss">ch3</span><span class="p" data-group-id="6748954964-60">]</span><span class="p" data-group-id="6748954964-59">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6748954964-61">{</span><span class="nb">apply</span><span class="p">,</span><span class="p" data-group-id="6748954964-62">{</span><span class="ss">application</span><span class="p">,</span><span class="ss">unload</span><span class="p">,</span><span class="p" data-group-id="6748954964-63">[</span><span class="ss">ch_app</span><span class="p" data-group-id="6748954964-63">]</span><span class="p" data-group-id="6748954964-62">}</span><span class="p" data-group-id="6748954964-61">}</span><span class="p" data-group-id="6748954964-35">]</span><span class="p" data-group-id="6748954964-33">}</span><span class="p" data-group-id="6748954964-32">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6748954964-1">}</span><span class="p">.</span></code></pre><h2 id="changing-non-erlang-code" class="section-heading">
│ │ │    <a href="#changing-non-erlang-code" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Changing Non-Erlang Code</span>
│ │ │  </h2>
│ │ │  <p>Changing code for a program written in another programming language than Erlang,
│ │ │  for example, a port program, is application-dependent and OTP provides no
│ │ │  special support.</p><p><em>Example</em></p><p>When changing code for a port program, assume that the Erlang process
│ │ │  controlling the port is a <code class="inline">gen_server</code> <code class="inline">portc</code> and that the port is opened in
│ │ │ -the callback function <code class="inline">init/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="4545785843-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4545785843-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +the callback function <code class="inline">init/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0573310705-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0573310705-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4545785843-2">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="4545785843-3">(</span><span class="n">App</span><span class="p" data-group-id="4545785843-3">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="4545785843-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="4545785843-4">(</span><span class="p" data-group-id="4545785843-5">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="4545785843-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4545785843-6">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4545785843-6">]</span><span class="p" data-group-id="4545785843-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="0573310705-2">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="0573310705-3">(</span><span class="n">App</span><span class="p" data-group-id="0573310705-3">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="0573310705-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="0573310705-4">(</span><span class="p" data-group-id="0573310705-5">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="0573310705-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0573310705-6">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0573310705-6">]</span><span class="p" data-group-id="0573310705-4">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4545785843-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="4545785843-8">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4545785843-8">}</span><span class="p" data-group-id="4545785843-7">}</span><span class="p">.</span></code></pre><p>If the port program is to be updated, the code for the <code class="inline">gen_server</code> can be
│ │ │ +    </span><span class="p" data-group-id="0573310705-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="0573310705-8">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0573310705-8">}</span><span class="p" data-group-id="0573310705-7">}</span><span class="p">.</span></code></pre><p>If the port program is to be updated, the code for the <code class="inline">gen_server</code> can be
│ │ │  extended with a <code class="inline">code_change/3</code> function, which closes the old port and opens a
│ │ │  new port. (If necessary, the <code class="inline">gen_server</code> can first request data that must be
│ │ │ -saved from the port program and pass this data to the new port):</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="7531774448-1">(</span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="ss">port</span><span class="p" data-group-id="7531774448-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +saved from the port program and pass this data to the new port):</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="7087429657-1">(</span><span class="p">_</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="ss">port</span><span class="p" data-group-id="7087429657-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">close</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7531774448-2">{</span><span class="n">Port</span><span class="p">,</span><span class="ss">close</span><span class="p" data-group-id="7531774448-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="7087429657-2">{</span><span class="n">Port</span><span class="p">,</span><span class="ss">close</span><span class="p" data-group-id="7087429657-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="7531774448-3">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="7531774448-4">(</span><span class="n">App</span><span class="p" data-group-id="7531774448-4">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="7531774448-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="7531774448-5">(</span><span class="p" data-group-id="7531774448-6">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="7531774448-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7531774448-7">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7531774448-7">]</span><span class="p" data-group-id="7531774448-5">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7531774448-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="7531774448-9">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7531774448-9">}</span><span class="p" data-group-id="7531774448-8">}</span><span class="p">.</span></code></pre><p>Update the application version number in the <code class="inline">.app</code> file and write an <code class="inline">.appup</code>
│ │ │ -file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6364736468-1">[</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="6364736468-2">[</span><span class="p" data-group-id="6364736468-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6364736468-4">[</span><span class="p" data-group-id="6364736468-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6364736468-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="6364736468-6">}</span><span class="p" data-group-id="6364736468-5">}</span><span class="p" data-group-id="6364736468-4">]</span><span class="p" data-group-id="6364736468-3">}</span><span class="p" data-group-id="6364736468-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="6364736468-7">[</span><span class="p" data-group-id="6364736468-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6364736468-9">[</span><span class="p" data-group-id="6364736468-10">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6364736468-11">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="6364736468-11">}</span><span class="p" data-group-id="6364736468-10">}</span><span class="p" data-group-id="6364736468-9">]</span><span class="p" data-group-id="6364736468-8">}</span><span class="p" data-group-id="6364736468-7">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6364736468-1">]</span><span class="p">.</span></code></pre><p>Ensure that the <code class="inline">priv</code> directory, where the C program is located, is included in
│ │ │ -the new release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="0350629539-1">(</span><span class="s">&quot;my_release&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0350629539-2">[</span><span class="p" data-group-id="0350629539-3">{</span><span class="ss">dirs</span><span class="p">,</span><span class="p" data-group-id="0350629539-4">[</span><span class="ss">priv</span><span class="p" data-group-id="0350629539-4">]</span><span class="p" data-group-id="0350629539-3">}</span><span class="p" data-group-id="0350629539-2">]</span><span class="p" data-group-id="0350629539-1">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="n">PortPrg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="7087429657-3">(</span><span class="nc">code</span><span class="p">:</span><span class="nf">priv_dir</span><span class="p" data-group-id="7087429657-4">(</span><span class="n">App</span><span class="p" data-group-id="7087429657-4">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;portc&quot;</span><span class="p" data-group-id="7087429657-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="7087429657-5">(</span><span class="p" data-group-id="7087429657-6">{</span><span class="nb">spawn</span><span class="p">,</span><span class="n">PortPrg</span><span class="p" data-group-id="7087429657-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7087429657-7">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7087429657-7">]</span><span class="p" data-group-id="7087429657-5">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7087429657-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="7087429657-9">{</span><span class="ss">port</span><span class="o">=</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7087429657-9">}</span><span class="p" data-group-id="7087429657-8">}</span><span class="p">.</span></code></pre><p>Update the application version number in the <code class="inline">.app</code> file and write an <code class="inline">.appup</code>
│ │ │ +file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4164617685-1">[</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="4164617685-2">[</span><span class="p" data-group-id="4164617685-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4164617685-4">[</span><span class="p" data-group-id="4164617685-5">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4164617685-6">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="4164617685-6">}</span><span class="p" data-group-id="4164617685-5">}</span><span class="p" data-group-id="4164617685-4">]</span><span class="p" data-group-id="4164617685-3">}</span><span class="p" data-group-id="4164617685-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="4164617685-7">[</span><span class="p" data-group-id="4164617685-8">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4164617685-9">[</span><span class="p" data-group-id="4164617685-10">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="ss">portc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4164617685-11">{</span><span class="ss">advanced</span><span class="p">,</span><span class="ss">port</span><span class="p" data-group-id="4164617685-11">}</span><span class="p" data-group-id="4164617685-10">}</span><span class="p" data-group-id="4164617685-9">]</span><span class="p" data-group-id="4164617685-8">}</span><span class="p" data-group-id="4164617685-7">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4164617685-1">]</span><span class="p">.</span></code></pre><p>Ensure that the <code class="inline">priv</code> directory, where the C program is located, is included in
│ │ │ +the new release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="7507103794-1">(</span><span class="s">&quot;my_release&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7507103794-2">[</span><span class="p" data-group-id="7507103794-3">{</span><span class="ss">dirs</span><span class="p">,</span><span class="p" data-group-id="7507103794-4">[</span><span class="ss">priv</span><span class="p" data-group-id="7507103794-4">]</span><span class="p" data-group-id="7507103794-3">}</span><span class="p" data-group-id="7507103794-2">]</span><span class="p" data-group-id="7507103794-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="runtime-system-restart-and-upgrade" class="section-heading">
│ │ │    <a href="#runtime-system-restart-and-upgrade" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Runtime System Restart and Upgrade</span>
│ │ │  </h2>
│ │ │  <p>Two upgrade instructions restart the runtime system:</p><ul><li><p><code class="inline">restart_new_emulator</code></p><p>Intended when ERTS, Kernel, STDLIB, or SASL is upgraded. It is automatically
│ │ │ @@ -555,22 +555,22 @@
│ │ │  executed before all other upgrade instructions. For more information about
│ │ │  this instruction, see restart_new_emulator (Low-Level) in
│ │ │  <a href="release_handling.html#restart_new_emulator_instr">Release Handling Instructions</a>.</p></li><li><p><code class="inline">restart_emulator</code></p><p>Used when a restart of the runtime system is required after all other upgrade
│ │ │  instructions are executed. For more information about this instruction, see
│ │ │  restart_emulator (Low-Level) in
│ │ │  <a href="release_handling.html#restart_emulator_instr">Release Handling Instructions</a>.</p></li></ul><p>If a runtime system restart is necessary and no upgrade instructions are needed,
│ │ │  that is, if the restart itself is enough for the upgraded applications to start
│ │ │ -running the new versions, a simple <code class="inline">.relup</code> file can be created manually:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5694369822-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5694369822-2">[</span><span class="p" data-group-id="5694369822-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="5694369822-4">[</span><span class="p" data-group-id="5694369822-4">]</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="5694369822-5">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="5694369822-5">]</span><span class="p" data-group-id="5694369822-3">}</span><span class="p" data-group-id="5694369822-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5694369822-6">[</span><span class="p" data-group-id="5694369822-7">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="5694369822-8">[</span><span class="p" data-group-id="5694369822-8">]</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="5694369822-9">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="5694369822-9">]</span><span class="p" data-group-id="5694369822-7">}</span><span class="p" data-group-id="5694369822-6">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5694369822-1">}</span><span class="p">.</span></code></pre><p>In this case, the release handler framework with automatic packing and unpacking
│ │ │ +running the new versions, a simple <code class="inline">.relup</code> file can be created manually:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5241576341-1">{</span><span class="s">&quot;B&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5241576341-2">[</span><span class="p" data-group-id="5241576341-3">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="5241576341-4">[</span><span class="p" data-group-id="5241576341-4">]</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="5241576341-5">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="5241576341-5">]</span><span class="p" data-group-id="5241576341-3">}</span><span class="p" data-group-id="5241576341-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5241576341-6">[</span><span class="p" data-group-id="5241576341-7">{</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="5241576341-8">[</span><span class="p" data-group-id="5241576341-8">]</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="5241576341-9">[</span><span class="ss">restart_emulator</span><span class="p" data-group-id="5241576341-9">]</span><span class="p" data-group-id="5241576341-7">}</span><span class="p" data-group-id="5241576341-6">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5241576341-1">}</span><span class="p">.</span></code></pre><p>In this case, the release handler framework with automatic packing and unpacking
│ │ │  of release packages, automatic path updates, and so on, can be used without
│ │ │  having to specify <code class="inline">.appup</code> files.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/benchmarking.html
│ │ │ @@ -144,16 +144,16 @@
│ │ │  fast as possible, what can we do? One way could be to generate more
│ │ │  than two bytes at the time.</p><pre><code class="text">% erlperf 'rand:bytes(100).' 'crypto:strong_rand_bytes(100).'
│ │ │  Code                                   ||        QPS       Time   Rel
│ │ │  rand:bytes(100).                        1    2124 Ki     470 ns  100%
│ │ │  crypto:strong_rand_bytes(100).          1    1915 Ki     522 ns   90%</code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/rand.html#bytes/1"><code class="inline">rand:bytes/1</code></a> is still faster when we generate 100 bytes at the time,
│ │ │  but the relative difference is smaller.</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erlperf &#39;rand:bytes(1000).&#39; &#39;crypto:strong_rand_bytes(1000).&#39;</span><span class="w">
│ │ │  </span><span class="n">Code</span><span class="w">                                    </span><span class="p">||</span><span class="w">        </span><span class="n">QPS</span><span class="w">       </span><span class="n">Time</span><span class="w">   </span><span class="n">Rel</span><span class="w">
│ │ │ -</span><span class="nc">crypto</span><span class="p">:</span><span class="nf">strong_rand_bytes</span><span class="p" data-group-id="6500574989-1">(</span><span class="mi">1000</span><span class="p" data-group-id="6500574989-1">)</span><span class="p">.</span><span class="w">          </span><span class="mi">1</span><span class="w">    </span><span class="mi">1518</span><span class="w"> </span><span class="n">Ki</span><span class="w">     </span><span class="mi">658</span><span class="w"> </span><span class="ss">ns</span><span class="w">  </span><span class="mi">100</span><span class="c1">%</span><span class="w">
│ │ │ -</span><span class="nc">rand</span><span class="p">:</span><span class="nf">bytes</span><span class="p" data-group-id="6500574989-2">(</span><span class="mi">1000</span><span class="p" data-group-id="6500574989-2">)</span><span class="p">.</span><span class="w">                        </span><span class="mi">1</span><span class="w">     </span><span class="mi">284</span><span class="w"> </span><span class="n">Ki</span><span class="w">    </span><span class="mi">3521</span><span class="w"> </span><span class="ss">ns</span><span class="w">   </span><span class="mi">19</span><span class="c1">%</span></code></pre><p>When we generate 1000 bytes at the time, <a href="../../lib/crypto-5.5.3/doc/html/crypto.html#strong_rand_bytes/1"><code class="inline">crypto:strong_rand_bytes/1</code></a> is
│ │ │ +</span><span class="nc">crypto</span><span class="p">:</span><span class="nf">strong_rand_bytes</span><span class="p" data-group-id="8674283558-1">(</span><span class="mi">1000</span><span class="p" data-group-id="8674283558-1">)</span><span class="p">.</span><span class="w">          </span><span class="mi">1</span><span class="w">    </span><span class="mi">1518</span><span class="w"> </span><span class="n">Ki</span><span class="w">     </span><span class="mi">658</span><span class="w"> </span><span class="ss">ns</span><span class="w">  </span><span class="mi">100</span><span class="c1">%</span><span class="w">
│ │ │ +</span><span class="nc">rand</span><span class="p">:</span><span class="nf">bytes</span><span class="p" data-group-id="8674283558-2">(</span><span class="mi">1000</span><span class="p" data-group-id="8674283558-2">)</span><span class="p">.</span><span class="w">                        </span><span class="mi">1</span><span class="w">     </span><span class="mi">284</span><span class="w"> </span><span class="n">Ki</span><span class="w">    </span><span class="mi">3521</span><span class="w"> </span><span class="ss">ns</span><span class="w">   </span><span class="mi">19</span><span class="c1">%</span></code></pre><p>When we generate 1000 bytes at the time, <a href="../../lib/crypto-5.5.3/doc/html/crypto.html#strong_rand_bytes/1"><code class="inline">crypto:strong_rand_bytes/1</code></a> is
│ │ │  now the fastest.</p><h2 id="benchmarking-using-erlang-otp-functionality" class="section-heading">
│ │ │    <a href="#benchmarking-using-erlang-otp-functionality" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Benchmarking using Erlang/OTP functionality</span>
│ │ │  </h2>
│ │ │  <p>Benchmarks can measure wall-clock time or CPU time.</p><ul><li><p><a href="../../lib/stdlib-6.2.2.2/doc/html/timer.html#tc/3"><code class="inline">timer:tc/3</code></a> measures wall-clock time. The advantage with wall-clock time is
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/binaryhandling.html
│ │ │ @@ -114,43 +114,43 @@
│ │ │  
│ │ │      <span>Constructing and Matching Binaries</span>
│ │ │    </h1>
│ │ │  
│ │ │  <p>This section gives a few examples on how to handle binaries in an efficient way.
│ │ │  The sections that follow take an in-depth look at how binaries are implemented
│ │ │  and how to best take advantages of the optimizations done by the compiler and
│ │ │ -runtime system.</p><p>Binaries can be efficiently <em>built</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_list_to_binary</span><span class="p" data-group-id="6351074092-1">(</span><span class="n">List</span><span class="p" data-group-id="6351074092-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="6351074092-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6351074092-3">&lt;&lt;</span><span class="p" data-group-id="6351074092-3">&gt;&gt;</span><span class="p" data-group-id="6351074092-2">)</span><span class="p">.</span><span class="w">
│ │ │ +runtime system.</p><p>Binaries can be efficiently <em>built</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_list_to_binary</span><span class="p" data-group-id="7407634916-1">(</span><span class="n">List</span><span class="p" data-group-id="7407634916-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="7407634916-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7407634916-3">&lt;&lt;</span><span class="p" data-group-id="7407634916-3">&gt;&gt;</span><span class="p" data-group-id="7407634916-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="6351074092-4">(</span><span class="p" data-group-id="6351074092-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6351074092-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6351074092-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="6351074092-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6351074092-7">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="6351074092-7">&gt;&gt;</span><span class="p" data-group-id="6351074092-6">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="6351074092-8">(</span><span class="p" data-group-id="6351074092-9">[</span><span class="p" data-group-id="6351074092-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6351074092-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="7407634916-4">(</span><span class="p" data-group-id="7407634916-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7407634916-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7407634916-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="7407634916-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7407634916-7">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="7407634916-7">&gt;&gt;</span><span class="p" data-group-id="7407634916-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">my_list_to_binary</span><span class="p" data-group-id="7407634916-8">(</span><span class="p" data-group-id="7407634916-9">[</span><span class="p" data-group-id="7407634916-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7407634916-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Appending data to a binary as in the example is efficient because it is
│ │ │  specially optimized by the runtime system to avoid copying the <code class="inline">Acc</code> binary
│ │ │ -every time.</p><p>Prepending data to a binary in a loop is not efficient:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6318937723-1">(</span><span class="n">List</span><span class="p" data-group-id="6318937723-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6318937723-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6318937723-3">&lt;&lt;</span><span class="p" data-group-id="6318937723-3">&gt;&gt;</span><span class="p" data-group-id="6318937723-2">)</span><span class="p">.</span><span class="w">
│ │ │ +every time.</p><p>Prepending data to a binary in a loop is not efficient:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7710606116-1">(</span><span class="n">List</span><span class="p" data-group-id="7710606116-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7710606116-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7710606116-3">&lt;&lt;</span><span class="p" data-group-id="7710606116-3">&gt;&gt;</span><span class="p" data-group-id="7710606116-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6318937723-4">(</span><span class="p" data-group-id="6318937723-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6318937723-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6318937723-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6318937723-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6318937723-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6318937723-7">&gt;&gt;</span><span class="p" data-group-id="6318937723-6">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6318937723-8">(</span><span class="p" data-group-id="6318937723-9">[</span><span class="p" data-group-id="6318937723-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6318937723-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7710606116-4">(</span><span class="p" data-group-id="7710606116-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7710606116-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7710606116-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7710606116-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7710606116-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7710606116-7">&gt;&gt;</span><span class="p" data-group-id="7710606116-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7710606116-8">(</span><span class="p" data-group-id="7710606116-9">[</span><span class="p" data-group-id="7710606116-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7710606116-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>This is not efficient for long lists because the <code class="inline">Acc</code> binary is copied every
│ │ │ -time. One way to make the function more efficient is like this:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7367127324-1">(</span><span class="n">List</span><span class="p" data-group-id="7367127324-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7367127324-2">(</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="7367127324-3">(</span><span class="n">List</span><span class="p" data-group-id="7367127324-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7367127324-4">&lt;&lt;</span><span class="p" data-group-id="7367127324-4">&gt;&gt;</span><span class="p" data-group-id="7367127324-2">)</span><span class="p">.</span><span class="w">
│ │ │ +time. One way to make the function more efficient is like this:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6176950266-1">(</span><span class="n">List</span><span class="p" data-group-id="6176950266-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6176950266-2">(</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="6176950266-3">(</span><span class="n">List</span><span class="p" data-group-id="6176950266-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6176950266-4">&lt;&lt;</span><span class="p" data-group-id="6176950266-4">&gt;&gt;</span><span class="p" data-group-id="6176950266-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7367127324-5">(</span><span class="p" data-group-id="7367127324-6">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7367127324-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7367127324-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7367127324-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7367127324-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="7367127324-8">&gt;&gt;</span><span class="p" data-group-id="7367127324-7">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="7367127324-9">(</span><span class="p" data-group-id="7367127324-10">[</span><span class="p" data-group-id="7367127324-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7367127324-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Another way to avoid copying the binary each time is like this:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0395710078-1">(</span><span class="p" data-group-id="0395710078-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0395710078-2">]</span><span class="p" data-group-id="0395710078-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">RevTail</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0395710078-3">(</span><span class="n">T</span><span class="p" data-group-id="0395710078-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0395710078-4">&lt;&lt;</span><span class="n">RevTail</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="0395710078-4">&gt;&gt;</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="0395710078-5">(</span><span class="p" data-group-id="0395710078-6">[</span><span class="p" data-group-id="0395710078-6">]</span><span class="p" data-group-id="0395710078-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0395710078-7">&lt;&lt;</span><span class="p" data-group-id="0395710078-7">&gt;&gt;</span><span class="p">.</span></code></pre><p>Note that in each of the <strong>DO</strong> examples, the binary to be appended to is always
│ │ │ -given as the first segment.</p><p>Binaries can be efficiently <em>matched</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="1667876199-1">(</span><span class="p" data-group-id="1667876199-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="1667876199-2">&gt;&gt;</span><span class="p" data-group-id="1667876199-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1667876199-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="1667876199-4">(</span><span class="n">T</span><span class="p" data-group-id="1667876199-4">)</span><span class="p" data-group-id="1667876199-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="1667876199-5">(</span><span class="p" data-group-id="1667876199-6">&lt;&lt;</span><span class="p" data-group-id="1667876199-6">&gt;&gt;</span><span class="p" data-group-id="1667876199-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1667876199-7">[</span><span class="p" data-group-id="1667876199-7">]</span><span class="p">.</span></code></pre><h2 id="how-binaries-are-implemented" class="section-heading">
│ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6176950266-5">(</span><span class="p" data-group-id="6176950266-6">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6176950266-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6176950266-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6176950266-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6176950266-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="6176950266-8">&gt;&gt;</span><span class="p" data-group-id="6176950266-7">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6176950266-9">(</span><span class="p" data-group-id="6176950266-10">[</span><span class="p" data-group-id="6176950266-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6176950266-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Another way to avoid copying the binary each time is like this:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6910424358-1">(</span><span class="p" data-group-id="6910424358-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6910424358-2">]</span><span class="p" data-group-id="6910424358-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">RevTail</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6910424358-3">(</span><span class="n">T</span><span class="p" data-group-id="6910424358-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6910424358-4">&lt;&lt;</span><span class="n">RevTail</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">H</span><span class="p" data-group-id="6910424358-4">&gt;&gt;</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">rev_list_to_binary</span><span class="p" data-group-id="6910424358-5">(</span><span class="p" data-group-id="6910424358-6">[</span><span class="p" data-group-id="6910424358-6">]</span><span class="p" data-group-id="6910424358-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6910424358-7">&lt;&lt;</span><span class="p" data-group-id="6910424358-7">&gt;&gt;</span><span class="p">.</span></code></pre><p>Note that in each of the <strong>DO</strong> examples, the binary to be appended to is always
│ │ │ +given as the first segment.</p><p>Binaries can be efficiently <em>matched</em> in the following way:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="3678273442-1">(</span><span class="p" data-group-id="3678273442-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3678273442-2">&gt;&gt;</span><span class="p" data-group-id="3678273442-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3678273442-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="3678273442-4">(</span><span class="n">T</span><span class="p" data-group-id="3678273442-4">)</span><span class="p" data-group-id="3678273442-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="3678273442-5">(</span><span class="p" data-group-id="3678273442-6">&lt;&lt;</span><span class="p" data-group-id="3678273442-6">&gt;&gt;</span><span class="p" data-group-id="3678273442-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3678273442-7">[</span><span class="p" data-group-id="3678273442-7">]</span><span class="p">.</span></code></pre><h2 id="how-binaries-are-implemented" class="section-heading">
│ │ │    <a href="#how-binaries-are-implemented" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">How Binaries are Implemented</span>
│ │ │  </h2>
│ │ │  <p>Internally, binaries and bitstrings are implemented in the same way. In this
│ │ │  section, they are called <em>binaries</em> because that is what they are called in the
│ │ │ @@ -205,29 +205,29 @@
│ │ │  called referential transparency) of Erlang would break.</p><h2 id="constructing-binaries" class="section-heading">
│ │ │    <a href="#constructing-binaries" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Constructing Binaries</span>
│ │ │  </h2>
│ │ │  <p>Appending to a binary or bitstring in the following way is specially optimized
│ │ │ -to avoid copying the binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9782306295-1">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9782306295-1">&gt;&gt;</span><span class="w">
│ │ │ +to avoid copying the binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3190724234-1">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3190724234-1">&gt;&gt;</span><span class="w">
│ │ │  </span><span class="c1">%% - OR -</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9782306295-2">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">bitstring</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9782306295-2">&gt;&gt;</span></code></pre><p>This optimization is applied by the runtime system in a way that makes it
│ │ │ +</span><span class="p" data-group-id="3190724234-2">&lt;&lt;</span><span class="n">Binary</span><span class="o">/</span><span class="ss">bitstring</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3190724234-2">&gt;&gt;</span></code></pre><p>This optimization is applied by the runtime system in a way that makes it
│ │ │  effective in most circumstances (for exceptions, see
│ │ │  <a href="binaryhandling.html#forced_copying">Circumstances That Force Copying</a>). The
│ │ │  optimization in its basic form does not need any help from the compiler.
│ │ │  However, the compiler add hints to the runtime system when it is safe to apply
│ │ │  the optimization in a more efficient way.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>The compiler support for making the optimization more efficient was added in
│ │ │  Erlang/OTP 26.</p></section><p>To explain how the basic optimization works, let us examine the following code
│ │ │ -line by line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3309401692-1">&lt;&lt;</span><span class="mi">0</span><span class="p" data-group-id="3309401692-1">&gt;&gt;</span><span class="p">,</span><span class="w">                    </span><span class="c1">%% 1</span><span class="w">
│ │ │ -</span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3309401692-2">&lt;&lt;</span><span class="n">Bin0</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3309401692-2">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 2</span><span class="w">
│ │ │ -</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3309401692-3">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3309401692-3">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 3</span><span class="w">
│ │ │ -</span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3309401692-4">&lt;&lt;</span><span class="n">Bin2</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p" data-group-id="3309401692-4">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 4</span><span class="w">
│ │ │ -</span><span class="n">Bin4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3309401692-5">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="3309401692-5">&gt;&gt;</span><span class="p">,</span><span class="w">       </span><span class="c1">%% 5 !!!</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3309401692-6">{</span><span class="n">Bin4</span><span class="p">,</span><span class="n">Bin3</span><span class="p" data-group-id="3309401692-6">}</span><span class="w">                      </span><span class="c1">%% 6</span></code></pre><ul><li><p>Line 1 (marked with the <code class="inline">%% 1</code> comment), assigns a
│ │ │ +line by line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2871410741-1">&lt;&lt;</span><span class="mi">0</span><span class="p" data-group-id="2871410741-1">&gt;&gt;</span><span class="p">,</span><span class="w">                    </span><span class="c1">%% 1</span><span class="w">
│ │ │ +</span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2871410741-2">&lt;&lt;</span><span class="n">Bin0</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2871410741-2">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 2</span><span class="w">
│ │ │ +</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2871410741-3">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2871410741-3">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 3</span><span class="w">
│ │ │ +</span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2871410741-4">&lt;&lt;</span><span class="n">Bin2</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p" data-group-id="2871410741-4">&gt;&gt;</span><span class="p">,</span><span class="w">    </span><span class="c1">%% 4</span><span class="w">
│ │ │ +</span><span class="n">Bin4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2871410741-5">&lt;&lt;</span><span class="n">Bin1</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="2871410741-5">&gt;&gt;</span><span class="p">,</span><span class="w">       </span><span class="c1">%% 5 !!!</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2871410741-6">{</span><span class="n">Bin4</span><span class="p">,</span><span class="n">Bin3</span><span class="p" data-group-id="2871410741-6">}</span><span class="w">                      </span><span class="c1">%% 6</span></code></pre><ul><li><p>Line 1 (marked with the <code class="inline">%% 1</code> comment), assigns a
│ │ │  <a href="binaryhandling.html#heap_binary">heap binary</a> to the <code class="inline">Bin0</code> variable.</p></li><li><p>Line 2 is an append operation. As <code class="inline">Bin0</code> has not been involved in an append
│ │ │  operation, a new <a href="binaryhandling.html#refc_binary">refc binary</a> is created and
│ │ │  the contents of <code class="inline">Bin0</code> is copied into it. The <em>ProcBin</em> part of the refc
│ │ │  binary has its size set to the size of the data stored in the binary, while
│ │ │  the binary object has extra space allocated. The size of the binary object is
│ │ │  either twice the size of <code class="inline">Bin1</code> or 256, whichever is larger. In this case it
│ │ │  is 256.</p></li><li><p>Line 3 is more interesting. <code class="inline">Bin1</code> <em>has</em> been used in an append operation, and
│ │ │ @@ -253,23 +253,23 @@
│ │ │  handle an append operation to a heap binary by copying it to a refc binary (line
│ │ │  2), and also handle an append operation to a previous version of the binary by
│ │ │  copying it (line 5). The support for doing that does not come for free. For
│ │ │  example, to make it possible to know when it is necessary to copy the binary,
│ │ │  for every append operation, the runtime system must create a sub binary.</p><p>When the compiler can determine that none of those situations need to be handled
│ │ │  and that the append operation cannot possibly fail, the compiler generates code
│ │ │  that causes the runtime system to apply a more efficient variant of the
│ │ │ -optimization.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7060453671-1">(</span><span class="ss">repack</span><span class="p" data-group-id="7060453671-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7060453671-2">(</span><span class="p" data-group-id="7060453671-3">[</span><span class="ss">repack</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7060453671-3">]</span><span class="p" data-group-id="7060453671-2">)</span><span class="p">.</span><span class="w">
│ │ │ +optimization.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2444437743-1">(</span><span class="ss">repack</span><span class="p" data-group-id="2444437743-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2444437743-2">(</span><span class="p" data-group-id="2444437743-3">[</span><span class="ss">repack</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2444437743-3">]</span><span class="p" data-group-id="2444437743-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">repack</span><span class="p" data-group-id="7060453671-4">(</span><span class="n">Bin</span><span class="p" data-group-id="7060453671-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_binary</span><span class="p" data-group-id="7060453671-5">(</span><span class="n">Bin</span><span class="p" data-group-id="7060453671-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">repack</span><span class="p" data-group-id="7060453671-6">(</span><span class="n">Bin</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7060453671-7">&lt;&lt;</span><span class="p" data-group-id="7060453671-7">&gt;&gt;</span><span class="p" data-group-id="7060453671-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">repack</span><span class="p" data-group-id="2444437743-4">(</span><span class="n">Bin</span><span class="p" data-group-id="2444437743-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_binary</span><span class="p" data-group-id="2444437743-5">(</span><span class="n">Bin</span><span class="p" data-group-id="2444437743-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">repack</span><span class="p" data-group-id="2444437743-6">(</span><span class="n">Bin</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2444437743-7">&lt;&lt;</span><span class="p" data-group-id="2444437743-7">&gt;&gt;</span><span class="p" data-group-id="2444437743-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">repack</span><span class="p" data-group-id="7060453671-8">(</span><span class="p" data-group-id="7060453671-9">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7060453671-9">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7060453671-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">repack</span><span class="p" data-group-id="7060453671-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7060453671-11">&lt;&lt;</span><span class="n">Result</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="7060453671-11">&gt;&gt;</span><span class="p" data-group-id="7060453671-10">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">repack</span><span class="p" data-group-id="7060453671-12">(</span><span class="p" data-group-id="7060453671-13">&lt;&lt;</span><span class="p" data-group-id="7060453671-13">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7060453671-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">repack</span><span class="p" data-group-id="2444437743-8">(</span><span class="p" data-group-id="2444437743-9">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2444437743-9">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="2444437743-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">repack</span><span class="p" data-group-id="2444437743-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2444437743-11">&lt;&lt;</span><span class="n">Result</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="2444437743-11">&gt;&gt;</span><span class="p" data-group-id="2444437743-10">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">repack</span><span class="p" data-group-id="2444437743-12">(</span><span class="p" data-group-id="2444437743-13">&lt;&lt;</span><span class="p" data-group-id="2444437743-13">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="2444437743-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Result</span><span class="p">.</span></code></pre><p>The <code class="inline">repack/2</code> function only keeps a single version of the binary, so there is
│ │ │  never any need to copy the binary. The compiler rewrites the creation of the
│ │ │  empty binary in <code class="inline">repack/1</code> to instead create a refc binary with 256 bytes
│ │ │  already reserved; thus, the append operation in <code class="inline">repack/2</code> never needs to handle
│ │ │  a binary not prepared for appending.</p><p><a href="" id="forced_copying"></a></p><h3 id="circumstances-that-force-copying" class="section-heading">
│ │ │    <a href="#circumstances-that-force-copying" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -281,72 +281,72 @@
│ │ │  reason is that the binary object can be moved (reallocated) during an append
│ │ │  operation, and when that happens, the pointer in the ProcBin must be updated. If
│ │ │  there would be more than one ProcBin pointing to the binary object, it would not
│ │ │  be possible to find and update all of them.</p><p>Therefore, certain operations on a binary mark it so that any future append
│ │ │  operation will be forced to copy the binary. In most cases, the binary object
│ │ │  will be shrunk at the same time to reclaim the extra space allocated for
│ │ │  growing.</p><p>When appending to a binary as follows, only the binary returned from the latest
│ │ │ -append operation will support further cheap append operations:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3458571910-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3458571910-1">&gt;&gt;</span></code></pre><p>In the code fragment in the beginning of this section, appending to <code class="inline">Bin</code> will
│ │ │ +append operation will support further cheap append operations:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7589280343-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7589280343-1">&gt;&gt;</span></code></pre><p>In the code fragment in the beginning of this section, appending to <code class="inline">Bin</code> will
│ │ │  be cheap, while appending to <code class="inline">Bin0</code> will force the creation of a new binary and
│ │ │  copying of the contents of <code class="inline">Bin0</code>.</p><p>If a binary is sent as a message to a process or port, the binary will be shrunk
│ │ │  and any further append operation will copy the binary data into a new binary.
│ │ │  For example, in the following code fragment <code class="inline">Bin1</code> will be copied in the third
│ │ │ -line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4758790600-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4758790600-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ +line:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9753625537-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9753625537-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="n">PortOrPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Bin1</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4758790600-2">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4758790600-2">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The same happens if you insert a binary into an Ets table, send it to a port
│ │ │ +</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9753625537-2">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="9753625537-2">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The same happens if you insert a binary into an Ets table, send it to a port
│ │ │  using <a href="../../erts-15.2.7.3/doc/html/erlang.html#port_command/2"><code class="inline">erlang:port_command/2</code></a>, or pass it to
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erl_nif.html#enif_inspect_binary">enif_inspect_binary</a> in a NIF.</p><p>Matching a binary will also cause it to shrink and the next append operation
│ │ │ -will copy the binary data:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5009492084-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5009492084-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5009492084-2">&lt;&lt;</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5009492084-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin1</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5009492084-3">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5009492084-3">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The reason is that a <a href="binaryhandling.html#match_context">match context</a> contains a
│ │ │ +will copy the binary data:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3922371508-1">&lt;&lt;</span><span class="n">Bin0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3922371508-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3922371508-2">&lt;&lt;</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3922371508-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin1</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3922371508-3">&lt;&lt;</span><span class="n">Bin1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3922371508-3">&gt;&gt;</span><span class="w">  </span><span class="c1">%% Bin1 will be COPIED</span></code></pre><p>The reason is that a <a href="binaryhandling.html#match_context">match context</a> contains a
│ │ │  direct pointer to the binary data.</p><p>If a process simply keeps binaries (either in &quot;loop data&quot; or in the process
│ │ │  dictionary), the garbage collector can eventually shrink the binaries. If only
│ │ │  one such binary is kept, it will not be shrunk. If the process later appends to
│ │ │  a binary that has been shrunk, the binary object will be reallocated to make
│ │ │  place for the data to be appended.</p><h2 id="matching-binaries" class="section-heading">
│ │ │    <a href="#matching-binaries" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Matching Binaries</span>
│ │ │  </h2>
│ │ │ -<p>Let us revisit the example in the beginning of the previous section:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="3364762708-1">(</span><span class="p" data-group-id="3364762708-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3364762708-2">&gt;&gt;</span><span class="p" data-group-id="3364762708-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3364762708-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="3364762708-4">(</span><span class="n">T</span><span class="p" data-group-id="3364762708-4">)</span><span class="p" data-group-id="3364762708-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="3364762708-5">(</span><span class="p" data-group-id="3364762708-6">&lt;&lt;</span><span class="p" data-group-id="3364762708-6">&gt;&gt;</span><span class="p" data-group-id="3364762708-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3364762708-7">[</span><span class="p" data-group-id="3364762708-7">]</span><span class="p">.</span></code></pre><p>The first time <code class="inline">my_binary_to_list/1</code> is called, a
│ │ │ +<p>Let us revisit the example in the beginning of the previous section:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">my_binary_to_list</span><span class="p" data-group-id="0393042687-1">(</span><span class="p" data-group-id="0393042687-2">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0393042687-2">&gt;&gt;</span><span class="p" data-group-id="0393042687-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0393042687-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="0393042687-4">(</span><span class="n">T</span><span class="p" data-group-id="0393042687-4">)</span><span class="p" data-group-id="0393042687-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">my_binary_to_list</span><span class="p" data-group-id="0393042687-5">(</span><span class="p" data-group-id="0393042687-6">&lt;&lt;</span><span class="p" data-group-id="0393042687-6">&gt;&gt;</span><span class="p" data-group-id="0393042687-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0393042687-7">[</span><span class="p" data-group-id="0393042687-7">]</span><span class="p">.</span></code></pre><p>The first time <code class="inline">my_binary_to_list/1</code> is called, a
│ │ │  <a href="binaryhandling.html#match_context">match context</a> is created. The match context
│ │ │  points to the first byte of the binary. 1 byte is matched out and the match
│ │ │  context is updated to point to the second byte in the binary.</p><p>At this point it would make sense to create a
│ │ │  <a href="binaryhandling.html#sub_binary">sub binary</a>, but in this particular example the
│ │ │  compiler sees that there will soon be a call to a function (in this case, to
│ │ │  <code class="inline">my_binary_to_list/1</code> itself) that immediately will create a new match context
│ │ │  and discard the sub binary.</p><p>Therefore <code class="inline">my_binary_to_list/1</code> calls itself with the match context instead of
│ │ │  with a sub binary. The instruction that initializes the matching operation
│ │ │  basically does nothing when it sees that it was passed a match context instead
│ │ │  of a binary.</p><p>When the end of the binary is reached and the second clause matches, the match
│ │ │  context will simply be discarded (removed in the next garbage collection, as
│ │ │  there is no longer any reference to it).</p><p>To summarize, <code class="inline">my_binary_to_list/1</code> only needs to create <em>one</em> match context and
│ │ │  no sub binaries.</p><p>Notice that the match context in <code class="inline">my_binary_to_list/1</code> was discarded when the
│ │ │  entire binary had been traversed. What happens if the iteration stops before it
│ │ │ -has reached the end of the binary? Will the optimization still work?</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="5064017429-1">(</span><span class="p" data-group-id="5064017429-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5064017429-2">&gt;&gt;</span><span class="p" data-group-id="5064017429-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +has reached the end of the binary? Will the optimization still work?</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="4480947629-1">(</span><span class="p" data-group-id="4480947629-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4480947629-2">&gt;&gt;</span><span class="p" data-group-id="4480947629-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">T</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="5064017429-3">(</span><span class="p" data-group-id="5064017429-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5064017429-4">&gt;&gt;</span><span class="p" data-group-id="5064017429-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">after_zero</span><span class="p" data-group-id="5064017429-5">(</span><span class="n">T</span><span class="p" data-group-id="5064017429-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="5064017429-6">(</span><span class="p" data-group-id="5064017429-7">&lt;&lt;</span><span class="p" data-group-id="5064017429-7">&gt;&gt;</span><span class="p" data-group-id="5064017429-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5064017429-8">&lt;&lt;</span><span class="p" data-group-id="5064017429-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>Yes, it will. The compiler will remove the building of the sub binary in the
│ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="4480947629-3">(</span><span class="p" data-group-id="4480947629-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4480947629-4">&gt;&gt;</span><span class="p" data-group-id="4480947629-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">after_zero</span><span class="p" data-group-id="4480947629-5">(</span><span class="n">T</span><span class="p" data-group-id="4480947629-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="4480947629-6">(</span><span class="p" data-group-id="4480947629-7">&lt;&lt;</span><span class="p" data-group-id="4480947629-7">&gt;&gt;</span><span class="p" data-group-id="4480947629-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4480947629-8">&lt;&lt;</span><span class="p" data-group-id="4480947629-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>Yes, it will. The compiler will remove the building of the sub binary in the
│ │ │  second clause:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="0258108686-1">(</span><span class="p" data-group-id="0258108686-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0258108686-2">&gt;&gt;</span><span class="p" data-group-id="0258108686-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">after_zero</span><span class="p" data-group-id="0258108686-3">(</span><span class="n">T</span><span class="p" data-group-id="0258108686-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>But it will generate code that builds a sub binary in the first clause:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="7729891213-1">(</span><span class="p" data-group-id="7729891213-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7729891213-2">&gt;&gt;</span><span class="p" data-group-id="7729891213-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="9557435604-1">(</span><span class="p" data-group-id="9557435604-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9557435604-2">&gt;&gt;</span><span class="p" data-group-id="9557435604-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">after_zero</span><span class="p" data-group-id="9557435604-3">(</span><span class="n">T</span><span class="p" data-group-id="9557435604-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>But it will generate code that builds a sub binary in the first clause:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="0181775233-1">(</span><span class="p" data-group-id="0181775233-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0181775233-2">&gt;&gt;</span><span class="p" data-group-id="0181775233-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">T</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Therefore, <code class="inline">after_zero/1</code> builds one match context and one sub binary (assuming
│ │ │ -it is passed a binary that contains a zero byte).</p><p>Code like the following will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="4920953895-1">(</span><span class="n">Buffer</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4920953895-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4920953895-2">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="4920953895-3">(</span><span class="n">Acc</span><span class="p" data-group-id="4920953895-3">)</span><span class="p">,</span><span class="n">Buffer</span><span class="p" data-group-id="4920953895-2">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="4920953895-4">(</span><span class="p" data-group-id="4920953895-5">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4920953895-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="4920953895-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="4920953895-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="4920953895-6">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="4920953895-7">(</span><span class="p" data-group-id="4920953895-8">&lt;&lt;</span><span class="n">Byte</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4920953895-8">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="4920953895-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="4920953895-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4920953895-10">[</span><span class="n">Byte</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="4920953895-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="4920953895-9">)</span><span class="p">.</span></code></pre><p>The compiler removes building of sub binaries in the second and third clauses,
│ │ │ +it is passed a binary that contains a zero byte).</p><p>Code like the following will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="7502873241-1">(</span><span class="n">Buffer</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7502873241-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7502873241-2">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="7502873241-3">(</span><span class="n">Acc</span><span class="p" data-group-id="7502873241-3">)</span><span class="p">,</span><span class="n">Buffer</span><span class="p" data-group-id="7502873241-2">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="7502873241-4">(</span><span class="p" data-group-id="7502873241-5">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7502873241-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="7502873241-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="7502873241-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="7502873241-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="7502873241-7">(</span><span class="p" data-group-id="7502873241-8">&lt;&lt;</span><span class="n">Byte</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7502873241-8">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="p" data-group-id="7502873241-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">all_but_zeroes_to_list</span><span class="p" data-group-id="7502873241-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7502873241-10">[</span><span class="n">Byte</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="7502873241-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Remaining</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="7502873241-9">)</span><span class="p">.</span></code></pre><p>The compiler removes building of sub binaries in the second and third clauses,
│ │ │  and it adds an instruction to the first clause that converts <code class="inline">Buffer</code> from a
│ │ │  match context to a sub binary (or do nothing if <code class="inline">Buffer</code> is a binary already).</p><p>But in more complicated code, how can one know whether the optimization is
│ │ │  applied or not?</p><p><a href="" id="bin_opt_info"></a></p><h3 id="option-bin_opt_info" class="section-heading">
│ │ │    <a href="#option-bin_opt_info" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Option bin_opt_info</span>
│ │ │ @@ -354,38 +354,38 @@
│ │ │  <p>Use the <code class="inline">bin_opt_info</code> option to have the compiler print a lot of information
│ │ │  about binary optimizations. It can be given either to the compiler or <code class="inline">erlc</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">erlc</span><span class="w"> </span><span class="o">+</span><span class="ss">bin_opt_info</span><span class="w"> </span><span class="n">Mod</span><span class="p">.</span><span class="ss">erl</span></code></pre><p>or passed through an environment variable:</p><pre><code class="makeup erlang" translate="no"><span class="ss">export</span><span class="w"> </span><span class="n">ERL_COMPILER_OPTIONS</span><span class="o">=</span><span class="ss">bin_opt_info</span></code></pre><p>Notice that the <code class="inline">bin_opt_info</code> is not meant to be a permanent option added to
│ │ │  your <code class="inline">Makefile</code>s, because all messages that it generates cannot be eliminated.
│ │ │  Therefore, passing the option through the environment is in most cases the most
│ │ │  practical approach.</p><p>The warnings look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="o">/</span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">60</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">NOT</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">binary</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">returned</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">function</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="o">/</span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">62</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">context</span><span class="w"> </span><span class="ss">reused</span></code></pre><p>To make it clearer exactly what code the warnings refer to, the warnings in the
│ │ │  following examples are inserted as comments after the clause they refer to, for
│ │ │ -example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="6722476795-1">(</span><span class="p" data-group-id="6722476795-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6722476795-2">&gt;&gt;</span><span class="p" data-group-id="6722476795-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">after_zero</span><span class="p" data-group-id="9879939614-1">(</span><span class="p" data-group-id="9879939614-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9879939614-2">&gt;&gt;</span><span class="p" data-group-id="9879939614-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │           </span><span class="c1">%% BINARY CREATED: binary is returned from the function</span><span class="w">
│ │ │      </span><span class="n">T</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="6722476795-3">(</span><span class="p" data-group-id="6722476795-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6722476795-4">&gt;&gt;</span><span class="p" data-group-id="6722476795-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="9879939614-3">(</span><span class="p" data-group-id="9879939614-4">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9879939614-4">&gt;&gt;</span><span class="p" data-group-id="9879939614-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │           </span><span class="c1">%% OPTIMIZED: match context reused</span><span class="w">
│ │ │ -    </span><span class="nf">after_zero</span><span class="p" data-group-id="6722476795-5">(</span><span class="n">T</span><span class="p" data-group-id="6722476795-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">after_zero</span><span class="p" data-group-id="6722476795-6">(</span><span class="p" data-group-id="6722476795-7">&lt;&lt;</span><span class="p" data-group-id="6722476795-7">&gt;&gt;</span><span class="p" data-group-id="6722476795-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6722476795-8">&lt;&lt;</span><span class="p" data-group-id="6722476795-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>The warning for the first clause says that the creation of a sub binary cannot
│ │ │ +    </span><span class="nf">after_zero</span><span class="p" data-group-id="9879939614-5">(</span><span class="n">T</span><span class="p" data-group-id="9879939614-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">after_zero</span><span class="p" data-group-id="9879939614-6">(</span><span class="p" data-group-id="9879939614-7">&lt;&lt;</span><span class="p" data-group-id="9879939614-7">&gt;&gt;</span><span class="p" data-group-id="9879939614-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9879939614-8">&lt;&lt;</span><span class="p" data-group-id="9879939614-8">&gt;&gt;</span><span class="p">.</span></code></pre><p>The warning for the first clause says that the creation of a sub binary cannot
│ │ │  be delayed, because it will be returned. The warning for the second clause says
│ │ │  that a sub binary will not be created (yet).</p><h3 id="unused-variables" class="section-heading">
│ │ │    <a href="#unused-variables" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Unused Variables</span>
│ │ │  </h3>
│ │ │  <p>The compiler figures out if a variable is unused. The same code is generated for
│ │ │ -each of the following functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">count1</span><span class="p" data-group-id="7998787685-1">(</span><span class="p" data-group-id="7998787685-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7998787685-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="7998787685-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count1</span><span class="p" data-group-id="7998787685-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="7998787685-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">count1</span><span class="p" data-group-id="7998787685-4">(</span><span class="p" data-group-id="7998787685-5">&lt;&lt;</span><span class="p" data-group-id="7998787685-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="7998787685-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │ +each of the following functions:</p><pre><code class="makeup erlang" translate="no"><span class="nf">count1</span><span class="p" data-group-id="2030607815-1">(</span><span class="p" data-group-id="2030607815-2">&lt;&lt;</span><span class="p">_</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2030607815-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="2030607815-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count1</span><span class="p" data-group-id="2030607815-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="2030607815-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">count1</span><span class="p" data-group-id="2030607815-4">(</span><span class="p" data-group-id="2030607815-5">&lt;&lt;</span><span class="p" data-group-id="2030607815-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="2030607815-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">count2</span><span class="p" data-group-id="7998787685-6">(</span><span class="p" data-group-id="7998787685-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7998787685-7">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="7998787685-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count2</span><span class="p" data-group-id="7998787685-8">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="7998787685-8">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">count2</span><span class="p" data-group-id="7998787685-9">(</span><span class="p" data-group-id="7998787685-10">&lt;&lt;</span><span class="p" data-group-id="7998787685-10">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="7998787685-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">count2</span><span class="p" data-group-id="2030607815-6">(</span><span class="p" data-group-id="2030607815-7">&lt;&lt;</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2030607815-7">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="2030607815-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count2</span><span class="p" data-group-id="2030607815-8">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="2030607815-8">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">count2</span><span class="p" data-group-id="2030607815-9">(</span><span class="p" data-group-id="2030607815-10">&lt;&lt;</span><span class="p" data-group-id="2030607815-10">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="2030607815-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">count3</span><span class="p" data-group-id="7998787685-11">(</span><span class="p" data-group-id="7998787685-12">&lt;&lt;</span><span class="p">_</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7998787685-12">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="7998787685-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count3</span><span class="p" data-group-id="7998787685-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="7998787685-13">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">count3</span><span class="p" data-group-id="7998787685-14">(</span><span class="p" data-group-id="7998787685-15">&lt;&lt;</span><span class="p" data-group-id="7998787685-15">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="7998787685-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span></code></pre><p>In each iteration, the first 8 bits in the binary will be skipped, not matched
│ │ │ +</span><span class="nf">count3</span><span class="p" data-group-id="2030607815-11">(</span><span class="p" data-group-id="2030607815-12">&lt;&lt;</span><span class="p">_</span><span class="n">H</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2030607815-12">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="2030607815-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">count3</span><span class="p" data-group-id="2030607815-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="2030607815-13">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">count3</span><span class="p" data-group-id="2030607815-14">(</span><span class="p" data-group-id="2030607815-15">&lt;&lt;</span><span class="p" data-group-id="2030607815-15">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="n">Count</span><span class="p" data-group-id="2030607815-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Count</span><span class="p">.</span></code></pre><p>In each iteration, the first 8 bits in the binary will be skipped, not matched
│ │ │  out.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="commoncaveats.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/bit_syntax.html
│ │ │ @@ -119,48 +119,48 @@
│ │ │    <a href="#introduction" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Introduction</span>
│ │ │  </h2>
│ │ │  <p>The complete specification for the bit syntax appears in the
│ │ │  <a href="../../doc/system/expressions.html#bit-syntax-expressions">Reference Manual</a>.</p><p>In Erlang, a Bin is used for constructing binaries and matching binary patterns.
│ │ │ -A Bin is written with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4984700037-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="4984700037-1">&gt;&gt;</span></code></pre><p>A Bin is a low-level sequence of bits or bytes. The purpose of a Bin is to
│ │ │ -enable construction of binaries:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6297344941-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="6297344941-1">&gt;&gt;</span></code></pre><p>All elements must be bound. Or match a binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0100315987-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="0100315987-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span></code></pre><p>Here, <code class="inline">Bin</code> is bound and the elements are bound or unbound, as in any match.</p><p>A Bin does not need to consist of a whole number of bytes.</p><p>A <em>bitstring</em> is a sequence of zero or more bits, where the number of bits does
│ │ │ +A Bin is written with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9510783111-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="9510783111-1">&gt;&gt;</span></code></pre><p>A Bin is a low-level sequence of bits or bytes. The purpose of a Bin is to
│ │ │ +enable construction of binaries:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5062217222-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="5062217222-1">&gt;&gt;</span></code></pre><p>All elements must be bound. Or match a binary:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0564232585-1">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">En</span><span class="p" data-group-id="0564232585-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span></code></pre><p>Here, <code class="inline">Bin</code> is bound and the elements are bound or unbound, as in any match.</p><p>A Bin does not need to consist of a whole number of bytes.</p><p>A <em>bitstring</em> is a sequence of zero or more bits, where the number of bits does
│ │ │  not need to be divisible by 8. If the number of bits is divisible by 8, the
│ │ │  bitstring is also a binary.</p><p>Each element specifies a certain <em>segment</em> of the bitstring. A segment is a set
│ │ │  of contiguous bits of the binary (not necessarily on a byte boundary). The first
│ │ │  element specifies the initial segment, the second element specifies the
│ │ │  following segment, and so on.</p><p>The following examples illustrate how binaries are constructed, or matched, and
│ │ │  how elements and tails are specified.</p><h3 id="examples" class="section-heading">
│ │ │    <a href="#examples" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Examples</span>
│ │ │  </h3>
│ │ │  <p><em>Example 1:</em> A binary can be constructed from a set of constants or a string
│ │ │ -literal:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin11</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3493965436-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">17</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="3493965436-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Bin12</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3493965436-2">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3493965436-2">&gt;&gt;</span></code></pre><p>This gives two binaries of size 3, with the following evaluations:</p><ul><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin11)</code></a> evaluates to <code class="inline">[1, 17, 42]</code>.</li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin12)</code></a> evaluates to <code class="inline">[97, 98, 99]</code>.</li></ul><p><em>Example 2:</em>Similarly, a binary can be constructed from a set of bound
│ │ │ +literal:</p><pre><code class="makeup erlang" translate="no"><span class="n">Bin11</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6759760782-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">17</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="6759760782-1">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Bin12</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6759760782-2">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="6759760782-2">&gt;&gt;</span></code></pre><p>This gives two binaries of size 3, with the following evaluations:</p><ul><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin11)</code></a> evaluates to <code class="inline">[1, 17, 42]</code>.</li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin12)</code></a> evaluates to <code class="inline">[97, 98, 99]</code>.</li></ul><p><em>Example 2:</em>Similarly, a binary can be constructed from a set of bound
│ │ │  variables:</p><pre><code class="makeup erlang" translate="no"><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">17</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2033763548-1">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="2033763548-1">&gt;&gt;</span></code></pre><p>This gives a binary of size 4. Here, a <em>size expression</em> is used for the
│ │ │ +</span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7599866475-1">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="7599866475-1">&gt;&gt;</span></code></pre><p>This gives a binary of size 4. Here, a <em>size expression</em> is used for the
│ │ │  variable <code class="inline">C</code> to specify a 16-bits segment of <code class="inline">Bin2</code>.</p><p><a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_list/1"><code class="inline">binary_to_list(Bin2)</code></a> evaluates to <code class="inline">[1, 17, 00, 42]</code>.</p><p><em>Example 3:</em> A Bin can also be used for matching. <code class="inline">D</code>, <code class="inline">E</code>, and <code class="inline">F</code> are unbound
│ │ │ -variables, and <code class="inline">Bin2</code> is bound, as in Example 2:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2070690593-1">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="2070690593-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin2</span></code></pre><p>This gives <code class="inline">D = 273</code>, <code class="inline">E = 00</code>, and F binds to a binary of size 1:
│ │ │ +variables, and <code class="inline">Bin2</code> is bound, as in Example 2:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8660346862-1">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="8660346862-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin2</span></code></pre><p>This gives <code class="inline">D = 273</code>, <code class="inline">E = 00</code>, and F binds to a binary of size 1:
│ │ │  <code class="inline">binary_to_list(F) = [42]</code>.</p><p><em>Example 4:</em> The following is a more elaborate example of matching. Here,
│ │ │  <code class="inline">Dgram</code> is bound to the consecutive bytes of an IP datagram of IP protocol
│ │ │ -version 4. The ambition is to extract the header and the data of the datagram:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0806131522-1">(</span><span class="n">IP_VERSION</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="0806131522-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0806131522-2">(</span><span class="n">IP_MIN_HDR_LEN</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="0806131522-2">)</span><span class="p">.</span><span class="w">
│ │ │ +version 4. The ambition is to extract the header and the data of the datagram:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9199717457-1">(</span><span class="n">IP_VERSION</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="9199717457-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9199717457-2">(</span><span class="n">IP_MIN_HDR_LEN</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="9199717457-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">DgramSize</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="0806131522-3">(</span><span class="n">Dgram</span><span class="p" data-group-id="0806131522-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">DgramSize</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="9199717457-3">(</span><span class="n">Dgram</span><span class="p" data-group-id="9199717457-3">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="k">case</span><span class="w"> </span><span class="n">Dgram</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0806131522-4">&lt;&lt;</span><span class="o">?</span><span class="n">IP_VERSION</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">HLen</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">SrvcType</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">TotLen</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9199717457-4">&lt;&lt;</span><span class="o">?</span><span class="n">IP_VERSION</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">HLen</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="n">SrvcType</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">TotLen</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w">
│ │ │        </span><span class="n">ID</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w"> </span><span class="n">Flgs</span><span class="p">:</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">FragOff</span><span class="p">:</span><span class="mi">13</span><span class="p">,</span><span class="w">
│ │ │        </span><span class="n">TTL</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">Proto</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="n">HdrChkSum</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="w">
│ │ │        </span><span class="n">SrcIP</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="w">
│ │ │ -      </span><span class="n">DestIP</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="w"> </span><span class="n">RestDgram</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0806131522-4">&gt;&gt;</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">HLen</span><span class="o">&gt;=</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="n">HLen</span><span class="o">=&lt;</span><span class="n">DgramSize</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="n">OptsLen</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="p" data-group-id="0806131522-5">(</span><span class="n">HLen</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">?</span><span class="n">IP_MIN_HDR_LEN</span><span class="p" data-group-id="0806131522-5">)</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0806131522-6">&lt;&lt;</span><span class="n">Opts</span><span class="p">:</span><span class="n">OptsLen</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Data</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0806131522-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RestDgram</span><span class="p">,</span><span class="w">
│ │ │ +      </span><span class="n">DestIP</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="w"> </span><span class="n">RestDgram</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9199717457-4">&gt;&gt;</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">HLen</span><span class="o">&gt;=</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="n">HLen</span><span class="o">=&lt;</span><span class="n">DgramSize</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="n">OptsLen</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">4</span><span class="o">*</span><span class="p" data-group-id="9199717457-5">(</span><span class="n">HLen</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">?</span><span class="n">IP_MIN_HDR_LEN</span><span class="p" data-group-id="9199717457-5">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9199717457-6">&lt;&lt;</span><span class="n">Opts</span><span class="p">:</span><span class="n">OptsLen</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Data</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9199717457-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RestDgram</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>Here, the segment corresponding to the <code class="inline">Opts</code> variable has a <em>type modifier</em>,
│ │ │  specifying that <code class="inline">Opts</code> is to bind to a binary. All other variables have the
│ │ │  default type equal to unsigned integer.</p><p>An IP datagram header is of variable length. This length is measured in the
│ │ │  number of 32-bit words and is given in the segment corresponding to <code class="inline">HLen</code>. The
│ │ │  minimum value of <code class="inline">HLen</code> is 5. It is the segment corresponding to <code class="inline">Opts</code> that is
│ │ │  variable, so if <code class="inline">HLen</code> is equal to 5, <code class="inline">Opts</code> becomes an empty binary.</p><p>The tail variables <code class="inline">RestDgram</code> and <code class="inline">Data</code> bind to binaries, as all tail
│ │ │ @@ -218,80 +218,80 @@
│ │ │  <p>This section describes the rules for constructing binaries using the bit syntax.
│ │ │  Unlike when constructing lists or tuples, the construction of a binary can fail
│ │ │  with a <code class="inline">badarg</code> exception.</p><p>There can be zero or more segments in a binary to be constructed. The expression
│ │ │  <code class="inline">&lt;&lt;&gt;&gt;</code> constructs a zero length binary.</p><p>Each segment in a binary can consist of zero or more bits. There are no
│ │ │  alignment rules for individual segments of type <code class="inline">integer</code> and <code class="inline">float</code>. For
│ │ │  binaries and bitstrings without size, the unit specifies the alignment. Since
│ │ │  the default alignment for the <code class="inline">binary</code> type is 8, the size of a binary segment
│ │ │ -must be a multiple of 8 bits, that is, only whole bytes.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3906627028-1">&lt;&lt;</span><span class="n">Bin</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Bitstring</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3906627028-1">&gt;&gt;</span></code></pre><p>The variable <code class="inline">Bin</code> must contain a whole number of bytes, because the <code class="inline">binary</code>
│ │ │ +must be a multiple of 8 bits, that is, only whole bytes.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3669284977-1">&lt;&lt;</span><span class="n">Bin</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Bitstring</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3669284977-1">&gt;&gt;</span></code></pre><p>The variable <code class="inline">Bin</code> must contain a whole number of bytes, because the <code class="inline">binary</code>
│ │ │  type defaults to <code class="inline">unit:8</code>. A <code class="inline">badarg</code> exception is generated if <code class="inline">Bin</code> consist
│ │ │  of, for example, 17 bits.</p><p>The <code class="inline">Bitstring</code> variable can consist of any number of bits, for example, 0, 1,
│ │ │  8, 11, 17, 42, and so on. This is because the default <code class="inline">unit</code> for bitstrings
│ │ │  is 1.</p><p>For clarity, it is recommended not to change the unit size for binaries.
│ │ │  Instead, use <code class="inline">binary</code> when you need byte alignment and <code class="inline">bitstring</code> when you need
│ │ │  bit alignment.</p><p>The following example successfully constructs a bitstring of 7 bits, provided
│ │ │ -that all of X and Y are integers:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2880117863-1">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">6</span><span class="p" data-group-id="2880117863-1">&gt;&gt;</span></code></pre><p>As mentioned earlier, segments have the following general syntax:</p><p><code class="inline">Value:Size/TypeSpecifierList</code></p><p>When constructing binaries, <code class="inline">Value</code> and <code class="inline">Size</code> can be any Erlang expression.
│ │ │ +that all of X and Y are integers:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6642997616-1">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">6</span><span class="p" data-group-id="6642997616-1">&gt;&gt;</span></code></pre><p>As mentioned earlier, segments have the following general syntax:</p><p><code class="inline">Value:Size/TypeSpecifierList</code></p><p>When constructing binaries, <code class="inline">Value</code> and <code class="inline">Size</code> can be any Erlang expression.
│ │ │  However, for syntactical reasons, both <code class="inline">Value</code> and <code class="inline">Size</code> must be enclosed in
│ │ │  parenthesis if the expression consists of anything more than a single literal or
│ │ │ -a variable. The following gives a compiler syntax error:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6877509498-1">&lt;&lt;</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="6877509498-1">&gt;&gt;</span></code></pre><p>This expression must be rewritten into the following, to be accepted by the
│ │ │ -compiler:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0373061358-1">&lt;&lt;</span><span class="p" data-group-id="0373061358-2">(</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="0373061358-2">)</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0373061358-1">&gt;&gt;</span></code></pre><h3 id="including-literal-strings" class="section-heading">
│ │ │ +a variable. The following gives a compiler syntax error:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4750180555-1">&lt;&lt;</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="4750180555-1">&gt;&gt;</span></code></pre><p>This expression must be rewritten into the following, to be accepted by the
│ │ │ +compiler:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0065772382-1">&lt;&lt;</span><span class="p" data-group-id="0065772382-2">(</span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="0065772382-2">)</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0065772382-1">&gt;&gt;</span></code></pre><h3 id="including-literal-strings" class="section-heading">
│ │ │    <a href="#including-literal-strings" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Including Literal Strings</span>
│ │ │  </h3>
│ │ │ -<p>A literal string can be written instead of an element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5747223942-1">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="5747223942-1">&gt;&gt;</span></code></pre><p>This is syntactic sugar for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3315325746-1">&lt;&lt;</span><span class="sc">$h</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$o</span><span class="p" data-group-id="3315325746-1">&gt;&gt;</span></code></pre><h2 id="matching-binaries" class="section-heading">
│ │ │ +<p>A literal string can be written instead of an element:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4851027357-1">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="4851027357-1">&gt;&gt;</span></code></pre><p>This is syntactic sugar for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5801920070-1">&lt;&lt;</span><span class="sc">$h</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$l</span><span class="p">,</span><span class="sc">$o</span><span class="p" data-group-id="5801920070-1">&gt;&gt;</span></code></pre><h2 id="matching-binaries" class="section-heading">
│ │ │    <a href="#matching-binaries" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Matching Binaries</span>
│ │ │  </h2>
│ │ │  <p>This section describes the rules for matching binaries, using the bit syntax.</p><p>There can be zero or more segments in a binary pattern. A binary pattern can
│ │ │  occur wherever patterns are allowed, including inside other patterns. Binary
│ │ │  patterns cannot be nested. The pattern <code class="inline">&lt;&lt;&gt;&gt;</code> matches a zero length binary.</p><p>Each segment in a binary can consist of zero or more bits. A segment of type
│ │ │  <code class="inline">binary</code> must have a size evenly divisible by 8 (or divisible by the unit size,
│ │ │  if the unit size has been changed). A segment of type <code class="inline">bitstring</code> has no
│ │ │  restrictions on the size. A segment of type <code class="inline">float</code> must have size 64 or 32.</p><p>As mentioned earlier, segments have the following general syntax:</p><p><code class="inline">Value:Size/TypeSpecifierList</code></p><p>When matching <code class="inline">Value</code>, value must be either a variable or an integer, or a
│ │ │  floating point literal. Expressions are not allowed.</p><p><code class="inline">Size</code> must be a
│ │ │  <a href="../../doc/system/expressions.html#guard-expressions">guard expression</a>, which can use
│ │ │ -literals and previously bound variables. The following is not allowed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="4546923452-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4546923452-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4546923452-2">&gt;&gt;</span><span class="p" data-group-id="4546923452-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="4546923452-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="4546923452-3">}</span><span class="p">.</span></code></pre><p>The two occurrences of <code class="inline">N</code> are not related. The compiler will complain that the
│ │ │ -<code class="inline">N</code> in the size field is unbound.</p><p>The correct way to write this example is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="8691048627-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="8691048627-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="8691048627-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="8691048627-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="8691048627-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="8691048627-3">}</span><span class="p">.</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Before OTP 23, <code class="inline">Size</code> was restricted to be an integer or a variable bound to
│ │ │ +literals and previously bound variables. The following is not allowed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="9243155581-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9243155581-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9243155581-2">&gt;&gt;</span><span class="p" data-group-id="9243155581-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="9243155581-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="9243155581-3">}</span><span class="p">.</span></code></pre><p>The two occurrences of <code class="inline">N</code> are not related. The compiler will complain that the
│ │ │ +<code class="inline">N</code> in the size field is unbound.</p><p>The correct way to write this example is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="4662466262-1">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="4662466262-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="4662466262-2">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">N</span><span class="p">,</span><span class="n">T</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4662466262-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Bin</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="4662466262-3">{</span><span class="n">X</span><span class="p">,</span><span class="n">T</span><span class="p" data-group-id="4662466262-3">}</span><span class="p">.</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Before OTP 23, <code class="inline">Size</code> was restricted to be an integer or a variable bound to
│ │ │  an integer.</p></section><h3 id="binding-and-using-a-size-variable" class="section-heading">
│ │ │    <a href="#binding-and-using-a-size-variable" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Binding and Using a Size Variable</span>
│ │ │  </h3>
│ │ │  <p>There is one exception to the rule that a variable that is used as size must be
│ │ │  previously bound. It is possible to match and bind a variable, and use it as a
│ │ │ -size within the same binary pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="9055358689-1">(</span><span class="p" data-group-id="9055358689-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="n">Sz</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9055358689-2">&gt;&gt;</span><span class="p" data-group-id="9055358689-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="9055358689-3">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="9055358689-3">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is bound to the value in the first byte of the binary. <code class="inline">Sz</code> is then
│ │ │ -used at the number of bytes to match out as a binary.</p><p>Starting in OTP 23, the size can be a guard expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="5603894736-1">(</span><span class="p" data-group-id="5603894736-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="p" data-group-id="5603894736-3">(</span><span class="p" data-group-id="5603894736-4">(</span><span class="n">Sz</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="5603894736-4">)</span><span class="o">*</span><span class="mi">8</span><span class="p" data-group-id="5603894736-3">)</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5603894736-2">&gt;&gt;</span><span class="p" data-group-id="5603894736-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="5603894736-5">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="5603894736-5">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is the combined size of the header and the payload, so we will need to
│ │ │ +size within the same binary pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="7512122105-1">(</span><span class="p" data-group-id="7512122105-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="n">Sz</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7512122105-2">&gt;&gt;</span><span class="p" data-group-id="7512122105-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="7512122105-3">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="7512122105-3">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is bound to the value in the first byte of the binary. <code class="inline">Sz</code> is then
│ │ │ +used at the number of bytes to match out as a binary.</p><p>Starting in OTP 23, the size can be a guard expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="5868589254-1">(</span><span class="p" data-group-id="5868589254-2">&lt;&lt;</span><span class="n">Sz</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Payload</span><span class="p">:</span><span class="p" data-group-id="5868589254-3">(</span><span class="p" data-group-id="5868589254-4">(</span><span class="n">Sz</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="5868589254-4">)</span><span class="o">*</span><span class="mi">8</span><span class="p" data-group-id="5868589254-3">)</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5868589254-2">&gt;&gt;</span><span class="p" data-group-id="5868589254-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="5868589254-5">{</span><span class="n">Payload</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="5868589254-5">}</span><span class="p">.</span></code></pre><p>Here <code class="inline">Sz</code> is the combined size of the header and the payload, so we will need to
│ │ │  subtract one byte to get the size of the payload.</p><h3 id="getting-the-rest-of-the-binary-or-bitstring" class="section-heading">
│ │ │    <a href="#getting-the-rest-of-the-binary-or-bitstring" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Getting the Rest of the Binary or Bitstring</span>
│ │ │  </h3>
│ │ │ -<p>To match out the rest of a binary, specify a binary field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="8856206649-1">(</span><span class="p" data-group-id="8856206649-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="8856206649-2">&gt;&gt;</span><span class="p" data-group-id="8856206649-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>The size of the tail must be evenly divisible by 8.</p><p>To match out the rest of a bitstring, specify a field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="0483602125-1">(</span><span class="p" data-group-id="0483602125-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="0483602125-2">&gt;&gt;</span><span class="p" data-group-id="0483602125-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>There are no restrictions on the number of bits in the tail.</p><h2 id="appending-to-a-binary" class="section-heading">
│ │ │ +<p>To match out the rest of a binary, specify a binary field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="0570771327-1">(</span><span class="p" data-group-id="0570771327-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="0570771327-2">&gt;&gt;</span><span class="p" data-group-id="0570771327-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>The size of the tail must be evenly divisible by 8.</p><p>To match out the rest of a bitstring, specify a field without size:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="1316307180-1">(</span><span class="p" data-group-id="1316307180-2">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">Rest</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="1316307180-2">&gt;&gt;</span><span class="p" data-group-id="1316307180-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>There are no restrictions on the number of bits in the tail.</p><h2 id="appending-to-a-binary" class="section-heading">
│ │ │    <a href="#appending-to-a-binary" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Appending to a Binary</span>
│ │ │  </h2>
│ │ │ -<p>Appending to a binary in an efficient way can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">triples_to_bin</span><span class="p" data-group-id="3186207497-1">(</span><span class="n">T</span><span class="p" data-group-id="3186207497-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="3186207497-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3186207497-3">&lt;&lt;</span><span class="p" data-group-id="3186207497-3">&gt;&gt;</span><span class="p" data-group-id="3186207497-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Appending to a binary in an efficient way can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">triples_to_bin</span><span class="p" data-group-id="0932614138-1">(</span><span class="n">T</span><span class="p" data-group-id="0932614138-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="0932614138-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0932614138-3">&lt;&lt;</span><span class="p" data-group-id="0932614138-3">&gt;&gt;</span><span class="p" data-group-id="0932614138-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="3186207497-4">(</span><span class="p" data-group-id="3186207497-5">[</span><span class="p" data-group-id="3186207497-6">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p" data-group-id="3186207497-6">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="3186207497-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3186207497-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="3186207497-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3186207497-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">X</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Z</span><span class="p">:</span><span class="mi">32</span><span class="p" data-group-id="3186207497-8">&gt;&gt;</span><span class="p" data-group-id="3186207497-7">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="3186207497-9">(</span><span class="p" data-group-id="3186207497-10">[</span><span class="p" data-group-id="3186207497-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3186207497-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="0932614138-4">(</span><span class="p" data-group-id="0932614138-5">[</span><span class="p" data-group-id="0932614138-6">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="n">Z</span><span class="p" data-group-id="0932614138-6">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="0932614138-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="0932614138-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">triples_to_bin</span><span class="p" data-group-id="0932614138-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0932614138-8">&lt;&lt;</span><span class="n">Acc</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="n">X</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Y</span><span class="p">:</span><span class="mi">32</span><span class="p">,</span><span class="n">Z</span><span class="p">:</span><span class="mi">32</span><span class="p" data-group-id="0932614138-8">&gt;&gt;</span><span class="p" data-group-id="0932614138-7">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">triples_to_bin</span><span class="p" data-group-id="0932614138-9">(</span><span class="p" data-group-id="0932614138-10">[</span><span class="p" data-group-id="0932614138-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="0932614138-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="list_comprehensions.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/c_port.html
│ │ │ @@ -148,101 +148,101 @@
│ │ │  external program, if it is written properly).</p><p>The port is created using the BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#open_port/2"><code class="inline">open_port/2</code></a> with
│ │ │  <code class="inline">{spawn,ExtPrg}</code> as the first argument. The string <code class="inline">ExtPrg</code> is the name of the
│ │ │  external program, including any command line arguments. The second argument is a
│ │ │  list of options, in this case only <code class="inline">{packet,2}</code>. This option says that a 2 byte
│ │ │  length indicator is to be used to simplify the communication between C and
│ │ │  Erlang. The Erlang port automatically adds the length indicator, but this must
│ │ │  be done explicitly in the external C program.</p><p>The process is also set to trap exits, which enables detection of failure of the
│ │ │ -external program:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3385981396-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="3385981396-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3385981396-2">(</span><span class="p" data-group-id="3385981396-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3385981396-3">]</span><span class="p" data-group-id="3385981396-2">)</span><span class="p">.</span><span class="w">
│ │ │ +external program:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5199951895-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="5199951895-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5199951895-2">(</span><span class="p" data-group-id="5199951895-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5199951895-3">]</span><span class="p" data-group-id="5199951895-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="3385981396-4">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="3385981396-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="nf">spawn</span><span class="p" data-group-id="3385981396-5">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3385981396-6">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="3385981396-6">]</span><span class="p" data-group-id="3385981396-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="5199951895-4">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="5199951895-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="nf">spawn</span><span class="p" data-group-id="5199951895-5">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5199951895-6">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="5199951895-6">]</span><span class="p" data-group-id="5199951895-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3385981396-7">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="3385981396-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="nf">register</span><span class="p" data-group-id="3385981396-8">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3385981396-9">(</span><span class="p" data-group-id="3385981396-9">)</span><span class="p" data-group-id="3385981396-8">)</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="nf">process_flag</span><span class="p" data-group-id="3385981396-10">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3385981396-10">)</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="3385981396-11">(</span><span class="p" data-group-id="3385981396-12">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="3385981396-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3385981396-13">[</span><span class="p" data-group-id="3385981396-14">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3385981396-14">}</span><span class="p" data-group-id="3385981396-13">]</span><span class="p" data-group-id="3385981396-11">)</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="nf">loop</span><span class="p" data-group-id="3385981396-15">(</span><span class="n">Port</span><span class="p" data-group-id="3385981396-15">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex1:foo/1</code> and <code class="inline">complex1:bar/1</code> can be implemented. Both send a
│ │ │ -message to the <code class="inline">complex</code> process and receive the following replies:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="5555087966-1">(</span><span class="n">X</span><span class="p" data-group-id="5555087966-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="nf">call_port</span><span class="p" data-group-id="5555087966-2">(</span><span class="p" data-group-id="5555087966-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="5555087966-3">}</span><span class="p" data-group-id="5555087966-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="5555087966-4">(</span><span class="n">Y</span><span class="p" data-group-id="5555087966-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="nf">call_port</span><span class="p" data-group-id="5555087966-5">(</span><span class="p" data-group-id="5555087966-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5555087966-6">}</span><span class="p" data-group-id="5555087966-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="5199951895-7">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="5199951895-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="nf">register</span><span class="p" data-group-id="5199951895-8">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5199951895-9">(</span><span class="p" data-group-id="5199951895-9">)</span><span class="p" data-group-id="5199951895-8">)</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="nf">process_flag</span><span class="p" data-group-id="5199951895-10">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5199951895-10">)</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="5199951895-11">(</span><span class="p" data-group-id="5199951895-12">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="5199951895-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5199951895-13">[</span><span class="p" data-group-id="5199951895-14">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="5199951895-14">}</span><span class="p" data-group-id="5199951895-13">]</span><span class="p" data-group-id="5199951895-11">)</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="nf">loop</span><span class="p" data-group-id="5199951895-15">(</span><span class="n">Port</span><span class="p" data-group-id="5199951895-15">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex1:foo/1</code> and <code class="inline">complex1:bar/1</code> can be implemented. Both send a
│ │ │ +message to the <code class="inline">complex</code> process and receive the following replies:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="7483454897-1">(</span><span class="n">X</span><span class="p" data-group-id="7483454897-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="nf">call_port</span><span class="p" data-group-id="7483454897-2">(</span><span class="p" data-group-id="7483454897-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7483454897-3">}</span><span class="p" data-group-id="7483454897-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="7483454897-4">(</span><span class="n">Y</span><span class="p" data-group-id="7483454897-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="nf">call_port</span><span class="p" data-group-id="7483454897-5">(</span><span class="p" data-group-id="7483454897-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7483454897-6">}</span><span class="p" data-group-id="7483454897-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="5555087966-7">(</span><span class="n">Msg</span><span class="p" data-group-id="5555087966-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5555087966-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5555087966-9">(</span><span class="p" data-group-id="5555087966-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5555087966-8">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="7483454897-7">(</span><span class="n">Msg</span><span class="p" data-group-id="7483454897-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7483454897-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7483454897-9">(</span><span class="p" data-group-id="7483454897-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7483454897-8">}</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5555087966-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="5555087966-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7483454897-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7483454897-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │        </span><span class="n">Result</span><span class="w">
│ │ │ -  </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process does the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="7400576532-1">(</span><span class="n">Port</span><span class="p" data-group-id="7400576532-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process does the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="5226745364-1">(</span><span class="n">Port</span><span class="p" data-group-id="5226745364-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │    </span><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7400576532-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7400576532-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -      </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7400576532-3">{</span><span class="nf">self</span><span class="p" data-group-id="7400576532-4">(</span><span class="p" data-group-id="7400576532-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7400576532-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="7400576532-6">(</span><span class="n">Msg</span><span class="p" data-group-id="7400576532-6">)</span><span class="p" data-group-id="7400576532-5">}</span><span class="p" data-group-id="7400576532-3">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5226745364-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="5226745364-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +      </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5226745364-3">{</span><span class="nf">self</span><span class="p" data-group-id="5226745364-4">(</span><span class="p" data-group-id="5226745364-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5226745364-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="5226745364-6">(</span><span class="n">Msg</span><span class="p" data-group-id="5226745364-6">)</span><span class="p" data-group-id="5226745364-5">}</span><span class="p" data-group-id="5226745364-3">}</span><span class="p">,</span><span class="w">
│ │ │        </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7400576532-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7400576532-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7400576532-8">}</span><span class="p" data-group-id="7400576532-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -          </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7400576532-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="7400576532-10">(</span><span class="n">Data</span><span class="p" data-group-id="7400576532-10">)</span><span class="p" data-group-id="7400576532-9">}</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="5226745364-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5226745364-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5226745364-8">}</span><span class="p" data-group-id="5226745364-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +          </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5226745364-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="5226745364-10">(</span><span class="n">Data</span><span class="p" data-group-id="5226745364-10">)</span><span class="p" data-group-id="5226745364-9">}</span><span class="w">
│ │ │        </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -      </span><span class="nf">loop</span><span class="p" data-group-id="7400576532-11">(</span><span class="n">Port</span><span class="p" data-group-id="7400576532-11">)</span><span class="w">
│ │ │ +      </span><span class="nf">loop</span><span class="p" data-group-id="5226745364-11">(</span><span class="n">Port</span><span class="p" data-group-id="5226745364-11">)</span><span class="w">
│ │ │    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Assuming that both the arguments and the results from the C functions are less
│ │ │  than 256, a simple encoding/decoding scheme is employed. In this scheme, <code class="inline">foo</code>
│ │ │  is represented by byte 1, <code class="inline">bar</code> is represented by 2, and the argument/result is
│ │ │ -represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="0455947072-1">(</span><span class="p" data-group-id="0455947072-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="0455947072-2">}</span><span class="p" data-group-id="0455947072-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0455947072-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="0455947072-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="0455947072-4">(</span><span class="p" data-group-id="0455947072-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0455947072-5">}</span><span class="p" data-group-id="0455947072-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0455947072-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0455947072-6">]</span><span class="p">.</span><span class="w">
│ │ │ +represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="4907960584-1">(</span><span class="p" data-group-id="4907960584-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4907960584-2">}</span><span class="p" data-group-id="4907960584-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4907960584-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4907960584-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="4907960584-4">(</span><span class="p" data-group-id="4907960584-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4907960584-5">}</span><span class="p" data-group-id="4907960584-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4907960584-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4907960584-6">]</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="0455947072-7">(</span><span class="p" data-group-id="0455947072-8">[</span><span class="n">Int</span><span class="p" data-group-id="0455947072-8">]</span><span class="p" data-group-id="0455947072-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functionality for stopping the port and
│ │ │ -detecting port failures, is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3412050213-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="3412050213-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3412050213-2">(</span><span class="p" data-group-id="3412050213-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3412050213-3">]</span><span class="p" data-group-id="3412050213-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3412050213-4">(</span><span class="p" data-group-id="3412050213-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3412050213-5">]</span><span class="p" data-group-id="3412050213-4">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="3412050213-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="3412050213-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="3412050213-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3412050213-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="3412050213-8">]</span><span class="p" data-group-id="3412050213-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="3412050213-9">(</span><span class="p" data-group-id="3412050213-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="4907960584-7">(</span><span class="p" data-group-id="4907960584-8">[</span><span class="n">Int</span><span class="p" data-group-id="4907960584-8">]</span><span class="p" data-group-id="4907960584-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functionality for stopping the port and
│ │ │ +detecting port failures, is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4694032052-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="4694032052-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4694032052-2">(</span><span class="p" data-group-id="4694032052-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4694032052-3">]</span><span class="p" data-group-id="4694032052-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4694032052-4">(</span><span class="p" data-group-id="4694032052-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4694032052-5">]</span><span class="p" data-group-id="4694032052-4">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="4694032052-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="4694032052-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="4694032052-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4694032052-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="4694032052-8">]</span><span class="p" data-group-id="4694032052-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="4694032052-9">(</span><span class="p" data-group-id="4694032052-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="3412050213-10">(</span><span class="n">X</span><span class="p" data-group-id="3412050213-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="3412050213-11">(</span><span class="p" data-group-id="3412050213-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3412050213-12">}</span><span class="p" data-group-id="3412050213-11">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="3412050213-13">(</span><span class="n">Y</span><span class="p" data-group-id="3412050213-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="3412050213-14">(</span><span class="p" data-group-id="3412050213-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3412050213-15">}</span><span class="p" data-group-id="3412050213-14">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="4694032052-10">(</span><span class="n">X</span><span class="p" data-group-id="4694032052-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="4694032052-11">(</span><span class="p" data-group-id="4694032052-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4694032052-12">}</span><span class="p" data-group-id="4694032052-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="4694032052-13">(</span><span class="n">Y</span><span class="p" data-group-id="4694032052-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="4694032052-14">(</span><span class="p" data-group-id="4694032052-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4694032052-15">}</span><span class="p" data-group-id="4694032052-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="3412050213-16">(</span><span class="n">Msg</span><span class="p" data-group-id="3412050213-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3412050213-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3412050213-18">(</span><span class="p" data-group-id="3412050213-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="3412050213-17">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="4694032052-16">(</span><span class="n">Msg</span><span class="p" data-group-id="4694032052-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4694032052-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4694032052-18">(</span><span class="p" data-group-id="4694032052-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4694032052-17">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="3412050213-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="3412050213-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="4694032052-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4694032052-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3412050213-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="3412050213-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="3412050213-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3412050213-22">(</span><span class="p" data-group-id="3412050213-22">)</span><span class="p" data-group-id="3412050213-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="3412050213-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3412050213-23">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="3412050213-24">(</span><span class="p" data-group-id="3412050213-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="3412050213-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3412050213-26">[</span><span class="p" data-group-id="3412050213-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3412050213-27">}</span><span class="p" data-group-id="3412050213-26">]</span><span class="p" data-group-id="3412050213-24">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="3412050213-28">(</span><span class="n">Port</span><span class="p" data-group-id="3412050213-28">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="4694032052-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="4694032052-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="4694032052-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4694032052-22">(</span><span class="p" data-group-id="4694032052-22">)</span><span class="p" data-group-id="4694032052-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="4694032052-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="4694032052-23">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="4694032052-24">(</span><span class="p" data-group-id="4694032052-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="4694032052-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4694032052-26">[</span><span class="p" data-group-id="4694032052-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="4694032052-27">}</span><span class="p" data-group-id="4694032052-26">]</span><span class="p" data-group-id="4694032052-24">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="4694032052-28">(</span><span class="n">Port</span><span class="p" data-group-id="4694032052-28">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="3412050213-29">(</span><span class="n">Port</span><span class="p" data-group-id="3412050213-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="4694032052-29">(</span><span class="n">Port</span><span class="p" data-group-id="4694032052-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="3412050213-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="3412050213-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3412050213-31">{</span><span class="nf">self</span><span class="p" data-group-id="3412050213-32">(</span><span class="p" data-group-id="3412050213-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3412050213-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="3412050213-34">(</span><span class="n">Msg</span><span class="p" data-group-id="3412050213-34">)</span><span class="p" data-group-id="3412050213-33">}</span><span class="p" data-group-id="3412050213-31">}</span><span class="p">,</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="4694032052-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4694032052-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4694032052-31">{</span><span class="nf">self</span><span class="p" data-group-id="4694032052-32">(</span><span class="p" data-group-id="4694032052-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4694032052-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="4694032052-34">(</span><span class="n">Msg</span><span class="p" data-group-id="4694032052-34">)</span><span class="p" data-group-id="4694032052-33">}</span><span class="p" data-group-id="4694032052-31">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="3412050213-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3412050213-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3412050213-36">}</span><span class="p" data-group-id="3412050213-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3412050213-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="3412050213-38">(</span><span class="n">Data</span><span class="p" data-group-id="3412050213-38">)</span><span class="p" data-group-id="3412050213-37">}</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="4694032052-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4694032052-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4694032052-36">}</span><span class="p" data-group-id="4694032052-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4694032052-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="4694032052-38">(</span><span class="n">Data</span><span class="p" data-group-id="4694032052-38">)</span><span class="p" data-group-id="4694032052-37">}</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="3412050213-39">(</span><span class="n">Port</span><span class="p" data-group-id="3412050213-39">)</span><span class="p">;</span><span class="w">
│ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="4694032052-39">(</span><span class="n">Port</span><span class="p" data-group-id="4694032052-39">)</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3412050213-40">{</span><span class="nf">self</span><span class="p" data-group-id="3412050213-41">(</span><span class="p" data-group-id="3412050213-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="3412050213-40">}</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4694032052-40">{</span><span class="nf">self</span><span class="p" data-group-id="4694032052-41">(</span><span class="p" data-group-id="4694032052-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="4694032052-40">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="3412050213-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="3412050213-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="3412050213-43">(</span><span class="ss">normal</span><span class="p" data-group-id="3412050213-43">)</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="4694032052-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="4694032052-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="4694032052-43">(</span><span class="ss">normal</span><span class="p" data-group-id="4694032052-43">)</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="3412050213-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="3412050213-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="3412050213-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="3412050213-45">)</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="4694032052-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="4694032052-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="4694032052-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="4694032052-45">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="3412050213-46">(</span><span class="p" data-group-id="3412050213-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3412050213-47">}</span><span class="p" data-group-id="3412050213-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3412050213-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3412050213-48">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="3412050213-49">(</span><span class="p" data-group-id="3412050213-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3412050213-50">}</span><span class="p" data-group-id="3412050213-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3412050213-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3412050213-51">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="4694032052-46">(</span><span class="p" data-group-id="4694032052-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4694032052-47">}</span><span class="p" data-group-id="4694032052-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4694032052-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4694032052-48">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="4694032052-49">(</span><span class="p" data-group-id="4694032052-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4694032052-50">}</span><span class="p" data-group-id="4694032052-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4694032052-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4694032052-51">]</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="3412050213-52">(</span><span class="p" data-group-id="3412050213-53">[</span><span class="n">Int</span><span class="p" data-group-id="3412050213-53">]</span><span class="p" data-group-id="3412050213-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-program" class="section-heading">
│ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="4694032052-52">(</span><span class="p" data-group-id="4694032052-53">[</span><span class="n">Int</span><span class="p" data-group-id="4694032052-53">]</span><span class="p" data-group-id="4694032052-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-program" class="section-heading">
│ │ │    <a href="#c-program" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">C Program</span>
│ │ │  </h2>
│ │ │  <p>On the C side, it is necessary to write functions for receiving and sending data
│ │ │  with 2 byte length indicators from/to Erlang. By default, the C program is to
│ │ │ @@ -333,25 +333,25 @@
│ │ │  and terminates.</p><h2 id="running-the-example" class="section-heading">
│ │ │    <a href="#running-the-example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Running the Example</span>
│ │ │  </h2>
│ │ │  <p><em>Step 1.</em> Compile the C code:</p><pre><code class="text">$ gcc -o extprg complex.c erl_comm.c port.c</code></pre><p><em>Step 2.</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="sc">$ </span><span class="ss">erl</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="6064557705-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="6064557705-1">]</span><span class="w"> </span><span class="p" data-group-id="6064557705-2">[</span><span class="ss">source</span><span class="p" data-group-id="6064557705-2">]</span><span class="w"> </span><span class="p" data-group-id="6064557705-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="6064557705-3">]</span><span class="w"> </span><span class="p" data-group-id="6064557705-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="6064557705-4">]</span><span class="w"> </span><span class="p" data-group-id="6064557705-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="6064557705-5">]</span><span class="w"> </span><span class="p" data-group-id="6064557705-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="6064557705-6">]</span><span class="w"> </span><span class="p" data-group-id="6064557705-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="6064557705-7">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="8294798221-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="8294798221-1">]</span><span class="w"> </span><span class="p" data-group-id="8294798221-2">[</span><span class="ss">source</span><span class="p" data-group-id="8294798221-2">]</span><span class="w"> </span><span class="p" data-group-id="8294798221-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="8294798221-3">]</span><span class="w"> </span><span class="p" data-group-id="8294798221-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="8294798221-4">]</span><span class="w"> </span><span class="p" data-group-id="8294798221-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="8294798221-5">]</span><span class="w"> </span><span class="p" data-group-id="8294798221-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="8294798221-6">]</span><span class="w"> </span><span class="p" data-group-id="8294798221-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="8294798221-7">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="6064557705-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="6064557705-9">(</span><span class="p" data-group-id="6064557705-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="6064557705-8">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="6064557705-10">(</span><span class="ss">complex1</span><span class="p" data-group-id="6064557705-10">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6064557705-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex1</span><span class="p" data-group-id="6064557705-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="6161299837-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="6161299837-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="8294798221-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="8294798221-9">(</span><span class="p" data-group-id="8294798221-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="8294798221-8">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="8294798221-10">(</span><span class="ss">complex1</span><span class="p" data-group-id="8294798221-10">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8294798221-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex1</span><span class="p" data-group-id="8294798221-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="6554395782-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="6554395782-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.34</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="6161299837-2">(</span><span class="mi">3</span><span class="p" data-group-id="6161299837-2">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="6554395782-2">(</span><span class="mi">3</span><span class="p" data-group-id="6554395782-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="6161299837-3">(</span><span class="mi">5</span><span class="p" data-group-id="6161299837-3">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="6554395782-3">(</span><span class="mi">5</span><span class="p" data-group-id="6554395782-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="6161299837-4">(</span><span class="p" data-group-id="6161299837-4">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">complex1</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="6554395782-4">(</span><span class="p" data-group-id="6554395782-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">stop</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="example.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/c_portdriver.html
│ │ │ @@ -151,112 +151,112 @@
│ │ │  <p>Like a port program, the port communicates with an Erlang process. All
│ │ │  communication goes through one Erlang process that is the <em>connected process</em> of
│ │ │  the port driver. Terminating this process closes the port driver.</p><p>Before the port is created, the driver must be loaded. This is done with the
│ │ │  function <a href="../../lib/kernel-10.2.7.2/doc/html/erl_ddll.html#load_driver/2"><code class="inline">erl_ddll:load_driver/2</code></a>, with the name of the shared library as
│ │ │  argument.</p><p>The port is then created using the BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#open_port/2"><code class="inline">open_port/2</code></a>, with the
│ │ │  tuple <code class="inline">{spawn, DriverName}</code> as the first argument. The string <code class="inline">SharedLib</code> is the
│ │ │  name of the port driver. The second argument is a list of options, none in this
│ │ │ -case:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0268198015-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="0268198015-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0268198015-2">(</span><span class="p" data-group-id="0268198015-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0268198015-3">]</span><span class="p" data-group-id="0268198015-2">)</span><span class="p">.</span><span class="w">
│ │ │ +case:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4551646754-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="4551646754-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4551646754-2">(</span><span class="p" data-group-id="4551646754-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4551646754-3">]</span><span class="p" data-group-id="4551646754-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="0268198015-4">(</span><span class="n">SharedLib</span><span class="p" data-group-id="0268198015-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="0268198015-5">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="0268198015-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="4551646754-4">(</span><span class="n">SharedLib</span><span class="p" data-group-id="4551646754-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="4551646754-5">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="4551646754-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0268198015-6">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="0268198015-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="0268198015-7">(</span><span class="p" data-group-id="0268198015-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="0268198015-8">}</span><span class="p" data-group-id="0268198015-7">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="4551646754-6">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="4551646754-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="4551646754-7">(</span><span class="p" data-group-id="4551646754-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="4551646754-8">}</span><span class="p" data-group-id="4551646754-7">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="0268198015-9">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0268198015-10">[</span><span class="n">SharedLib</span><span class="p" data-group-id="0268198015-10">]</span><span class="p" data-group-id="0268198015-9">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="4551646754-9">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4551646754-10">[</span><span class="n">SharedLib</span><span class="p" data-group-id="4551646754-10">]</span><span class="p" data-group-id="4551646754-9">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="0268198015-11">(</span><span class="n">SharedLib</span><span class="p" data-group-id="0268198015-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="nf">register</span><span class="p" data-group-id="0268198015-12">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0268198015-13">(</span><span class="p" data-group-id="0268198015-13">)</span><span class="p" data-group-id="0268198015-12">)</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="0268198015-14">(</span><span class="p" data-group-id="0268198015-15">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="0268198015-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0268198015-16">[</span><span class="p" data-group-id="0268198015-16">]</span><span class="p" data-group-id="0268198015-14">)</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="nf">loop</span><span class="p" data-group-id="0268198015-17">(</span><span class="n">Port</span><span class="p" data-group-id="0268198015-17">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex5:foo/1</code> and <code class="inline">complex5:bar/1</code> can be implemented. Both send a
│ │ │ -message to the <code class="inline">complex</code> process and receive the following reply:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="1701758206-1">(</span><span class="n">X</span><span class="p" data-group-id="1701758206-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="1701758206-2">(</span><span class="p" data-group-id="1701758206-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1701758206-3">}</span><span class="p" data-group-id="1701758206-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="1701758206-4">(</span><span class="n">Y</span><span class="p" data-group-id="1701758206-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="1701758206-5">(</span><span class="p" data-group-id="1701758206-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1701758206-6">}</span><span class="p" data-group-id="1701758206-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="4551646754-11">(</span><span class="n">SharedLib</span><span class="p" data-group-id="4551646754-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="nf">register</span><span class="p" data-group-id="4551646754-12">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4551646754-13">(</span><span class="p" data-group-id="4551646754-13">)</span><span class="p" data-group-id="4551646754-12">)</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="4551646754-14">(</span><span class="p" data-group-id="4551646754-15">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="4551646754-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4551646754-16">[</span><span class="p" data-group-id="4551646754-16">]</span><span class="p" data-group-id="4551646754-14">)</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="nf">loop</span><span class="p" data-group-id="4551646754-17">(</span><span class="n">Port</span><span class="p" data-group-id="4551646754-17">)</span><span class="p">.</span></code></pre><p>Now <code class="inline">complex5:foo/1</code> and <code class="inline">complex5:bar/1</code> can be implemented. Both send a
│ │ │ +message to the <code class="inline">complex</code> process and receive the following reply:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="7070492335-1">(</span><span class="n">X</span><span class="p" data-group-id="7070492335-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="7070492335-2">(</span><span class="p" data-group-id="7070492335-3">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7070492335-3">}</span><span class="p" data-group-id="7070492335-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="7070492335-4">(</span><span class="n">Y</span><span class="p" data-group-id="7070492335-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="7070492335-5">(</span><span class="p" data-group-id="7070492335-6">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7070492335-6">}</span><span class="p" data-group-id="7070492335-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="1701758206-7">(</span><span class="n">Msg</span><span class="p" data-group-id="1701758206-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1701758206-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1701758206-9">(</span><span class="p" data-group-id="1701758206-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1701758206-8">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="7070492335-7">(</span><span class="n">Msg</span><span class="p" data-group-id="7070492335-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7070492335-8">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7070492335-9">(</span><span class="p" data-group-id="7070492335-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="7070492335-8">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="1701758206-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="1701758206-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="7070492335-10">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7070492335-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Result</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process performs the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="3518212718-1">(</span><span class="n">Port</span><span class="p" data-group-id="3518212718-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">complex</code> process performs the following:</p><ul><li>Encodes the message into a sequence of bytes.</li><li>Sends it to the port.</li><li>Waits for a reply.</li><li>Decodes the reply.</li><li>Sends it back to the caller:</li></ul><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="9328875083-1">(</span><span class="n">Port</span><span class="p" data-group-id="9328875083-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="3518212718-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="3518212718-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3518212718-3">{</span><span class="nf">self</span><span class="p" data-group-id="3518212718-4">(</span><span class="p" data-group-id="3518212718-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3518212718-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="3518212718-6">(</span><span class="n">Msg</span><span class="p" data-group-id="3518212718-6">)</span><span class="p" data-group-id="3518212718-5">}</span><span class="p" data-group-id="3518212718-3">}</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9328875083-2">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="9328875083-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9328875083-3">{</span><span class="nf">self</span><span class="p" data-group-id="9328875083-4">(</span><span class="p" data-group-id="9328875083-4">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9328875083-5">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="9328875083-6">(</span><span class="n">Msg</span><span class="p" data-group-id="9328875083-6">)</span><span class="p" data-group-id="9328875083-5">}</span><span class="p" data-group-id="9328875083-3">}</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="k">receive</span><span class="w">
│ │ │ -                </span><span class="p" data-group-id="3518212718-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3518212718-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3518212718-8">}</span><span class="p" data-group-id="3518212718-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3518212718-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="3518212718-10">(</span><span class="n">Data</span><span class="p" data-group-id="3518212718-10">)</span><span class="p" data-group-id="3518212718-9">}</span><span class="w">
│ │ │ +                </span><span class="p" data-group-id="9328875083-7">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9328875083-8">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9328875083-8">}</span><span class="p" data-group-id="9328875083-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9328875083-9">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="9328875083-10">(</span><span class="n">Data</span><span class="p" data-group-id="9328875083-10">)</span><span class="p" data-group-id="9328875083-9">}</span><span class="w">
│ │ │              </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="3518212718-11">(</span><span class="n">Port</span><span class="p" data-group-id="3518212718-11">)</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="9328875083-11">(</span><span class="n">Port</span><span class="p" data-group-id="9328875083-11">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Assuming that both the arguments and the results from the C functions are less
│ │ │  than 256, a simple encoding/decoding scheme is employed. In this scheme, <code class="inline">foo</code>
│ │ │  is represented by byte 1, <code class="inline">bar</code> is represented by 2, and the argument/result is
│ │ │ -represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="1613829367-1">(</span><span class="p" data-group-id="1613829367-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1613829367-2">}</span><span class="p" data-group-id="1613829367-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1613829367-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1613829367-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="1613829367-4">(</span><span class="p" data-group-id="1613829367-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1613829367-5">}</span><span class="p" data-group-id="1613829367-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1613829367-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1613829367-6">]</span><span class="p">.</span><span class="w">
│ │ │ +represented by a single byte as well:</p><pre><code class="makeup erlang" translate="no"><span class="nf">encode</span><span class="p" data-group-id="7869911680-1">(</span><span class="p" data-group-id="7869911680-2">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7869911680-2">}</span><span class="p" data-group-id="7869911680-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7869911680-3">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7869911680-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="7869911680-4">(</span><span class="p" data-group-id="7869911680-5">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7869911680-5">}</span><span class="p" data-group-id="7869911680-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7869911680-6">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7869911680-6">]</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="1613829367-7">(</span><span class="p" data-group-id="1613829367-8">[</span><span class="n">Int</span><span class="p" data-group-id="1613829367-8">]</span><span class="p" data-group-id="1613829367-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functions for stopping the port and
│ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="7869911680-7">(</span><span class="p" data-group-id="7869911680-8">[</span><span class="n">Int</span><span class="p" data-group-id="7869911680-8">]</span><span class="p" data-group-id="7869911680-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>The resulting Erlang program, including functions for stopping the port and
│ │ │  detecting port failures, is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4909287132-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="4909287132-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4909287132-2">(</span><span class="p" data-group-id="4909287132-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4909287132-3">]</span><span class="p" data-group-id="4909287132-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4909287132-4">(</span><span class="p" data-group-id="4909287132-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4909287132-5">]</span><span class="p" data-group-id="4909287132-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8263668858-1">(</span><span class="ss">complex5</span><span class="p" data-group-id="8263668858-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8263668858-2">(</span><span class="p" data-group-id="8263668858-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8263668858-3">]</span><span class="p" data-group-id="8263668858-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8263668858-4">(</span><span class="p" data-group-id="8263668858-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8263668858-5">]</span><span class="p" data-group-id="8263668858-4">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="4909287132-6">(</span><span class="n">SharedLib</span><span class="p" data-group-id="4909287132-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="4909287132-7">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="4909287132-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="8263668858-6">(</span><span class="n">SharedLib</span><span class="p" data-group-id="8263668858-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="8263668858-7">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="8263668858-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │  	</span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="4909287132-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="4909287132-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -	</span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="4909287132-9">(</span><span class="p" data-group-id="4909287132-10">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="4909287132-10">}</span><span class="p" data-group-id="4909287132-9">)</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="8263668858-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="8263668858-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ +	</span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="8263668858-9">(</span><span class="p" data-group-id="8263668858-10">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="8263668858-10">}</span><span class="p" data-group-id="8263668858-9">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="4909287132-11">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4909287132-12">[</span><span class="n">SharedLib</span><span class="p" data-group-id="4909287132-12">]</span><span class="p" data-group-id="4909287132-11">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="8263668858-11">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8263668858-12">[</span><span class="n">SharedLib</span><span class="p" data-group-id="8263668858-12">]</span><span class="p" data-group-id="8263668858-11">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="4909287132-13">(</span><span class="n">SharedLib</span><span class="p" data-group-id="4909287132-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="4909287132-14">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4909287132-15">(</span><span class="p" data-group-id="4909287132-15">)</span><span class="p" data-group-id="4909287132-14">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="4909287132-16">(</span><span class="p" data-group-id="4909287132-17">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="4909287132-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4909287132-18">[</span><span class="p" data-group-id="4909287132-18">]</span><span class="p" data-group-id="4909287132-16">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="4909287132-19">(</span><span class="n">Port</span><span class="p" data-group-id="4909287132-19">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="8263668858-13">(</span><span class="n">SharedLib</span><span class="p" data-group-id="8263668858-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="8263668858-14">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8263668858-15">(</span><span class="p" data-group-id="8263668858-15">)</span><span class="p" data-group-id="8263668858-14">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="8263668858-16">(</span><span class="p" data-group-id="8263668858-17">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">SharedLib</span><span class="p" data-group-id="8263668858-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8263668858-18">[</span><span class="p" data-group-id="8263668858-18">]</span><span class="p" data-group-id="8263668858-16">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="8263668858-19">(</span><span class="n">Port</span><span class="p" data-group-id="8263668858-19">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="4909287132-20">(</span><span class="p" data-group-id="4909287132-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="8263668858-20">(</span><span class="p" data-group-id="8263668858-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="4909287132-21">(</span><span class="n">X</span><span class="p" data-group-id="4909287132-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="4909287132-22">(</span><span class="p" data-group-id="4909287132-23">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4909287132-23">}</span><span class="p" data-group-id="4909287132-22">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="4909287132-24">(</span><span class="n">Y</span><span class="p" data-group-id="4909287132-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="4909287132-25">(</span><span class="p" data-group-id="4909287132-26">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4909287132-26">}</span><span class="p" data-group-id="4909287132-25">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="8263668858-21">(</span><span class="n">X</span><span class="p" data-group-id="8263668858-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="8263668858-22">(</span><span class="p" data-group-id="8263668858-23">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8263668858-23">}</span><span class="p" data-group-id="8263668858-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="8263668858-24">(</span><span class="n">Y</span><span class="p" data-group-id="8263668858-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="8263668858-25">(</span><span class="p" data-group-id="8263668858-26">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8263668858-26">}</span><span class="p" data-group-id="8263668858-25">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="4909287132-27">(</span><span class="n">Msg</span><span class="p" data-group-id="4909287132-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4909287132-28">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4909287132-29">(</span><span class="p" data-group-id="4909287132-29">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4909287132-28">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="8263668858-27">(</span><span class="n">Msg</span><span class="p" data-group-id="8263668858-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8263668858-28">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8263668858-29">(</span><span class="p" data-group-id="8263668858-29">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="8263668858-28">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="4909287132-30">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4909287132-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="8263668858-30">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="8263668858-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="4909287132-31">(</span><span class="n">Port</span><span class="p" data-group-id="4909287132-31">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="8263668858-31">(</span><span class="n">Port</span><span class="p" data-group-id="8263668858-31">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="4909287132-32">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4909287132-32">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4909287132-33">{</span><span class="nf">self</span><span class="p" data-group-id="4909287132-34">(</span><span class="p" data-group-id="4909287132-34">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4909287132-35">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="4909287132-36">(</span><span class="n">Msg</span><span class="p" data-group-id="4909287132-36">)</span><span class="p" data-group-id="4909287132-35">}</span><span class="p" data-group-id="4909287132-33">}</span><span class="p">,</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="8263668858-32">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="8263668858-32">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8263668858-33">{</span><span class="nf">self</span><span class="p" data-group-id="8263668858-34">(</span><span class="p" data-group-id="8263668858-34">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8263668858-35">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="8263668858-36">(</span><span class="n">Msg</span><span class="p" data-group-id="8263668858-36">)</span><span class="p" data-group-id="8263668858-35">}</span><span class="p" data-group-id="8263668858-33">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="4909287132-37">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4909287132-38">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4909287132-38">}</span><span class="p" data-group-id="4909287132-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4909287132-39">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="4909287132-40">(</span><span class="n">Data</span><span class="p" data-group-id="4909287132-40">)</span><span class="p" data-group-id="4909287132-39">}</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="8263668858-37">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8263668858-38">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8263668858-38">}</span><span class="p" data-group-id="8263668858-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8263668858-39">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="8263668858-40">(</span><span class="n">Data</span><span class="p" data-group-id="8263668858-40">)</span><span class="p" data-group-id="8263668858-39">}</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="4909287132-41">(</span><span class="n">Port</span><span class="p" data-group-id="4909287132-41">)</span><span class="p">;</span><span class="w">
│ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="8263668858-41">(</span><span class="n">Port</span><span class="p" data-group-id="8263668858-41">)</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4909287132-42">{</span><span class="nf">self</span><span class="p" data-group-id="4909287132-43">(</span><span class="p" data-group-id="4909287132-43">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="4909287132-42">}</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8263668858-42">{</span><span class="nf">self</span><span class="p" data-group-id="8263668858-43">(</span><span class="p" data-group-id="8263668858-43">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="8263668858-42">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="4909287132-44">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="4909287132-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="4909287132-45">(</span><span class="ss">normal</span><span class="p" data-group-id="4909287132-45">)</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="8263668858-44">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="8263668858-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="8263668858-45">(</span><span class="ss">normal</span><span class="p" data-group-id="8263668858-45">)</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="4909287132-46">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="4909287132-46">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4909287132-47">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4909287132-48">[</span><span class="n">Reason</span><span class="p" data-group-id="4909287132-48">]</span><span class="p" data-group-id="4909287132-47">)</span><span class="p">,</span><span class="w">
│ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="4909287132-49">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="4909287132-49">)</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="8263668858-46">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="8263668858-46">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8263668858-47">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8263668858-48">[</span><span class="n">Reason</span><span class="p" data-group-id="8263668858-48">]</span><span class="p" data-group-id="8263668858-47">)</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="8263668858-49">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="8263668858-49">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="4909287132-50">(</span><span class="p" data-group-id="4909287132-51">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4909287132-51">}</span><span class="p" data-group-id="4909287132-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4909287132-52">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="4909287132-52">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="4909287132-53">(</span><span class="p" data-group-id="4909287132-54">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4909287132-54">}</span><span class="p" data-group-id="4909287132-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4909287132-55">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4909287132-55">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="8263668858-50">(</span><span class="p" data-group-id="8263668858-51">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8263668858-51">}</span><span class="p" data-group-id="8263668858-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8263668858-52">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="8263668858-52">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="8263668858-53">(</span><span class="p" data-group-id="8263668858-54">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8263668858-54">}</span><span class="p" data-group-id="8263668858-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8263668858-55">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8263668858-55">]</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="4909287132-56">(</span><span class="p" data-group-id="4909287132-57">[</span><span class="n">Int</span><span class="p" data-group-id="4909287132-57">]</span><span class="p" data-group-id="4909287132-56">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-driver" class="section-heading">
│ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="8263668858-56">(</span><span class="p" data-group-id="8263668858-57">[</span><span class="n">Int</span><span class="p" data-group-id="8263668858-57">]</span><span class="p" data-group-id="8263668858-56">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><h2 id="c-driver" class="section-heading">
│ │ │    <a href="#c-driver" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">C Driver</span>
│ │ │  </h2>
│ │ │  <p>The C driver is a module that is compiled and linked into a shared library. It
│ │ │  uses a driver structure and includes the header file <code class="inline">erl_driver.h</code>.</p><p>The driver structure is filled with the driver name and function pointers. It is
│ │ │ @@ -347,25 +347,25 @@
│ │ │    <a href="#running-the-example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Running the Example</span>
│ │ │  </h2>
│ │ │  <p><em>Step 1.</em> Compile the C code:</p><pre><code class="text">unix&gt; gcc -o example_drv.so -fpic -shared complex.c port_driver.c
│ │ │  windows&gt; cl -LD -MD -Fe example_drv.dll complex.c port_driver.c</code></pre><p><em>Step 2.</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="ss">erl</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="9542452105-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="9542452105-1">]</span><span class="w"> </span><span class="p" data-group-id="9542452105-2">[</span><span class="ss">source</span><span class="p" data-group-id="9542452105-2">]</span><span class="w"> </span><span class="p" data-group-id="9542452105-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="9542452105-3">]</span><span class="w"> </span><span class="p" data-group-id="9542452105-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="9542452105-4">]</span><span class="w"> </span><span class="p" data-group-id="9542452105-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="9542452105-5">]</span><span class="w"> </span><span class="p" data-group-id="9542452105-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="9542452105-6">]</span><span class="w"> </span><span class="p" data-group-id="9542452105-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="9542452105-7">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="0194288433-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="0194288433-1">]</span><span class="w"> </span><span class="p" data-group-id="0194288433-2">[</span><span class="ss">source</span><span class="p" data-group-id="0194288433-2">]</span><span class="w"> </span><span class="p" data-group-id="0194288433-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="0194288433-3">]</span><span class="w"> </span><span class="p" data-group-id="0194288433-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0194288433-4">]</span><span class="w"> </span><span class="p" data-group-id="0194288433-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="0194288433-5">]</span><span class="w"> </span><span class="p" data-group-id="0194288433-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="0194288433-6">]</span><span class="w"> </span><span class="p" data-group-id="0194288433-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="0194288433-7">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="9542452105-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="9542452105-9">(</span><span class="p" data-group-id="9542452105-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="9542452105-8">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="9542452105-10">(</span><span class="ss">complex5</span><span class="p" data-group-id="9542452105-10">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9542452105-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex5</span><span class="p" data-group-id="9542452105-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7516986082-1">(</span><span class="s">&quot;example_drv&quot;</span><span class="p" data-group-id="7516986082-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="0194288433-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="0194288433-9">(</span><span class="p" data-group-id="0194288433-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="0194288433-8">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="0194288433-10">(</span><span class="ss">complex5</span><span class="p" data-group-id="0194288433-10">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0194288433-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex5</span><span class="p" data-group-id="0194288433-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7797958439-1">(</span><span class="s">&quot;example_drv&quot;</span><span class="p" data-group-id="7797958439-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.34</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="7516986082-2">(</span><span class="mi">3</span><span class="p" data-group-id="7516986082-2">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="7797958439-2">(</span><span class="mi">3</span><span class="p" data-group-id="7797958439-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="7516986082-3">(</span><span class="mi">5</span><span class="p" data-group-id="7516986082-3">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="7797958439-3">(</span><span class="mi">5</span><span class="p" data-group-id="7797958439-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="7516986082-4">(</span><span class="p" data-group-id="7516986082-4">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">complex5</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="7797958439-4">(</span><span class="p" data-group-id="7797958439-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">stop</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="erl_interface.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/code_loading.html
│ │ │ @@ -122,16 +122,16 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Compilation</span>
│ │ │  </h2>
│ │ │  <p>Erlang programs must be <em>compiled</em> to object code. The compiler can generate a
│ │ │  new file that contains the object code. The current abstract machine, which runs
│ │ │  the object code, is called BEAM, therefore the object files get the suffix
│ │ │ -<code class="inline">.beam</code>. The compiler can also generate a binary which can be loaded directly.</p><p>The compiler is located in the module <a href="../../lib/compiler-8.6.1.2/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><pre><code class="makeup erlang" translate="no"><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="9126133453-1">(</span><span class="n">Module</span><span class="p" data-group-id="9126133453-1">)</span><span class="w">
│ │ │ -</span><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="9126133453-2">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="9126133453-2">)</span></code></pre><p>The Erlang shell understands the command <code class="inline">c(Module)</code>, which both compiles and
│ │ │ +<code class="inline">.beam</code>. The compiler can also generate a binary which can be loaded directly.</p><p>The compiler is located in the module <a href="../../lib/compiler-8.6.1.2/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><pre><code class="makeup erlang" translate="no"><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="3111222534-1">(</span><span class="n">Module</span><span class="p" data-group-id="3111222534-1">)</span><span class="w">
│ │ │ +</span><span class="nc">compile</span><span class="p">:</span><span class="nf">file</span><span class="p" data-group-id="3111222534-2">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="3111222534-2">)</span></code></pre><p>The Erlang shell understands the command <code class="inline">c(Module)</code>, which both compiles and
│ │ │  loads <code class="inline">Module</code>.</p><p>There is also a module <code class="inline">make</code>, which provides a set of functions similar to the
│ │ │  UNIX type Make functions, see module <a href="../../lib/tools-4.1.1/doc/html/make.html"><code class="inline">make</code></a> in Tools.</p><p>The compiler can also be accessed from the OS prompt using the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erl_cmd.html">erl</a> executable in ERTS.</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -compile Module1...ModuleN</span><span class="w">
│ │ │  </span><span class="c1">% erl -make</span></code></pre><p>The <code class="inline">erlc</code> program provides way to compile modules from the OS
│ │ │  shell, see the <a href="../../erts-15.2.7.3/doc/html/erlc_cmd.html">erlc</a> executable in ERTS. It
│ │ │  understands a number of flags that can be used to define macros, add search
│ │ │  paths for include files, and more.</p><pre><code class="text">% erlc &lt;flags&gt; File1.erl...FileN.erl</code></pre><p><a href="" id="loading"></a></p><h2 id="code-loading" class="section-heading">
│ │ │ @@ -156,54 +156,54 @@
│ │ │  When a module is loaded into the system for the first time, the code becomes
│ │ │  'current'. If then a new instance of the module is loaded, the code of the
│ │ │  previous instance becomes 'old' and the new instance becomes 'current'.</p><p>Both old and current code is valid, and can be evaluated concurrently. Fully
│ │ │  qualified function calls always refer to current code. Old code can still be
│ │ │  evaluated because of processes lingering in the old code.</p><p>If a third instance of the module is loaded, the code server removes (purges)
│ │ │  the old code and any processes lingering in it is terminated. Then the third
│ │ │  instance becomes 'current' and the previously current code becomes 'old'.</p><p>To change from old code to current code, a process must make a fully qualified
│ │ │ -function call.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0078517185-1">(</span><span class="ss">m</span><span class="p" data-group-id="0078517185-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0078517185-2">(</span><span class="p" data-group-id="0078517185-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0078517185-3">]</span><span class="p" data-group-id="0078517185-2">)</span><span class="p">.</span><span class="w">
│ │ │ +function call.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7428154286-1">(</span><span class="ss">m</span><span class="p" data-group-id="7428154286-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7428154286-2">(</span><span class="p" data-group-id="7428154286-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7428154286-3">]</span><span class="p" data-group-id="7428154286-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="0078517185-4">(</span><span class="p" data-group-id="0078517185-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="7428154286-4">(</span><span class="p" data-group-id="7428154286-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">code_switch</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">m</span><span class="p">:</span><span class="nf">loop</span><span class="p" data-group-id="0078517185-5">(</span><span class="p" data-group-id="0078517185-5">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="nc">m</span><span class="p">:</span><span class="nf">loop</span><span class="p" data-group-id="7428154286-5">(</span><span class="p" data-group-id="7428154286-5">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="n">Msg</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="0078517185-6">(</span><span class="p" data-group-id="0078517185-6">)</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="7428154286-6">(</span><span class="p" data-group-id="7428154286-6">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>To make the process change code, send the message <code class="inline">code_switch</code> to it. The
│ │ │  process then makes a fully qualified call to <code class="inline">m:loop()</code> and changes to current
│ │ │  code. Notice that <code class="inline">m:loop/0</code> must be exported.</p><p>For code replacement of funs to work, use the syntax
│ │ │  <code class="inline">fun Module:FunctionName/Arity</code>.</p><p><a href="" id="on_load"></a></p><h2 id="running-a-function-when-a-module-is-loaded" class="section-heading">
│ │ │    <a href="#running-a-function-when-a-module-is-loaded" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Running a Function When a Module is Loaded</span>
│ │ │  </h2>
│ │ │  <p>The <code class="inline">-on_load()</code> directive names a function that is to be run automatically when
│ │ │ -a module is loaded.</p><p>Its syntax is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="2722225465-1">(</span><span class="n">Name</span><span class="o">/</span><span class="mi">0</span><span class="p" data-group-id="2722225465-1">)</span><span class="p">.</span></code></pre><p>It is not necessary to export the function. It is called in a freshly spawned
│ │ │ +a module is loaded.</p><p>Its syntax is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="5583299379-1">(</span><span class="n">Name</span><span class="o">/</span><span class="mi">0</span><span class="p" data-group-id="5583299379-1">)</span><span class="p">.</span></code></pre><p>It is not necessary to export the function. It is called in a freshly spawned
│ │ │  process (which terminates as soon as the function returns).</p><p>The function must return <code class="inline">ok</code> if the module is to become the new current code
│ │ │  for the module and become callable.</p><p>Returning any other value or generating an exception causes the new code to be
│ │ │  unloaded. If the return value is not an atom, a warning error report is sent to
│ │ │  the error logger.</p><p>If there already is current code for the module, that code will remain current
│ │ │  and can be called until the <code class="inline">on_load</code> function has returned. If the <code class="inline">on_load</code>
│ │ │  function fails, the current code (if any) will remain current. If there is no
│ │ │  current code for a module, any process that makes an external call to the module
│ │ │  before the <code class="inline">on_load</code> function has finished will be suspended until the <code class="inline">on_load</code>
│ │ │  function have finished.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 19, if the <code class="inline">on_load</code> function failed, any previously current
│ │ │  code would become old, essentially leaving the system without any working and
│ │ │  reachable instance of the module.</p></section><p>In embedded mode, first all modules are loaded. Then all <code class="inline">on_load</code> functions are
│ │ │  called. The system is terminated unless all of the <code class="inline">on_load</code> functions return
│ │ │ -<code class="inline">ok</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7713133292-1">(</span><span class="ss">m</span><span class="p" data-group-id="7713133292-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="7713133292-2">(</span><span class="ss">load_my_nifs</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7713133292-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">ok</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2515070626-1">(</span><span class="ss">m</span><span class="p" data-group-id="2515070626-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="2515070626-2">(</span><span class="ss">load_my_nifs</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2515070626-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">load_my_nifs</span><span class="p" data-group-id="7713133292-3">(</span><span class="p" data-group-id="7713133292-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">load_my_nifs</span><span class="p" data-group-id="2515070626-3">(</span><span class="p" data-group-id="2515070626-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">NifPath</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">    </span><span class="c1">%Set up the path to the NIF library.</span><span class="w">
│ │ │      </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">       </span><span class="c1">%Initialize the Info term</span><span class="w">
│ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="7713133292-4">(</span><span class="n">NifPath</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="7713133292-4">)</span><span class="p">.</span></code></pre><p>If the call to <a href="../../erts-15.2.7.3/doc/html/erlang.html#load_nif/2"><code class="inline">erlang:load_nif/2</code></a> fails, the module is unloaded and a warning
│ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="2515070626-4">(</span><span class="n">NifPath</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="2515070626-4">)</span><span class="p">.</span></code></pre><p>If the call to <a href="../../erts-15.2.7.3/doc/html/erlang.html#load_nif/2"><code class="inline">erlang:load_nif/2</code></a> fails, the module is unloaded and a warning
│ │ │  report is sent to the error loader.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="distributed.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/commoncaveats.html
│ │ │ @@ -118,31 +118,31 @@
│ │ │  <p>This section lists a few constructs to watch out for.</p><h2 id="operator" class="section-heading">
│ │ │    <a href="#operator" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Operator <code class="inline">++</code></span>
│ │ │  </h2>
│ │ │  <p>The <code class="inline">++</code> operator copies its left-hand side operand. That is clearly
│ │ │ -seen if we do our own implementation in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_plus_plus</span><span class="p" data-group-id="7641607827-1">(</span><span class="p" data-group-id="7641607827-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7641607827-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="7641607827-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7641607827-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="7641607827-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="7641607827-4">)</span><span class="p" data-group-id="7641607827-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="7641607827-5">(</span><span class="p" data-group-id="7641607827-6">[</span><span class="p" data-group-id="7641607827-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="7641607827-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Tail</span><span class="p">.</span></code></pre><p>We must be careful how we use <code class="inline">++</code> in a loop. First is how not to use it:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_reverse</span><span class="p" data-group-id="4216226701-1">(</span><span class="p" data-group-id="4216226701-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4216226701-2">]</span><span class="p" data-group-id="4216226701-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">naive_reverse</span><span class="p" data-group-id="4216226701-3">(</span><span class="n">T</span><span class="p" data-group-id="4216226701-3">)</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="4216226701-4">[</span><span class="n">H</span><span class="p" data-group-id="4216226701-4">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">naive_reverse</span><span class="p" data-group-id="4216226701-5">(</span><span class="p" data-group-id="4216226701-6">[</span><span class="p" data-group-id="4216226701-6">]</span><span class="p" data-group-id="4216226701-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4216226701-7">[</span><span class="p" data-group-id="4216226701-7">]</span><span class="p">.</span></code></pre><p>As the <code class="inline">++</code> operator copies its left-hand side operand, the growing
│ │ │ -result is copied repeatedly, leading to quadratic complexity.</p><p>On the other hand, using <code class="inline">++</code> in loop like this is perfectly fine:</p><p><strong>OK</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="9423088976-1">(</span><span class="n">List</span><span class="p" data-group-id="9423088976-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="9423088976-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9423088976-3">[</span><span class="p" data-group-id="9423088976-3">]</span><span class="p" data-group-id="9423088976-2">)</span><span class="p">.</span><span class="w">
│ │ │ +seen if we do our own implementation in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_plus_plus</span><span class="p" data-group-id="2964762358-1">(</span><span class="p" data-group-id="2964762358-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2964762358-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="2964762358-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2964762358-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="2964762358-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="2964762358-4">)</span><span class="p" data-group-id="2964762358-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">my_plus_plus</span><span class="p" data-group-id="2964762358-5">(</span><span class="p" data-group-id="2964762358-6">[</span><span class="p" data-group-id="2964762358-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="2964762358-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Tail</span><span class="p">.</span></code></pre><p>We must be careful how we use <code class="inline">++</code> in a loop. First is how not to use it:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_reverse</span><span class="p" data-group-id="3745616820-1">(</span><span class="p" data-group-id="3745616820-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3745616820-2">]</span><span class="p" data-group-id="3745616820-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">naive_reverse</span><span class="p" data-group-id="3745616820-3">(</span><span class="n">T</span><span class="p" data-group-id="3745616820-3">)</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="3745616820-4">[</span><span class="n">H</span><span class="p" data-group-id="3745616820-4">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">naive_reverse</span><span class="p" data-group-id="3745616820-5">(</span><span class="p" data-group-id="3745616820-6">[</span><span class="p" data-group-id="3745616820-6">]</span><span class="p" data-group-id="3745616820-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3745616820-7">[</span><span class="p" data-group-id="3745616820-7">]</span><span class="p">.</span></code></pre><p>As the <code class="inline">++</code> operator copies its left-hand side operand, the growing
│ │ │ +result is copied repeatedly, leading to quadratic complexity.</p><p>On the other hand, using <code class="inline">++</code> in loop like this is perfectly fine:</p><p><strong>OK</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="0818410692-1">(</span><span class="n">List</span><span class="p" data-group-id="0818410692-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="0818410692-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0818410692-3">[</span><span class="p" data-group-id="0818410692-3">]</span><span class="p" data-group-id="0818410692-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="9423088976-4">(</span><span class="p" data-group-id="9423088976-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9423088976-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="9423088976-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="9423088976-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9423088976-7">[</span><span class="n">H</span><span class="p" data-group-id="9423088976-7">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="9423088976-6">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="9423088976-8">(</span><span class="p" data-group-id="9423088976-9">[</span><span class="p" data-group-id="9423088976-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="9423088976-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="0818410692-4">(</span><span class="p" data-group-id="0818410692-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0818410692-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="0818410692-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="0818410692-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0818410692-7">[</span><span class="n">H</span><span class="p" data-group-id="0818410692-7">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="0818410692-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">naive_but_ok_reverse</span><span class="p" data-group-id="0818410692-8">(</span><span class="p" data-group-id="0818410692-9">[</span><span class="p" data-group-id="0818410692-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="0818410692-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>Each list element is copied only once. The growing result <code class="inline">Acc</code> is the right-hand
│ │ │ -side operand, which it is <em>not</em> copied.</p><p>Experienced Erlang programmers would probably write as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">vanilla_reverse</span><span class="p" data-group-id="7521449924-1">(</span><span class="p" data-group-id="7521449924-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7521449924-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7521449924-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="7521449924-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7521449924-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="7521449924-4">]</span><span class="p" data-group-id="7521449924-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="7521449924-5">(</span><span class="p" data-group-id="7521449924-6">[</span><span class="p" data-group-id="7521449924-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7521449924-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +side operand, which it is <em>not</em> copied.</p><p>Experienced Erlang programmers would probably write as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">vanilla_reverse</span><span class="p" data-group-id="7995841149-1">(</span><span class="p" data-group-id="7995841149-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7995841149-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7995841149-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="7995841149-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7995841149-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="7995841149-4">]</span><span class="p" data-group-id="7995841149-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">vanilla_reverse</span><span class="p" data-group-id="7995841149-5">(</span><span class="p" data-group-id="7995841149-6">[</span><span class="p" data-group-id="7995841149-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7995841149-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">.</span></code></pre><p>In principle, this is slightly more efficient because the list element <code class="inline">[H]</code>
│ │ │  is not built before being copied and discarded. In practice, the compiler
│ │ │  rewrites <code class="inline">[H] ++ Acc</code> to <code class="inline">[H|Acc]</code>.</p><h2 id="timer-module" class="section-heading">
│ │ │    <a href="#timer-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Timer Module</span>
│ │ │ @@ -160,77 +160,77 @@
│ │ │  therefore harmless.</p><h2 id="accidental-copying-and-loss-of-sharing" class="section-heading">
│ │ │    <a href="#accidental-copying-and-loss-of-sharing" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Accidental Copying and Loss of Sharing</span>
│ │ │  </h2>
│ │ │  <p>When spawning a new process using a fun, one can accidentally copy more data to
│ │ │ -the process than intended. For example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental1</span><span class="p" data-group-id="8783895437-1">(</span><span class="n">State</span><span class="p" data-group-id="8783895437-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="8783895437-2">(</span><span class="nf">fun</span><span class="p" data-group-id="8783895437-3">(</span><span class="p" data-group-id="8783895437-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8783895437-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8783895437-5">[</span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">info</span><span class="p" data-group-id="8783895437-5">]</span><span class="p" data-group-id="8783895437-4">)</span><span class="w">
│ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="8783895437-2">)</span><span class="p">.</span></code></pre><p>The code in the fun will extract one element from the record and print it. The
│ │ │ +the process than intended. For example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental1</span><span class="p" data-group-id="5521505237-1">(</span><span class="n">State</span><span class="p" data-group-id="5521505237-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="5521505237-2">(</span><span class="nf">fun</span><span class="p" data-group-id="5521505237-3">(</span><span class="p" data-group-id="5521505237-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5521505237-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5521505237-5">[</span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">info</span><span class="p" data-group-id="5521505237-5">]</span><span class="p" data-group-id="5521505237-4">)</span><span class="w">
│ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="5521505237-2">)</span><span class="p">.</span></code></pre><p>The code in the fun will extract one element from the record and print it. The
│ │ │  rest of the <code class="inline">state</code> record is not used. However, when the <a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn/1"><code class="inline">spawn/1</code></a>
│ │ │ -function is executed, the entire record is copied to the newly created process.</p><p>The same kind of problem can happen with a map:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental2</span><span class="p" data-group-id="8986747882-1">(</span><span class="n">State</span><span class="p" data-group-id="8986747882-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="8986747882-2">(</span><span class="nf">fun</span><span class="p" data-group-id="8986747882-3">(</span><span class="p" data-group-id="8986747882-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8986747882-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8986747882-5">[</span><span class="nf">map_get</span><span class="p" data-group-id="8986747882-6">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="8986747882-6">)</span><span class="p" data-group-id="8986747882-5">]</span><span class="p" data-group-id="8986747882-4">)</span><span class="w">
│ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="8986747882-2">)</span><span class="p">.</span></code></pre><p>In the following example (part of a module implementing the <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html"><code class="inline">gen_server</code></a>
│ │ │ -behavior) the created fun is sent to another process:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="9489896087-1">(</span><span class="ss">give_me_a_fun</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9489896087-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="9489896087-2">(</span><span class="p" data-group-id="9489896087-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="nb">size</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9489896087-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9489896087-3">}</span><span class="p">.</span></code></pre><p>How bad that unnecessary copy is depends on the contents of the record or the
│ │ │ -map.</p><p>For example, if the <code class="inline">state</code> record is initialized like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init1</span><span class="p" data-group-id="1564865391-1">(</span><span class="p" data-group-id="1564865391-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="1564865391-2">{</span><span class="ss">data</span><span class="o">=</span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="1564865391-3">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">10000</span><span class="p" data-group-id="1564865391-3">)</span><span class="p" data-group-id="1564865391-2">}</span><span class="p">.</span></code></pre><p>a list with 10000 elements (or about 20000 heap words) will be copied to the
│ │ │ +function is executed, the entire record is copied to the newly created process.</p><p>The same kind of problem can happen with a map:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">accidental2</span><span class="p" data-group-id="7173328107-1">(</span><span class="n">State</span><span class="p" data-group-id="7173328107-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7173328107-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7173328107-3">(</span><span class="p" data-group-id="7173328107-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7173328107-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7173328107-5">[</span><span class="nf">map_get</span><span class="p" data-group-id="7173328107-6">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7173328107-6">)</span><span class="p" data-group-id="7173328107-5">]</span><span class="p" data-group-id="7173328107-4">)</span><span class="w">
│ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="7173328107-2">)</span><span class="p">.</span></code></pre><p>In the following example (part of a module implementing the <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html"><code class="inline">gen_server</code></a>
│ │ │ +behavior) the created fun is sent to another process:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="0680851373-1">(</span><span class="ss">give_me_a_fun</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="0680851373-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="0680851373-2">(</span><span class="p" data-group-id="0680851373-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="nb">size</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0680851373-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="0680851373-3">}</span><span class="p">.</span></code></pre><p>How bad that unnecessary copy is depends on the contents of the record or the
│ │ │ +map.</p><p>For example, if the <code class="inline">state</code> record is initialized like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init1</span><span class="p" data-group-id="0352805214-1">(</span><span class="p" data-group-id="0352805214-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="0352805214-2">{</span><span class="ss">data</span><span class="o">=</span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0352805214-3">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">10000</span><span class="p" data-group-id="0352805214-3">)</span><span class="p" data-group-id="0352805214-2">}</span><span class="p">.</span></code></pre><p>a list with 10000 elements (or about 20000 heap words) will be copied to the
│ │ │  newly created process.</p><p>An unnecessary copy of 10000 element list can be bad enough, but it can get even
│ │ │  worse if the <code class="inline">state</code> record contains <em>shared subterms</em>. Here is a simple example
│ │ │ -of a term with a shared subterm:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2899836794-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="2899836794-1">}</span></code></pre><p>When a term is copied to another process, sharing of subterms will be lost and
│ │ │ -the copied term can be many times larger than the original term. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init2</span><span class="p" data-group-id="6572681263-1">(</span><span class="p" data-group-id="6572681263-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SharedSubTerms</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="6572681263-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6572681263-3">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="6572681263-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6572681263-4">[</span><span class="n">A</span><span class="p">|</span><span class="n">A</span><span class="p" data-group-id="6572681263-4">]</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6572681263-5">[</span><span class="mi">0</span><span class="p" data-group-id="6572681263-5">]</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="6572681263-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">15</span><span class="p" data-group-id="6572681263-6">)</span><span class="p" data-group-id="6572681263-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="6572681263-7">{</span><span class="ss">data</span><span class="o">=</span><span class="n">Shared</span><span class="p" data-group-id="6572681263-7">}</span><span class="p">.</span></code></pre><p>In the process that calls <code class="inline">init2/0</code>, the size of the <code class="inline">data</code> field in the <code class="inline">state</code>
│ │ │ +of a term with a shared subterm:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3869059153-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="3869059153-1">}</span></code></pre><p>When a term is copied to another process, sharing of subterms will be lost and
│ │ │ +the copied term can be many times larger than the original term. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init2</span><span class="p" data-group-id="0044749820-1">(</span><span class="p" data-group-id="0044749820-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SharedSubTerms</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="0044749820-2">(</span><span class="nf">fun</span><span class="p" data-group-id="0044749820-3">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="0044749820-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0044749820-4">[</span><span class="n">A</span><span class="p">|</span><span class="n">A</span><span class="p" data-group-id="0044749820-4">]</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0044749820-5">[</span><span class="mi">0</span><span class="p" data-group-id="0044749820-5">]</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0044749820-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">15</span><span class="p" data-group-id="0044749820-6">)</span><span class="p" data-group-id="0044749820-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="0044749820-7">{</span><span class="ss">data</span><span class="o">=</span><span class="n">Shared</span><span class="p" data-group-id="0044749820-7">}</span><span class="p">.</span></code></pre><p>In the process that calls <code class="inline">init2/0</code>, the size of the <code class="inline">data</code> field in the <code class="inline">state</code>
│ │ │  record will be 32 heap words. When the record is copied to the newly created
│ │ │  process, sharing will be lost and the size of the copied <code class="inline">data</code> field will be
│ │ │  131070 heap words. More details about
│ │ │  <a href="eff_guide_processes.html#loss-of-sharing">loss off sharing</a> are found in a later
│ │ │  section.</p><p>To avoid the problem, outside of the fun extract only the fields of the record
│ │ │ -that are actually used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental1</span><span class="p" data-group-id="4946266322-1">(</span><span class="n">State</span><span class="p" data-group-id="4946266322-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +that are actually used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental1</span><span class="p" data-group-id="9928108227-1">(</span><span class="n">State</span><span class="p" data-group-id="9928108227-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">info</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="4946266322-2">(</span><span class="nf">fun</span><span class="p" data-group-id="4946266322-3">(</span><span class="p" data-group-id="4946266322-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4946266322-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4946266322-5">[</span><span class="n">Info</span><span class="p" data-group-id="4946266322-5">]</span><span class="p" data-group-id="4946266322-4">)</span><span class="w">
│ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="4946266322-2">)</span><span class="p">.</span></code></pre><p>Similarly, outside of the fun extract only the map elements that are actually
│ │ │ -used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental2</span><span class="p" data-group-id="5787397624-1">(</span><span class="n">State</span><span class="p" data-group-id="5787397624-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">map_get</span><span class="p" data-group-id="5787397624-2">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="5787397624-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="5787397624-3">(</span><span class="nf">fun</span><span class="p" data-group-id="5787397624-4">(</span><span class="p" data-group-id="5787397624-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5787397624-5">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5787397624-6">[</span><span class="n">Info</span><span class="p" data-group-id="5787397624-6">]</span><span class="p" data-group-id="5787397624-5">)</span><span class="w">
│ │ │ -          </span><span class="k">end</span><span class="p" data-group-id="5787397624-3">)</span><span class="p">.</span></code></pre><h2 id="list_to_atom-1" class="section-heading">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="9928108227-2">(</span><span class="nf">fun</span><span class="p" data-group-id="9928108227-3">(</span><span class="p" data-group-id="9928108227-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9928108227-4">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9928108227-5">[</span><span class="n">Info</span><span class="p" data-group-id="9928108227-5">]</span><span class="p" data-group-id="9928108227-4">)</span><span class="w">
│ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="9928108227-2">)</span><span class="p">.</span></code></pre><p>Similarly, outside of the fun extract only the map elements that are actually
│ │ │ +used:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">fixed_accidental2</span><span class="p" data-group-id="3565178213-1">(</span><span class="n">State</span><span class="p" data-group-id="3565178213-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Info</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">map_get</span><span class="p" data-group-id="3565178213-2">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="3565178213-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="3565178213-3">(</span><span class="nf">fun</span><span class="p" data-group-id="3565178213-4">(</span><span class="p" data-group-id="3565178213-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3565178213-5">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="s">\n&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3565178213-6">[</span><span class="n">Info</span><span class="p" data-group-id="3565178213-6">]</span><span class="p" data-group-id="3565178213-5">)</span><span class="w">
│ │ │ +          </span><span class="k">end</span><span class="p" data-group-id="3565178213-3">)</span><span class="p">.</span></code></pre><h2 id="list_to_atom-1" class="section-heading">
│ │ │    <a href="#list_to_atom-1" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">list_to_atom/1</span>
│ │ │  </h2>
│ │ │  <p>Atoms are not garbage-collected. Once an atom is created, it is never removed.
│ │ │  The emulator terminates if the limit for the number of atoms (1,048,576 by
│ │ │  default) is reached.</p><p>Therefore, converting arbitrary input strings to atoms can be dangerous in a
│ │ │  system that runs continuously. If only certain well-defined atoms are allowed as
│ │ │  input, <a href="../../erts-15.2.7.3/doc/html/erlang.html#list_to_existing_atom/1"><code class="inline">list_to_existing_atom/1</code></a> or
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_existing_atom/1"><code class="inline">binary_to_existing_atom/1</code></a> can be used
│ │ │  to guard against a denial-of-service attack. (All atoms that are allowed must
│ │ │  have been created earlier, for example, by using all of them in a module
│ │ │  and loading that module.)</p><p>Using <a href="../../erts-15.2.7.3/doc/html/erlang.html#list_to_atom/1"><code class="inline">list_to_atom/1</code></a> to construct an atom that
│ │ │ -is passed to <a href="../../erts-15.2.7.3/doc/html/erlang.html#apply/3"><code class="inline">apply/3</code></a> is quite expensive.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">apply</span><span class="p" data-group-id="8840370967-1">(</span><span class="nf">list_to_atom</span><span class="p" data-group-id="8840370967-2">(</span><span class="s">&quot;some_prefix&quot;</span><span class="o">++</span><span class="n">Var</span><span class="p" data-group-id="8840370967-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="8840370967-1">)</span></code></pre><h2 id="length-1" class="section-heading">
│ │ │ +is passed to <a href="../../erts-15.2.7.3/doc/html/erlang.html#apply/3"><code class="inline">apply/3</code></a> is quite expensive.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">apply</span><span class="p" data-group-id="5161390889-1">(</span><span class="nf">list_to_atom</span><span class="p" data-group-id="5161390889-2">(</span><span class="s">&quot;some_prefix&quot;</span><span class="o">++</span><span class="n">Var</span><span class="p" data-group-id="5161390889-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="5161390889-1">)</span></code></pre><h2 id="length-1" class="section-heading">
│ │ │    <a href="#length-1" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">length/1</span>
│ │ │  </h2>
│ │ │  <p>The time for calculating the length of a list is proportional to the length of
│ │ │  the list, as opposed to <a href="../../erts-15.2.7.3/doc/html/erlang.html#tuple_size/1"><code class="inline">tuple_size/1</code></a>,
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#byte_size/1"><code class="inline">byte_size/1</code></a>, and <a href="../../erts-15.2.7.3/doc/html/erlang.html#bit_size/1"><code class="inline">bit_size/1</code></a>, which all
│ │ │  execute in constant time.</p><p>Normally, there is no need to worry about the speed of <a href="../../erts-15.2.7.3/doc/html/erlang.html#length/1"><code class="inline">length/1</code></a>,
│ │ │  because it is efficiently implemented in C. In time-critical code, you might
│ │ │  want to avoid it if the input list could potentially be very long.</p><p>Some uses of <a href="../../erts-15.2.7.3/doc/html/erlang.html#length/1"><code class="inline">length/1</code></a> can be replaced by matching. For example,
│ │ │ -the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="6451360000-1">(</span><span class="n">L</span><span class="p" data-group-id="6451360000-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="6451360000-2">(</span><span class="n">L</span><span class="p" data-group-id="6451360000-2">)</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="0864055315-1">(</span><span class="p" data-group-id="0864055315-2">[</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="0864055315-2">]</span><span class="o">=</span><span class="n">L</span><span class="p" data-group-id="0864055315-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="2807085457-1">(</span><span class="n">L</span><span class="p" data-group-id="2807085457-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="2807085457-2">(</span><span class="n">L</span><span class="p" data-group-id="2807085457-2">)</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="0089869450-1">(</span><span class="p" data-group-id="0089869450-2">[</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="0089869450-2">]</span><span class="o">=</span><span class="n">L</span><span class="p" data-group-id="0089869450-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>One slight difference is that <a href="../../erts-15.2.7.3/doc/html/erlang.html#length/1"><code class="inline">length(L)</code></a> fails if <code class="inline">L</code> is an
│ │ │  improper list, while the pattern in the second code fragment accepts an improper
│ │ │  list.</p><h2 id="setelement-3" class="section-heading">
│ │ │    <a href="#setelement-3" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">setelement/3</span>
│ │ │ @@ -238,18 +238,18 @@
│ │ │  <p><a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> copies the tuple it modifies. Therefore,
│ │ │  updating a tuple in a loop using <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> creates a new
│ │ │  copy of the tuple every time.</p><p>There is one exception to the rule that the tuple is copied. If the compiler
│ │ │  clearly can see that destructively updating the tuple would give the same result
│ │ │  as if the tuple was copied, the call to <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> is
│ │ │  replaced with a special destructive <code class="inline">setelement</code> instruction. In the following
│ │ │  code sequence, the first <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> call copies the tuple
│ │ │ -and modifies the ninth element:</p><pre><code class="makeup erlang" translate="no"><span class="nf">multiple_setelement</span><span class="p" data-group-id="2416571032-1">(</span><span class="n">T0</span><span class="p" data-group-id="2416571032-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="2416571032-2">(</span><span class="n">T0</span><span class="p" data-group-id="2416571032-2">)</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">9</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">T1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="2416571032-3">(</span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p" data-group-id="2416571032-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">T2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="2416571032-4">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="ss">foobar</span><span class="p" data-group-id="2416571032-4">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">setelement</span><span class="p" data-group-id="2416571032-5">(</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p">,</span><span class="w"> </span><span class="ss">new_value</span><span class="p" data-group-id="2416571032-5">)</span><span class="p">.</span></code></pre><p>The two following <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> calls modify the tuple in
│ │ │ +and modifies the ninth element:</p><pre><code class="makeup erlang" translate="no"><span class="nf">multiple_setelement</span><span class="p" data-group-id="3046232913-1">(</span><span class="n">T0</span><span class="p" data-group-id="3046232913-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="3046232913-2">(</span><span class="n">T0</span><span class="p" data-group-id="3046232913-2">)</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">9</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">T1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="3046232913-3">(</span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p" data-group-id="3046232913-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">T2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="3046232913-4">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="ss">foobar</span><span class="p" data-group-id="3046232913-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">setelement</span><span class="p" data-group-id="3046232913-5">(</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p">,</span><span class="w"> </span><span class="ss">new_value</span><span class="p" data-group-id="3046232913-5">)</span><span class="p">.</span></code></pre><p>The two following <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> calls modify the tuple in
│ │ │  place.</p><p>For the optimization to be applied, <em>all</em> the following conditions must be true:</p><ul><li>The tuple argument must be known to be a tuple of a known size.</li><li>The indices must be integer literals, not variables or expressions.</li><li>The indices must be given in descending order.</li><li>There must be no calls to another function in between the calls to
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a>.</li><li>The tuple returned from one <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a> call must only be
│ │ │  used in the subsequent call to <a href="../../erts-15.2.7.3/doc/html/erlang.html#setelement/3"><code class="inline">setelement/3</code></a>.</li></ul><p>If the code cannot be structured as in the <code class="inline">multiple_setelement/1</code> example, the
│ │ │  best way to modify multiple elements in a large tuple is to convert the tuple to
│ │ │  a list, modify the list, and convert it back to a tuple.</p><h2 id="size-1" class="section-heading">
│ │ │    <a href="#size-1" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/conc_prog.html
│ │ │ @@ -132,107 +132,107 @@
│ │ │  threads of execution in an Erlang program and to allow these threads to
│ │ │  communicate with each other. In Erlang, each thread of execution is called a
│ │ │  <em>process</em>.</p><p>(Aside: the term &quot;process&quot; is usually used when the threads of execution share
│ │ │  no data with each other and the term &quot;thread&quot; when they share data in some way.
│ │ │  Threads of execution in Erlang share no data, that is why they are called
│ │ │  processes).</p><p>The Erlang BIF <code class="inline">spawn</code> is used to create a new process:
│ │ │  <code class="inline">spawn(Module, Exported_Function, List of Arguments)</code>. Consider the following
│ │ │ -module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7943383232-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="7943383232-1">)</span><span class="p">.</span><span class="w">
│ │ │ +module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7090863148-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="7090863148-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7943383232-2">(</span><span class="p" data-group-id="7943383232-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7943383232-3">]</span><span class="p" data-group-id="7943383232-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7090863148-2">(</span><span class="p" data-group-id="7090863148-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7090863148-3">]</span><span class="p" data-group-id="7090863148-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">say_something</span><span class="p" data-group-id="7943383232-4">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7943383232-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">say_something</span><span class="p" data-group-id="7090863148-4">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7090863148-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">done</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">say_something</span><span class="p" data-group-id="7943383232-5">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="p" data-group-id="7943383232-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7943383232-6">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7943383232-7">[</span><span class="n">What</span><span class="p" data-group-id="7943383232-7">]</span><span class="p" data-group-id="7943383232-6">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">say_something</span><span class="p" data-group-id="7943383232-8">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7943383232-8">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="7943383232-9">(</span><span class="p" data-group-id="7943383232-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="7943383232-10">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7943383232-11">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7943383232-11">]</span><span class="p" data-group-id="7943383232-10">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="7943383232-12">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7943383232-13">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7943383232-13">]</span><span class="p" data-group-id="7943383232-12">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="7646024133-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="7646024133-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7646024133-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut14</span><span class="p" data-group-id="7646024133-2">}</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">say_something</span><span class="p" data-group-id="7646024133-3">(</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7646024133-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">say_something</span><span class="p" data-group-id="7090863148-5">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="p" data-group-id="7090863148-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7090863148-6">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7090863148-7">[</span><span class="n">What</span><span class="p" data-group-id="7090863148-7">]</span><span class="p" data-group-id="7090863148-6">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">say_something</span><span class="p" data-group-id="7090863148-8">(</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="n">Times</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7090863148-8">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="7090863148-9">(</span><span class="p" data-group-id="7090863148-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7090863148-10">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7090863148-11">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7090863148-11">]</span><span class="p" data-group-id="7090863148-10">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="7090863148-12">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7090863148-13">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7090863148-13">]</span><span class="p" data-group-id="7090863148-12">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="4593012454-1">(</span><span class="ss">tut14</span><span class="p" data-group-id="4593012454-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4593012454-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut14</span><span class="p" data-group-id="4593012454-2">}</span><span class="gp unselectable">
│ │ │ +6&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">say_something</span><span class="p" data-group-id="4593012454-3">(</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="4593012454-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │  </span><span class="ss">done</span></code></pre><p>As shown, the function <code class="inline">say_something</code> writes its first argument the number of
│ │ │  times specified by second argument. The function <code class="inline">start</code> starts two Erlang
│ │ │  processes, one that writes &quot;hello&quot; three times and one that writes &quot;goodbye&quot;
│ │ │  three times. Both processes use the function <code class="inline">say_something</code>. Notice that a
│ │ │  function used in this way by <code class="inline">spawn</code>, to start a process, must be exported from
│ │ │ -the module (that is, in the <code class="inline">-export</code> at the start of the module).</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9769579169-1">(</span><span class="p" data-group-id="9769579169-1">)</span><span class="p">.</span><span class="w">
│ │ │ +the module (that is, in the <code class="inline">-export</code> at the start of the module).</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nc">tut14</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9087521737-1">(</span><span class="p" data-group-id="9087521737-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │  </span><span class="ss">goodbye</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.63</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │  </span><span class="ss">goodbye</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="w">
│ │ │  </span><span class="ss">goodbye</span></code></pre><p>Notice that it did not write &quot;hello&quot; three times and then &quot;goodbye&quot; three times.
│ │ │  Instead, the first process wrote a &quot;hello&quot;, the second a &quot;goodbye&quot;, the first
│ │ │  another &quot;hello&quot; and so forth. But where did the <code class="inline">&lt;0.63.0&gt;</code> come from? The return
│ │ │  value of a function is the return value of the last &quot;thing&quot; in the function. The
│ │ │ -last thing in the function <code class="inline">start</code> is</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="1909115159-1">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1909115159-2">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1909115159-2">]</span><span class="p" data-group-id="1909115159-1">)</span><span class="p">.</span></code></pre><p><code class="inline">spawn</code> returns a <em>process identifier</em>, or <em>pid</em>, which uniquely identifies the
│ │ │ +last thing in the function <code class="inline">start</code> is</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="8066102853-1">(</span><span class="ss">tut14</span><span class="p">,</span><span class="w"> </span><span class="ss">say_something</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8066102853-2">[</span><span class="ss">goodbye</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="8066102853-2">]</span><span class="p" data-group-id="8066102853-1">)</span><span class="p">.</span></code></pre><p><code class="inline">spawn</code> returns a <em>process identifier</em>, or <em>pid</em>, which uniquely identifies the
│ │ │  process. So <code class="inline">&lt;0.63.0&gt;</code> is the pid of the <code class="inline">spawn</code> function call above. The next
│ │ │  example shows how to use pids.</p><p>Notice also that ~p is used instead of ~w in <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a>. To quote <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#tilde_p">the manual</a>:</p><blockquote><p>~p Writes the data with standard syntax in the same way as ~w, but breaks terms
│ │ │  whose printed representation is longer than one line into many lines and indents
│ │ │  each line sensibly. It also tries to detect flat lists of printable characters and
│ │ │  to output these as strings</p></blockquote><h2 id="message-passing" class="section-heading">
│ │ │    <a href="#message-passing" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Message Passing</span>
│ │ │  </h2>
│ │ │  <p>In the following example two processes are created and they send messages to
│ │ │ -each other a number of times.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8546228823-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="8546228823-1">)</span><span class="p">.</span><span class="w">
│ │ │ +each other a number of times.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4619417354-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="4619417354-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8546228823-2">(</span><span class="p" data-group-id="8546228823-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8546228823-3">]</span><span class="p" data-group-id="8546228823-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4619417354-2">(</span><span class="p" data-group-id="4619417354-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="4619417354-3">]</span><span class="p" data-group-id="4619417354-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="8546228823-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8546228823-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="4619417354-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4619417354-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8546228823-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8546228823-6">[</span><span class="p" data-group-id="8546228823-6">]</span><span class="p" data-group-id="8546228823-5">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4619417354-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4619417354-6">[</span><span class="p" data-group-id="4619417354-6">]</span><span class="p" data-group-id="4619417354-5">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="8546228823-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8546228823-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8546228823-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8546228823-9">(</span><span class="p" data-group-id="8546228823-9">)</span><span class="p" data-group-id="8546228823-8">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="4619417354-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4619417354-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4619417354-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4619417354-9">(</span><span class="p" data-group-id="4619417354-9">)</span><span class="p" data-group-id="4619417354-8">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8546228823-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8546228823-11">[</span><span class="p" data-group-id="8546228823-11">]</span><span class="p" data-group-id="8546228823-10">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4619417354-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4619417354-11">[</span><span class="p" data-group-id="4619417354-11">]</span><span class="p" data-group-id="4619417354-10">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="8546228823-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8546228823-12">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="4619417354-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4619417354-12">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="8546228823-13">(</span><span class="p" data-group-id="8546228823-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="4619417354-13">(</span><span class="p" data-group-id="4619417354-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8546228823-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8546228823-15">[</span><span class="p" data-group-id="8546228823-15">]</span><span class="p" data-group-id="8546228823-14">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8546228823-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="8546228823-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8546228823-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8546228823-18">[</span><span class="p" data-group-id="8546228823-18">]</span><span class="p" data-group-id="8546228823-17">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4619417354-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4619417354-15">[</span><span class="p" data-group-id="4619417354-15">]</span><span class="p" data-group-id="4619417354-14">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="4619417354-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="4619417354-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4619417354-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4619417354-18">[</span><span class="p" data-group-id="4619417354-18">]</span><span class="p" data-group-id="4619417354-17">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="8546228823-19">(</span><span class="p" data-group-id="8546228823-19">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="4619417354-19">(</span><span class="p" data-group-id="4619417354-19">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="8546228823-20">(</span><span class="p" data-group-id="8546228823-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="8546228823-21">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8546228823-22">[</span><span class="p" data-group-id="8546228823-22">]</span><span class="p" data-group-id="8546228823-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="8546228823-23">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8546228823-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="8546228823-24">]</span><span class="p" data-group-id="8546228823-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">c</span><span class="p" data-group-id="0339014192-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="0339014192-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0339014192-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut15</span><span class="p" data-group-id="0339014192-2">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">tut15</span><span class="p">:</span><span class="w"> </span><span class="nf">start</span><span class="p" data-group-id="0339014192-3">(</span><span class="p" data-group-id="0339014192-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="4619417354-20">(</span><span class="p" data-group-id="4619417354-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="4619417354-21">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4619417354-22">[</span><span class="p" data-group-id="4619417354-22">]</span><span class="p" data-group-id="4619417354-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="4619417354-23">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4619417354-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4619417354-24">]</span><span class="p" data-group-id="4619417354-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">c</span><span class="p" data-group-id="3427917566-1">(</span><span class="ss">tut15</span><span class="p" data-group-id="3427917566-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3427917566-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut15</span><span class="p" data-group-id="3427917566-2">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">tut15</span><span class="p">:</span><span class="w"> </span><span class="nf">start</span><span class="p" data-group-id="3427917566-3">(</span><span class="p" data-group-id="3427917566-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.36</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="ss">ping</span><span class="w"> </span><span class="ss">finished</span><span class="w">
│ │ │ -</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>The function <code class="inline">start</code> first creates a process, let us call it &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="9171789625-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9171789625-2">[</span><span class="p" data-group-id="9171789625-2">]</span><span class="p" data-group-id="9171789625-1">)</span></code></pre><p>This process executes <code class="inline">tut15:pong()</code>. <code class="inline">Pong_PID</code> is the process identity of the
│ │ │ -&quot;pong&quot; process. The function <code class="inline">start</code> now creates another process &quot;ping&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="2249854097-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2249854097-2">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="2249854097-2">]</span><span class="p" data-group-id="2249854097-1">)</span><span class="p">,</span></code></pre><p>This process executes:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="6691850041-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="6691850041-1">)</span></code></pre><p><code class="inline">&lt;0.36.0&gt;</code> is the return value from the <code class="inline">start</code> function.</p><p>The process &quot;pong&quot; now does:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ +</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>The function <code class="inline">start</code> first creates a process, let us call it &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="5874507543-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5874507543-2">[</span><span class="p" data-group-id="5874507543-2">]</span><span class="p" data-group-id="5874507543-1">)</span></code></pre><p>This process executes <code class="inline">tut15:pong()</code>. <code class="inline">Pong_PID</code> is the process identity of the
│ │ │ +&quot;pong&quot; process. The function <code class="inline">start</code> now creates another process &quot;ping&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="1757308234-1">(</span><span class="ss">tut15</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1757308234-2">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="1757308234-2">]</span><span class="p" data-group-id="1757308234-1">)</span><span class="p">,</span></code></pre><p>This process executes:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="3047444201-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="3047444201-1">)</span></code></pre><p><code class="inline">&lt;0.36.0&gt;</code> is the return value from the <code class="inline">start</code> function.</p><p>The process &quot;pong&quot; now does:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │      </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4979147594-1">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4979147594-2">[</span><span class="p" data-group-id="4979147594-2">]</span><span class="p" data-group-id="4979147594-1">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4979147594-3">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="4979147594-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4979147594-4">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4979147594-5">[</span><span class="p" data-group-id="4979147594-5">]</span><span class="p" data-group-id="4979147594-4">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0968348577-1">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0968348577-2">[</span><span class="p" data-group-id="0968348577-2">]</span><span class="p" data-group-id="0968348577-1">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0968348577-3">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="0968348577-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0968348577-4">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0968348577-5">[</span><span class="p" data-group-id="0968348577-5">]</span><span class="p" data-group-id="0968348577-4">)</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="nf">pong</span><span class="p" data-group-id="4979147594-6">(</span><span class="p" data-group-id="4979147594-6">)</span><span class="w">
│ │ │ +        </span><span class="nf">pong</span><span class="p" data-group-id="0968348577-6">(</span><span class="p" data-group-id="0968348577-6">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">receive</code> construct is used to allow processes to wait for messages from
│ │ │  other processes. It has the following format:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │     </span><span class="ss">pattern1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │         </span><span class="ss">actions1</span><span class="p">;</span><span class="w">
│ │ │     </span><span class="ss">pattern2</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │         </span><span class="ss">actions2</span><span class="p">;</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ @@ -253,84 +253,84 @@
│ │ │  queue (keeping the first message and any other messages in the queue). If the
│ │ │  second message does not match, the third message is tried, and so on, until the
│ │ │  end of the queue is reached. If the end of the queue is reached, the process
│ │ │  blocks (stops execution) and waits until a new message is received and this
│ │ │  procedure is repeated.</p><p>The Erlang implementation is &quot;clever&quot; and minimizes the number of times each
│ │ │  message is tested against the patterns in each <code class="inline">receive</code>.</p><p>Now back to the ping pong example.</p><p>&quot;Pong&quot; is waiting for messages. If the atom <code class="inline">finished</code> is received, &quot;pong&quot;
│ │ │  writes &quot;Pong finished&quot; to the output and, as it has nothing more to do,
│ │ │ -terminates. If it receives a message with the format:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4412779629-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="4412779629-1">}</span></code></pre><p>it writes &quot;Pong received ping&quot; to the output and sends the atom <code class="inline">pong</code> to the
│ │ │ +terminates. If it receives a message with the format:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0951062273-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="0951062273-1">}</span></code></pre><p>it writes &quot;Pong received ping&quot; to the output and sends the atom <code class="inline">pong</code> to the
│ │ │  process &quot;ping&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span></code></pre><p>Notice how the operator &quot;!&quot; is used to send messages. The syntax of &quot;!&quot; is:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Message</span></code></pre><p>That is, <code class="inline">Message</code> (any Erlang term) is sent to the process with identity <code class="inline">Pid</code>.</p><p>After sending the message <code class="inline">pong</code> to the process &quot;ping&quot;, &quot;pong&quot; calls the <code class="inline">pong</code>
│ │ │  function again, which causes it to get back to the <code class="inline">receive</code> again and wait for
│ │ │ -another message.</p><p>Now let us look at the process &quot;ping&quot;. Recall that it was started by executing:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="4058553639-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="4058553639-1">)</span></code></pre><p>Looking at the function <code class="inline">ping/2</code>, the second clause of <code class="inline">ping/2</code> is executed
│ │ │ +another message.</p><p>Now let us look at the process &quot;ping&quot;. Recall that it was started by executing:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut15</span><span class="p">:</span><span class="nf">ping</span><span class="p" data-group-id="6160263305-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="6160263305-1">)</span></code></pre><p>Looking at the function <code class="inline">ping/2</code>, the second clause of <code class="inline">ping/2</code> is executed
│ │ │  since the value of the first argument is 3 (not 0) (first clause head is
│ │ │ -<code class="inline">ping(0,Pong_PID)</code>, second clause head is <code class="inline">ping(N,Pong_PID)</code>, so <code class="inline">N</code> becomes 3).</p><p>The second clause sends a message to &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2666101874-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2666101874-2">(</span><span class="p" data-group-id="2666101874-2">)</span><span class="p" data-group-id="2666101874-1">}</span><span class="p">,</span></code></pre><p><a href="../../erts-15.2.7.3/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a> returns the pid of the process that executes <a href="../../erts-15.2.7.3/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a>, in this case the
│ │ │ +<code class="inline">ping(0,Pong_PID)</code>, second clause head is <code class="inline">ping(N,Pong_PID)</code>, so <code class="inline">N</code> becomes 3).</p><p>The second clause sends a message to &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3545165006-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3545165006-2">(</span><span class="p" data-group-id="3545165006-2">)</span><span class="p" data-group-id="3545165006-1">}</span><span class="p">,</span></code></pre><p><a href="../../erts-15.2.7.3/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a> returns the pid of the process that executes <a href="../../erts-15.2.7.3/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a>, in this case the
│ │ │  pid of &quot;ping&quot;. (Recall the code for &quot;pong&quot;, this lands up in the variable
│ │ │  <code class="inline">Ping_PID</code> in the <code class="inline">receive</code> previously explained.)</p><p>&quot;Ping&quot; now waits for a reply from &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │      </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0483307284-1">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0483307284-2">[</span><span class="p" data-group-id="0483307284-2">]</span><span class="p" data-group-id="0483307284-1">)</span><span class="w">
│ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9596053065-1">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9596053065-2">[</span><span class="p" data-group-id="9596053065-2">]</span><span class="p" data-group-id="9596053065-1">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">,</span></code></pre><p>It writes &quot;Ping received pong&quot; when this reply arrives, after which &quot;ping&quot; calls
│ │ │ -the <code class="inline">ping</code> function again.</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="6917887518-1">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="6917887518-1">)</span></code></pre><p><code class="inline">N-1</code> causes the first argument to be decremented until it becomes 0. When this
│ │ │ -occurs, the first clause of <code class="inline">ping/2</code> is executed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="7261861114-1">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="7261861114-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +the <code class="inline">ping</code> function again.</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="2620989795-1">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="2620989795-1">)</span></code></pre><p><code class="inline">N-1</code> causes the first argument to be decremented until it becomes 0. When this
│ │ │ +occurs, the first clause of <code class="inline">ping/2</code> is executed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">ping</span><span class="p" data-group-id="2666881680-1">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_PID</span><span class="p" data-group-id="2666881680-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Pong_PID</span><span class="w"> </span><span class="o">!</span><span class="w">  </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7261861114-2">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7261861114-3">[</span><span class="p" data-group-id="7261861114-3">]</span><span class="p" data-group-id="7261861114-2">)</span><span class="p">;</span></code></pre><p>The atom <code class="inline">finished</code> is sent to &quot;pong&quot; (causing it to terminate as described
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2666881680-2">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2666881680-3">[</span><span class="p" data-group-id="2666881680-3">]</span><span class="p" data-group-id="2666881680-2">)</span><span class="p">;</span></code></pre><p>The atom <code class="inline">finished</code> is sent to &quot;pong&quot; (causing it to terminate as described
│ │ │  above) and &quot;ping finished&quot; is written to the output. &quot;Ping&quot; then terminates as
│ │ │  it has nothing left to do.</p><h2 id="registered-process-names" class="section-heading">
│ │ │    <a href="#registered-process-names" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Registered Process Names</span>
│ │ │  </h2>
│ │ │  <p>In the above example, &quot;pong&quot; was first created to be able to give the identity
│ │ │  of &quot;pong&quot; when &quot;ping&quot; was started. That is, in some way &quot;ping&quot; must be able to
│ │ │  know the identity of &quot;pong&quot; to be able to send a message to it. Sometimes
│ │ │  processes which need to know each other's identities are started independently
│ │ │  of each other. Erlang thus provides a mechanism for processes to be given names
│ │ │  so that these names can be used as identities instead of pids. This is done by
│ │ │ -using the <code class="inline">register</code> BIF:</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="3620657246-1">(</span><span class="ss">some_atom</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="3620657246-1">)</span></code></pre><p>Let us now rewrite the ping pong example using this and give the name <code class="inline">pong</code> to
│ │ │ -the &quot;pong&quot; process:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8223769819-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="8223769819-1">)</span><span class="p">.</span><span class="w">
│ │ │ +using the <code class="inline">register</code> BIF:</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="0859693869-1">(</span><span class="ss">some_atom</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="0859693869-1">)</span></code></pre><p>Let us now rewrite the ping pong example using this and give the name <code class="inline">pong</code> to
│ │ │ +the &quot;pong&quot; process:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1162920738-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="1162920738-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8223769819-2">(</span><span class="p" data-group-id="8223769819-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8223769819-3">]</span><span class="p" data-group-id="8223769819-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1162920738-2">(</span><span class="p" data-group-id="1162920738-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1162920738-3">]</span><span class="p" data-group-id="1162920738-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="8223769819-4">(</span><span class="mi">0</span><span class="p" data-group-id="8223769819-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="1162920738-4">(</span><span class="mi">0</span><span class="p" data-group-id="1162920738-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8223769819-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8223769819-6">[</span><span class="p" data-group-id="8223769819-6">]</span><span class="p" data-group-id="8223769819-5">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1162920738-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1162920738-6">[</span><span class="p" data-group-id="1162920738-6">]</span><span class="p" data-group-id="1162920738-5">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="8223769819-7">(</span><span class="n">N</span><span class="p" data-group-id="8223769819-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8223769819-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8223769819-9">(</span><span class="p" data-group-id="8223769819-9">)</span><span class="p" data-group-id="8223769819-8">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="1162920738-7">(</span><span class="n">N</span><span class="p" data-group-id="1162920738-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1162920738-8">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1162920738-9">(</span><span class="p" data-group-id="1162920738-9">)</span><span class="p" data-group-id="1162920738-8">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8223769819-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8223769819-11">[</span><span class="p" data-group-id="8223769819-11">]</span><span class="p" data-group-id="8223769819-10">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1162920738-10">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1162920738-11">[</span><span class="p" data-group-id="1162920738-11">]</span><span class="p" data-group-id="1162920738-10">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="8223769819-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="8223769819-12">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="1162920738-12">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="1162920738-12">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="8223769819-13">(</span><span class="p" data-group-id="8223769819-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="1162920738-13">(</span><span class="p" data-group-id="1162920738-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8223769819-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8223769819-15">[</span><span class="p" data-group-id="8223769819-15">]</span><span class="p" data-group-id="8223769819-14">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8223769819-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="8223769819-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8223769819-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8223769819-18">[</span><span class="p" data-group-id="8223769819-18">]</span><span class="p" data-group-id="8223769819-17">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1162920738-14">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1162920738-15">[</span><span class="p" data-group-id="1162920738-15">]</span><span class="p" data-group-id="1162920738-14">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1162920738-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="1162920738-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1162920738-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1162920738-18">[</span><span class="p" data-group-id="1162920738-18">]</span><span class="p" data-group-id="1162920738-17">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="8223769819-19">(</span><span class="p" data-group-id="8223769819-19">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="1162920738-19">(</span><span class="p" data-group-id="1162920738-19">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="8223769819-20">(</span><span class="p" data-group-id="8223769819-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="8223769819-21">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="8223769819-22">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8223769819-23">[</span><span class="p" data-group-id="8223769819-23">]</span><span class="p" data-group-id="8223769819-22">)</span><span class="p" data-group-id="8223769819-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="8223769819-24">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8223769819-25">[</span><span class="mi">3</span><span class="p" data-group-id="8223769819-25">]</span><span class="p" data-group-id="8223769819-24">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nf">c</span><span class="p" data-group-id="4805750738-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="4805750738-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4805750738-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut16</span><span class="p" data-group-id="4805750738-2">}</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">tut16</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4805750738-3">(</span><span class="p" data-group-id="4805750738-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1162920738-20">(</span><span class="p" data-group-id="1162920738-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="1162920738-21">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1162920738-22">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1162920738-23">[</span><span class="p" data-group-id="1162920738-23">]</span><span class="p" data-group-id="1162920738-22">)</span><span class="p" data-group-id="1162920738-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1162920738-24">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1162920738-25">[</span><span class="mi">3</span><span class="p" data-group-id="1162920738-25">]</span><span class="p" data-group-id="1162920738-24">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nf">c</span><span class="p" data-group-id="0273233965-1">(</span><span class="ss">tut16</span><span class="p" data-group-id="0273233965-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0273233965-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut16</span><span class="p" data-group-id="0273233965-2">}</span><span class="gp unselectable">
│ │ │ +3&gt; </span><span class="nc">tut16</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="0273233965-3">(</span><span class="p" data-group-id="0273233965-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.38</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="ss">ping</span><span class="w"> </span><span class="ss">finished</span><span class="w">
│ │ │ -</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>Here the <code class="inline">start/0</code> function,</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="3944081088-1">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="3944081088-2">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3944081088-3">[</span><span class="p" data-group-id="3944081088-3">]</span><span class="p" data-group-id="3944081088-2">)</span><span class="p" data-group-id="3944081088-1">)</span><span class="p">,</span></code></pre><p>both spawns the &quot;pong&quot; process and gives it the name <code class="inline">pong</code>. In the &quot;ping&quot;
│ │ │ -process, messages can be sent to <code class="inline">pong</code> by:</p><pre><code class="makeup erlang" translate="no"><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6558747407-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6558747407-2">(</span><span class="p" data-group-id="6558747407-2">)</span><span class="p" data-group-id="6558747407-1">}</span><span class="p">,</span></code></pre><p><code class="inline">ping/2</code> now becomes <code class="inline">ping/1</code> as the argument <code class="inline">Pong_PID</code> is not needed.</p><h2 id="distributed-programming" class="section-heading">
│ │ │ +</span><span class="n">Pong</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>Here the <code class="inline">start/0</code> function,</p><pre><code class="makeup erlang" translate="no"><span class="nf">register</span><span class="p" data-group-id="7120235513-1">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="7120235513-2">(</span><span class="ss">tut16</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7120235513-3">[</span><span class="p" data-group-id="7120235513-3">]</span><span class="p" data-group-id="7120235513-2">)</span><span class="p" data-group-id="7120235513-1">)</span><span class="p">,</span></code></pre><p>both spawns the &quot;pong&quot; process and gives it the name <code class="inline">pong</code>. In the &quot;ping&quot;
│ │ │ +process, messages can be sent to <code class="inline">pong</code> by:</p><pre><code class="makeup erlang" translate="no"><span class="ss">pong</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5159387474-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5159387474-2">(</span><span class="p" data-group-id="5159387474-2">)</span><span class="p" data-group-id="5159387474-1">}</span><span class="p">,</span></code></pre><p><code class="inline">ping/2</code> now becomes <code class="inline">ping/1</code> as the argument <code class="inline">Pong_PID</code> is not needed.</p><h2 id="distributed-programming" class="section-heading">
│ │ │    <a href="#distributed-programming" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Distributed Programming</span>
│ │ │  </h2>
│ │ │  <p>Let us rewrite the ping pong program with &quot;ping&quot; and &quot;pong&quot; on different
│ │ │  computers. First a few things are needed to set up to get this to work. The
│ │ │ @@ -350,106 +350,106 @@
│ │ │  of the file. This is a requirement.</p><p>When you start an Erlang system that is going to talk to other Erlang systems,
│ │ │  you must give it a name, for example:</p><pre><code class="text">$ erl -sname my_name</code></pre><p>We will see more details of this later. If you want to experiment with
│ │ │  distributed Erlang, but you only have one computer to work on, you can start two
│ │ │  separate Erlang systems on the same computer but give them different names. Each
│ │ │  Erlang system running on a computer is called an <em>Erlang node</em>.</p><p>(Note: <code class="inline">erl -sname</code> assumes that all nodes are in the same IP domain and we can
│ │ │  use only the first component of the IP address, if we want to use nodes in
│ │ │  different domains we use <code class="inline">-name</code> instead, but then all IP address must be given
│ │ │ -in full.)</p><p>Here is the ping pong example modified to run on two separate nodes:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2022284420-1">(</span><span class="ss">tut17</span><span class="p" data-group-id="2022284420-1">)</span><span class="p">.</span><span class="w">
│ │ │ +in full.)</p><p>Here is the ping pong example modified to run on two separate nodes:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6381936331-1">(</span><span class="ss">tut17</span><span class="p" data-group-id="6381936331-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2022284420-2">(</span><span class="p" data-group-id="2022284420-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2022284420-3">]</span><span class="p" data-group-id="2022284420-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6381936331-2">(</span><span class="p" data-group-id="6381936331-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6381936331-3">]</span><span class="p" data-group-id="6381936331-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="2022284420-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2022284420-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2022284420-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2022284420-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2022284420-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2022284420-7">[</span><span class="p" data-group-id="2022284420-7">]</span><span class="p" data-group-id="2022284420-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="6381936331-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="6381936331-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6381936331-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="6381936331-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6381936331-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6381936331-7">[</span><span class="p" data-group-id="6381936331-7">]</span><span class="p" data-group-id="6381936331-6">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="2022284420-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2022284420-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2022284420-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2022284420-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2022284420-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2022284420-11">(</span><span class="p" data-group-id="2022284420-11">)</span><span class="p" data-group-id="2022284420-10">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="6381936331-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="6381936331-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6381936331-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="6381936331-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6381936331-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6381936331-11">(</span><span class="p" data-group-id="6381936331-11">)</span><span class="p" data-group-id="6381936331-10">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2022284420-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2022284420-13">[</span><span class="p" data-group-id="2022284420-13">]</span><span class="p" data-group-id="2022284420-12">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6381936331-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6381936331-13">[</span><span class="p" data-group-id="6381936331-13">]</span><span class="p" data-group-id="6381936331-12">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="2022284420-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2022284420-14">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="6381936331-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="6381936331-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="2022284420-15">(</span><span class="p" data-group-id="2022284420-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="6381936331-15">(</span><span class="p" data-group-id="6381936331-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2022284420-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2022284420-17">[</span><span class="p" data-group-id="2022284420-17">]</span><span class="p" data-group-id="2022284420-16">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="2022284420-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="2022284420-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2022284420-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2022284420-20">[</span><span class="p" data-group-id="2022284420-20">]</span><span class="p" data-group-id="2022284420-19">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6381936331-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6381936331-17">[</span><span class="p" data-group-id="6381936331-17">]</span><span class="p" data-group-id="6381936331-16">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="6381936331-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="6381936331-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6381936331-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6381936331-20">[</span><span class="p" data-group-id="6381936331-20">]</span><span class="p" data-group-id="6381936331-19">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="2022284420-21">(</span><span class="p" data-group-id="2022284420-21">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="6381936331-21">(</span><span class="p" data-group-id="6381936331-21">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_pong</span><span class="p" data-group-id="2022284420-22">(</span><span class="p" data-group-id="2022284420-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="2022284420-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="2022284420-24">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2022284420-25">[</span><span class="p" data-group-id="2022284420-25">]</span><span class="p" data-group-id="2022284420-24">)</span><span class="p" data-group-id="2022284420-23">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_pong</span><span class="p" data-group-id="6381936331-22">(</span><span class="p" data-group-id="6381936331-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="6381936331-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="6381936331-24">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6381936331-25">[</span><span class="p" data-group-id="6381936331-25">]</span><span class="p" data-group-id="6381936331-24">)</span><span class="p" data-group-id="6381936331-23">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_ping</span><span class="p" data-group-id="2022284420-26">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="2022284420-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="2022284420-27">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2022284420-28">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="2022284420-28">]</span><span class="p" data-group-id="2022284420-27">)</span><span class="p">.</span></code></pre><p>Let us assume there are two computers called gollum and kosken. First a node is
│ │ │ +</span><span class="nf">start_ping</span><span class="p" data-group-id="6381936331-26">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="6381936331-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="6381936331-27">(</span><span class="ss">tut17</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6381936331-28">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="6381936331-28">]</span><span class="p" data-group-id="6381936331-27">)</span><span class="p">.</span></code></pre><p>Let us assume there are two computers called gollum and kosken. First a node is
│ │ │  started on kosken, called ping, and then a node on gollum, called pong.</p><p>On kosken (on a Linux/UNIX system):</p><pre><code class="text">kosken&gt; erl -sname ping
│ │ │  Erlang (BEAM) emulator version 5.2.3.7 [hipe] [threads:0]
│ │ │  
│ │ │  Eshell V5.2.3.7  (abort with ^G)
│ │ │  (ping@kosken)1&gt;</code></pre><p>On gollum:</p><pre><code class="text">gollum&gt; erl -sname pong
│ │ │  Erlang (BEAM) emulator version 5.2.3.7 [hipe] [threads:0]
│ │ │  
│ │ │  Eshell V5.2.3.7  (abort with ^G)
│ │ │ -(pong@gollum)1&gt;</code></pre><p>Now the &quot;pong&quot; process on gollum is started:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_pong</span><span class="p" data-group-id="7573174772-1">(</span><span class="p" data-group-id="7573174772-1">)</span><span class="p">.</span><span class="w">
│ │ │ +(pong@gollum)1&gt;</code></pre><p>Now the &quot;pong&quot; process on gollum is started:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_pong</span><span class="p" data-group-id="6115016399-1">(</span><span class="p" data-group-id="6115016399-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><p>And the &quot;ping&quot; process on kosken is started (from the code above you can see
│ │ │  that a parameter of the <code class="inline">start_ping</code> function is the node name of the Erlang
│ │ │ -system where &quot;pong&quot; is running):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(ping@kosken)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_ping</span><span class="p" data-group-id="6742018988-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="6742018988-1">)</span><span class="p">.</span><span class="w">
│ │ │ +system where &quot;pong&quot; is running):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(ping@kosken)1&gt; </span><span class="nc">tut17</span><span class="p">:</span><span class="nf">start_ping</span><span class="p" data-group-id="0333494651-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="0333494651-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.37</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="ss">ping</span><span class="w"> </span><span class="ss">finished</span></code></pre><p>As shown, the ping pong program has run. On the &quot;pong&quot; side:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)2&gt; </span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="nf">finished</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4644101847-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="4644101847-1">)</span><span class="mi">2</span><span class="o">&gt;</span><span class="w"> </span></code></pre><p>Looking at the <code class="inline">tut17</code> code, you see that the <code class="inline">pong</code> function itself is
│ │ │ +</span><span class="p" data-group-id="3473763506-1">(</span><span class="ss">pong@gollum</span><span class="p" data-group-id="3473763506-1">)</span><span class="mi">2</span><span class="o">&gt;</span><span class="w"> </span></code></pre><p>Looking at the <code class="inline">tut17</code> code, you see that the <code class="inline">pong</code> function itself is
│ │ │  unchanged, the following lines work in the same way irrespective of on which
│ │ │ -node the &quot;ping&quot; process is executes:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6931151084-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="6931151084-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6931151084-2">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6931151084-3">[</span><span class="p" data-group-id="6931151084-3">]</span><span class="p" data-group-id="6931151084-2">)</span><span class="p">,</span><span class="w">
│ │ │ +node the &quot;ping&quot; process is executes:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4199856672-1">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="4199856672-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4199856672-2">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4199856672-3">[</span><span class="p" data-group-id="4199856672-3">]</span><span class="p" data-group-id="4199856672-2">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span></code></pre><p>Thus, Erlang pids contain information about where the process executes. So if
│ │ │  you know the pid of a process, the <code class="inline">!</code> operator can be used to send it a
│ │ │ -message disregarding if the process is on the same node or on a different node.</p><p>A difference is how messages are sent to a registered process on another node:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1971847747-1">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1971847747-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1971847747-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1971847747-3">(</span><span class="p" data-group-id="1971847747-3">)</span><span class="p" data-group-id="1971847747-2">}</span><span class="p">,</span></code></pre><p>A tuple <code class="inline">{registered_name,node_name}</code> is used instead of just the
│ │ │ +message disregarding if the process is on the same node or on a different node.</p><p>A difference is how messages are sent to a registered process on another node:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0306773934-1">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="0306773934-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0306773934-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0306773934-3">(</span><span class="p" data-group-id="0306773934-3">)</span><span class="p" data-group-id="0306773934-2">}</span><span class="p">,</span></code></pre><p>A tuple <code class="inline">{registered_name,node_name}</code> is used instead of just the
│ │ │  <code class="inline">registered_name</code>.</p><p>In the previous example, &quot;ping&quot; and &quot;pong&quot; were started from the shells of two
│ │ │  separate Erlang nodes. <code class="inline">spawn</code> can also be used to start processes in other
│ │ │  nodes.</p><p>The next example is the ping pong program, yet again, but this time &quot;ping&quot; is
│ │ │ -started in another node:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3377235734-1">(</span><span class="ss">tut18</span><span class="p" data-group-id="3377235734-1">)</span><span class="p">.</span><span class="w">
│ │ │ +started in another node:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1512468236-1">(</span><span class="ss">tut18</span><span class="p" data-group-id="1512468236-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3377235734-2">(</span><span class="p" data-group-id="3377235734-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3377235734-3">]</span><span class="p" data-group-id="3377235734-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1512468236-2">(</span><span class="p" data-group-id="1512468236-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1512468236-3">]</span><span class="p" data-group-id="1512468236-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="3377235734-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3377235734-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3377235734-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3377235734-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3377235734-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3377235734-7">[</span><span class="p" data-group-id="3377235734-7">]</span><span class="p" data-group-id="3377235734-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="1512468236-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1512468236-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1512468236-5">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1512468236-5">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">finished</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1512468236-6">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512468236-7">[</span><span class="p" data-group-id="1512468236-7">]</span><span class="p" data-group-id="1512468236-6">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="3377235734-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3377235734-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3377235734-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3377235734-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3377235734-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3377235734-11">(</span><span class="p" data-group-id="3377235734-11">)</span><span class="p" data-group-id="3377235734-10">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="1512468236-8">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1512468236-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1512468236-9">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1512468236-9">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1512468236-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1512468236-11">(</span><span class="p" data-group-id="1512468236-11">)</span><span class="p" data-group-id="1512468236-10">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3377235734-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3377235734-13">[</span><span class="p" data-group-id="3377235734-13">]</span><span class="p" data-group-id="3377235734-12">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1512468236-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512468236-13">[</span><span class="p" data-group-id="1512468236-13">]</span><span class="p" data-group-id="1512468236-12">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="3377235734-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3377235734-14">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="1512468236-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1512468236-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="3377235734-15">(</span><span class="p" data-group-id="3377235734-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="1512468236-15">(</span><span class="p" data-group-id="1512468236-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">finished</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3377235734-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3377235734-17">[</span><span class="p" data-group-id="3377235734-17">]</span><span class="p" data-group-id="3377235734-16">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="3377235734-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="3377235734-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3377235734-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3377235734-20">[</span><span class="p" data-group-id="3377235734-20">]</span><span class="p" data-group-id="3377235734-19">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1512468236-16">(</span><span class="s">&quot;Pong finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512468236-17">[</span><span class="p" data-group-id="1512468236-17">]</span><span class="p" data-group-id="1512468236-16">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1512468236-18">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="1512468236-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1512468236-19">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512468236-20">[</span><span class="p" data-group-id="1512468236-20">]</span><span class="p" data-group-id="1512468236-19">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="3377235734-21">(</span><span class="p" data-group-id="3377235734-21">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="1512468236-21">(</span><span class="p" data-group-id="1512468236-21">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="3377235734-22">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="3377235734-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="3377235734-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="3377235734-24">(</span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3377235734-25">[</span><span class="p" data-group-id="3377235734-25">]</span><span class="p" data-group-id="3377235734-24">)</span><span class="p" data-group-id="3377235734-23">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="3377235734-26">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3377235734-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="3377235734-28">(</span><span class="p" data-group-id="3377235734-28">)</span><span class="p" data-group-id="3377235734-27">]</span><span class="p" data-group-id="3377235734-26">)</span><span class="p">.</span></code></pre><p>Assuming an Erlang system called ping (but not the &quot;ping&quot; process) has already
│ │ │ -been started on kosken, then on gollum this is done:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut18</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="0480647920-1">(</span><span class="ss">ping@kosken</span><span class="p" data-group-id="0480647920-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1512468236-22">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="1512468236-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="1512468236-23">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1512468236-24">(</span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512468236-25">[</span><span class="p" data-group-id="1512468236-25">]</span><span class="p" data-group-id="1512468236-24">)</span><span class="p" data-group-id="1512468236-23">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1512468236-26">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut18</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1512468236-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="1512468236-28">(</span><span class="p" data-group-id="1512468236-28">)</span><span class="p" data-group-id="1512468236-27">]</span><span class="p" data-group-id="1512468236-26">)</span><span class="p">.</span></code></pre><p>Assuming an Erlang system called ping (but not the &quot;ping&quot; process) has already
│ │ │ +been started on kosken, then on gollum this is done:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(pong@gollum)1&gt; </span><span class="nc">tut18</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4610559758-1">(</span><span class="ss">ping@kosken</span><span class="p" data-group-id="4610559758-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">3934.39</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │  </span><span class="n">Pong</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">ping</span><span class="w">
│ │ │  </span><span class="n">Ping</span><span class="w"> </span><span class="ss">received</span><span class="w"> </span><span class="ss">pong</span><span class="w">
│ │ │ @@ -516,188 +516,188 @@
│ │ │  </span><span class="c1">%%% Started: messenger:client(Server_Node, Name)</span><span class="w">
│ │ │  </span><span class="c1">%%% To client: logoff</span><span class="w">
│ │ │  </span><span class="c1">%%% To client: {message_to, ToName, Message}</span><span class="w">
│ │ │  </span><span class="c1">%%%</span><span class="w">
│ │ │  </span><span class="c1">%%% Configuration: change the server_node() function to return the</span><span class="w">
│ │ │  </span><span class="c1">%%% name of the node where the messenger server runs</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0115337335-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="0115337335-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0115337335-2">(</span><span class="p" data-group-id="0115337335-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0115337335-3">]</span><span class="p" data-group-id="0115337335-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9184576408-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="9184576408-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9184576408-2">(</span><span class="p" data-group-id="9184576408-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9184576408-3">]</span><span class="p" data-group-id="9184576408-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Change the function below to return the name of the node where the</span><span class="w">
│ │ │  </span><span class="c1">%%% messenger server runs</span><span class="w">
│ │ │ -</span><span class="nf">server_node</span><span class="p" data-group-id="0115337335-4">(</span><span class="p" data-group-id="0115337335-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_node</span><span class="p" data-group-id="9184576408-4">(</span><span class="p" data-group-id="9184576408-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">messenger@super</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% This is the server process for the &quot;messenger&quot;</span><span class="w">
│ │ │  </span><span class="c1">%%% the user list has the format [{ClientPid1, Name1},{ClientPid22, Name2},...]</span><span class="w">
│ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="0115337335-5">(</span><span class="n">User_List</span><span class="p" data-group-id="0115337335-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="9184576408-5">(</span><span class="n">User_List</span><span class="p" data-group-id="9184576408-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-6">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0115337335-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="0115337335-7">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-7">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="0115337335-8">(</span><span class="n">New_User_List</span><span class="p" data-group-id="0115337335-8">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-9">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="0115337335-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="0115337335-10">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-10">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="0115337335-11">(</span><span class="n">New_User_List</span><span class="p" data-group-id="0115337335-11">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-12">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="0115337335-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-13">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0115337335-14">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-15">[</span><span class="n">User_List</span><span class="p" data-group-id="0115337335-15">]</span><span class="p" data-group-id="0115337335-14">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="0115337335-16">(</span><span class="n">User_List</span><span class="p" data-group-id="0115337335-16">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-6">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="9184576408-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="9184576408-7">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-7">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="9184576408-8">(</span><span class="n">New_User_List</span><span class="p" data-group-id="9184576408-8">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-9">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="9184576408-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="9184576408-10">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-10">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="9184576408-11">(</span><span class="n">New_User_List</span><span class="p" data-group-id="9184576408-11">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-12">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="9184576408-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-13">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9184576408-14">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-15">[</span><span class="n">User_List</span><span class="p" data-group-id="9184576408-15">]</span><span class="p" data-group-id="9184576408-14">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="9184576408-16">(</span><span class="n">User_List</span><span class="p" data-group-id="9184576408-16">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Start the server</span><span class="w">
│ │ │ -</span><span class="nf">start_server</span><span class="p" data-group-id="0115337335-17">(</span><span class="p" data-group-id="0115337335-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="0115337335-18">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="0115337335-19">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-20">[</span><span class="p" data-group-id="0115337335-21">[</span><span class="p" data-group-id="0115337335-21">]</span><span class="p" data-group-id="0115337335-20">]</span><span class="p" data-group-id="0115337335-19">)</span><span class="p" data-group-id="0115337335-18">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_server</span><span class="p" data-group-id="9184576408-17">(</span><span class="p" data-group-id="9184576408-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="9184576408-18">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="9184576408-19">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-20">[</span><span class="p" data-group-id="9184576408-21">[</span><span class="p" data-group-id="9184576408-21">]</span><span class="p" data-group-id="9184576408-20">]</span><span class="p" data-group-id="9184576408-19">)</span><span class="p" data-group-id="9184576408-18">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  
│ │ │  </span><span class="c1">%%% Server adds a new user to the user list</span><span class="w">
│ │ │ -</span><span class="nf">server_logon</span><span class="p" data-group-id="0115337335-22">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_logon</span><span class="p" data-group-id="9184576408-22">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% check if logged on anywhere else</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="0115337335-23">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-23">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="9184576408-23">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-23">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-24">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="0115337335-24">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-24">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="9184576408-24">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │              </span><span class="n">User_List</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-25">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="0115337335-25">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0115337335-26">[</span><span class="p" data-group-id="0115337335-27">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0115337335-27">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-26">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-25">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="9184576408-25">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9184576408-26">[</span><span class="p" data-group-id="9184576408-27">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="9184576408-27">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-26">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Server deletes a user from the user list</span><span class="w">
│ │ │ -</span><span class="nf">server_logoff</span><span class="p" data-group-id="0115337335-28">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="0115337335-29">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-29">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">server_logoff</span><span class="p" data-group-id="9184576408-28">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="9184576408-29">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-29">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  
│ │ │  </span><span class="c1">%%% Server transfers a message between user</span><span class="w">
│ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="0115337335-30">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="9184576408-30">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% check that the user is logged on and who he is</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="0115337335-31">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-31">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="9184576408-31">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-31">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-32">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="0115337335-32">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-33">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-34">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0115337335-34">}</span><span class="p" data-group-id="0115337335-33">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="0115337335-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-35">)</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-32">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="9184576408-32">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-33">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-34">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="9184576408-34">}</span><span class="p" data-group-id="9184576408-33">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="9184576408-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-35">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%% If the user exists, send the message</span><span class="w">
│ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="0115337335-36">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="9184576408-36">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Find the receiver and send the message</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="0115337335-37">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0115337335-37">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="9184576408-37">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9184576408-37">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-38">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="0115337335-38">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-39">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-40">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="0115337335-40">}</span><span class="p" data-group-id="0115337335-39">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-41">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-41">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="0115337335-42">}</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-38">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="9184576408-38">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-39">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-40">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="9184576408-40">}</span><span class="p" data-group-id="9184576408-39">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-41">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-41">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="9184576408-42">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  
│ │ │  </span><span class="c1">%%% User Commands</span><span class="w">
│ │ │ -</span><span class="nf">logon</span><span class="p" data-group-id="0115337335-43">(</span><span class="n">Name</span><span class="p" data-group-id="0115337335-43">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="0115337335-44">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0115337335-44">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">logon</span><span class="p" data-group-id="9184576408-43">(</span><span class="n">Name</span><span class="p" data-group-id="9184576408-43">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="9184576408-44">(</span><span class="ss">mess_client</span><span class="p" data-group-id="9184576408-44">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">register</span><span class="p" data-group-id="0115337335-45">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ -                     </span><span class="nf">spawn</span><span class="p" data-group-id="0115337335-46">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-47">[</span><span class="nf">server_node</span><span class="p" data-group-id="0115337335-48">(</span><span class="p" data-group-id="0115337335-48">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0115337335-47">]</span><span class="p" data-group-id="0115337335-46">)</span><span class="p" data-group-id="0115337335-45">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="nf">register</span><span class="p" data-group-id="9184576408-45">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ +                     </span><span class="nf">spawn</span><span class="p" data-group-id="9184576408-46">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-47">[</span><span class="nf">server_node</span><span class="p" data-group-id="9184576408-48">(</span><span class="p" data-group-id="9184576408-48">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="9184576408-47">]</span><span class="p" data-group-id="9184576408-46">)</span><span class="p" data-group-id="9184576408-45">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">already_logged_on</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">logoff</span><span class="p" data-group-id="0115337335-49">(</span><span class="p" data-group-id="0115337335-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">logoff</span><span class="p" data-group-id="9184576408-49">(</span><span class="p" data-group-id="9184576408-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">logoff</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">message</span><span class="p" data-group-id="0115337335-50">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="0115337335-51">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0115337335-51">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ +</span><span class="nf">message</span><span class="p" data-group-id="9184576408-50">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-50">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="9184576408-51">(</span><span class="ss">mess_client</span><span class="p" data-group-id="9184576408-51">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">not_logged_on</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-52">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-52">}</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-52">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-52">}</span><span class="p">,</span><span class="w">
│ │ │               </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  
│ │ │  </span><span class="c1">%%% The client process which runs on each server node</span><span class="w">
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="0115337335-53">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0115337335-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0115337335-54">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0115337335-54">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-55">{</span><span class="nf">self</span><span class="p" data-group-id="0115337335-56">(</span><span class="p" data-group-id="0115337335-56">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0115337335-55">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">await_result</span><span class="p" data-group-id="0115337335-57">(</span><span class="p" data-group-id="0115337335-57">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="0115337335-58">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0115337335-58">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="9184576408-53">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="9184576408-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9184576408-54">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="9184576408-54">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-55">{</span><span class="nf">self</span><span class="p" data-group-id="9184576408-56">(</span><span class="p" data-group-id="9184576408-56">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="9184576408-55">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">await_result</span><span class="p" data-group-id="9184576408-57">(</span><span class="p" data-group-id="9184576408-57">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="9184576408-58">(</span><span class="n">Server_Node</span><span class="p" data-group-id="9184576408-58">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="0115337335-59">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0115337335-59">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="9184576408-59">(</span><span class="n">Server_Node</span><span class="p" data-group-id="9184576408-59">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">logoff</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0115337335-60">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0115337335-60">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-61">{</span><span class="nf">self</span><span class="p" data-group-id="0115337335-62">(</span><span class="p" data-group-id="0115337335-62">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="0115337335-61">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="0115337335-63">(</span><span class="ss">normal</span><span class="p" data-group-id="0115337335-63">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-64">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-64">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0115337335-65">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0115337335-65">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0115337335-66">{</span><span class="nf">self</span><span class="p" data-group-id="0115337335-67">(</span><span class="p" data-group-id="0115337335-67">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-66">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">await_result</span><span class="p" data-group-id="0115337335-68">(</span><span class="p" data-group-id="0115337335-68">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-69">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-69">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0115337335-70">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-71">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0115337335-71">]</span><span class="p" data-group-id="0115337335-70">)</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9184576408-60">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="9184576408-60">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-61">{</span><span class="nf">self</span><span class="p" data-group-id="9184576408-62">(</span><span class="p" data-group-id="9184576408-62">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p" data-group-id="9184576408-61">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="9184576408-63">(</span><span class="ss">normal</span><span class="p" data-group-id="9184576408-63">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-64">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-64">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9184576408-65">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="9184576408-65">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9184576408-66">{</span><span class="nf">self</span><span class="p" data-group-id="9184576408-67">(</span><span class="p" data-group-id="9184576408-67">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-66">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">await_result</span><span class="p" data-group-id="9184576408-68">(</span><span class="p" data-group-id="9184576408-68">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-69">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-69">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9184576408-70">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-71">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9184576408-71">]</span><span class="p" data-group-id="9184576408-70">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="0115337335-72">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0115337335-72">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="9184576408-72">(</span><span class="n">Server_Node</span><span class="p" data-group-id="9184576408-72">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% wait for a response from the server</span><span class="w">
│ │ │ -</span><span class="nf">await_result</span><span class="p" data-group-id="0115337335-73">(</span><span class="p" data-group-id="0115337335-73">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">await_result</span><span class="p" data-group-id="9184576408-73">(</span><span class="p" data-group-id="9184576408-73">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-74">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="0115337335-74">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0115337335-75">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-76">[</span><span class="n">Why</span><span class="p" data-group-id="0115337335-76">]</span><span class="p" data-group-id="0115337335-75">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="0115337335-77">(</span><span class="ss">normal</span><span class="p" data-group-id="0115337335-77">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0115337335-78">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="0115337335-78">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0115337335-79">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0115337335-80">[</span><span class="n">What</span><span class="p" data-group-id="0115337335-80">]</span><span class="p" data-group-id="0115337335-79">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-74">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="9184576408-74">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9184576408-75">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-76">[</span><span class="n">Why</span><span class="p" data-group-id="9184576408-76">]</span><span class="p" data-group-id="9184576408-75">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="9184576408-77">(</span><span class="ss">normal</span><span class="p" data-group-id="9184576408-77">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9184576408-78">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="9184576408-78">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9184576408-79">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9184576408-80">[</span><span class="n">What</span><span class="p" data-group-id="9184576408-80">]</span><span class="p" data-group-id="9184576408-79">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>To use this program, you need to:</p><ul><li>Configure the <code class="inline">server_node()</code> function.</li><li>Copy the compiled code (<code class="inline">messenger.beam</code>) to the directory on each computer
│ │ │  where you start Erlang.</li></ul><p>In the following example using this program, nodes are started on four different
│ │ │  computers. If you do not have that many machines available on your network, you
│ │ │  can start several nodes on the same machine.</p><p>Four Erlang nodes are started up: messenger@super, c1@bilbo, c2@kosken,
│ │ │ -c3@gollum.</p><p>First the server at messenger@super is started up:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(messenger@super)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">start_server</span><span class="p" data-group-id="2029830679-1">(</span><span class="p" data-group-id="2029830679-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="ss">true</span></code></pre><p>Now Peter logs on at c1@bilbo:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="9135810273-1">(</span><span class="ss">peter</span><span class="p" data-group-id="9135810273-1">)</span><span class="p">.</span><span class="w">
│ │ │ +c3@gollum.</p><p>First the server at messenger@super is started up:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(messenger@super)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">start_server</span><span class="p" data-group-id="5200592503-1">(</span><span class="p" data-group-id="5200592503-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">true</span></code></pre><p>Now Peter logs on at c1@bilbo:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="4219966501-1">(</span><span class="ss">peter</span><span class="p" data-group-id="4219966501-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="w">
│ │ │ -</span><span class="ss">logged_on</span></code></pre><p>James logs on at c2@kosken:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="1235480551-1">(</span><span class="ss">james</span><span class="p" data-group-id="1235480551-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">logged_on</span></code></pre><p>James logs on at c2@kosken:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="0582092488-1">(</span><span class="ss">james</span><span class="p" data-group-id="0582092488-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="w">
│ │ │ -</span><span class="ss">logged_on</span></code></pre><p>And Fred logs on at c3@gollum:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c3@gollum)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="9972844727-1">(</span><span class="ss">fred</span><span class="p" data-group-id="9972844727-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">logged_on</span></code></pre><p>And Fred logs on at c3@gollum:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c3@gollum)1&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logon</span><span class="p" data-group-id="1304160501-1">(</span><span class="ss">fred</span><span class="p" data-group-id="1304160501-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="w">
│ │ │ -</span><span class="ss">logged_on</span></code></pre><p>Now Peter sends Fred a message:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="1324685487-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1324685487-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">logged_on</span></code></pre><p>Now Peter sends Fred a message:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c1@bilbo)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="7607517940-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="7607517940-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="ss">sent</span></code></pre><p>Fred receives the message and sends a message to Peter and logs off:</p><pre><code class="makeup erlang" translate="no"><span class="n">Message</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="nc">peter</span><span class="p">:</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ -(c3@gollum)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="7650753389-1">(</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;go away, I&#39;m busy&quot;</span><span class="p" data-group-id="7650753389-1">)</span><span class="p">.</span><span class="w">
│ │ │ +(c3@gollum)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="2839227764-1">(</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;go away, I&#39;m busy&quot;</span><span class="p" data-group-id="2839227764-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="nf">sent</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7650753389-2">(</span><span class="ss">c3@gollum</span><span class="p" data-group-id="7650753389-2">)</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logoff</span><span class="p" data-group-id="7650753389-3">(</span><span class="p" data-group-id="7650753389-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="ss">logoff</span></code></pre><p>James now tries to send a message to Fred:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="1725732579-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;peter doesn&#39;t like you&quot;</span><span class="p" data-group-id="1725732579-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2839227764-2">(</span><span class="ss">c3@gollum</span><span class="p" data-group-id="2839227764-2">)</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">logoff</span><span class="p" data-group-id="2839227764-3">(</span><span class="p" data-group-id="2839227764-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">logoff</span></code></pre><p>James now tries to send a message to Fred:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(c2@kosken)2&gt; </span><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="4884658173-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;peter doesn&#39;t like you&quot;</span><span class="p" data-group-id="4884658173-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="ss">receiver_not_found</span></code></pre><p>But this fails as Fred has already logged off.</p><p>First let us look at some of the new concepts that have been introduced.</p><p>There are two versions of the <code class="inline">server_transfer</code> function: one with four
│ │ │  arguments (<code class="inline">server_transfer/4</code>) and one with five (<code class="inline">server_transfer/5</code>). These
│ │ │  are regarded by Erlang as two separate functions.</p><p>Notice how to write the <code class="inline">server</code> function so that it calls itself, through
│ │ │  <code class="inline">server(User_List)</code>, and thus creates a loop. The Erlang compiler is &quot;clever&quot;
│ │ │  and optimizes the code so that this really is a sort of loop and not a proper
│ │ │  function call. But this only works if there is no code after the call.
│ │ │  Otherwise, the compiler expects the call to return and make a proper function
│ │ │  call. This would result in the process getting bigger and bigger for every loop.</p><p>Functions in the <code class="inline">lists</code> module are used. This is a very useful module and a
│ │ │  study of the manual page is recommended (<code class="inline">erl -man lists</code>).
│ │ │  <code class="inline">lists:keymember(Key,Position,Lists)</code> looks through a list of tuples and looks
│ │ │  at <code class="inline">Position</code> in each tuple to see if it is the same as <code class="inline">Key</code>. The first element
│ │ │  is position 1. If it finds a tuple where the element at <code class="inline">Position</code> is the same
│ │ │ -as <code class="inline">Key</code>, it returns <code class="inline">true</code>, otherwise <code class="inline">false</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="6876897989-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6876897989-2">[</span><span class="p" data-group-id="6876897989-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="6876897989-3">}</span><span class="p">,</span><span class="p" data-group-id="6876897989-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6876897989-4">}</span><span class="p">,</span><span class="p" data-group-id="6876897989-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6876897989-5">}</span><span class="p">,</span><span class="p" data-group-id="6876897989-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="6876897989-6">}</span><span class="p" data-group-id="6876897989-2">]</span><span class="p" data-group-id="6876897989-1">)</span><span class="p">.</span><span class="w">
│ │ │ +as <code class="inline">Key</code>, it returns <code class="inline">true</code>, otherwise <code class="inline">false</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="8272441018-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8272441018-2">[</span><span class="p" data-group-id="8272441018-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="8272441018-3">}</span><span class="p">,</span><span class="p" data-group-id="8272441018-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8272441018-4">}</span><span class="p">,</span><span class="p" data-group-id="8272441018-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8272441018-5">}</span><span class="p">,</span><span class="p" data-group-id="8272441018-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="8272441018-6">}</span><span class="p" data-group-id="8272441018-2">]</span><span class="p" data-group-id="8272441018-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="6876897989-7">(</span><span class="ss">p</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6876897989-8">[</span><span class="p" data-group-id="6876897989-9">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="6876897989-9">}</span><span class="p">,</span><span class="p" data-group-id="6876897989-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6876897989-10">}</span><span class="p">,</span><span class="p" data-group-id="6876897989-11">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6876897989-11">}</span><span class="p">,</span><span class="p" data-group-id="6876897989-12">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="6876897989-12">}</span><span class="p" data-group-id="6876897989-8">]</span><span class="p" data-group-id="6876897989-7">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="8272441018-7">(</span><span class="ss">p</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8272441018-8">[</span><span class="p" data-group-id="8272441018-9">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="8272441018-9">}</span><span class="p">,</span><span class="p" data-group-id="8272441018-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8272441018-10">}</span><span class="p">,</span><span class="p" data-group-id="8272441018-11">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8272441018-11">}</span><span class="p">,</span><span class="p" data-group-id="8272441018-12">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="8272441018-12">}</span><span class="p" data-group-id="8272441018-8">]</span><span class="p" data-group-id="8272441018-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span></code></pre><p><code class="inline">lists:keydelete</code> works in the same way but deletes the first tuple found (if
│ │ │ -any) and returns the remaining list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="3946330089-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3946330089-2">[</span><span class="p" data-group-id="3946330089-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="3946330089-3">}</span><span class="p">,</span><span class="p" data-group-id="3946330089-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3946330089-4">}</span><span class="p">,</span><span class="p" data-group-id="3946330089-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3946330089-5">}</span><span class="p">,</span><span class="p" data-group-id="3946330089-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="3946330089-6">}</span><span class="p" data-group-id="3946330089-2">]</span><span class="p" data-group-id="3946330089-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3946330089-7">[</span><span class="p" data-group-id="3946330089-8">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="3946330089-8">}</span><span class="p">,</span><span class="p" data-group-id="3946330089-9">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3946330089-9">}</span><span class="p">,</span><span class="p" data-group-id="3946330089-10">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="3946330089-10">}</span><span class="p" data-group-id="3946330089-7">]</span></code></pre><p><code class="inline">lists:keysearch</code> is like <code class="inline">lists:keymember</code>, but it returns
│ │ │ +any) and returns the remaining list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="3987029733-1">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3987029733-2">[</span><span class="p" data-group-id="3987029733-3">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="3987029733-3">}</span><span class="p">,</span><span class="p" data-group-id="3987029733-4">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3987029733-4">}</span><span class="p">,</span><span class="p" data-group-id="3987029733-5">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3987029733-5">}</span><span class="p">,</span><span class="p" data-group-id="3987029733-6">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="3987029733-6">}</span><span class="p" data-group-id="3987029733-2">]</span><span class="p" data-group-id="3987029733-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3987029733-7">[</span><span class="p" data-group-id="3987029733-8">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="3987029733-8">}</span><span class="p">,</span><span class="p" data-group-id="3987029733-9">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3987029733-9">}</span><span class="p">,</span><span class="p" data-group-id="3987029733-10">{</span><span class="ss">q</span><span class="p">,</span><span class="ss">r</span><span class="p">,</span><span class="ss">s</span><span class="p" data-group-id="3987029733-10">}</span><span class="p" data-group-id="3987029733-7">]</span></code></pre><p><code class="inline">lists:keysearch</code> is like <code class="inline">lists:keymember</code>, but it returns
│ │ │  <code class="inline">{value,Tuple_Found}</code> or the atom <code class="inline">false</code>.</p><p>There are many very useful functions in the <code class="inline">lists</code> module.</p><p>An Erlang process (conceptually) runs until it does a <code class="inline">receive</code> and there is no
│ │ │  message which it wants to receive in the message queue. &quot;conceptually&quot; is used
│ │ │  here because the Erlang system shares the CPU time between the active processes
│ │ │  in the system.</p><p>A process terminates when there is nothing more for it to do, that is, the last
│ │ │  function it calls simply returns and does not call another function. Another way
│ │ │  for a process to terminate is for it to call <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit/1</code></a>. The argument
│ │ │  to <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit/1</code></a> has a special meaning, which is discussed later. In this
│ │ │  example, <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit(normal)</code></a> is done, which has the same effect as a
│ │ │  process running out of functions to call.</p><p>The BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#whereis/1"><code class="inline">whereis(RegisteredName)</code></a> checks if a registered process
│ │ │  of name <code class="inline">RegisteredName</code> exists. If it exists, the pid of that process is
│ │ │  returned. If it does not exist, the atom <code class="inline">undefined</code> is returned.</p><p>You should by now be able to understand most of the code in the
│ │ │  messenger-module. Let us study one case in detail: a message is sent from one
│ │ │ -user to another.</p><p>The first user &quot;sends&quot; the message in the example above by:</p><pre><code class="makeup erlang" translate="no"><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="8311029603-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="8311029603-1">)</span></code></pre><p>After testing that the client process exists:</p><pre><code class="makeup erlang" translate="no"><span class="nf">whereis</span><span class="p" data-group-id="8499014986-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8499014986-1">)</span></code></pre><p>And a message is sent to <code class="inline">mess_client</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9535533183-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="9535533183-1">}</span></code></pre><p>The client sends the message to the server by:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3741435773-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="3741435773-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3741435773-2">{</span><span class="nf">self</span><span class="p" data-group-id="3741435773-3">(</span><span class="p" data-group-id="3741435773-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="3741435773-2">}</span><span class="p">,</span></code></pre><p>And waits for a reply from the server.</p><p>The server receives this message and calls:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="7203504958-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="7203504958-1">)</span><span class="p">,</span></code></pre><p>This checks that the pid <code class="inline">From</code> is in the <code class="inline">User_List</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="6438280272-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6438280272-1">)</span></code></pre><p>If <code class="inline">keysearch</code> returns the atom <code class="inline">false</code>, some error has occurred and the server
│ │ │ -sends back the message:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8785492837-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="8785492837-1">}</span></code></pre><p>This is received by the client, which in turn does <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit(normal)</code></a>
│ │ │ +user to another.</p><p>The first user &quot;sends&quot; the message in the example above by:</p><pre><code class="makeup erlang" translate="no"><span class="nc">messenger</span><span class="p">:</span><span class="nf">message</span><span class="p" data-group-id="0158949040-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0158949040-1">)</span></code></pre><p>After testing that the client process exists:</p><pre><code class="makeup erlang" translate="no"><span class="nf">whereis</span><span class="p" data-group-id="0702212965-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0702212965-1">)</span></code></pre><p>And a message is sent to <code class="inline">mess_client</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8413979303-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="8413979303-1">}</span></code></pre><p>The client sends the message to the server by:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5406950207-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="5406950207-1">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5406950207-2">{</span><span class="nf">self</span><span class="p" data-group-id="5406950207-3">(</span><span class="p" data-group-id="5406950207-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="5406950207-2">}</span><span class="p">,</span></code></pre><p>And waits for a reply from the server.</p><p>The server receives this message and calls:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="1353872264-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1353872264-1">)</span><span class="p">,</span></code></pre><p>This checks that the pid <code class="inline">From</code> is in the <code class="inline">User_List</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="2538263457-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="2538263457-1">)</span></code></pre><p>If <code class="inline">keysearch</code> returns the atom <code class="inline">false</code>, some error has occurred and the server
│ │ │ +sends back the message:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1908604044-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="1908604044-1">}</span></code></pre><p>This is received by the client, which in turn does <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit(normal)</code></a>
│ │ │  and terminates. If <code class="inline">keysearch</code> returns <code class="inline">{value,{From,Name}}</code> it is certain that
│ │ │ -the user is logged on and that his name (peter) is in variable <code class="inline">Name</code>.</p><p>Let us now call:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="5702272463-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5702272463-1">)</span></code></pre><p>Notice that as this is <code class="inline">server_transfer/5</code>, it is not the same as the previous
│ │ │ +the user is logged on and that his name (peter) is in variable <code class="inline">Name</code>.</p><p>Let us now call:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server_transfer</span><span class="p" data-group-id="6817023591-1">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6817023591-1">)</span></code></pre><p>Notice that as this is <code class="inline">server_transfer/5</code>, it is not the same as the previous
│ │ │  function <code class="inline">server_transfer/4</code>. Another <code class="inline">keysearch</code> is done on <code class="inline">User_List</code> to find
│ │ │ -the pid of the client corresponding to fred:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="9665939090-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="9665939090-1">)</span></code></pre><p>This time argument 2 is used, which is the second element in the tuple. If this
│ │ │ +the pid of the client corresponding to fred:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="1996135043-1">(</span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="1996135043-1">)</span></code></pre><p>This time argument 2 is used, which is the second element in the tuple. If this
│ │ │  returns the atom <code class="inline">false</code>, fred is not logged on and the following message is
│ │ │ -sent:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4545631223-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="4545631223-1">}</span><span class="p">;</span></code></pre><p>This is received by the client.</p><p>If <code class="inline">keysearch</code> returns:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1660969187-1">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1660969187-2">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p" data-group-id="1660969187-2">}</span><span class="p" data-group-id="1660969187-1">}</span></code></pre><p>The following message is sent to fred's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1792216462-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1792216462-1">}</span><span class="p">,</span></code></pre><p>The following message is sent to peter's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9532464423-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="9532464423-1">}</span></code></pre><p>Fred's client receives the message and prints it:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0458415010-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0458415010-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0458415010-2">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0458415010-3">[</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0458415010-3">]</span><span class="p" data-group-id="0458415010-2">)</span></code></pre><p>Peter's client receives the message in the <code class="inline">await_result</code> function.</p>
│ │ │ +sent:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0422186999-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="0422186999-1">}</span><span class="p">;</span></code></pre><p>This is received by the client.</p><p>If <code class="inline">keysearch</code> returns:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8081215234-1">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8081215234-2">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p" data-group-id="8081215234-2">}</span><span class="p" data-group-id="8081215234-1">}</span></code></pre><p>The following message is sent to fred's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9691339569-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="9691339569-1">}</span><span class="p">,</span></code></pre><p>The following message is sent to peter's client:</p><pre><code class="makeup erlang" translate="no"><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4945869614-1">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="4945869614-1">}</span></code></pre><p>Fred's client receives the message and prints it:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1269163753-1">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1269163753-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1269163753-2">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1269163753-3">[</span><span class="ss">peter</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="1269163753-3">]</span><span class="p" data-group-id="1269163753-2">)</span></code></pre><p>Peter's client receives the message in the <code class="inline">await_result</code> function.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="seq_prog.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/create_target.html
│ │ │ @@ -138,21 +138,21 @@
│ │ │    <span class="text">Creating a Target System</span>
│ │ │  </h2>
│ │ │  <p>It is assumed that you have a working Erlang/OTP system structured according to
│ │ │  the OTP design principles.</p><p><em>Step 1.</em> Create a <code class="inline">.rel</code> file (see the <a href="../../lib/sasl-4.2.2/doc/html/rel.html">rel(4)</a> manual page in
│ │ │  SASL), which specifies the ERTS version and lists all applications that are to
│ │ │  be included in the new basic target system. An example is the following
│ │ │  <code class="inline">mysystem.rel</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% mysystem.rel</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9816973293-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9816973293-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;FIRST&quot;</span><span class="p" data-group-id="9816973293-2">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9816973293-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.10.4&quot;</span><span class="p" data-group-id="9816973293-3">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9816973293-4">[</span><span class="p" data-group-id="9816973293-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.16.4&quot;</span><span class="p" data-group-id="9816973293-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9816973293-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.19.4&quot;</span><span class="p" data-group-id="9816973293-6">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9816973293-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.3.4&quot;</span><span class="p" data-group-id="9816973293-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9816973293-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="9816973293-8">}</span><span class="p" data-group-id="9816973293-4">]</span><span class="p" data-group-id="9816973293-1">}</span><span class="p">.</span></code></pre><p>The listed applications are not only original Erlang/OTP applications but
│ │ │ +</span><span class="p" data-group-id="9748991131-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9748991131-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;FIRST&quot;</span><span class="p" data-group-id="9748991131-2">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9748991131-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.10.4&quot;</span><span class="p" data-group-id="9748991131-3">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9748991131-4">[</span><span class="p" data-group-id="9748991131-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.16.4&quot;</span><span class="p" data-group-id="9748991131-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="9748991131-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.19.4&quot;</span><span class="p" data-group-id="9748991131-6">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="9748991131-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.3.4&quot;</span><span class="p" data-group-id="9748991131-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="9748991131-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="9748991131-8">}</span><span class="p" data-group-id="9748991131-4">]</span><span class="p" data-group-id="9748991131-1">}</span><span class="p">.</span></code></pre><p>The listed applications are not only original Erlang/OTP applications but
│ │ │  possibly also new applications that you have written (here exemplified by the
│ │ │  application Pea (<code class="inline">pea</code>)).</p><p><em>Step 2.</em> Start Erlang/OTP from the directory where the <code class="inline">mysystem.rel</code> file
│ │ │  resides:</p><pre><code class="text">% erl -pa /home/user/target_system/myapps/pea-1.0/ebin</code></pre><p>The <code class="inline">-pa</code> argument prepends the path to the <code class="inline">ebin</code> directory for
│ │ │  the Pea application to the code path.</p><p><em>Step 3.</em> Create the target system:</p><pre><code class="text">1&gt; target_system:create(&quot;mysystem&quot;).</code></pre><p>The function <code class="inline">target_system:create/1</code> performs the following:</p><ol><li><p>Reads the file <code class="inline">mysystem.rel</code> and creates a new file <code class="inline">plain.rel</code>.
│ │ │  The new file is identical to the original, except that it only
│ │ │  lists the Kernel and STDLIB applications.</p></li><li><p>From the files <code class="inline">mysystem.rel</code> and <code class="inline">plain.rel</code> creates the files
│ │ │  <code class="inline">mysystem.script</code>, <code class="inline">mysystem.boot</code>, <code class="inline">plain.script</code>, and <code class="inline">plain.boot</code>
│ │ │ @@ -242,25 +242,25 @@
│ │ │    <a href="#creating-the-next-version" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Creating the Next Version</span>
│ │ │  </h2>
│ │ │  <p>In this example the Pea application has been changed, and so are the
│ │ │  applications ERTS, Kernel, STDLIB and SASL.</p><p><em>Step 1.</em> Create the file <code class="inline">.rel</code>:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% mysystem2.rel</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2885076091-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2885076091-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;SECOND&quot;</span><span class="p" data-group-id="2885076091-2">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2885076091-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;6.0&quot;</span><span class="p" data-group-id="2885076091-3">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2885076091-4">[</span><span class="p" data-group-id="2885076091-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;3.0&quot;</span><span class="p" data-group-id="2885076091-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2885076091-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="2885076091-6">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2885076091-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.4&quot;</span><span class="p" data-group-id="2885076091-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2885076091-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="2885076091-8">}</span><span class="p" data-group-id="2885076091-4">]</span><span class="p" data-group-id="2885076091-1">}</span><span class="p">.</span></code></pre><p><em>Step 2.</em> Create the application upgrade file (see
│ │ │ +</span><span class="p" data-group-id="5876586291-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5876586291-2">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;SECOND&quot;</span><span class="p" data-group-id="5876586291-2">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5876586291-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;6.0&quot;</span><span class="p" data-group-id="5876586291-3">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5876586291-4">[</span><span class="p" data-group-id="5876586291-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;3.0&quot;</span><span class="p" data-group-id="5876586291-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5876586291-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="5876586291-6">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5876586291-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.4&quot;</span><span class="p" data-group-id="5876586291-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5876586291-8">{</span><span class="ss">pea</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="5876586291-8">}</span><span class="p" data-group-id="5876586291-4">]</span><span class="p" data-group-id="5876586291-1">}</span><span class="p">.</span></code></pre><p><em>Step 2.</em> Create the application upgrade file (see
│ │ │  <a href="../../lib/sasl-4.2.2/doc/html/appup.html">appup</a> in SASL) for Pea, for example:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% pea.appup</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1994649992-1">{</span><span class="s">&quot;2.0&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1994649992-2">[</span><span class="p" data-group-id="1994649992-3">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="1994649992-4">[</span><span class="p" data-group-id="1994649992-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="1994649992-5">}</span><span class="p" data-group-id="1994649992-4">]</span><span class="p" data-group-id="1994649992-3">}</span><span class="p" data-group-id="1994649992-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1994649992-6">[</span><span class="p" data-group-id="1994649992-7">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="1994649992-8">[</span><span class="p" data-group-id="1994649992-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="1994649992-9">}</span><span class="p" data-group-id="1994649992-8">]</span><span class="p" data-group-id="1994649992-7">}</span><span class="p" data-group-id="1994649992-6">]</span><span class="p" data-group-id="1994649992-1">}</span><span class="p">.</span></code></pre><p><em>Step 3.</em> From the directory where the file <code class="inline">mysystem2.rel</code> resides, start the
│ │ │ +</span><span class="p" data-group-id="5117015675-1">{</span><span class="s">&quot;2.0&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5117015675-2">[</span><span class="p" data-group-id="5117015675-3">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="5117015675-4">[</span><span class="p" data-group-id="5117015675-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="5117015675-5">}</span><span class="p" data-group-id="5117015675-4">]</span><span class="p" data-group-id="5117015675-3">}</span><span class="p" data-group-id="5117015675-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5117015675-6">[</span><span class="p" data-group-id="5117015675-7">{</span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="p" data-group-id="5117015675-8">[</span><span class="p" data-group-id="5117015675-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="ss">pea_lib</span><span class="p" data-group-id="5117015675-9">}</span><span class="p" data-group-id="5117015675-8">]</span><span class="p" data-group-id="5117015675-7">}</span><span class="p" data-group-id="5117015675-6">]</span><span class="p" data-group-id="5117015675-1">}</span><span class="p">.</span></code></pre><p><em>Step 3.</em> From the directory where the file <code class="inline">mysystem2.rel</code> resides, start the
│ │ │  Erlang/OTP system, giving the path to the new version of Pea:</p><pre><code class="text">% erl -pa /home/user/target_system/myapps/pea-2.0/ebin</code></pre><p><em>Step 4.</em> Create the release upgrade file (see <a href="../../lib/sasl-4.2.2/doc/html/relup.html">relup</a>
│ │ │  in SASL):</p><pre><code class="text">1&gt; systools:make_relup(&quot;mysystem2&quot;,[&quot;mysystem&quot;],[&quot;mysystem&quot;],
│ │ │      [{path,[&quot;/home/user/target_system/myapps/pea-1.0/ebin&quot;,
│ │ │      &quot;/my/old/erlang/lib/*/ebin&quot;]}]).</code></pre><p>Here <code class="inline">&quot;mysystem&quot;</code> is the base release and <code class="inline">&quot;mysystem2&quot;</code> is the release to
│ │ │  upgrade to.</p><p>The <code class="inline">path</code> option is used for pointing out the old version of all applications.
│ │ │  (The new versions are already in the code path - assuming of course that the
│ │ │  Erlang node on which this is executed is running the correct version of
│ │ │ @@ -292,21 +292,21 @@
│ │ │  {continue_after_restart,&quot;FIRST&quot;,[]}
│ │ │  heart: Tue Apr  1 12:15:10 2014: Erlang has closed.
│ │ │  heart: Tue Apr  1 12:15:11 2014: Executed &quot;/usr/local/erl-target/bin/start /usr/local/erl-target/releases/new_start_erl.data&quot; -&gt; 0. Terminating.
│ │ │  [End]</code></pre><p>The above return value and output after the call to
│ │ │  <a href="../../lib/sasl-4.2.2/doc/html/release_handler.html#install_release/1"><code class="inline">release_handler:install_release/1</code></a> means that the <code class="inline">release_handler</code> has
│ │ │  restarted the node by using <code class="inline">heart</code>. This is always done when the upgrade
│ │ │  involves a change of the applications ERTS, Kernel, STDLIB, or SASL. For more
│ │ │ -information, see <a href="upgrade.html">Upgrade when Erlang/OTP has Changed</a>.</p><p>The node is accessible through a new pipe:</p><pre><code class="text">% /usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</code></pre><p>List the available releases in the system:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">which_releases</span><span class="p" data-group-id="8868589940-1">(</span><span class="p" data-group-id="8868589940-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8868589940-2">[</span><span class="p" data-group-id="8868589940-3">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;SECOND&quot;</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8868589940-4">[</span><span class="s">&quot;kernel-3.0&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-2.0&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-2.0&quot;</span><span class="p" data-group-id="8868589940-4">]</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">current</span><span class="p" data-group-id="8868589940-3">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8868589940-5">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;FIRST&quot;</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8868589940-6">[</span><span class="s">&quot;kernel-2.16.4&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-1.19.4&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.3.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-1.0&quot;</span><span class="p" data-group-id="8868589940-6">]</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">permanent</span><span class="p" data-group-id="8868589940-5">}</span><span class="p" data-group-id="8868589940-2">]</span></code></pre><p>Our new release, &quot;SECOND&quot;, is now the current release, but we can also see that
│ │ │ +information, see <a href="upgrade.html">Upgrade when Erlang/OTP has Changed</a>.</p><p>The node is accessible through a new pipe:</p><pre><code class="text">% /usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</code></pre><p>List the available releases in the system:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">which_releases</span><span class="p" data-group-id="8216727669-1">(</span><span class="p" data-group-id="8216727669-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8216727669-2">[</span><span class="p" data-group-id="8216727669-3">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;SECOND&quot;</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8216727669-4">[</span><span class="s">&quot;kernel-3.0&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-2.0&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-2.0&quot;</span><span class="p" data-group-id="8216727669-4">]</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="ss">current</span><span class="p" data-group-id="8216727669-3">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8216727669-5">{</span><span class="s">&quot;MYSYSTEM&quot;</span><span class="p">,</span><span class="s">&quot;FIRST&quot;</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8216727669-6">[</span><span class="s">&quot;kernel-2.16.4&quot;</span><span class="p">,</span><span class="s">&quot;stdlib-1.19.4&quot;</span><span class="p">,</span><span class="s">&quot;sasl-2.3.4&quot;</span><span class="p">,</span><span class="s">&quot;pea-1.0&quot;</span><span class="p" data-group-id="8216727669-6">]</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="ss">permanent</span><span class="p" data-group-id="8216727669-5">}</span><span class="p" data-group-id="8216727669-2">]</span></code></pre><p>Our new release, &quot;SECOND&quot;, is now the current release, but we can also see that
│ │ │  our &quot;FIRST&quot; release is still permanent. This means that if the node would be
│ │ │  restarted now, it would come up running the &quot;FIRST&quot; release again.</p><p><em>Step 3.</em> Make the new release permanent:</p><pre><code class="text">2&gt; release_handler:make_permanent(&quot;SECOND&quot;).</code></pre><p>Check the releases again:</p><pre><code class="c">3&gt; release_handler:which_releases().
│ │ │  [{&quot;MYSYSTEM&quot;,&quot;SECOND&quot;,
│ │ │    [&quot;kernel-3.0&quot;,&quot;stdlib-2.0&quot;,&quot;sasl-2.4&quot;,&quot;pea-2.0&quot;],
│ │ │    permanent},
│ │ │   {&quot;MYSYSTEM&quot;,&quot;FIRST&quot;,
│ │ │    [&quot;kernel-2.16.4&quot;,&quot;stdlib-1.19.4&quot;,&quot;sasl-2.3.4&quot;,&quot;pea-1.0&quot;],
│ │ │ @@ -315,268 +315,268 @@
│ │ │    <a href="#listing-of-target_system-erl" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Listing of target_system.erl</span>
│ │ │  </h2>
│ │ │  <p>This module can also be found in the <code class="inline">examples</code> directory of the SASL
│ │ │  application.</p><pre><code class="makeup erlang" translate="no"><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4122306815-1">(</span><span class="ss">target_system</span><span class="p" data-group-id="4122306815-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4122306815-2">(</span><span class="p" data-group-id="4122306815-3">[</span><span class="ss">create</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">create</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">install</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="4122306815-3">]</span><span class="p" data-group-id="4122306815-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9412282344-1">(</span><span class="ss">target_system</span><span class="p" data-group-id="9412282344-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9412282344-2">(</span><span class="p" data-group-id="9412282344-3">[</span><span class="ss">create</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">create</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">install</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9412282344-3">]</span><span class="p" data-group-id="9412282344-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% Note: RelFileName below is the *stem* without trailing .rel,</span><span class="w">
│ │ │  </span><span class="c1">%% .script etc.</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% create(RelFileName)</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ -</span><span class="nf">create</span><span class="p" data-group-id="4122306815-4">(</span><span class="n">RelFileName</span><span class="p" data-group-id="4122306815-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">create</span><span class="p" data-group-id="4122306815-5">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="p" data-group-id="4122306815-6">[</span><span class="p" data-group-id="4122306815-6">]</span><span class="p" data-group-id="4122306815-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">create</span><span class="p" data-group-id="9412282344-4">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9412282344-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">create</span><span class="p" data-group-id="9412282344-5">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="p" data-group-id="9412282344-6">[</span><span class="p" data-group-id="9412282344-6">]</span><span class="p" data-group-id="9412282344-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">create</span><span class="p" data-group-id="4122306815-7">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="4122306815-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">create</span><span class="p" data-group-id="9412282344-7">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9412282344-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">RelFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Dir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="4122306815-8">(</span><span class="n">RelFileName</span><span class="p" data-group-id="4122306815-8">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">PlainRelFileName</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-9">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;plain&quot;</span><span class="p" data-group-id="4122306815-9">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Dir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="9412282344-8">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9412282344-8">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">PlainRelFileName</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-9">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;plain&quot;</span><span class="p" data-group-id="9412282344-9">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="n">PlainRelFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">PlainRelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-10">(</span><span class="s">&quot;Reading file: ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-11">[</span><span class="n">RelFile</span><span class="p" data-group-id="4122306815-11">]</span><span class="p" data-group-id="4122306815-10">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-13">[</span><span class="n">RelSpec</span><span class="p" data-group-id="4122306815-13">]</span><span class="p" data-group-id="4122306815-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">consult</span><span class="p" data-group-id="4122306815-14">(</span><span class="n">RelFile</span><span class="p" data-group-id="4122306815-14">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-15">(</span><span class="s">&quot;Creating file: ~ts from ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="4122306815-16">[</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="n">RelFile</span><span class="p" data-group-id="4122306815-16">]</span><span class="p" data-group-id="4122306815-15">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-17">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="4122306815-18">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="4122306815-18">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="4122306815-19">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="4122306815-19">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="n">AppVsns</span><span class="p" data-group-id="4122306815-17">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelSpec</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">PlainRelSpec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4122306815-20">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="4122306815-21">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="4122306815-21">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="4122306815-22">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="4122306815-22">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="4122306815-23">(</span><span class="nf">fun</span><span class="p" data-group-id="4122306815-24">(</span><span class="p" data-group-id="4122306815-25">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="4122306815-25">}</span><span class="p" data-group-id="4122306815-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-10">(</span><span class="s">&quot;Reading file: ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-11">[</span><span class="n">RelFile</span><span class="p" data-group-id="9412282344-11">]</span><span class="p" data-group-id="9412282344-10">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-13">[</span><span class="n">RelSpec</span><span class="p" data-group-id="9412282344-13">]</span><span class="p" data-group-id="9412282344-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">consult</span><span class="p" data-group-id="9412282344-14">(</span><span class="n">RelFile</span><span class="p" data-group-id="9412282344-14">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-15">(</span><span class="s">&quot;Creating file: ~ts from ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="9412282344-16">[</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="n">RelFile</span><span class="p" data-group-id="9412282344-16">]</span><span class="p" data-group-id="9412282344-15">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-17">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="9412282344-18">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="9412282344-18">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="9412282344-19">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="9412282344-19">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="n">AppVsns</span><span class="p" data-group-id="9412282344-17">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelSpec</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">PlainRelSpec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9412282344-20">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="9412282344-21">{</span><span class="n">RelName</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="9412282344-21">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="9412282344-22">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p" data-group-id="9412282344-22">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="9412282344-23">(</span><span class="nf">fun</span><span class="p" data-group-id="9412282344-24">(</span><span class="p" data-group-id="9412282344-25">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9412282344-25">}</span><span class="p" data-group-id="9412282344-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                                           </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ -                                    </span><span class="p" data-group-id="4122306815-26">(</span><span class="p" data-group-id="4122306815-27">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="4122306815-27">}</span><span class="p" data-group-id="4122306815-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                                    </span><span class="p" data-group-id="9412282344-26">(</span><span class="p" data-group-id="9412282344-27">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9412282344-27">}</span><span class="p" data-group-id="9412282344-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                                           </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ -                                    </span><span class="p" data-group-id="4122306815-28">(</span><span class="p">_</span><span class="p" data-group-id="4122306815-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                                    </span><span class="p" data-group-id="9412282344-28">(</span><span class="p">_</span><span class="p" data-group-id="9412282344-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                                           </span><span class="ss">false</span><span class="w">
│ │ │ -                                 </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsns</span><span class="p" data-group-id="4122306815-23">)</span><span class="w">
│ │ │ -                   </span><span class="p" data-group-id="4122306815-20">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="4122306815-29">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="4122306815-30">(</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-31">[</span><span class="ss">write</span><span class="p" data-group-id="4122306815-31">]</span><span class="p" data-group-id="4122306815-30">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-32">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-33">[</span><span class="n">PlainRelSpec</span><span class="p" data-group-id="4122306815-33">]</span><span class="p" data-group-id="4122306815-32">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="4122306815-34">(</span><span class="n">Fd</span><span class="p" data-group-id="4122306815-34">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-35">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -	      </span><span class="p" data-group-id="4122306815-36">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">PlainRelFileName</span><span class="p" data-group-id="4122306815-36">]</span><span class="p" data-group-id="4122306815-35">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">make_script</span><span class="p" data-group-id="4122306815-37">(</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="4122306815-37">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-38">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="4122306815-39">[</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="4122306815-39">]</span><span class="p" data-group-id="4122306815-38">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">make_script</span><span class="p" data-group-id="4122306815-40">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="4122306815-40">)</span><span class="p">,</span><span class="w">
│ │ │ +                                 </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsns</span><span class="p" data-group-id="9412282344-23">)</span><span class="w">
│ │ │ +                   </span><span class="p" data-group-id="9412282344-20">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="9412282344-29">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="9412282344-30">(</span><span class="n">PlainRelFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-31">[</span><span class="ss">write</span><span class="p" data-group-id="9412282344-31">]</span><span class="p" data-group-id="9412282344-30">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-32">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-33">[</span><span class="n">PlainRelSpec</span><span class="p" data-group-id="9412282344-33">]</span><span class="p" data-group-id="9412282344-32">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9412282344-34">(</span><span class="n">Fd</span><span class="p" data-group-id="9412282344-34">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-35">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +	      </span><span class="p" data-group-id="9412282344-36">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">PlainRelFileName</span><span class="p" data-group-id="9412282344-36">]</span><span class="p" data-group-id="9412282344-35">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">make_script</span><span class="p" data-group-id="9412282344-37">(</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9412282344-37">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-38">(</span><span class="s">&quot;Making \&quot;~ts.script\&quot; and \&quot;~ts.boot\&quot; files ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="9412282344-39">[</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="9412282344-39">]</span><span class="p" data-group-id="9412282344-38">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">make_script</span><span class="p" data-group-id="9412282344-40">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9412282344-40">)</span><span class="p">,</span><span class="w">
│ │ │  
│ │ │      </span><span class="n">TarFileName</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.tar.gz&quot;</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-41">(</span><span class="s">&quot;Creating tar file ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-42">[</span><span class="n">TarFileName</span><span class="p" data-group-id="4122306815-42">]</span><span class="p" data-group-id="4122306815-41">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">make_tar</span><span class="p" data-group-id="4122306815-43">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="4122306815-43">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-41">(</span><span class="s">&quot;Creating tar file ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-42">[</span><span class="n">TarFileName</span><span class="p" data-group-id="9412282344-42">]</span><span class="p" data-group-id="9412282344-41">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">make_tar</span><span class="p" data-group-id="9412282344-43">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">SystoolsOpts</span><span class="p" data-group-id="9412282344-43">)</span><span class="p">,</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="n">TmpDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-44">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;tmp&quot;</span><span class="p" data-group-id="4122306815-44">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-45">(</span><span class="s">&quot;Creating directory ~tp ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="4122306815-46">[</span><span class="n">TmpDir</span><span class="p" data-group-id="4122306815-46">]</span><span class="p" data-group-id="4122306815-45">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="4122306815-47">(</span><span class="n">TmpDir</span><span class="p" data-group-id="4122306815-47">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-48">(</span><span class="s">&quot;Extracting ~ts into directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-49">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="4122306815-49">]</span><span class="p" data-group-id="4122306815-48">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">extract_tar</span><span class="p" data-group-id="4122306815-50">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="n">TmpDir</span><span class="p" data-group-id="4122306815-50">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="n">TmpBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-51">(</span><span class="p" data-group-id="4122306815-52">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="4122306815-52">]</span><span class="p" data-group-id="4122306815-51">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-53">(</span><span class="p" data-group-id="4122306815-54">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="4122306815-54">]</span><span class="p" data-group-id="4122306815-53">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-55">(</span><span class="s">&quot;Deleting \&quot;erl\&quot; and \&quot;start\&quot; in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="4122306815-56">[</span><span class="n">ErtsBinDir</span><span class="p" data-group-id="4122306815-56">]</span><span class="p" data-group-id="4122306815-55">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="4122306815-57">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-58">(</span><span class="p" data-group-id="4122306815-59">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erl&quot;</span><span class="p" data-group-id="4122306815-59">]</span><span class="p" data-group-id="4122306815-58">)</span><span class="p" data-group-id="4122306815-57">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="4122306815-60">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-61">(</span><span class="p" data-group-id="4122306815-62">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="4122306815-62">]</span><span class="p" data-group-id="4122306815-61">)</span><span class="p" data-group-id="4122306815-60">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-63">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-64">[</span><span class="n">TmpBinDir</span><span class="p" data-group-id="4122306815-64">]</span><span class="p" data-group-id="4122306815-63">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="4122306815-65">(</span><span class="n">TmpBinDir</span><span class="p" data-group-id="4122306815-65">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-66">(</span><span class="s">&quot;Copying file \&quot;~ts.boot\&quot; to ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="4122306815-67">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-68">(</span><span class="p" data-group-id="4122306815-69">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="4122306815-69">]</span><span class="p" data-group-id="4122306815-68">)</span><span class="p" data-group-id="4122306815-67">]</span><span class="p" data-group-id="4122306815-66">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="4122306815-70">(</span><span class="n">PlainRelFileName</span><span class="o">++</span><span class="s">&quot;.boot&quot;</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-71">(</span><span class="p" data-group-id="4122306815-72">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="4122306815-72">]</span><span class="p" data-group-id="4122306815-71">)</span><span class="p" data-group-id="4122306815-70">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">TmpDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-44">(</span><span class="n">Dir</span><span class="p">,</span><span class="s">&quot;tmp&quot;</span><span class="p" data-group-id="9412282344-44">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-45">(</span><span class="s">&quot;Creating directory ~tp ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9412282344-46">[</span><span class="n">TmpDir</span><span class="p" data-group-id="9412282344-46">]</span><span class="p" data-group-id="9412282344-45">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="9412282344-47">(</span><span class="n">TmpDir</span><span class="p" data-group-id="9412282344-47">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-48">(</span><span class="s">&quot;Extracting ~ts into directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-49">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="9412282344-49">]</span><span class="p" data-group-id="9412282344-48">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">extract_tar</span><span class="p" data-group-id="9412282344-50">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="n">TmpDir</span><span class="p" data-group-id="9412282344-50">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="n">TmpBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-51">(</span><span class="p" data-group-id="9412282344-52">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9412282344-52">]</span><span class="p" data-group-id="9412282344-51">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-53">(</span><span class="p" data-group-id="9412282344-54">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9412282344-54">]</span><span class="p" data-group-id="9412282344-53">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-55">(</span><span class="s">&quot;Deleting \&quot;erl\&quot; and \&quot;start\&quot; in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="9412282344-56">[</span><span class="n">ErtsBinDir</span><span class="p" data-group-id="9412282344-56">]</span><span class="p" data-group-id="9412282344-55">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="9412282344-57">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-58">(</span><span class="p" data-group-id="9412282344-59">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erl&quot;</span><span class="p" data-group-id="9412282344-59">]</span><span class="p" data-group-id="9412282344-58">)</span><span class="p" data-group-id="9412282344-57">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="9412282344-60">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-61">(</span><span class="p" data-group-id="9412282344-62">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="9412282344-62">]</span><span class="p" data-group-id="9412282344-61">)</span><span class="p" data-group-id="9412282344-60">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-63">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-64">[</span><span class="n">TmpBinDir</span><span class="p" data-group-id="9412282344-64">]</span><span class="p" data-group-id="9412282344-63">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="9412282344-65">(</span><span class="n">TmpBinDir</span><span class="p" data-group-id="9412282344-65">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-66">(</span><span class="s">&quot;Copying file \&quot;~ts.boot\&quot; to ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="9412282344-67">[</span><span class="n">PlainRelFileName</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-68">(</span><span class="p" data-group-id="9412282344-69">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="9412282344-69">]</span><span class="p" data-group-id="9412282344-68">)</span><span class="p" data-group-id="9412282344-67">]</span><span class="p" data-group-id="9412282344-66">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9412282344-70">(</span><span class="n">PlainRelFileName</span><span class="o">++</span><span class="s">&quot;.boot&quot;</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-71">(</span><span class="p" data-group-id="9412282344-72">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start.boot&quot;</span><span class="p" data-group-id="9412282344-72">]</span><span class="p" data-group-id="9412282344-71">)</span><span class="p" data-group-id="9412282344-70">)</span><span class="p">,</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-73">(</span><span class="s">&quot;Copying files \&quot;epmd\&quot;, \&quot;run_erl\&quot; and \&quot;to_erl\&quot; from \n&quot;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-73">(</span><span class="s">&quot;Copying files \&quot;epmd\&quot;, \&quot;run_erl\&quot; and \&quot;to_erl\&quot; from \n&quot;</span><span class="w">
│ │ │                </span><span class="s">&quot;~ts to ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="4122306815-74">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">TmpBinDir</span><span class="p" data-group-id="4122306815-74">]</span><span class="p" data-group-id="4122306815-73">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="4122306815-75">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-76">(</span><span class="p" data-group-id="4122306815-77">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="4122306815-77">]</span><span class="p" data-group-id="4122306815-76">)</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-78">(</span><span class="p" data-group-id="4122306815-79">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="4122306815-79">]</span><span class="p" data-group-id="4122306815-78">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-80">[</span><span class="ss">preserve</span><span class="p" data-group-id="4122306815-80">]</span><span class="p" data-group-id="4122306815-75">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="4122306815-81">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-82">(</span><span class="p" data-group-id="4122306815-83">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="4122306815-83">]</span><span class="p" data-group-id="4122306815-82">)</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-84">(</span><span class="p" data-group-id="4122306815-85">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="4122306815-85">]</span><span class="p" data-group-id="4122306815-84">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-86">[</span><span class="ss">preserve</span><span class="p" data-group-id="4122306815-86">]</span><span class="p" data-group-id="4122306815-81">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="4122306815-87">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-88">(</span><span class="p" data-group-id="4122306815-89">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="4122306815-89">]</span><span class="p" data-group-id="4122306815-88">)</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-90">(</span><span class="p" data-group-id="4122306815-91">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="4122306815-91">]</span><span class="p" data-group-id="4122306815-90">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-92">[</span><span class="ss">preserve</span><span class="p" data-group-id="4122306815-92">]</span><span class="p" data-group-id="4122306815-87">)</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="9412282344-74">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">TmpBinDir</span><span class="p" data-group-id="9412282344-74">]</span><span class="p" data-group-id="9412282344-73">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9412282344-75">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-76">(</span><span class="p" data-group-id="9412282344-77">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="9412282344-77">]</span><span class="p" data-group-id="9412282344-76">)</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-78">(</span><span class="p" data-group-id="9412282344-79">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;epmd&quot;</span><span class="p" data-group-id="9412282344-79">]</span><span class="p" data-group-id="9412282344-78">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-80">[</span><span class="ss">preserve</span><span class="p" data-group-id="9412282344-80">]</span><span class="p" data-group-id="9412282344-75">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9412282344-81">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-82">(</span><span class="p" data-group-id="9412282344-83">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="9412282344-83">]</span><span class="p" data-group-id="9412282344-82">)</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-84">(</span><span class="p" data-group-id="9412282344-85">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;run_erl&quot;</span><span class="p" data-group-id="9412282344-85">]</span><span class="p" data-group-id="9412282344-84">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-86">[</span><span class="ss">preserve</span><span class="p" data-group-id="9412282344-86">]</span><span class="p" data-group-id="9412282344-81">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9412282344-87">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-88">(</span><span class="p" data-group-id="9412282344-89">[</span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="9412282344-89">]</span><span class="p" data-group-id="9412282344-88">)</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-90">(</span><span class="p" data-group-id="9412282344-91">[</span><span class="n">TmpBinDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;to_erl&quot;</span><span class="p" data-group-id="9412282344-91">]</span><span class="p" data-group-id="9412282344-90">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-92">[</span><span class="ss">preserve</span><span class="p" data-group-id="9412282344-92">]</span><span class="p" data-group-id="9412282344-87">)</span><span class="p">,</span><span class="w">
│ │ │  
│ │ │      </span><span class="c1">%% This is needed if &#39;start&#39; script created from &#39;start.src&#39; shall</span><span class="w">
│ │ │      </span><span class="c1">%% be used as it points out this directory as log dir for &#39;run_erl&#39;</span><span class="w">
│ │ │ -    </span><span class="n">TmpLogDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-93">(</span><span class="p" data-group-id="4122306815-94">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="4122306815-94">]</span><span class="p" data-group-id="4122306815-93">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-95">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-96">[</span><span class="n">TmpLogDir</span><span class="p" data-group-id="4122306815-96">]</span><span class="p" data-group-id="4122306815-95">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="4122306815-97">(</span><span class="n">TmpLogDir</span><span class="p" data-group-id="4122306815-97">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-98">(</span><span class="p" data-group-id="4122306815-99">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="4122306815-99">]</span><span class="p" data-group-id="4122306815-98">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-100">(</span><span class="s">&quot;Creating ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-101">[</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="4122306815-101">]</span><span class="p" data-group-id="4122306815-100">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">StartErlData</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">io_lib</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-102">(</span><span class="s">&quot;</span><span class="si">~s</span><span class="s"> </span><span class="si">~s</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-103">[</span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="4122306815-103">]</span><span class="p" data-group-id="4122306815-102">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">write_file</span><span class="p" data-group-id="4122306815-104">(</span><span class="n">StartErlDataFile</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="4122306815-104">)</span><span class="p">,</span><span class="w">
│ │ │ -
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-105">(</span><span class="s">&quot;Recreating tar file ~ts from contents in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -	      </span><span class="p" data-group-id="4122306815-106">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="4122306815-106">]</span><span class="p" data-group-id="4122306815-105">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-107">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tar</span><span class="p" data-group-id="4122306815-107">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="4122306815-108">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-109">[</span><span class="ss">write</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="4122306815-109">]</span><span class="p" data-group-id="4122306815-108">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">TmpLogDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-93">(</span><span class="p" data-group-id="9412282344-94">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="9412282344-94">]</span><span class="p" data-group-id="9412282344-93">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-95">(</span><span class="s">&quot;Creating temporary directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-96">[</span><span class="n">TmpLogDir</span><span class="p" data-group-id="9412282344-96">]</span><span class="p" data-group-id="9412282344-95">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">make_dir</span><span class="p" data-group-id="9412282344-97">(</span><span class="n">TmpLogDir</span><span class="p" data-group-id="9412282344-97">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-98">(</span><span class="p" data-group-id="9412282344-99">[</span><span class="n">TmpDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="9412282344-99">]</span><span class="p" data-group-id="9412282344-98">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-100">(</span><span class="s">&quot;Creating ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-101">[</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="9412282344-101">]</span><span class="p" data-group-id="9412282344-100">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">StartErlData</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">io_lib</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-102">(</span><span class="s">&quot;</span><span class="si">~s</span><span class="s"> </span><span class="si">~s</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-103">[</span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w"> </span><span class="n">RelVsn</span><span class="p" data-group-id="9412282344-103">]</span><span class="p" data-group-id="9412282344-102">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">write_file</span><span class="p" data-group-id="9412282344-104">(</span><span class="n">StartErlDataFile</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="9412282344-104">)</span><span class="p">,</span><span class="w">
│ │ │ +
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-105">(</span><span class="s">&quot;Recreating tar file ~ts from contents in directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +	      </span><span class="p" data-group-id="9412282344-106">[</span><span class="n">TarFileName</span><span class="p">,</span><span class="n">TmpDir</span><span class="p" data-group-id="9412282344-106">]</span><span class="p" data-group-id="9412282344-105">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-107">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tar</span><span class="p" data-group-id="9412282344-107">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="9412282344-108">(</span><span class="n">TarFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-109">[</span><span class="ss">write</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="9412282344-109">]</span><span class="p" data-group-id="9412282344-108">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="c1">%% {ok, Cwd} = file:get_cwd(),</span><span class="w">
│ │ │      </span><span class="c1">%% file:set_cwd(&quot;tmp&quot;),</span><span class="w">
│ │ │      </span><span class="n">ErtsDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="o">++</span><span class="n">ErtsVsn</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="4122306815-110">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-111">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="4122306815-111">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-112">[</span><span class="p" data-group-id="4122306815-112">]</span><span class="p" data-group-id="4122306815-110">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="4122306815-113">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-114">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="n">ErtsDir</span><span class="p" data-group-id="4122306815-114">)</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsDir</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-115">[</span><span class="p" data-group-id="4122306815-115">]</span><span class="p" data-group-id="4122306815-113">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="4122306815-116">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-117">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;releases&quot;</span><span class="p" data-group-id="4122306815-117">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-118">[</span><span class="p" data-group-id="4122306815-118">]</span><span class="p" data-group-id="4122306815-116">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="4122306815-119">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-120">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;lib&quot;</span><span class="p" data-group-id="4122306815-120">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;lib&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-121">[</span><span class="p" data-group-id="4122306815-121">]</span><span class="p" data-group-id="4122306815-119">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="4122306815-122">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-123">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="4122306815-123">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-124">[</span><span class="p" data-group-id="4122306815-124">]</span><span class="p" data-group-id="4122306815-122">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="4122306815-125">(</span><span class="n">Tar</span><span class="p" data-group-id="4122306815-125">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9412282344-110">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-111">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9412282344-111">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-112">[</span><span class="p" data-group-id="9412282344-112">]</span><span class="p" data-group-id="9412282344-110">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9412282344-113">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-114">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="n">ErtsDir</span><span class="p" data-group-id="9412282344-114">)</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsDir</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-115">[</span><span class="p" data-group-id="9412282344-115">]</span><span class="p" data-group-id="9412282344-113">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9412282344-116">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-117">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;releases&quot;</span><span class="p" data-group-id="9412282344-117">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-118">[</span><span class="p" data-group-id="9412282344-118">]</span><span class="p" data-group-id="9412282344-116">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9412282344-119">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-120">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;lib&quot;</span><span class="p" data-group-id="9412282344-120">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;lib&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-121">[</span><span class="p" data-group-id="9412282344-121">]</span><span class="p" data-group-id="9412282344-119">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="9412282344-122">(</span><span class="n">Tar</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-123">(</span><span class="n">TmpDir</span><span class="p">,</span><span class="s">&quot;log&quot;</span><span class="p" data-group-id="9412282344-123">)</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;log&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-124">[</span><span class="p" data-group-id="9412282344-124">]</span><span class="p" data-group-id="9412282344-122">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9412282344-125">(</span><span class="n">Tar</span><span class="p" data-group-id="9412282344-125">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="c1">%% file:set_cwd(Cwd),</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-126">(</span><span class="s">&quot;Removing directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="4122306815-127">[</span><span class="n">TmpDir</span><span class="p" data-group-id="4122306815-127">]</span><span class="p" data-group-id="4122306815-126">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="4122306815-128">(</span><span class="n">TmpDir</span><span class="p" data-group-id="4122306815-128">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-126">(</span><span class="s">&quot;Removing directory ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9412282344-127">[</span><span class="n">TmpDir</span><span class="p" data-group-id="9412282344-127">]</span><span class="p" data-group-id="9412282344-126">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="9412282344-128">(</span><span class="n">TmpDir</span><span class="p" data-group-id="9412282344-128">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  
│ │ │ -</span><span class="nf">install</span><span class="p" data-group-id="4122306815-129">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="4122306815-129">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">install</span><span class="p" data-group-id="9412282344-129">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9412282344-129">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">TarFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.tar.gz&quot;</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-130">(</span><span class="s">&quot;Extracting ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-131">[</span><span class="n">TarFile</span><span class="p" data-group-id="4122306815-131">]</span><span class="p" data-group-id="4122306815-130">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">extract_tar</span><span class="p" data-group-id="4122306815-132">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="4122306815-132">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-133">(</span><span class="p" data-group-id="4122306815-134">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="4122306815-134">]</span><span class="p" data-group-id="4122306815-133">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-135">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="4122306815-135">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="4122306815-136">(</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="4122306815-136">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-137">[</span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">RelVsn</span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="4122306815-137">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">string</span><span class="p">:</span><span class="nf">tokens</span><span class="p" data-group-id="4122306815-138">(</span><span class="n">StartErlData</span><span class="p">,</span><span class="w"> </span><span class="s">&quot; \n&quot;</span><span class="p" data-group-id="4122306815-138">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-139">(</span><span class="p" data-group-id="4122306815-140">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="4122306815-140">]</span><span class="p" data-group-id="4122306815-139">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">BinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-141">(</span><span class="p" data-group-id="4122306815-142">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="4122306815-142">]</span><span class="p" data-group-id="4122306815-141">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-143">(</span><span class="s">&quot;Substituting in erl.src, start.src and start_erl.src to &quot;</span><span class="w">
│ │ │ -              </span><span class="s">&quot;form erl, start and start_erl ...\n&quot;</span><span class="p" data-group-id="4122306815-143">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="4122306815-144">(</span><span class="p" data-group-id="4122306815-145">[</span><span class="s">&quot;erl&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="4122306815-145">]</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">BinDir</span><span class="p">,</span><span class="w">
│ │ │ -                      </span><span class="p" data-group-id="4122306815-146">[</span><span class="p" data-group-id="4122306815-147">{</span><span class="s">&quot;FINAL_ROOTDIR&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="4122306815-147">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-148">{</span><span class="s">&quot;EMU&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;beam&quot;</span><span class="p" data-group-id="4122306815-148">}</span><span class="p" data-group-id="4122306815-146">]</span><span class="p">,</span><span class="w">
│ │ │ -                      </span><span class="p" data-group-id="4122306815-149">[</span><span class="ss">preserve</span><span class="p" data-group-id="4122306815-149">]</span><span class="p" data-group-id="4122306815-144">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-130">(</span><span class="s">&quot;Extracting ~ts ...</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-131">[</span><span class="n">TarFile</span><span class="p" data-group-id="9412282344-131">]</span><span class="p" data-group-id="9412282344-130">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">extract_tar</span><span class="p" data-group-id="9412282344-132">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9412282344-132">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">StartErlDataFile</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-133">(</span><span class="p" data-group-id="9412282344-134">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl.data&quot;</span><span class="p" data-group-id="9412282344-134">]</span><span class="p" data-group-id="9412282344-133">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-135">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">StartErlData</span><span class="p" data-group-id="9412282344-135">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="9412282344-136">(</span><span class="n">StartErlDataFile</span><span class="p" data-group-id="9412282344-136">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-137">[</span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">RelVsn</span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9412282344-137">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">string</span><span class="p">:</span><span class="nf">tokens</span><span class="p" data-group-id="9412282344-138">(</span><span class="n">StartErlData</span><span class="p">,</span><span class="w"> </span><span class="s">&quot; \n&quot;</span><span class="p" data-group-id="9412282344-138">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ErtsBinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-139">(</span><span class="p" data-group-id="9412282344-140">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;erts-&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">ErlVsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9412282344-140">]</span><span class="p" data-group-id="9412282344-139">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">BinDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-141">(</span><span class="p" data-group-id="9412282344-142">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;bin&quot;</span><span class="p" data-group-id="9412282344-142">]</span><span class="p" data-group-id="9412282344-141">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-143">(</span><span class="s">&quot;Substituting in erl.src, start.src and start_erl.src to &quot;</span><span class="w">
│ │ │ +              </span><span class="s">&quot;form erl, start and start_erl ...\n&quot;</span><span class="p" data-group-id="9412282344-143">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="9412282344-144">(</span><span class="p" data-group-id="9412282344-145">[</span><span class="s">&quot;erl&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="9412282344-145">]</span><span class="p">,</span><span class="w"> </span><span class="n">ErtsBinDir</span><span class="p">,</span><span class="w"> </span><span class="n">BinDir</span><span class="p">,</span><span class="w">
│ │ │ +                      </span><span class="p" data-group-id="9412282344-146">[</span><span class="p" data-group-id="9412282344-147">{</span><span class="s">&quot;FINAL_ROOTDIR&quot;</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9412282344-147">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-148">{</span><span class="s">&quot;EMU&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;beam&quot;</span><span class="p" data-group-id="9412282344-148">}</span><span class="p" data-group-id="9412282344-146">]</span><span class="p">,</span><span class="w">
│ │ │ +                      </span><span class="p" data-group-id="9412282344-149">[</span><span class="ss">preserve</span><span class="p" data-group-id="9412282344-149">]</span><span class="p" data-group-id="9412282344-144">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="c1">%%! Workaround for pre OTP 17.0: start.src and start_erl.src did</span><span class="w">
│ │ │      </span><span class="c1">%%! not have correct permissions, so the above &#39;preserve&#39; option did not help</span><span class="w">
│ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="4122306815-150">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-151">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="4122306815-151">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="4122306815-150">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="4122306815-152">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-153">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="4122306815-153">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="4122306815-152">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="9412282344-150">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-151">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start&quot;</span><span class="p" data-group-id="9412282344-151">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="9412282344-150">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">change_mode</span><span class="p" data-group-id="9412282344-152">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-153">(</span><span class="n">BinDir</span><span class="p">,</span><span class="s">&quot;start_erl&quot;</span><span class="p" data-group-id="9412282344-153">)</span><span class="p">,</span><span class="mi">8#0755</span><span class="p" data-group-id="9412282344-152">)</span><span class="p">,</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="4122306815-154">(</span><span class="s">&quot;Creating the RELEASES file ...\n&quot;</span><span class="p" data-group-id="4122306815-154">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">create_RELEASES</span><span class="p" data-group-id="4122306815-155">(</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-156">(</span><span class="p" data-group-id="4122306815-157">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w">
│ │ │ -					    </span><span class="nc">filename</span><span class="p">:</span><span class="nf">basename</span><span class="p" data-group-id="4122306815-158">(</span><span class="n">RelFileName</span><span class="p" data-group-id="4122306815-158">)</span><span class="p" data-group-id="4122306815-157">]</span><span class="p" data-group-id="4122306815-156">)</span><span class="p" data-group-id="4122306815-155">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">fwrite</span><span class="p" data-group-id="9412282344-154">(</span><span class="s">&quot;Creating the RELEASES file ...\n&quot;</span><span class="p" data-group-id="9412282344-154">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">create_RELEASES</span><span class="p" data-group-id="9412282344-155">(</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-156">(</span><span class="p" data-group-id="9412282344-157">[</span><span class="n">RootDir</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;releases&quot;</span><span class="p">,</span><span class="w">
│ │ │ +					    </span><span class="nc">filename</span><span class="p">:</span><span class="nf">basename</span><span class="p" data-group-id="9412282344-158">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9412282344-158">)</span><span class="p" data-group-id="9412282344-157">]</span><span class="p" data-group-id="9412282344-156">)</span><span class="p" data-group-id="9412282344-155">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% LOCALS</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% make_script(RelFileName,Opts)</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ -</span><span class="nf">make_script</span><span class="p" data-group-id="4122306815-159">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="4122306815-159">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="4122306815-160">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-161">[</span><span class="ss">no_module_tests</span><span class="p">,</span><span class="w">
│ │ │ -				       </span><span class="p" data-group-id="4122306815-162">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="4122306815-163">(</span><span class="n">RelFileName</span><span class="p" data-group-id="4122306815-163">)</span><span class="p" data-group-id="4122306815-162">}</span><span class="w">
│ │ │ -				       </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="4122306815-161">]</span><span class="p" data-group-id="4122306815-160">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">make_script</span><span class="p" data-group-id="9412282344-159">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="9412282344-159">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="9412282344-160">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-161">[</span><span class="ss">no_module_tests</span><span class="p">,</span><span class="w">
│ │ │ +				       </span><span class="p" data-group-id="9412282344-162">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="9412282344-163">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9412282344-163">)</span><span class="p" data-group-id="9412282344-162">}</span><span class="w">
│ │ │ +				       </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="9412282344-161">]</span><span class="p" data-group-id="9412282344-160">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% make_tar(RelFileName,Opts)</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ -</span><span class="nf">make_tar</span><span class="p" data-group-id="4122306815-164">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="4122306815-164">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">RootDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">code</span><span class="p">:</span><span class="nf">root_dir</span><span class="p" data-group-id="4122306815-165">(</span><span class="p" data-group-id="4122306815-165">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="4122306815-166">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-167">[</span><span class="p" data-group-id="4122306815-168">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="4122306815-168">}</span><span class="p">,</span><span class="w">
│ │ │ -				    </span><span class="p" data-group-id="4122306815-169">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="4122306815-170">(</span><span class="n">RelFileName</span><span class="p" data-group-id="4122306815-170">)</span><span class="p" data-group-id="4122306815-169">}</span><span class="w">
│ │ │ -				    </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="4122306815-167">]</span><span class="p" data-group-id="4122306815-166">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">make_tar</span><span class="p" data-group-id="9412282344-164">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="n">Opts</span><span class="p" data-group-id="9412282344-164">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">RootDir</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">code</span><span class="p">:</span><span class="nf">root_dir</span><span class="p" data-group-id="9412282344-165">(</span><span class="p" data-group-id="9412282344-165">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="9412282344-166">(</span><span class="n">RelFileName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-167">[</span><span class="p" data-group-id="9412282344-168">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">RootDir</span><span class="p" data-group-id="9412282344-168">}</span><span class="p">,</span><span class="w">
│ │ │ +				    </span><span class="p" data-group-id="9412282344-169">{</span><span class="ss">outdir</span><span class="p">,</span><span class="nc">filename</span><span class="p">:</span><span class="nf">dirname</span><span class="p" data-group-id="9412282344-170">(</span><span class="n">RelFileName</span><span class="p" data-group-id="9412282344-170">)</span><span class="p" data-group-id="9412282344-169">}</span><span class="w">
│ │ │ +				    </span><span class="p">|</span><span class="n">Opts</span><span class="p" data-group-id="9412282344-167">]</span><span class="p" data-group-id="9412282344-166">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% extract_tar(TarFile, DestDir)</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ -</span><span class="nf">extract_tar</span><span class="p" data-group-id="4122306815-171">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="4122306815-171">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">extract</span><span class="p" data-group-id="4122306815-172">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-173">[</span><span class="p" data-group-id="4122306815-174">{</span><span class="ss">cwd</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="4122306815-174">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="4122306815-173">]</span><span class="p" data-group-id="4122306815-172">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">extract_tar</span><span class="p" data-group-id="9412282344-171">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="9412282344-171">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">erl_tar</span><span class="p">:</span><span class="nf">extract</span><span class="p" data-group-id="9412282344-172">(</span><span class="n">TarFile</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-173">[</span><span class="p" data-group-id="9412282344-174">{</span><span class="ss">cwd</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p" data-group-id="9412282344-174">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compressed</span><span class="p" data-group-id="9412282344-173">]</span><span class="p" data-group-id="9412282344-172">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="4122306815-175">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="4122306815-175">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="4122306815-176">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p" data-group-id="4122306815-176">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="9412282344-175">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="p" data-group-id="9412282344-175">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">create_RELEASES</span><span class="p" data-group-id="9412282344-176">(</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">RelFileName</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.rel&quot;</span><span class="p" data-group-id="9412282344-176">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="4122306815-177">(</span><span class="n">Scripts</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-177">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="4122306815-178">(</span><span class="nf">fun</span><span class="p" data-group-id="4122306815-179">(</span><span class="n">Script</span><span class="p" data-group-id="4122306815-179">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                          </span><span class="nf">subst_src_script</span><span class="p" data-group-id="4122306815-180">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w">
│ │ │ -                                           </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-180">)</span><span class="w">
│ │ │ -                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Scripts</span><span class="p" data-group-id="4122306815-178">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">subst_src_script</span><span class="p" data-group-id="4122306815-181">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-181">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst_file</span><span class="p" data-group-id="4122306815-182">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-183">(</span><span class="p" data-group-id="4122306815-184">[</span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.src&quot;</span><span class="p" data-group-id="4122306815-184">]</span><span class="p" data-group-id="4122306815-183">)</span><span class="p">,</span><span class="w">
│ │ │ -               </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-185">(</span><span class="p" data-group-id="4122306815-186">[</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="p" data-group-id="4122306815-186">]</span><span class="p" data-group-id="4122306815-185">)</span><span class="p">,</span><span class="w">
│ │ │ -               </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-182">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">subst_file</span><span class="p" data-group-id="4122306815-187">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-187">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-188">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="4122306815-188">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="4122306815-189">(</span><span class="n">Src</span><span class="p" data-group-id="4122306815-189">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">NConts</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">subst</span><span class="p" data-group-id="4122306815-190">(</span><span class="n">Conts</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="4122306815-190">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">write_file</span><span class="p" data-group-id="4122306815-191">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">NConts</span><span class="p" data-group-id="4122306815-191">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="4122306815-192">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-192">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">subst_src_scripts</span><span class="p" data-group-id="9412282344-177">(</span><span class="n">Scripts</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-177">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="9412282344-178">(</span><span class="nf">fun</span><span class="p" data-group-id="9412282344-179">(</span><span class="n">Script</span><span class="p" data-group-id="9412282344-179">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                          </span><span class="nf">subst_src_script</span><span class="p" data-group-id="9412282344-180">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w">
│ │ │ +                                           </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-180">)</span><span class="w">
│ │ │ +                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Scripts</span><span class="p" data-group-id="9412282344-178">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">subst_src_script</span><span class="p" data-group-id="9412282344-181">(</span><span class="n">Script</span><span class="p">,</span><span class="w"> </span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-181">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst_file</span><span class="p" data-group-id="9412282344-182">(</span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-183">(</span><span class="p" data-group-id="9412282344-184">[</span><span class="n">SrcDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;.src&quot;</span><span class="p" data-group-id="9412282344-184">]</span><span class="p" data-group-id="9412282344-183">)</span><span class="p">,</span><span class="w">
│ │ │ +               </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-185">(</span><span class="p" data-group-id="9412282344-186">[</span><span class="n">DestDir</span><span class="p">,</span><span class="w"> </span><span class="n">Script</span><span class="p" data-group-id="9412282344-186">]</span><span class="p" data-group-id="9412282344-185">)</span><span class="p">,</span><span class="w">
│ │ │ +               </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-182">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">subst_file</span><span class="p" data-group-id="9412282344-187">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-187">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-188">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="9412282344-188">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">read_txt_file</span><span class="p" data-group-id="9412282344-189">(</span><span class="n">Src</span><span class="p" data-group-id="9412282344-189">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">NConts</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">subst</span><span class="p" data-group-id="9412282344-190">(</span><span class="n">Conts</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="9412282344-190">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">write_file</span><span class="p" data-group-id="9412282344-191">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">NConts</span><span class="p" data-group-id="9412282344-191">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="9412282344-192">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-192">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="4122306815-193">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="4122306815-193">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="4122306815-194">(</span><span class="n">Src</span><span class="p" data-group-id="4122306815-194">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="4122306815-195">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="4122306815-195">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9412282344-193">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9412282344-193">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="9412282344-194">(</span><span class="n">Src</span><span class="p" data-group-id="9412282344-194">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="9412282344-195">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9412282344-195">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">ok</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% subst(Str, Vars)</span><span class="w">
│ │ │  </span><span class="c1">%% Vars = [{Var, Val}]</span><span class="w">
│ │ │  </span><span class="c1">%% Var = Val = string()</span><span class="w">
│ │ │  </span><span class="c1">%% Substitute all occurrences of %Var% for Val in Str, using the list</span><span class="w">
│ │ │  </span><span class="c1">%% of variables in Vars.</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="4122306815-196">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="4122306815-196">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst</span><span class="p" data-group-id="4122306815-197">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-198">[</span><span class="p" data-group-id="4122306815-198">]</span><span class="p" data-group-id="4122306815-197">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9412282344-196">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="9412282344-196">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst</span><span class="p" data-group-id="9412282344-197">(</span><span class="n">Str</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-198">[</span><span class="p" data-group-id="9412282344-198">]</span><span class="p" data-group-id="9412282344-197">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="4122306815-199">(</span><span class="p" data-group-id="4122306815-200">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-200">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-199">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$Z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="4122306815-201">(</span><span class="p" data-group-id="4122306815-202">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-202">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-203">[</span><span class="p" data-group-id="4122306815-203">]</span><span class="p" data-group-id="4122306815-201">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="4122306815-204">(</span><span class="p" data-group-id="4122306815-205">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-205">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-204">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="4122306815-206">(</span><span class="p" data-group-id="4122306815-207">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-207">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-208">[</span><span class="p" data-group-id="4122306815-208">]</span><span class="p" data-group-id="4122306815-206">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="4122306815-209">(</span><span class="p" data-group-id="4122306815-210">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-210">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-209">)</span><span class="w"> </span><span class="k">when</span><span class="w">  </span><span class="n">C</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="sc">$_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="4122306815-211">(</span><span class="p" data-group-id="4122306815-212">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-212">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-213">[</span><span class="p" data-group-id="4122306815-213">]</span><span class="p" data-group-id="4122306815-211">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="4122306815-214">(</span><span class="p" data-group-id="4122306815-215">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-215">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-214">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst</span><span class="p" data-group-id="4122306815-216">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-217">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-217">]</span><span class="p" data-group-id="4122306815-216">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">subst</span><span class="p" data-group-id="4122306815-218">(</span><span class="p" data-group-id="4122306815-219">[</span><span class="p" data-group-id="4122306815-219">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-218">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="4122306815-220">(</span><span class="n">Result</span><span class="p" data-group-id="4122306815-220">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">subst_var</span><span class="p" data-group-id="4122306815-221">(</span><span class="p" data-group-id="4122306815-222">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-222">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="4122306815-221">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Key</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="4122306815-223">(</span><span class="n">VarAcc</span><span class="p" data-group-id="4122306815-223">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="4122306815-224">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="4122306815-224">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4122306815-225">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-226">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="4122306815-226">}</span><span class="p" data-group-id="4122306815-225">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">subst</span><span class="p" data-group-id="4122306815-227">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="4122306815-228">(</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-228">)</span><span class="p" data-group-id="4122306815-227">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9412282344-199">(</span><span class="p" data-group-id="9412282344-200">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-200">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-199">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$Z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9412282344-201">(</span><span class="p" data-group-id="9412282344-202">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-202">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-203">[</span><span class="p" data-group-id="9412282344-203">]</span><span class="p" data-group-id="9412282344-201">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9412282344-204">(</span><span class="p" data-group-id="9412282344-205">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-205">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-204">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9412282344-206">(</span><span class="p" data-group-id="9412282344-207">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-207">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-208">[</span><span class="p" data-group-id="9412282344-208">]</span><span class="p" data-group-id="9412282344-206">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9412282344-209">(</span><span class="p" data-group-id="9412282344-210">[</span><span class="sc">$%</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-210">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-209">)</span><span class="w"> </span><span class="k">when</span><span class="w">  </span><span class="n">C</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="sc">$_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9412282344-211">(</span><span class="p" data-group-id="9412282344-212">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-212">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-213">[</span><span class="p" data-group-id="9412282344-213">]</span><span class="p" data-group-id="9412282344-211">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9412282344-214">(</span><span class="p" data-group-id="9412282344-215">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-215">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-214">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst</span><span class="p" data-group-id="9412282344-216">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-217">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-217">]</span><span class="p" data-group-id="9412282344-216">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">subst</span><span class="p" data-group-id="9412282344-218">(</span><span class="p" data-group-id="9412282344-219">[</span><span class="p" data-group-id="9412282344-219">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-218">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9412282344-220">(</span><span class="n">Result</span><span class="p" data-group-id="9412282344-220">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">subst_var</span><span class="p" data-group-id="9412282344-221">(</span><span class="p" data-group-id="9412282344-222">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-222">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9412282344-221">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Key</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9412282344-223">(</span><span class="n">VarAcc</span><span class="p" data-group-id="9412282344-223">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="9412282344-224">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p" data-group-id="9412282344-224">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9412282344-225">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-226">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="9412282344-226">}</span><span class="p" data-group-id="9412282344-225">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">subst</span><span class="p" data-group-id="9412282344-227">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9412282344-228">(</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-228">)</span><span class="p" data-group-id="9412282344-227">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">subst</span><span class="p" data-group-id="4122306815-229">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-230">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="4122306815-231">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-231">]</span><span class="p" data-group-id="4122306815-230">]</span><span class="p" data-group-id="4122306815-229">)</span><span class="w">
│ │ │ +            </span><span class="nf">subst</span><span class="p" data-group-id="9412282344-229">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-230">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9412282344-231">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-231">]</span><span class="p" data-group-id="9412282344-230">]</span><span class="p" data-group-id="9412282344-229">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">subst_var</span><span class="p" data-group-id="4122306815-232">(</span><span class="p" data-group-id="4122306815-233">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="4122306815-233">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="4122306815-232">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst_var</span><span class="p" data-group-id="4122306815-234">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-235">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="4122306815-235">]</span><span class="p" data-group-id="4122306815-234">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">subst_var</span><span class="p" data-group-id="4122306815-236">(</span><span class="p" data-group-id="4122306815-237">[</span><span class="p" data-group-id="4122306815-237">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="4122306815-236">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">subst</span><span class="p" data-group-id="4122306815-238">(</span><span class="p" data-group-id="4122306815-239">[</span><span class="p" data-group-id="4122306815-239">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-240">[</span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="4122306815-241">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="4122306815-241">]</span><span class="p" data-group-id="4122306815-240">]</span><span class="p" data-group-id="4122306815-238">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">copy_file</span><span class="p" data-group-id="4122306815-242">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="4122306815-242">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">copy_file</span><span class="p" data-group-id="4122306815-243">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-244">[</span><span class="p" data-group-id="4122306815-244">]</span><span class="p" data-group-id="4122306815-243">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">copy_file</span><span class="p" data-group-id="4122306815-245">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-245">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-246">{</span><span class="ss">ok</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4122306815-246">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">copy</span><span class="p" data-group-id="4122306815-247">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="4122306815-247">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="4122306815-248">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="4122306815-248">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">subst_var</span><span class="p" data-group-id="9412282344-232">(</span><span class="p" data-group-id="9412282344-233">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9412282344-233">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9412282344-232">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst_var</span><span class="p" data-group-id="9412282344-234">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-235">[</span><span class="n">C</span><span class="p">|</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9412282344-235">]</span><span class="p" data-group-id="9412282344-234">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">subst_var</span><span class="p" data-group-id="9412282344-236">(</span><span class="p" data-group-id="9412282344-237">[</span><span class="p" data-group-id="9412282344-237">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p">,</span><span class="w"> </span><span class="n">VarAcc</span><span class="p" data-group-id="9412282344-236">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">subst</span><span class="p" data-group-id="9412282344-238">(</span><span class="p" data-group-id="9412282344-239">[</span><span class="p" data-group-id="9412282344-239">]</span><span class="p">,</span><span class="w"> </span><span class="n">Vars</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-240">[</span><span class="n">VarAcc</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9412282344-241">[</span><span class="sc">$%</span><span class="p">|</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9412282344-241">]</span><span class="p" data-group-id="9412282344-240">]</span><span class="p" data-group-id="9412282344-238">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">copy_file</span><span class="p" data-group-id="9412282344-242">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="9412282344-242">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">copy_file</span><span class="p" data-group-id="9412282344-243">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-244">[</span><span class="p" data-group-id="9412282344-244">]</span><span class="p" data-group-id="9412282344-243">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">copy_file</span><span class="p" data-group-id="9412282344-245">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-245">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-246">{</span><span class="ss">ok</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9412282344-246">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">copy</span><span class="p" data-group-id="9412282344-247">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dest</span><span class="p" data-group-id="9412282344-247">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="9412282344-248">(</span><span class="ss">preserve</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9412282344-248">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="4122306815-249">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="4122306815-249">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="4122306815-250">(</span><span class="n">Src</span><span class="p" data-group-id="4122306815-250">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="4122306815-251">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="4122306815-251">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9412282344-249">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9412282344-249">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file_info</span><span class="p" data-group-id="9412282344-250">(</span><span class="n">Src</span><span class="p" data-group-id="9412282344-250">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">file</span><span class="p">:</span><span class="nf">write_file_info</span><span class="p" data-group-id="9412282344-251">(</span><span class="n">Dest</span><span class="p">,</span><span class="w"> </span><span class="n">FileInfo</span><span class="p" data-group-id="9412282344-251">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">ok</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">write_file</span><span class="p" data-group-id="4122306815-252">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="4122306815-252">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Enc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">native_name_encoding</span><span class="p" data-group-id="4122306815-253">(</span><span class="p" data-group-id="4122306815-253">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-254">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="4122306815-254">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="4122306815-255">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-256">[</span><span class="ss">write</span><span class="p" data-group-id="4122306815-256">]</span><span class="p" data-group-id="4122306815-255">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">write</span><span class="p" data-group-id="4122306815-257">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="nc">unicode</span><span class="p">:</span><span class="nf">characters_to_binary</span><span class="p" data-group-id="4122306815-258">(</span><span class="n">Conts</span><span class="p">,</span><span class="n">Enc</span><span class="p">,</span><span class="n">Enc</span><span class="p" data-group-id="4122306815-258">)</span><span class="p" data-group-id="4122306815-257">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="4122306815-259">(</span><span class="n">Fd</span><span class="p" data-group-id="4122306815-259">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">read_txt_file</span><span class="p" data-group-id="4122306815-260">(</span><span class="n">File</span><span class="p" data-group-id="4122306815-260">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-261">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="4122306815-261">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file</span><span class="p" data-group-id="4122306815-262">(</span><span class="n">File</span><span class="p" data-group-id="4122306815-262">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4122306815-263">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_list</span><span class="p" data-group-id="4122306815-264">(</span><span class="n">Bin</span><span class="p" data-group-id="4122306815-264">)</span><span class="p" data-group-id="4122306815-263">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="4122306815-265">(</span><span class="n">Dir</span><span class="p" data-group-id="4122306815-265">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">remove_all_files</span><span class="p" data-group-id="4122306815-266">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4122306815-267">[</span><span class="n">Dir</span><span class="p" data-group-id="4122306815-267">]</span><span class="p" data-group-id="4122306815-266">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">remove_all_files</span><span class="p" data-group-id="4122306815-268">(</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="4122306815-268">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="4122306815-269">(</span><span class="nf">fun</span><span class="p" data-group-id="4122306815-270">(</span><span class="n">File</span><span class="p" data-group-id="4122306815-270">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                          </span><span class="n">FilePath</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="4122306815-271">(</span><span class="p" data-group-id="4122306815-272">[</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">File</span><span class="p" data-group-id="4122306815-272">]</span><span class="p" data-group-id="4122306815-271">)</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="k">case</span><span class="w"> </span><span class="nc">filelib</span><span class="p">:</span><span class="nf">is_dir</span><span class="p" data-group-id="4122306815-273">(</span><span class="n">FilePath</span><span class="p" data-group-id="4122306815-273">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">write_file</span><span class="p" data-group-id="9412282344-252">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="n">Conts</span><span class="p" data-group-id="9412282344-252">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Enc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">native_name_encoding</span><span class="p" data-group-id="9412282344-253">(</span><span class="p" data-group-id="9412282344-253">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-254">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="9412282344-254">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="9412282344-255">(</span><span class="n">FName</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-256">[</span><span class="ss">write</span><span class="p" data-group-id="9412282344-256">]</span><span class="p" data-group-id="9412282344-255">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">write</span><span class="p" data-group-id="9412282344-257">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="nc">unicode</span><span class="p">:</span><span class="nf">characters_to_binary</span><span class="p" data-group-id="9412282344-258">(</span><span class="n">Conts</span><span class="p">,</span><span class="n">Enc</span><span class="p">,</span><span class="n">Enc</span><span class="p" data-group-id="9412282344-258">)</span><span class="p" data-group-id="9412282344-257">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9412282344-259">(</span><span class="n">Fd</span><span class="p" data-group-id="9412282344-259">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">read_txt_file</span><span class="p" data-group-id="9412282344-260">(</span><span class="n">File</span><span class="p" data-group-id="9412282344-260">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-261">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Bin</span><span class="p" data-group-id="9412282344-261">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read_file</span><span class="p" data-group-id="9412282344-262">(</span><span class="n">File</span><span class="p" data-group-id="9412282344-262">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9412282344-263">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_list</span><span class="p" data-group-id="9412282344-264">(</span><span class="n">Bin</span><span class="p" data-group-id="9412282344-264">)</span><span class="p" data-group-id="9412282344-263">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">remove_dir_tree</span><span class="p" data-group-id="9412282344-265">(</span><span class="n">Dir</span><span class="p" data-group-id="9412282344-265">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">remove_all_files</span><span class="p" data-group-id="9412282344-266">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9412282344-267">[</span><span class="n">Dir</span><span class="p" data-group-id="9412282344-267">]</span><span class="p" data-group-id="9412282344-266">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">remove_all_files</span><span class="p" data-group-id="9412282344-268">(</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="9412282344-268">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="9412282344-269">(</span><span class="nf">fun</span><span class="p" data-group-id="9412282344-270">(</span><span class="n">File</span><span class="p" data-group-id="9412282344-270">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                          </span><span class="n">FilePath</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">filename</span><span class="p">:</span><span class="nf">join</span><span class="p" data-group-id="9412282344-271">(</span><span class="p" data-group-id="9412282344-272">[</span><span class="n">Dir</span><span class="p">,</span><span class="w"> </span><span class="n">File</span><span class="p" data-group-id="9412282344-272">]</span><span class="p" data-group-id="9412282344-271">)</span><span class="p">,</span><span class="w">
│ │ │ +                          </span><span class="k">case</span><span class="w"> </span><span class="nc">filelib</span><span class="p">:</span><span class="nf">is_dir</span><span class="p" data-group-id="9412282344-273">(</span><span class="n">FilePath</span><span class="p" data-group-id="9412282344-273">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │                                </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                                  </span><span class="p" data-group-id="4122306815-274">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="4122306815-274">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">list_dir</span><span class="p" data-group-id="4122306815-275">(</span><span class="n">FilePath</span><span class="p" data-group-id="4122306815-275">)</span><span class="p">,</span><span class="w">
│ │ │ -                                  </span><span class="nf">remove_all_files</span><span class="p" data-group-id="4122306815-276">(</span><span class="n">FilePath</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="4122306815-276">)</span><span class="p">,</span><span class="w">
│ │ │ -                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">del_dir</span><span class="p" data-group-id="4122306815-277">(</span><span class="n">FilePath</span><span class="p" data-group-id="4122306815-277">)</span><span class="p">;</span><span class="w">
│ │ │ +                                  </span><span class="p" data-group-id="9412282344-274">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="9412282344-274">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">list_dir</span><span class="p" data-group-id="9412282344-275">(</span><span class="n">FilePath</span><span class="p" data-group-id="9412282344-275">)</span><span class="p">,</span><span class="w">
│ │ │ +                                  </span><span class="nf">remove_all_files</span><span class="p" data-group-id="9412282344-276">(</span><span class="n">FilePath</span><span class="p">,</span><span class="w"> </span><span class="n">DirFiles</span><span class="p" data-group-id="9412282344-276">)</span><span class="p">,</span><span class="w">
│ │ │ +                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">del_dir</span><span class="p" data-group-id="9412282344-277">(</span><span class="n">FilePath</span><span class="p" data-group-id="9412282344-277">)</span><span class="p">;</span><span class="w">
│ │ │                                </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="4122306815-278">(</span><span class="n">FilePath</span><span class="p" data-group-id="4122306815-278">)</span><span class="w">
│ │ │ +                                  </span><span class="nc">file</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="9412282344-278">(</span><span class="n">FilePath</span><span class="p" data-group-id="9412282344-278">)</span><span class="w">
│ │ │                            </span><span class="k">end</span><span class="w">
│ │ │ -                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="4122306815-269">)</span><span class="p">.</span></code></pre>
│ │ │ +                  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Files</span><span class="p" data-group-id="9412282344-269">)</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="error_logging.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/data_types.html
│ │ │ @@ -192,18 +192,18 @@
│ │ │    </a>
│ │ │    <span class="text">Representation of Floating Point Numbers</span>
│ │ │  </h3>
│ │ │  <p>When working with floats you may not see what you expect when printing or doing
│ │ │  arithmetic operations. This is because floats are represented by a fixed number
│ │ │  of bits in a base-2 system while printed floats are represented with a base-10
│ │ │  system. Erlang uses 64-bit floats. Here are examples of this phenomenon:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mf">0.30000000000000004</span></code></pre><p>The real numbers <code class="inline">0.1</code> and <code class="inline">0.2</code> cannot be represented exactly as floats.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="6290589503-1">{</span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963968</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="mf">36028797018963970.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963970</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963970.0</span><span class="p" data-group-id="6290589503-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6290589503-2">{</span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="6290589503-2">}</span><span class="p">.</span></code></pre><p>The value <code class="inline">36028797018963968</code> can be represented exactly as a float value but
│ │ │ +</span><span class="mf">0.30000000000000004</span></code></pre><p>The real numbers <code class="inline">0.1</code> and <code class="inline">0.2</code> cannot be represented exactly as floats.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7534692424-1">{</span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963968</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963968.0</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="mf">36028797018963970.0</span><span class="p">,</span><span class="w"> </span><span class="mi">36028797018963970</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mf">36028797018963970.0</span><span class="p" data-group-id="7534692424-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7534692424-2">{</span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="mf">3.602879701896397e16</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="7534692424-2">}</span><span class="p">.</span></code></pre><p>The value <code class="inline">36028797018963968</code> can be represented exactly as a float value but
│ │ │  Erlang's pretty printer rounds <code class="inline">36028797018963968.0</code> to <code class="inline">3.602879701896397e16</code>
│ │ │  (<code class="inline">=36028797018963970.0</code>) as all values in the range
│ │ │  <code class="inline">[36028797018963966.0, 36028797018963972.0]</code> are represented by
│ │ │  <code class="inline">36028797018963968.0</code>.</p><p>For more information about floats and issues with them see:</p><ul><li><a href="https://floating-point-gui.de/">What Every Programmer Should Know About Floating-Point Arithmetic</a></li><li><a href="https://0.30000000000000004.com/">0.30000000000000004.com/</a></li><li><a href="https://docs.python.org/3/tutorial/floatingpoint.html">Floating Point Arithmetic: Issues and Limitations</a></li></ul><p>If you need to work with exact decimal fractions, for instance to represent
│ │ │  money, it is recommended to use a library that handles that, or work in
│ │ │  cents instead of dollars or euros so that decimal fractions are not needed.</p><p>Also note that Erlang's floats do not exactly match IEEE 754 floats,
│ │ │  in that neither <em>Inf</em> nor <em>NaN</em> are supported in Erlang. Any
│ │ │ @@ -237,52 +237,52 @@
│ │ │  by eight are called <em>binaries</em>.</p><p><em>Examples:</em></p><pre><code class="text">1&gt; &lt;&lt;10,20&gt;&gt;.
│ │ │  &lt;&lt;10,20&gt;&gt;
│ │ │  2&gt; &lt;&lt;&quot;ABC&quot;&gt;&gt;.
│ │ │  &lt;&lt;&quot;ABC&quot;&gt;&gt;
│ │ │  3&gt; &lt;&lt;1:1,0:1&gt;&gt;.
│ │ │  &lt;&lt;2:2&gt;&gt;</code></pre><p>The <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_bitstring/1"><code class="inline">is_bitstring/1</code></a> BIF tests whether a
│ │ │  term is a bit string, and the <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_binary/1"><code class="inline">is_binary/1</code></a>
│ │ │ -BIF tests whether a term is a binary.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">is_bitstring</span><span class="p" data-group-id="2108201644-1">(</span><span class="p" data-group-id="2108201644-2">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2108201644-2">&gt;&gt;</span><span class="p" data-group-id="2108201644-1">)</span><span class="p">.</span><span class="w">
│ │ │ +BIF tests whether a term is a binary.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">is_bitstring</span><span class="p" data-group-id="7247106356-1">(</span><span class="p" data-group-id="7247106356-2">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="7247106356-2">&gt;&gt;</span><span class="p" data-group-id="7247106356-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="2108201644-3">(</span><span class="p" data-group-id="2108201644-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2108201644-4">&gt;&gt;</span><span class="p" data-group-id="2108201644-3">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="7247106356-3">(</span><span class="p" data-group-id="7247106356-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="7247106356-4">&gt;&gt;</span><span class="p" data-group-id="7247106356-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="2108201644-5">(</span><span class="p" data-group-id="2108201644-6">&lt;&lt;</span><span class="mi">42</span><span class="p" data-group-id="2108201644-6">&gt;&gt;</span><span class="p" data-group-id="2108201644-5">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nf">is_binary</span><span class="p" data-group-id="7247106356-5">(</span><span class="p" data-group-id="7247106356-6">&lt;&lt;</span><span class="mi">42</span><span class="p" data-group-id="7247106356-6">&gt;&gt;</span><span class="p" data-group-id="7247106356-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="w">
│ │ │  </span></code></pre><p>For more examples, see <a href="../../doc/system/bit_syntax.html">Programming Examples</a>.</p><h2 id="reference" class="section-heading">
│ │ │    <a href="#reference" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Reference</span>
│ │ │  </h2>
│ │ │  <p>A term that is <a href="../../doc/system/system_limits.html#unique_references">unique</a>
│ │ │  among connected nodes. A reference is created by calling the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#make_ref/0"><code class="inline">make_ref/0</code></a> BIF. The
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_reference/1"><code class="inline">is_reference/1</code></a> BIF tests whether a term
│ │ │ -is a reference.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="6918729840-1">(</span><span class="p" data-group-id="6918729840-1">)</span><span class="p">.</span><span class="w">
│ │ │ +is a reference.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="8168502205-1">(</span><span class="p" data-group-id="8168502205-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Ref</span><span class="o">&lt;</span><span class="mf">0.76482849</span><span class="p">.</span><span class="mf">3801088007.198204</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">is_reference</span><span class="p" data-group-id="6918729840-2">(</span><span class="n">Ref</span><span class="p" data-group-id="6918729840-2">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nf">is_reference</span><span class="p" data-group-id="8168502205-2">(</span><span class="n">Ref</span><span class="p" data-group-id="8168502205-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><h2 id="fun" class="section-heading">
│ │ │    <a href="#fun" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Fun</span>
│ │ │  </h2>
│ │ │  <p>A fun is a functional object. Funs make it possible to create an anonymous
│ │ │  function and pass the function itself — not its name — as argument to other
│ │ │ -functions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2745729125-1">(</span><span class="n">X</span><span class="p" data-group-id="2745729125-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +functions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="1003937562-1">(</span><span class="n">X</span><span class="p" data-group-id="1003937562-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="2745729125-2">(</span><span class="mi">2</span><span class="p" data-group-id="2745729125-2">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="1003937562-2">(</span><span class="mi">2</span><span class="p" data-group-id="1003937562-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span></code></pre><p>The <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_function/1"><code class="inline">is_function/1</code></a> and <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_function/2"><code class="inline">is_function/2</code></a>
│ │ │ -BIFs tests whether a term is a fun.</p><p><em>Examples</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4014383854-1">(</span><span class="p" data-group-id="4014383854-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +BIFs tests whether a term is a fun.</p><p><em>Examples</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4140455080-1">(</span><span class="p" data-group-id="4140455080-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">43.105768164</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4014383854-2">(</span><span class="n">F</span><span class="p" data-group-id="4014383854-2">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4140455080-2">(</span><span class="n">F</span><span class="p" data-group-id="4140455080-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4014383854-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4014383854-3">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4140455080-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4140455080-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4014383854-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4014383854-4">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nf">is_function</span><span class="p" data-group-id="4140455080-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4140455080-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span></code></pre><p>Read more about funs in <a href="expressions.html#fun-expressions">Fun Expressions</a>. For more
│ │ │  examples, see <a href="../../doc/system/funs.html">Programming Examples</a>.</p><h2 id="port-identifier" class="section-heading">
│ │ │    <a href="#port-identifier" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Port Identifier</span>
│ │ │  </h2>
│ │ │ @@ -300,94 +300,94 @@
│ │ │  for a new process after a while.</p><p>The BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#self/0"><code class="inline">self/0</code></a> returns the Pid of the calling process. When
│ │ │  <a href="ref_man_processes.html#process-creation">creating a new process</a>, the parent
│ │ │  process will be able to get the Pid of the child process either via the return
│ │ │  value, as is the case when calling the <a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn/3"><code class="inline">spawn/3</code></a> BIF, or via
│ │ │  a message, which is the case when calling the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn_request/5"><code class="inline">spawn_request/5</code></a> BIF. A Pid is typically used when
│ │ │  when sending a process a <a href="ref_man_processes.html#signals">signal</a>. The
│ │ │ -<a href="../../erts-15.2.7.3/doc/html/erlang.html#is_pid/1"><code class="inline">is_pid/1</code></a> BIF tests whether a term is a Pid.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9023402367-1">(</span><span class="ss">m</span><span class="p" data-group-id="9023402367-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9023402367-2">(</span><span class="p" data-group-id="9023402367-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9023402367-3">]</span><span class="p" data-group-id="9023402367-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<a href="../../erts-15.2.7.3/doc/html/erlang.html#is_pid/1"><code class="inline">is_pid/1</code></a> BIF tests whether a term is a Pid.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5198914879-1">(</span><span class="ss">m</span><span class="p" data-group-id="5198914879-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5198914879-2">(</span><span class="p" data-group-id="5198914879-3">[</span><span class="ss">loop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5198914879-3">]</span><span class="p" data-group-id="5198914879-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="9023402367-4">(</span><span class="p" data-group-id="9023402367-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="5198914879-4">(</span><span class="p" data-group-id="5198914879-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">who_are_you</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9023402367-5">(</span><span class="s">&quot;I am </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9023402367-6">[</span><span class="nf">self</span><span class="p" data-group-id="9023402367-7">(</span><span class="p" data-group-id="9023402367-7">)</span><span class="p" data-group-id="9023402367-6">]</span><span class="p" data-group-id="9023402367-5">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="9023402367-8">(</span><span class="p" data-group-id="9023402367-8">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5198914879-5">(</span><span class="s">&quot;I am </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5198914879-6">[</span><span class="nf">self</span><span class="p" data-group-id="5198914879-7">(</span><span class="p" data-group-id="5198914879-7">)</span><span class="p" data-group-id="5198914879-6">]</span><span class="p" data-group-id="5198914879-5">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="5198914879-8">(</span><span class="p" data-group-id="5198914879-8">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="9023402367-9">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">loop</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9023402367-10">[</span><span class="p" data-group-id="9023402367-10">]</span><span class="p" data-group-id="9023402367-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="5198914879-9">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">loop</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5198914879-10">[</span><span class="p" data-group-id="5198914879-10">]</span><span class="p" data-group-id="5198914879-9">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.58</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │  2&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">who_are_you</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="n">I</span><span class="w"> </span><span class="ss">am</span><span class="w"> </span><span class="o">&lt;</span><span class="mf">0.58</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="ss">who_are_you</span></code></pre><p>Read more about processes in <a href="ref_man_processes.html">Processes</a>.</p><h2 id="tuple" class="section-heading">
│ │ │    <a href="#tuple" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Tuple</span>
│ │ │  </h2>
│ │ │  <p>A tuple is a compound data type with a fixed number of terms:</p><pre><code class="text">{Term1,...,TermN}</code></pre><p>Each term <code class="inline">Term</code> in the tuple is called an <em>element</em>. The number of elements is
│ │ │ -said to be the <em>size</em> of the tuple.</p><p>There exists a number of BIFs to manipulate tuples.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3260530244-1">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="3260530244-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="3260530244-2">}</span><span class="p" data-group-id="3260530244-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3260530244-3">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="3260530244-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="3260530244-4">}</span><span class="p" data-group-id="3260530244-3">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">element</span><span class="p" data-group-id="3260530244-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="3260530244-5">)</span><span class="p">.</span><span class="w">
│ │ │ +said to be the <em>size</em> of the tuple.</p><p>There exists a number of BIFs to manipulate tuples.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4544231876-1">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="4544231876-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="4544231876-2">}</span><span class="p" data-group-id="4544231876-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4544231876-3">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">24</span><span class="p">,</span><span class="p" data-group-id="4544231876-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="4544231876-4">}</span><span class="p" data-group-id="4544231876-3">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nf">element</span><span class="p" data-group-id="4544231876-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="4544231876-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">adam</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nf">element</span><span class="p" data-group-id="3260530244-6">(</span><span class="mi">3</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="3260530244-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3260530244-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="3260530244-7">}</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="3260530244-8">(</span><span class="mi">2</span><span class="p">,</span><span class="n">P</span><span class="p">,</span><span class="mi">25</span><span class="p" data-group-id="3260530244-8">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3260530244-9">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">25</span><span class="p">,</span><span class="p" data-group-id="3260530244-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="3260530244-10">}</span><span class="p" data-group-id="3260530244-9">}</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="3260530244-11">(</span><span class="n">P</span><span class="p" data-group-id="3260530244-11">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nf">element</span><span class="p" data-group-id="4544231876-6">(</span><span class="mi">3</span><span class="p">,</span><span class="n">P</span><span class="p" data-group-id="4544231876-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4544231876-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="4544231876-7">}</span><span class="gp unselectable">
│ │ │ +4&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">setelement</span><span class="p" data-group-id="4544231876-8">(</span><span class="mi">2</span><span class="p">,</span><span class="n">P</span><span class="p">,</span><span class="mi">25</span><span class="p" data-group-id="4544231876-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4544231876-9">{</span><span class="ss">adam</span><span class="p">,</span><span class="mi">25</span><span class="p">,</span><span class="p" data-group-id="4544231876-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="4544231876-10">}</span><span class="p" data-group-id="4544231876-9">}</span><span class="gp unselectable">
│ │ │ +5&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="4544231876-11">(</span><span class="n">P</span><span class="p" data-group-id="4544231876-11">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="3260530244-12">(</span><span class="p" data-group-id="3260530244-13">{</span><span class="p" data-group-id="3260530244-13">}</span><span class="p" data-group-id="3260530244-12">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="4544231876-12">(</span><span class="p" data-group-id="4544231876-13">{</span><span class="p" data-group-id="4544231876-13">}</span><span class="p" data-group-id="4544231876-12">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">0</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="3260530244-14">(</span><span class="p" data-group-id="3260530244-15">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3260530244-15">}</span><span class="p" data-group-id="3260530244-14">)</span><span class="p">.</span><span class="w">
│ │ │ +7&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="4544231876-14">(</span><span class="p" data-group-id="4544231876-15">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="4544231876-15">}</span><span class="p" data-group-id="4544231876-14">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><h2 id="map" class="section-heading">
│ │ │    <a href="#map" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Map</span>
│ │ │  </h2>
│ │ │  <p>A map is a compound data type with a variable number of key-value associations:</p><pre><code class="text">#{Key1 =&gt; Value1, ..., KeyN =&gt; ValueN}</code></pre><p>Each key-value association in the map is called an <em>association pair</em>. The key
│ │ │  and value parts of the pair are called <em>elements</em>. The number of association
│ │ │ -pairs is said to be the <em>size</em> of the map.</p><p>There exists a number of BIFs to manipulate maps.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1343563013-1">#{</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="w"> </span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1343563013-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="1343563013-2">}</span><span class="p" data-group-id="1343563013-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1343563013-3">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1343563013-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="1343563013-4">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="1343563013-3">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="1343563013-5">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="1343563013-5">)</span><span class="p">.</span><span class="w">
│ │ │ +pairs is said to be the <em>size</em> of the map.</p><p>There exists a number of BIFs to manipulate maps.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9451304203-1">#{</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="w"> </span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9451304203-2">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="9451304203-2">}</span><span class="p" data-group-id="9451304203-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9451304203-3">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">24</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9451304203-4">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="9451304203-4">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="9451304203-3">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="9451304203-5">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="9451304203-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">adam</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="1343563013-6">(</span><span class="ss">date</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="1343563013-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1343563013-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="1343563013-7">}</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="1343563013-8">(</span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="1343563013-8">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1343563013-9">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1343563013-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="1343563013-10">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="1343563013-9">}</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="1343563013-11">(</span><span class="n">M</span><span class="p" data-group-id="1343563013-11">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">maps</span><span class="p">:</span><span class="nf">get</span><span class="p" data-group-id="9451304203-6">(</span><span class="ss">date</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="9451304203-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9451304203-7">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="9451304203-7">}</span><span class="gp unselectable">
│ │ │ +4&gt; </span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="9451304203-8">(</span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="9451304203-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9451304203-9">#{</span><span class="ss">age</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">25</span><span class="p">,</span><span class="ss">date</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9451304203-10">{</span><span class="ss">july</span><span class="p">,</span><span class="mi">29</span><span class="p" data-group-id="9451304203-10">}</span><span class="p">,</span><span class="ss">name</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">adam</span><span class="p" data-group-id="9451304203-9">}</span><span class="gp unselectable">
│ │ │ +5&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="9451304203-11">(</span><span class="n">M</span><span class="p" data-group-id="9451304203-11">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="1343563013-12">(</span><span class="p" data-group-id="1343563013-13">#{</span><span class="p" data-group-id="1343563013-13">}</span><span class="p" data-group-id="1343563013-12">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="9451304203-12">(</span><span class="p" data-group-id="9451304203-13">#{</span><span class="p" data-group-id="9451304203-13">}</span><span class="p" data-group-id="9451304203-12">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">0</span></code></pre><p>A collection of maps processing functions are found in module <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html"><code class="inline">maps</code></a>
│ │ │  in STDLIB.</p><p>Read more about maps in <a href="expressions.html#map-expressions">Map Expressions</a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Maps were introduced as an experimental feature in Erlang/OTP R17. Their
│ │ │  functionality was extended and became fully supported in Erlang/OTP 18.</p></section><h2 id="list" class="section-heading">
│ │ │    <a href="#list" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">List</span>
│ │ │  </h2>
│ │ │  <p>A list is a compound data type with a variable number of terms.</p><pre><code class="text">[Term1,...,TermN]</code></pre><p>Each term <code class="inline">Term</code> in the list is called an <em>element</em>. The number of elements is
│ │ │  said to be the <em>length</em> of the list.</p><p>Formally, a list is either the empty list <code class="inline">[]</code> or consists of a <em>head</em> (first
│ │ │  element) and a <em>tail</em> (remainder of the list). The <em>tail</em> is also a list. The
│ │ │  latter can be expressed as <code class="inline">[H|T]</code>. The notation <code class="inline">[Term1,...,TermN]</code> above is
│ │ │  equivalent with the list <code class="inline">[Term1|[...|[TermN|[]]]]</code>.</p><p><em>Example:</em></p><p><code class="inline">[]</code> is a list, thus<br/><code class="inline">[c|[]]</code> is a list, thus<br/><code class="inline">[b|[c|[]]]</code> is a list, thus<br/><code class="inline">[a|[b|[c|[]]]]</code> is a list, or in short <code class="inline">[a,b,c]</code></p><p>A list where the tail is a list is sometimes called a <em>proper list</em>. It is
│ │ │  allowed to have a list where the tail is not a list, for example, <code class="inline">[a|b]</code>.
│ │ │ -However, this type of list is of little practical use.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6785706198-1">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6785706198-2">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6785706198-2">}</span><span class="p" data-group-id="6785706198-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6785706198-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6785706198-4">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6785706198-4">}</span><span class="p" data-group-id="6785706198-3">]</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="6785706198-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6785706198-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L1</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6785706198-6">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6785706198-7">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6785706198-7">}</span><span class="p" data-group-id="6785706198-6">]</span><span class="gp unselectable">
│ │ │ +However, this type of list is of little practical use.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0997657298-1">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="0997657298-2">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0997657298-2">}</span><span class="p" data-group-id="0997657298-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0997657298-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="0997657298-4">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0997657298-4">}</span><span class="p" data-group-id="0997657298-3">]</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="0997657298-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0997657298-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L1</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0997657298-6">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="0997657298-7">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0997657298-7">}</span><span class="p" data-group-id="0997657298-6">]</span><span class="gp unselectable">
│ │ │  3&gt; </span><span class="n">H</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">a</span><span class="gp unselectable">
│ │ │  4&gt; </span><span class="n">T</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6785706198-8">[</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6785706198-9">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6785706198-9">}</span><span class="p" data-group-id="6785706198-8">]</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="n">L2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6785706198-10">[</span><span class="ss">d</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6785706198-10">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6785706198-11">[</span><span class="ss">d</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="6785706198-12">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6785706198-12">}</span><span class="p" data-group-id="6785706198-11">]</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nf">length</span><span class="p" data-group-id="6785706198-13">(</span><span class="n">L1</span><span class="p" data-group-id="6785706198-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0997657298-8">[</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="0997657298-9">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0997657298-9">}</span><span class="p" data-group-id="0997657298-8">]</span><span class="gp unselectable">
│ │ │ +5&gt; </span><span class="n">L2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0997657298-10">[</span><span class="ss">d</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0997657298-10">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0997657298-11">[</span><span class="ss">d</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="0997657298-12">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0997657298-12">}</span><span class="p" data-group-id="0997657298-11">]</span><span class="gp unselectable">
│ │ │ +6&gt; </span><span class="nf">length</span><span class="p" data-group-id="0997657298-13">(</span><span class="n">L1</span><span class="p" data-group-id="0997657298-13">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="nf">length</span><span class="p" data-group-id="6785706198-14">(</span><span class="p" data-group-id="6785706198-15">[</span><span class="p" data-group-id="6785706198-15">]</span><span class="p" data-group-id="6785706198-14">)</span><span class="p">.</span><span class="w">
│ │ │ +7&gt; </span><span class="nf">length</span><span class="p" data-group-id="0997657298-14">(</span><span class="p" data-group-id="0997657298-15">[</span><span class="p" data-group-id="0997657298-15">]</span><span class="p" data-group-id="0997657298-14">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">0</span></code></pre><p>A collection of list processing functions are found in module
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html"><code class="inline">lists</code></a> in STDLIB.</p><h2 id="string" class="section-heading">
│ │ │    <a href="#string" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">String</span>
│ │ │  </h2>
│ │ │ @@ -507,41 +507,41 @@
│ │ │    <span class="text">Record</span>
│ │ │  </h2>
│ │ │  <p>A record is a data structure for storing a fixed number of elements. It has
│ │ │  named fields and is similar to a struct in C. However, a record is not a true
│ │ │  data type. Instead, record expressions are translated to tuple expressions
│ │ │  during compilation. Therefore, record expressions are not understood by the
│ │ │  shell unless special actions are taken. For details, see module <a href="../../lib/stdlib-6.2.2.2/doc/html/shell.html"><code class="inline">shell</code></a>
│ │ │ -in STDLIB.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6956807769-1">(</span><span class="ss">person</span><span class="p" data-group-id="6956807769-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6956807769-2">(</span><span class="p" data-group-id="6956807769-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6956807769-3">]</span><span class="p" data-group-id="6956807769-2">)</span><span class="p">.</span><span class="w">
│ │ │ +in STDLIB.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2950881600-1">(</span><span class="ss">person</span><span class="p" data-group-id="2950881600-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2950881600-2">(</span><span class="p" data-group-id="2950881600-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2950881600-3">]</span><span class="p" data-group-id="2950881600-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6956807769-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6956807769-5">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="6956807769-5">}</span><span class="p" data-group-id="6956807769-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2950881600-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2950881600-5">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="2950881600-5">}</span><span class="p" data-group-id="2950881600-4">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">new</span><span class="p" data-group-id="6956807769-6">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="6956807769-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6956807769-7">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="o">=</span><span class="n">Age</span><span class="p" data-group-id="6956807769-7">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">new</span><span class="p" data-group-id="2950881600-6">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="2950881600-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2950881600-7">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="o">=</span><span class="n">Age</span><span class="p" data-group-id="2950881600-7">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">person</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="6956807769-8">(</span><span class="ss">ernie</span><span class="p">,</span><span class="w"> </span><span class="mi">44</span><span class="p" data-group-id="6956807769-8">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6956807769-9">{</span><span class="ss">person</span><span class="p">,</span><span class="ss">ernie</span><span class="p">,</span><span class="mi">44</span><span class="p" data-group-id="6956807769-9">}</span></code></pre><p>Read more about records in <a href="ref_man_records.html">Records</a>. More examples are
│ │ │ +</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nc">person</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="2950881600-8">(</span><span class="ss">ernie</span><span class="p">,</span><span class="w"> </span><span class="mi">44</span><span class="p" data-group-id="2950881600-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2950881600-9">{</span><span class="ss">person</span><span class="p">,</span><span class="ss">ernie</span><span class="p">,</span><span class="mi">44</span><span class="p" data-group-id="2950881600-9">}</span></code></pre><p>Read more about records in <a href="ref_man_records.html">Records</a>. More examples are
│ │ │  found in <a href="../../doc/system/prog_ex_records.html">Programming Examples</a>.</p><h2 id="boolean" class="section-heading">
│ │ │    <a href="#boolean" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Boolean</span>
│ │ │  </h2>
│ │ │  <p>There is no Boolean data type in Erlang. Instead the atoms <code class="inline">true</code> and <code class="inline">false</code>
│ │ │  are used to denote Boolean values. The <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_boolean/1"><code class="inline">is_boolean/1</code></a>
│ │ │  BIF tests whether a term is a boolean.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="mi">2</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │  2&gt; </span><span class="ss">true</span><span class="w"> </span><span class="ow">or</span><span class="w"> </span><span class="ss">false</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="3049840527-1">(</span><span class="ss">true</span><span class="p" data-group-id="3049840527-1">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="8766750606-1">(</span><span class="ss">true</span><span class="p" data-group-id="8766750606-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="3049840527-2">(</span><span class="ss">false</span><span class="p" data-group-id="3049840527-2">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="8766750606-2">(</span><span class="ss">false</span><span class="p" data-group-id="8766750606-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="3049840527-3">(</span><span class="ss">ok</span><span class="p" data-group-id="3049840527-3">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nf">is_boolean</span><span class="p" data-group-id="8766750606-3">(</span><span class="ss">ok</span><span class="p" data-group-id="8766750606-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span></code></pre><h2 id="escape-sequences" class="section-heading">
│ │ │    <a href="#escape-sequences" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Escape Sequences</span>
│ │ │  </h2>
│ │ │  <p>Within strings (<code class="inline">&quot;</code>-delimited), quoted atoms, and the content of
│ │ │ @@ -559,47 +559,47 @@
│ │ │  <a href="data_types.html#sigil"><code class="inline">~b</code> or <code class="inline">~s</code> sigils </a>the escape sequences for normal
│ │ │  strings, above, are used.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Triple-quoted strings and sigils were introduced in Erlang/OTP 27.</p></section><h2 id="type-conversions" class="section-heading">
│ │ │    <a href="#type-conversions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Type Conversions</span>
│ │ │  </h2>
│ │ │ -<p>There are a number of BIFs for type conversions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="8952612466-1">(</span><span class="ss">hello</span><span class="p" data-group-id="8952612466-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>There are a number of BIFs for type conversions.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="6013348659-1">(</span><span class="ss">hello</span><span class="p" data-group-id="6013348659-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="8952612466-2">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="8952612466-2">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="6013348659-2">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6013348659-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="8952612466-3">(</span><span class="p" data-group-id="8952612466-4">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="8952612466-4">&gt;&gt;</span><span class="p" data-group-id="8952612466-3">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="6013348659-3">(</span><span class="p" data-group-id="6013348659-4">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6013348659-4">&gt;&gt;</span><span class="p" data-group-id="6013348659-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="8952612466-5">(</span><span class="p" data-group-id="8952612466-6">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="8952612466-6">&gt;&gt;</span><span class="p" data-group-id="8952612466-5">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nf">binary_to_list</span><span class="p" data-group-id="6013348659-5">(</span><span class="p" data-group-id="6013348659-6">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="6013348659-6">&gt;&gt;</span><span class="p" data-group-id="6013348659-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nf">list_to_binary</span><span class="p" data-group-id="8952612466-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="8952612466-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8952612466-8">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="8952612466-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="8952612466-9">(</span><span class="mf">7.0</span><span class="p" data-group-id="8952612466-9">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nf">list_to_binary</span><span class="p" data-group-id="6013348659-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6013348659-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6013348659-8">&lt;&lt;</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="6013348659-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +6&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="6013348659-9">(</span><span class="mf">7.0</span><span class="p" data-group-id="6013348659-9">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;7.00000000000000000000e+00&quot;</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="nf">list_to_float</span><span class="p" data-group-id="8952612466-10">(</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="8952612466-10">)</span><span class="p">.</span><span class="w">
│ │ │ +7&gt; </span><span class="nf">list_to_float</span><span class="p" data-group-id="6013348659-10">(</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="6013348659-10">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">7.0</span><span class="gp unselectable">
│ │ │ -8&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="8952612466-11">(</span><span class="mi">77</span><span class="p" data-group-id="8952612466-11">)</span><span class="p">.</span><span class="w">
│ │ │ +8&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="6013348659-11">(</span><span class="mi">77</span><span class="p" data-group-id="6013348659-11">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;77&quot;</span><span class="gp unselectable">
│ │ │ -9&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="8952612466-12">(</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="8952612466-12">)</span><span class="p">.</span><span class="w">
│ │ │ +9&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="6013348659-12">(</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="6013348659-12">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">77</span><span class="gp unselectable">
│ │ │ -10&gt; </span><span class="nf">tuple_to_list</span><span class="p" data-group-id="8952612466-13">(</span><span class="p" data-group-id="8952612466-14">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8952612466-14">}</span><span class="p" data-group-id="8952612466-13">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8952612466-15">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8952612466-15">]</span><span class="gp unselectable">
│ │ │ -11&gt; </span><span class="nf">list_to_tuple</span><span class="p" data-group-id="8952612466-16">(</span><span class="p" data-group-id="8952612466-17">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8952612466-17">]</span><span class="p" data-group-id="8952612466-16">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8952612466-18">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8952612466-18">}</span><span class="gp unselectable">
│ │ │ -12&gt; </span><span class="nf">term_to_binary</span><span class="p" data-group-id="8952612466-19">(</span><span class="p" data-group-id="8952612466-20">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8952612466-20">}</span><span class="p" data-group-id="8952612466-19">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8952612466-21">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="8952612466-21">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -13&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="8952612466-22">(</span><span class="p" data-group-id="8952612466-23">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="8952612466-23">&gt;&gt;</span><span class="p" data-group-id="8952612466-22">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8952612466-24">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8952612466-24">}</span><span class="gp unselectable">
│ │ │ -14&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="8952612466-25">(</span><span class="p" data-group-id="8952612466-26">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="8952612466-26">&gt;&gt;</span><span class="p" data-group-id="8952612466-25">)</span><span class="p">.</span><span class="w">
│ │ │ +10&gt; </span><span class="nf">tuple_to_list</span><span class="p" data-group-id="6013348659-13">(</span><span class="p" data-group-id="6013348659-14">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6013348659-14">}</span><span class="p" data-group-id="6013348659-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6013348659-15">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6013348659-15">]</span><span class="gp unselectable">
│ │ │ +11&gt; </span><span class="nf">list_to_tuple</span><span class="p" data-group-id="6013348659-16">(</span><span class="p" data-group-id="6013348659-17">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6013348659-17">]</span><span class="p" data-group-id="6013348659-16">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6013348659-18">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6013348659-18">}</span><span class="gp unselectable">
│ │ │ +12&gt; </span><span class="nf">term_to_binary</span><span class="p" data-group-id="6013348659-19">(</span><span class="p" data-group-id="6013348659-20">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6013348659-20">}</span><span class="p" data-group-id="6013348659-19">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6013348659-21">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="6013348659-21">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +13&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="6013348659-22">(</span><span class="p" data-group-id="6013348659-23">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">97</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="6013348659-23">&gt;&gt;</span><span class="p" data-group-id="6013348659-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6013348659-24">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="6013348659-24">}</span><span class="gp unselectable">
│ │ │ +14&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="6013348659-25">(</span><span class="p" data-group-id="6013348659-26">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="6013348659-26">&gt;&gt;</span><span class="p" data-group-id="6013348659-25">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">77</span><span class="gp unselectable">
│ │ │ -15&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="8952612466-27">(</span><span class="mi">77</span><span class="p" data-group-id="8952612466-27">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8952612466-28">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="8952612466-28">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -16&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="8952612466-29">(</span><span class="mf">7.0</span><span class="p" data-group-id="8952612466-29">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8952612466-30">&lt;&lt;</span><span class="s">&quot;7.00000000000000000000e+00&quot;</span><span class="p" data-group-id="8952612466-30">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -17&gt; </span><span class="nf">binary_to_float</span><span class="p" data-group-id="8952612466-31">(</span><span class="p" data-group-id="8952612466-32">&lt;&lt;</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="8952612466-32">&gt;&gt;</span><span class="p" data-group-id="8952612466-31">)</span><span class="p">.</span><span class="w">
│ │ │ +15&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="6013348659-27">(</span><span class="mi">77</span><span class="p" data-group-id="6013348659-27">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6013348659-28">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="6013348659-28">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +16&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="6013348659-29">(</span><span class="mf">7.0</span><span class="p" data-group-id="6013348659-29">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6013348659-30">&lt;&lt;</span><span class="s">&quot;7.00000000000000000000e+00&quot;</span><span class="p" data-group-id="6013348659-30">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +17&gt; </span><span class="nf">binary_to_float</span><span class="p" data-group-id="6013348659-31">(</span><span class="p" data-group-id="6013348659-32">&lt;&lt;</span><span class="s">&quot;7.000e+00&quot;</span><span class="p" data-group-id="6013348659-32">&gt;&gt;</span><span class="p" data-group-id="6013348659-31">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">7.0</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="character_set.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/design_principles.html
│ │ │ @@ -152,135 +152,135 @@
│ │ │  the code for a process in a generic part (a behaviour module) and a specific
│ │ │  part (a <em>callback module</em>).</p><p>The behaviour module is part of Erlang/OTP. To implement a process such as a
│ │ │  supervisor, the user only needs to implement the callback module, which is to
│ │ │  export a pre-defined set of functions, the <em>callback functions</em>.</p><p>The following example illustrate how code can be divided into a generic and a
│ │ │  specific part. Consider the following code (written in plain Erlang) for a
│ │ │  simple server, which keeps track of a number of &quot;channels&quot;. Other processes can
│ │ │  allocate and free the channels by calling the functions <code class="inline">alloc/0</code> and <code class="inline">free/1</code>,
│ │ │ -respectively.</p><p><a href="" id="ch1"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0490815867-1">(</span><span class="ss">ch1</span><span class="p" data-group-id="0490815867-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0490815867-2">(</span><span class="p" data-group-id="0490815867-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0490815867-3">]</span><span class="p" data-group-id="0490815867-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0490815867-4">(</span><span class="p" data-group-id="0490815867-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0490815867-5">]</span><span class="p" data-group-id="0490815867-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0490815867-6">(</span><span class="p" data-group-id="0490815867-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0490815867-7">]</span><span class="p" data-group-id="0490815867-6">)</span><span class="p">.</span><span class="w">
│ │ │ +respectively.</p><p><a href="" id="ch1"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2856974911-1">(</span><span class="ss">ch1</span><span class="p" data-group-id="2856974911-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2856974911-2">(</span><span class="p" data-group-id="2856974911-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2856974911-3">]</span><span class="p" data-group-id="2856974911-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2856974911-4">(</span><span class="p" data-group-id="2856974911-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2856974911-5">]</span><span class="p" data-group-id="2856974911-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2856974911-6">(</span><span class="p" data-group-id="2856974911-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2856974911-7">]</span><span class="p" data-group-id="2856974911-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="0490815867-8">(</span><span class="p" data-group-id="0490815867-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="0490815867-9">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0490815867-10">[</span><span class="p" data-group-id="0490815867-10">]</span><span class="p" data-group-id="0490815867-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="2856974911-8">(</span><span class="p" data-group-id="2856974911-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="2856974911-9">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2856974911-10">[</span><span class="p" data-group-id="2856974911-10">]</span><span class="p" data-group-id="2856974911-9">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="0490815867-11">(</span><span class="p" data-group-id="0490815867-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0490815867-12">{</span><span class="nf">self</span><span class="p" data-group-id="0490815867-13">(</span><span class="p" data-group-id="0490815867-13">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="0490815867-12">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="2856974911-11">(</span><span class="p" data-group-id="2856974911-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2856974911-12">{</span><span class="nf">self</span><span class="p" data-group-id="2856974911-13">(</span><span class="p" data-group-id="2856974911-13">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="2856974911-12">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0490815867-14">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="0490815867-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2856974911-14">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="2856974911-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Res</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="0490815867-15">(</span><span class="n">Ch</span><span class="p" data-group-id="0490815867-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0490815867-16">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0490815867-16">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="2856974911-15">(</span><span class="n">Ch</span><span class="p" data-group-id="2856974911-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ch1</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2856974911-16">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="2856974911-16">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="0490815867-17">(</span><span class="p" data-group-id="0490815867-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="0490815867-18">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0490815867-19">(</span><span class="p" data-group-id="0490815867-19">)</span><span class="p" data-group-id="0490815867-18">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="0490815867-20">(</span><span class="p" data-group-id="0490815867-20">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="0490815867-21">(</span><span class="n">Chs</span><span class="p" data-group-id="0490815867-21">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="2856974911-17">(</span><span class="p" data-group-id="2856974911-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="2856974911-18">(</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2856974911-19">(</span><span class="p" data-group-id="2856974911-19">)</span><span class="p" data-group-id="2856974911-18">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="2856974911-20">(</span><span class="p" data-group-id="2856974911-20">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="2856974911-21">(</span><span class="n">Chs</span><span class="p" data-group-id="2856974911-21">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="0490815867-22">(</span><span class="n">Chs</span><span class="p" data-group-id="0490815867-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="2856974911-22">(</span><span class="n">Chs</span><span class="p" data-group-id="2856974911-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0490815867-23">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="0490815867-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0490815867-24">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="0490815867-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="0490815867-25">(</span><span class="n">Chs</span><span class="p" data-group-id="0490815867-25">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0490815867-26">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0490815867-26">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="0490815867-27">(</span><span class="n">Chs2</span><span class="p" data-group-id="0490815867-27">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0490815867-28">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0490815867-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="0490815867-29">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0490815867-29">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="0490815867-30">(</span><span class="n">Chs2</span><span class="p" data-group-id="0490815867-30">)</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The code for the server can be rewritten into a generic part <code class="inline">server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4087488237-1">(</span><span class="ss">server</span><span class="p" data-group-id="4087488237-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4087488237-2">(</span><span class="p" data-group-id="4087488237-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4087488237-3">]</span><span class="p" data-group-id="4087488237-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4087488237-4">(</span><span class="p" data-group-id="4087488237-5">[</span><span class="ss">call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="4087488237-5">]</span><span class="p" data-group-id="4087488237-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4087488237-6">(</span><span class="p" data-group-id="4087488237-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4087488237-7">]</span><span class="p" data-group-id="4087488237-6">)</span><span class="p">.</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2856974911-23">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="2856974911-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="2856974911-24">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="2856974911-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="2856974911-25">(</span><span class="n">Chs</span><span class="p" data-group-id="2856974911-25">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2856974911-26">{</span><span class="ss">ch1</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="2856974911-26">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="2856974911-27">(</span><span class="n">Chs2</span><span class="p" data-group-id="2856974911-27">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2856974911-28">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="2856974911-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="2856974911-29">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2856974911-29">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="2856974911-30">(</span><span class="n">Chs2</span><span class="p" data-group-id="2856974911-30">)</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>The code for the server can be rewritten into a generic part <code class="inline">server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1194019338-1">(</span><span class="ss">server</span><span class="p" data-group-id="1194019338-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1194019338-2">(</span><span class="p" data-group-id="1194019338-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1194019338-3">]</span><span class="p" data-group-id="1194019338-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1194019338-4">(</span><span class="p" data-group-id="1194019338-5">[</span><span class="ss">call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1194019338-5">]</span><span class="p" data-group-id="1194019338-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1194019338-6">(</span><span class="p" data-group-id="1194019338-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1194019338-7">]</span><span class="p" data-group-id="1194019338-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="4087488237-8">(</span><span class="n">Mod</span><span class="p" data-group-id="4087488237-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="4087488237-9">(</span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4087488237-10">[</span><span class="n">Mod</span><span class="p" data-group-id="4087488237-10">]</span><span class="p" data-group-id="4087488237-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="1194019338-8">(</span><span class="n">Mod</span><span class="p" data-group-id="1194019338-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="1194019338-9">(</span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1194019338-10">[</span><span class="n">Mod</span><span class="p" data-group-id="1194019338-10">]</span><span class="p" data-group-id="1194019338-9">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">call</span><span class="p" data-group-id="4087488237-11">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="4087488237-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4087488237-12">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4087488237-13">(</span><span class="p" data-group-id="4087488237-13">)</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="4087488237-12">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">call</span><span class="p" data-group-id="1194019338-11">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="1194019338-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1194019338-12">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1194019338-13">(</span><span class="p" data-group-id="1194019338-13">)</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="1194019338-12">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4087488237-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="4087488237-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1194019338-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="1194019338-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Res</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">cast</span><span class="p" data-group-id="4087488237-15">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="4087488237-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4087488237-16">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="4087488237-16">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">cast</span><span class="p" data-group-id="1194019338-15">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="1194019338-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Name</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1194019338-16">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="1194019338-16">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="4087488237-17">(</span><span class="n">Mod</span><span class="p" data-group-id="4087488237-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="4087488237-18">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4087488237-19">(</span><span class="p" data-group-id="4087488237-19">)</span><span class="p" data-group-id="4087488237-18">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">init</span><span class="p" data-group-id="4087488237-20">(</span><span class="p" data-group-id="4087488237-20">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="4087488237-21">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4087488237-21">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="1194019338-17">(</span><span class="n">Mod</span><span class="p" data-group-id="1194019338-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="1194019338-18">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1194019338-19">(</span><span class="p" data-group-id="1194019338-19">)</span><span class="p" data-group-id="1194019338-18">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">init</span><span class="p" data-group-id="1194019338-20">(</span><span class="p" data-group-id="1194019338-20">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="1194019338-21">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1194019338-21">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="4087488237-22">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4087488237-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="1194019338-22">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1194019338-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4087488237-23">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="4087488237-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="4087488237-24">{</span><span class="n">Res</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="4087488237-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_call</span><span class="p" data-group-id="4087488237-25">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4087488237-25">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4087488237-26">{</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="4087488237-26">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="4087488237-27">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="4087488237-27">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4087488237-28">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="4087488237-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">State2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_cast</span><span class="p" data-group-id="4087488237-29">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4087488237-29">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="4087488237-30">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="4087488237-30">)</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>And a callback module <code class="inline">ch2.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0749609229-1">(</span><span class="ss">ch2</span><span class="p" data-group-id="0749609229-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0749609229-2">(</span><span class="p" data-group-id="0749609229-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0749609229-3">]</span><span class="p" data-group-id="0749609229-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0749609229-4">(</span><span class="p" data-group-id="0749609229-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0749609229-5">]</span><span class="p" data-group-id="0749609229-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0749609229-6">(</span><span class="p" data-group-id="0749609229-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0749609229-7">]</span><span class="p" data-group-id="0749609229-6">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="0749609229-8">(</span><span class="p" data-group-id="0749609229-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="0749609229-9">(</span><span class="ss">ch2</span><span class="p" data-group-id="0749609229-9">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="0749609229-10">(</span><span class="p" data-group-id="0749609229-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="0749609229-11">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="0749609229-11">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="0749609229-12">(</span><span class="n">Ch</span><span class="p" data-group-id="0749609229-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="0749609229-13">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0749609229-14">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0749609229-14">}</span><span class="p" data-group-id="0749609229-13">)</span><span class="p">.</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1194019338-23">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="1194019338-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="1194019338-24">{</span><span class="n">Res</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="1194019338-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_call</span><span class="p" data-group-id="1194019338-25">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1194019338-25">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1194019338-26">{</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="1194019338-26">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="1194019338-27">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="1194019338-27">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1194019338-28">{</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="n">Req</span><span class="p" data-group-id="1194019338-28">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">State2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Mod</span><span class="p">:</span><span class="nf">handle_cast</span><span class="p" data-group-id="1194019338-29">(</span><span class="n">Req</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1194019338-29">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="1194019338-30">(</span><span class="n">Mod</span><span class="p">,</span><span class="w"> </span><span class="n">State2</span><span class="p" data-group-id="1194019338-30">)</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>And a callback module <code class="inline">ch2.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0143290429-1">(</span><span class="ss">ch2</span><span class="p" data-group-id="0143290429-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0143290429-2">(</span><span class="p" data-group-id="0143290429-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0143290429-3">]</span><span class="p" data-group-id="0143290429-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0143290429-4">(</span><span class="p" data-group-id="0143290429-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0143290429-5">]</span><span class="p" data-group-id="0143290429-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0143290429-6">(</span><span class="p" data-group-id="0143290429-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0143290429-7">]</span><span class="p" data-group-id="0143290429-6">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="0143290429-8">(</span><span class="p" data-group-id="0143290429-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="0143290429-9">(</span><span class="ss">ch2</span><span class="p" data-group-id="0143290429-9">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="0143290429-10">(</span><span class="p" data-group-id="0143290429-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="0143290429-11">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="0143290429-11">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="0143290429-12">(</span><span class="n">Ch</span><span class="p" data-group-id="0143290429-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="0143290429-13">(</span><span class="ss">ch2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0143290429-14">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0143290429-14">}</span><span class="p" data-group-id="0143290429-13">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="0749609229-15">(</span><span class="p" data-group-id="0749609229-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">channels</span><span class="p" data-group-id="0749609229-16">(</span><span class="p" data-group-id="0749609229-16">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="0143290429-15">(</span><span class="p" data-group-id="0143290429-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">channels</span><span class="p" data-group-id="0143290429-16">(</span><span class="p" data-group-id="0143290429-16">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="0749609229-17">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0749609229-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">alloc</span><span class="p" data-group-id="0749609229-18">(</span><span class="n">Chs</span><span class="p" data-group-id="0749609229-18">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; {Ch,Chs2}</span><span class="w">
│ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="0143290429-17">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0143290429-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">alloc</span><span class="p" data-group-id="0143290429-18">(</span><span class="n">Chs</span><span class="p" data-group-id="0143290429-18">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; {Ch,Chs2}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="0749609229-19">(</span><span class="p" data-group-id="0749609229-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0749609229-20">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0749609229-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">free</span><span class="p" data-group-id="0749609229-21">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0749609229-21">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; Chs2</span></code></pre><p>Notice the following:</p><ul><li>The code in <code class="inline">server</code> can be reused to build many different servers.</li><li>The server name, in this example the atom <code class="inline">ch2</code>, is hidden from the users of
│ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="0143290429-19">(</span><span class="p" data-group-id="0143290429-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="0143290429-20">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0143290429-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">free</span><span class="p" data-group-id="0143290429-21">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0143290429-21">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% =&gt; Chs2</span></code></pre><p>Notice the following:</p><ul><li>The code in <code class="inline">server</code> can be reused to build many different servers.</li><li>The server name, in this example the atom <code class="inline">ch2</code>, is hidden from the users of
│ │ │  the client functions. This means that the name can be changed without
│ │ │  affecting them.</li><li>The protocol (messages sent to and received from the server) is also hidden.
│ │ │  This is good programming practice and allows one to change the protocol
│ │ │  without changing the code using the interface functions.</li><li>The functionality of <code class="inline">server</code> can be extended without having to change <code class="inline">ch2</code>
│ │ │  or any other callback module.</li></ul><p>In <code class="inline">ch1.erl</code> and <code class="inline">ch2.erl</code> above, the implementation of <code class="inline">channels/0</code>, <code class="inline">alloc/1</code>,
│ │ │  and <code class="inline">free/2</code> has been intentionally left out, as it is not relevant to the
│ │ │  example. For completeness, one way to write these functions is given below. This
│ │ │  is an example only, a realistic implementation must be able to handle situations
│ │ │ -like running out of channels to allocate, and so on.</p><p><a href="" id="channels-implementation"></a></p><pre><code class="makeup erlang" translate="no"><span class="nf">channels</span><span class="p" data-group-id="2929163717-1">(</span><span class="p" data-group-id="2929163717-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="2929163717-2">{</span><span class="p">_</span><span class="n">Allocated</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2929163717-3">[</span><span class="p" data-group-id="2929163717-3">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="2929163717-4">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="2929163717-4">)</span><span class="p" data-group-id="2929163717-2">}</span><span class="p">.</span><span class="w">
│ │ │ +like running out of channels to allocate, and so on.</p><p><a href="" id="channels-implementation"></a></p><pre><code class="makeup erlang" translate="no"><span class="nf">channels</span><span class="p" data-group-id="7183751442-1">(</span><span class="p" data-group-id="7183751442-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="7183751442-2">{</span><span class="p">_</span><span class="n">Allocated</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7183751442-3">[</span><span class="p" data-group-id="7183751442-3">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="7183751442-4">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="7183751442-4">)</span><span class="p" data-group-id="7183751442-2">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="2929163717-5">(</span><span class="p" data-group-id="2929163717-6">{</span><span class="n">Allocated</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2929163717-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2929163717-7">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="p" data-group-id="2929163717-6">}</span><span class="p" data-group-id="2929163717-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="2929163717-8">{</span><span class="n">H</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2929163717-9">{</span><span class="p" data-group-id="2929163717-10">[</span><span class="n">H</span><span class="p">|</span><span class="n">Allocated</span><span class="p" data-group-id="2929163717-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="2929163717-9">}</span><span class="p" data-group-id="2929163717-8">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="7183751442-5">(</span><span class="p" data-group-id="7183751442-6">{</span><span class="n">Allocated</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7183751442-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7183751442-7">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">_</span><span class="n">Free</span><span class="p" data-group-id="7183751442-6">}</span><span class="p" data-group-id="7183751442-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="7183751442-8">{</span><span class="n">H</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7183751442-9">{</span><span class="p" data-group-id="7183751442-10">[</span><span class="n">H</span><span class="p">|</span><span class="n">Allocated</span><span class="p" data-group-id="7183751442-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7183751442-9">}</span><span class="p" data-group-id="7183751442-8">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="2929163717-11">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2929163717-12">{</span><span class="n">Alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Free</span><span class="p" data-group-id="2929163717-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Channels</span><span class="p" data-group-id="2929163717-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="2929163717-13">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="2929163717-13">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="7183751442-11">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7183751442-12">{</span><span class="n">Alloc</span><span class="p">,</span><span class="w"> </span><span class="n">Free</span><span class="p" data-group-id="7183751442-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Channels</span><span class="p" data-group-id="7183751442-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">member</span><span class="p" data-group-id="7183751442-13">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="7183751442-13">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │        </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="2929163717-14">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="2929163717-15">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="2929163717-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2929163717-16">[</span><span class="n">Ch</span><span class="p">|</span><span class="n">Free</span><span class="p" data-group-id="2929163717-16">]</span><span class="p" data-group-id="2929163717-14">}</span><span class="p">;</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="7183751442-14">{</span><span class="nc">lists</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="7183751442-15">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="7183751442-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7183751442-16">[</span><span class="n">Ch</span><span class="p">|</span><span class="n">Free</span><span class="p" data-group-id="7183751442-16">]</span><span class="p" data-group-id="7183751442-14">}</span><span class="p">;</span><span class="w">
│ │ │        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │           </span><span class="n">Channels</span><span class="w">
│ │ │     </span><span class="k">end</span><span class="p">.</span></code></pre><p>Code written without using behaviours can be more efficient, but the increased
│ │ │  efficiency is at the expense of generality. The ability to manage all
│ │ │  applications in the system in a consistent manner is important.</p><p>Using behaviours also makes it easier to read and understand code written by
│ │ │  other programmers. Improvised programming structures, while possibly more
│ │ │  efficient, are always more difficult to understand.</p><p>The <code class="inline">server</code> module corresponds, greatly simplified, to the Erlang/OTP behaviour
│ │ │  <code class="inline">gen_server</code>.</p><p>The standard Erlang/OTP behaviours are:</p><ul><li><p><a href="gen_server_concepts.html">gen_server</a></p><p>For implementing the server of a client-server relation</p></li><li><p><a href="statem.html">gen_statem</a></p><p>For implementing state machines</p></li><li><p><a href="events.html">gen_event</a></p><p>For implementing event handling functionality</p></li><li><p><a href="sup_princ.html">supervisor</a></p><p>For implementing a supervisor in a supervision tree</p></li></ul><p>The compiler understands the module attribute <code class="inline">-behaviour(Behaviour)</code> and issues
│ │ │ -warnings about missing callback functions, for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0788733358-1">(</span><span class="ss">chs3</span><span class="p" data-group-id="0788733358-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="0788733358-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="0788733358-2">)</span><span class="p">.</span><span class="w">
│ │ │ +warnings about missing callback functions, for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4348541440-1">(</span><span class="ss">chs3</span><span class="p" data-group-id="4348541440-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="4348541440-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="4348541440-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="0788733358-3">(</span><span class="ss">chs3</span><span class="p" data-group-id="0788733358-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="4348541440-3">(</span><span class="ss">chs3</span><span class="p" data-group-id="4348541440-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="o">/</span><span class="ss">chs3</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">10</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="ss">undefined</span><span class="w"> </span><span class="ss">call</span><span class="o">-</span><span class="ss">back</span><span class="w"> </span><span class="ss">function</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0788733358-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">chs3</span><span class="p" data-group-id="0788733358-4">}</span></code></pre><h2 id="applications" class="section-heading">
│ │ │ +</span><span class="p" data-group-id="4348541440-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">chs3</span><span class="p" data-group-id="4348541440-4">}</span></code></pre><h2 id="applications" class="section-heading">
│ │ │    <a href="#applications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Applications</span>
│ │ │  </h2>
│ │ │  <p>Erlang/OTP comes with a number of components, each implementing some specific
│ │ │  functionality. Components are with Erlang/OTP terminology called <em>applications</em>.
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/distributed.html
│ │ │ @@ -142,25 +142,25 @@
│ │ │  </h2>
│ │ │  <p>A <em>node</em> is an executing Erlang runtime system that has been given a name, using
│ │ │  the command-line flag <a href="../../erts-15.2.7.3/doc/html/erl_cmd.html#name"><code class="inline">-name</code></a> (long names) or
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erl_cmd.html#sname"><code class="inline">-sname</code></a> (short names).</p><p>The format of the node name is an atom <code class="inline">name@host</code>. <code class="inline">name</code> is the name given by
│ │ │  the user. <code class="inline">host</code> is the full host name if long names are used, or the first part
│ │ │  of the host name if short names are used. Function <a href="../../erts-15.2.7.3/doc/html/erlang.html#node/0"><code class="inline">node()</code></a>
│ │ │  returns the name of the node.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -name dilbert</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9374868099-1">(</span><span class="ss">dilbert@uab</span><span class="p">.</span><span class="ss">ericsson</span><span class="p">.</span><span class="ss">se</span><span class="p" data-group-id="9374868099-1">)</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="9374868099-2">(</span><span class="p" data-group-id="9374868099-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1565589975-1">(</span><span class="ss">dilbert@uab</span><span class="p">.</span><span class="ss">ericsson</span><span class="p">.</span><span class="ss">se</span><span class="p" data-group-id="1565589975-1">)</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">node</span><span class="p" data-group-id="1565589975-2">(</span><span class="p" data-group-id="1565589975-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">&#39;dilbert@uab.ericsson.se&#39;</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">% erl -sname dilbert</span><span class="gp unselectable">
│ │ │ -(dilbert@uab)1&gt; </span><span class="nf">node</span><span class="p" data-group-id="9374868099-3">(</span><span class="p" data-group-id="9374868099-3">)</span><span class="p">.</span><span class="w">
│ │ │ +(dilbert@uab)1&gt; </span><span class="nf">node</span><span class="p" data-group-id="1565589975-3">(</span><span class="p" data-group-id="1565589975-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">dilbert@uab</span></code></pre><p>The node name can also be given in runtime by calling <a href="../../lib/kernel-10.2.7.2/doc/html/net_kernel.html#start/1"><code class="inline">net_kernel:start/1</code></a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nf">node</span><span class="p" data-group-id="2756659276-1">(</span><span class="p" data-group-id="2756659276-1">)</span><span class="p">.</span><span class="w">
│ │ │ +1&gt; </span><span class="nf">node</span><span class="p" data-group-id="6722604143-1">(</span><span class="p" data-group-id="6722604143-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">nonode@nohost</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">net_kernel</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2756659276-2">(</span><span class="p" data-group-id="2756659276-3">[</span><span class="ss">dilbert</span><span class="p">,</span><span class="ss">shortnames</span><span class="p" data-group-id="2756659276-3">]</span><span class="p" data-group-id="2756659276-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2756659276-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.102</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="2756659276-4">}</span><span class="gp unselectable">
│ │ │ -(dilbert@uab)3&gt; </span><span class="nf">node</span><span class="p" data-group-id="2756659276-5">(</span><span class="p" data-group-id="2756659276-5">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nc">net_kernel</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="6722604143-2">(</span><span class="p" data-group-id="6722604143-3">[</span><span class="ss">dilbert</span><span class="p">,</span><span class="ss">shortnames</span><span class="p" data-group-id="6722604143-3">]</span><span class="p" data-group-id="6722604143-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6722604143-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.102</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="6722604143-4">}</span><span class="gp unselectable">
│ │ │ +(dilbert@uab)3&gt; </span><span class="nf">node</span><span class="p" data-group-id="6722604143-5">(</span><span class="p" data-group-id="6722604143-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">dilbert@uab</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>A node with a long node name cannot communicate with a node with a short node
│ │ │  name.</p></section><h2 id="node-connections" class="section-heading">
│ │ │    <a href="#node-connections" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Node Connections</span>
│ │ │  </h2>
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/distributed_applications.html
│ │ │ @@ -150,36 +150,36 @@
│ │ │  (within the time-out specified by <code class="inline">sync_nodes_timeout</code>).</li><li><p><code class="inline">sync_nodes_timeout = integer() | infinity</code> - Specifies how many milliseconds
│ │ │  to wait for the other nodes to start.</p></li></ul><p>When started, the node waits for all nodes specified by <code class="inline">sync_nodes_mandatory</code>
│ │ │  and <code class="inline">sync_nodes_optional</code> to come up. When all nodes are up, or when all
│ │ │  mandatory nodes are up and the time specified by <code class="inline">sync_nodes_timeout</code> has
│ │ │  elapsed, all applications start. If not all mandatory nodes are up, the node
│ │ │  terminates.</p><p><em>Example:</em></p><p>An application <code class="inline">myapp</code> is to run at the node <code class="inline">cp1@cave</code>. If this node goes down,
│ │ │  <code class="inline">myapp</code> is to be restarted at <code class="inline">cp2@cave</code> or <code class="inline">cp3@cave</code>. A system configuration
│ │ │ -file <code class="inline">cp1.config</code> for <code class="inline">cp1@cave</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7470072236-1">[</span><span class="p" data-group-id="7470072236-2">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="7470072236-3">[</span><span class="p" data-group-id="7470072236-4">{</span><span class="ss">distributed</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7470072236-5">[</span><span class="p" data-group-id="7470072236-6">{</span><span class="ss">myapp</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7470072236-7">[</span><span class="ss">cp1@cave</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7470072236-8">{</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="7470072236-8">}</span><span class="p" data-group-id="7470072236-7">]</span><span class="p" data-group-id="7470072236-6">}</span><span class="p" data-group-id="7470072236-5">]</span><span class="p" data-group-id="7470072236-4">}</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="7470072236-9">{</span><span class="ss">sync_nodes_mandatory</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7470072236-10">[</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="7470072236-10">]</span><span class="p" data-group-id="7470072236-9">}</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="7470072236-11">{</span><span class="ss">sync_nodes_timeout</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p" data-group-id="7470072236-11">}</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="7470072236-3">]</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7470072236-2">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7470072236-1">]</span><span class="p">.</span></code></pre><p>The system configuration files for <code class="inline">cp2@cave</code> and <code class="inline">cp3@cave</code> are identical,
│ │ │ +file <code class="inline">cp1.config</code> for <code class="inline">cp1@cave</code> can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0902107813-1">[</span><span class="p" data-group-id="0902107813-2">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="0902107813-3">[</span><span class="p" data-group-id="0902107813-4">{</span><span class="ss">distributed</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0902107813-5">[</span><span class="p" data-group-id="0902107813-6">{</span><span class="ss">myapp</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0902107813-7">[</span><span class="ss">cp1@cave</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0902107813-8">{</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="0902107813-8">}</span><span class="p" data-group-id="0902107813-7">]</span><span class="p" data-group-id="0902107813-6">}</span><span class="p" data-group-id="0902107813-5">]</span><span class="p" data-group-id="0902107813-4">}</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="0902107813-9">{</span><span class="ss">sync_nodes_mandatory</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0902107813-10">[</span><span class="ss">cp2@cave</span><span class="p">,</span><span class="w"> </span><span class="ss">cp3@cave</span><span class="p" data-group-id="0902107813-10">]</span><span class="p" data-group-id="0902107813-9">}</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="0902107813-11">{</span><span class="ss">sync_nodes_timeout</span><span class="p">,</span><span class="w"> </span><span class="mi">5000</span><span class="p" data-group-id="0902107813-11">}</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="0902107813-3">]</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="0902107813-2">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0902107813-1">]</span><span class="p">.</span></code></pre><p>The system configuration files for <code class="inline">cp2@cave</code> and <code class="inline">cp3@cave</code> are identical,
│ │ │  except for the list of mandatory nodes, which is to be <code class="inline">[cp1@cave, cp3@cave]</code>
│ │ │  for <code class="inline">cp2@cave</code> and <code class="inline">[cp1@cave, cp2@cave]</code> for <code class="inline">cp3@cave</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>All involved nodes must have the same value for <code class="inline">distributed</code> and
│ │ │  <code class="inline">sync_nodes_timeout</code>. Otherwise the system behavior is undefined.</p></section><h2 id="starting-and-stopping-distributed-applications" class="section-heading">
│ │ │    <a href="#starting-and-stopping-distributed-applications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting and Stopping Distributed Applications</span>
│ │ │  </h2>
│ │ │  <p>When all involved (mandatory) nodes have been started, the distributed
│ │ │  application can be started by calling <code class="inline">application:start(Application)</code> at <em>all
│ │ │  of these nodes.</em></p><p>A boot script (see <a href="release_structure.html">Releases</a>) can be used that
│ │ │  automatically starts the application.</p><p>The application is started at the first operational node that is listed in the
│ │ │  list of nodes in the <code class="inline">distributed</code> configuration parameter. The application is
│ │ │  started as usual. That is, an application master is created and calls the
│ │ │ -application callback function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="8274414212-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="8274414212-1">)</span></code></pre><p>Example:</p><p>Continuing the example from the previous section, the three nodes are started,
│ │ │ +application callback function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="8966666421-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="8966666421-1">)</span></code></pre><p>Example:</p><p>Continuing the example from the previous section, the three nodes are started,
│ │ │  specifying the system configuration file:</p><pre><code class="text">&gt; erl -sname cp1 -config cp1
│ │ │  &gt; erl -sname cp2 -config cp2
│ │ │  &gt; erl -sname cp3 -config cp3</code></pre><p>When all nodes are operational, <code class="inline">myapp</code> can be started. This is achieved by
│ │ │  calling <code class="inline">application:start(myapp)</code> at all three nodes. It is then started at
│ │ │  <code class="inline">cp1</code>, as shown in the following figure:</p><p><a href="" id="dist1"></a></p><p><img src="assets/dist1.gif" alt="Application myapp - Situation 1" title="Application myapp - Situation 1"/></p><p>Similarly, the application must be stopped by calling
│ │ │  <code class="inline">application:stop(Application)</code> at all involved nodes.</p><h2 id="failover" class="section-heading">
│ │ │    <a href="#failover" class="hover-link">
│ │ │ @@ -187,30 +187,30 @@
│ │ │    </a>
│ │ │    <span class="text">Failover</span>
│ │ │  </h2>
│ │ │  <p>If the node where the application is running goes down, the application is
│ │ │  restarted (after the specified time-out) at the first operational node that is
│ │ │  listed in the list of nodes in the <code class="inline">distributed</code> configuration parameter. This
│ │ │  is called a <em>failover</em>.</p><p>The application is started the normal way at the new node, that is, by the
│ │ │ -application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="2874439220-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="2874439220-1">)</span></code></pre><p>An exception is if the application has the <code class="inline">start_phases</code> key defined (see
│ │ │ +application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4100479554-1">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="4100479554-1">)</span></code></pre><p>An exception is if the application has the <code class="inline">start_phases</code> key defined (see
│ │ │  <a href="included_applications.html">Included Applications</a>). The application is then
│ │ │ -instead started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="9049145414-1">(</span><span class="p" data-group-id="9049145414-2">{</span><span class="ss">failover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="9049145414-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="9049145414-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the terminated node.</p><p><em>Example:</em></p><p>If <code class="inline">cp1</code> goes down, the system checks which one of the other nodes, <code class="inline">cp2</code> or
│ │ │ +instead started by calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5804742015-1">(</span><span class="p" data-group-id="5804742015-2">{</span><span class="ss">failover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="5804742015-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="5804742015-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the terminated node.</p><p><em>Example:</em></p><p>If <code class="inline">cp1</code> goes down, the system checks which one of the other nodes, <code class="inline">cp2</code> or
│ │ │  <code class="inline">cp3</code>, has the least number of running applications, but waits for 5 seconds for
│ │ │  <code class="inline">cp1</code> to restart. If <code class="inline">cp1</code> does not restart and <code class="inline">cp2</code> runs fewer applications
│ │ │  than <code class="inline">cp3</code>, <code class="inline">myapp</code> is restarted on <code class="inline">cp2</code>.</p><p><a href="" id="dist2"></a></p><p><img src="assets/dist2.gif" alt="Application myapp - Situation 2" title="Application myapp - Situation 2"/></p><p>Suppose now that <code class="inline">cp2</code> goes also down and does not restart within 5 seconds.
│ │ │  <code class="inline">myapp</code> is now restarted on <code class="inline">cp3</code>.</p><p><a href="" id="dist3"></a></p><p><img src="assets/dist3.gif" alt="Application myapp - Situation 3" title="Application myapp - Situation 3"/></p><h2 id="takeover" class="section-heading">
│ │ │    <a href="#takeover" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Takeover</span>
│ │ │  </h2>
│ │ │  <p>If a node is started, which has higher priority according to <code class="inline">distributed</code> than
│ │ │  the node where a distributed application is running, the application is
│ │ │  restarted at the new node and stopped at the old node. This is called a
│ │ │ -<em>takeover</em>.</p><p>The application is started by the application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5236070839-1">(</span><span class="p" data-group-id="5236070839-2">{</span><span class="ss">takeover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="5236070839-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="5236070839-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the old node.</p><p><em>Example:</em></p><p>If <code class="inline">myapp</code> is running at <code class="inline">cp3</code>, and if <code class="inline">cp2</code> now restarts, it does not restart
│ │ │ +<em>takeover</em>.</p><p>The application is started by the application master calling:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="8138820009-1">(</span><span class="p" data-group-id="8138820009-2">{</span><span class="ss">takeover</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="8138820009-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">StartArgs</span><span class="p" data-group-id="8138820009-1">)</span></code></pre><p>Here <code class="inline">Node</code> is the old node.</p><p><em>Example:</em></p><p>If <code class="inline">myapp</code> is running at <code class="inline">cp3</code>, and if <code class="inline">cp2</code> now restarts, it does not restart
│ │ │  <code class="inline">myapp</code>, as the order between the <code class="inline">cp2</code> and <code class="inline">cp3</code> nodes is undefined.</p><p><a href="" id="dist4"></a></p><p><img src="assets/dist4.gif" alt="Application myapp - Situation 4" title="Application myapp - Situation 4"/></p><p>However, if <code class="inline">cp1</code> also restarts, the function <a href="../../lib/kernel-10.2.7.2/doc/html/application.html#takeover/2"><code class="inline">application:takeover/2</code></a> moves
│ │ │  <code class="inline">myapp</code> to <code class="inline">cp1</code>, as <code class="inline">cp1</code> has a higher priority than <code class="inline">cp3</code> for this
│ │ │  application. In this case, <code class="inline">Module:start({takeover, cp3@cave}, StartArgs)</code> is
│ │ │  executed at <code class="inline">cp1</code> to start the application.</p><p><a href="" id="dist5"></a></p><p><img src="assets/dist5.gif" alt="Application myapp - Situation 5" title="Application myapp - Situation 5"/></p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/documentation.html
│ │ │ @@ -112,23 +112,23 @@
│ │ │        </a>
│ │ │  
│ │ │  
│ │ │      <span>Documentation</span>
│ │ │    </h1>
│ │ │  
│ │ │  <p>Documentation in Erlang is done through the <code class="inline">-moduledoc</code> and <code class="inline">-doc</code>
│ │ │ -<a href="modules.html#module-attributes">attributes</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5451346638-1">(</span><span class="ss">arith</span><span class="p" data-group-id="5451346638-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<a href="modules.html#module-attributes">attributes</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5586379257-1">(</span><span class="ss">arith</span><span class="p" data-group-id="5586379257-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │  A module for basic arithmetic.
│ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5451346638-2">(</span><span class="p" data-group-id="5451346638-3">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5451346638-3">]</span><span class="p" data-group-id="5451346638-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5586379257-2">(</span><span class="p" data-group-id="5586379257-3">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5586379257-3">]</span><span class="p" data-group-id="5586379257-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;Adds two numbers.&quot;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="5451346638-4">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5451346638-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The <code class="inline">-moduledoc</code> attribute has to be located before the first <code class="inline">-doc</code> attribute
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="5586379257-4">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5586379257-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The <code class="inline">-moduledoc</code> attribute has to be located before the first <code class="inline">-doc</code> attribute
│ │ │  or function declaration. It documents the overall purpose of the module.</p><p>The <code class="inline">-doc</code> attribute always precedes the <a href="ref_man_functions.html">function</a> or
│ │ │  <a href="modules.html#module-attributes">attribute</a> it documents. The
│ │ │  attributes that can be documented are
│ │ │  <a href="typespec.html#type-declarations-of-user-defined-types">user-defined types</a>
│ │ │  (<code class="inline">-type</code> and <code class="inline">-opaque</code>) and
│ │ │  <a href="modules.html#behaviour-module-attribute">behaviour module attributes</a>
│ │ │  (<code class="inline">-callback</code>).</p><p>By default the format used for documentation attributes is
│ │ │ @@ -140,55 +140,55 @@
│ │ │  <a href="modules.html#documentation-attributes">Documentation Attributes</a>.</p><p><code class="inline">-doc</code> attributes have been available since Erlang/OTP 27.</p><h2 id="documentation-metadata" class="section-heading">
│ │ │    <a href="#documentation-metadata" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Documentation metadata</span>
│ │ │  </h2>
│ │ │  <p>It is possible to add metadata to the documentation entry. You do this by adding
│ │ │ -a <code class="inline">-moduledoc</code> or <code class="inline">-doc</code> attribute with a map as argument. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9517382841-1">(</span><span class="ss">arith</span><span class="p" data-group-id="9517382841-1">)</span><span class="p">.</span><span class="w">
│ │ │ +a <code class="inline">-moduledoc</code> or <code class="inline">-doc</code> attribute with a map as argument. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3454694570-1">(</span><span class="ss">arith</span><span class="p" data-group-id="3454694570-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │  A module for basic arithmetic.
│ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="9517382841-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="9517382841-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="3454694570-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="3454694570-2">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9517382841-3">(</span><span class="p" data-group-id="9517382841-4">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9517382841-4">]</span><span class="p" data-group-id="9517382841-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3454694570-3">(</span><span class="p" data-group-id="3454694570-4">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3454694570-4">]</span><span class="p" data-group-id="3454694570-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;Adds two numbers.&quot;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="9517382841-5">(</span><span class="p" data-group-id="9517382841-6">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="9517382841-6">}</span><span class="p" data-group-id="9517382841-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="9517382841-7">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="9517382841-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The metadata is used by documentation tools to provide extra information to the
│ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="3454694570-5">(</span><span class="p" data-group-id="3454694570-6">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p" data-group-id="3454694570-6">}</span><span class="p" data-group-id="3454694570-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="3454694570-7">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="3454694570-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>The metadata is used by documentation tools to provide extra information to the
│ │ │  user. There can be multiple metadata documentation entries, in which case the
│ │ │  maps will be merged with the latest taking precedence if there are duplicate
│ │ │  keys. Example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;Adds two numbers.&quot;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="7324696745-1">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">author</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p" data-group-id="7324696745-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="7324696745-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="7324696745-2">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="7324696745-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="7324696745-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>This will result in a metadata entry of <code class="inline">#{since =&gt; &quot;2.0&quot;, author =&gt; &quot;Joe&quot;}</code>.</p><p>The keys and values in the metadata map can be any type, but it is recommended
│ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="4791642519-1">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;1.0&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">author</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p" data-group-id="4791642519-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="4791642519-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;2.0&quot;</span><span class="p" data-group-id="4791642519-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="4791642519-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="4791642519-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><p>This will result in a metadata entry of <code class="inline">#{since =&gt; &quot;2.0&quot;, author =&gt; &quot;Joe&quot;}</code>.</p><p>The keys and values in the metadata map can be any type, but it is recommended
│ │ │  that only <a href="data_types.html#atom">atoms</a> are used for keys and
│ │ │  <a href="data_types.html#string">strings</a> for the values.</p><h2 id="external-documentation-files" class="section-heading">
│ │ │    <a href="#external-documentation-files" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">External documentation files</span>
│ │ │  </h2>
│ │ │  <p>The <code class="inline">-moduledoc</code> and <code class="inline">-doc</code> can also be placed in external files. To do so use
│ │ │  <code class="inline">-doc {file, &quot;path/to/doc.md&quot;}</code> to point to the documentation. The path used is
│ │ │  relative to the file where the <code class="inline">-doc</code> attribute is located. For example:</p><pre><code class="markdown">%% doc/add.md
│ │ │  Adds two numbers.</code></pre><p>and</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% src/arith.erl</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="3629051495-1">(</span><span class="p" data-group-id="3629051495-2">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/add.md&quot;</span><span class="p" data-group-id="3629051495-2">}</span><span class="p" data-group-id="3629051495-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="3629051495-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="3629051495-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><h2 id="documenting-a-module" class="section-heading">
│ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="4601728507-1">(</span><span class="p" data-group-id="4601728507-2">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/add.md&quot;</span><span class="p" data-group-id="4601728507-2">}</span><span class="p" data-group-id="4601728507-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="4601728507-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="4601728507-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span></code></pre><h2 id="documenting-a-module" class="section-heading">
│ │ │    <a href="#documenting-a-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Documenting a module</span>
│ │ │  </h2>
│ │ │  <p>The module description should include details on how to use the API and examples
│ │ │  of the different functions working together. Here is a good place to use images
│ │ │  and other diagrams to better show the usage of the module. Instead of writing a
│ │ │  long text in the <code class="inline">moduledoc</code> attribute, it could be better to break it out into
│ │ │  an external page.</p><p>The <code class="inline">moduledoc</code> attribute should start with a short paragraph describing the
│ │ │ -module and then go into greater details. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0621838233-1">(</span><span class="ss">arith</span><span class="p" data-group-id="0621838233-1">)</span><span class="p">.</span><span class="w">
│ │ │ +module and then go into greater details. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0289007081-1">(</span><span class="ss">arith</span><span class="p" data-group-id="0289007081-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="s">&quot;
│ │ │     A module for basic arithmetic.
│ │ │  
│ │ │     This module can be used to add and subtract values. For example:
│ │ │  
│ │ │     ```erlang
│ │ │     1&gt; arith:substract(arith:add(2, 3), 1).
│ │ │ @@ -203,94 +203,94 @@
│ │ │  <p>There are three reserved metadata keys for <code class="inline">-moduledoc</code>:</p><ul><li><code class="inline">since</code> - Shows in which version of the application the module was added.
│ │ │  If this is added, all functions, types, and callbacks within will also receive
│ │ │  the same <code class="inline">since</code> value unless specified in the metadata of the function, type
│ │ │  or callback.</li><li><code class="inline">deprecated</code> - Shows a text in the documentation explaining that it is
│ │ │  deprecated and what to use instead.</li><li><code class="inline">format</code> - The format to use for all documentation in this module. The
│ │ │  default is <code class="inline">text/markdown</code>. It should be written using the
│ │ │  <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types">mime type</a>
│ │ │ -of the format.</li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="8866626797-1">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/arith.asciidoc&quot;</span><span class="p" data-group-id="8866626797-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="8866626797-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;0.1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">format</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;text/asciidoc&quot;</span><span class="p" data-group-id="8866626797-2">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="8866626797-3">#{</span><span class="ss">deprecated</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Use the Erlang arithmetic operators instead.&quot;</span><span class="p" data-group-id="8866626797-3">}</span><span class="p">.</span></code></pre><h2 id="documenting-functions-user-defined-types-and-callbacks" class="section-heading">
│ │ │ +of the format.</li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="7619271530-1">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;../doc/arith.asciidoc&quot;</span><span class="p" data-group-id="7619271530-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="7619271530-2">#{</span><span class="ss">since</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;0.1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">format</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;text/asciidoc&quot;</span><span class="p" data-group-id="7619271530-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">moduledoc</span><span class="w"> </span><span class="p" data-group-id="7619271530-3">#{</span><span class="ss">deprecated</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;Use the Erlang arithmetic operators instead.&quot;</span><span class="p" data-group-id="7619271530-3">}</span><span class="p">.</span></code></pre><h2 id="documenting-functions-user-defined-types-and-callbacks" class="section-heading">
│ │ │    <a href="#documenting-functions-user-defined-types-and-callbacks" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Documenting functions, user-defined types, and callbacks</span>
│ │ │  </h2>
│ │ │  <p>Functions, types, and callbacks can be documented using the <code class="inline">-doc</code> attribute.
│ │ │  Each entry should start with a short paragraph describing the purpose of entity,
│ │ │  and then go into greater detail in needed.</p><p>It is not recommended to include images or diagrams in this documentation as it
│ │ │  is used by IDEs and <a href="../../lib/stdlib-6.2.2.2/doc/html/c.html#h/1"><code class="inline">c:h/1</code></a> to show the documentation to the user.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │  A number that can be used by the arith module.
│ │ │  
│ │ │  We use a special number here so that we know
│ │ │  that this number comes from this module.
│ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3354094022-1">(</span><span class="p" data-group-id="3354094022-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3354094022-2">{</span><span class="ss">arith</span><span class="p">,</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">number</span><span class="p" data-group-id="3354094022-3">(</span><span class="p" data-group-id="3354094022-3">)</span><span class="p" data-group-id="3354094022-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="7690949916-1">(</span><span class="p" data-group-id="7690949916-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7690949916-2">{</span><span class="ss">arith</span><span class="p">,</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">number</span><span class="p" data-group-id="7690949916-3">(</span><span class="p" data-group-id="7690949916-3">)</span><span class="p" data-group-id="7690949916-2">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │  Adds two numbers.
│ │ │  
│ │ │  ### Example:
│ │ │  
│ │ │  ```
│ │ │  1&gt; arith:add(arith:number(1), arith:number(2)). {number, 3}
│ │ │  ```
│ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="3354094022-4">(</span><span class="nf">number</span><span class="p" data-group-id="3354094022-5">(</span><span class="p" data-group-id="3354094022-5">)</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3354094022-6">(</span><span class="p" data-group-id="3354094022-6">)</span><span class="p" data-group-id="3354094022-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3354094022-7">(</span><span class="p" data-group-id="3354094022-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="3354094022-8">(</span><span class="p" data-group-id="3354094022-9">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="p" data-group-id="3354094022-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3354094022-10">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="3354094022-10">}</span><span class="p" data-group-id="3354094022-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3354094022-11">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="3354094022-11">}</span><span class="p">.</span></code></pre><h3 id="doc-metadata" class="section-heading">
│ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="7690949916-4">(</span><span class="nf">number</span><span class="p" data-group-id="7690949916-5">(</span><span class="p" data-group-id="7690949916-5">)</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="7690949916-6">(</span><span class="p" data-group-id="7690949916-6">)</span><span class="p" data-group-id="7690949916-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="7690949916-7">(</span><span class="p" data-group-id="7690949916-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="7690949916-8">(</span><span class="p" data-group-id="7690949916-9">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="p" data-group-id="7690949916-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7690949916-10">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="7690949916-10">}</span><span class="p" data-group-id="7690949916-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7690949916-11">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="7690949916-11">}</span><span class="p">.</span></code></pre><h3 id="doc-metadata" class="section-heading">
│ │ │    <a href="#doc-metadata" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Doc metadata</span>
│ │ │  </h3>
│ │ │  <p>There are four reserved metadata keys for <code class="inline">-doc</code>:</p><ul><li><p><code class="inline">since =&gt; unicode:chardata()</code> - Shows which version of the application the
│ │ │  module was added.</p></li><li><p><code class="inline">deprecated =&gt; unicode:chardata()</code> - Shows a text in the documentation
│ │ │  explaining that it is deprecated and what to use instead. The compiler will
│ │ │  automatically insert this key if there is a <code class="inline">-deprecated</code> attribute marking a
│ │ │  function as deprecated.</p></li><li><p><code class="inline">equiv =&gt; unicode:chardata() | F/A | F(...)</code> - Notes that this function is equivalent to
│ │ │  another function in this module. The equivalence can be described using either
│ │ │ -<code class="inline">Func/Arity</code>, <code class="inline">Func(Args)</code> or a <a href="../../lib/stdlib-6.2.2.2/doc/html/unicode.html#t:chardata/0">unicode string</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="6472901758-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">add</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="6472901758-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="6472901758-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="6472901758-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="6472901758-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6472901758-4">[</span><span class="p" data-group-id="6472901758-4">]</span><span class="p" data-group-id="6472901758-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="6472901758-5">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="6472901758-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>or</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="9050579532-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="9050579532-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9050579532-3">[</span><span class="p" data-group-id="9050579532-3">]</span><span class="p" data-group-id="9050579532-2">)</span><span class="p" data-group-id="9050579532-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="9050579532-4">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="9050579532-5">(</span><span class="p" data-group-id="9050579532-5">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="9050579532-6">(</span><span class="p" data-group-id="9050579532-6">)</span><span class="p" data-group-id="9050579532-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="9050579532-7">(</span><span class="p" data-group-id="9050579532-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="9050579532-8">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="9050579532-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="9050579532-9">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9050579532-10">[</span><span class="p" data-group-id="9050579532-10">]</span><span class="p" data-group-id="9050579532-9">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="9050579532-11">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="9050579532-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The entry into the <a href="../../lib/kernel-10.2.7.2/doc/html/eep48_chapter.html">EEP-48</a> doc chunk metadata is
│ │ │ +<code class="inline">Func/Arity</code>, <code class="inline">Func(Args)</code> or a <a href="../../lib/stdlib-6.2.2.2/doc/html/unicode.html#t:chardata/0">unicode string</a>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="5235288513-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">add</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5235288513-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="5235288513-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5235288513-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="5235288513-3">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5235288513-4">[</span><span class="p" data-group-id="5235288513-4">]</span><span class="p" data-group-id="5235288513-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="5235288513-5">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="5235288513-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>or</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="p" data-group-id="8988946246-1">#{</span><span class="ss">equiv</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="8988946246-2">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8988946246-3">[</span><span class="p" data-group-id="8988946246-3">]</span><span class="p" data-group-id="8988946246-2">)</span><span class="p" data-group-id="8988946246-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="8988946246-4">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8988946246-5">(</span><span class="p" data-group-id="8988946246-5">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8988946246-6">(</span><span class="p" data-group-id="8988946246-6">)</span><span class="p" data-group-id="8988946246-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="8988946246-7">(</span><span class="p" data-group-id="8988946246-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="8988946246-8">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="8988946246-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">add</span><span class="p" data-group-id="8988946246-9">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8988946246-10">[</span><span class="p" data-group-id="8988946246-10">]</span><span class="p" data-group-id="8988946246-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="8988946246-11">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="8988946246-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The entry into the <a href="../../lib/kernel-10.2.7.2/doc/html/eep48_chapter.html">EEP-48</a> doc chunk metadata is
│ │ │  the value converted to a string.</p></li><li><p><code class="inline">exported =&gt; boolean()</code> - A <a href="../../erts-15.2.7.3/doc/html/erlang.html#t:boolean/0"><code class="inline">boolean/0</code></a> signifying if the entry is <code class="inline">exported</code>
│ │ │  or not. This value is automatically set by the compiler and should not be set
│ │ │  by the user.</p></li></ul><h3 id="doc-signatures" class="section-heading">
│ │ │    <a href="#doc-signatures" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Doc signatures</span>
│ │ │  </h3>
│ │ │  <p>The doc signature is a short text shown to describe the function and its arguments.
│ │ │  By default it is determined by looking at the names of the arguments in the
│ │ │ -<code class="inline">-spec</code> or function. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add</span><span class="p" data-group-id="7165648156-1">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="7165648156-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">-spec</code> or function. For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add</span><span class="p" data-group-id="5492948098-1">(</span><span class="n">One</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="p" data-group-id="5492948098-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">One</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Two</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">sub</span><span class="p" data-group-id="7165648156-2">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7165648156-3">(</span><span class="p" data-group-id="7165648156-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7165648156-4">(</span><span class="p" data-group-id="7165648156-4">)</span><span class="p" data-group-id="7165648156-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7165648156-5">(</span><span class="p" data-group-id="7165648156-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">sub</span><span class="p" data-group-id="7165648156-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7165648156-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span></code></pre><p>will have a signature of <code class="inline">add(One, Two)</code> and <code class="inline">sub(One, Two)</code>.</p><p>For types or callbacks, the signature is derived from the type or callback
│ │ │ -specification. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3922530638-1">(</span><span class="n">Value</span><span class="p" data-group-id="3922530638-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3922530638-2">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="3922530638-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">sub</span><span class="p" data-group-id="5492948098-2">(</span><span class="n">One</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="5492948098-3">(</span><span class="p" data-group-id="5492948098-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Two</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="5492948098-4">(</span><span class="p" data-group-id="5492948098-4">)</span><span class="p" data-group-id="5492948098-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="5492948098-5">(</span><span class="p" data-group-id="5492948098-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">sub</span><span class="p" data-group-id="5492948098-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5492948098-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span></code></pre><p>will have a signature of <code class="inline">add(One, Two)</code> and <code class="inline">sub(One, Two)</code>.</p><p>For types or callbacks, the signature is derived from the type or callback
│ │ │ +specification. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="6903834827-1">(</span><span class="n">Value</span><span class="p" data-group-id="6903834827-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="6903834827-2">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="6903834827-2">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% signature will be `number(Value)`</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3922530638-3">(</span><span class="p" data-group-id="3922530638-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3922530638-4">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3922530638-5">(</span><span class="p" data-group-id="3922530638-5">)</span><span class="p" data-group-id="3922530638-4">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="6903834827-3">(</span><span class="p" data-group-id="6903834827-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="6903834827-4">{</span><span class="ss">number</span><span class="p">,</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="6903834827-5">(</span><span class="p" data-group-id="6903834827-5">)</span><span class="p" data-group-id="6903834827-4">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% signature will be `number()`</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="3922530638-6">(</span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3922530638-7">(</span><span class="p" data-group-id="3922530638-7">)</span><span class="p" data-group-id="3922530638-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="6903834827-6">(</span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="6903834827-7">(</span><span class="p" data-group-id="6903834827-7">)</span><span class="p" data-group-id="6903834827-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% signature will be `increment(In)`</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="3922530638-8">(</span><span class="n">In</span><span class="p" data-group-id="3922530638-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="3922530638-9">(</span><span class="p" data-group-id="3922530638-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">increment</span><span class="p" data-group-id="6903834827-8">(</span><span class="n">In</span><span class="p" data-group-id="6903834827-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Out</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="6903834827-9">(</span><span class="p" data-group-id="6903834827-9">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% signature will be `increment(In)`</span></code></pre><p>If it is not possible to &quot;easily&quot; figure out a nice signature from the code, the
│ │ │  MFA syntax is used instead. For example: <code class="inline">add/2</code>, <code class="inline">number/1</code>, <code class="inline">increment/1</code></p><p>It is possible to supply a custom signature by placing it as the first line of the
│ │ │  <code class="inline">-doc</code> attribute. The provided signature must be in the form of a function
│ │ │  declaration up until the <code class="inline">-&gt;</code>. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;&quot;
│ │ │  add(One, Two)
│ │ │  
│ │ │  Adds two numbers.
│ │ │  &quot;&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="4128523772-1">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="4128523772-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p">.</span></code></pre><p>Will create the signature <code class="inline">add(One, Two)</code>. The signature will be removed from the
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="0792779261-1">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="0792779261-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p">.</span></code></pre><p>Will create the signature <code class="inline">add(One, Two)</code>. The signature will be removed from the
│ │ │  documentation string, so in the example above only the text <code class="inline">&quot;Adds two numbers&quot;</code>
│ │ │  will be part of the documentation. This works for functions, types, and
│ │ │  callbacks.</p><h2 id="links-in-markdown" class="section-heading">
│ │ │    <a href="#links-in-markdown" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Links in Markdown</span>
│ │ │ @@ -328,28 +328,28 @@
│ │ │  modules. That is, modules that should be used by other applications and modules
│ │ │  that should not. By default all modules in an application are visible, but by
│ │ │  setting <code class="inline">-moduledoc false.</code> specific modules can be hidden from being listed as
│ │ │  part of the available API.</p><p>An Erlang <a href="modules.html">module</a> consists of public and private functions and type
│ │ │  attributes. By default, all exported functions, exported types and callbacks are
│ │ │  considered visible and part of the modules public API. In addition, any
│ │ │  non-exported type that is referred to by any other visible type attribute is
│ │ │ -also visible, but not considered to be part of the public API. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6357502175-1">(</span><span class="p" data-group-id="6357502175-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6357502175-2">]</span><span class="p" data-group-id="6357502175-1">)</span><span class="p">.</span><span class="w">
│ │ │ +also visible, but not considered to be part of the public API. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4382636566-1">(</span><span class="p" data-group-id="4382636566-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="4382636566-2">]</span><span class="p" data-group-id="4382636566-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="6357502175-3">(</span><span class="p" data-group-id="6357502175-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="6357502175-4">(</span><span class="p" data-group-id="6357502175-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="6357502175-5">(</span><span class="p" data-group-id="6357502175-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">example</span><span class="p" data-group-id="6357502175-6">(</span><span class="p" data-group-id="6357502175-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>in the above code, the function <code class="inline">example/0</code> is exported and it referenced the
│ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="4382636566-3">(</span><span class="p" data-group-id="4382636566-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="4382636566-4">(</span><span class="p" data-group-id="4382636566-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="4382636566-5">(</span><span class="p" data-group-id="4382636566-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">example</span><span class="p" data-group-id="4382636566-6">(</span><span class="p" data-group-id="4382636566-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>in the above code, the function <code class="inline">example/0</code> is exported and it referenced the
│ │ │  un-exported type <code class="inline">private/0</code>. Therefore both <code class="inline">example/0</code> and <code class="inline">private/0</code> will be
│ │ │  marked as visible. The <code class="inline">private/0</code> type will have the metadata field <code class="inline">exported</code>
│ │ │  set to <code class="inline">false</code> to show that it is not part of the public API.</p><p>If you want to make a visible entity hidden you need to set the <code class="inline">-doc</code> attribute
│ │ │ -to <code class="inline">false</code>. Let us revisit our previous example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7777847972-1">(</span><span class="p" data-group-id="7777847972-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7777847972-2">]</span><span class="p" data-group-id="7777847972-1">)</span><span class="p">.</span><span class="w">
│ │ │ +to <code class="inline">false</code>. Let us revisit our previous example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5490140407-1">(</span><span class="p" data-group-id="5490140407-2">[</span><span class="ss">example</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5490140407-2">]</span><span class="p" data-group-id="5490140407-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="7777847972-3">(</span><span class="p" data-group-id="7777847972-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="7777847972-4">(</span><span class="p" data-group-id="7777847972-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="7777847972-5">(</span><span class="p" data-group-id="7777847972-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="5490140407-3">(</span><span class="p" data-group-id="5490140407-3">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">example</span><span class="p" data-group-id="5490140407-4">(</span><span class="p" data-group-id="5490140407-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">private</span><span class="p" data-group-id="5490140407-5">(</span><span class="p" data-group-id="5490140407-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="ss">false</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">example</span><span class="p" data-group-id="7777847972-6">(</span><span class="p" data-group-id="7777847972-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>The function <code class="inline">example/0</code> is exported but explicitly marked as hidden; therefore
│ │ │ +</span><span class="nf">example</span><span class="p" data-group-id="5490140407-6">(</span><span class="p" data-group-id="5490140407-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">one</span><span class="p">.</span></code></pre><p>The function <code class="inline">example/0</code> is exported but explicitly marked as hidden; therefore
│ │ │  both <code class="inline">example/0</code> and <code class="inline">private/0</code> will be hidden.</p><p>Any documentation added to an automatically hidden entity (non-exported function
│ │ │  or type) is ignored and will generate a warning. Such functions can be
│ │ │  documented using comments.</p><h2 id="compiling-and-getting-documentation" class="section-heading">
│ │ │    <a href="#compiling-and-getting-documentation" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Compiling and getting documentation</span>
│ │ │ @@ -375,21 +375,21 @@
│ │ │    <span class="text">Using ExDoc to generate HTML/ePub documentation</span>
│ │ │  </h2>
│ │ │  <p><a href="https://hexdocs.pm/ex_doc/">ExDoc</a> has built-in support to generate
│ │ │  documentation from Markdown. The simplest way is by using the
│ │ │  <a href="https://hexdocs.pm/rebar3_ex_doc">rebar3_ex_doc</a> plugin. To set up a
│ │ │  rebar3 project to use <a href="https://hexdocs.pm/ex_doc/">ExDoc</a> to generate
│ │ │  documentation add the following to your <code class="inline">rebar3.config</code>.</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Enable the plugin</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4780943723-1">{</span><span class="ss">plugins</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4780943723-2">[</span><span class="ss">rebar3_ex_doc</span><span class="p" data-group-id="4780943723-2">]</span><span class="p" data-group-id="4780943723-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7667882616-1">{</span><span class="ss">plugins</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7667882616-2">[</span><span class="ss">rebar3_ex_doc</span><span class="p" data-group-id="7667882616-2">]</span><span class="p" data-group-id="7667882616-1">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="p" data-group-id="4780943723-3">{</span><span class="ss">ex_doc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4780943723-4">[</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="4780943723-5">{</span><span class="ss">extras</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4780943723-6">[</span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="4780943723-6">]</span><span class="p" data-group-id="4780943723-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="4780943723-7">{</span><span class="ss">main</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="4780943723-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="4780943723-8">{</span><span class="ss">source_url</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;https://github.com/namespace/your_app&quot;</span><span class="p" data-group-id="4780943723-8">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4780943723-4">]</span><span class="p" data-group-id="4780943723-3">}</span><span class="p">.</span></code></pre><p>When configured you can run <code class="inline">rebar3 ex_doc</code> to generate the
│ │ │ +</span><span class="p" data-group-id="7667882616-3">{</span><span class="ss">ex_doc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7667882616-4">[</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7667882616-5">{</span><span class="ss">extras</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7667882616-6">[</span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="7667882616-6">]</span><span class="p" data-group-id="7667882616-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7667882616-7">{</span><span class="ss">main</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;README.md&quot;</span><span class="p" data-group-id="7667882616-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7667882616-8">{</span><span class="ss">source_url</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;https://github.com/namespace/your_app&quot;</span><span class="p" data-group-id="7667882616-8">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7667882616-4">]</span><span class="p" data-group-id="7667882616-3">}</span><span class="p">.</span></code></pre><p>When configured you can run <code class="inline">rebar3 ex_doc</code> to generate the
│ │ │  documentation to <code class="inline">doc/index.html</code>. For more details and options see
│ │ │  the <a href="https://hexdocs.pm/rebar3_ex_doc">rebar3_ex_doc</a> documentation.</p><p>You can also download the
│ │ │  <a href="https://github.com/elixir/ex_doc/releases/latest">release escript bundle</a> from
│ │ │  github and run it from the command line. The documentation for using the escript
│ │ │  is found by running <code class="inline">ex_doc --help</code>.</p><p>If you are writing documentation that will be using
│ │ │  <a href="https://hexdocs.pm/ex_doc/">ExDoc</a> to generate HTML/ePub it is highly
│ │ │  recommended to read its documentation.</p>
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/drivers.html
│ │ │ @@ -122,23 +122,23 @@
│ │ │    <span class="text">Drivers and Concurrency</span>
│ │ │  </h2>
│ │ │  <p>The runtime system always takes a lock before running any code in a driver.</p><p>By default, that lock is at the driver level, that is, if several ports have
│ │ │  been opened to the same driver, only code for one port at the same time can be
│ │ │  running.</p><p>A driver can be configured to have one lock for each port instead.</p><p>If a driver is used in a functional way (that is, holds no state, but only does
│ │ │  some heavy calculation and returns a result), several ports with registered
│ │ │  names can be opened beforehand, and the port to be used can be chosen based on
│ │ │ -the scheduler ID as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3101923691-1">(</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="3101923691-2">(</span><span class="p" data-group-id="3101923691-2">)</span><span class="p">,</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="3101923691-3">{</span><span class="ss">some_driver_01</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_02</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_03</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_04</span><span class="p">,</span><span class="w">
│ │ │ +the scheduler ID as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2337953274-1">(</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="2337953274-2">(</span><span class="p" data-group-id="2337953274-2">)</span><span class="p">,</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="2337953274-3">{</span><span class="ss">some_driver_01</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_02</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_03</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_04</span><span class="p">,</span><span class="w">
│ │ │  	 </span><span class="ss">some_driver_05</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_06</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_07</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_08</span><span class="p">,</span><span class="w">
│ │ │  	 </span><span class="ss">some_driver_09</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_10</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_11</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_12</span><span class="p">,</span><span class="w">
│ │ │ -	 </span><span class="ss">some_driver_13</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_14</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_15</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_16</span><span class="p" data-group-id="3101923691-3">}</span><span class="p" data-group-id="3101923691-1">)</span><span class="p">.</span><span class="w">
│ │ │ +	 </span><span class="ss">some_driver_13</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_14</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_15</span><span class="p">,</span><span class="w"> </span><span class="ss">some_driver_16</span><span class="p" data-group-id="2337953274-3">}</span><span class="p" data-group-id="2337953274-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">client_port</span><span class="p" data-group-id="3101923691-4">(</span><span class="p" data-group-id="3101923691-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">element</span><span class="p" data-group-id="3101923691-5">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="3101923691-6">(</span><span class="ss">scheduler_id</span><span class="p" data-group-id="3101923691-6">)</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="3101923691-7">(</span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="3101923691-8">(</span><span class="p" data-group-id="3101923691-8">)</span><span class="p" data-group-id="3101923691-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w">
│ │ │ -	    </span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="3101923691-9">(</span><span class="p" data-group-id="3101923691-9">)</span><span class="p" data-group-id="3101923691-5">)</span><span class="p">.</span></code></pre><p>As long as there are no more than 16 schedulers, there will never be any lock
│ │ │ +</span><span class="nf">client_port</span><span class="p" data-group-id="2337953274-4">(</span><span class="p" data-group-id="2337953274-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">element</span><span class="p" data-group-id="2337953274-5">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="2337953274-6">(</span><span class="ss">scheduler_id</span><span class="p" data-group-id="2337953274-6">)</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="nf">tuple_size</span><span class="p" data-group-id="2337953274-7">(</span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="2337953274-8">(</span><span class="p" data-group-id="2337953274-8">)</span><span class="p" data-group-id="2337953274-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="o">?</span><span class="n">PORT_NAMES</span><span class="p" data-group-id="2337953274-9">(</span><span class="p" data-group-id="2337953274-9">)</span><span class="p" data-group-id="2337953274-5">)</span><span class="p">.</span></code></pre><p>As long as there are no more than 16 schedulers, there will never be any lock
│ │ │  contention on the port lock for the driver.</p><h2 id="avoiding-copying-binaries-when-calling-a-driver" class="section-heading">
│ │ │    <a href="#avoiding-copying-binaries-when-calling-a-driver" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Avoiding Copying Binaries When Calling a Driver</span>
│ │ │  </h2>
│ │ │  <p>There are basically two ways to avoid copying a binary that is sent to a driver:</p><ul><li><p>If the <code class="inline">Data</code> argument for <a href="../../erts-15.2.7.3/doc/html/erlang.html#port_control/3"><code class="inline">port_control/3</code></a> is a
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/eff_guide_functions.html
│ │ │ @@ -122,67 +122,67 @@
│ │ │    <span class="text">Pattern Matching</span>
│ │ │  </h2>
│ │ │  <p>Pattern matching in function head as well as in <code class="inline">case</code> and <code class="inline">receive</code> clauses are
│ │ │  optimized by the compiler. With a few exceptions, there is nothing to gain by
│ │ │  rearranging clauses.</p><p>One exception is pattern matching of binaries. The compiler does not rearrange
│ │ │  clauses that match binaries. Placing the clause that matches against the empty
│ │ │  binary <em>last</em> is usually slightly faster than placing it <em>first</em>.</p><p>The following is a rather unnatural example to show another exception where
│ │ │ -rearranging clauses is beneficial:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map1</span><span class="p" data-group-id="1309246443-1">(</span><span class="ss">one</span><span class="p" data-group-id="1309246443-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="1309246443-2">(</span><span class="ss">two</span><span class="p" data-group-id="1309246443-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="1309246443-3">(</span><span class="ss">three</span><span class="p" data-group-id="1309246443-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="1309246443-4">(</span><span class="n">Int</span><span class="p" data-group-id="1309246443-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="1309246443-5">(</span><span class="n">Int</span><span class="p" data-group-id="1309246443-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="1309246443-6">(</span><span class="ss">four</span><span class="p" data-group-id="1309246443-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="1309246443-7">(</span><span class="ss">five</span><span class="p" data-group-id="1309246443-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map1</span><span class="p" data-group-id="1309246443-8">(</span><span class="ss">six</span><span class="p" data-group-id="1309246443-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>The problem is the clause with the variable <code class="inline">Int</code>. As a variable can match
│ │ │ +rearranging clauses is beneficial:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map1</span><span class="p" data-group-id="5645733491-1">(</span><span class="ss">one</span><span class="p" data-group-id="5645733491-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5645733491-2">(</span><span class="ss">two</span><span class="p" data-group-id="5645733491-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5645733491-3">(</span><span class="ss">three</span><span class="p" data-group-id="5645733491-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5645733491-4">(</span><span class="n">Int</span><span class="p" data-group-id="5645733491-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="5645733491-5">(</span><span class="n">Int</span><span class="p" data-group-id="5645733491-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5645733491-6">(</span><span class="ss">four</span><span class="p" data-group-id="5645733491-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5645733491-7">(</span><span class="ss">five</span><span class="p" data-group-id="5645733491-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map1</span><span class="p" data-group-id="5645733491-8">(</span><span class="ss">six</span><span class="p" data-group-id="5645733491-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>The problem is the clause with the variable <code class="inline">Int</code>. As a variable can match
│ │ │  anything, including the atoms <code class="inline">four</code>, <code class="inline">five</code>, and <code class="inline">six</code>, which the following
│ │ │  clauses also match, the compiler must generate suboptimal code that executes as
│ │ │  follows:</p><ul><li>First, the input value is compared to <code class="inline">one</code>, <code class="inline">two</code>, and <code class="inline">three</code> (using a
│ │ │  single instruction that does a binary search; thus, quite efficient even if
│ │ │  there are many values) to select which one of the first three clauses to
│ │ │  execute (if any).</li><li>If none of the first three clauses match, the fourth clause match as a
│ │ │  variable always matches.</li><li>If the guard test <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_integer/1"><code class="inline">is_integer(Int)</code></a> succeeds, the fourth
│ │ │  clause is executed.</li><li>If the guard test fails, the input value is compared to <code class="inline">four</code>, <code class="inline">five</code>, and
│ │ │  <code class="inline">six</code>, and the appropriate clause is selected. (There is a <code class="inline">function_clause</code>
│ │ │ -exception if none of the values matched.)</li></ul><p>Rewriting to either:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map2</span><span class="p" data-group-id="0254518284-1">(</span><span class="ss">one</span><span class="p" data-group-id="0254518284-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="0254518284-2">(</span><span class="ss">two</span><span class="p" data-group-id="0254518284-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="0254518284-3">(</span><span class="ss">three</span><span class="p" data-group-id="0254518284-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="0254518284-4">(</span><span class="ss">four</span><span class="p" data-group-id="0254518284-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="0254518284-5">(</span><span class="ss">five</span><span class="p" data-group-id="0254518284-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="0254518284-6">(</span><span class="ss">six</span><span class="p" data-group-id="0254518284-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map2</span><span class="p" data-group-id="0254518284-7">(</span><span class="n">Int</span><span class="p" data-group-id="0254518284-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="0254518284-8">(</span><span class="n">Int</span><span class="p" data-group-id="0254518284-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>or:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map3</span><span class="p" data-group-id="2240360092-1">(</span><span class="n">Int</span><span class="p" data-group-id="2240360092-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="2240360092-2">(</span><span class="n">Int</span><span class="p" data-group-id="2240360092-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="2240360092-3">(</span><span class="ss">one</span><span class="p" data-group-id="2240360092-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="2240360092-4">(</span><span class="ss">two</span><span class="p" data-group-id="2240360092-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="2240360092-5">(</span><span class="ss">three</span><span class="p" data-group-id="2240360092-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="2240360092-6">(</span><span class="ss">four</span><span class="p" data-group-id="2240360092-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="2240360092-7">(</span><span class="ss">five</span><span class="p" data-group-id="2240360092-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">atom_map3</span><span class="p" data-group-id="2240360092-8">(</span><span class="ss">six</span><span class="p" data-group-id="2240360092-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>gives slightly more efficient matching code.</p><p>Another example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs1</span><span class="p" data-group-id="7070447531-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7070447531-2">[</span><span class="p" data-group-id="7070447531-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="7070447531-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +exception if none of the values matched.)</li></ul><p>Rewriting to either:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map2</span><span class="p" data-group-id="8007178639-1">(</span><span class="ss">one</span><span class="p" data-group-id="8007178639-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="8007178639-2">(</span><span class="ss">two</span><span class="p" data-group-id="8007178639-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="8007178639-3">(</span><span class="ss">three</span><span class="p" data-group-id="8007178639-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="8007178639-4">(</span><span class="ss">four</span><span class="p" data-group-id="8007178639-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="8007178639-5">(</span><span class="ss">five</span><span class="p" data-group-id="8007178639-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="8007178639-6">(</span><span class="ss">six</span><span class="p" data-group-id="8007178639-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map2</span><span class="p" data-group-id="8007178639-7">(</span><span class="n">Int</span><span class="p" data-group-id="8007178639-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="8007178639-8">(</span><span class="n">Int</span><span class="p" data-group-id="8007178639-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>or:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">atom_map3</span><span class="p" data-group-id="9472820188-1">(</span><span class="n">Int</span><span class="p" data-group-id="9472820188-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="9472820188-2">(</span><span class="n">Int</span><span class="p" data-group-id="9472820188-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="9472820188-3">(</span><span class="ss">one</span><span class="p" data-group-id="9472820188-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="9472820188-4">(</span><span class="ss">two</span><span class="p" data-group-id="9472820188-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="9472820188-5">(</span><span class="ss">three</span><span class="p" data-group-id="9472820188-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="9472820188-6">(</span><span class="ss">four</span><span class="p" data-group-id="9472820188-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="9472820188-7">(</span><span class="ss">five</span><span class="p" data-group-id="9472820188-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">atom_map3</span><span class="p" data-group-id="9472820188-8">(</span><span class="ss">six</span><span class="p" data-group-id="9472820188-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span></code></pre><p>gives slightly more efficient matching code.</p><p>Another example:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs1</span><span class="p" data-group-id="5230702037-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230702037-2">[</span><span class="p" data-group-id="5230702037-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="5230702037-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Ys</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">map_pairs1</span><span class="p" data-group-id="7070447531-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7070447531-4">[</span><span class="p" data-group-id="7070447531-4">]</span><span class="p" data-group-id="7070447531-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">map_pairs1</span><span class="p" data-group-id="5230702037-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230702037-4">[</span><span class="p" data-group-id="5230702037-4">]</span><span class="p" data-group-id="5230702037-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Xs</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">map_pairs1</span><span class="p" data-group-id="7070447531-5">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7070447531-6">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="7070447531-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7070447531-7">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="7070447531-7">]</span><span class="p" data-group-id="7070447531-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7070447531-8">[</span><span class="n">Map</span><span class="p" data-group-id="7070447531-9">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7070447531-9">)</span><span class="p">|</span><span class="nf">map_pairs1</span><span class="p" data-group-id="7070447531-10">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="7070447531-10">)</span><span class="p" data-group-id="7070447531-8">]</span><span class="p">.</span></code></pre><p>The first argument is <em>not</em> a problem. It is variable, but it is a variable in
│ │ │ +</span><span class="nf">map_pairs1</span><span class="p" data-group-id="5230702037-5">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230702037-6">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="5230702037-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230702037-7">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="5230702037-7">]</span><span class="p" data-group-id="5230702037-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5230702037-8">[</span><span class="n">Map</span><span class="p" data-group-id="5230702037-9">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5230702037-9">)</span><span class="p">|</span><span class="nf">map_pairs1</span><span class="p" data-group-id="5230702037-10">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="5230702037-10">)</span><span class="p" data-group-id="5230702037-8">]</span><span class="p">.</span></code></pre><p>The first argument is <em>not</em> a problem. It is variable, but it is a variable in
│ │ │  all clauses. The problem is the variable in the second argument, <code class="inline">Xs</code>, in the
│ │ │  middle clause. Because the variable can match anything, the compiler is not
│ │ │  allowed to rearrange the clauses, but must generate code that matches them in
│ │ │  the order written.</p><p>If the function is rewritten as follows, the compiler is free to rearrange the
│ │ │ -clauses:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs2</span><span class="p" data-group-id="8383506285-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8383506285-2">[</span><span class="p" data-group-id="8383506285-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="8383506285-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +clauses:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">map_pairs2</span><span class="p" data-group-id="4408086993-1">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4408086993-2">[</span><span class="p" data-group-id="4408086993-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="4408086993-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Ys</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">map_pairs2</span><span class="p" data-group-id="8383506285-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8383506285-4">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="8383506285-4">]</span><span class="o">=</span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8383506285-5">[</span><span class="p" data-group-id="8383506285-5">]</span><span class="w"> </span><span class="p" data-group-id="8383506285-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">map_pairs2</span><span class="p" data-group-id="4408086993-3">(</span><span class="p">_</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4408086993-4">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="4408086993-4">]</span><span class="o">=</span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4408086993-5">[</span><span class="p" data-group-id="4408086993-5">]</span><span class="w"> </span><span class="p" data-group-id="4408086993-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Xs</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">map_pairs2</span><span class="p" data-group-id="8383506285-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8383506285-7">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="8383506285-7">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8383506285-8">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="8383506285-8">]</span><span class="p" data-group-id="8383506285-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8383506285-9">[</span><span class="n">Map</span><span class="p" data-group-id="8383506285-10">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8383506285-10">)</span><span class="p">|</span><span class="nf">map_pairs2</span><span class="p" data-group-id="8383506285-11">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="8383506285-11">)</span><span class="p" data-group-id="8383506285-9">]</span><span class="p">.</span></code></pre><p>The compiler will generate code similar to this:</p><p><strong>DO NOT (already done by the compiler)</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="6271206925-1">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs0</span><span class="p">,</span><span class="w"> </span><span class="n">Ys0</span><span class="p" data-group-id="6271206925-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">map_pairs2</span><span class="p" data-group-id="4408086993-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4408086993-7">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="4408086993-7">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4408086993-8">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="4408086993-8">]</span><span class="p" data-group-id="4408086993-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4408086993-9">[</span><span class="n">Map</span><span class="p" data-group-id="4408086993-10">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4408086993-10">)</span><span class="p">|</span><span class="nf">map_pairs2</span><span class="p" data-group-id="4408086993-11">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="4408086993-11">)</span><span class="p" data-group-id="4408086993-9">]</span><span class="p">.</span></code></pre><p>The compiler will generate code similar to this:</p><p><strong>DO NOT (already done by the compiler)</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="0445797195-1">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs0</span><span class="p">,</span><span class="w"> </span><span class="n">Ys0</span><span class="p" data-group-id="0445797195-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Xs0</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6271206925-2">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="6271206925-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="0445797195-2">[</span><span class="n">X</span><span class="p">|</span><span class="n">Xs</span><span class="p" data-group-id="0445797195-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  	    </span><span class="k">case</span><span class="w"> </span><span class="n">Ys0</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="6271206925-3">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="6271206925-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="p" data-group-id="6271206925-4">[</span><span class="n">Map</span><span class="p" data-group-id="6271206925-5">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6271206925-5">)</span><span class="p">|</span><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="6271206925-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="6271206925-6">)</span><span class="p" data-group-id="6271206925-4">]</span><span class="p">;</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="6271206925-7">[</span><span class="p" data-group-id="6271206925-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="0445797195-3">[</span><span class="n">Y</span><span class="p">|</span><span class="n">Ys</span><span class="p" data-group-id="0445797195-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="p" data-group-id="0445797195-4">[</span><span class="n">Map</span><span class="p" data-group-id="0445797195-5">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="0445797195-5">)</span><span class="p">|</span><span class="nf">explicit_map_pairs</span><span class="p" data-group-id="0445797195-6">(</span><span class="n">Map</span><span class="p">,</span><span class="w"> </span><span class="n">Xs</span><span class="p">,</span><span class="w"> </span><span class="n">Ys</span><span class="p" data-group-id="0445797195-6">)</span><span class="p" data-group-id="0445797195-4">]</span><span class="p">;</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="0445797195-7">[</span><span class="p" data-group-id="0445797195-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  		    </span><span class="n">Xs0</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6271206925-8">[</span><span class="p" data-group-id="6271206925-8">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="0445797195-8">[</span><span class="p" data-group-id="0445797195-8">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  	    </span><span class="n">Ys0</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>This is slightly faster for probably the most common case that the input lists
│ │ │  are not empty or very short. (Another advantage is that Dialyzer can deduce a
│ │ │  better type for the <code class="inline">Xs</code> variable.)</p><h2 id="function-calls" class="section-heading">
│ │ │    <a href="#function-calls" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/eff_guide_processes.html
│ │ │ @@ -119,45 +119,45 @@
│ │ │    <a href="#creating-an-erlang-process" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Creating an Erlang Process</span>
│ │ │  </h2>
│ │ │  <p>An Erlang process is lightweight compared to threads and processes in operating
│ │ │  systems.</p><p>A newly spawned Erlang process uses 327 words of memory. The size can be found
│ │ │ -as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="3827471438-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p">.</span><span class="mi">3</span><span class="p" data-group-id="3827471438-1">]</span><span class="w"> </span><span class="p" data-group-id="3827471438-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="3827471438-2">]</span><span class="w"> </span><span class="p" data-group-id="3827471438-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3827471438-3">]</span><span class="w"> </span><span class="p" data-group-id="3827471438-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="3827471438-4">]</span><span class="w"> </span><span class="p" data-group-id="3827471438-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3827471438-5">]</span><span class="w"> </span><span class="p" data-group-id="3827471438-6">[</span><span class="ss">jit</span><span class="p" data-group-id="3827471438-6">]</span><span class="w">
│ │ │ +as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="2939813136-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p">.</span><span class="mi">3</span><span class="p" data-group-id="2939813136-1">]</span><span class="w"> </span><span class="p" data-group-id="2939813136-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="2939813136-2">]</span><span class="w"> </span><span class="p" data-group-id="2939813136-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="2939813136-3">]</span><span class="w"> </span><span class="p" data-group-id="2939813136-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="2939813136-4">]</span><span class="w"> </span><span class="p" data-group-id="2939813136-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2939813136-5">]</span><span class="w"> </span><span class="p" data-group-id="2939813136-6">[</span><span class="ss">jit</span><span class="p" data-group-id="2939813136-6">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mf">2.3</span><span class="w"> </span><span class="p" data-group-id="3827471438-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="3827471438-8">(</span><span class="p" data-group-id="3827471438-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="3827471438-7">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3827471438-9">(</span><span class="p" data-group-id="3827471438-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="ss">infinity</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mf">2.3</span><span class="w"> </span><span class="p" data-group-id="2939813136-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="2939813136-8">(</span><span class="p" data-group-id="2939813136-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="2939813136-7">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="2939813136-9">(</span><span class="p" data-group-id="2939813136-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="ss">infinity</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">43.39164016</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="3827471438-10">{</span><span class="p">_</span><span class="p">,</span><span class="n">Bytes</span><span class="p" data-group-id="3827471438-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">process_info</span><span class="p" data-group-id="3827471438-11">(</span><span class="nf">spawn</span><span class="p" data-group-id="3827471438-12">(</span><span class="n">Fun</span><span class="p" data-group-id="3827471438-12">)</span><span class="p">,</span><span class="w"> </span><span class="nb">memory</span><span class="p" data-group-id="3827471438-11">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3827471438-13">{</span><span class="nb">memory</span><span class="p">,</span><span class="mi">2616</span><span class="p" data-group-id="3827471438-13">}</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="n">Bytes</span><span class="w"> </span><span class="ow">div</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="3827471438-14">(</span><span class="ss">wordsize</span><span class="p" data-group-id="3827471438-14">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="p" data-group-id="2939813136-10">{</span><span class="p">_</span><span class="p">,</span><span class="n">Bytes</span><span class="p" data-group-id="2939813136-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">process_info</span><span class="p" data-group-id="2939813136-11">(</span><span class="nf">spawn</span><span class="p" data-group-id="2939813136-12">(</span><span class="n">Fun</span><span class="p" data-group-id="2939813136-12">)</span><span class="p">,</span><span class="w"> </span><span class="nb">memory</span><span class="p" data-group-id="2939813136-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2939813136-13">{</span><span class="nb">memory</span><span class="p">,</span><span class="mi">2616</span><span class="p" data-group-id="2939813136-13">}</span><span class="gp unselectable">
│ │ │ +3&gt; </span><span class="n">Bytes</span><span class="w"> </span><span class="ow">div</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="2939813136-14">(</span><span class="ss">wordsize</span><span class="p" data-group-id="2939813136-14">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">327</span></code></pre><p>The size includes 233 words for the heap area (which includes the stack). The
│ │ │  garbage collector increases the heap as needed.</p><p>The main (outer) loop for a process <em>must</em> be tail-recursive. Otherwise, the
│ │ │ -stack grows until the process terminates.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="6026566971-1">(</span><span class="p" data-group-id="6026566971-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +stack grows until the process terminates.</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="4678816156-1">(</span><span class="p" data-group-id="4678816156-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │    </span><span class="k">receive</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="6026566971-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="6026566971-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="6026566971-3">(</span><span class="n">Msg</span><span class="p" data-group-id="6026566971-3">)</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="nf">loop</span><span class="p" data-group-id="6026566971-4">(</span><span class="p" data-group-id="6026566971-4">)</span><span class="p">;</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="6026566971-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="6026566971-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -          </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="6026566971-6">(</span><span class="n">Msg</span><span class="p" data-group-id="6026566971-6">)</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="4678816156-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4678816156-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="4678816156-3">(</span><span class="n">Msg</span><span class="p" data-group-id="4678816156-3">)</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="nf">loop</span><span class="p" data-group-id="4678816156-4">(</span><span class="p" data-group-id="4678816156-4">)</span><span class="p">;</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="4678816156-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="4678816156-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +          </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="4678816156-6">(</span><span class="n">Msg</span><span class="p" data-group-id="4678816156-6">)</span><span class="p">,</span><span class="w">
│ │ │            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Reply</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="nf">loop</span><span class="p" data-group-id="6026566971-7">(</span><span class="p" data-group-id="6026566971-7">)</span><span class="w">
│ │ │ +          </span><span class="nf">loop</span><span class="p" data-group-id="4678816156-7">(</span><span class="p" data-group-id="4678816156-7">)</span><span class="w">
│ │ │    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6026566971-8">(</span><span class="s">&quot;Message is processed</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6026566971-9">[</span><span class="p" data-group-id="6026566971-9">]</span><span class="p" data-group-id="6026566971-8">)</span><span class="p">.</span></code></pre><p>The call to <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> will never be executed, but a return address will
│ │ │ +  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4678816156-8">(</span><span class="s">&quot;Message is processed</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4678816156-9">[</span><span class="p" data-group-id="4678816156-9">]</span><span class="p" data-group-id="4678816156-8">)</span><span class="p">.</span></code></pre><p>The call to <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> will never be executed, but a return address will
│ │ │  still be pushed to the stack each time <code class="inline">loop/0</code> is called recursively. The
│ │ │ -correct tail-recursive version of the function looks as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="1619706486-1">(</span><span class="p" data-group-id="1619706486-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +correct tail-recursive version of the function looks as follows:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="3585213307-1">(</span><span class="p" data-group-id="3585213307-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │     </span><span class="k">receive</span><span class="w">
│ │ │ -      </span><span class="p" data-group-id="1619706486-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1619706486-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="1619706486-3">(</span><span class="n">Msg</span><span class="p" data-group-id="1619706486-3">)</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="nf">loop</span><span class="p" data-group-id="1619706486-4">(</span><span class="p" data-group-id="1619706486-4">)</span><span class="p">;</span><span class="w">
│ │ │ -      </span><span class="p" data-group-id="1619706486-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="1619706486-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -         </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="1619706486-6">(</span><span class="n">Msg</span><span class="p" data-group-id="1619706486-6">)</span><span class="p">,</span><span class="w">
│ │ │ +      </span><span class="p" data-group-id="3585213307-2">{</span><span class="ss">sys</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="3585213307-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +         </span><span class="nf">handle_sys_msg</span><span class="p" data-group-id="3585213307-3">(</span><span class="n">Msg</span><span class="p" data-group-id="3585213307-3">)</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="nf">loop</span><span class="p" data-group-id="3585213307-4">(</span><span class="p" data-group-id="3585213307-4">)</span><span class="p">;</span><span class="w">
│ │ │ +      </span><span class="p" data-group-id="3585213307-5">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="3585213307-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +         </span><span class="n">Reply</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="3585213307-6">(</span><span class="n">Msg</span><span class="p" data-group-id="3585213307-6">)</span><span class="p">,</span><span class="w">
│ │ │           </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Reply</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="nf">loop</span><span class="p" data-group-id="1619706486-7">(</span><span class="p" data-group-id="1619706486-7">)</span><span class="w">
│ │ │ +         </span><span class="nf">loop</span><span class="p" data-group-id="3585213307-7">(</span><span class="p" data-group-id="3585213307-7">)</span><span class="w">
│ │ │   </span><span class="k">end</span><span class="p">.</span></code></pre><h3 id="initial-heap-size" class="section-heading">
│ │ │    <a href="#initial-heap-size" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Initial Heap Size</span>
│ │ │  </h3>
│ │ │  <p>The default initial heap size of 233 words is quite conservative to support
│ │ │ @@ -189,30 +189,30 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Receiving messages</span>
│ │ │  </h2>
│ │ │  <p>The cost of receiving messages depends on how complicated the <code class="inline">receive</code>
│ │ │  expression is. A simple expression that matches any message is very cheap
│ │ │  because it retrieves the first message in the message queue:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="4651954458-1">(</span><span class="n">Message</span><span class="p" data-group-id="4651954458-1">)</span><span class="w">
│ │ │ +    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="2914667660-1">(</span><span class="n">Message</span><span class="p" data-group-id="2914667660-1">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>However, this is not always convenient: we can receive a message that we do not
│ │ │  know how to handle at this point, so it is common to only match the messages we
│ │ │  expect:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0453586125-1">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0453586125-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="0453586125-2">(</span><span class="n">Message</span><span class="p" data-group-id="0453586125-2">)</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5739716280-1">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5739716280-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5739716280-2">(</span><span class="n">Message</span><span class="p" data-group-id="5739716280-2">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>While this is convenient it means that the entire message queue must be searched
│ │ │  until it finds a matching message. This is very expensive for processes with
│ │ │  long message queues, so there is an optimization for the common case of
│ │ │ -sending a request and waiting for a response shortly after:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="2211942296-1">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="2211942296-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2211942296-2">{</span><span class="nf">self</span><span class="p" data-group-id="2211942296-3">(</span><span class="p" data-group-id="2211942296-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="2211942296-2">}</span><span class="p">,</span><span class="w">
│ │ │ +sending a request and waiting for a response shortly after:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="8300178096-1">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="8300178096-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8300178096-2">{</span><span class="nf">self</span><span class="p" data-group-id="8300178096-3">(</span><span class="p" data-group-id="8300178096-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="8300178096-2">}</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2211942296-4">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="2211942296-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="2211942296-5">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2211942296-6">[</span><span class="ss">flush</span><span class="p" data-group-id="2211942296-6">]</span><span class="p" data-group-id="2211942296-5">)</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="nf">handle_reply</span><span class="p" data-group-id="2211942296-7">(</span><span class="n">Reply</span><span class="p" data-group-id="2211942296-7">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2211942296-8">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2211942296-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nf">handle_error</span><span class="p" data-group-id="2211942296-9">(</span><span class="n">Reason</span><span class="p" data-group-id="2211942296-9">)</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8300178096-4">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="8300178096-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="8300178096-5">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8300178096-6">[</span><span class="ss">flush</span><span class="p" data-group-id="8300178096-6">]</span><span class="p" data-group-id="8300178096-5">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="nf">handle_reply</span><span class="p" data-group-id="8300178096-7">(</span><span class="n">Reply</span><span class="p" data-group-id="8300178096-7">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8300178096-8">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="8300178096-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nf">handle_error</span><span class="p" data-group-id="8300178096-9">(</span><span class="n">Reason</span><span class="p" data-group-id="8300178096-9">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p>Since the compiler knows that the reference created by
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#monitor/2"><code class="inline">monitor/2</code></a> cannot exist before the call (since it is a globally
│ │ │  unique identifier), and that the <code class="inline">receive</code> only matches messages that contain
│ │ │  said reference, it will tell the emulator to search only the messages that
│ │ │  arrived after the call to <a href="../../erts-15.2.7.3/doc/html/erlang.html#monitor/2"><code class="inline">monitor/2</code></a>.</p><p>The above is a simple example where one is but guaranteed that the optimization
│ │ │  will take, but what about more complicated code?</p><p><a href="" id="recv_opt_info"></a></p><h3 id="option-recv_opt_info" class="section-heading">
│ │ │    <a href="#option-recv_opt_info" class="hover-link">
│ │ │ @@ -228,101 +228,101 @@
│ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">200</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">NOT</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">clauses</span><span class="w"> </span><span class="ss">do</span><span class="w"> </span><span class="ow">not</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="ss">suitable</span><span class="w"> </span><span class="ss">reference</span><span class="w">
│ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">206</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">used</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">mark</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="ss">message</span><span class="w"> </span><span class="ss">queue</span><span class="w"> </span><span class="ss">position</span><span class="w">
│ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">208</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">clauses</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">created</span><span class="w"> </span><span class="ss">by</span><span class="w"> </span><span class="nb">monitor</span><span class="p">/</span><span class="mi">2</span><span class="w"> </span><span class="ss">at</span><span class="w"> </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">206</span><span class="w">
│ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">219</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">INFO</span><span class="p">:</span><span class="w"> </span><span class="ss">passing</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">created</span><span class="w"> </span><span class="ss">by</span><span class="w"> </span><span class="ss">make_ref</span><span class="p">/</span><span class="mi">0</span><span class="w"> </span><span class="ss">at</span><span class="w"> </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">218</span><span class="w">
│ │ │  </span><span class="ss">efficiency_guide</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">222</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="n">OPTIMIZED</span><span class="p">:</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">clauses</span><span class="w"> </span><span class="ss">match</span><span class="w"> </span><span class="ss">reference</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">function</span><span class="w"> </span><span class="ss">parameter</span><span class="w"> </span><span class="mi">1</span></code></pre><p>To make it clearer exactly what code the warnings refer to, the warnings in the
│ │ │  following examples are inserted as comments after the clause they refer to, for
│ │ │  example:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% DO</span><span class="w">
│ │ │ -</span><span class="nf">simple_receive</span><span class="p" data-group-id="5233039460-1">(</span><span class="p" data-group-id="5233039460-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">simple_receive</span><span class="p" data-group-id="2039487770-1">(</span><span class="p" data-group-id="2039487770-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="c1">%% efficiency_guide.erl:194: Warning: INFO: not a selective receive, this is always fast</span><span class="w">
│ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5233039460-2">(</span><span class="n">Message</span><span class="p" data-group-id="5233039460-2">)</span><span class="w">
│ │ │ +    </span><span class="n">Message</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="2039487770-2">(</span><span class="n">Message</span><span class="p" data-group-id="2039487770-2">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% DO NOT, unless Tag is known to be a suitable reference: see</span><span class="w">
│ │ │  </span><span class="c1">%% cross_function_receive/0 further down.</span><span class="w">
│ │ │ -</span><span class="nf">selective_receive</span><span class="p" data-group-id="5233039460-3">(</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5233039460-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">selective_receive</span><span class="p" data-group-id="2039487770-3">(</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2039487770-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="c1">%% efficiency_guide.erl:200: Warning: NOT OPTIMIZED: all clauses do not match a suitable reference</span><span class="w">
│ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5233039460-4">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5233039460-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5233039460-5">(</span><span class="n">Message</span><span class="p" data-group-id="5233039460-5">)</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2039487770-4">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2039487770-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="2039487770-5">(</span><span class="n">Message</span><span class="p" data-group-id="2039487770-5">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% DO</span><span class="w">
│ │ │ -</span><span class="nf">optimized_receive</span><span class="p" data-group-id="5233039460-6">(</span><span class="n">Process</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="5233039460-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">optimized_receive</span><span class="p" data-group-id="2039487770-6">(</span><span class="n">Process</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="2039487770-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="c1">%% efficiency_guide.erl:206: Warning: OPTIMIZED: reference used to mark a message queue position</span><span class="w">
│ │ │ -    </span><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="5233039460-7">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="5233039460-7">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5233039460-8">{</span><span class="nf">self</span><span class="p" data-group-id="5233039460-9">(</span><span class="p" data-group-id="5233039460-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="5233039460-8">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">MRef</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="2039487770-7">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">Process</span><span class="p" data-group-id="2039487770-7">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Process</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2039487770-8">{</span><span class="nf">self</span><span class="p" data-group-id="2039487770-9">(</span><span class="p" data-group-id="2039487770-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="2039487770-8">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="c1">%% efficiency_guide.erl:208: Warning: OPTIMIZED: matches reference created by monitor/2 at efficiency_guide.erl:206</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5233039460-10">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="5233039460-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="5233039460-11">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5233039460-12">[</span><span class="ss">flush</span><span class="p" data-group-id="5233039460-12">]</span><span class="p" data-group-id="5233039460-11">)</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="nf">handle_reply</span><span class="p" data-group-id="5233039460-13">(</span><span class="n">Reply</span><span class="p" data-group-id="5233039460-13">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5233039460-14">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="5233039460-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">handle_error</span><span class="p" data-group-id="5233039460-15">(</span><span class="n">Reason</span><span class="p" data-group-id="5233039460-15">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2039487770-10">{</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="p" data-group-id="2039487770-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">demonitor</span><span class="p" data-group-id="2039487770-11">(</span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2039487770-12">[</span><span class="ss">flush</span><span class="p" data-group-id="2039487770-12">]</span><span class="p" data-group-id="2039487770-11">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="nf">handle_reply</span><span class="p" data-group-id="2039487770-13">(</span><span class="n">Reply</span><span class="p" data-group-id="2039487770-13">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2039487770-14">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2039487770-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">handle_error</span><span class="p" data-group-id="2039487770-15">(</span><span class="n">Reason</span><span class="p" data-group-id="2039487770-15">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% DO</span><span class="w">
│ │ │ -</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="5233039460-16">(</span><span class="p" data-group-id="5233039460-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="2039487770-16">(</span><span class="p" data-group-id="2039487770-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% efficiency_guide.erl:218: Warning: OPTIMIZED: reference used to mark a message queue position</span><span class="w">
│ │ │ -    </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="5233039460-17">(</span><span class="p" data-group-id="5233039460-17">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Ref</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="2039487770-17">(</span><span class="p" data-group-id="2039487770-17">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="c1">%% efficiency_guide.erl:219: Warning: INFO: passing reference created by make_ref/0 at efficiency_guide.erl:218</span><span class="w">
│ │ │ -    </span><span class="nf">cross_function_receive</span><span class="p" data-group-id="5233039460-18">(</span><span class="n">Ref</span><span class="p" data-group-id="5233039460-18">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">cross_function_receive</span><span class="p" data-group-id="2039487770-18">(</span><span class="n">Ref</span><span class="p" data-group-id="2039487770-18">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="5233039460-19">(</span><span class="n">Ref</span><span class="p" data-group-id="5233039460-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">cross_function_receive</span><span class="p" data-group-id="2039487770-19">(</span><span class="n">Ref</span><span class="p" data-group-id="2039487770-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% efficiency_guide.erl:222: Warning: OPTIMIZED: all clauses match reference in function parameter 1</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5233039460-20">{</span><span class="n">Ref</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="5233039460-20">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="5233039460-21">(</span><span class="n">Message</span><span class="p" data-group-id="5233039460-21">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2039487770-20">{</span><span class="n">Ref</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2039487770-20">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_msg</span><span class="p" data-group-id="2039487770-21">(</span><span class="n">Message</span><span class="p" data-group-id="2039487770-21">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><h2 id="literal-pool" class="section-heading">
│ │ │    <a href="#literal-pool" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Literal Pool</span>
│ │ │  </h2>
│ │ │  <p>Constant Erlang terms (hereafter called <em>literals</em>) are kept in <em>literal pools</em>;
│ │ │  each loaded module has its own pool. The following function does not build the
│ │ │  tuple every time it is called (only to have it discarded the next time the
│ │ │  garbage collector was run), but the tuple is located in the module's literal
│ │ │ -pool:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">days_in_month</span><span class="p" data-group-id="1961550094-1">(</span><span class="n">M</span><span class="p" data-group-id="1961550094-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">element</span><span class="p" data-group-id="1961550094-2">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1961550094-3">{</span><span class="mi">31</span><span class="p">,</span><span class="mi">28</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p" data-group-id="1961550094-3">}</span><span class="p" data-group-id="1961550094-2">)</span><span class="p">.</span></code></pre><p>If a literal, or a term that contains a literal, is inserted into an Ets table,
│ │ │ +pool:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">days_in_month</span><span class="p" data-group-id="3203365937-1">(</span><span class="n">M</span><span class="p" data-group-id="3203365937-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">element</span><span class="p" data-group-id="3203365937-2">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3203365937-3">{</span><span class="mi">31</span><span class="p">,</span><span class="mi">28</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p">,</span><span class="mi">30</span><span class="p">,</span><span class="mi">31</span><span class="p" data-group-id="3203365937-3">}</span><span class="p" data-group-id="3203365937-2">)</span><span class="p">.</span></code></pre><p>If a literal, or a term that contains a literal, is inserted into an Ets table,
│ │ │  it is <em>copied</em>. The reason is that the module containing the literal can be
│ │ │  unloaded in the future.</p><p>When a literal is sent to another process, it is <em>not</em> copied. When a module
│ │ │  holding a literal is unloaded, the literal will be copied to the heap of all
│ │ │  processes that hold references to that literal.</p><p>There also exists a global literal pool that is managed by the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/persistent_term.html"><code class="inline">persistent_term</code></a> module.</p><p>By default, 1 GB of virtual address space is reserved for all literal pools (in
│ │ │  BEAM code and persistent terms). The amount of virtual address space reserved
│ │ │  for literals can be changed by using the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erts_alloc.html#MIscs"><code class="inline">+MIscs option</code></a> when starting the emulator.</p><p>Here is an example how the reserved virtual address space for literals can be
│ │ │  raised to 2 GB (2048 MB):</p><pre><code class="text">erl +MIscs 2048</code></pre><h2 id="loss-of-sharing" class="section-heading">
│ │ │    <a href="#loss-of-sharing" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Loss of Sharing</span>
│ │ │  </h2>
│ │ │ -<p>An Erlang term can have shared subterms. Here is a simple example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1185208804-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="1185208804-1">}</span></code></pre><p>Shared subterms are <em>not</em> preserved in the following cases:</p><ul><li>When a term is sent to another process</li><li>When a term is passed as the initial process arguments in the <code class="inline">spawn</code> call</li><li>When a term is stored in an Ets table</li></ul><p>That is an optimization. Most applications do not send messages with shared
│ │ │ -subterms.</p><p>The following example shows how a shared subterm can be created:</p><pre><code class="makeup erlang" translate="no"><span class="nf">kilo_byte</span><span class="p" data-group-id="7424579562-1">(</span><span class="p" data-group-id="7424579562-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="7424579562-2">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7424579562-3">[</span><span class="mi">42</span><span class="p" data-group-id="7424579562-3">]</span><span class="p" data-group-id="7424579562-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>An Erlang term can have shared subterms. Here is a simple example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4004405878-1">{</span><span class="n">SubTerm</span><span class="p">,</span><span class="w"> </span><span class="n">SubTerm</span><span class="p" data-group-id="4004405878-1">}</span></code></pre><p>Shared subterms are <em>not</em> preserved in the following cases:</p><ul><li>When a term is sent to another process</li><li>When a term is passed as the initial process arguments in the <code class="inline">spawn</code> call</li><li>When a term is stored in an Ets table</li></ul><p>That is an optimization. Most applications do not send messages with shared
│ │ │ +subterms.</p><p>The following example shows how a shared subterm can be created:</p><pre><code class="makeup erlang" translate="no"><span class="nf">kilo_byte</span><span class="p" data-group-id="5120745051-1">(</span><span class="p" data-group-id="5120745051-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="5120745051-2">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5120745051-3">[</span><span class="mi">42</span><span class="p" data-group-id="5120745051-3">]</span><span class="p" data-group-id="5120745051-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">kilo_byte</span><span class="p" data-group-id="7424579562-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7424579562-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">kilo_byte</span><span class="p" data-group-id="5120745051-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="5120745051-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">kilo_byte</span><span class="p" data-group-id="7424579562-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7424579562-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="7424579562-6">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7424579562-7">[</span><span class="n">Acc</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="7424579562-7">]</span><span class="p" data-group-id="7424579562-6">)</span><span class="p">.</span></code></pre><p><code class="inline">kilo_byte/1</code> creates a deep list. If <a href="../../erts-15.2.7.3/doc/html/erlang.html#list_to_binary/1"><code class="inline">list_to_binary/1</code></a>
│ │ │ +</span><span class="nf">kilo_byte</span><span class="p" data-group-id="5120745051-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="5120745051-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">kilo_byte</span><span class="p" data-group-id="5120745051-6">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5120745051-7">[</span><span class="n">Acc</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="5120745051-7">]</span><span class="p" data-group-id="5120745051-6">)</span><span class="p">.</span></code></pre><p><code class="inline">kilo_byte/1</code> creates a deep list. If <a href="../../erts-15.2.7.3/doc/html/erlang.html#list_to_binary/1"><code class="inline">list_to_binary/1</code></a>
│ │ │  is called, the deep list can be converted to a binary of 1024 bytes:</p><pre><code class="text">1&gt; byte_size(list_to_binary(efficiency_guide:kilo_byte())).
│ │ │  1024</code></pre><p>Using the <code class="inline">erts_debug:size/1</code> BIF, it can be seen that the deep list only
│ │ │ -requires 22 words of heap space:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="9202437260-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="9202437260-2">(</span><span class="p" data-group-id="9202437260-2">)</span><span class="p" data-group-id="9202437260-1">)</span><span class="p">.</span><span class="w">
│ │ │ +requires 22 words of heap space:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="4760043782-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="4760043782-2">(</span><span class="p" data-group-id="4760043782-2">)</span><span class="p" data-group-id="4760043782-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">22</span></code></pre><p>Using the <code class="inline">erts_debug:flat_size/1</code> BIF, the size of the deep list can be
│ │ │  calculated if sharing is ignored. It becomes the size of the list when it has
│ │ │ -been sent to another process or stored in an Ets table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="2602139019-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="2602139019-2">(</span><span class="p" data-group-id="2602139019-2">)</span><span class="p" data-group-id="2602139019-1">)</span><span class="p">.</span><span class="w">
│ │ │ +been sent to another process or stored in an Ets table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="1076845675-1">(</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="1076845675-2">(</span><span class="p" data-group-id="1076845675-2">)</span><span class="p" data-group-id="1076845675-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4094</span></code></pre><p>It can be verified that sharing will be lost if the data is inserted into an Ets
│ │ │ -table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="6690635258-1">(</span><span class="ss">tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6690635258-2">[</span><span class="p" data-group-id="6690635258-2">]</span><span class="p" data-group-id="6690635258-1">)</span><span class="p">.</span><span class="w">
│ │ │ +table:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="1378927779-1">(</span><span class="ss">tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1378927779-2">[</span><span class="p" data-group-id="1378927779-2">]</span><span class="p" data-group-id="1378927779-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Ref</span><span class="o">&lt;</span><span class="mf">0.1662103692</span><span class="p">.</span><span class="mf">2407923716.214181</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">ets</span><span class="p">:</span><span class="nf">insert</span><span class="p" data-group-id="6690635258-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6690635258-4">{</span><span class="ss">key</span><span class="p">,</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="6690635258-5">(</span><span class="p" data-group-id="6690635258-5">)</span><span class="p" data-group-id="6690635258-4">}</span><span class="p" data-group-id="6690635258-3">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">ets</span><span class="p">:</span><span class="nf">insert</span><span class="p" data-group-id="1378927779-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1378927779-4">{</span><span class="ss">key</span><span class="p">,</span><span class="nc">efficiency_guide</span><span class="p">:</span><span class="nf">kilo_byte</span><span class="p" data-group-id="1378927779-5">(</span><span class="p" data-group-id="1378927779-5">)</span><span class="p" data-group-id="1378927779-4">}</span><span class="p" data-group-id="1378927779-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="6690635258-6">(</span><span class="nf">element</span><span class="p" data-group-id="6690635258-7">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="6690635258-8">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="6690635258-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="6690635258-9">)</span><span class="p" data-group-id="6690635258-8">)</span><span class="p" data-group-id="6690635258-7">)</span><span class="p" data-group-id="6690635258-6">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">size</span><span class="p" data-group-id="1378927779-6">(</span><span class="nf">element</span><span class="p" data-group-id="1378927779-7">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="1378927779-8">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="1378927779-9">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="1378927779-9">)</span><span class="p" data-group-id="1378927779-8">)</span><span class="p" data-group-id="1378927779-7">)</span><span class="p" data-group-id="1378927779-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4094</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="6690635258-10">(</span><span class="nf">element</span><span class="p" data-group-id="6690635258-11">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="6690635258-12">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="6690635258-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="6690635258-13">)</span><span class="p" data-group-id="6690635258-12">)</span><span class="p" data-group-id="6690635258-11">)</span><span class="p" data-group-id="6690635258-10">)</span><span class="p">.</span><span class="w">
│ │ │ +7&gt; </span><span class="nc">erts_debug</span><span class="p">:</span><span class="nf">flat_size</span><span class="p" data-group-id="1378927779-10">(</span><span class="nf">element</span><span class="p" data-group-id="1378927779-11">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="nf">hd</span><span class="p" data-group-id="1378927779-12">(</span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="1378927779-13">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="ss">key</span><span class="p" data-group-id="1378927779-13">)</span><span class="p" data-group-id="1378927779-12">)</span><span class="p" data-group-id="1378927779-11">)</span><span class="p" data-group-id="1378927779-10">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4094</span></code></pre><p>When the data has passed through an Ets table, <code class="inline">erts_debug:size/1</code> and
│ │ │  <code class="inline">erts_debug:flat_size/1</code> return the same value. Sharing has been lost.</p><p>It is possible to build an <em>experimental</em> variant of the runtime system that
│ │ │  will preserve sharing when copying terms by giving the
│ │ │  <code class="inline">--enable-sharing-preserving</code> option to the <code class="inline">configure</code> script.</p><h2 id="smp-run-time-system" class="section-heading">
│ │ │    <a href="#smp-run-time-system" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/erl_interface.html
│ │ │ @@ -120,119 +120,119 @@
│ │ │  to read the port example in <a href="c_port.html">Ports</a> before reading this section.</p><h2 id="erlang-program" class="section-heading">
│ │ │    <a href="#erlang-program" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Erlang Program</span>
│ │ │  </h2>
│ │ │  <p>The following example shows an Erlang program communicating with a C program
│ │ │ -over a plain port with home made encoding:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6955172815-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="6955172815-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6955172815-2">(</span><span class="p" data-group-id="6955172815-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6955172815-3">]</span><span class="p" data-group-id="6955172815-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6955172815-4">(</span><span class="p" data-group-id="6955172815-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6955172815-5">]</span><span class="p" data-group-id="6955172815-4">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="6955172815-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="6955172815-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="6955172815-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6955172815-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="6955172815-8">]</span><span class="p" data-group-id="6955172815-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="6955172815-9">(</span><span class="p" data-group-id="6955172815-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +over a plain port with home made encoding:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2070419700-1">(</span><span class="ss">complex1</span><span class="p" data-group-id="2070419700-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2070419700-2">(</span><span class="p" data-group-id="2070419700-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2070419700-3">]</span><span class="p" data-group-id="2070419700-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2070419700-4">(</span><span class="p" data-group-id="2070419700-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2070419700-5">]</span><span class="p" data-group-id="2070419700-4">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="2070419700-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="2070419700-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="2070419700-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2070419700-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="2070419700-8">]</span><span class="p" data-group-id="2070419700-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="2070419700-9">(</span><span class="p" data-group-id="2070419700-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="6955172815-10">(</span><span class="n">X</span><span class="p" data-group-id="6955172815-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="6955172815-11">(</span><span class="p" data-group-id="6955172815-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6955172815-12">}</span><span class="p" data-group-id="6955172815-11">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="6955172815-13">(</span><span class="n">Y</span><span class="p" data-group-id="6955172815-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="6955172815-14">(</span><span class="p" data-group-id="6955172815-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6955172815-15">}</span><span class="p" data-group-id="6955172815-14">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="2070419700-10">(</span><span class="n">X</span><span class="p" data-group-id="2070419700-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="2070419700-11">(</span><span class="p" data-group-id="2070419700-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2070419700-12">}</span><span class="p" data-group-id="2070419700-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="2070419700-13">(</span><span class="n">Y</span><span class="p" data-group-id="2070419700-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="2070419700-14">(</span><span class="p" data-group-id="2070419700-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2070419700-15">}</span><span class="p" data-group-id="2070419700-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="6955172815-16">(</span><span class="n">Msg</span><span class="p" data-group-id="6955172815-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6955172815-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6955172815-18">(</span><span class="p" data-group-id="6955172815-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="6955172815-17">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="2070419700-16">(</span><span class="n">Msg</span><span class="p" data-group-id="2070419700-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2070419700-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2070419700-18">(</span><span class="p" data-group-id="2070419700-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2070419700-17">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6955172815-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6955172815-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="2070419700-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="2070419700-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="6955172815-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="6955172815-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="6955172815-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6955172815-22">(</span><span class="p" data-group-id="6955172815-22">)</span><span class="p" data-group-id="6955172815-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="6955172815-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6955172815-23">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="6955172815-24">(</span><span class="p" data-group-id="6955172815-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="6955172815-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6955172815-26">[</span><span class="p" data-group-id="6955172815-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6955172815-27">}</span><span class="p" data-group-id="6955172815-26">]</span><span class="p" data-group-id="6955172815-24">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="6955172815-28">(</span><span class="n">Port</span><span class="p" data-group-id="6955172815-28">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="2070419700-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="2070419700-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="2070419700-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2070419700-22">(</span><span class="p" data-group-id="2070419700-22">)</span><span class="p" data-group-id="2070419700-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="2070419700-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2070419700-23">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="2070419700-24">(</span><span class="p" data-group-id="2070419700-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="2070419700-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2070419700-26">[</span><span class="p" data-group-id="2070419700-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2070419700-27">}</span><span class="p" data-group-id="2070419700-26">]</span><span class="p" data-group-id="2070419700-24">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="2070419700-28">(</span><span class="n">Port</span><span class="p" data-group-id="2070419700-28">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="6955172815-29">(</span><span class="n">Port</span><span class="p" data-group-id="6955172815-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="2070419700-29">(</span><span class="n">Port</span><span class="p" data-group-id="2070419700-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6955172815-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="6955172815-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6955172815-31">{</span><span class="nf">self</span><span class="p" data-group-id="6955172815-32">(</span><span class="p" data-group-id="6955172815-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6955172815-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="6955172815-34">(</span><span class="n">Msg</span><span class="p" data-group-id="6955172815-34">)</span><span class="p" data-group-id="6955172815-33">}</span><span class="p" data-group-id="6955172815-31">}</span><span class="p">,</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="2070419700-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2070419700-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2070419700-31">{</span><span class="nf">self</span><span class="p" data-group-id="2070419700-32">(</span><span class="p" data-group-id="2070419700-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2070419700-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="2070419700-34">(</span><span class="n">Msg</span><span class="p" data-group-id="2070419700-34">)</span><span class="p" data-group-id="2070419700-33">}</span><span class="p" data-group-id="2070419700-31">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="6955172815-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6955172815-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6955172815-36">}</span><span class="p" data-group-id="6955172815-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6955172815-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="6955172815-38">(</span><span class="n">Data</span><span class="p" data-group-id="6955172815-38">)</span><span class="p" data-group-id="6955172815-37">}</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="2070419700-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2070419700-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2070419700-36">}</span><span class="p" data-group-id="2070419700-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2070419700-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="2070419700-38">(</span><span class="n">Data</span><span class="p" data-group-id="2070419700-38">)</span><span class="p" data-group-id="2070419700-37">}</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="6955172815-39">(</span><span class="n">Port</span><span class="p" data-group-id="6955172815-39">)</span><span class="p">;</span><span class="w">
│ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="2070419700-39">(</span><span class="n">Port</span><span class="p" data-group-id="2070419700-39">)</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6955172815-40">{</span><span class="nf">self</span><span class="p" data-group-id="6955172815-41">(</span><span class="p" data-group-id="6955172815-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="6955172815-40">}</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2070419700-40">{</span><span class="nf">self</span><span class="p" data-group-id="2070419700-41">(</span><span class="p" data-group-id="2070419700-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="2070419700-40">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="6955172815-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="6955172815-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="6955172815-43">(</span><span class="ss">normal</span><span class="p" data-group-id="6955172815-43">)</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="2070419700-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="2070419700-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="2070419700-43">(</span><span class="ss">normal</span><span class="p" data-group-id="2070419700-43">)</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6955172815-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="6955172815-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="6955172815-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="6955172815-45">)</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="2070419700-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2070419700-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="2070419700-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="2070419700-45">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="6955172815-46">(</span><span class="p" data-group-id="6955172815-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6955172815-47">}</span><span class="p" data-group-id="6955172815-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6955172815-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6955172815-48">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">encode</span><span class="p" data-group-id="6955172815-49">(</span><span class="p" data-group-id="6955172815-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6955172815-50">}</span><span class="p" data-group-id="6955172815-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6955172815-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6955172815-51">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="2070419700-46">(</span><span class="p" data-group-id="2070419700-47">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2070419700-47">}</span><span class="p" data-group-id="2070419700-46">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2070419700-48">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2070419700-48">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">encode</span><span class="p" data-group-id="2070419700-49">(</span><span class="p" data-group-id="2070419700-50">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2070419700-50">}</span><span class="p" data-group-id="2070419700-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2070419700-51">[</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2070419700-51">]</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">decode</span><span class="p" data-group-id="6955172815-52">(</span><span class="p" data-group-id="6955172815-53">[</span><span class="n">Int</span><span class="p" data-group-id="6955172815-53">]</span><span class="p" data-group-id="6955172815-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>There are two differences when using Erl_Interface on the C side compared to the
│ │ │ +</span><span class="nf">decode</span><span class="p" data-group-id="2070419700-52">(</span><span class="p" data-group-id="2070419700-53">[</span><span class="n">Int</span><span class="p" data-group-id="2070419700-53">]</span><span class="p" data-group-id="2070419700-52">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Int</span><span class="p">.</span></code></pre><p>There are two differences when using Erl_Interface on the C side compared to the
│ │ │  example in <a href="c_port.html">Ports</a>, using only the plain port:</p><ul><li>As Erl_Interface operates on the Erlang external term format, the port must be
│ │ │  set to use binaries.</li><li>Instead of inventing an encoding/decoding scheme, the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#term_to_binary/1"><code class="inline">term_to_binary/1</code></a> and
│ │ │ -<a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a> BIFs are to be used.</li></ul><p>That is:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="0545381034-1">(</span><span class="p" data-group-id="0545381034-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="0545381034-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0545381034-3">[</span><span class="p" data-group-id="0545381034-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="0545381034-4">}</span><span class="p" data-group-id="0545381034-3">]</span><span class="p" data-group-id="0545381034-1">)</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="4168584943-1">(</span><span class="p" data-group-id="4168584943-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="4168584943-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4168584943-3">[</span><span class="p" data-group-id="4168584943-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="4168584943-4">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="4168584943-3">]</span><span class="p" data-group-id="4168584943-1">)</span></code></pre><p>And:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0585320192-1">{</span><span class="nf">self</span><span class="p" data-group-id="0585320192-2">(</span><span class="p" data-group-id="0585320192-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0585320192-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="0585320192-4">(</span><span class="n">Msg</span><span class="p" data-group-id="0585320192-4">)</span><span class="p" data-group-id="0585320192-3">}</span><span class="p" data-group-id="0585320192-1">}</span><span class="p">,</span><span class="w">
│ │ │ +<a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a> BIFs are to be used.</li></ul><p>That is:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="0976770495-1">(</span><span class="p" data-group-id="0976770495-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="0976770495-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0976770495-3">[</span><span class="p" data-group-id="0976770495-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="0976770495-4">}</span><span class="p" data-group-id="0976770495-3">]</span><span class="p" data-group-id="0976770495-1">)</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open_port</span><span class="p" data-group-id="6400489891-1">(</span><span class="p" data-group-id="6400489891-2">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="6400489891-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6400489891-3">[</span><span class="p" data-group-id="6400489891-4">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6400489891-4">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="6400489891-3">]</span><span class="p" data-group-id="6400489891-1">)</span></code></pre><p>And:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0283493653-1">{</span><span class="nf">self</span><span class="p" data-group-id="0283493653-2">(</span><span class="p" data-group-id="0283493653-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0283493653-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">encode</span><span class="p" data-group-id="0283493653-4">(</span><span class="n">Msg</span><span class="p" data-group-id="0283493653-4">)</span><span class="p" data-group-id="0283493653-3">}</span><span class="p" data-group-id="0283493653-1">}</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0585320192-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0585320192-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0585320192-6">}</span><span class="p" data-group-id="0585320192-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0585320192-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="0585320192-8">(</span><span class="n">Data</span><span class="p" data-group-id="0585320192-8">)</span><span class="p" data-group-id="0585320192-7">}</span><span class="w">
│ │ │ -</span><span class="k">end</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3392066573-1">{</span><span class="nf">self</span><span class="p" data-group-id="3392066573-2">(</span><span class="p" data-group-id="3392066573-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3392066573-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="3392066573-4">(</span><span class="n">Msg</span><span class="p" data-group-id="3392066573-4">)</span><span class="p" data-group-id="3392066573-3">}</span><span class="p" data-group-id="3392066573-1">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="0283493653-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0283493653-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0283493653-6">}</span><span class="p" data-group-id="0283493653-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0283493653-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">decode</span><span class="p" data-group-id="0283493653-8">(</span><span class="n">Data</span><span class="p" data-group-id="0283493653-8">)</span><span class="p" data-group-id="0283493653-7">}</span><span class="w">
│ │ │ +</span><span class="k">end</span></code></pre><p>is replaced with:</p><pre><code class="makeup erlang" translate="no"><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5279608222-1">{</span><span class="nf">self</span><span class="p" data-group-id="5279608222-2">(</span><span class="p" data-group-id="5279608222-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5279608222-3">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="5279608222-4">(</span><span class="n">Msg</span><span class="p" data-group-id="5279608222-4">)</span><span class="p" data-group-id="5279608222-3">}</span><span class="p" data-group-id="5279608222-1">}</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="3392066573-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3392066573-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3392066573-6">}</span><span class="p" data-group-id="3392066573-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3392066573-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="3392066573-8">(</span><span class="n">Data</span><span class="p" data-group-id="3392066573-8">)</span><span class="p" data-group-id="3392066573-7">}</span><span class="w">
│ │ │ -</span><span class="k">end</span></code></pre><p>The resulting Erlang program is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6425242463-1">(</span><span class="ss">complex2</span><span class="p" data-group-id="6425242463-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6425242463-2">(</span><span class="p" data-group-id="6425242463-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6425242463-3">]</span><span class="p" data-group-id="6425242463-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6425242463-4">(</span><span class="p" data-group-id="6425242463-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6425242463-5">]</span><span class="p" data-group-id="6425242463-4">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="6425242463-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="6425242463-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="6425242463-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6425242463-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="6425242463-8">]</span><span class="p" data-group-id="6425242463-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="6425242463-9">(</span><span class="p" data-group-id="6425242463-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5279608222-5">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5279608222-6">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5279608222-6">}</span><span class="p" data-group-id="5279608222-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5279608222-7">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="5279608222-8">(</span><span class="n">Data</span><span class="p" data-group-id="5279608222-8">)</span><span class="p" data-group-id="5279608222-7">}</span><span class="w">
│ │ │ +</span><span class="k">end</span></code></pre><p>The resulting Erlang program is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2197675230-1">(</span><span class="ss">complex2</span><span class="p" data-group-id="2197675230-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2197675230-2">(</span><span class="p" data-group-id="2197675230-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2197675230-3">]</span><span class="p" data-group-id="2197675230-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2197675230-4">(</span><span class="p" data-group-id="2197675230-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2197675230-5">]</span><span class="p" data-group-id="2197675230-4">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="2197675230-6">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="2197675230-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="2197675230-7">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2197675230-8">[</span><span class="n">ExtPrg</span><span class="p" data-group-id="2197675230-8">]</span><span class="p" data-group-id="2197675230-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="2197675230-9">(</span><span class="p" data-group-id="2197675230-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">stop</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="6425242463-10">(</span><span class="n">X</span><span class="p" data-group-id="6425242463-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="6425242463-11">(</span><span class="p" data-group-id="6425242463-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6425242463-12">}</span><span class="p" data-group-id="6425242463-11">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="6425242463-13">(</span><span class="n">Y</span><span class="p" data-group-id="6425242463-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">call_port</span><span class="p" data-group-id="6425242463-14">(</span><span class="p" data-group-id="6425242463-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6425242463-15">}</span><span class="p" data-group-id="6425242463-14">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="2197675230-10">(</span><span class="n">X</span><span class="p" data-group-id="2197675230-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="2197675230-11">(</span><span class="p" data-group-id="2197675230-12">{</span><span class="ss">foo</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2197675230-12">}</span><span class="p" data-group-id="2197675230-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="2197675230-13">(</span><span class="n">Y</span><span class="p" data-group-id="2197675230-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">call_port</span><span class="p" data-group-id="2197675230-14">(</span><span class="p" data-group-id="2197675230-15">{</span><span class="ss">bar</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2197675230-15">}</span><span class="p" data-group-id="2197675230-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">call_port</span><span class="p" data-group-id="6425242463-16">(</span><span class="n">Msg</span><span class="p" data-group-id="6425242463-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6425242463-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6425242463-18">(</span><span class="p" data-group-id="6425242463-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="6425242463-17">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">call_port</span><span class="p" data-group-id="2197675230-16">(</span><span class="n">Msg</span><span class="p" data-group-id="2197675230-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">complex</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2197675230-17">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2197675230-18">(</span><span class="p" data-group-id="2197675230-18">)</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2197675230-17">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6425242463-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6425242463-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="2197675230-19">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="2197675230-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  	    </span><span class="n">Result</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="6425242463-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="6425242463-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="6425242463-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6425242463-22">(</span><span class="p" data-group-id="6425242463-22">)</span><span class="p" data-group-id="6425242463-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="6425242463-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6425242463-23">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="6425242463-24">(</span><span class="p" data-group-id="6425242463-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="6425242463-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6425242463-26">[</span><span class="p" data-group-id="6425242463-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6425242463-27">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="6425242463-26">]</span><span class="p" data-group-id="6425242463-24">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="6425242463-28">(</span><span class="n">Port</span><span class="p" data-group-id="6425242463-28">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="2197675230-20">(</span><span class="n">ExtPrg</span><span class="p" data-group-id="2197675230-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="2197675230-21">(</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2197675230-22">(</span><span class="p" data-group-id="2197675230-22">)</span><span class="p" data-group-id="2197675230-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="2197675230-23">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2197675230-23">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="2197675230-24">(</span><span class="p" data-group-id="2197675230-25">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="n">ExtPrg</span><span class="p" data-group-id="2197675230-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2197675230-26">[</span><span class="p" data-group-id="2197675230-27">{</span><span class="ss">packet</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2197675230-27">}</span><span class="p">,</span><span class="w"> </span><span class="ss">binary</span><span class="p" data-group-id="2197675230-26">]</span><span class="p" data-group-id="2197675230-24">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="2197675230-28">(</span><span class="n">Port</span><span class="p" data-group-id="2197675230-28">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="6425242463-29">(</span><span class="n">Port</span><span class="p" data-group-id="6425242463-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="2197675230-29">(</span><span class="n">Port</span><span class="p" data-group-id="2197675230-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6425242463-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="6425242463-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6425242463-31">{</span><span class="nf">self</span><span class="p" data-group-id="6425242463-32">(</span><span class="p" data-group-id="6425242463-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6425242463-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="6425242463-34">(</span><span class="n">Msg</span><span class="p" data-group-id="6425242463-34">)</span><span class="p" data-group-id="6425242463-33">}</span><span class="p" data-group-id="6425242463-31">}</span><span class="p">,</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="2197675230-30">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="n">Caller</span><span class="p">,</span><span class="w"> </span><span class="n">Msg</span><span class="p" data-group-id="2197675230-30">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2197675230-31">{</span><span class="nf">self</span><span class="p" data-group-id="2197675230-32">(</span><span class="p" data-group-id="2197675230-32">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2197675230-33">{</span><span class="ss">command</span><span class="p">,</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="2197675230-34">(</span><span class="n">Msg</span><span class="p" data-group-id="2197675230-34">)</span><span class="p" data-group-id="2197675230-33">}</span><span class="p" data-group-id="2197675230-31">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="6425242463-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6425242463-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6425242463-36">}</span><span class="p" data-group-id="6425242463-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6425242463-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="6425242463-38">(</span><span class="n">Data</span><span class="p" data-group-id="6425242463-38">)</span><span class="p" data-group-id="6425242463-37">}</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="2197675230-35">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2197675230-36">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2197675230-36">}</span><span class="p" data-group-id="2197675230-35">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="n">Caller</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2197675230-37">{</span><span class="ss">complex</span><span class="p">,</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="2197675230-38">(</span><span class="n">Data</span><span class="p" data-group-id="2197675230-38">)</span><span class="p" data-group-id="2197675230-37">}</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -	    </span><span class="nf">loop</span><span class="p" data-group-id="6425242463-39">(</span><span class="n">Port</span><span class="p" data-group-id="6425242463-39">)</span><span class="p">;</span><span class="w">
│ │ │ +	    </span><span class="nf">loop</span><span class="p" data-group-id="2197675230-39">(</span><span class="n">Port</span><span class="p" data-group-id="2197675230-39">)</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">stop</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6425242463-40">{</span><span class="nf">self</span><span class="p" data-group-id="6425242463-41">(</span><span class="p" data-group-id="6425242463-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="6425242463-40">}</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="n">Port</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2197675230-40">{</span><span class="nf">self</span><span class="p" data-group-id="2197675230-41">(</span><span class="p" data-group-id="2197675230-41">)</span><span class="p">,</span><span class="w"> </span><span class="ss">close</span><span class="p" data-group-id="2197675230-40">}</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="k">receive</span><span class="w">
│ │ │ -		</span><span class="p" data-group-id="6425242463-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="6425242463-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -		    </span><span class="nf">exit</span><span class="p" data-group-id="6425242463-43">(</span><span class="ss">normal</span><span class="p" data-group-id="6425242463-43">)</span><span class="w">
│ │ │ +		</span><span class="p" data-group-id="2197675230-42">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="ss">closed</span><span class="p" data-group-id="2197675230-42">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +		    </span><span class="nf">exit</span><span class="p" data-group-id="2197675230-43">(</span><span class="ss">normal</span><span class="p" data-group-id="2197675230-43">)</span><span class="w">
│ │ │  	    </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="6425242463-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="6425242463-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="nf">exit</span><span class="p" data-group-id="6425242463-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="6425242463-45">)</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="2197675230-44">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2197675230-44">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	    </span><span class="nf">exit</span><span class="p" data-group-id="2197675230-45">(</span><span class="ss">port_terminated</span><span class="p" data-group-id="2197675230-45">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Notice that calling <code class="inline">complex2:foo/1</code> and <code class="inline">complex2:bar/1</code> results in the tuple
│ │ │  <code class="inline">{foo,X}</code> or <code class="inline">{bar,Y}</code> being sent to the <code class="inline">complex</code> process, which codes them as
│ │ │  binaries and sends them to the port. This means that the C program must be able
│ │ │  to handle these two tuples.</p><h2 id="c-program" class="section-heading">
│ │ │    <a href="#c-program" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -362,27 +362,27 @@
│ │ │      -L/usr/local/otp/lib/erl_interface-3.9.2/lib \
│ │ │      complex.c erl_comm.c ei.c -lei -lpthread</code></pre><p>In Erlang/OTP R5B and later versions of OTP, the <code class="inline">include</code> and <code class="inline">lib</code> directories
│ │ │  are situated under <code class="inline">$OTPROOT/lib/erl_interface-VSN</code>, where <code class="inline">$OTPROOT</code> is the
│ │ │  root directory of the OTP installation (<code class="inline">/usr/local/otp</code> in the recent example)
│ │ │  and <code class="inline">VSN</code> is the version of the Erl_interface application (3.2.1 in the recent
│ │ │  example).</p><p>In R4B and earlier versions of OTP, <code class="inline">include</code> and <code class="inline">lib</code> are situated under
│ │ │  <code class="inline">$OTPROOT/usr</code>.</p><p><em>Step 2.</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="sc">$ </span><span class="ss">erl</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="1524708387-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="1524708387-1">]</span><span class="w"> </span><span class="p" data-group-id="1524708387-2">[</span><span class="ss">source</span><span class="p" data-group-id="1524708387-2">]</span><span class="w"> </span><span class="p" data-group-id="1524708387-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="1524708387-3">]</span><span class="w"> </span><span class="p" data-group-id="1524708387-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="1524708387-4">]</span><span class="w"> </span><span class="p" data-group-id="1524708387-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="1524708387-5">]</span><span class="w"> </span><span class="p" data-group-id="1524708387-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="1524708387-6">]</span><span class="w"> </span><span class="p" data-group-id="1524708387-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="1524708387-7">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="p" data-group-id="9341272854-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">14.2</span><span class="p" data-group-id="9341272854-1">]</span><span class="w"> </span><span class="p" data-group-id="9341272854-2">[</span><span class="ss">source</span><span class="p" data-group-id="9341272854-2">]</span><span class="w"> </span><span class="p" data-group-id="9341272854-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="9341272854-3">]</span><span class="w"> </span><span class="p" data-group-id="9341272854-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="9341272854-4">]</span><span class="w"> </span><span class="p" data-group-id="9341272854-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="9341272854-5">]</span><span class="w"> </span><span class="p" data-group-id="9341272854-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="9341272854-6">]</span><span class="w"> </span><span class="p" data-group-id="9341272854-7">[</span><span class="nc">jit</span><span class="p">:</span><span class="ss">ns</span><span class="p" data-group-id="9341272854-7">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="1524708387-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="1524708387-9">(</span><span class="p" data-group-id="1524708387-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="1524708387-8">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="1524708387-10">(</span><span class="ss">complex2</span><span class="p" data-group-id="1524708387-10">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1524708387-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex2</span><span class="p" data-group-id="1524708387-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="3575845093-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="3575845093-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V14</span><span class="p">.</span><span class="mi">2</span><span class="w"> </span><span class="p" data-group-id="9341272854-8">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="9341272854-9">(</span><span class="p" data-group-id="9341272854-9">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="9341272854-8">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="9341272854-10">(</span><span class="ss">complex2</span><span class="p" data-group-id="9341272854-10">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9341272854-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex2</span><span class="p" data-group-id="9341272854-11">}</span></code></pre><p><em>Step 3.</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5211221740-1">(</span><span class="s">&quot;./extprg&quot;</span><span class="p" data-group-id="5211221740-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.34</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="3575845093-2">(</span><span class="mi">3</span><span class="p" data-group-id="3575845093-2">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="5211221740-2">(</span><span class="mi">3</span><span class="p" data-group-id="5211221740-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="3575845093-3">(</span><span class="mi">5</span><span class="p" data-group-id="3575845093-3">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="5211221740-3">(</span><span class="mi">5</span><span class="p" data-group-id="5211221740-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="3575845093-4">(</span><span class="mi">352</span><span class="p" data-group-id="3575845093-4">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="5211221740-4">(</span><span class="mi">352</span><span class="p" data-group-id="5211221740-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">704</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="3575845093-5">(</span><span class="p" data-group-id="3575845093-5">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="nc">complex2</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="5211221740-5">(</span><span class="p" data-group-id="5211221740-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">stop</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="c_port.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/error_logging.html
│ │ │ @@ -143,39 +143,39 @@
│ │ │  reports and other error and information reports are by default logged through
│ │ │  the log handler which is set up when the Kernel application is started.</p><p>Prior to Erlang/OTP 21.0, supervisor, crash, and progress reports were only
│ │ │  logged when the SASL application was running. This behaviour can, for backwards
│ │ │  compatibility, be enabled by setting the Kernel configuration parameter
│ │ │  <a href="../../lib/kernel-10.2.7.2/doc/html/kernel_app.html#logger_sasl_compatible"><code class="inline">logger_sasl_compatible</code></a> to
│ │ │  <code class="inline">true</code>. For more information, see
│ │ │  <a href="../../lib/sasl-4.2.2/doc/html/error_logging.html">SASL Error Logging</a> in the SASL User's Guide.</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -kernel logger_level info</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">21</span><span class="w"> </span><span class="p" data-group-id="7887494738-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">10.0</span><span class="p" data-group-id="7887494738-1">]</span><span class="w"> </span><span class="p" data-group-id="7887494738-2">[</span><span class="ss">source</span><span class="o">-</span><span class="mi">13</span><span class="ss">c50db</span><span class="p" data-group-id="7887494738-2">]</span><span class="w"> </span><span class="p" data-group-id="7887494738-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="7887494738-3">]</span><span class="w"> </span><span class="p" data-group-id="7887494738-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="7887494738-4">]</span><span class="w"> </span><span class="p" data-group-id="7887494738-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="7887494738-5">]</span><span class="w"> </span><span class="p" data-group-id="7887494738-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="7887494738-6">]</span><span class="w"> </span><span class="p" data-group-id="7887494738-7">[</span><span class="ss">hipe</span><span class="p" data-group-id="7887494738-7">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">21</span><span class="w"> </span><span class="p" data-group-id="3637992253-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">10.0</span><span class="p" data-group-id="3637992253-1">]</span><span class="w"> </span><span class="p" data-group-id="3637992253-2">[</span><span class="ss">source</span><span class="o">-</span><span class="mi">13</span><span class="ss">c50db</span><span class="p" data-group-id="3637992253-2">]</span><span class="w"> </span><span class="p" data-group-id="3637992253-3">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="3637992253-3">]</span><span class="w"> </span><span class="p" data-group-id="3637992253-4">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="3637992253-4">]</span><span class="w"> </span><span class="p" data-group-id="3637992253-5">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="3637992253-5">]</span><span class="w"> </span><span class="p" data-group-id="3637992253-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3637992253-6">]</span><span class="w"> </span><span class="p" data-group-id="3637992253-7">[</span><span class="ss">hipe</span><span class="p" data-group-id="3637992253-7">]</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.916404</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │      </span><span class="nc">application</span><span class="p">:</span><span class="w"> </span><span class="ss">kernel</span><span class="w">
│ │ │      </span><span class="nc">started_at</span><span class="p">:</span><span class="w"> </span><span class="ss">nonode@nohost</span><span class="w">
│ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.922908</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │      </span><span class="nc">application</span><span class="p">:</span><span class="w"> </span><span class="ss">stdlib</span><span class="w">
│ │ │      </span><span class="nc">started_at</span><span class="p">:</span><span class="w"> </span><span class="ss">nonode@nohost</span><span class="w">
│ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.925755</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7887494738-8">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="7887494738-8">}</span><span class="w">
│ │ │ -    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7887494738-9">[</span><span class="p" data-group-id="7887494738-10">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.74</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="7887494738-10">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-11">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_sup</span><span class="p" data-group-id="7887494738-11">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-12">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="7887494738-13">{</span><span class="ss">disk_log_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="7887494738-14">[</span><span class="p" data-group-id="7887494738-14">]</span><span class="p" data-group-id="7887494738-13">}</span><span class="p" data-group-id="7887494738-12">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-15">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="7887494738-15">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-16">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">1000</span><span class="p" data-group-id="7887494738-16">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-17">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">supervisor</span><span class="p" data-group-id="7887494738-17">}</span><span class="p" data-group-id="7887494738-9">]</span><span class="w">
│ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3637992253-8">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="3637992253-8">}</span><span class="w">
│ │ │ +    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3637992253-9">[</span><span class="p" data-group-id="3637992253-10">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.74</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3637992253-10">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-11">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_sup</span><span class="p" data-group-id="3637992253-11">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-12">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="3637992253-13">{</span><span class="ss">disk_log_sup</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="3637992253-14">[</span><span class="p" data-group-id="3637992253-14">]</span><span class="p" data-group-id="3637992253-13">}</span><span class="p" data-group-id="3637992253-12">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-15">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="3637992253-15">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-16">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">1000</span><span class="p" data-group-id="3637992253-16">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-17">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">supervisor</span><span class="p" data-group-id="3637992253-17">}</span><span class="p" data-group-id="3637992253-9">]</span><span class="w">
│ │ │  </span><span class="o">=</span><span class="n">PROGRESS</span><span class="w"> </span><span class="n">REPORT</span><span class="o">==</span><span class="o">==</span><span class="w"> </span><span class="mi">8</span><span class="o">-</span><span class="n">Jun</span><span class="o">-</span><span class="mi">2018</span><span class="p">:</span><span class="p">:</span><span class="mi">16</span><span class="p">:</span><span class="mi">54</span><span class="p">:</span><span class="mf">19.926056</span><span class="w"> </span><span class="o">==</span><span class="o">=</span><span class="w">
│ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7887494738-18">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="7887494738-18">}</span><span class="w">
│ │ │ -    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7887494738-19">[</span><span class="p" data-group-id="7887494738-20">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.75</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="7887494738-20">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-21">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_server</span><span class="p" data-group-id="7887494738-21">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-22">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="7887494738-23">{</span><span class="ss">disk_log_server</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="7887494738-24">[</span><span class="p" data-group-id="7887494738-24">]</span><span class="p" data-group-id="7887494738-23">}</span><span class="p" data-group-id="7887494738-22">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-25">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="7887494738-25">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-26">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">2000</span><span class="p" data-group-id="7887494738-26">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7887494738-27">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">worker</span><span class="p" data-group-id="7887494738-27">}</span><span class="p" data-group-id="7887494738-19">]</span><span class="w">
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V10</span><span class="p">.</span><span class="mi">0</span><span class="w">  </span><span class="p" data-group-id="7887494738-28">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="7887494738-28">)</span><span class="w">
│ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3637992253-18">{</span><span class="ss">local</span><span class="p">,</span><span class="ss">kernel_safe_sup</span><span class="p" data-group-id="3637992253-18">}</span><span class="w">
│ │ │ +    </span><span class="nc">started</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3637992253-19">[</span><span class="p" data-group-id="3637992253-20">{</span><span class="ss">pid</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.75</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3637992253-20">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-21">{</span><span class="ss">id</span><span class="p">,</span><span class="ss">disk_log_server</span><span class="p" data-group-id="3637992253-21">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-22">{</span><span class="ss">mfargs</span><span class="p">,</span><span class="p" data-group-id="3637992253-23">{</span><span class="ss">disk_log_server</span><span class="p">,</span><span class="ss">start_link</span><span class="p">,</span><span class="p" data-group-id="3637992253-24">[</span><span class="p" data-group-id="3637992253-24">]</span><span class="p" data-group-id="3637992253-23">}</span><span class="p" data-group-id="3637992253-22">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-25">{</span><span class="ss">restart_type</span><span class="p">,</span><span class="ss">permanent</span><span class="p" data-group-id="3637992253-25">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-26">{</span><span class="ss">shutdown</span><span class="p">,</span><span class="mi">2000</span><span class="p" data-group-id="3637992253-26">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="3637992253-27">{</span><span class="ss">child_type</span><span class="p">,</span><span class="ss">worker</span><span class="p" data-group-id="3637992253-27">}</span><span class="p" data-group-id="3637992253-19">]</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V10</span><span class="p">.</span><span class="mi">0</span><span class="w">  </span><span class="p" data-group-id="3637992253-28">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="3637992253-28">)</span><span class="w">
│ │ │  </span><span class="mi">1</span><span class="o">&gt;</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="system_principles.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/errors.html
│ │ │ @@ -151,22 +151,22 @@
│ │ │  classes, with different origins. The <a href="expressions.html#try">try</a> expression can
│ │ │  distinguish between the different classes, whereas the
│ │ │  <a href="expressions.html#catch-and-throw">catch</a> expression cannot. <code class="inline">try</code> and <code class="inline">catch</code> are described
│ │ │  in <a href="expressions.html">Expressions</a>.</p><table><thead><tr><th style="text-align: left;"><em>Class</em></th><th style="text-align: left;"><em>Origin</em></th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">error</code></td><td style="text-align: left;">Run-time error, for example, <code class="inline">1+a</code>, or the process called <a href="../../erts-15.2.7.3/doc/html/erlang.html#error/1"><code class="inline">error/1</code></a></td></tr><tr><td style="text-align: left;"><code class="inline">exit</code></td><td style="text-align: left;">The process called <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit/1</code></a></td></tr><tr><td style="text-align: left;"><code class="inline">throw</code></td><td style="text-align: left;">The process called <a href="../../erts-15.2.7.3/doc/html/erlang.html#throw/1"><code class="inline">throw/1</code></a></td></tr></tbody></table><p><em>Table: Exception Classes.</em></p><p>All of the above exceptions can also be generated by calling <a href="../../erts-15.2.7.3/doc/html/erlang.html#raise/3"><code class="inline">erlang:raise/3</code></a>.</p><p>An exception consists of its class, an exit reason (see
│ │ │  <a href="errors.html#exit_reasons">Exit Reason</a>), and a stack trace (which aids in finding
│ │ │  the code location of the exception).</p><p>The stack trace can be bound to a variable from within a <code class="inline">try</code> expression for
│ │ │  any exception class, or as part of the exit reason when a run-time error is
│ │ │ -caught by a <code class="inline">catch</code>. Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="3704411730-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="3704411730-2">{</span><span class="ss">test</span><span class="p">,</span><span class="n">Stacktrace</span><span class="p" data-group-id="3704411730-2">}</span><span class="p" data-group-id="3704411730-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3704411730-3">(</span><span class="k">catch</span><span class="w"> </span><span class="nf">error</span><span class="p" data-group-id="3704411730-4">(</span><span class="ss">test</span><span class="p" data-group-id="3704411730-4">)</span><span class="p" data-group-id="3704411730-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Stacktrace</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3704411730-5">[</span><span class="p" data-group-id="3704411730-6">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="3704411730-7">[</span><span class="p" data-group-id="3704411730-7">]</span><span class="p" data-group-id="3704411730-6">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="3704411730-8">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="3704411730-9">[</span><span class="p" data-group-id="3704411730-9">]</span><span class="p" data-group-id="3704411730-8">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3704411730-5">]</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="k">try</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="3704411730-10">(</span><span class="ss">test</span><span class="p" data-group-id="3704411730-10">)</span><span class="w"> </span><span class="k">catch</span><span class="w"> </span><span class="n">Class</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stacktrace</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Stacktrace</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3704411730-11">[</span><span class="p" data-group-id="3704411730-12">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="3704411730-13">[</span><span class="p" data-group-id="3704411730-13">]</span><span class="p" data-group-id="3704411730-12">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="3704411730-14">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="3704411730-15">[</span><span class="p" data-group-id="3704411730-15">]</span><span class="p" data-group-id="3704411730-14">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3704411730-11">]</span></code></pre><p><a href="" id="stacktrace"></a></p><h3 id="the-call-stack-back-trace-stacktrace" class="section-heading">
│ │ │ +caught by a <code class="inline">catch</code>. Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="2081757023-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="2081757023-2">{</span><span class="ss">test</span><span class="p">,</span><span class="n">Stacktrace</span><span class="p" data-group-id="2081757023-2">}</span><span class="p" data-group-id="2081757023-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2081757023-3">(</span><span class="k">catch</span><span class="w"> </span><span class="nf">error</span><span class="p" data-group-id="2081757023-4">(</span><span class="ss">test</span><span class="p" data-group-id="2081757023-4">)</span><span class="p" data-group-id="2081757023-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Stacktrace</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2081757023-5">[</span><span class="p" data-group-id="2081757023-6">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="2081757023-7">[</span><span class="p" data-group-id="2081757023-7">]</span><span class="p" data-group-id="2081757023-6">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2081757023-8">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="2081757023-9">[</span><span class="p" data-group-id="2081757023-9">]</span><span class="p" data-group-id="2081757023-8">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2081757023-5">]</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="k">try</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="2081757023-10">(</span><span class="ss">test</span><span class="p" data-group-id="2081757023-10">)</span><span class="w"> </span><span class="k">catch</span><span class="w"> </span><span class="n">Class</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stacktrace</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Stacktrace</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2081757023-11">[</span><span class="p" data-group-id="2081757023-12">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="2081757023-13">[</span><span class="p" data-group-id="2081757023-13">]</span><span class="p" data-group-id="2081757023-12">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2081757023-14">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="2081757023-15">[</span><span class="p" data-group-id="2081757023-15">]</span><span class="p" data-group-id="2081757023-14">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2081757023-11">]</span></code></pre><p><a href="" id="stacktrace"></a></p><h3 id="the-call-stack-back-trace-stacktrace" class="section-heading">
│ │ │    <a href="#the-call-stack-back-trace-stacktrace" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">The call-stack back trace (stacktrace)</span>
│ │ │  </h3>
│ │ │  <p>The stack back-trace (<a href="../../erts-15.2.7.3/doc/html/erlang.html#t:stacktrace/0"><em>stacktrace</em></a>) is a list that
│ │ │  contains <code class="inline">{Module, Function, Arity, ExtraInfo}</code> and/or <code class="inline">{Fun, Arity, ExtraInfo}</code>
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/events.html
│ │ │ @@ -135,43 +135,43 @@
│ │ │  event handler.</p><h2 id="example" class="section-heading">
│ │ │    <a href="#example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Example</span>
│ │ │  </h2>
│ │ │  <p>The callback module for the event handler writing error messages to the terminal
│ │ │ -can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6182637798-1">(</span><span class="ss">terminal_logger</span><span class="p" data-group-id="6182637798-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="6182637798-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="6182637798-2">)</span><span class="p">.</span><span class="w">
│ │ │ +can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9022855742-1">(</span><span class="ss">terminal_logger</span><span class="p" data-group-id="9022855742-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9022855742-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="9022855742-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6182637798-3">(</span><span class="p" data-group-id="6182637798-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6182637798-4">]</span><span class="p" data-group-id="6182637798-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9022855742-3">(</span><span class="p" data-group-id="9022855742-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9022855742-4">]</span><span class="p" data-group-id="9022855742-3">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="6182637798-5">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="6182637798-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6182637798-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6182637798-7">[</span><span class="p" data-group-id="6182637798-7">]</span><span class="p" data-group-id="6182637798-6">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="9022855742-5">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="9022855742-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9022855742-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9022855742-7">[</span><span class="p" data-group-id="9022855742-7">]</span><span class="p" data-group-id="9022855742-6">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="6182637798-8">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6182637798-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6182637798-9">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6182637798-10">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="6182637798-10">]</span><span class="p" data-group-id="6182637798-9">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6182637798-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6182637798-11">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="9022855742-8">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9022855742-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9022855742-9">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9022855742-10">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="9022855742-10">]</span><span class="p" data-group-id="9022855742-9">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9022855742-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9022855742-11">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="6182637798-12">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="6182637798-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="9022855742-12">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="9022855742-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The callback module for the event handler writing error messages to a file can
│ │ │ -look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2527574125-1">(</span><span class="ss">file_logger</span><span class="p" data-group-id="2527574125-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="2527574125-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="2527574125-2">)</span><span class="p">.</span><span class="w">
│ │ │ +look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2049263762-1">(</span><span class="ss">file_logger</span><span class="p" data-group-id="2049263762-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="2049263762-2">(</span><span class="ss">gen_event</span><span class="p" data-group-id="2049263762-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2527574125-3">(</span><span class="p" data-group-id="2527574125-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2527574125-4">]</span><span class="p" data-group-id="2527574125-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2049263762-3">(</span><span class="p" data-group-id="2049263762-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2049263762-4">]</span><span class="p" data-group-id="2049263762-3">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="2527574125-5">(</span><span class="n">File</span><span class="p" data-group-id="2527574125-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2527574125-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2527574125-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="2527574125-7">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="2527574125-7">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2527574125-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2527574125-8">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="2527574125-9">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2527574125-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2527574125-10">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2527574125-11">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="2527574125-11">]</span><span class="p" data-group-id="2527574125-10">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2527574125-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2527574125-12">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="2049263762-5">(</span><span class="n">File</span><span class="p" data-group-id="2049263762-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2049263762-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2049263762-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="2049263762-7">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="2049263762-7">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2049263762-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2049263762-8">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="2049263762-9">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2049263762-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2049263762-10">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2049263762-11">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="2049263762-11">]</span><span class="p" data-group-id="2049263762-10">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2049263762-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2049263762-12">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="2527574125-13">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2527574125-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="2527574125-14">(</span><span class="n">Fd</span><span class="p" data-group-id="2527574125-14">)</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><p><a href="" id="mgr"></a></p><h2 id="starting-an-event-manager" class="section-heading">
│ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="2049263762-13">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="2049263762-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="2049263762-14">(</span><span class="n">Fd</span><span class="p" data-group-id="2049263762-14">)</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><p><a href="" id="mgr"></a></p><h2 id="starting-an-event-manager" class="section-heading">
│ │ │    <a href="#starting-an-event-manager" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting an Event Manager</span>
│ │ │  </h2>
│ │ │  <p>To start an event manager for handling errors, as described in the previous
│ │ │  example, call the following function:</p><pre><code class="text">gen_event:start_link({local, error_man})</code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/gen_event.html#start_link/1"><code class="inline">gen_event:start_link/1</code></a> spawns and links to a new event manager process.</p><p>The argument, <code class="inline">{local, error_man}</code>, specifies the name under which the
│ │ │ @@ -184,57 +184,57 @@
│ │ │  manager that is not part of a supervision tree.</p><h2 id="adding-an-event-handler" class="section-heading">
│ │ │    <a href="#adding-an-event-handler" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Adding an Event Handler</span>
│ │ │  </h2>
│ │ │  <p>The following example shows how to start an event manager and add an event
│ │ │ -handler to it by using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7316619348-1">(</span><span class="p" data-group-id="7316619348-2">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="7316619348-2">}</span><span class="p" data-group-id="7316619348-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7316619348-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.31</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="7316619348-3">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">add_handler</span><span class="p" data-group-id="7316619348-4">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7316619348-5">[</span><span class="p" data-group-id="7316619348-5">]</span><span class="p" data-group-id="7316619348-4">)</span><span class="p">.</span><span class="w">
│ │ │ +handler to it by using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="7583836812-1">(</span><span class="p" data-group-id="7583836812-2">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="7583836812-2">}</span><span class="p" data-group-id="7583836812-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7583836812-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.31</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="7583836812-3">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">add_handler</span><span class="p" data-group-id="7583836812-4">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7583836812-5">[</span><span class="p" data-group-id="7583836812-5">]</span><span class="p" data-group-id="7583836812-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>This function sends a message to the event manager registered as <code class="inline">error_man</code>,
│ │ │  telling it to add the event handler <code class="inline">terminal_logger</code>. The event manager calls
│ │ │  the callback function <code class="inline">terminal_logger:init([])</code>, where the argument <code class="inline">[]</code> is the
│ │ │  third argument to <code class="inline">add_handler</code>. <code class="inline">init/1</code> is expected to return <code class="inline">{ok, State}</code>,
│ │ │ -where <code class="inline">State</code> is the internal state of the event handler.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="2820551322-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="2820551322-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2820551322-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2820551322-3">[</span><span class="p" data-group-id="2820551322-3">]</span><span class="p" data-group-id="2820551322-2">}</span><span class="p">.</span></code></pre><p>Here, <code class="inline">init/1</code> does not need any input data and ignores its argument. For
│ │ │ +where <code class="inline">State</code> is the internal state of the event handler.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1502396115-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="1502396115-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1502396115-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1502396115-3">[</span><span class="p" data-group-id="1502396115-3">]</span><span class="p" data-group-id="1502396115-2">}</span><span class="p">.</span></code></pre><p>Here, <code class="inline">init/1</code> does not need any input data and ignores its argument. For
│ │ │  <code class="inline">terminal_logger</code>, the internal state is not used. For <code class="inline">file_logger</code>, the
│ │ │ -internal state is used to save the open file descriptor.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="8449207562-1">(</span><span class="n">File</span><span class="p" data-group-id="8449207562-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8449207562-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="8449207562-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="8449207562-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="8449207562-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8449207562-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="8449207562-4">}</span><span class="p">.</span></code></pre><h2 id="notifying-about-events" class="section-heading">
│ │ │ +internal state is used to save the open file descriptor.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="4880389002-1">(</span><span class="n">File</span><span class="p" data-group-id="4880389002-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4880389002-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="4880389002-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="4880389002-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">read</span><span class="p" data-group-id="4880389002-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4880389002-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="4880389002-4">}</span><span class="p">.</span></code></pre><h2 id="notifying-about-events" class="section-heading">
│ │ │    <a href="#notifying-about-events" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Notifying about Events</span>
│ │ │  </h2>
│ │ │  <pre><code class="text">3&gt; gen_event:notify(error_man, no_reply).
│ │ │  ***Error*** no_reply
│ │ │  ok</code></pre><p><code class="inline">error_man</code> is the name of the event manager and <code class="inline">no_reply</code> is the event.</p><p>The event is made into a message and sent to the event manager. When the event
│ │ │  is received, the event manager calls <code class="inline">handle_event(Event, State)</code> for each
│ │ │  installed event handler, in the same order as they were added. The function is
│ │ │  expected to return a tuple <code class="inline">{ok,State1}</code>, where <code class="inline">State1</code> is a new value for the
│ │ │ -state of the event handler.</p><p>In <code class="inline">terminal_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="5712833436-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="5712833436-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5712833436-2">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5712833436-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="5712833436-3">]</span><span class="p" data-group-id="5712833436-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5712833436-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="5712833436-4">}</span><span class="p">.</span></code></pre><p>In <code class="inline">file_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="5805206581-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="5805206581-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5805206581-2">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5805206581-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="5805206581-3">]</span><span class="p" data-group-id="5805206581-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5805206581-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="5805206581-4">}</span><span class="p">.</span></code></pre><h2 id="deleting-an-event-handler" class="section-heading">
│ │ │ +state of the event handler.</p><p>In <code class="inline">terminal_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="7772615062-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7772615062-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7772615062-2">(</span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7772615062-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="7772615062-3">]</span><span class="p" data-group-id="7772615062-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7772615062-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7772615062-4">}</span><span class="p">.</span></code></pre><p>In <code class="inline">file_logger</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_event</span><span class="p" data-group-id="6524933259-1">(</span><span class="n">ErrorMsg</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="6524933259-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6524933259-2">(</span><span class="n">Fd</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;***Error*** </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6524933259-3">[</span><span class="n">ErrorMsg</span><span class="p" data-group-id="6524933259-3">]</span><span class="p" data-group-id="6524933259-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6524933259-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="6524933259-4">}</span><span class="p">.</span></code></pre><h2 id="deleting-an-event-handler" class="section-heading">
│ │ │    <a href="#deleting-an-event-handler" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Deleting an Event Handler</span>
│ │ │  </h2>
│ │ │ -<pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">delete_handler</span><span class="p" data-group-id="5296564592-1">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5296564592-2">[</span><span class="p" data-group-id="5296564592-2">]</span><span class="p" data-group-id="5296564592-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">delete_handler</span><span class="p" data-group-id="6416038221-1">(</span><span class="ss">error_man</span><span class="p">,</span><span class="w"> </span><span class="ss">terminal_logger</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6416038221-2">[</span><span class="p" data-group-id="6416038221-2">]</span><span class="p" data-group-id="6416038221-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>This function sends a message to the event manager registered as <code class="inline">error_man</code>,
│ │ │  telling it to delete the event handler <code class="inline">terminal_logger</code>. The event manager
│ │ │  calls the callback function <code class="inline">terminal_logger:terminate([], State)</code>, where the
│ │ │  argument <code class="inline">[]</code> is the third argument to <code class="inline">delete_handler</code>. <code class="inline">terminate/2</code> is to be
│ │ │  the opposite of <code class="inline">init/1</code> and do any necessary cleaning up. Its return value is
│ │ │ -ignored.</p><p>For <code class="inline">terminal_logger</code>, no cleaning up is necessary:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="1696774124-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="1696774124-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>For <code class="inline">file_logger</code>, the file descriptor opened in <code class="inline">init</code> must be closed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="1275989208-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="1275989208-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="1275989208-2">(</span><span class="n">Fd</span><span class="p" data-group-id="1275989208-2">)</span><span class="p">.</span></code></pre><h2 id="stopping" class="section-heading">
│ │ │ +ignored.</p><p>For <code class="inline">terminal_logger</code>, no cleaning up is necessary:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="1968302327-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p" data-group-id="1968302327-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>For <code class="inline">file_logger</code>, the file descriptor opened in <code class="inline">init</code> must be closed:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="3416685041-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="3416685041-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="3416685041-2">(</span><span class="n">Fd</span><span class="p" data-group-id="3416685041-2">)</span><span class="p">.</span></code></pre><h2 id="stopping" class="section-heading">
│ │ │    <a href="#stopping" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Stopping</span>
│ │ │  </h2>
│ │ │  <p>When an event manager is stopped, it gives each of the installed event handlers
│ │ │  the chance to clean up by calling <code class="inline">terminate/2</code>, the same way as when deleting a
│ │ │ @@ -249,33 +249,33 @@
│ │ │  this is done is defined by a <a href="sup_princ.html#shutdown">shutdown strategy</a> set in
│ │ │  the supervisor.</p><h3 id="standalone-event-managers" class="section-heading">
│ │ │    <a href="#standalone-event-managers" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Standalone Event Managers</span>
│ │ │  </h3>
│ │ │ -<p>An event manager can also be stopped by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="6735249689-1">(</span><span class="ss">error_man</span><span class="p" data-group-id="6735249689-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>An event manager can also be stopped by calling:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">gen_event</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="6427540183-1">(</span><span class="ss">error_man</span><span class="p" data-group-id="6427540183-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><h2 id="handling-other-messages" class="section-heading">
│ │ │    <a href="#handling-other-messages" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Handling Other Messages</span>
│ │ │  </h2>
│ │ │  <p>If the <code class="inline">gen_event</code> process is to be able to receive other messages
│ │ │  than events, the callback function <code class="inline">handle_info(Info, State)</code> must be
│ │ │  implemented to handle them. Examples of other messages are exit
│ │ │  messages if the event manager is linked to other processes than the
│ │ │  supervisor (for example via <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_event.html#add_sup_handler/3"><code class="inline">gen_event:add_sup_handler/3</code></a>) and is
│ │ │ -trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="1461468463-1">(</span><span class="p" data-group-id="1461468463-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="1461468463-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1461468463-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="0922073905-1">(</span><span class="p" data-group-id="0922073905-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="0922073905-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="0922073905-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Code to handle exits here.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1461468463-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="1461468463-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="0446990991-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="0446990991-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0922073905-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="0922073905-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="9008901455-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="9008901455-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Code to convert state (and more) during code change.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0446990991-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="0446990991-2">}</span><span class="p">.</span></code></pre>
│ │ │ +    </span><span class="p" data-group-id="9008901455-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="9008901455-2">}</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="statem.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/example.html
│ │ │ @@ -131,15 +131,15 @@
│ │ │  
│ │ │  int bar(int y) {
│ │ │    return y*2;
│ │ │  }</code></pre><p>The functions are deliberately kept as simple as possible, for readability
│ │ │  reasons.</p><p>From an Erlang perspective, it is preferable to be able to call <code class="inline">foo</code> and <code class="inline">bar</code>
│ │ │  without having to bother about that they are C functions:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% Erlang code</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="n">Res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">complex</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="4558834628-1">(</span><span class="n">X</span><span class="p" data-group-id="4558834628-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">complex</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="0140442217-1">(</span><span class="n">X</span><span class="p" data-group-id="0140442217-1">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Here, the communication with C is hidden in the implementation of <code class="inline">complex.erl</code>.
│ │ │  In the following sections, it is shown how this module can be implemented using
│ │ │  the different interoperability mechanisms.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/expressions.html
│ │ │ @@ -151,81 +151,81 @@
│ │ │  </span><span class="n">Phone_number</span><span class="w">
│ │ │  </span><span class="p">_</span><span class="w">
│ │ │  </span><span class="p">_</span><span class="n">Height</span><span class="w">
│ │ │  </span><span class="ss">name@node</span></code></pre><p>Variables are bound to values using <a href="patterns.html">pattern matching</a>. Erlang uses
│ │ │  <em>single assignment</em>, that is, a variable can only be bound once.</p><p>The <em>anonymous variable</em> is denoted by underscore (_) and can be used when a
│ │ │  variable is required but its value can be ignored.</p><p><em>Example:</em></p><pre><code class="text">[H|_] = [1,2,3]</code></pre><p>Variables starting with underscore (<code class="inline">_</code>), for example, <code class="inline">_Height</code>, are normal
│ │ │  variables, not anonymous. However, they are ignored by the compiler in the sense
│ │ │ -that they do not generate warnings.</p><p><em>Example:</em></p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="8240341457-1">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8240341457-2">[</span><span class="p" data-group-id="8240341457-2">]</span><span class="p" data-group-id="8240341457-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8240341457-3">[</span><span class="p" data-group-id="8240341457-3">]</span><span class="p">.</span></code></pre><p>can be rewritten to be more readable:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="0555256832-1">(</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0555256832-2">[</span><span class="p" data-group-id="0555256832-2">]</span><span class="p" data-group-id="0555256832-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0555256832-3">[</span><span class="p" data-group-id="0555256832-3">]</span><span class="p">.</span></code></pre><p>This causes a warning for an unused variable, <code class="inline">Elem</code>. To avoid the warning,
│ │ │ -the code can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="2645892099-1">(</span><span class="p">_</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2645892099-2">[</span><span class="p" data-group-id="2645892099-2">]</span><span class="p" data-group-id="2645892099-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2645892099-3">[</span><span class="p" data-group-id="2645892099-3">]</span><span class="p">.</span></code></pre><p>Notice that since variables starting with an underscore are not anonymous, the
│ │ │ -following example matches:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9159877110-1">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9159877110-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9159877110-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9159877110-2">}</span></code></pre><p>But this example fails:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1568901650-1">{</span><span class="p">_</span><span class="n">N</span><span class="p">,</span><span class="p">_</span><span class="n">N</span><span class="p" data-group-id="1568901650-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1568901650-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1568901650-2">}</span></code></pre><p>The scope for a variable is its function clause. Variables bound in a branch of
│ │ │ +that they do not generate warnings.</p><p><em>Example:</em></p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="3693899869-1">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3693899869-2">[</span><span class="p" data-group-id="3693899869-2">]</span><span class="p" data-group-id="3693899869-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3693899869-3">[</span><span class="p" data-group-id="3693899869-3">]</span><span class="p">.</span></code></pre><p>can be rewritten to be more readable:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="0269103796-1">(</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0269103796-2">[</span><span class="p" data-group-id="0269103796-2">]</span><span class="p" data-group-id="0269103796-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0269103796-3">[</span><span class="p" data-group-id="0269103796-3">]</span><span class="p">.</span></code></pre><p>This causes a warning for an unused variable, <code class="inline">Elem</code>. To avoid the warning,
│ │ │ +the code can be rewritten to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">member</span><span class="p" data-group-id="3080465796-1">(</span><span class="p">_</span><span class="n">Elem</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3080465796-2">[</span><span class="p" data-group-id="3080465796-2">]</span><span class="p" data-group-id="3080465796-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3080465796-3">[</span><span class="p" data-group-id="3080465796-3">]</span><span class="p">.</span></code></pre><p>Notice that since variables starting with an underscore are not anonymous, the
│ │ │ +following example matches:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1556225360-1">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="1556225360-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1556225360-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1556225360-2">}</span></code></pre><p>But this example fails:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0441271106-1">{</span><span class="p">_</span><span class="n">N</span><span class="p">,</span><span class="p">_</span><span class="n">N</span><span class="p" data-group-id="0441271106-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0441271106-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0441271106-2">}</span></code></pre><p>The scope for a variable is its function clause. Variables bound in a branch of
│ │ │  an <code class="inline">if</code>, <code class="inline">case</code>, or <code class="inline">receive</code> expression must be bound in all branches to have a
│ │ │  value outside the expression. Otherwise they are regarded as unsafe outside
│ │ │  the expression.</p><p>For the <code class="inline">try</code> expression variable scoping is limited so that variables bound in
│ │ │  the expression are always unsafe outside the expression.</p><h2 id="patterns" class="section-heading">
│ │ │    <a href="#patterns" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Patterns</span>
│ │ │  </h2>
│ │ │  <p>A pattern has the same structure as a term but can contain unbound variables.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">Name1</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2386591520-1">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2386591520-1">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2386591520-2">{</span><span class="ss">error</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="2386591520-2">}</span></code></pre><p>Patterns are allowed in clause heads, <a href="expressions.html#case">case expressions</a>,
│ │ │ +</span><span class="p" data-group-id="8443072283-1">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8443072283-1">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8443072283-2">{</span><span class="ss">error</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="8443072283-2">}</span></code></pre><p>Patterns are allowed in clause heads, <a href="expressions.html#case">case expressions</a>,
│ │ │  <a href="expressions.html#receive">receive expressions</a>, and
│ │ │  <a href="expressions.html#the-match-operator">match expressions</a>.</p><h3 id="the-compound-pattern-operator" class="section-heading">
│ │ │    <a href="#the-compound-pattern-operator" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">The Compound Pattern Operator</span>
│ │ │  </h3>
│ │ │  <p>If <code class="inline">Pattern1</code> and <code class="inline">Pattern2</code> are valid patterns, the following is also a valid
│ │ │  pattern:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Pattern2</span></code></pre><p>When matched against a term, both <code class="inline">Pattern1</code> and <code class="inline">Pattern2</code> are matched against
│ │ │ -the term. The idea behind this feature is to avoid reconstruction of terms.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="2730043851-1">(</span><span class="p" data-group-id="2730043851-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="2730043851-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="2730043851-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Signal</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2730043851-3">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="2730043851-3">}</span><span class="p">,</span><span class="w">
│ │ │ +the term. The idea behind this feature is to avoid reconstruction of terms.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="9839662146-1">(</span><span class="p" data-group-id="9839662146-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="9839662146-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="9839662146-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Signal</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9839662146-3">{</span><span class="ss">connect</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="n">Number</span><span class="p">,</span><span class="n">Options</span><span class="p" data-group-id="9839662146-3">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="2730043851-4">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="2730043851-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ignore</span><span class="p">.</span></code></pre><p>can instead be written as</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="4512783421-1">(</span><span class="p" data-group-id="4512783421-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4512783421-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="4512783421-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="9839662146-4">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="9839662146-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ignore</span><span class="p">.</span></code></pre><p>can instead be written as</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="9587555243-1">(</span><span class="p" data-group-id="9587555243-2">{</span><span class="ss">connect</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="n">To</span><span class="p">,</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9587555243-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="9587555243-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="4512783421-3">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="4512783421-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="9587555243-3">(</span><span class="n">Signal</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="9587555243-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">ignore</span><span class="p">.</span></code></pre><p>The compound pattern operator does not imply that its operands are matched in
│ │ │  any particular order. That means that it is not legal to bind a variable in
│ │ │  <code class="inline">Pattern1</code> and use it in <code class="inline">Pattern2</code>, or vice versa.</p><h3 id="string-prefix-in-patterns" class="section-heading">
│ │ │    <a href="#string-prefix-in-patterns" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">String Prefix in Patterns</span>
│ │ │  </h3>
│ │ │ -<p>When matching strings, the following is a valid pattern:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="8413957386-1">(</span><span class="s">&quot;prefix&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="8413957386-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This is syntactic sugar for the equivalent, but harder to read:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="1730753309-1">(</span><span class="p" data-group-id="1730753309-2">[</span><span class="sc">$p</span><span class="p">,</span><span class="sc">$r</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$f</span><span class="p">,</span><span class="sc">$i</span><span class="p">,</span><span class="sc">$x</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="1730753309-2">]</span><span class="p" data-group-id="1730753309-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h3 id="expressions-in-patterns" class="section-heading">
│ │ │ +<p>When matching strings, the following is a valid pattern:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="9464032501-1">(</span><span class="s">&quot;prefix&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="9464032501-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This is syntactic sugar for the equivalent, but harder to read:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="8053647057-1">(</span><span class="p" data-group-id="8053647057-2">[</span><span class="sc">$p</span><span class="p">,</span><span class="sc">$r</span><span class="p">,</span><span class="sc">$e</span><span class="p">,</span><span class="sc">$f</span><span class="p">,</span><span class="sc">$i</span><span class="p">,</span><span class="sc">$x</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Str</span><span class="p" data-group-id="8053647057-2">]</span><span class="p" data-group-id="8053647057-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h3 id="expressions-in-patterns" class="section-heading">
│ │ │    <a href="#expressions-in-patterns" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Expressions in Patterns</span>
│ │ │  </h3>
│ │ │  <p>An arithmetic expression can be used within a pattern if it meets both of the
│ │ │ -following two conditions:</p><ul><li>It uses only numeric or bitwise operators.</li><li>Its value can be evaluated to a constant when complied.</li></ul><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="p" data-group-id="6583175971-1">{</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6583175971-1">}</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6583175971-2">{</span><span class="o">?</span><span class="n">THRESHOLD</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="6583175971-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="the-match-operator" class="section-heading">
│ │ │ +following two conditions:</p><ul><li>It uses only numeric or bitwise operators.</li><li>Its value can be evaluated to a constant when complied.</li></ul><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="p" data-group-id="9887717908-1">{</span><span class="n">Value</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="9887717908-1">}</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9887717908-2">{</span><span class="o">?</span><span class="n">THRESHOLD</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="9887717908-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="the-match-operator" class="section-heading">
│ │ │    <a href="#the-match-operator" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">The Match Operator</span>
│ │ │  </h2>
│ │ │  <p>The following matches <code class="inline">Pattern</code> against <code class="inline">Expr</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>If the matching succeeds, any unbound variable in the pattern becomes bound and
│ │ │  the value of <code class="inline">Expr</code> is returned.</p><p>If multiple match operators are applied in sequence, they will be evaluated from
│ │ │ -right to left.</p><p>If the matching fails, a <code class="inline">badmatch</code> run-time error occurs.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="8363573191-1">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="8363573191-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8363573191-2">{</span><span class="ss">answer</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="8363573191-2">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8363573191-3">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="8363573191-3">}</span><span class="gp unselectable">
│ │ │ +right to left.</p><p>If the matching fails, a <code class="inline">badmatch</code> run-time error occurs.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="2468135332-1">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="2468135332-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2468135332-2">{</span><span class="ss">answer</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="2468135332-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2468135332-3">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="2468135332-3">}</span><span class="gp unselectable">
│ │ │  2&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">answer</span><span class="gp unselectable">
│ │ │  3&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │  4&gt; </span><span class="n">T</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8363573191-4">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="8363573191-4">}</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="p" data-group-id="8363573191-5">{</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="8363573191-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8363573191-6">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="8363573191-6">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2468135332-4">{</span><span class="ss">answer</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="2468135332-4">}</span><span class="gp unselectable">
│ │ │ +5&gt; </span><span class="p" data-group-id="2468135332-5">{</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="2468135332-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2468135332-6">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2468135332-6">]</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no match of right-hand side value [1,2]</span></code></pre><p>Because multiple match operators are evaluated from right to left, it means
│ │ │  that:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Pattern2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">PatternN</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expression</span></code></pre><p>is equivalent to:</p><pre><code class="makeup erlang" translate="no"><span class="n">Temporary</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expression</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="n">PatternN</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Temporary</span><span class="p">,</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="n">Pattern2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Temporary</span><span class="p">,</span><span class="w">
│ │ │ @@ -239,30 +239,30 @@
│ │ │  can safely be skipped on a first reading.</p></section><p>The <code class="inline">=</code> character is used to denote two similar but distinct operators: the
│ │ │  match operator and the compound pattern operator. Which one is meant is
│ │ │  determined by context.</p><p>The <em>compound pattern operator</em> is used to construct a compound pattern from two
│ │ │  patterns. Compound patterns are accepted everywhere a pattern is accepted. A
│ │ │  compound pattern matches if all of its constituent patterns match. It is not
│ │ │  legal for a pattern that is part of a compound pattern to use variables (as keys
│ │ │  in map patterns or sizes in binary patterns) bound in other sub patterns of the
│ │ │ -same compound pattern.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">fun</span><span class="p" data-group-id="3120169531-1">(</span><span class="p" data-group-id="3120169531-2">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="3120169531-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3120169531-3">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="3120169531-3">}</span><span class="p" data-group-id="3120169531-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +same compound pattern.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">fun</span><span class="p" data-group-id="4114427133-1">(</span><span class="p" data-group-id="4114427133-2">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="4114427133-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4114427133-3">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="4114427133-3">}</span><span class="p" data-group-id="4114427133-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">* 1:7: variable &#39;Key&#39; is unbound</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3120169531-4">(</span><span class="p" data-group-id="3120169531-5">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="3120169531-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">E</span><span class="p" data-group-id="3120169531-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3120169531-6">{</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="3120169531-6">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="3120169531-7">(</span><span class="p" data-group-id="3120169531-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3120169531-8">}</span><span class="p" data-group-id="3120169531-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3120169531-9">{</span><span class="p" data-group-id="3120169531-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3120169531-10">}</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3120169531-9">}</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="n">G</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3120169531-11">(</span><span class="p" data-group-id="3120169531-12">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">B</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3120169531-12">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3120169531-13">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="3120169531-13">&gt;&gt;</span><span class="p" data-group-id="3120169531-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3120169531-14">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="3120169531-14">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">G</span><span class="p" data-group-id="3120169531-15">(</span><span class="p" data-group-id="3120169531-16">&lt;&lt;</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p" data-group-id="3120169531-16">&gt;&gt;</span><span class="p" data-group-id="3120169531-15">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3120169531-17">{</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p">,</span><span class="mi">10795</span><span class="p" data-group-id="3120169531-17">}</span></code></pre><p>The <em>match operator</em> is allowed everywhere an expression is allowed. It is used
│ │ │ +2&gt; </span><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4114427133-4">(</span><span class="p" data-group-id="4114427133-5">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="4114427133-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">E</span><span class="p" data-group-id="4114427133-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4114427133-6">{</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="4114427133-6">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="4114427133-7">(</span><span class="p" data-group-id="4114427133-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4114427133-8">}</span><span class="p" data-group-id="4114427133-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4114427133-9">{</span><span class="p" data-group-id="4114427133-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="4114427133-10">}</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4114427133-9">}</span><span class="gp unselectable">
│ │ │ +3&gt; </span><span class="n">G</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4114427133-11">(</span><span class="p" data-group-id="4114427133-12">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">B</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="4114427133-12">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4114427133-13">&lt;&lt;</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="4114427133-13">&gt;&gt;</span><span class="p" data-group-id="4114427133-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4114427133-14">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="4114427133-14">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">G</span><span class="p" data-group-id="4114427133-15">(</span><span class="p" data-group-id="4114427133-16">&lt;&lt;</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p" data-group-id="4114427133-16">&gt;&gt;</span><span class="p" data-group-id="4114427133-15">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4114427133-17">{</span><span class="mi">42</span><span class="p">,</span><span class="mi">43</span><span class="p">,</span><span class="mi">10795</span><span class="p" data-group-id="4114427133-17">}</span></code></pre><p>The <em>match operator</em> is allowed everywhere an expression is allowed. It is used
│ │ │  to match the value of an expression to a pattern. If multiple match operators
│ │ │ -are applied in sequence, they will be evaluated from right to left.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0381050913-1">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="0381050913-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0381050913-2">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="0381050913-2">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">f</span><span class="p" data-group-id="0381050913-3">(</span><span class="n">Key</span><span class="p" data-group-id="0381050913-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0381050913-4">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="0381050913-4">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0381050913-5">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="0381050913-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ +are applied in sequence, they will be evaluated from right to left.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5357102904-1">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="5357102904-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5357102904-2">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">key2</span><span class="p">,</span><span class="ss">key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="5357102904-2">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nf">f</span><span class="p" data-group-id="5357102904-3">(</span><span class="n">Key</span><span class="p" data-group-id="5357102904-3">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5357102904-4">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="5357102904-4">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5357102904-5">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="5357102904-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">value</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nf">f</span><span class="p" data-group-id="0381050913-6">(</span><span class="n">Key</span><span class="p" data-group-id="0381050913-6">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0381050913-7">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="0381050913-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0381050913-8">(</span><span class="p" data-group-id="0381050913-9">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="0381050913-9">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p" data-group-id="0381050913-8">)</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nf">f</span><span class="p" data-group-id="5357102904-6">(</span><span class="n">Key</span><span class="p" data-group-id="5357102904-6">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5357102904-7">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="5357102904-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5357102904-8">(</span><span class="p" data-group-id="5357102904-9">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="5357102904-9">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p" data-group-id="5357102904-8">)</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">value</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nf">f</span><span class="p" data-group-id="0381050913-10">(</span><span class="n">Key</span><span class="p" data-group-id="0381050913-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0381050913-11">(</span><span class="p" data-group-id="0381050913-12">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="0381050913-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0381050913-13">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="0381050913-13">}</span><span class="p" data-group-id="0381050913-11">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nf">f</span><span class="p" data-group-id="5357102904-10">(</span><span class="n">Key</span><span class="p" data-group-id="5357102904-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5357102904-11">(</span><span class="p" data-group-id="5357102904-12">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="5357102904-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5357102904-13">#{</span><span class="ss">key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="5357102904-13">}</span><span class="p" data-group-id="5357102904-11">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="n">Value</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">* 1:12: variable &#39;Key&#39; is unbound</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="p" data-group-id="0381050913-14">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">Y</span><span class="p" data-group-id="0381050913-14">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">begin</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0381050913-15">&lt;&lt;</span><span class="mi">42</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="0381050913-15">&gt;&gt;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="p" data-group-id="5357102904-14">&lt;&lt;</span><span class="n">X</span><span class="p">:</span><span class="n">Y</span><span class="p" data-group-id="5357102904-14">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">begin</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5357102904-15">&lt;&lt;</span><span class="mi">42</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="5357102904-15">&gt;&gt;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span></code></pre><p>The expression at prompt <code class="inline">2&gt;</code> first matches the value of variable <code class="inline">M</code> against
│ │ │  pattern <code class="inline">#{key := Key}</code>, binding variable <code class="inline">Key</code>. It then matches the value of
│ │ │  <code class="inline">M</code> against pattern <code class="inline">#{Key := Value}</code> using variable <code class="inline">Key</code> as the key, binding
│ │ │  variable <code class="inline">Value</code>.</p><p>The expression at prompt <code class="inline">3&gt;</code> matches expression <code class="inline">(#{key := Key} = M)</code> against
│ │ │  pattern <code class="inline">#{Key := Value}</code>. The expression inside the parentheses is evaluated
│ │ │  first. That is, <code class="inline">M</code> is matched against <code class="inline">#{key := Key}</code>, and then the value of
│ │ │  <code class="inline">M</code> is matched against pattern <code class="inline">#{Key := Value}</code>. That is the same evaluation
│ │ │ @@ -276,30 +276,30 @@
│ │ │  binding variable <code class="inline">Y</code> and creating a binary. The binary is then matched against
│ │ │  pattern <code class="inline">&lt;&lt;X:Y&gt;&gt;</code> using the value of <code class="inline">Y</code> as the size of the segment.</p><h2 id="function-calls" class="section-heading">
│ │ │    <a href="#function-calls" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Function Calls</span>
│ │ │  </h2>
│ │ │ -<pre><code class="makeup erlang" translate="no"><span class="n">ExprF</span><span class="p" data-group-id="8012246802-1">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="8012246802-1">)</span><span class="w">
│ │ │ -</span><span class="n">ExprM</span><span class="p">:</span><span class="n">ExprF</span><span class="p" data-group-id="8012246802-2">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="8012246802-2">)</span></code></pre><p>In the first form of function calls, <code class="inline">ExprM:ExprF(Expr1,...,ExprN)</code>, each of
│ │ │ +<pre><code class="makeup erlang" translate="no"><span class="n">ExprF</span><span class="p" data-group-id="8703920026-1">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="8703920026-1">)</span><span class="w">
│ │ │ +</span><span class="n">ExprM</span><span class="p">:</span><span class="n">ExprF</span><span class="p" data-group-id="8703920026-2">(</span><span class="n">Expr1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ExprN</span><span class="p" data-group-id="8703920026-2">)</span></code></pre><p>In the first form of function calls, <code class="inline">ExprM:ExprF(Expr1,...,ExprN)</code>, each of
│ │ │  <code class="inline">ExprM</code> and <code class="inline">ExprF</code> must be an atom or an expression that evaluates to an atom.
│ │ │  The function is said to be called by using the <em>fully qualified function name</em>.
│ │ │ -This is often referred to as a <em>remote</em> or <em>external function call</em>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="5201005182-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5201005182-1">)</span></code></pre><p>In the second form of function calls, <code class="inline">ExprF(Expr1,...,ExprN)</code>, <code class="inline">ExprF</code> must be
│ │ │ +This is often referred to as a <em>remote</em> or <em>external function call</em>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="4558072172-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="4558072172-1">)</span></code></pre><p>In the second form of function calls, <code class="inline">ExprF(Expr1,...,ExprN)</code>, <code class="inline">ExprF</code> must be
│ │ │  an atom or evaluate to a fun.</p><p>If <code class="inline">ExprF</code> is an atom, the function is said to be called by using the
│ │ │  <em>implicitly qualified function name</em>. If the function <code class="inline">ExprF</code> is locally
│ │ │  defined, it is called. Alternatively, if <code class="inline">ExprF</code> is explicitly imported from the
│ │ │  <code class="inline">M</code> module, <code class="inline">M:ExprF(Expr1,...,ExprN)</code> is called. If <code class="inline">ExprF</code> is neither declared
│ │ │  locally nor explicitly imported, <code class="inline">ExprF</code> must be the name of an automatically
│ │ │ -imported BIF.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="6713599135-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6713599135-1">)</span><span class="w">
│ │ │ -</span><span class="nf">spawn</span><span class="p" data-group-id="6713599135-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6713599135-3">[</span><span class="p" data-group-id="6713599135-3">]</span><span class="p" data-group-id="6713599135-2">)</span></code></pre><p><em>Examples</em> where <code class="inline">ExprF</code> is a fun:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="7477972946-1">(</span><span class="n">X</span><span class="p" data-group-id="7477972946-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Fun1</span><span class="p" data-group-id="7477972946-2">(</span><span class="mi">3</span><span class="p" data-group-id="7477972946-2">)</span><span class="p">.</span><span class="w">
│ │ │ +imported BIF.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="1806685612-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1806685612-1">)</span><span class="w">
│ │ │ +</span><span class="nf">spawn</span><span class="p" data-group-id="1806685612-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1806685612-3">[</span><span class="p" data-group-id="1806685612-3">]</span><span class="p" data-group-id="1806685612-2">)</span></code></pre><p><em>Examples</em> where <code class="inline">ExprF</code> is a fun:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="0150074562-1">(</span><span class="n">X</span><span class="p" data-group-id="0150074562-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Fun1</span><span class="p" data-group-id="0150074562-2">(</span><span class="mi">3</span><span class="p" data-group-id="0150074562-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="k">fun</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="ss">append</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7477972946-3">(</span><span class="p" data-group-id="7477972946-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7477972946-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7477972946-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7477972946-5">]</span><span class="p" data-group-id="7477972946-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7477972946-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7477972946-6">]</span><span class="w">
│ │ │ +2&gt; </span><span class="k">fun</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="ss">append</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0150074562-3">(</span><span class="p" data-group-id="0150074562-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0150074562-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0150074562-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0150074562-5">]</span><span class="p" data-group-id="0150074562-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0150074562-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0150074562-6">]</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="o">&gt;</span></code></pre><p>Notice that when calling a local function, there is a difference between using
│ │ │  the implicitly or fully qualified function name. The latter always refers to the
│ │ │  latest version of the module. See
│ │ │  <a href="code_loading.html">Compilation and Code Loading </a>and
│ │ │  <a href="ref_man_functions.html#eval">Function Evaluation</a>.</p><h3 id="local-function-names-clashing-with-auto-imported-bifs" class="section-heading">
│ │ │    <a href="#local-function-names-clashing-with-auto-imported-bifs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -316,40 +316,40 @@
│ │ │  called instead. This is to avoid that future additions to the set of
│ │ │  auto-imported BIFs do not silently change the behavior of old code.</p></section><p>However, to avoid that old (pre R14) code changed its behavior when compiled
│ │ │  with Erlang/OTP version R14A or later, the following restriction applies: If you
│ │ │  override the name of a BIF that was auto-imported in OTP versions prior to R14A
│ │ │  (ERTS version 5.8) and have an implicitly qualified call to that function in
│ │ │  your code, you either need to explicitly remove the auto-import using a compiler
│ │ │  directive, or replace the call with a fully qualified function call. Otherwise
│ │ │ -you get a compilation error. See the following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9938158663-1">(</span><span class="p" data-group-id="9938158663-2">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9938158663-2">]</span><span class="p" data-group-id="9938158663-1">)</span><span class="p">.</span><span class="w">
│ │ │ +you get a compilation error. See the following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8429511417-1">(</span><span class="p" data-group-id="8429511417-2">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8429511417-2">]</span><span class="p" data-group-id="8429511417-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="9938158663-3">(</span><span class="p" data-group-id="9938158663-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="9938158663-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9938158663-5">]</span><span class="p" data-group-id="9938158663-4">}</span><span class="p" data-group-id="9938158663-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="8429511417-3">(</span><span class="p" data-group-id="8429511417-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="8429511417-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8429511417-5">]</span><span class="p" data-group-id="8429511417-4">}</span><span class="p" data-group-id="8429511417-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">length</span><span class="p" data-group-id="9938158663-6">(</span><span class="p" data-group-id="9938158663-7">[</span><span class="p" data-group-id="9938158663-7">]</span><span class="p" data-group-id="9938158663-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">length</span><span class="p" data-group-id="8429511417-6">(</span><span class="p" data-group-id="8429511417-7">[</span><span class="p" data-group-id="8429511417-7">]</span><span class="p" data-group-id="8429511417-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="mi">0</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">length</span><span class="p" data-group-id="9938158663-8">(</span><span class="p" data-group-id="9938158663-9">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9938158663-9">]</span><span class="p" data-group-id="9938158663-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="9938158663-10">(</span><span class="n">T</span><span class="p" data-group-id="9938158663-10">)</span><span class="p">.</span><span class="w"> </span><span class="c1">%% Calls the local function length/1</span><span class="w">
│ │ │ +</span><span class="nf">length</span><span class="p" data-group-id="8429511417-8">(</span><span class="p" data-group-id="8429511417-9">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8429511417-9">]</span><span class="p" data-group-id="8429511417-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="8429511417-10">(</span><span class="n">T</span><span class="p" data-group-id="8429511417-10">)</span><span class="p">.</span><span class="w"> </span><span class="c1">%% Calls the local function length/1</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="9938158663-11">(</span><span class="n">X</span><span class="p" data-group-id="9938158663-11">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="9938158663-12">(</span><span class="n">X</span><span class="p" data-group-id="9938158663-12">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="8429511417-11">(</span><span class="n">X</span><span class="p" data-group-id="8429511417-11">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="8429511417-12">(</span><span class="n">X</span><span class="p" data-group-id="8429511417-12">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │                                    </span><span class="c1">%% which is allowed in guards</span><span class="w">
│ │ │      </span><span class="ss">long</span><span class="p">.</span></code></pre><p>The same logic applies to explicitly imported functions from other modules, as
│ │ │  to locally defined functions. It is not allowed to both import a function from
│ │ │ -another module and have the function declared in the module at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3779401260-1">(</span><span class="p" data-group-id="3779401260-2">[</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3779401260-2">]</span><span class="p" data-group-id="3779401260-1">)</span><span class="p">.</span><span class="w">
│ │ │ +another module and have the function declared in the module at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1852579802-1">(</span><span class="p" data-group-id="1852579802-2">[</span><span class="ss">f</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1852579802-2">]</span><span class="p" data-group-id="1852579802-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="3779401260-3">(</span><span class="p" data-group-id="3779401260-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="3779401260-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3779401260-5">]</span><span class="p" data-group-id="3779401260-4">}</span><span class="p" data-group-id="3779401260-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="1852579802-3">(</span><span class="p" data-group-id="1852579802-4">{</span><span class="ss">no_auto_import</span><span class="p">,</span><span class="p" data-group-id="1852579802-5">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1852579802-5">]</span><span class="p" data-group-id="1852579802-4">}</span><span class="p" data-group-id="1852579802-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% erlang:length/1 no longer autoimported</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="3779401260-6">(</span><span class="ss">mod</span><span class="p">,</span><span class="p" data-group-id="3779401260-7">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3779401260-7">]</span><span class="p" data-group-id="3779401260-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="1852579802-6">(</span><span class="ss">mod</span><span class="p">,</span><span class="p" data-group-id="1852579802-7">[</span><span class="nb">length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1852579802-7">]</span><span class="p" data-group-id="1852579802-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="3779401260-8">(</span><span class="n">X</span><span class="p" data-group-id="3779401260-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="3779401260-9">(</span><span class="n">X</span><span class="p" data-group-id="3779401260-9">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">33</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="1852579802-8">(</span><span class="n">X</span><span class="p" data-group-id="1852579802-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="1852579802-9">(</span><span class="n">X</span><span class="p" data-group-id="1852579802-9">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">33</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">%% Calls erlang:length/1,</span><span class="w">
│ │ │                                     </span><span class="c1">%% which is allowed in guards</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="3779401260-10">(</span><span class="n">X</span><span class="p" data-group-id="3779401260-10">)</span><span class="p">;</span><span class="w">              </span><span class="c1">%% Explicit call to erlang:length in body</span><span class="w">
│ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">length</span><span class="p" data-group-id="1852579802-10">(</span><span class="n">X</span><span class="p" data-group-id="1852579802-10">)</span><span class="p">;</span><span class="w">              </span><span class="c1">%% Explicit call to erlang:length in body</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="3779401260-11">(</span><span class="n">X</span><span class="p" data-group-id="3779401260-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">length</span><span class="p" data-group-id="3779401260-12">(</span><span class="n">X</span><span class="p" data-group-id="3779401260-12">)</span><span class="p">.</span><span class="w">                     </span><span class="c1">%% mod:length/1 is called</span></code></pre><p>For auto-imported BIFs added in Erlang/OTP R14A and thereafter, overriding the
│ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="1852579802-11">(</span><span class="n">X</span><span class="p" data-group-id="1852579802-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">length</span><span class="p" data-group-id="1852579802-12">(</span><span class="n">X</span><span class="p" data-group-id="1852579802-12">)</span><span class="p">.</span><span class="w">                     </span><span class="c1">%% mod:length/1 is called</span></code></pre><p>For auto-imported BIFs added in Erlang/OTP R14A and thereafter, overriding the
│ │ │  name with a local function or explicit import is always allowed. However, if the
│ │ │  <code class="inline">-compile({no_auto_import,[F/A])</code> directive is not used, the compiler issues a
│ │ │  warning whenever the function is called in the module using the implicitly
│ │ │  qualified function name.</p><h2 id="if" class="section-heading">
│ │ │    <a href="#if" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -361,40 +361,40 @@
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">GuardSeqN</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>The branches of an <code class="inline">if</code>-expression are scanned sequentially until a guard
│ │ │  sequence <code class="inline">GuardSeq</code> that evaluates to true is found. Then the corresponding
│ │ │  <code class="inline">Body</code> (a sequence of expressions separated by <code class="inline">,</code>) is evaluated.</p><p>The return value of <code class="inline">Body</code> is the return value of the <code class="inline">if</code> expression.</p><p>If no guard sequence is evaluated as true, an <code class="inline">if_clause</code> run-time error occurs.
│ │ │  If necessary, the guard expression <code class="inline">true</code> can be used in the last branch, as
│ │ │ -that guard sequence is always true.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_greater_than</span><span class="p" data-group-id="5883999327-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5883999327-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +that guard sequence is always true.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_greater_than</span><span class="p" data-group-id="9030800586-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9030800586-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% works as an &#39;else&#39; branch</span><span class="w">
│ │ │              </span><span class="ss">false</span><span class="w">
│ │ │      </span><span class="k">end</span></code></pre><h2 id="case" class="section-heading">
│ │ │    <a href="#case" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Case</span>
│ │ │  </h2>
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">Expr</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="9599271064-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="9599271064-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="1699524858-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="1699524858-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="9599271064-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="9599271064-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="1699524858-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="1699524858-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>The expression <code class="inline">Expr</code> is evaluated and the patterns <code class="inline">Pattern</code> are sequentially
│ │ │  matched against the result. If a match succeeds and the optional guard sequence
│ │ │  <code class="inline">GuardSeq</code> is true, the corresponding <code class="inline">Body</code> is evaluated.</p><p>The return value of <code class="inline">Body</code> is the return value of the <code class="inline">case</code> expression.</p><p>If there is no matching pattern with a true guard sequence, a <code class="inline">case_clause</code>
│ │ │ -run-time error occurs.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_valid_signal</span><span class="p" data-group-id="0797793981-1">(</span><span class="n">Signal</span><span class="p" data-group-id="0797793981-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +run-time error occurs.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_valid_signal</span><span class="p" data-group-id="8630693862-1">(</span><span class="n">Signal</span><span class="p" data-group-id="8630693862-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Signal</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0797793981-2">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="0797793981-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8630693862-2">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="8630693862-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0797793981-3">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="0797793981-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8630693862-3">{</span><span class="ss">signal</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">What</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">To</span><span class="p" data-group-id="8630693862-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="p">_</span><span class="n">Else</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">false</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><h2 id="maybe" class="section-heading">
│ │ │    <a href="#maybe" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -412,57 +412,57 @@
│ │ │  the top-level of a <code class="inline">maybe</code> block. It matches the pattern <code class="inline">Expr1</code> against
│ │ │  <code class="inline">Expr2</code>. If the matching succeeds, any unbound variable in the pattern becomes
│ │ │  bound. If the expression is the last expression in the <code class="inline">maybe</code> block, it also
│ │ │  returns the value of <code class="inline">Expr2</code>. If the matching is unsuccessful, the rest of the
│ │ │  expressions in the <code class="inline">maybe</code> block are skipped and the return value of the <code class="inline">maybe</code>
│ │ │  block is <code class="inline">Expr2</code>.</p><p>None of the variables bound in a <code class="inline">maybe</code> block must be used in the code that
│ │ │  follows the block.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="k">maybe</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7978595810-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="7978595810-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="7978595810-2">(</span><span class="p" data-group-id="7978595810-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3412720898-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="3412720898-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="3412720898-2">(</span><span class="p" data-group-id="3412720898-2">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7978595810-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="7978595810-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="7978595810-4">(</span><span class="p" data-group-id="7978595810-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3412720898-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="3412720898-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="3412720898-4">(</span><span class="p" data-group-id="3412720898-4">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>Let us first assume that <code class="inline">a()</code> returns <code class="inline">{ok,42}</code> and <code class="inline">b()</code> returns <code class="inline">{ok,58}</code>.
│ │ │  With those return values, all of the match operators will succeed, and the
│ │ │  return value of the <code class="inline">maybe</code> block is <code class="inline">A + B</code>, which is equal to <code class="inline">42 + 58 = 100</code>.</p><p>Now let us assume that <code class="inline">a()</code> returns <code class="inline">error</code>. The conditional match operator in
│ │ │  <code class="inline">{ok, A} ?= a()</code> fails to match, and the return value of the <code class="inline">maybe</code> block is
│ │ │  the value of the expression that failed to match, namely <code class="inline">error</code>. Similarly, if
│ │ │  <code class="inline">b()</code> returns <code class="inline">wrong</code>, the return value of the <code class="inline">maybe</code> block is <code class="inline">wrong</code>.</p><p>Finally, let us assume that <code class="inline">a()</code> returns <code class="inline">{ok,-1}</code>. Because <code class="inline">true = A &gt;= 0</code> uses
│ │ │  the match operator <code class="inline">=</code>, a <code class="inline">{badmatch,false}</code> run-time error occurs when the
│ │ │ -expression fails to match the pattern.</p><p>The example can be written in a less succient way using nested case expressions:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="6394529312-1">(</span><span class="p" data-group-id="6394529312-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6394529312-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="6394529312-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +expression fails to match the pattern.</p><p>The example can be written in a less succient way using nested case expressions:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="9292577755-1">(</span><span class="p" data-group-id="9292577755-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9292577755-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="9292577755-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="k">case</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="6394529312-3">(</span><span class="p" data-group-id="6394529312-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="6394529312-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="6394529312-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="k">case</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="9292577755-3">(</span><span class="p" data-group-id="9292577755-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9292577755-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="9292577755-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="n">Other1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="n">Other1</span><span class="w">
│ │ │          </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Other2</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">Other2</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>The <code class="inline">maybe</code> block can be augmented with <code class="inline">else</code> clauses:</p><pre><code class="makeup erlang" translate="no"><span class="k">maybe</span><span class="w">
│ │ │      </span><span class="n">Expr1</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="n">ExprN</span><span class="w">
│ │ │  </span><span class="k">else</span><span class="w">
│ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="9005112557-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="9005112557-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="5368001670-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="5368001670-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="9005112557-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="9005112557-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="5368001670-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="5368001670-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>If a conditional match operator fails, the failed expression is matched against
│ │ │  the patterns in all clauses between the <code class="inline">else</code> and <code class="inline">end</code> keywords. If a match
│ │ │  succeeds and the optional guard sequence <code class="inline">GuardSeq</code> is true, the corresponding
│ │ │  <code class="inline">Body</code> is evaluated. The value returned from the body is the return value of the
│ │ │  <code class="inline">maybe</code> block.</p><p>If there is no matching pattern with a true guard sequence, an <code class="inline">else_clause</code>
│ │ │  run-time error occurs.</p><p>None of the variables bound in a <code class="inline">maybe</code> block must be used in the <code class="inline">else</code>
│ │ │  clauses. None of the variables bound in the <code class="inline">else</code> clauses must be used in the
│ │ │  code that follows the <code class="inline">maybe</code> block.</p><p>Here is the previous example augmented with <code class="inline">else</code> clauses:</p><pre><code class="makeup erlang" translate="no"><span class="k">maybe</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8962813683-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="8962813683-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="8962813683-2">(</span><span class="p" data-group-id="8962813683-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0468488107-1">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="0468488107-1">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">a</span><span class="p" data-group-id="0468488107-2">(</span><span class="p" data-group-id="0468488107-2">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8962813683-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="8962813683-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="8962813683-4">(</span><span class="p" data-group-id="8962813683-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0468488107-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="0468488107-3">}</span><span class="w"> </span><span class="o">?</span><span class="o">=</span><span class="w"> </span><span class="nf">b</span><span class="p" data-group-id="0468488107-4">(</span><span class="p" data-group-id="0468488107-4">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="w">
│ │ │  </span><span class="k">else</span><span class="w">
│ │ │      </span><span class="ss">error</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">error</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">wrong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">error</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>The <code class="inline">else</code> clauses translate the failing value from the conditional match
│ │ │  operators to the value <code class="inline">error</code>. If the failing value is not one of the
│ │ │  recognized values, a <code class="inline">else_clause</code> run-time error occurs.</p><h2 id="send" class="section-heading">
│ │ │ @@ -481,75 +481,75 @@
│ │ │  <code class="inline">{Name,Node}</code> (or a pid located at another node), also never fails.</li></ul><h2 id="receive" class="section-heading">
│ │ │    <a href="#receive" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Receive</span>
│ │ │  </h2>
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="3115281751-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="3115281751-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="3919113848-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="3919113848-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="3115281751-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="3115281751-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="3919113848-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="3919113848-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>Fetches a received message present in the message queue of the process. The
│ │ │  first message in the message queue is matched sequentially against the patterns
│ │ │  from top to bottom. If no match was found, the matching sequence is repeated for
│ │ │  the second message in the queue, and so on. Messages are queued in the
│ │ │  <a href="ref_man_processes.html#message-queue-order">order they were received</a>. If a match
│ │ │  succeeds, that is, if the <code class="inline">Pattern</code> matches and the optional guard sequence
│ │ │  <code class="inline">GuardSeq</code> is true, then the message is removed from the message queue and the
│ │ │  corresponding <code class="inline">Body</code> is evaluated. All other messages in the message queue
│ │ │  remain unchanged.</p><p>The return value of <code class="inline">Body</code> is the return value of the <code class="inline">receive</code> expression.</p><p><code class="inline">receive</code> never fails. The execution is suspended, possibly indefinitely, until
│ │ │  a message arrives that matches one of the patterns and with a true guard
│ │ │ -sequence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="4907776173-1">(</span><span class="p" data-group-id="4907776173-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +sequence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="5941663122-1">(</span><span class="p" data-group-id="5941663122-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">onhook</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">disconnect</span><span class="p" data-group-id="4907776173-2">(</span><span class="p" data-group-id="4907776173-2">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">idle</span><span class="p" data-group-id="4907776173-3">(</span><span class="p" data-group-id="4907776173-3">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4907776173-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="4907776173-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4907776173-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4907776173-6">(</span><span class="p" data-group-id="4907776173-6">)</span><span class="p" data-group-id="4907776173-5">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="4907776173-7">(</span><span class="p" data-group-id="4907776173-7">)</span><span class="w">
│ │ │ +            </span><span class="nf">disconnect</span><span class="p" data-group-id="5941663122-2">(</span><span class="p" data-group-id="5941663122-2">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">idle</span><span class="p" data-group-id="5941663122-3">(</span><span class="p" data-group-id="5941663122-3">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="5941663122-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="5941663122-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5941663122-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="5941663122-6">(</span><span class="p" data-group-id="5941663122-6">)</span><span class="p" data-group-id="5941663122-5">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="5941663122-7">(</span><span class="p" data-group-id="5941663122-7">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The <code class="inline">receive</code> expression can be augmented with a timeout:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="5172239022-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="5172239022-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="8527677539-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="8527677539-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="5172239022-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="5172239022-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="8527677539-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="8527677539-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │  </span><span class="k">after</span><span class="w">
│ │ │      </span><span class="n">ExprT</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyT</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p><code class="inline">receive...after</code> works exactly as <code class="inline">receive</code>, except that if no matching message
│ │ │  has arrived within <code class="inline">ExprT</code> milliseconds, then <code class="inline">BodyT</code> is evaluated instead. The
│ │ │  return value of <code class="inline">BodyT</code> then becomes the return value of the <code class="inline">receive...after</code>
│ │ │  expression. <code class="inline">ExprT</code> is to evaluate to an integer, or the atom <code class="inline">infinity</code>. The
│ │ │  allowed integer range is from 0 to 4294967295, that is, the longest possible
│ │ │  timeout is almost 50 days. With a zero value the timeout occurs immediately if
│ │ │  there is no matching message in the message queue.</p><p>The atom <code class="inline">infinity</code> will make the process wait indefinitely for a matching
│ │ │  message. This is the same as not using a timeout. It can be useful for timeout
│ │ │ -values that are calculated at runtime.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="9527063922-1">(</span><span class="p" data-group-id="9527063922-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +values that are calculated at runtime.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">wait_for_onhook</span><span class="p" data-group-id="0788670497-1">(</span><span class="p" data-group-id="0788670497-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">onhook</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">disconnect</span><span class="p" data-group-id="9527063922-2">(</span><span class="p" data-group-id="9527063922-2">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">idle</span><span class="p" data-group-id="9527063922-3">(</span><span class="p" data-group-id="9527063922-3">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="9527063922-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="9527063922-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9527063922-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="9527063922-6">(</span><span class="p" data-group-id="9527063922-6">)</span><span class="p" data-group-id="9527063922-5">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="9527063922-7">(</span><span class="p" data-group-id="9527063922-7">)</span><span class="w">
│ │ │ +            </span><span class="nf">disconnect</span><span class="p" data-group-id="0788670497-2">(</span><span class="p" data-group-id="0788670497-2">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">idle</span><span class="p" data-group-id="0788670497-3">(</span><span class="p" data-group-id="0788670497-3">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0788670497-4">{</span><span class="ss">connect</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="0788670497-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">B</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0788670497-5">{</span><span class="ss">busy</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0788670497-6">(</span><span class="p" data-group-id="0788670497-6">)</span><span class="p" data-group-id="0788670497-5">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">wait_for_onhook</span><span class="p" data-group-id="0788670497-7">(</span><span class="p" data-group-id="0788670497-7">)</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w">
│ │ │          </span><span class="mi">60000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">disconnect</span><span class="p" data-group-id="9527063922-8">(</span><span class="p" data-group-id="9527063922-8">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">error</span><span class="p" data-group-id="9527063922-9">(</span><span class="p" data-group-id="9527063922-9">)</span><span class="w">
│ │ │ +            </span><span class="nf">disconnect</span><span class="p" data-group-id="0788670497-8">(</span><span class="p" data-group-id="0788670497-8">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">error</span><span class="p" data-group-id="0788670497-9">(</span><span class="p" data-group-id="0788670497-9">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>It is legal to use a <code class="inline">receive...after</code> expression with no branches:</p><pre><code class="makeup erlang" translate="no"><span class="k">receive</span><span class="w">
│ │ │  </span><span class="k">after</span><span class="w">
│ │ │      </span><span class="n">ExprT</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyT</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>This construction does not consume any messages, only suspends execution in the
│ │ │ -process for <code class="inline">ExprT</code> milliseconds. This can be used to implement simple timers.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">timer</span><span class="p" data-group-id="6634657864-1">(</span><span class="p" data-group-id="6634657864-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="6634657864-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6634657864-3">[</span><span class="nf">self</span><span class="p" data-group-id="6634657864-4">(</span><span class="p" data-group-id="6634657864-4">)</span><span class="p" data-group-id="6634657864-3">]</span><span class="p" data-group-id="6634657864-2">)</span><span class="p">.</span><span class="w">
│ │ │ +process for <code class="inline">ExprT</code> milliseconds. This can be used to implement simple timers.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">timer</span><span class="p" data-group-id="2120595564-1">(</span><span class="p" data-group-id="2120595564-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="2120595564-2">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2120595564-3">[</span><span class="nf">self</span><span class="p" data-group-id="2120595564-4">(</span><span class="p" data-group-id="2120595564-4">)</span><span class="p" data-group-id="2120595564-3">]</span><span class="p" data-group-id="2120595564-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">timer</span><span class="p" data-group-id="6634657864-5">(</span><span class="n">Pid</span><span class="p" data-group-id="6634657864-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">timer</span><span class="p" data-group-id="2120595564-5">(</span><span class="n">Pid</span><span class="p" data-group-id="2120595564-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w">
│ │ │          </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">timeout</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>For more information on timers in Erlang in general, see the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/time_correction.html#timers"><em>Timers</em></a> section of the
│ │ │  <a href="../../erts-15.2.7.3/doc/html/time_correction.html"><em>Time and Time Correction in Erlang</em></a>
│ │ │ @@ -591,21 +591,21 @@
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │  4&gt; </span><span class="mf">0.0</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">-</span><span class="mf">0.0</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │  5&gt; </span><span class="mf">0.0</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">+</span><span class="mf">0.0</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │  6&gt; </span><span class="mi">1</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="p" data-group-id="6594113104-1">#{</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="6594113104-1">}</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="6594113104-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6594113104-2">}</span><span class="p">.</span><span class="w">
│ │ │ +7&gt; </span><span class="p" data-group-id="6559638315-1">#{</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="6559638315-1">}</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="6559638315-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6559638315-2">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ -8&gt; </span><span class="p" data-group-id="6594113104-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6594113104-3">}</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="p" data-group-id="6594113104-4">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">2.0</span><span class="p" data-group-id="6594113104-4">}</span><span class="p">.</span><span class="w">
│ │ │ +8&gt; </span><span class="p" data-group-id="6559638315-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6559638315-3">}</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="p" data-group-id="6559638315-4">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">2.0</span><span class="p" data-group-id="6559638315-4">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -9&gt; </span><span class="p" data-group-id="6594113104-5">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="6594113104-5">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="6594113104-6">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="6594113104-6">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +9&gt; </span><span class="p" data-group-id="6559638315-5">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="6559638315-5">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="6559638315-6">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="6559638315-6">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -10&gt; </span><span class="p" data-group-id="6594113104-7">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="6594113104-7">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="6594113104-8">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="6594113104-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +10&gt; </span><span class="p" data-group-id="6559638315-7">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">2</span><span class="p" data-group-id="6559638315-7">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="p" data-group-id="6559638315-8">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="6559638315-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Prior to OTP 27, the term equivalence operators considered <code class="inline">0.0</code>
│ │ │  and <code class="inline">-0.0</code> to be the same term.</p><p>This was changed in OTP 27 but legacy code may have expected them to be
│ │ │  considered the same. To help users catch errors that may arise from an
│ │ │  upgrade, the compiler raises a warning when <code class="inline">0.0</code> is pattern-matched or used
│ │ │  in a term equivalence test.</p><p>If you need to match <code class="inline">0.0</code> specifically, the warning can be silenced by
│ │ │  writing <code class="inline">+0.0</code> instead, which produces the same term but makes the compiler
│ │ │  interpret the match as being done on purpose.</p></section><h2 id="arithmetic-expressions" class="section-heading">
│ │ │ @@ -631,15 +631,15 @@
│ │ │  </span><span class="mi">0</span><span class="gp unselectable">
│ │ │  8&gt; </span><span class="mi">2#10</span><span class="w"> </span><span class="ow">bor</span><span class="w"> </span><span class="mi">2#01</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │  9&gt; </span><span class="ss">a</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">10</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: an error occurred when evaluating an arithmetic expression
│ │ │       in operator  +/2
│ │ │          called as a + 10</span><span class="gp unselectable">
│ │ │ -10&gt; </span><span class="mi">1</span><span class="w"> </span><span class="nf">bsl</span><span class="w"> </span><span class="p" data-group-id="6336316787-1">(</span><span class="mi">1</span><span class="w"> </span><span class="ow">bsl</span><span class="w"> </span><span class="mi">64</span><span class="p" data-group-id="6336316787-1">)</span><span class="p">.</span><span class="w">
│ │ │ +10&gt; </span><span class="mi">1</span><span class="w"> </span><span class="nf">bsl</span><span class="w"> </span><span class="p" data-group-id="1392423137-1">(</span><span class="mi">1</span><span class="w"> </span><span class="ow">bsl</span><span class="w"> </span><span class="mi">64</span><span class="p" data-group-id="1392423137-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: a system limit has been reached
│ │ │       in operator  bsl/2
│ │ │          called as 1 bsl 18446744073709551616</span></code></pre><h2 id="boolean-expressions" class="section-heading">
│ │ │    <a href="#boolean-expressions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Boolean Expressions</span>
│ │ │ @@ -658,136 +658,136 @@
│ │ │    <a href="#short-circuit-expressions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Short-Circuit Expressions</span>
│ │ │  </h2>
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="n">Expr1</span><span class="w"> </span><span class="ow">orelse</span><span class="w"> </span><span class="n">Expr2</span><span class="w">
│ │ │  </span><span class="n">Expr1</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">Expr2</span></code></pre><p><code class="inline">Expr2</code> is evaluated only if necessary. That is, <code class="inline">Expr2</code> is evaluated only if:</p><ul><li><code class="inline">Expr1</code> evaluates to <code class="inline">false</code> in an <code class="inline">orelse</code> expression.</li></ul><p>or</p><ul><li><code class="inline">Expr1</code> evaluates to <code class="inline">true</code> in an <code class="inline">andalso</code> expression.</li></ul><p>Returns either the value of <code class="inline">Expr1</code> (that is, <code class="inline">true</code> or <code class="inline">false</code>) or the value of
│ │ │ -<code class="inline">Expr2</code> (if <code class="inline">Expr2</code> is evaluated).</p><p><em>Example 1:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="o">-</span><span class="mf">1.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nc">math</span><span class="p">:</span><span class="nf">sqrt</span><span class="p" data-group-id="3587349188-1">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="3587349188-1">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="k">of</span></code></pre><p>This works even if <code class="inline">A</code> is less than <code class="inline">-1.0</code>, since in that case, <a href="../../lib/stdlib-6.2.2.2/doc/html/math.html#sqrt/1"><code class="inline">math:sqrt/1</code></a> is
│ │ │ -never evaluated.</p><p><em>Example 2:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">OnlyOne</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">is_atom</span><span class="p" data-group-id="2872149257-1">(</span><span class="n">L</span><span class="p" data-group-id="2872149257-1">)</span><span class="w"> </span><span class="nf">orelse</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="2872149257-2">(</span><span class="nf">is_list</span><span class="p" data-group-id="2872149257-3">(</span><span class="n">L</span><span class="p" data-group-id="2872149257-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="2872149257-4">(</span><span class="n">L</span><span class="p" data-group-id="2872149257-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="2872149257-2">)</span><span class="p">,</span></code></pre><p><code class="inline">Expr2</code> is not required to evaluate to a Boolean value. Because of that,
│ │ │ -<code class="inline">andalso</code> and <code class="inline">orelse</code> are tail-recursive.</p><p><em>Example 3 (tail-recursive function):</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="7206868615-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7206868615-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="7206868615-2">]</span><span class="p" data-group-id="7206868615-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Pred</span><span class="p" data-group-id="7206868615-3">(</span><span class="n">Hd</span><span class="p" data-group-id="7206868615-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">all</span><span class="p" data-group-id="7206868615-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="7206868615-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">all</span><span class="p" data-group-id="7206868615-5">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7206868615-6">[</span><span class="p" data-group-id="7206868615-6">]</span><span class="p" data-group-id="7206868615-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +<code class="inline">Expr2</code> (if <code class="inline">Expr2</code> is evaluated).</p><p><em>Example 1:</em></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="o">-</span><span class="mf">1.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nc">math</span><span class="p">:</span><span class="nf">sqrt</span><span class="p" data-group-id="4026545721-1">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="4026545721-1">)</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="k">of</span></code></pre><p>This works even if <code class="inline">A</code> is less than <code class="inline">-1.0</code>, since in that case, <a href="../../lib/stdlib-6.2.2.2/doc/html/math.html#sqrt/1"><code class="inline">math:sqrt/1</code></a> is
│ │ │ +never evaluated.</p><p><em>Example 2:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">OnlyOne</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">is_atom</span><span class="p" data-group-id="2479355308-1">(</span><span class="n">L</span><span class="p" data-group-id="2479355308-1">)</span><span class="w"> </span><span class="nf">orelse</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="2479355308-2">(</span><span class="nf">is_list</span><span class="p" data-group-id="2479355308-3">(</span><span class="n">L</span><span class="p" data-group-id="2479355308-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="2479355308-4">(</span><span class="n">L</span><span class="p" data-group-id="2479355308-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="2479355308-2">)</span><span class="p">,</span></code></pre><p><code class="inline">Expr2</code> is not required to evaluate to a Boolean value. Because of that,
│ │ │ +<code class="inline">andalso</code> and <code class="inline">orelse</code> are tail-recursive.</p><p><em>Example 3 (tail-recursive function):</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="5754579008-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5754579008-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="5754579008-2">]</span><span class="p" data-group-id="5754579008-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pred</span><span class="p" data-group-id="5754579008-3">(</span><span class="n">Hd</span><span class="p" data-group-id="5754579008-3">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">all</span><span class="p" data-group-id="5754579008-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="5754579008-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">all</span><span class="p" data-group-id="5754579008-5">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5754579008-6">[</span><span class="p" data-group-id="5754579008-6">]</span><span class="p" data-group-id="5754579008-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">true</span><span class="p">.</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP R13A, <code class="inline">Expr2</code> was required to evaluate to a Boolean value,
│ │ │  and as consequence, <code class="inline">andalso</code> and <code class="inline">orelse</code> were <strong>not</strong> tail-recursive.</p></section><h2 id="list-operations" class="section-heading">
│ │ │    <a href="#list-operations" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">List Operations</span>
│ │ │  </h2>
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="n">Expr1</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">Expr2</span><span class="w">
│ │ │  </span><span class="n">Expr1</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="n">Expr2</span></code></pre><p>The list concatenation operator <code class="inline">++</code> appends its second argument to its first
│ │ │  and returns the resulting list.</p><p>The list subtraction operator <code class="inline">--</code> produces a list that is a copy of the first
│ │ │  argument. The procedure is as follows: for each element in the second argument,
│ │ │ -the first occurrence of this element (if any) is removed.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0009806239-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0009806239-1">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="0009806239-2">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="0009806239-2">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0009806239-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="0009806239-3">]</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="0009806239-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0009806239-4">]</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="p" data-group-id="0009806239-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0009806239-5">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0009806239-6">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0009806239-6">]</span></code></pre><h2 id="map-expressions" class="section-heading">
│ │ │ +the first occurrence of this element (if any) is removed.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7863981655-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7863981655-1">]</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="7863981655-2">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7863981655-2">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7863981655-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7863981655-3">]</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="7863981655-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7863981655-4">]</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="p" data-group-id="7863981655-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7863981655-5">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7863981655-6">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7863981655-6">]</span></code></pre><h2 id="map-expressions" class="section-heading">
│ │ │    <a href="#map-expressions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Map Expressions</span>
│ │ │  </h2>
│ │ │  <h3 id="creating-maps" class="section-heading">
│ │ │    <a href="#creating-maps" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Creating Maps</span>
│ │ │  </h3>
│ │ │  <p>Constructing a new map is done by letting an expression <code class="inline">K</code> be associated with
│ │ │ -another expression <code class="inline">V</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8750076825-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="8750076825-1">}</span></code></pre><p>New maps can include multiple associations at construction by listing every
│ │ │ -association:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4516984199-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="4516984199-1">}</span></code></pre><p>An empty map is constructed by not associating any terms with each other:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7291422652-1">#{</span><span class="p" data-group-id="7291422652-1">}</span></code></pre><p>All keys and values in the map are terms. Any expression is first evaluated and
│ │ │ +another expression <code class="inline">V</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2519021523-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="2519021523-1">}</span></code></pre><p>New maps can include multiple associations at construction by listing every
│ │ │ +association:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0412751782-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="0412751782-1">}</span></code></pre><p>An empty map is constructed by not associating any terms with each other:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7717527478-1">#{</span><span class="p" data-group-id="7717527478-1">}</span></code></pre><p>All keys and values in the map are terms. Any expression is first evaluated and
│ │ │  then the resulting terms are used as <em>key</em> and <em>value</em> respectively.</p><p>Keys and values are separated by the <code class="inline">=&gt;</code> arrow and associations are separated
│ │ │ -by a comma (<code class="inline">,</code>).</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6940796617-1">#{</span><span class="p" data-group-id="6940796617-1">}</span><span class="p">,</span><span class="w">                 </span><span class="c1">% empty map</span><span class="w">
│ │ │ -</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6940796617-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6940796617-3">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="6940796617-3">&gt;&gt;</span><span class="p" data-group-id="6940796617-2">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% single association with literals</span><span class="w">
│ │ │ -</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6940796617-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6940796617-4">}</span><span class="p">,</span><span class="w">   </span><span class="c1">% multiple associations with literals</span><span class="w">
│ │ │ -</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6940796617-5">#{</span><span class="ss">k</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6940796617-6">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="6940796617-6">}</span><span class="p" data-group-id="6940796617-5">}</span><span class="p">,</span><span class="w">       </span><span class="c1">% single association with variables</span><span class="w">
│ │ │ -</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6940796617-7">#{</span><span class="p" data-group-id="6940796617-8">{</span><span class="s">&quot;w&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="6940796617-8">}</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="6940796617-9">(</span><span class="p" data-group-id="6940796617-9">)</span><span class="p" data-group-id="6940796617-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% compound key associated with an evaluated expression</span></code></pre><p>Here, <code class="inline">A</code> and <code class="inline">B</code> are any expressions and <code class="inline">M0</code> through <code class="inline">M4</code> are the resulting
│ │ │ -map terms.</p><p>If two matching keys are declared, the latter key takes precedence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3246055021-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="3246055021-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3246055021-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p" data-group-id="3246055021-2">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="3246055021-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="3246055021-3">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3246055021-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="3246055021-4">}</span></code></pre><p>The order in which the expressions constructing the keys (and their associated
│ │ │ +by a comma (<code class="inline">,</code>).</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2829239521-1">#{</span><span class="p" data-group-id="2829239521-1">}</span><span class="p">,</span><span class="w">                 </span><span class="c1">% empty map</span><span class="w">
│ │ │ +</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2829239521-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2829239521-3">&lt;&lt;</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="2829239521-3">&gt;&gt;</span><span class="p" data-group-id="2829239521-2">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% single association with literals</span><span class="w">
│ │ │ +</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2829239521-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="2829239521-4">}</span><span class="p">,</span><span class="w">   </span><span class="c1">% multiple associations with literals</span><span class="w">
│ │ │ +</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2829239521-5">#{</span><span class="ss">k</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2829239521-6">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="2829239521-6">}</span><span class="p" data-group-id="2829239521-5">}</span><span class="p">,</span><span class="w">       </span><span class="c1">% single association with variables</span><span class="w">
│ │ │ +</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2829239521-7">#{</span><span class="p" data-group-id="2829239521-8">{</span><span class="s">&quot;w&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="2829239521-8">}</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="2829239521-9">(</span><span class="p" data-group-id="2829239521-9">)</span><span class="p" data-group-id="2829239521-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% compound key associated with an evaluated expression</span></code></pre><p>Here, <code class="inline">A</code> and <code class="inline">B</code> are any expressions and <code class="inline">M0</code> through <code class="inline">M4</code> are the resulting
│ │ │ +map terms.</p><p>If two matching keys are declared, the latter key takes precedence.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="1233870937-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="1233870937-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1233870937-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p" data-group-id="1233870937-2">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="1233870937-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="1233870937-3">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1233870937-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="1233870937-4">}</span></code></pre><p>The order in which the expressions constructing the keys (and their associated
│ │ │  values) are evaluated is not defined. The syntactic order of the key-value pairs
│ │ │  in the construction is of no relevance, except in the recently mentioned case of
│ │ │  two matching keys.</p><h3 id="updating-maps" class="section-heading">
│ │ │    <a href="#updating-maps" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Updating Maps</span>
│ │ │  </h3>
│ │ │  <p>Updating a map has a similar syntax as constructing it.</p><p>An expression defining the map to be updated is put in front of the expression
│ │ │ -defining the keys to be updated and their respective values:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="3349125292-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="3349125292-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map and <code class="inline">K</code> and <code class="inline">V</code> are any expression.</p><p>If key <code class="inline">K</code> does not match any existing key in the map, a new association is
│ │ │ +defining the keys to be updated and their respective values:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="3837975082-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="3837975082-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map and <code class="inline">K</code> and <code class="inline">V</code> are any expression.</p><p>If key <code class="inline">K</code> does not match any existing key in the map, a new association is
│ │ │  created from key <code class="inline">K</code> to value <code class="inline">V</code>.</p><p>If key <code class="inline">K</code> matches an existing key in map <code class="inline">M</code>, its associated value is replaced
│ │ │  by the new value <code class="inline">V</code>. In both cases, the evaluated map expression returns a new
│ │ │ -map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p>To only update an existing value, the following syntax is used:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="7811926463-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="7811926463-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map, <code class="inline">V</code> is an expression and <code class="inline">K</code> is an expression
│ │ │ +map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p>To only update an existing value, the following syntax is used:</p><pre><code class="makeup erlang" translate="no"><span class="n">M</span><span class="p" data-group-id="3545426103-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="3545426103-1">}</span></code></pre><p>Here <code class="inline">M</code> is a term of type map, <code class="inline">V</code> is an expression and <code class="inline">K</code> is an expression
│ │ │  that evaluates to an existing key in <code class="inline">M</code>.</p><p>If key <code class="inline">K</code> does not match any existing keys in map <code class="inline">M</code>, an exception of type
│ │ │  <code class="inline">badkey</code> is raised at runtime. If a matching key <code class="inline">K</code> is present in map <code class="inline">M</code>,
│ │ │  its associated value is replaced by the new value <code class="inline">V</code>, and the evaluated map
│ │ │ -expression returns a new map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3429409929-1">#{</span><span class="p" data-group-id="3429409929-1">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M0</span><span class="p" data-group-id="3429409929-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3429409929-2">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="3429409929-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3429409929-3">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M2</span><span class="p" data-group-id="3429409929-4">#{</span><span class="s">&quot;function&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3429409929-5">(</span><span class="p" data-group-id="3429409929-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="3429409929-6">(</span><span class="p" data-group-id="3429409929-6">)</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="3429409929-4">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M3</span><span class="p" data-group-id="3429409929-7">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="3429409929-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% &#39;a&#39; and &#39;b&#39; was added in `M1` and `M2`.</span></code></pre><p>Here <code class="inline">M0</code> is any map. It follows that <code class="inline">M1</code> through <code class="inline">M4</code> are maps as well.</p><p><em>More examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6019702084-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="6019702084-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6019702084-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="p" data-group-id="6019702084-2">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="n">M</span><span class="p" data-group-id="6019702084-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6019702084-3">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6019702084-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6019702084-4">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="n">M</span><span class="p" data-group-id="6019702084-5">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6019702084-5">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6019702084-6">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6019702084-6">}</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="n">M</span><span class="p" data-group-id="6019702084-7">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6019702084-7">}</span><span class="p">.</span><span class="w">
│ │ │ +expression returns a new map.</p><p>If <code class="inline">M</code> is not of type map, an exception of type <code class="inline">badmap</code> is raised.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="n">M0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8233043139-1">#{</span><span class="p" data-group-id="8233043139-1">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">M1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M0</span><span class="p" data-group-id="8233043139-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="8233043139-2">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">M2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M1</span><span class="p" data-group-id="8233043139-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="8233043139-3">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">M3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M2</span><span class="p" data-group-id="8233043139-4">#{</span><span class="s">&quot;function&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="8233043139-5">(</span><span class="p" data-group-id="8233043139-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="8233043139-6">(</span><span class="p" data-group-id="8233043139-6">)</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="8233043139-4">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">M4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M3</span><span class="p" data-group-id="8233043139-7">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="8233043139-7">}</span><span class="p">.</span><span class="w">  </span><span class="c1">% &#39;a&#39; and &#39;b&#39; was added in `M1` and `M2`.</span></code></pre><p>Here <code class="inline">M0</code> is any map. It follows that <code class="inline">M1</code> through <code class="inline">M4</code> are maps as well.</p><p><em>More examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6655198208-1">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p" data-group-id="6655198208-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6655198208-2">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="p" data-group-id="6655198208-2">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="n">M</span><span class="p" data-group-id="6655198208-3">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6655198208-3">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6655198208-4">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6655198208-4">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ +3&gt; </span><span class="n">M</span><span class="p" data-group-id="6655198208-5">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6655198208-5">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6655198208-6">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6655198208-6">}</span><span class="gp unselectable">
│ │ │ +4&gt; </span><span class="n">M</span><span class="p" data-group-id="6655198208-7">#{</span><span class="mf">1.0</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="6655198208-7">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: bad argument</span></code></pre><p>As in construction, the order in which the key and value expressions are
│ │ │  evaluated is not defined. The syntactic order of the key-value pairs in the
│ │ │  update is of no relevance, except in the case where two keys match. In that
│ │ │  case, the latter value is used.</p><h3 id="maps-in-patterns" class="section-heading">
│ │ │    <a href="#maps-in-patterns" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Maps in Patterns</span>
│ │ │  </h3>
│ │ │ -<p>Matching of key-value associations from maps is done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1899455719-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="1899455719-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here <code class="inline">M</code> is any map. The key <code class="inline">K</code> must be a
│ │ │ +<p>Matching of key-value associations from maps is done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8355857259-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="8355857259-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here <code class="inline">M</code> is any map. The key <code class="inline">K</code> must be a
│ │ │  <a href="expressions.html#guard-expressions">guard expression</a>, with all variables already
│ │ │  bound. <code class="inline">V</code> can be any pattern with either bound or unbound variables.</p><p>If the variable <code class="inline">V</code> is unbound, it becomes bound to the value associated with
│ │ │  the key <code class="inline">K</code>, which must exist in the map <code class="inline">M</code>. If the variable <code class="inline">V</code> is bound, it
│ │ │  must match the value associated with <code class="inline">K</code> in <code class="inline">M</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 23, the expression defining the key <code class="inline">K</code> was restricted to be
│ │ │ -either a single variable or a literal.</p></section><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5065101631-1">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5065101631-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5065101631-2">}</span><span class="p" data-group-id="5065101631-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5065101631-3">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5065101631-4">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5065101631-4">}</span><span class="p" data-group-id="5065101631-3">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="5065101631-5">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="5065101631-6">{</span><span class="mi">1</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="5065101631-6">}</span><span class="p" data-group-id="5065101631-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5065101631-7">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5065101631-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5065101631-8">}</span><span class="p" data-group-id="5065101631-7">}</span><span class="gp unselectable">
│ │ │ +either a single variable or a literal.</p></section><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6520977354-1">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6520977354-2">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6520977354-2">}</span><span class="p" data-group-id="6520977354-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6520977354-3">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6520977354-4">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6520977354-4">}</span><span class="p" data-group-id="6520977354-3">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="6520977354-5">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6520977354-6">{</span><span class="mi">1</span><span class="p">,</span><span class="n">B</span><span class="p" data-group-id="6520977354-6">}</span><span class="p" data-group-id="6520977354-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6520977354-7">#{</span><span class="s">&quot;tuple&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6520977354-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6520977354-8">}</span><span class="p" data-group-id="6520977354-7">}</span><span class="gp unselectable">
│ │ │  3&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">2</span><span class="p">.</span></code></pre><p>This binds variable <code class="inline">B</code> to integer <code class="inline">2</code>.</p><p>Similarly, multiple values from the map can be matched:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1497543939-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="1497543939-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here keys <code class="inline">K1</code> through <code class="inline">Kn</code> are any expressions with literals or bound
│ │ │ +</span><span class="mi">2</span><span class="p">.</span></code></pre><p>This binds variable <code class="inline">B</code> to integer <code class="inline">2</code>.</p><p>Similarly, multiple values from the map can be matched:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2044930997-1">#{</span><span class="n">K1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Kn</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Vn</span><span class="p" data-group-id="2044930997-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>Here keys <code class="inline">K1</code> through <code class="inline">Kn</code> are any expressions with literals or bound
│ │ │  variables. If all key expressions evaluate successfully and all keys
│ │ │  exist in map <code class="inline">M</code>, all variables in <code class="inline">V1 .. Vn</code> is matched to the
│ │ │  associated values of their respective keys.</p><p>If the matching conditions are not met the match fails.</p><p>Note that when matching a map, only the <code class="inline">:=</code> operator (not the <code class="inline">=&gt;</code>) is allowed
│ │ │  as a delimiter for the associations.</p><p>The order in which keys are declared in matching has no relevance.</p><p>Duplicate keys are allowed in matching and match each pattern associated to the
│ │ │ -keys:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0758638438-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V2</span><span class="p" data-group-id="0758638438-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>The empty map literal (<code class="inline">#{}</code>) matches any map when used as a pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8674754916-1">#{</span><span class="p" data-group-id="8674754916-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>This expression matches if the expression <code class="inline">Expr</code> is of type map, otherwise it
│ │ │ -fails with an exception <code class="inline">badmatch</code>.</p><p>Here the key to be retrieved is constructed from an expression:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6304598535-1">#{</span><span class="p" data-group-id="6304598535-2">{</span><span class="ss">tag</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="6304598535-3">(</span><span class="n">List</span><span class="p" data-group-id="6304598535-3">)</span><span class="p" data-group-id="6304598535-2">}</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="6304598535-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map</span></code></pre><p><code class="inline">List</code> must be an already bound variable.</p><h4>Matching Syntax</h4><p>Matching of literals as keys are allowed in function heads:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% only start if not_started</span><span class="w">
│ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="9961049473-1">(</span><span class="ss">start</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9961049473-2">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">not_started</span><span class="p" data-group-id="9961049473-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="9961049473-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +keys:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9516982293-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V2</span><span class="p" data-group-id="9516982293-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span></code></pre><p>The empty map literal (<code class="inline">#{}</code>) matches any map when used as a pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2870227116-1">#{</span><span class="p" data-group-id="2870227116-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>This expression matches if the expression <code class="inline">Expr</code> is of type map, otherwise it
│ │ │ +fails with an exception <code class="inline">badmatch</code>.</p><p>Here the key to be retrieved is constructed from an expression:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5478405356-1">#{</span><span class="p" data-group-id="5478405356-2">{</span><span class="ss">tag</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="5478405356-3">(</span><span class="n">List</span><span class="p" data-group-id="5478405356-3">)</span><span class="p" data-group-id="5478405356-2">}</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="p" data-group-id="5478405356-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map</span></code></pre><p><code class="inline">List</code> must be an already bound variable.</p><h4>Matching Syntax</h4><p>Matching of literals as keys are allowed in function heads:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% only start if not_started</span><span class="w">
│ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="8257920478-1">(</span><span class="ss">start</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8257920478-2">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">not_started</span><span class="p" data-group-id="8257920478-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8257920478-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9961049473-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="9961049473-4">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="9961049473-4">}</span><span class="p" data-group-id="9961049473-3">}</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8257920478-3">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8257920478-4">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="8257920478-4">}</span><span class="p" data-group-id="8257920478-3">}</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% only change if started</span><span class="w">
│ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="9961049473-5">(</span><span class="ss">change</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9961049473-6">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="9961049473-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="9961049473-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="8257920478-5">(</span><span class="ss">change</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8257920478-6">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">start</span><span class="p" data-group-id="8257920478-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8257920478-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9961049473-7">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="9961049473-8">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">changed</span><span class="p" data-group-id="9961049473-8">}</span><span class="p" data-group-id="9961049473-7">}</span><span class="p">;</span></code></pre><h3 id="maps-in-guards" class="section-heading">
│ │ │ +    </span><span class="p" data-group-id="8257920478-7">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">S</span><span class="p" data-group-id="8257920478-8">#{</span><span class="ss">state</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">changed</span><span class="p" data-group-id="8257920478-8">}</span><span class="p" data-group-id="8257920478-7">}</span><span class="p">;</span></code></pre><h3 id="maps-in-guards" class="section-heading">
│ │ │    <a href="#maps-in-guards" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Maps in Guards</span>
│ │ │  </h3>
│ │ │  <p>Maps are allowed in guards as long as all subexpressions are valid guard
│ │ │  expressions.</p><p>The following guard BIFs handle maps:</p><ul><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#is_map/1">is_map/1</a> in the <code class="inline">erlang</code> module</li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#is_map_key/2">is_map_key/2</a> in the <code class="inline">erlang</code> module</li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#map_get/2">map_get/2</a> in the <code class="inline">erlang</code> module</li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#map_size/1">map_size/1</a> in the <code class="inline">erlang</code> module</li></ul><h2 id="bit-syntax-expressions" class="section-heading">
│ │ │    <a href="#bit-syntax-expressions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Bit Syntax Expressions</span>
│ │ │  </h2>
│ │ │  <p>The bit syntax operates on <em>bit strings</em>. A bit string is a sequence of bits
│ │ │ -ordered from the most significant bit to the least significant bit.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5142037270-1">&lt;&lt;</span><span class="p" data-group-id="5142037270-1">&gt;&gt;</span><span class="w">  </span><span class="c1">% The empty bit string, zero length</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5142037270-2">&lt;&lt;</span><span class="n">E1</span><span class="p" data-group-id="5142037270-2">&gt;&gt;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5142037270-3">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">En</span><span class="p" data-group-id="5142037270-3">&gt;&gt;</span></code></pre><p>Each element <code class="inline">Ei</code> specifies a <em>segment</em> of the bit string. The segments are
│ │ │ +ordered from the most significant bit to the least significant bit.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8815291758-1">&lt;&lt;</span><span class="p" data-group-id="8815291758-1">&gt;&gt;</span><span class="w">  </span><span class="c1">% The empty bit string, zero length</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8815291758-2">&lt;&lt;</span><span class="n">E1</span><span class="p" data-group-id="8815291758-2">&gt;&gt;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8815291758-3">&lt;&lt;</span><span class="n">E1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">En</span><span class="p" data-group-id="8815291758-3">&gt;&gt;</span></code></pre><p>Each element <code class="inline">Ei</code> specifies a <em>segment</em> of the bit string. The segments are
│ │ │  ordered left to right from the most significant bit to the least significant bit
│ │ │  of the bit string.</p><p>Each segment specification <code class="inline">Ei</code> is a value, whose default type is <code class="inline">integer</code>,
│ │ │  followed by an optional <em>size expression</em> and an optional <em>type specifier list</em>.</p><pre><code class="makeup erlang" translate="no"><span class="n">Ei</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Value</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │       </span><span class="n">Value</span><span class="p">:</span><span class="n">Size</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │       </span><span class="n">Value</span><span class="o">/</span><span class="n">TypeSpecifierList</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │       </span><span class="n">Value</span><span class="p">:</span><span class="n">Size</span><span class="o">/</span><span class="n">TypeSpecifierList</span></code></pre><p>When used in a bit string construction, <code class="inline">Value</code> is an expression that is to
│ │ │  evaluate to an integer, float, or bit string. If the expression is not a single
│ │ │ @@ -798,34 +798,34 @@
│ │ │  <a href="expressions.html#guard-expressions">guard expression</a> that evaluates to an
│ │ │  integer. All variables in the guard expression must be already bound.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 23, <code class="inline">Size</code> was restricted to be an integer or a variable
│ │ │  bound to an integer.</p></section><p>The value of <code class="inline">Size</code> specifies the size of the segment in units (see below). The
│ │ │  default value depends on the type (see below):</p><ul><li>For <code class="inline">integer</code> it is 8.</li><li>For <code class="inline">float</code> it is 64.</li><li>For <code class="inline">binary</code> and <code class="inline">bitstring</code> it is the whole binary or bit string.</li></ul><p>In matching, the default value for a binary or bit string segment is only valid
│ │ │  for the last element. All other bit string or binary elements in the matching
│ │ │  must have a size specification.</p><p><a href="" id="binaries"></a></p><p><strong>Binaries</strong></p><p>A bit string with a length that is a multiple of 8 bits is known as a <em>binary</em>,
│ │ │  which is the most common and useful type of bit string.</p><p>A binary has a canonical representation in memory. Here follows a sequence of
│ │ │ -bytes where each byte's value is its sequence number:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2510065641-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p" data-group-id="2510065641-1">&gt;&gt;</span></code></pre><p>Bit strings are a later generalization of binaries, so many texts and much
│ │ │ -information about binaries apply just as well for bit strings.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3490065635-1">&lt;&lt;</span><span class="n">A</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3490065635-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3490065635-2">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="3490065635-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +bytes where each byte's value is its sequence number:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0188724809-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">9</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p" data-group-id="0188724809-1">&gt;&gt;</span></code></pre><p>Bit strings are a later generalization of binaries, so many texts and much
│ │ │ +information about binaries apply just as well for bit strings.</p><p><strong>Example:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4870624911-1">&lt;&lt;</span><span class="n">A</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4870624911-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4870624911-2">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="4870624911-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">* 1:3: a binary field without size is only allowed at the end of a binary pattern</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="3490065635-3">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">3</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3490065635-3">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3490065635-4">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="3490065635-4">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3490065635-5">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="3490065635-5">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="4870624911-3">&lt;&lt;</span><span class="n">A</span><span class="p">:</span><span class="mi">3</span><span class="o">/</span><span class="ss">binary</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="4870624911-3">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4870624911-4">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="4870624911-4">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4870624911-5">&lt;&lt;</span><span class="s">&quot;abcde&quot;</span><span class="p" data-group-id="4870624911-5">&gt;&gt;</span><span class="gp unselectable">
│ │ │  3&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3490065635-6">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3490065635-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +</span><span class="p" data-group-id="4870624911-6">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="4870624911-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │  4&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3490065635-7">&lt;&lt;</span><span class="s">&quot;de&quot;</span><span class="p" data-group-id="3490065635-7">&gt;&gt;</span></code></pre><p>For the <code class="inline">utf8</code>, <code class="inline">utf16</code>, and <code class="inline">utf32</code> types, <code class="inline">Size</code> must not be given. The size
│ │ │ +</span><span class="p" data-group-id="4870624911-7">&lt;&lt;</span><span class="s">&quot;de&quot;</span><span class="p" data-group-id="4870624911-7">&gt;&gt;</span></code></pre><p>For the <code class="inline">utf8</code>, <code class="inline">utf16</code>, and <code class="inline">utf32</code> types, <code class="inline">Size</code> must not be given. The size
│ │ │  of the segment is implicitly determined by the type and value itself.</p><p><code class="inline">TypeSpecifierList</code> is a list of type specifiers, in any order, separated by
│ │ │  hyphens (-). Default values are used for any omitted type specifiers.</p><ul><li><p><strong><code class="inline">Type</code>= <code class="inline">integer</code> | <code class="inline">float</code> | <code class="inline">binary</code> | <code class="inline">bytes</code> | <code class="inline">bitstring</code> | <code class="inline">bits</code> |
│ │ │  <code class="inline">utf8</code> | <code class="inline">utf16</code> | <code class="inline">utf32</code></strong> - The default is <code class="inline">integer</code>. <code class="inline">bytes</code> is a
│ │ │  shorthand for <code class="inline">binary</code> and <code class="inline">bits</code> is a shorthand for <code class="inline">bitstring</code>. See below
│ │ │  for more information about the <code class="inline">utf</code> types.</p></li><li><p><strong><code class="inline">Signedness</code>= <code class="inline">signed</code> | <code class="inline">unsigned</code></strong> - Only matters for matching and when
│ │ │  the type is <code class="inline">integer</code>. The default is <code class="inline">unsigned</code>.</p></li><li><p><strong><code class="inline">Endianness</code>= <code class="inline">big</code> | <code class="inline">little</code> | <code class="inline">native</code></strong> - Specifies byte level (octet
│ │ │  level) endianness (byte order). Native-endian means that the endianness is
│ │ │  resolved at load time to be either big-endian or little-endian, depending on
│ │ │  what is native for the CPU that the Erlang machine is run on. Endianness only
│ │ │  matters when the <strong>Type</strong> is either <code class="inline">integer</code>, <code class="inline">utf16</code>, <code class="inline">utf32</code>, or <code class="inline">float</code>. The
│ │ │ -default is <code class="inline">big</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4332411359-1">&lt;&lt;</span><span class="mi">16#1234</span><span class="p">:</span><span class="mi">16</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="4332411359-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4332411359-2">&lt;&lt;</span><span class="mi">16#3412</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="4332411359-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4332411359-3">&lt;&lt;</span><span class="mi">16#34</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">16#12</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="4332411359-3">&gt;&gt;</span></code></pre></li><li><p><strong><code class="inline">Unit</code>= <code class="inline">unit:IntegerLiteral</code></strong> - The allowed range is 1 through 256.
│ │ │ +default is <code class="inline">big</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1405524617-1">&lt;&lt;</span><span class="mi">16#1234</span><span class="p">:</span><span class="mi">16</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="1405524617-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1405524617-2">&lt;&lt;</span><span class="mi">16#3412</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="1405524617-2">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1405524617-3">&lt;&lt;</span><span class="mi">16#34</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="w"> </span><span class="mi">16#12</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="1405524617-3">&gt;&gt;</span></code></pre></li><li><p><strong><code class="inline">Unit</code>= <code class="inline">unit:IntegerLiteral</code></strong> - The allowed range is 1 through 256.
│ │ │  Defaults to 1 for <code class="inline">integer</code>, <code class="inline">float</code>, and <code class="inline">bitstring</code>, and to 8 for <code class="inline">binary</code>.
│ │ │  For types <code class="inline">bitstring</code>, <code class="inline">bits</code>, and <code class="inline">bytes</code>, it is not allowed to specify a
│ │ │  unit value different from the default value. No unit specifier must be given
│ │ │  for the types <code class="inline">utf8</code>, <code class="inline">utf16</code>, and <code class="inline">utf32</code>.</p></li></ul><h3 id="integer-segments" class="section-heading">
│ │ │    <a href="#integer-segments" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -850,41 +850,41 @@
│ │ │    </a>
│ │ │    <span class="text">Binary segments</span>
│ │ │  </h3>
│ │ │  <p>In this section, the phrase &quot;binary segment&quot; refers to any one of the segment
│ │ │  types <code class="inline">binary</code>, <code class="inline">bitstring</code>, <code class="inline">bytes</code>, and <code class="inline">bits</code>.</p><p>See also the paragraphs about <a href="expressions.html#binaries">Binaries</a>.</p><p>When constructing binaries and no size is specified for a binary segment, the
│ │ │  entire binary value is interpolated into the binary being constructed. However,
│ │ │  the size in bits of the binary being interpolated must be evenly divisible by
│ │ │ -the unit value for the segment; otherwise an exception is raised.</p><p>For example, the following examples all succeed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7664939151-1">&lt;&lt;</span><span class="p" data-group-id="7664939151-2">(</span><span class="p" data-group-id="7664939151-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7664939151-3">&gt;&gt;</span><span class="p" data-group-id="7664939151-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="7664939151-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7664939151-4">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7664939151-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="7664939151-5">&lt;&lt;</span><span class="p" data-group-id="7664939151-6">(</span><span class="p" data-group-id="7664939151-7">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7664939151-7">&gt;&gt;</span><span class="p" data-group-id="7664939151-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="7664939151-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7664939151-8">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7664939151-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="p" data-group-id="7664939151-9">&lt;&lt;</span><span class="p" data-group-id="7664939151-10">(</span><span class="p" data-group-id="7664939151-11">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7664939151-11">&gt;&gt;</span><span class="p" data-group-id="7664939151-10">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7664939151-9">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7664939151-12">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7664939151-12">&gt;&gt;</span></code></pre><p>The first two examples have a unit value of 1 for the segment, while the third
│ │ │ +the unit value for the segment; otherwise an exception is raised.</p><p>For example, the following examples all succeed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3362013504-1">&lt;&lt;</span><span class="p" data-group-id="3362013504-2">(</span><span class="p" data-group-id="3362013504-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3362013504-3">&gt;&gt;</span><span class="p" data-group-id="3362013504-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3362013504-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3362013504-4">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3362013504-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="3362013504-5">&lt;&lt;</span><span class="p" data-group-id="3362013504-6">(</span><span class="p" data-group-id="3362013504-7">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3362013504-7">&gt;&gt;</span><span class="p" data-group-id="3362013504-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3362013504-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3362013504-8">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3362013504-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +3&gt; </span><span class="p" data-group-id="3362013504-9">&lt;&lt;</span><span class="p" data-group-id="3362013504-10">(</span><span class="p" data-group-id="3362013504-11">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3362013504-11">&gt;&gt;</span><span class="p" data-group-id="3362013504-10">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3362013504-9">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3362013504-12">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3362013504-12">&gt;&gt;</span></code></pre><p>The first two examples have a unit value of 1 for the segment, while the third
│ │ │  segment has a unit value of 8.</p><p>Attempting to interpolate a bit string of size 1 into a binary segment with unit
│ │ │ -8 (the default unit for <code class="inline">binary</code>) fails as shown in this example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5637952419-1">&lt;&lt;</span><span class="p" data-group-id="5637952419-2">(</span><span class="p" data-group-id="5637952419-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="5637952419-3">&gt;&gt;</span><span class="p" data-group-id="5637952419-2">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5637952419-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="gt">** exception error: bad argument</span></code></pre><p>For the construction to succeed, the unit value of the segment must be 1:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="2520317953-1">&lt;&lt;</span><span class="p" data-group-id="2520317953-2">(</span><span class="p" data-group-id="2520317953-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2520317953-3">&gt;&gt;</span><span class="p" data-group-id="2520317953-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="2520317953-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2520317953-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2520317953-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="p" data-group-id="2520317953-5">&lt;&lt;</span><span class="p" data-group-id="2520317953-6">(</span><span class="p" data-group-id="2520317953-7">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2520317953-7">&gt;&gt;</span><span class="p" data-group-id="2520317953-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2520317953-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2520317953-8">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2520317953-8">&gt;&gt;</span></code></pre><p>Similarly, when matching a binary segment with no size specified, the match
│ │ │ +8 (the default unit for <code class="inline">binary</code>) fails as shown in this example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9296457036-1">&lt;&lt;</span><span class="p" data-group-id="9296457036-2">(</span><span class="p" data-group-id="9296457036-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="9296457036-3">&gt;&gt;</span><span class="p" data-group-id="9296457036-2">)</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="9296457036-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="gt">** exception error: bad argument</span></code></pre><p>For the construction to succeed, the unit value of the segment must be 1:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="8150910630-1">&lt;&lt;</span><span class="p" data-group-id="8150910630-2">(</span><span class="p" data-group-id="8150910630-3">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="8150910630-3">&gt;&gt;</span><span class="p" data-group-id="8150910630-2">)</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="8150910630-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8150910630-4">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="8150910630-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +3&gt; </span><span class="p" data-group-id="8150910630-5">&lt;&lt;</span><span class="p" data-group-id="8150910630-6">(</span><span class="p" data-group-id="8150910630-7">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="8150910630-7">&gt;&gt;</span><span class="p" data-group-id="8150910630-6">)</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="8150910630-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8150910630-8">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="8150910630-8">&gt;&gt;</span></code></pre><p>Similarly, when matching a binary segment with no size specified, the match
│ │ │  succeeds if and only if the size in bits of the rest of the binary is evenly
│ │ │ -divisible by the unit value:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="2169138336-1">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="2169138336-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2169138336-2">&lt;&lt;</span><span class="s">&quot;&quot;</span><span class="p" data-group-id="2169138336-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2169138336-3">&lt;&lt;</span><span class="p" data-group-id="2169138336-3">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="2169138336-4">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="2169138336-4">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2169138336-5">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="2169138336-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +divisible by the unit value:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="1003653428-1">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="1003653428-1">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1003653428-2">&lt;&lt;</span><span class="s">&quot;&quot;</span><span class="p" data-group-id="1003653428-2">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1003653428-3">&lt;&lt;</span><span class="p" data-group-id="1003653428-3">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="1003653428-4">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="1003653428-4">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1003653428-5">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="1003653428-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no match of right hand side value &lt;&lt;&quot;a&quot;&gt;&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="p" data-group-id="2169138336-6">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="2169138336-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2169138336-7">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="2169138336-7">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2169138336-8">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="2169138336-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="p" data-group-id="2169138336-9">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="2169138336-9">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2169138336-10">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="2169138336-10">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="p" data-group-id="1003653428-6">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="1003653428-6">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1003653428-7">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="1003653428-7">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1003653428-8">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="1003653428-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +4&gt; </span><span class="p" data-group-id="1003653428-9">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="1003653428-9">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1003653428-10">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="1003653428-10">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no match of right hand side value &lt;&lt;&quot;abc&quot;&gt;&gt;</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="p" data-group-id="2169138336-11">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="2169138336-11">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2169138336-12">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="2169138336-12">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2169138336-13">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="2169138336-13">&gt;&gt;</span></code></pre><p>When a size is explicitly specified for a binary segment, the segment size in
│ │ │ +5&gt; </span><span class="p" data-group-id="1003653428-11">&lt;&lt;</span><span class="p">_</span><span class="o">/</span><span class="ss">binary</span><span class="o">-</span><span class="nc">unit</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="1003653428-11">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1003653428-12">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="1003653428-12">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1003653428-13">&lt;&lt;</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="1003653428-13">&gt;&gt;</span></code></pre><p>When a size is explicitly specified for a binary segment, the segment size in
│ │ │  bits is the value of <code class="inline">Size</code> multiplied by the default or explicit unit value.</p><p>When constructing binaries, the size of the binary being interpolated into the
│ │ │ -constructed binary must be at least as large as the size of the binary segment.</p><p><strong>Examples:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7288694888-1">&lt;&lt;</span><span class="p" data-group-id="7288694888-2">(</span><span class="p" data-group-id="7288694888-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="7288694888-3">&gt;&gt;</span><span class="p" data-group-id="7288694888-2">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7288694888-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7288694888-4">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="7288694888-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="7288694888-5">&lt;&lt;</span><span class="p" data-group-id="7288694888-6">(</span><span class="p" data-group-id="7288694888-7">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="7288694888-7">&gt;&gt;</span><span class="p" data-group-id="7288694888-6">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="7288694888-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +constructed binary must be at least as large as the size of the binary segment.</p><p><strong>Examples:</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="6867662416-1">&lt;&lt;</span><span class="p" data-group-id="6867662416-2">(</span><span class="p" data-group-id="6867662416-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="6867662416-3">&gt;&gt;</span><span class="p" data-group-id="6867662416-2">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6867662416-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6867662416-4">&lt;&lt;</span><span class="s">&quot;ab&quot;</span><span class="p" data-group-id="6867662416-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="6867662416-5">&lt;&lt;</span><span class="p" data-group-id="6867662416-6">(</span><span class="p" data-group-id="6867662416-7">&lt;&lt;</span><span class="s">&quot;a&quot;</span><span class="p" data-group-id="6867662416-7">&gt;&gt;</span><span class="p" data-group-id="6867662416-6">)</span><span class="p">:</span><span class="mi">2</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="6867662416-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: construction of binary failed
│ │ │          *** segment 1 of type &#39;binary&#39;: the value &lt;&lt;&quot;a&quot;&gt;&gt; is shorter than the size of the segment</span></code></pre><h3 id="unicode-segments" class="section-heading">
│ │ │    <a href="#unicode-segments" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Unicode segments</span>
│ │ │  </h3>
│ │ │ @@ -900,78 +900,78 @@
│ │ │  range <code class="inline">0</code> through <code class="inline">16#D7FF</code> or <code class="inline">16#E000</code> through <code class="inline">16#10FFFF</code>. The match fails if the
│ │ │  returned value falls outside those ranges.</p><p>A segment of type <code class="inline">utf8</code> matches 1-4 bytes in the bit string, if the bit string
│ │ │  at the match position contains a valid UTF-8 sequence. (See RFC-3629 or the
│ │ │  Unicode standard.)</p><p>A segment of type <code class="inline">utf16</code> can match 2 or 4 bytes in the bit string. The match
│ │ │  fails if the bit string at the match position does not contain a legal UTF-16
│ │ │  encoding of a Unicode code point. (See RFC-2781 or the Unicode standard.)</p><p>A segment of type <code class="inline">utf32</code> can match 4 bytes in the bit string in the same way as
│ │ │  an <code class="inline">integer</code> segment matches 32 bits. The match fails if the resulting integer
│ │ │ -is outside the legal ranges previously mentioned.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="3851938535-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="3851938535-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="3851938535-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-4">&lt;&lt;</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="3851938535-4">&gt;&gt;</span><span class="w">
│ │ │ +is outside the legal ranges previously mentioned.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5143163882-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5143163882-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-3">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="5143163882-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-4">&lt;&lt;</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="5143163882-4">&gt;&gt;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="3851938535-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-6">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="3851938535-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="p" data-group-id="3851938535-7">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="3851938535-7">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-8">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="3851938535-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-9">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="3851938535-9">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +</span><span class="mi">3</span><span class="o">&gt;</span><span class="w"> </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="5143163882-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-6">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5143163882-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +4&gt; </span><span class="p" data-group-id="5143163882-7">&lt;&lt;</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="5143163882-7">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-8">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="5143163882-8">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-9">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5143163882-9">&gt;&gt;</span><span class="gp unselectable">
│ │ │  5&gt; </span><span class="n">C</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="p" data-group-id="3851938535-10">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="n">E</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="3851938535-10">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-11">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="3851938535-11">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-12">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="3851938535-12">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +6&gt; </span><span class="p" data-group-id="5143163882-10">&lt;&lt;</span><span class="n">D</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="n">E</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="5143163882-10">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-11">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="5143163882-11">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-12">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5143163882-12">&gt;&gt;</span><span class="gp unselectable">
│ │ │  7&gt; </span><span class="n">D</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">273</span><span class="gp unselectable">
│ │ │  8&gt; </span><span class="n">F</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │ -9&gt; </span><span class="p" data-group-id="3851938535-13">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">H</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="3851938535-13">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-14">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="3851938535-14">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-15">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="3851938535-15">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +9&gt; </span><span class="p" data-group-id="5143163882-13">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">H</span><span class="o">/</span><span class="ss">binary</span><span class="p" data-group-id="5143163882-13">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-14">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="5143163882-14">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-15">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5143163882-15">&gt;&gt;</span><span class="gp unselectable">
│ │ │  10&gt; </span><span class="n">H</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-16">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="3851938535-16">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -11&gt; </span><span class="p" data-group-id="3851938535-17">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">J</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="3851938535-17">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-18">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="3851938535-18">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-19">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="3851938535-19">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +</span><span class="p" data-group-id="5143163882-16">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">42</span><span class="p" data-group-id="5143163882-16">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +11&gt; </span><span class="p" data-group-id="5143163882-17">&lt;&lt;</span><span class="n">G</span><span class="p">,</span><span class="n">J</span><span class="o">/</span><span class="ss">bitstring</span><span class="p" data-group-id="5143163882-17">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-18">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">42</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="5143163882-18">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-19">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="5143163882-19">&gt;&gt;</span><span class="gp unselectable">
│ │ │  12&gt; </span><span class="n">J</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-20">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="3851938535-20">&gt;&gt;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-20">&lt;&lt;</span><span class="mi">17</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">10</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="5143163882-20">&gt;&gt;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="mi">13</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="3851938535-21">&lt;&lt;</span><span class="mi">1024</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="3851938535-21">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-22">&lt;&lt;</span><span class="mi">208</span><span class="p">,</span><span class="mi">128</span><span class="p" data-group-id="3851938535-22">&gt;&gt;</span><span class="w">
│ │ │ +</span><span class="mi">13</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="5143163882-21">&lt;&lt;</span><span class="mi">1024</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="5143163882-21">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-22">&lt;&lt;</span><span class="mi">208</span><span class="p">,</span><span class="mi">128</span><span class="p" data-group-id="5143163882-22">&gt;&gt;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="mi">14</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="3851938535-23">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">:</span><span class="mi">7</span><span class="p" data-group-id="3851938535-23">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-24">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="3851938535-24">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -15&gt; </span><span class="p" data-group-id="3851938535-25">&lt;&lt;</span><span class="mi">16#123</span><span class="p">:</span><span class="mi">12</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="3851938535-25">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-26">&lt;&lt;</span><span class="mi">16#231</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="3851938535-26">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3851938535-27">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="3851938535-27">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3851938535-28">&lt;&lt;</span><span class="mi">35</span><span class="p">,</span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="3851938535-28">&gt;&gt;</span></code></pre><p>Notice that bit string patterns cannot be nested.</p><p>Notice also that &quot;<code class="inline">B=&lt;&lt;1&gt;&gt;</code>&quot; is interpreted as &quot;<code class="inline">B =&lt; &lt;1&gt;&gt;</code>&quot; which is a syntax
│ │ │ +</span><span class="mi">14</span><span class="o">&gt;</span><span class="w"> </span><span class="p" data-group-id="5143163882-23">&lt;&lt;</span><span class="mi">1</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">:</span><span class="mi">7</span><span class="p" data-group-id="5143163882-23">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-24">&lt;&lt;</span><span class="mi">128</span><span class="p" data-group-id="5143163882-24">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +15&gt; </span><span class="p" data-group-id="5143163882-25">&lt;&lt;</span><span class="mi">16#123</span><span class="p">:</span><span class="mi">12</span><span class="o">/</span><span class="ss">little</span><span class="p" data-group-id="5143163882-25">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-26">&lt;&lt;</span><span class="mi">16#231</span><span class="p">:</span><span class="mi">12</span><span class="p" data-group-id="5143163882-26">&gt;&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5143163882-27">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">:</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="5143163882-27">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5143163882-28">&lt;&lt;</span><span class="mi">35</span><span class="p">,</span><span class="mi">1</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="5143163882-28">&gt;&gt;</span></code></pre><p>Notice that bit string patterns cannot be nested.</p><p>Notice also that &quot;<code class="inline">B=&lt;&lt;1&gt;&gt;</code>&quot; is interpreted as &quot;<code class="inline">B =&lt; &lt;1&gt;&gt;</code>&quot; which is a syntax
│ │ │  error. The correct way is to write a space after <code class="inline">=</code>: &quot;<code class="inline">B = &lt;&lt;1&gt;&gt;</code>.</p><p>More examples are provided in <a href="../../doc/system/bit_syntax.html">Programming Examples</a>.</p><h2 id="fun-expressions" class="section-heading">
│ │ │    <a href="#fun-expressions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Fun Expressions</span>
│ │ │  </h2>
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">fun</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5869779598-1">[</span><span class="n">Name</span><span class="p" data-group-id="5869779598-1">]</span><span class="p" data-group-id="5869779598-2">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="5869779598-2">)</span><span class="w"> </span><span class="p" data-group-id="5869779598-3">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="5869779598-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2692291612-1">[</span><span class="n">Name</span><span class="p" data-group-id="2692291612-1">]</span><span class="p" data-group-id="2692291612-2">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="2692291612-2">)</span><span class="w"> </span><span class="p" data-group-id="2692291612-3">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="2692291612-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5869779598-4">[</span><span class="n">Name</span><span class="p" data-group-id="5869779598-4">]</span><span class="p" data-group-id="5869779598-5">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="5869779598-5">)</span><span class="w"> </span><span class="p" data-group-id="5869779598-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="5869779598-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2692291612-4">[</span><span class="n">Name</span><span class="p" data-group-id="2692291612-4">]</span><span class="p" data-group-id="2692291612-5">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="2692291612-5">)</span><span class="w"> </span><span class="p" data-group-id="2692291612-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="2692291612-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                </span><span class="n">BodyK</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>A fun expression begins with the keyword <code class="inline">fun</code> and ends with the keyword <code class="inline">end</code>.
│ │ │  Between them is to be a function declaration, similar to a
│ │ │  <a href="ref_man_functions.html#function-declaration-syntax">regular function declaration</a>,
│ │ │  except that the function name is optional and is to be a variable, if any.</p><p>Variables in a fun head shadow the function name and both shadow variables in
│ │ │  the function clause surrounding the fun expression. Variables bound in a fun
│ │ │ -body are local to the fun body.</p><p>The return value of the expression is the resulting fun.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="8653659490-1">(</span><span class="n">X</span><span class="p" data-group-id="8653659490-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +body are local to the fun body.</p><p>The return value of the expression is the resulting fun.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Fun1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="9777173545-1">(</span><span class="n">X</span><span class="p" data-group-id="9777173545-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">+</span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="8653659490-2">(</span><span class="mi">2</span><span class="p" data-group-id="8653659490-2">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="n">Fun1</span><span class="p" data-group-id="9777173545-2">(</span><span class="mi">2</span><span class="p" data-group-id="9777173545-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="n">Fun2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="8653659490-3">(</span><span class="n">X</span><span class="p" data-group-id="8653659490-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="o">&gt;=</span><span class="mi">5</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">gt</span><span class="p">;</span><span class="w"> </span><span class="p" data-group-id="8653659490-4">(</span><span class="n">X</span><span class="p" data-group-id="8653659490-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">lt</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="n">Fun2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="9777173545-3">(</span><span class="n">X</span><span class="p" data-group-id="9777173545-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="o">&gt;=</span><span class="mi">5</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">gt</span><span class="p">;</span><span class="w"> </span><span class="p" data-group-id="9777173545-4">(</span><span class="n">X</span><span class="p" data-group-id="9777173545-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">lt</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="n">Fun2</span><span class="p" data-group-id="8653659490-5">(</span><span class="mi">7</span><span class="p" data-group-id="8653659490-5">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="n">Fun2</span><span class="p" data-group-id="9777173545-5">(</span><span class="mi">7</span><span class="p" data-group-id="9777173545-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">gt</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="n">Fun3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="8653659490-6">(</span><span class="mi">1</span><span class="p" data-group-id="8653659490-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="8653659490-7">(</span><span class="n">X</span><span class="p" data-group-id="8653659490-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="8653659490-8">(</span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="8653659490-8">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="n">Fun3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="9777173545-6">(</span><span class="mi">1</span><span class="p" data-group-id="9777173545-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="9777173545-7">(</span><span class="n">X</span><span class="p" data-group-id="9777173545-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">Fact</span><span class="p" data-group-id="9777173545-8">(</span><span class="n">X</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="9777173545-8">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.39074546</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="n">Fun3</span><span class="p" data-group-id="8653659490-9">(</span><span class="mi">4</span><span class="p" data-group-id="8653659490-9">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="n">Fun3</span><span class="p" data-group-id="9777173545-9">(</span><span class="mi">4</span><span class="p" data-group-id="9777173545-9">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">24</span></code></pre><p>The following fun expressions are also allowed:</p><pre><code class="makeup erlang" translate="no"><span class="k">fun</span><span class="w"> </span><span class="n">Name</span><span class="o">/</span><span class="n">Arity</span><span class="w">
│ │ │  </span><span class="k">fun</span><span class="w"> </span><span class="n">Module</span><span class="p">:</span><span class="n">Name</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>In <code class="inline">Name/Arity</code>, <code class="inline">Name</code> is an atom and <code class="inline">Arity</code> is an integer. <code class="inline">Name/Arity</code> must
│ │ │ -specify an existing local function. The expression is syntactic sugar for:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="1186581754-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="1186581754-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="1186581754-2">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="1186581754-2">)</span><span class="w"> </span><span class="k">end</span></code></pre><p>In <code class="inline">Module:Name/Arity</code>, <code class="inline">Module</code>, and <code class="inline">Name</code> are atoms and <code class="inline">Arity</code> is an
│ │ │ +specify an existing local function. The expression is syntactic sugar for:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3596264109-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="3596264109-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3596264109-2">(</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="3596264109-2">)</span><span class="w"> </span><span class="k">end</span></code></pre><p>In <code class="inline">Module:Name/Arity</code>, <code class="inline">Module</code>, and <code class="inline">Name</code> are atoms and <code class="inline">Arity</code> is an
│ │ │  integer. <code class="inline">Module</code>, <code class="inline">Name</code>, and <code class="inline">Arity</code> can also be variables. A fun defined in
│ │ │  this way refers to the function <code class="inline">Name</code> with arity <code class="inline">Arity</code> in the <em>latest</em>
│ │ │  version of module <code class="inline">Module</code>. A fun defined in this way is not dependent on the
│ │ │  code for the module in which it is defined.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP R15, <code class="inline">Module</code>, <code class="inline">Name</code>, and <code class="inline">Arity</code> were not allowed to be
│ │ │  variables.</p></section><p>More examples are provided in <a href="../../doc/system/funs.html">Programming Examples</a>.</p><h2 id="catch-and-throw" class="section-heading">
│ │ │    <a href="#catch-and-throw" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -981,35 +981,35 @@
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">catch</span><span class="w"> </span><span class="n">Expr</span></code></pre><p>Returns the value of <code class="inline">Expr</code> unless an exception is raised during the evaluation. In
│ │ │  that case, the exception is caught. The return value depends on the class of the
│ │ │  exception:</p><ul><li><p><strong><code class="inline">error</code></strong> (a run-time error or the code called <a href="../../erts-15.2.7.3/doc/html/erlang.html#error/1"><code class="inline">error(Term)</code></a>) -
│ │ │  <code class="inline">{'EXIT',{Reason,Stack}}</code> is returned.</p></li><li><p><strong><code class="inline">exit</code></strong> (the code called <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit(Term)</code></a>) - <code class="inline">{'EXIT',Term}</code> is returned.</p></li><li><p><strong><code class="inline">throw</code></strong> (the code called <a href="../../erts-15.2.7.3/doc/html/erlang.html#throw/1"><code class="inline">throw(Term)</code></a>): <code class="inline">Term</code> is returned.</p></li></ul><p><code class="inline">Reason</code> depends on the type of error that occurred, and <code class="inline">Stack</code> is the stack of
│ │ │  recent function calls, see <a href="errors.html#exit_reasons">Exit Reasons</a>.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="k">catch</span><span class="w"> </span><span class="mi">1</span><span class="o">+</span><span class="mi">2</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │  2&gt; </span><span class="k">catch</span><span class="w"> </span><span class="mi">1</span><span class="o">+</span><span class="ss">a</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0928483688-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="0928483688-2">{</span><span class="ss">badarith</span><span class="p">,</span><span class="p" data-group-id="0928483688-3">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0928483688-3">]</span><span class="p" data-group-id="0928483688-2">}</span><span class="p" data-group-id="0928483688-1">}</span></code></pre><p>The BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#throw/1"><code class="inline">throw(Any)</code></a> can be used for non-local return from a
│ │ │ -function. It must be evaluated within a <code class="inline">catch</code>, which returns the value <code class="inline">Any</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="7817356553-1">(</span><span class="ss">hello</span><span class="p" data-group-id="7817356553-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5269608499-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="5269608499-2">{</span><span class="ss">badarith</span><span class="p">,</span><span class="p" data-group-id="5269608499-3">[</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5269608499-3">]</span><span class="p" data-group-id="5269608499-2">}</span><span class="p" data-group-id="5269608499-1">}</span></code></pre><p>The BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#throw/1"><code class="inline">throw(Any)</code></a> can be used for non-local return from a
│ │ │ +function. It must be evaluated within a <code class="inline">catch</code>, which returns the value <code class="inline">Any</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="3179365004-1">(</span><span class="ss">hello</span><span class="p" data-group-id="3179365004-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span></code></pre><p>If <a href="../../erts-15.2.7.3/doc/html/erlang.html#throw/1"><code class="inline">throw/1</code></a> is not evaluated within a catch, a <code class="inline">nocatch</code> run-time
│ │ │  error occurs.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 24, the <code class="inline">catch</code> operator had the lowest precedence, making
│ │ │ -it necessary to add parentheses when combining it with the <code class="inline">match</code> operator:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7205365761-1">(</span><span class="k">catch</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="7205365761-1">)</span><span class="p">.</span><span class="w">
│ │ │ +it necessary to add parentheses when combining it with the <code class="inline">match</code> operator:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4285661355-1">(</span><span class="k">catch</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="4285661355-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │  2&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span></code></pre><p>Starting from Erlang/OTP 24, the parentheses can be omitted:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">A</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">catch</span><span class="w"> </span><span class="mi">42</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span><span class="gp unselectable">
│ │ │  2&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">42</span></code></pre></section><h2 id="try" class="section-heading">
│ │ │    <a href="#try" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Try</span>
│ │ │  </h2>
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w">
│ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ -    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="0838105454-1">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="0838105454-1">]</span><span class="w"> </span><span class="p" data-group-id="0838105454-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="0838105454-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="7922192425-1">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="7922192425-1">]</span><span class="w"> </span><span class="p" data-group-id="7922192425-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="7922192425-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="0838105454-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="0838105454-3">]</span><span class="w"> </span><span class="p" data-group-id="0838105454-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="0838105454-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="7922192425-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="7922192425-3">]</span><span class="w"> </span><span class="p" data-group-id="7922192425-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="7922192425-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>This is an enhancement of <a href="expressions.html#catch-and-throw">catch</a>. It gives the
│ │ │  possibility to:</p><ul><li>Distinguish between different exception classes.</li><li>Choose to handle only the desired ones.</li><li>Passing the others on to an enclosing <code class="inline">try</code> or <code class="inline">catch</code>, or to default error
│ │ │  handling.</li></ul><p>Notice that although the keyword <code class="inline">catch</code> is used in the <code class="inline">try</code> expression, there
│ │ │  is not a <code class="inline">catch</code> expression within the <code class="inline">try</code> expression.</p><p>It returns the value of <code class="inline">Exprs</code> (a sequence of expressions <code class="inline">Expr1, ..., ExprN</code>)
│ │ │  unless an exception occurs during the evaluation. In that case the exception is
│ │ │  caught and the patterns <code class="inline">ExceptionPattern</code> with the right exception class
│ │ │ @@ -1019,47 +1019,47 @@
│ │ │  stack trace is bound to the variable when the corresponding <code class="inline">ExceptionPattern</code>
│ │ │  matches.</p><p>If an exception occurs during evaluation of <code class="inline">Exprs</code> but there is no matching
│ │ │  <code class="inline">ExceptionPattern</code> of the right <code class="inline">Class</code> with a true guard sequence, the
│ │ │  exception is passed on as if <code class="inline">Exprs</code> had not been enclosed in a <code class="inline">try</code>
│ │ │  expression.</p><p>If an exception occurs during evaluation of <code class="inline">ExceptionBody</code>, it is not caught.</p><p>It is allowed to omit <code class="inline">Class</code> and <code class="inline">Stacktrace</code>. An omitted <code class="inline">Class</code> is shorthand
│ │ │  for <code class="inline">throw</code>:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w">
│ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ -    </span><span class="n">ExceptionPattern1</span><span class="w"> </span><span class="p" data-group-id="3980299472-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="3980299472-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">ExceptionPattern1</span><span class="w"> </span><span class="p" data-group-id="1763769291-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="1763769291-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">ExceptionPatternN</span><span class="w"> </span><span class="p" data-group-id="3980299472-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="3980299472-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">ExceptionPatternN</span><span class="w"> </span><span class="p" data-group-id="1763769291-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="1763769291-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>The <code class="inline">try</code> expression can have an <code class="inline">of</code> section:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="0687793621-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="0687793621-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="5890509082-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="5890509082-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="0687793621-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="0687793621-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="5890509082-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="5890509082-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ -    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="0687793621-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="0687793621-3">]</span><span class="w"> </span><span class="p" data-group-id="0687793621-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="0687793621-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="5890509082-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="5890509082-3">]</span><span class="w"> </span><span class="p" data-group-id="5890509082-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="5890509082-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="0687793621-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="0687793621-5">]</span><span class="w"> </span><span class="p" data-group-id="0687793621-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="0687793621-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="5890509082-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="5890509082-5">]</span><span class="w"> </span><span class="p" data-group-id="5890509082-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="5890509082-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>If the evaluation of <code class="inline">Exprs</code> succeeds without an exception, the patterns
│ │ │  <code class="inline">Pattern</code> are sequentially matched against the result in the same way as for a
│ │ │  <a href="expressions.html#case">case</a> expression, except that if the matching fails, a
│ │ │  <code class="inline">try_clause</code> run-time error occurs instead of a <code class="inline">case_clause</code>.</p><p>Only exceptions occurring during the evaluation of <code class="inline">Exprs</code> can be caught by the
│ │ │  <code class="inline">catch</code> section. Exceptions occurring in a <code class="inline">Body</code> or due to a failed match are
│ │ │  not caught.</p><p>The <code class="inline">try</code> expression can also be augmented with an <code class="inline">after</code> section, intended to
│ │ │  be used for cleanup with side effects:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="3251099205-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="3251099205-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pattern1</span><span class="w"> </span><span class="p" data-group-id="9090062653-1">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="9090062653-1">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="3251099205-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="3251099205-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PatternN</span><span class="w"> </span><span class="p" data-group-id="9090062653-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqN</span><span class="p" data-group-id="9090062653-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">BodyN</span><span class="w">
│ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ -    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="3251099205-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="3251099205-3">]</span><span class="w"> </span><span class="p" data-group-id="3251099205-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="3251099205-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Class1</span><span class="p">:</span><span class="n">ExceptionPattern1</span><span class="p" data-group-id="9090062653-3">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="9090062653-3">]</span><span class="w"> </span><span class="p" data-group-id="9090062653-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeq1</span><span class="p" data-group-id="9090062653-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBody1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="3251099205-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="3251099205-5">]</span><span class="w"> </span><span class="p" data-group-id="3251099205-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="3251099205-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">ClassN</span><span class="p">:</span><span class="n">ExceptionPatternN</span><span class="p" data-group-id="9090062653-5">[</span><span class="p">:</span><span class="n">Stacktrace</span><span class="p" data-group-id="9090062653-5">]</span><span class="w"> </span><span class="p" data-group-id="9090062653-6">[</span><span class="k">when</span><span class="w"> </span><span class="n">ExceptionGuardSeqN</span><span class="p" data-group-id="9090062653-6">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="n">ExceptionBodyN</span><span class="w">
│ │ │  </span><span class="k">after</span><span class="w">
│ │ │      </span><span class="n">AfterBody</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p><code class="inline">AfterBody</code> is evaluated after either <code class="inline">Body</code> or <code class="inline">ExceptionBody</code>, no matter which
│ │ │  one. The evaluated value of <code class="inline">AfterBody</code> is lost; the return value of the <code class="inline">try</code>
│ │ │  expression is the same with an <code class="inline">after</code> section as without.</p><p>Even if an exception occurs during evaluation of <code class="inline">Body</code> or <code class="inline">ExceptionBody</code>,
│ │ │  <code class="inline">AfterBody</code> is evaluated. In this case the exception is passed on after
│ │ │ @@ -1082,40 +1082,40 @@
│ │ │          </span><span class="n">ExpressionBody</span><span class="w">
│ │ │  </span><span class="k">after</span><span class="w">
│ │ │      </span><span class="n">AfterBody</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="w">
│ │ │  
│ │ │  </span><span class="k">try</span><span class="w"> </span><span class="n">Exprs</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="n">AfterBody</span><span class="w"> </span><span class="k">end</span></code></pre><p>Next is an example of using <code class="inline">after</code>. This closes the file, even in the event of
│ │ │  exceptions in <a href="../../lib/kernel-10.2.7.2/doc/html/file.html#read/2"><code class="inline">file:read/2</code></a> or in <a href="../../erts-15.2.7.3/doc/html/erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>. The
│ │ │ -exceptions are the same as without the <code class="inline">try</code>...<code class="inline">after</code>...<code class="inline">end</code> expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">termize_file</span><span class="p" data-group-id="0402016405-1">(</span><span class="n">Name</span><span class="p" data-group-id="0402016405-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0402016405-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="0402016405-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="0402016405-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0402016405-4">[</span><span class="ss">read</span><span class="p">,</span><span class="ss">binary</span><span class="p" data-group-id="0402016405-4">]</span><span class="p" data-group-id="0402016405-3">)</span><span class="p">,</span><span class="w">
│ │ │ +exceptions are the same as without the <code class="inline">try</code>...<code class="inline">after</code>...<code class="inline">end</code> expression:</p><pre><code class="makeup erlang" translate="no"><span class="nf">termize_file</span><span class="p" data-group-id="3435735099-1">(</span><span class="n">Name</span><span class="p" data-group-id="3435735099-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3435735099-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">F</span><span class="p" data-group-id="3435735099-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="3435735099-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3435735099-4">[</span><span class="ss">read</span><span class="p">,</span><span class="ss">binary</span><span class="p" data-group-id="3435735099-4">]</span><span class="p" data-group-id="3435735099-3">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">try</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0402016405-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">Bin</span><span class="p" data-group-id="0402016405-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="0402016405-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1024</span><span class="o">*</span><span class="mi">1024</span><span class="p" data-group-id="0402016405-6">)</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="nf">binary_to_term</span><span class="p" data-group-id="0402016405-7">(</span><span class="n">Bin</span><span class="p" data-group-id="0402016405-7">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="3435735099-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="n">Bin</span><span class="p" data-group-id="3435735099-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="3435735099-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="mi">1024</span><span class="o">*</span><span class="mi">1024</span><span class="p" data-group-id="3435735099-6">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="nf">binary_to_term</span><span class="p" data-group-id="3435735099-7">(</span><span class="n">Bin</span><span class="p" data-group-id="3435735099-7">)</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w">
│ │ │ -        </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="0402016405-8">(</span><span class="n">F</span><span class="p" data-group-id="0402016405-8">)</span><span class="w">
│ │ │ +        </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="3435735099-8">(</span><span class="n">F</span><span class="p" data-group-id="3435735099-8">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Next is an example of using <code class="inline">try</code> to emulate <code class="inline">catch Expr</code>:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w"> </span><span class="n">Expr</span><span class="w">
│ │ │  </span><span class="k">catch</span><span class="w">
│ │ │      </span><span class="nc">throw</span><span class="p">:</span><span class="n">Term</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Term</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nc">exit</span><span class="p">:</span><span class="n">Reason</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2432497124-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="2432497124-1">}</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nc">error</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stk</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2432497124-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="2432497124-3">{</span><span class="n">Reason</span><span class="p">,</span><span class="n">Stk</span><span class="p" data-group-id="2432497124-3">}</span><span class="p" data-group-id="2432497124-2">}</span><span class="w">
│ │ │ +    </span><span class="nc">exit</span><span class="p">:</span><span class="n">Reason</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3008728735-1">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="n">Reason</span><span class="p" data-group-id="3008728735-1">}</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nc">error</span><span class="p">:</span><span class="n">Reason</span><span class="p">:</span><span class="n">Stk</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3008728735-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="3008728735-3">{</span><span class="n">Reason</span><span class="p">,</span><span class="n">Stk</span><span class="p" data-group-id="3008728735-3">}</span><span class="p" data-group-id="3008728735-2">}</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>Variables bound in the various parts of these expressions have different scopes.
│ │ │  Variables bound just after the <code class="inline">try</code> keyword are:</p><ul><li>bound in the <code class="inline">of</code> section</li><li>unsafe in both the <code class="inline">catch</code> and <code class="inline">after</code> sections, as well as after the whole
│ │ │  construct</li></ul><p>Variables bound in <code class="inline">of</code> section are:</p><ul><li>unbound in the <code class="inline">catch</code> section</li><li>unsafe in both the <code class="inline">after</code> section, as well as after the whole construct</li></ul><p>Variables bound in the <code class="inline">catch</code> section are unsafe in the <code class="inline">after</code> section, as
│ │ │  well as after the whole construct.</p><p>Variables bound in the <code class="inline">after</code> section are unsafe after the whole construct.</p><h2 id="parenthesized-expressions" class="section-heading">
│ │ │    <a href="#parenthesized-expressions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Parenthesized Expressions</span>
│ │ │  </h2>
│ │ │ -<pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4426971050-1">(</span><span class="n">Expr</span><span class="p" data-group-id="4426971050-1">)</span></code></pre><p>Parenthesized expressions are useful to override
│ │ │ +<pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0625847145-1">(</span><span class="n">Expr</span><span class="p" data-group-id="0625847145-1">)</span></code></pre><p>Parenthesized expressions are useful to override
│ │ │  <a href="expressions.html#prec">operator precedences</a>, for example, in arithmetic
│ │ │  expressions:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">7</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="2945025397-1">(</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2945025397-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="p" data-group-id="6026195103-1">(</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6026195103-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">9</span></code></pre><h2 id="block-expressions" class="section-heading">
│ │ │    <a href="#block-expressions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Block Expressions</span>
│ │ │  </h2>
│ │ │  <pre><code class="makeup erlang" translate="no"><span class="k">begin</span><span class="w">
│ │ │ @@ -1127,71 +1127,71 @@
│ │ │    <a href="#comprehensions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Comprehensions</span>
│ │ │  </h2>
│ │ │  <p>Comprehensions provide a succinct notation for iterating over one or more terms
│ │ │  and constructing a new term. Comprehensions come in three different flavors,
│ │ │ -depending on the type of term they build.</p><p>List comprehensions construct lists. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5700695967-1">[</span><span class="n">Expr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="5700695967-1">]</span></code></pre><p>Here, <code class="inline">Expr</code> is an arbitrary expression, and each <code class="inline">Qualifier</code> is either a
│ │ │ +depending on the type of term they build.</p><p>List comprehensions construct lists. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8342346473-1">[</span><span class="n">Expr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="8342346473-1">]</span></code></pre><p>Here, <code class="inline">Expr</code> is an arbitrary expression, and each <code class="inline">Qualifier</code> is either a
│ │ │  <strong>generator</strong> or a <strong>filter</strong>.</p><p>Bit string comprehensions construct bit strings or binaries. They have the
│ │ │ -following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7009865571-1">&lt;&lt;</span><span class="w"> </span><span class="n">BitStringExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="w"> </span><span class="p" data-group-id="7009865571-1">&gt;&gt;</span></code></pre><p><code class="inline">BitStringExpr</code> is an expression that evaluates to a bit string. If
│ │ │ +following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5951055425-1">&lt;&lt;</span><span class="w"> </span><span class="n">BitStringExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="w"> </span><span class="p" data-group-id="5951055425-1">&gt;&gt;</span></code></pre><p><code class="inline">BitStringExpr</code> is an expression that evaluates to a bit string. If
│ │ │  <code class="inline">BitStringExpr</code> is a function call, it must be enclosed in parentheses. Each
│ │ │ -<code class="inline">Qualifier</code> is either a <strong>generator</strong> or a <strong>filter</strong>.</p><p>Map comprehensions construct maps. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2157744086-1">#{</span><span class="n">KeyExpr</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="2157744086-1">}</span></code></pre><p>Here, <code class="inline">KeyExpr</code> and <code class="inline">ValueExpr</code> are arbitrary expressions, and each <code class="inline">Qualifier</code>
│ │ │ +<code class="inline">Qualifier</code> is either a <strong>generator</strong> or a <strong>filter</strong>.</p><p>Map comprehensions construct maps. They have the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0072994111-1">#{</span><span class="n">KeyExpr</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueExpr</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Qualifier1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">QualifierN</span><span class="p" data-group-id="0072994111-1">}</span></code></pre><p>Here, <code class="inline">KeyExpr</code> and <code class="inline">ValueExpr</code> are arbitrary expressions, and each <code class="inline">Qualifier</code>
│ │ │  is either a <strong>generator</strong> or a <strong>filter</strong>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Map comprehensions and map generators were introduced in Erlang/OTP 26.</p></section><p>There are three kinds of generators.</p><p>A <em>list generator</em> has the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">Pattern</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">ListExpr</span></code></pre><p>where <code class="inline">ListExpr</code> is an expression that evaluates to a list of terms.</p><p>A <em>bit string generator</em> has the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">BitstringPattern</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="n">BitStringExpr</span></code></pre><p>where <code class="inline">BitStringExpr</code> is an expression that evaluates to a bit string.</p><p>A <em>map generator</em> has the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">KeyPattern</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">ValuePattern</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">MapExpression</span></code></pre><p>where <code class="inline">MapExpr</code> is an expression that evaluates to a map, or a map iterator
│ │ │  obtained by calling <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#iterator/1"><code class="inline">maps:iterator/1</code></a> or <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#iterator/2"><code class="inline">maps:iterator/2</code></a>.</p><p>A <em>filter</em> is an expression that evaluates to <code class="inline">true</code> or <code class="inline">false</code>.</p><p>The variables in the generator patterns shadow previously bound variables,
│ │ │  including variables bound in a previous generator pattern.</p><p>Variables bound in a generator expression are not visible outside the
│ │ │ -expression:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5191320595-1">[</span><span class="p" data-group-id="5191320595-2">{</span><span class="n">E</span><span class="p">,</span><span class="n">L</span><span class="p" data-group-id="5191320595-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="o">=</span><span class="p" data-group-id="5191320595-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5191320595-3">]</span><span class="p" data-group-id="5191320595-1">]</span><span class="p">.</span><span class="w">
│ │ │ +expression:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="8879654110-1">[</span><span class="p" data-group-id="8879654110-2">{</span><span class="n">E</span><span class="p">,</span><span class="n">L</span><span class="p" data-group-id="8879654110-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="o">=</span><span class="p" data-group-id="8879654110-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8879654110-3">]</span><span class="p" data-group-id="8879654110-1">]</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">* 1:5: variable &#39;L&#39; is unbound</span></code></pre><p>A <strong>list comprehension</strong> returns a list, where the list elements are the result
│ │ │  of evaluating <code class="inline">Expr</code> for each combination of generator elements for which all
│ │ │  filters are true.</p><p>A <strong>bit string comprehension</strong> returns a bit string, which is created by
│ │ │  concatenating the results of evaluating <code class="inline">BitStringExpr</code> for each combination of
│ │ │  bit string generator elements for which all filters are true.</p><p>A <strong>map comprehension</strong> returns a map, where the map elements are the result of
│ │ │  evaluating <code class="inline">KeyExpr</code> and <code class="inline">ValueExpr</code> for each combination of generator elements
│ │ │  for which all filters are true. If the key expressions are not unique, the last
│ │ │ -occurrence is stored in the map.</p><p><strong>Examples:</strong></p><p>Multiplying each element in a list by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3790846447-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="3790846447-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3790846447-2">]</span><span class="p" data-group-id="3790846447-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3790846447-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3790846447-3">]</span></code></pre><p>Multiplying each byte in a binary by two, returning a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9659463397-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="9659463397-2">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="9659463397-2">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="9659463397-3">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9659463397-3">&gt;&gt;</span><span class="p" data-group-id="9659463397-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9659463397-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="9659463397-4">]</span></code></pre><p>Multiplying each byte in a binary by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="2085407931-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="2085407931-2">&lt;&lt;</span><span class="p" data-group-id="2085407931-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="2085407931-3">)</span><span class="p" data-group-id="2085407931-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="2085407931-4">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="2085407931-4">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="2085407931-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2085407931-5">&gt;&gt;</span><span class="w"> </span><span class="p" data-group-id="2085407931-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2085407931-6">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2085407931-6">&gt;&gt;</span></code></pre><p>Multiplying each element in a list by two, returning a binary:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0533378059-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="0533378059-2">&lt;&lt;</span><span class="p" data-group-id="0533378059-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="0533378059-3">)</span><span class="p" data-group-id="0533378059-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="0533378059-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0533378059-4">]</span><span class="w"> </span><span class="p" data-group-id="0533378059-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0533378059-5">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="0533378059-5">&gt;&gt;</span></code></pre><p>Creating a mapping from an integer to its square:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="8685683612-1">#{</span><span class="n">X</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="8685683612-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8685683612-2">]</span><span class="p" data-group-id="8685683612-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8685683612-3">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="8685683612-3">}</span></code></pre><p>Multiplying the value of each element in a map by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="6222784878-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">V</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="6222784878-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="6222784878-2">}</span><span class="p" data-group-id="6222784878-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6222784878-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="6222784878-3">}</span></code></pre><p>Filtering a list, keeping odd numbers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3571651537-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="3571651537-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3571651537-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3571651537-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3571651537-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3571651537-3">]</span></code></pre><p>Filtering a list, keeping only elements that match:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="8708501027-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="8708501027-2">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8708501027-2">}</span><span class="o">=</span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="8708501027-3">[</span><span class="p" data-group-id="8708501027-4">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8708501027-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8708501027-5">[</span><span class="ss">a</span><span class="p" data-group-id="8708501027-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8708501027-6">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="8708501027-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8708501027-7">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8708501027-7">}</span><span class="p" data-group-id="8708501027-3">]</span><span class="p" data-group-id="8708501027-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8708501027-8">[</span><span class="p" data-group-id="8708501027-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8708501027-9">}</span><span class="p">,</span><span class="p" data-group-id="8708501027-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8708501027-10">}</span><span class="p" data-group-id="8708501027-8">]</span></code></pre><p>Combining elements from two list generators:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="2495982299-1">[</span><span class="p" data-group-id="2495982299-2">{</span><span class="n">P</span><span class="p">,</span><span class="n">Q</span><span class="p" data-group-id="2495982299-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="2495982299-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="2495982299-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Q</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="2495982299-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2495982299-4">]</span><span class="p" data-group-id="2495982299-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2495982299-5">[</span><span class="p" data-group-id="2495982299-6">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2495982299-6">}</span><span class="p">,</span><span class="p" data-group-id="2495982299-7">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2495982299-7">}</span><span class="p">,</span><span class="p" data-group-id="2495982299-8">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2495982299-8">}</span><span class="p">,</span><span class="p" data-group-id="2495982299-9">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2495982299-9">}</span><span class="p">,</span><span class="p" data-group-id="2495982299-10">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2495982299-10">}</span><span class="p">,</span><span class="p" data-group-id="2495982299-11">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2495982299-11">}</span><span class="p" data-group-id="2495982299-5">]</span></code></pre><p>More examples are provided in
│ │ │ +occurrence is stored in the map.</p><p><strong>Examples:</strong></p><p>Multiplying each element in a list by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4719983081-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="4719983081-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4719983081-2">]</span><span class="p" data-group-id="4719983081-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4719983081-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="4719983081-3">]</span></code></pre><p>Multiplying each byte in a binary by two, returning a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="0900188637-1">[</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="0900188637-2">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="0900188637-2">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="0900188637-3">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0900188637-3">&gt;&gt;</span><span class="p" data-group-id="0900188637-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0900188637-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="0900188637-4">]</span></code></pre><p>Multiplying each byte in a binary by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="3741458555-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="3741458555-2">&lt;&lt;</span><span class="p" data-group-id="3741458555-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="3741458555-3">)</span><span class="p" data-group-id="3741458555-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="3741458555-4">&lt;&lt;</span><span class="n">X</span><span class="p" data-group-id="3741458555-4">&gt;&gt;</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="p" data-group-id="3741458555-5">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3741458555-5">&gt;&gt;</span><span class="w"> </span><span class="p" data-group-id="3741458555-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3741458555-6">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3741458555-6">&gt;&gt;</span></code></pre><p>Multiplying each element in a list by two, returning a binary:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9822874315-1">&lt;&lt;</span><span class="w"> </span><span class="p" data-group-id="9822874315-2">&lt;&lt;</span><span class="p" data-group-id="9822874315-3">(</span><span class="n">X</span><span class="o">*</span><span class="mi">2</span><span class="p" data-group-id="9822874315-3">)</span><span class="p" data-group-id="9822874315-2">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9822874315-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9822874315-4">]</span><span class="w"> </span><span class="p" data-group-id="9822874315-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9822874315-5">&lt;&lt;</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="9822874315-5">&gt;&gt;</span></code></pre><p>Creating a mapping from an integer to its square:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4921513271-1">#{</span><span class="n">X</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="4921513271-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4921513271-2">]</span><span class="p" data-group-id="4921513271-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4921513271-3">#{</span><span class="mi">1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="4921513271-3">}</span></code></pre><p>Multiplying the value of each element in a map by two:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4598534847-1">#{</span><span class="n">K</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">V</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">K</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="4598534847-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="4598534847-2">}</span><span class="p" data-group-id="4598534847-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4598534847-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="4598534847-3">}</span></code></pre><p>Filtering a list, keeping odd numbers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9504268120-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9504268120-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9504268120-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="9504268120-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9504268120-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9504268120-3">]</span></code></pre><p>Filtering a list, keeping only elements that match:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="5068796654-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="5068796654-2">{</span><span class="p">_</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5068796654-2">}</span><span class="o">=</span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5068796654-3">[</span><span class="p" data-group-id="5068796654-4">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5068796654-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5068796654-5">[</span><span class="ss">a</span><span class="p" data-group-id="5068796654-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5068796654-6">{</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="5068796654-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5068796654-7">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5068796654-7">}</span><span class="p" data-group-id="5068796654-3">]</span><span class="p" data-group-id="5068796654-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5068796654-8">[</span><span class="p" data-group-id="5068796654-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5068796654-9">}</span><span class="p">,</span><span class="p" data-group-id="5068796654-10">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5068796654-10">}</span><span class="p" data-group-id="5068796654-8">]</span></code></pre><p>Combining elements from two list generators:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7094674025-1">[</span><span class="p" data-group-id="7094674025-2">{</span><span class="n">P</span><span class="p">,</span><span class="n">Q</span><span class="p" data-group-id="7094674025-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">P</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="7094674025-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="7094674025-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Q</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="7094674025-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7094674025-4">]</span><span class="p" data-group-id="7094674025-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7094674025-5">[</span><span class="p" data-group-id="7094674025-6">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="7094674025-6">}</span><span class="p">,</span><span class="p" data-group-id="7094674025-7">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7094674025-7">}</span><span class="p">,</span><span class="p" data-group-id="7094674025-8">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="7094674025-8">}</span><span class="p">,</span><span class="p" data-group-id="7094674025-9">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7094674025-9">}</span><span class="p">,</span><span class="p" data-group-id="7094674025-10">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="7094674025-10">}</span><span class="p">,</span><span class="p" data-group-id="7094674025-11">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7094674025-11">}</span><span class="p" data-group-id="7094674025-5">]</span></code></pre><p>More examples are provided in
│ │ │  <a href="../../doc/system/list_comprehensions.html">Programming Examples.</a></p><p>When there are no generators, a comprehension returns either a term constructed
│ │ │  from a single element (the result of evaluating <code class="inline">Expr</code>) if all filters are true,
│ │ │  or a term constructed from no elements (that is, <code class="inline">[]</code> for list comprehension,
│ │ │ -<code class="inline">&lt;&lt;&gt;&gt;</code> for a bit string comprehension, and <code class="inline">#{}</code> for a map comprehension).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="9663396268-1">[</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="9663396268-2">(</span><span class="mi">2</span><span class="p" data-group-id="9663396268-2">)</span><span class="p" data-group-id="9663396268-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9663396268-3">[</span><span class="mi">2</span><span class="p" data-group-id="9663396268-3">]</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="9663396268-4">[</span><span class="ss">x</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="9663396268-5">(</span><span class="ss">x</span><span class="p" data-group-id="9663396268-5">)</span><span class="p" data-group-id="9663396268-4">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9663396268-6">[</span><span class="p" data-group-id="9663396268-6">]</span></code></pre><p>What happens when the filter expression does not evaluate to a boolean value
│ │ │ +<code class="inline">&lt;&lt;&gt;&gt;</code> for a bit string comprehension, and <code class="inline">#{}</code> for a map comprehension).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4887160699-1">[</span><span class="mi">2</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="4887160699-2">(</span><span class="mi">2</span><span class="p" data-group-id="4887160699-2">)</span><span class="p" data-group-id="4887160699-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4887160699-3">[</span><span class="mi">2</span><span class="p" data-group-id="4887160699-3">]</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="4887160699-4">[</span><span class="ss">x</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="4887160699-5">(</span><span class="ss">x</span><span class="p" data-group-id="4887160699-5">)</span><span class="p" data-group-id="4887160699-4">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4887160699-6">[</span><span class="p" data-group-id="4887160699-6">]</span></code></pre><p>What happens when the filter expression does not evaluate to a boolean value
│ │ │  depends on the expression:</p><ul><li>If the expression is a <a href="expressions.html#guard-expressions">guard expression</a>,
│ │ │  failure to evaluate or evaluating to a non-boolean value is equivalent to
│ │ │  evaluating to <code class="inline">false</code>.</li><li>If the expression is not a guard expression and evaluates to a non-Boolean
│ │ │  value <code class="inline">Val</code>, an exception <code class="inline">{bad_filter, Val}</code> is triggered at runtime. If the
│ │ │  evaluation of the expression raises an exception, it is not caught by the
│ │ │ -comprehension.</li></ul><p><strong>Examples</strong> (using a guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3086293015-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3086293015-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3086293015-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3086293015-2">]</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="3086293015-3">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3086293015-3">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3086293015-4">[</span><span class="p" data-group-id="3086293015-4">]</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="p" data-group-id="3086293015-5">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3086293015-5">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3086293015-6">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3086293015-6">]</span></code></pre><p><strong>Examples</strong> (using a non-guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2632567581-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2632567581-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2632567581-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2632567581-2">]</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="n">FaultyIsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="2632567581-3">(</span><span class="n">E</span><span class="p" data-group-id="2632567581-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +comprehension.</li></ul><p><strong>Examples</strong> (using a guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0056693292-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0056693292-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0056693292-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0056693292-2">]</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="0056693292-3">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="0056693292-3">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0056693292-4">[</span><span class="p" data-group-id="0056693292-4">]</span><span class="gp unselectable">
│ │ │ +3&gt; </span><span class="p" data-group-id="0056693292-5">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="0056693292-5">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0056693292-6">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0056693292-6">]</span></code></pre><p><strong>Examples</strong> (using a non-guard expression as filter):</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7751587817-1">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7751587817-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7751587817-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7751587817-2">]</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="n">FaultyIsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="7751587817-3">(</span><span class="n">E</span><span class="p" data-group-id="7751587817-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">42.17316486</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="p" data-group-id="2632567581-4">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">FaultyIsEven</span><span class="p" data-group-id="2632567581-5">(</span><span class="n">E</span><span class="p" data-group-id="2632567581-5">)</span><span class="p" data-group-id="2632567581-4">]</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="p" data-group-id="7751587817-4">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">FaultyIsEven</span><span class="p" data-group-id="7751587817-5">(</span><span class="n">E</span><span class="p" data-group-id="7751587817-5">)</span><span class="p" data-group-id="7751587817-4">]</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: bad filter 1</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="n">IsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="2632567581-6">(</span><span class="n">E</span><span class="p" data-group-id="2632567581-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="n">IsEven</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="7751587817-6">(</span><span class="n">E</span><span class="p" data-group-id="7751587817-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">42.17316486</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="p" data-group-id="2632567581-7">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="2632567581-8">(</span><span class="n">E</span><span class="p" data-group-id="2632567581-8">)</span><span class="p" data-group-id="2632567581-7">]</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="p" data-group-id="7751587817-7">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="7751587817-8">(</span><span class="n">E</span><span class="p" data-group-id="7751587817-8">)</span><span class="p" data-group-id="7751587817-7">]</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: an error occurred when evaluating an arithmetic expression
│ │ │       in operator  rem/2
│ │ │          called as a rem 2</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="p" data-group-id="2632567581-9">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="2632567581-10">(</span><span class="n">E</span><span class="p" data-group-id="2632567581-10">)</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="2632567581-11">(</span><span class="n">E</span><span class="p" data-group-id="2632567581-11">)</span><span class="p" data-group-id="2632567581-9">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2632567581-12">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2632567581-12">]</span></code></pre><p><a href="" id="guards"></a></p><h2 id="guard-sequences" class="section-heading">
│ │ │ +6&gt; </span><span class="p" data-group-id="7751587817-9">[</span><span class="n">E</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="7751587817-10">(</span><span class="n">E</span><span class="p" data-group-id="7751587817-10">)</span><span class="p">,</span><span class="w"> </span><span class="n">IsEven</span><span class="p" data-group-id="7751587817-11">(</span><span class="n">E</span><span class="p" data-group-id="7751587817-11">)</span><span class="p" data-group-id="7751587817-9">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7751587817-12">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7751587817-12">]</span></code></pre><p><a href="" id="guards"></a></p><h2 id="guard-sequences" class="section-heading">
│ │ │    <a href="#guard-sequences" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Guard Sequences</span>
│ │ │  </h2>
│ │ │  <p>A <em>guard sequence</em> is a sequence of guards, separated by semicolon (<code class="inline">;</code>). The
│ │ │  guard sequence is true if at least one of the guards is true. (The remaining
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/funs.html
│ │ │ @@ -117,402 +117,402 @@
│ │ │  
│ │ │  <h2 id="map" class="section-heading">
│ │ │    <a href="#map" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">map</span>
│ │ │  </h2>
│ │ │ -<p>The following function, <code class="inline">double</code>, doubles every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="6843161962-1">(</span><span class="p" data-group-id="6843161962-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6843161962-2">]</span><span class="p" data-group-id="6843161962-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6843161962-3">[</span><span class="mi">2</span><span class="o">*</span><span class="n">H</span><span class="p">|</span><span class="nf">double</span><span class="p" data-group-id="6843161962-4">(</span><span class="n">T</span><span class="p" data-group-id="6843161962-4">)</span><span class="p" data-group-id="6843161962-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">double</span><span class="p" data-group-id="6843161962-5">(</span><span class="p" data-group-id="6843161962-6">[</span><span class="p" data-group-id="6843161962-6">]</span><span class="p" data-group-id="6843161962-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6843161962-7">[</span><span class="p" data-group-id="6843161962-7">]</span><span class="p">.</span></code></pre><p>Hence, the argument entered as input is doubled as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">double</span><span class="p" data-group-id="8729866177-1">(</span><span class="p" data-group-id="8729866177-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="8729866177-2">]</span><span class="p" data-group-id="8729866177-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8729866177-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p" data-group-id="8729866177-3">]</span></code></pre><p>The following function, <code class="inline">add_one</code>, adds one to every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add_one</span><span class="p" data-group-id="0136067599-1">(</span><span class="p" data-group-id="0136067599-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0136067599-2">]</span><span class="p" data-group-id="0136067599-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0136067599-3">[</span><span class="n">H</span><span class="o">+</span><span class="mi">1</span><span class="p">|</span><span class="nf">add_one</span><span class="p" data-group-id="0136067599-4">(</span><span class="n">T</span><span class="p" data-group-id="0136067599-4">)</span><span class="p" data-group-id="0136067599-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">add_one</span><span class="p" data-group-id="0136067599-5">(</span><span class="p" data-group-id="0136067599-6">[</span><span class="p" data-group-id="0136067599-6">]</span><span class="p" data-group-id="0136067599-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0136067599-7">[</span><span class="p" data-group-id="0136067599-7">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> have a similar structure. This can be used
│ │ │ -by writing a function <code class="inline">map</code> that expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="0535923983-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0535923983-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0535923983-2">]</span><span class="p" data-group-id="0535923983-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0535923983-3">[</span><span class="n">F</span><span class="p" data-group-id="0535923983-4">(</span><span class="n">H</span><span class="p" data-group-id="0535923983-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="0535923983-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="0535923983-5">)</span><span class="p" data-group-id="0535923983-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="0535923983-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0535923983-7">[</span><span class="p" data-group-id="0535923983-7">]</span><span class="p" data-group-id="0535923983-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0535923983-8">[</span><span class="p" data-group-id="0535923983-8">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> can now be expressed in terms of <code class="inline">map</code> as
│ │ │ -follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="1372027461-1">(</span><span class="n">L</span><span class="p" data-group-id="1372027461-1">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="1372027461-2">(</span><span class="nf">fun</span><span class="p" data-group-id="1372027461-3">(</span><span class="n">X</span><span class="p" data-group-id="1372027461-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="1372027461-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add_one</span><span class="p" data-group-id="1372027461-4">(</span><span class="n">L</span><span class="p" data-group-id="1372027461-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="1372027461-5">(</span><span class="nf">fun</span><span class="p" data-group-id="1372027461-6">(</span><span class="n">X</span><span class="p" data-group-id="1372027461-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="1372027461-5">)</span><span class="p">.</span></code></pre><p><code class="inline">map(F, List)</code> is a function that takes a function <code class="inline">F</code> and a list <code class="inline">L</code> as
│ │ │ +<p>The following function, <code class="inline">double</code>, doubles every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="3118084767-1">(</span><span class="p" data-group-id="3118084767-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3118084767-2">]</span><span class="p" data-group-id="3118084767-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3118084767-3">[</span><span class="mi">2</span><span class="o">*</span><span class="n">H</span><span class="p">|</span><span class="nf">double</span><span class="p" data-group-id="3118084767-4">(</span><span class="n">T</span><span class="p" data-group-id="3118084767-4">)</span><span class="p" data-group-id="3118084767-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">double</span><span class="p" data-group-id="3118084767-5">(</span><span class="p" data-group-id="3118084767-6">[</span><span class="p" data-group-id="3118084767-6">]</span><span class="p" data-group-id="3118084767-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3118084767-7">[</span><span class="p" data-group-id="3118084767-7">]</span><span class="p">.</span></code></pre><p>Hence, the argument entered as input is doubled as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">double</span><span class="p" data-group-id="4037713519-1">(</span><span class="p" data-group-id="4037713519-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="4037713519-2">]</span><span class="p" data-group-id="4037713519-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4037713519-3">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p" data-group-id="4037713519-3">]</span></code></pre><p>The following function, <code class="inline">add_one</code>, adds one to every element in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">add_one</span><span class="p" data-group-id="8378088623-1">(</span><span class="p" data-group-id="8378088623-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8378088623-2">]</span><span class="p" data-group-id="8378088623-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8378088623-3">[</span><span class="n">H</span><span class="o">+</span><span class="mi">1</span><span class="p">|</span><span class="nf">add_one</span><span class="p" data-group-id="8378088623-4">(</span><span class="n">T</span><span class="p" data-group-id="8378088623-4">)</span><span class="p" data-group-id="8378088623-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">add_one</span><span class="p" data-group-id="8378088623-5">(</span><span class="p" data-group-id="8378088623-6">[</span><span class="p" data-group-id="8378088623-6">]</span><span class="p" data-group-id="8378088623-5">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8378088623-7">[</span><span class="p" data-group-id="8378088623-7">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> have a similar structure. This can be used
│ │ │ +by writing a function <code class="inline">map</code> that expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="1446850279-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1446850279-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1446850279-2">]</span><span class="p" data-group-id="1446850279-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1446850279-3">[</span><span class="n">F</span><span class="p" data-group-id="1446850279-4">(</span><span class="n">H</span><span class="p" data-group-id="1446850279-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="1446850279-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="1446850279-5">)</span><span class="p" data-group-id="1446850279-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="1446850279-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1446850279-7">[</span><span class="p" data-group-id="1446850279-7">]</span><span class="p" data-group-id="1446850279-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1446850279-8">[</span><span class="p" data-group-id="1446850279-8">]</span><span class="p">.</span></code></pre><p>The functions <code class="inline">double</code> and <code class="inline">add_one</code> can now be expressed in terms of <code class="inline">map</code> as
│ │ │ +follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">double</span><span class="p" data-group-id="6112968553-1">(</span><span class="n">L</span><span class="p" data-group-id="6112968553-1">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="6112968553-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6112968553-3">(</span><span class="n">X</span><span class="p" data-group-id="6112968553-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="o">*</span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6112968553-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add_one</span><span class="p" data-group-id="6112968553-4">(</span><span class="n">L</span><span class="p" data-group-id="6112968553-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="6112968553-5">(</span><span class="nf">fun</span><span class="p" data-group-id="6112968553-6">(</span><span class="n">X</span><span class="p" data-group-id="6112968553-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6112968553-5">)</span><span class="p">.</span></code></pre><p><code class="inline">map(F, List)</code> is a function that takes a function <code class="inline">F</code> and a list <code class="inline">L</code> as
│ │ │  arguments and returns a new list, obtained by applying <code class="inline">F</code> to each of the
│ │ │  elements in <code class="inline">L</code>.</p><p>The process of abstracting out the common features of a number of different
│ │ │  programs is called <em>procedural abstraction</em>. Procedural abstraction can be used
│ │ │  to write several different functions that have a similar structure, but differ
│ │ │  in some minor detail. This is done as follows:</p><ol><li><em>Step 1.</em> Write one function that represents the common features of these
│ │ │  functions.</li><li><em>Step 2.</em> Parameterize the difference in terms of functions that are passed
│ │ │  as arguments to the common function.</li></ol><h2 id="foreach" class="section-heading">
│ │ │    <a href="#foreach" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">foreach</span>
│ │ │  </h2>
│ │ │  <p>This section illustrates procedural abstraction. Initially, the following two
│ │ │ -examples are written as conventional functions.</p><p>This function prints all elements of a list onto a stream:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="9053353915-1">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9053353915-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9053353915-2">]</span><span class="p" data-group-id="9053353915-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9053353915-3">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9053353915-4">[</span><span class="n">H</span><span class="p" data-group-id="9053353915-4">]</span><span class="p" data-group-id="9053353915-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">print_list</span><span class="p" data-group-id="9053353915-5">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9053353915-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">print_list</span><span class="p" data-group-id="9053353915-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9053353915-7">[</span><span class="p" data-group-id="9053353915-7">]</span><span class="p" data-group-id="9053353915-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>This function broadcasts a message to a list of processes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">broadcast</span><span class="p" data-group-id="3159184473-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3159184473-2">[</span><span class="n">Pid</span><span class="p">|</span><span class="n">Pids</span><span class="p" data-group-id="3159184473-2">]</span><span class="p" data-group-id="3159184473-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +examples are written as conventional functions.</p><p>This function prints all elements of a list onto a stream:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="5207737200-1">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5207737200-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5207737200-2">]</span><span class="p" data-group-id="5207737200-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5207737200-3">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5207737200-4">[</span><span class="n">H</span><span class="p" data-group-id="5207737200-4">]</span><span class="p" data-group-id="5207737200-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">print_list</span><span class="p" data-group-id="5207737200-5">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="5207737200-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">print_list</span><span class="p" data-group-id="5207737200-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5207737200-7">[</span><span class="p" data-group-id="5207737200-7">]</span><span class="p" data-group-id="5207737200-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>This function broadcasts a message to a list of processes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">broadcast</span><span class="p" data-group-id="7763443405-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7763443405-2">[</span><span class="n">Pid</span><span class="p">|</span><span class="n">Pids</span><span class="p" data-group-id="7763443405-2">]</span><span class="p" data-group-id="7763443405-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">Msg</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">broadcast</span><span class="p" data-group-id="3159184473-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">Pids</span><span class="p" data-group-id="3159184473-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">broadcast</span><span class="p" data-group-id="3159184473-4">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3159184473-5">[</span><span class="p" data-group-id="3159184473-5">]</span><span class="p" data-group-id="3159184473-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">broadcast</span><span class="p" data-group-id="7763443405-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">Pids</span><span class="p" data-group-id="7763443405-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">broadcast</span><span class="p" data-group-id="7763443405-4">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7763443405-5">[</span><span class="p" data-group-id="7763443405-5">]</span><span class="p" data-group-id="7763443405-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">true</span><span class="p">.</span></code></pre><p>These two functions have a similar structure. They both iterate over a list and
│ │ │  do something to each element in the list. The &quot;something&quot; is passed on as an
│ │ │ -extra argument to the function that does this.</p><p>The function <code class="inline">foreach</code> expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="5851611037-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5851611037-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5851611037-2">]</span><span class="p" data-group-id="5851611037-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">F</span><span class="p" data-group-id="5851611037-3">(</span><span class="n">H</span><span class="p" data-group-id="5851611037-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="5851611037-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="5851611037-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">foreach</span><span class="p" data-group-id="5851611037-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5851611037-6">[</span><span class="p" data-group-id="5851611037-6">]</span><span class="p" data-group-id="5851611037-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">print_list</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="4349922672-1">(</span><span class="nf">fun</span><span class="p" data-group-id="4349922672-2">(</span><span class="n">H</span><span class="p" data-group-id="4349922672-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4349922672-3">(</span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="4349922672-4">[</span><span class="n">H</span><span class="p" data-group-id="4349922672-4">]</span><span class="p" data-group-id="4349922672-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4349922672-1">)</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">broadcast</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="1521969182-1">(</span><span class="nf">fun</span><span class="p" data-group-id="1521969182-2">(</span><span class="n">Pid</span><span class="p" data-group-id="1521969182-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="1521969182-1">)</span></code></pre><p><code class="inline">foreach</code> is evaluated for its side-effect and not its value. <code class="inline">foreach(Fun ,L)</code>
│ │ │ +extra argument to the function that does this.</p><p>The function <code class="inline">foreach</code> expresses this similarity:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="9689587319-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9689587319-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9689587319-2">]</span><span class="p" data-group-id="9689587319-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">F</span><span class="p" data-group-id="9689587319-3">(</span><span class="n">H</span><span class="p" data-group-id="9689587319-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="9689587319-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9689587319-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">foreach</span><span class="p" data-group-id="9689587319-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9689587319-6">[</span><span class="p" data-group-id="9689587319-6">]</span><span class="p" data-group-id="9689587319-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">print_list</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="4581065553-1">(</span><span class="nf">fun</span><span class="p" data-group-id="4581065553-2">(</span><span class="n">H</span><span class="p" data-group-id="4581065553-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4581065553-3">(</span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="4581065553-4">[</span><span class="n">H</span><span class="p" data-group-id="4581065553-4">]</span><span class="p" data-group-id="4581065553-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4581065553-1">)</span></code></pre><p>Using the function <code class="inline">foreach</code>, the function <code class="inline">broadcast</code> becomes:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="3574672084-1">(</span><span class="nf">fun</span><span class="p" data-group-id="3574672084-2">(</span><span class="n">Pid</span><span class="p" data-group-id="3574672084-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="3574672084-1">)</span></code></pre><p><code class="inline">foreach</code> is evaluated for its side-effect and not its value. <code class="inline">foreach(Fun ,L)</code>
│ │ │  calls <code class="inline">Fun(X)</code> for each element <code class="inline">X</code> in <code class="inline">L</code> and the processing occurs in the
│ │ │  order that the elements were defined in <code class="inline">L</code>. <code class="inline">map</code> does not define the order in
│ │ │  which its elements are processed.</p><h2 id="syntax-of-funs" class="section-heading">
│ │ │    <a href="#syntax-of-funs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Syntax of Funs</span>
│ │ │  </h2>
│ │ │  <p>Funs are written with the following syntax (see
│ │ │ -<a href="../../doc/system/expressions.html#fun-expressions">Fun Expressions </a>for full description):</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2318787849-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">ArgN</span><span class="p" data-group-id="2318787849-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +<a href="../../doc/system/expressions.html#fun-expressions">Fun Expressions </a>for full description):</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3762071267-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="n">ArgN</span><span class="p" data-group-id="3762071267-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="k">end</span></code></pre><p>This creates an anonymous function of <code class="inline">N</code> arguments and binds it to the variable
│ │ │  <code class="inline">F</code>.</p><p>Another function, <code class="inline">FunctionName</code>, written in the same module, can be passed as
│ │ │  an argument, using the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">FunctionName</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>With this form of function reference, the function that is referred to does not
│ │ │  need to be exported from the module.</p><p>It is also possible to refer to a function defined in a different module, with
│ │ │ -the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Module</span><span class="p">:</span><span class="n">FunctionName</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>In this case, the function must be exported from the module in question.</p><p>The following program illustrates the different ways of creating funs:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7505388357-1">(</span><span class="ss">fun_test</span><span class="p" data-group-id="7505388357-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7505388357-2">(</span><span class="p" data-group-id="7505388357-3">[</span><span class="ss">t1</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">t2</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7505388357-3">]</span><span class="p" data-group-id="7505388357-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="7505388357-4">(</span><span class="ss">lists</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7505388357-5">[</span><span class="ss">map</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7505388357-5">]</span><span class="p" data-group-id="7505388357-4">)</span><span class="p">.</span><span class="w">
│ │ │ +the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">Module</span><span class="p">:</span><span class="n">FunctionName</span><span class="o">/</span><span class="n">Arity</span></code></pre><p>In this case, the function must be exported from the module in question.</p><p>The following program illustrates the different ways of creating funs:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0416811059-1">(</span><span class="ss">fun_test</span><span class="p" data-group-id="0416811059-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0416811059-2">(</span><span class="p" data-group-id="0416811059-3">[</span><span class="ss">t1</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">t2</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0416811059-3">]</span><span class="p" data-group-id="0416811059-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">import</span><span class="p" data-group-id="0416811059-4">(</span><span class="ss">lists</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0416811059-5">[</span><span class="ss">map</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0416811059-5">]</span><span class="p" data-group-id="0416811059-4">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">t1</span><span class="p" data-group-id="7505388357-6">(</span><span class="p" data-group-id="7505388357-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="7505388357-7">(</span><span class="nf">fun</span><span class="p" data-group-id="7505388357-8">(</span><span class="n">X</span><span class="p" data-group-id="7505388357-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7505388357-9">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7505388357-9">]</span><span class="p" data-group-id="7505388357-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">t1</span><span class="p" data-group-id="0416811059-6">(</span><span class="p" data-group-id="0416811059-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="0416811059-7">(</span><span class="nf">fun</span><span class="p" data-group-id="0416811059-8">(</span><span class="n">X</span><span class="p" data-group-id="0416811059-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0416811059-9">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="0416811059-9">]</span><span class="p" data-group-id="0416811059-7">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">t2</span><span class="p" data-group-id="7505388357-10">(</span><span class="p" data-group-id="7505388357-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="7505388357-11">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7505388357-12">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7505388357-12">]</span><span class="p" data-group-id="7505388357-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">t2</span><span class="p" data-group-id="0416811059-10">(</span><span class="p" data-group-id="0416811059-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">map</span><span class="p" data-group-id="0416811059-11">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0416811059-12">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="0416811059-12">]</span><span class="p" data-group-id="0416811059-11">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">double</span><span class="p" data-group-id="7505388357-13">(</span><span class="n">X</span><span class="p" data-group-id="7505388357-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="p">.</span></code></pre><p>The fun <code class="inline">F</code> can be evaluated with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="p" data-group-id="0826401574-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Argn</span><span class="p" data-group-id="0826401574-1">)</span></code></pre><p>To check whether a term is a fun, use the test
│ │ │ -<a href="../../erts-15.2.7.3/doc/html/erlang.html#is_function/1"><code class="inline">is_function/1</code></a> in a guard.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="6949732026-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="6949732026-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_function</span><span class="p" data-group-id="6949732026-2">(</span><span class="n">F</span><span class="p" data-group-id="6949732026-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="nf">apply</span><span class="p" data-group-id="6949732026-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="6949732026-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="6949732026-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6949732026-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6949732026-5">(</span><span class="n">N</span><span class="p" data-group-id="6949732026-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">double</span><span class="p" data-group-id="0416811059-13">(</span><span class="n">X</span><span class="p" data-group-id="0416811059-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="p">.</span></code></pre><p>The fun <code class="inline">F</code> can be evaluated with the following syntax:</p><pre><code class="makeup erlang" translate="no"><span class="n">F</span><span class="p" data-group-id="2734282107-1">(</span><span class="n">Arg1</span><span class="p">,</span><span class="w"> </span><span class="n">Arg2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Argn</span><span class="p" data-group-id="2734282107-1">)</span></code></pre><p>To check whether a term is a fun, use the test
│ │ │ +<a href="../../erts-15.2.7.3/doc/html/erlang.html#is_function/1"><code class="inline">is_function/1</code></a> in a guard.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="6176233680-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="6176233680-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_function</span><span class="p" data-group-id="6176233680-2">(</span><span class="n">F</span><span class="p" data-group-id="6176233680-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="nf">apply</span><span class="p" data-group-id="6176233680-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="6176233680-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="6176233680-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6176233680-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6176233680-5">(</span><span class="n">N</span><span class="p" data-group-id="6176233680-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │     </span><span class="n">N</span><span class="p">.</span></code></pre><p>Funs are a distinct type. The BIFs <code class="inline">erlang:fun_info/1,2</code> can be used to retrieve
│ │ │  information about a fun, and the BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#fun_to_list/1"><code class="inline">erlang:fun_to_list/1</code></a> returns a textual
│ │ │  representation of a fun. The <a href="../../erts-15.2.7.3/doc/html/erlang.html#check_process_code/2"><code class="inline">check_process_code/2</code></a>
│ │ │  BIF returns <code class="inline">true</code> if the process contains funs that depend on the old version
│ │ │  of a module.</p><h2 id="variable-bindings-within-a-fun" class="section-heading">
│ │ │    <a href="#variable-bindings-within-a-fun" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Variable Bindings Within a Fun</span>
│ │ │  </h2>
│ │ │  <p>The scope rules for variables that occur in funs are as follows:</p><ul><li>All variables that occur in the head of a fun are assumed to be &quot;fresh&quot;
│ │ │  variables.</li><li>Variables that are defined before the fun, and that occur in function calls or
│ │ │ -guard tests within the fun, have the values they had outside the fun.</li><li>Variables cannot be exported from a fun.</li></ul><p>The following examples illustrate these rules:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="4221733740-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="4221733740-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4221733740-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="4221733740-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="4221733740-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="4221733740-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="4221733740-4">(</span><span class="nf">fun</span><span class="p" data-group-id="4221733740-5">(</span><span class="n">X</span><span class="p" data-group-id="4221733740-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4221733740-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="4221733740-7">[</span><span class="n">X</span><span class="p" data-group-id="4221733740-7">]</span><span class="p" data-group-id="4221733740-6">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="4221733740-4">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="4221733740-8">(</span><span class="n">Stream</span><span class="p" data-group-id="4221733740-8">)</span><span class="p">.</span></code></pre><p>Here, the variable <code class="inline">X</code>, defined in the head of the fun, is a new variable. The
│ │ │ +guard tests within the fun, have the values they had outside the fun.</li><li>Variables cannot be exported from a fun.</li></ul><p>The following examples illustrate these rules:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="9057435802-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="9057435802-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9057435802-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="9057435802-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="9057435802-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="9057435802-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="9057435802-4">(</span><span class="nf">fun</span><span class="p" data-group-id="9057435802-5">(</span><span class="n">X</span><span class="p" data-group-id="9057435802-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9057435802-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9057435802-7">[</span><span class="n">X</span><span class="p" data-group-id="9057435802-7">]</span><span class="p" data-group-id="9057435802-6">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="9057435802-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="9057435802-8">(</span><span class="n">Stream</span><span class="p" data-group-id="9057435802-8">)</span><span class="p">.</span></code></pre><p>Here, the variable <code class="inline">X</code>, defined in the head of the fun, is a new variable. The
│ │ │  variable <code class="inline">Stream</code>, which is used within the fun, gets its value from the
│ │ │  <code class="inline">file:open</code> line.</p><p>As any variable that occurs in the head of a fun is considered a new variable,
│ │ │ -it is equally valid to write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="1062929694-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="1062929694-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1062929694-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="1062929694-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="1062929694-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="1062929694-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="1062929694-4">(</span><span class="nf">fun</span><span class="p" data-group-id="1062929694-5">(</span><span class="n">File</span><span class="p" data-group-id="1062929694-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1062929694-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="1062929694-7">[</span><span class="n">File</span><span class="p" data-group-id="1062929694-7">]</span><span class="p" data-group-id="1062929694-6">)</span><span class="w">
│ │ │ -            </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="1062929694-4">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="1062929694-8">(</span><span class="n">Stream</span><span class="p" data-group-id="1062929694-8">)</span><span class="p">.</span></code></pre><p>Here, <code class="inline">File</code> is used as the new variable instead of <code class="inline">X</code>. This is not so wise
│ │ │ +it is equally valid to write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">print_list</span><span class="p" data-group-id="5851355945-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5851355945-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5851355945-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Stream</span><span class="p" data-group-id="5851355945-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="5851355945-3">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="ss">write</span><span class="p" data-group-id="5851355945-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="5851355945-4">(</span><span class="nf">fun</span><span class="p" data-group-id="5851355945-5">(</span><span class="n">File</span><span class="p" data-group-id="5851355945-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5851355945-6">(</span><span class="n">Stream</span><span class="p">,</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="5851355945-7">[</span><span class="n">File</span><span class="p" data-group-id="5851355945-7">]</span><span class="p" data-group-id="5851355945-6">)</span><span class="w">
│ │ │ +            </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5851355945-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">file</span><span class="p">:</span><span class="nf">close</span><span class="p" data-group-id="5851355945-8">(</span><span class="n">Stream</span><span class="p" data-group-id="5851355945-8">)</span><span class="p">.</span></code></pre><p>Here, <code class="inline">File</code> is used as the new variable instead of <code class="inline">X</code>. This is not so wise
│ │ │  because code in the fun body cannot refer to the variable <code class="inline">File</code>, which is
│ │ │  defined outside of the fun. Compiling this example gives the following
│ │ │  diagnostic:</p><pre><code class="text">./FileName.erl:Line: Warning: variable 'File'
│ │ │        shadowed in 'fun'</code></pre><p>This indicates that the variable <code class="inline">File</code>, which is defined inside the fun,
│ │ │  collides with the variable <code class="inline">File</code>, which is defined outside the fun.</p><p>The rules for importing variables into a fun has the consequence that certain
│ │ │  pattern matching operations must be moved into guard expressions and cannot be
│ │ │  written in the head of the fun. For example, you might write the following code
│ │ │  if you intend the first clause of <code class="inline">F</code> to be evaluated when the value of its
│ │ │ -argument is <code class="inline">Y</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="0766203971-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0766203971-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +argument is <code class="inline">Y</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="1215204857-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1215204857-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="nf">map</span><span class="p" data-group-id="0766203971-2">(</span><span class="nf">fun</span><span class="p" data-group-id="0766203971-3">(</span><span class="n">X</span><span class="p" data-group-id="0766203971-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">map</span><span class="p" data-group-id="1215204857-2">(</span><span class="nf">fun</span><span class="p" data-group-id="1215204857-3">(</span><span class="n">X</span><span class="p" data-group-id="1215204857-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │               </span><span class="p">;</span><span class="w">
│ │ │ -           </span><span class="p" data-group-id="0766203971-4">(</span><span class="p">_</span><span class="p" data-group-id="0766203971-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +           </span><span class="p" data-group-id="1215204857-4">(</span><span class="p">_</span><span class="p" data-group-id="1215204857-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │               </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0766203971-2">)</span><span class="w">
│ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>instead of writing the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="3639824528-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3639824528-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1215204857-2">)</span><span class="w">
│ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>instead of writing the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="6346764597-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6346764597-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="nf">map</span><span class="p" data-group-id="3639824528-2">(</span><span class="nf">fun</span><span class="p" data-group-id="3639824528-3">(</span><span class="n">Y</span><span class="p" data-group-id="3639824528-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">map</span><span class="p" data-group-id="6346764597-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6346764597-3">(</span><span class="n">Y</span><span class="p" data-group-id="6346764597-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │               </span><span class="p">;</span><span class="w">
│ │ │ -           </span><span class="p" data-group-id="3639824528-4">(</span><span class="p">_</span><span class="p" data-group-id="3639824528-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +           </span><span class="p" data-group-id="6346764597-4">(</span><span class="p">_</span><span class="p" data-group-id="6346764597-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │               </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3639824528-2">)</span><span class="w">
│ │ │ +        </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6346764597-2">)</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="funs-and-module-lists" class="section-heading">
│ │ │    <a href="#funs-and-module-lists" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Funs and Module Lists</span>
│ │ │  </h2>
│ │ │  <p>The following examples show a dialogue with the Erlang shell. All the higher
│ │ │  order functions discussed are exported from the module <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html"><code class="inline">lists</code></a>.</p><h3 id="map-1" class="section-heading">
│ │ │    <a href="#map-1" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">map</span>
│ │ │  </h3>
│ │ │ -<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#map/2"><code class="inline">lists:map/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="7177943838-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7177943838-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7177943838-2">]</span><span class="p" data-group-id="7177943838-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7177943838-3">[</span><span class="n">F</span><span class="p" data-group-id="7177943838-4">(</span><span class="n">H</span><span class="p" data-group-id="7177943838-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="7177943838-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7177943838-5">)</span><span class="p" data-group-id="7177943838-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="7177943838-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7177943838-7">[</span><span class="p" data-group-id="7177943838-7">]</span><span class="p" data-group-id="7177943838-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7177943838-8">[</span><span class="p" data-group-id="7177943838-8">]</span><span class="p">.</span></code></pre><p>It returns the list obtained by applying the function to every argument in the
│ │ │ +<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#map/2"><code class="inline">lists:map/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">map</span><span class="p" data-group-id="1824696234-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1824696234-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1824696234-2">]</span><span class="p" data-group-id="1824696234-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1824696234-3">[</span><span class="n">F</span><span class="p" data-group-id="1824696234-4">(</span><span class="n">H</span><span class="p" data-group-id="1824696234-4">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="1824696234-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="1824696234-5">)</span><span class="p" data-group-id="1824696234-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="1824696234-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1824696234-7">[</span><span class="p" data-group-id="1824696234-7">]</span><span class="p" data-group-id="1824696234-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1824696234-8">[</span><span class="p" data-group-id="1824696234-8">]</span><span class="p">.</span></code></pre><p>It returns the list obtained by applying the function to every argument in the
│ │ │  list.</p><p>When a new fun is defined in the shell, the value of the fun is printed as
│ │ │ -<code class="inline">Fun#&lt;erl_eval&gt;</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Double</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="6102581113-1">(</span><span class="n">X</span><span class="p" data-group-id="6102581113-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">Fun#&lt;erl_eval&gt;</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Double</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="2393659246-1">(</span><span class="n">X</span><span class="p" data-group-id="2393659246-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="6102581113-2">(</span><span class="n">Double</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6102581113-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6102581113-3">]</span><span class="p" data-group-id="6102581113-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6102581113-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="6102581113-4">]</span></code></pre><h3 id="any" class="section-heading">
│ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="2393659246-2">(</span><span class="n">Double</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2393659246-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2393659246-3">]</span><span class="p" data-group-id="2393659246-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2393659246-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="2393659246-4">]</span></code></pre><h3 id="any" class="section-heading">
│ │ │    <a href="#any" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">any</span>
│ │ │  </h3>
│ │ │ -<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#any/2"><code class="inline">lists:any/2</code></a> takes a predicate <code class="inline">P</code> of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">any</span><span class="p" data-group-id="7884414507-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7884414507-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7884414507-2">]</span><span class="p" data-group-id="7884414507-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="7884414507-3">(</span><span class="n">H</span><span class="p" data-group-id="7884414507-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#any/2"><code class="inline">lists:any/2</code></a> takes a predicate <code class="inline">P</code> of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">any</span><span class="p" data-group-id="5726894786-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5726894786-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5726894786-2">]</span><span class="p" data-group-id="5726894786-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="5726894786-3">(</span><span class="n">H</span><span class="p" data-group-id="5726894786-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">  </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">any</span><span class="p" data-group-id="7884414507-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="7884414507-4">)</span><span class="w">
│ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">any</span><span class="p" data-group-id="5726894786-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="5726894786-4">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">any</span><span class="p" data-group-id="7884414507-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7884414507-6">[</span><span class="p" data-group-id="7884414507-6">]</span><span class="p" data-group-id="7884414507-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">any</span><span class="p" data-group-id="5726894786-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5726894786-6">[</span><span class="p" data-group-id="5726894786-6">]</span><span class="p" data-group-id="5726894786-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">false</span><span class="p">.</span></code></pre><p>A predicate is a function that returns <code class="inline">true</code> or <code class="inline">false</code>. <code class="inline">any</code> is <code class="inline">true</code> if
│ │ │  there is a term <code class="inline">X</code> in the list such that <code class="inline">P(X)</code> is <code class="inline">true</code>.</p><p>A predicate <code class="inline">Big(X)</code> is defined, which is <code class="inline">true</code> if its argument is greater that
│ │ │ -10:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Big</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="3008583208-1">(</span><span class="n">X</span><span class="p" data-group-id="3008583208-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">10</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="p">;</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +10:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Big</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="2222588756-1">(</span><span class="n">X</span><span class="p" data-group-id="2222588756-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">10</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="p">;</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="3008583208-2">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3008583208-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="3008583208-3">]</span><span class="p" data-group-id="3008583208-2">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="2222588756-2">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2222588756-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2222588756-3">]</span><span class="p" data-group-id="2222588756-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="3008583208-4">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3008583208-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3008583208-5">]</span><span class="p" data-group-id="3008583208-4">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">any</span><span class="p" data-group-id="2222588756-4">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2222588756-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2222588756-5">]</span><span class="p" data-group-id="2222588756-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><h3 id="all" class="section-heading">
│ │ │    <a href="#all" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">all</span>
│ │ │  </h3>
│ │ │ -<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#all/2"><code class="inline">lists:all/2</code></a> has the same arguments as <code class="inline">any</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="6471233387-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6471233387-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6471233387-2">]</span><span class="p" data-group-id="6471233387-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="6471233387-3">(</span><span class="n">H</span><span class="p" data-group-id="6471233387-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">all</span><span class="p" data-group-id="6471233387-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="6471233387-4">)</span><span class="p">;</span><span class="w">
│ │ │ +<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#all/2"><code class="inline">lists:all/2</code></a> has the same arguments as <code class="inline">any</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">all</span><span class="p" data-group-id="4346148793-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4346148793-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4346148793-2">]</span><span class="p" data-group-id="4346148793-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="4346148793-3">(</span><span class="n">H</span><span class="p" data-group-id="4346148793-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">  </span><span class="nf">all</span><span class="p" data-group-id="4346148793-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="4346148793-4">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="ss">false</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">all</span><span class="p" data-group-id="6471233387-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6471233387-6">[</span><span class="p" data-group-id="6471233387-6">]</span><span class="p" data-group-id="6471233387-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>It is <code class="inline">true</code> if the predicate applied to all elements in the list is <code class="inline">true</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="2603814099-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2603814099-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2603814099-2">]</span><span class="p" data-group-id="2603814099-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">all</span><span class="p" data-group-id="4346148793-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4346148793-6">[</span><span class="p" data-group-id="4346148793-6">]</span><span class="p" data-group-id="4346148793-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">true</span><span class="p">.</span></code></pre><p>It is <code class="inline">true</code> if the predicate applied to all elements in the list is <code class="inline">true</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="6563149051-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6563149051-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="6563149051-2">]</span><span class="p" data-group-id="6563149051-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="2603814099-3">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2603814099-4">[</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="2603814099-4">]</span><span class="p" data-group-id="2603814099-3">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">all</span><span class="p" data-group-id="6563149051-3">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6563149051-4">[</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="6563149051-4">]</span><span class="p" data-group-id="6563149051-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><h3 id="foreach-1" class="section-heading">
│ │ │    <a href="#foreach-1" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">foreach</span>
│ │ │  </h3>
│ │ │ -<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#foreach/2"><code class="inline">lists:foreach/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="2032938271-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2032938271-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2032938271-2">]</span><span class="p" data-group-id="2032938271-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">F</span><span class="p" data-group-id="2032938271-3">(</span><span class="n">H</span><span class="p" data-group-id="2032938271-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="2032938271-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="2032938271-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">foreach</span><span class="p" data-group-id="2032938271-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2032938271-6">[</span><span class="p" data-group-id="2032938271-6">]</span><span class="p" data-group-id="2032938271-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#foreach/2"><code class="inline">lists:foreach/2</code></a> takes a function of one argument and a list of terms:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="0964142107-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0964142107-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0964142107-2">]</span><span class="p" data-group-id="0964142107-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">F</span><span class="p" data-group-id="0964142107-3">(</span><span class="n">H</span><span class="p" data-group-id="0964142107-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="0964142107-4">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="0964142107-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">foreach</span><span class="p" data-group-id="0964142107-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0964142107-6">[</span><span class="p" data-group-id="0964142107-6">]</span><span class="p" data-group-id="0964142107-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The function is applied to each argument in the list. <code class="inline">foreach</code> returns <code class="inline">ok</code>. It
│ │ │ -is only used for its side-effect:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="9183389038-1">(</span><span class="nf">fun</span><span class="p" data-group-id="9183389038-2">(</span><span class="n">X</span><span class="p" data-group-id="9183389038-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9183389038-3">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9183389038-4">[</span><span class="n">X</span><span class="p" data-group-id="9183389038-4">]</span><span class="p" data-group-id="9183389038-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9183389038-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="9183389038-5">]</span><span class="p" data-group-id="9183389038-1">)</span><span class="p">.</span><span class="w">
│ │ │ +is only used for its side-effect:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="9372691965-1">(</span><span class="nf">fun</span><span class="p" data-group-id="9372691965-2">(</span><span class="n">X</span><span class="p" data-group-id="9372691965-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9372691965-3">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9372691965-4">[</span><span class="n">X</span><span class="p" data-group-id="9372691965-4">]</span><span class="p" data-group-id="9372691965-3">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9372691965-5">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="9372691965-5">]</span><span class="p" data-group-id="9372691965-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">1</span><span class="w">
│ │ │  </span><span class="mi">2</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="w">
│ │ │  </span><span class="mi">4</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><h3 id="foldl" class="section-heading">
│ │ │    <a href="#foldl" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">foldl</span>
│ │ │  </h3>
│ │ │ -<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> takes a function of two arguments, an accumulator and a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foldl</span><span class="p" data-group-id="6777543388-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6777543388-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="6777543388-2">]</span><span class="p" data-group-id="6777543388-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">foldl</span><span class="p" data-group-id="6777543388-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="6777543388-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="6777543388-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="6777543388-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">foldl</span><span class="p" data-group-id="6777543388-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6777543388-6">[</span><span class="p" data-group-id="6777543388-6">]</span><span class="p" data-group-id="6777543388-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Accu</span><span class="p">.</span></code></pre><p>The function is called with two arguments. The first argument is the successive
│ │ │ +<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> takes a function of two arguments, an accumulator and a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foldl</span><span class="p" data-group-id="0776070913-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0776070913-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="0776070913-2">]</span><span class="p" data-group-id="0776070913-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">foldl</span><span class="p" data-group-id="0776070913-3">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="0776070913-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="0776070913-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="0776070913-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">foldl</span><span class="p" data-group-id="0776070913-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0776070913-6">[</span><span class="p" data-group-id="0776070913-6">]</span><span class="p" data-group-id="0776070913-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Accu</span><span class="p">.</span></code></pre><p>The function is called with two arguments. The first argument is the successive
│ │ │  elements in the list. The second argument is the accumulator. The function must
│ │ │  return a new accumulator, which is used the next time the function is called.</p><p>If you have a list of lists <code class="inline">L = [&quot;I&quot;,&quot;like&quot;,&quot;Erlang&quot;]</code>, then you can sum the
│ │ │ -lengths of all the strings in <code class="inline">L</code> as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5756372749-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="5756372749-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5756372749-2">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="5756372749-2">]</span><span class="gp unselectable">
│ │ │ -10&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="5756372749-3">(</span><span class="nf">fun</span><span class="p" data-group-id="5756372749-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="5756372749-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="5756372749-5">(</span><span class="n">X</span><span class="p" data-group-id="5756372749-5">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5756372749-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">11</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> works like a <code class="inline">while</code> loop in an imperative language:</p><pre><code class="makeup erlang" translate="no"><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="p" data-group-id="3878025150-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="3878025150-1">]</span><span class="p">,</span><span class="w">
│ │ │ +lengths of all the strings in <code class="inline">L</code> as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6247375197-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="6247375197-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6247375197-2">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="6247375197-2">]</span><span class="gp unselectable">
│ │ │ +10&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="6247375197-3">(</span><span class="nf">fun</span><span class="p" data-group-id="6247375197-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="6247375197-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="6247375197-5">(</span><span class="n">X</span><span class="p" data-group-id="6247375197-5">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6247375197-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">11</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#foldl/3"><code class="inline">lists:foldl/3</code></a> works like a <code class="inline">while</code> loop in an imperative language:</p><pre><code class="makeup erlang" translate="no"><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="p" data-group-id="4970868330-1">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;like&quot;</span><span class="p">,</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="4970868330-1">]</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="n">Sum</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">while</span><span class="p" data-group-id="3878025150-2">(</span><span class="w"> </span><span class="n">L</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3878025150-3">[</span><span class="p" data-group-id="3878025150-3">]</span><span class="p" data-group-id="3878025150-2">)</span><span class="p" data-group-id="3878025150-4">{</span><span class="w">
│ │ │ -    </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="3878025150-5">(</span><span class="nf">head</span><span class="p" data-group-id="3878025150-6">(</span><span class="n">L</span><span class="p" data-group-id="3878025150-6">)</span><span class="p" data-group-id="3878025150-5">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tail</span><span class="p" data-group-id="3878025150-7">(</span><span class="n">L</span><span class="p" data-group-id="3878025150-7">)</span><span class="w">
│ │ │ +</span><span class="nf">while</span><span class="p" data-group-id="4970868330-2">(</span><span class="w"> </span><span class="n">L</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4970868330-3">[</span><span class="p" data-group-id="4970868330-3">]</span><span class="p" data-group-id="4970868330-2">)</span><span class="p" data-group-id="4970868330-4">{</span><span class="w">
│ │ │ +    </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="4970868330-5">(</span><span class="nf">head</span><span class="p" data-group-id="4970868330-6">(</span><span class="n">L</span><span class="p" data-group-id="4970868330-6">)</span><span class="p" data-group-id="4970868330-5">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">L</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tail</span><span class="p" data-group-id="4970868330-7">(</span><span class="n">L</span><span class="p" data-group-id="4970868330-7">)</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><h3 id="mapfoldl" class="section-heading">
│ │ │    <a href="#mapfoldl" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">mapfoldl</span>
│ │ │  </h3>
│ │ │ -<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#mapfoldl/3"><code class="inline">lists:mapfoldl/3</code></a> simultaneously maps and folds over a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">mapfoldl</span><span class="p" data-group-id="5738270867-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5738270867-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="5738270867-2">]</span><span class="p" data-group-id="5738270867-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5738270867-3">{</span><span class="n">R</span><span class="p">,</span><span class="n">Accu1</span><span class="p" data-group-id="5738270867-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="5738270867-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p" data-group-id="5738270867-4">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5738270867-5">{</span><span class="n">Rs</span><span class="p">,</span><span class="n">Accu2</span><span class="p" data-group-id="5738270867-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">mapfoldl</span><span class="p" data-group-id="5738270867-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu1</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="5738270867-6">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5738270867-7">{</span><span class="p" data-group-id="5738270867-8">[</span><span class="n">R</span><span class="p">|</span><span class="n">Rs</span><span class="p" data-group-id="5738270867-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu2</span><span class="p" data-group-id="5738270867-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">mapfoldl</span><span class="p" data-group-id="5738270867-9">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5738270867-10">[</span><span class="p" data-group-id="5738270867-10">]</span><span class="p" data-group-id="5738270867-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5738270867-11">{</span><span class="p" data-group-id="5738270867-12">[</span><span class="p" data-group-id="5738270867-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="5738270867-11">}</span><span class="p">.</span></code></pre><p>The following example shows how to change all letters in <code class="inline">L</code> to upper case and
│ │ │ -then count them.</p><p>First the change to upper case:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Upcase</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="0351109166-1">(</span><span class="n">X</span><span class="p" data-group-id="0351109166-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w">  </span><span class="n">X</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="sc">$a</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0351109166-2">(</span><span class="n">X</span><span class="p" data-group-id="0351109166-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w">
│ │ │ +<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#mapfoldl/3"><code class="inline">lists:mapfoldl/3</code></a> simultaneously maps and folds over a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">mapfoldl</span><span class="p" data-group-id="1898042585-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1898042585-2">[</span><span class="n">Hd</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="1898042585-2">]</span><span class="p" data-group-id="1898042585-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1898042585-3">{</span><span class="n">R</span><span class="p">,</span><span class="n">Accu1</span><span class="p" data-group-id="1898042585-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="1898042585-4">(</span><span class="n">Hd</span><span class="p">,</span><span class="w"> </span><span class="n">Accu0</span><span class="p" data-group-id="1898042585-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1898042585-5">{</span><span class="n">Rs</span><span class="p">,</span><span class="n">Accu2</span><span class="p" data-group-id="1898042585-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">mapfoldl</span><span class="p" data-group-id="1898042585-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu1</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="1898042585-6">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1898042585-7">{</span><span class="p" data-group-id="1898042585-8">[</span><span class="n">R</span><span class="p">|</span><span class="n">Rs</span><span class="p" data-group-id="1898042585-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu2</span><span class="p" data-group-id="1898042585-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">mapfoldl</span><span class="p" data-group-id="1898042585-9">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1898042585-10">[</span><span class="p" data-group-id="1898042585-10">]</span><span class="p" data-group-id="1898042585-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1898042585-11">{</span><span class="p" data-group-id="1898042585-12">[</span><span class="p" data-group-id="1898042585-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Accu</span><span class="p" data-group-id="1898042585-11">}</span><span class="p">.</span></code></pre><p>The following example shows how to change all letters in <code class="inline">L</code> to upper case and
│ │ │ +then count them.</p><p>First the change to upper case:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Upcase</span><span class="w"> </span><span class="o">=</span><span class="w">  </span><span class="nf">fun</span><span class="p" data-group-id="6049532940-1">(</span><span class="n">X</span><span class="p" data-group-id="6049532940-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="sc">$a</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w">  </span><span class="n">X</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="sc">$z</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="sc">$A</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="sc">$a</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6049532940-2">(</span><span class="n">X</span><span class="p" data-group-id="6049532940-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │  &gt; </span><span class="n">Upcase_word</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ -</span><span class="nf">fun</span><span class="p" data-group-id="0351109166-3">(</span><span class="n">X</span><span class="p" data-group-id="0351109166-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="0351109166-4">(</span><span class="n">Upcase</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="0351109166-4">)</span><span class="w">
│ │ │ +</span><span class="nf">fun</span><span class="p" data-group-id="6049532940-3">(</span><span class="n">X</span><span class="p" data-group-id="6049532940-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="6049532940-4">(</span><span class="n">Upcase</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6049532940-4">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Upcase_word</span><span class="p" data-group-id="0351109166-5">(</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="0351109166-5">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="n">Upcase_word</span><span class="p" data-group-id="6049532940-5">(</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="6049532940-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;ERLANG&quot;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="0351109166-6">(</span><span class="n">Upcase_word</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="0351109166-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0351109166-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="0351109166-7">]</span></code></pre><p>Now, the fold and the map can be done at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">mapfoldl</span><span class="p" data-group-id="9873300908-1">(</span><span class="nf">fun</span><span class="p" data-group-id="9873300908-2">(</span><span class="n">Word</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="9873300908-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9873300908-3">{</span><span class="n">Upcase_word</span><span class="p" data-group-id="9873300908-4">(</span><span class="n">Word</span><span class="p" data-group-id="9873300908-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="9873300908-5">(</span><span class="n">Word</span><span class="p" data-group-id="9873300908-5">)</span><span class="p" data-group-id="9873300908-3">}</span><span class="w">
│ │ │ -</span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="9873300908-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9873300908-6">{</span><span class="p" data-group-id="9873300908-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="9873300908-7">]</span><span class="p">,</span><span class="mi">11</span><span class="p" data-group-id="9873300908-6">}</span></code></pre><h3 id="filter" class="section-heading">
│ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="6049532940-6">(</span><span class="n">Upcase_word</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6049532940-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6049532940-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="6049532940-7">]</span></code></pre><p>Now, the fold and the map can be done at the same time:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">mapfoldl</span><span class="p" data-group-id="7349341535-1">(</span><span class="nf">fun</span><span class="p" data-group-id="7349341535-2">(</span><span class="n">Word</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="7349341535-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7349341535-3">{</span><span class="n">Upcase_word</span><span class="p" data-group-id="7349341535-4">(</span><span class="n">Word</span><span class="p" data-group-id="7349341535-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="7349341535-5">(</span><span class="n">Word</span><span class="p" data-group-id="7349341535-5">)</span><span class="p" data-group-id="7349341535-3">}</span><span class="w">
│ │ │ +</span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7349341535-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7349341535-6">{</span><span class="p" data-group-id="7349341535-7">[</span><span class="s">&quot;I&quot;</span><span class="p">,</span><span class="s">&quot;LIKE&quot;</span><span class="p">,</span><span class="s">&quot;ERLANG&quot;</span><span class="p" data-group-id="7349341535-7">]</span><span class="p">,</span><span class="mi">11</span><span class="p" data-group-id="7349341535-6">}</span></code></pre><h3 id="filter" class="section-heading">
│ │ │    <a href="#filter" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">filter</span>
│ │ │  </h3>
│ │ │  <p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#filter/2"><code class="inline">lists:filter/2</code></a> takes a predicate of one argument and a list and returns all elements
│ │ │ -in the list that satisfy the predicate:</p><pre><code class="makeup erlang" translate="no"><span class="nf">filter</span><span class="p" data-group-id="3924191354-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3924191354-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3924191354-2">]</span><span class="p" data-group-id="3924191354-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="3924191354-3">(</span><span class="n">H</span><span class="p" data-group-id="3924191354-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3924191354-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">filter</span><span class="p" data-group-id="3924191354-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="3924191354-5">)</span><span class="p" data-group-id="3924191354-4">]</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="3924191354-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="3924191354-6">)</span><span class="w">
│ │ │ +in the list that satisfy the predicate:</p><pre><code class="makeup erlang" translate="no"><span class="nf">filter</span><span class="p" data-group-id="5419759465-1">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5419759465-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5419759465-2">]</span><span class="p" data-group-id="5419759465-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="5419759465-3">(</span><span class="n">H</span><span class="p" data-group-id="5419759465-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5419759465-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">filter</span><span class="p" data-group-id="5419759465-5">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="5419759465-5">)</span><span class="p" data-group-id="5419759465-4">]</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="5419759465-6">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="5419759465-6">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">filter</span><span class="p" data-group-id="3924191354-7">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3924191354-8">[</span><span class="p" data-group-id="3924191354-8">]</span><span class="p" data-group-id="3924191354-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3924191354-9">[</span><span class="p" data-group-id="3924191354-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="0197971020-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0197971020-2">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="0197971020-2">]</span><span class="p" data-group-id="0197971020-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0197971020-3">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="0197971020-3">]</span></code></pre><p>Combining maps and filters enables writing of very succinct code. For example,
│ │ │ +</span><span class="nf">filter</span><span class="p" data-group-id="5419759465-7">(</span><span class="n">F</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5419759465-8">[</span><span class="p" data-group-id="5419759465-8">]</span><span class="p" data-group-id="5419759465-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5419759465-9">[</span><span class="p" data-group-id="5419759465-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="3520075100-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3520075100-2">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="3520075100-2">]</span><span class="p" data-group-id="3520075100-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3520075100-3">[</span><span class="mi">500</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="3520075100-3">]</span></code></pre><p>Combining maps and filters enables writing of very succinct code. For example,
│ │ │  to define a set difference function <code class="inline">diff(L1, L2)</code> to be the difference between
│ │ │ -the lists <code class="inline">L1</code> and <code class="inline">L2</code>, the code can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">diff</span><span class="p" data-group-id="3276491662-1">(</span><span class="n">L1</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="3276491662-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">filter</span><span class="p" data-group-id="3276491662-2">(</span><span class="nf">fun</span><span class="p" data-group-id="3276491662-3">(</span><span class="n">X</span><span class="p" data-group-id="3276491662-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ow">not</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="3276491662-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="3276491662-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="3276491662-2">)</span><span class="p">.</span></code></pre><p>This gives the list of all elements in L1 that are not contained in L2.</p><p>The AND intersection of the list <code class="inline">L1</code> and <code class="inline">L2</code> is also easily defined:</p><pre><code class="makeup erlang" translate="no"><span class="nf">intersection</span><span class="p" data-group-id="6890452864-1">(</span><span class="n">L1</span><span class="p">,</span><span class="n">L2</span><span class="p" data-group-id="6890452864-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="6890452864-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6890452864-3">(</span><span class="n">X</span><span class="p" data-group-id="6890452864-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="6890452864-4">(</span><span class="n">X</span><span class="p">,</span><span class="n">L1</span><span class="p" data-group-id="6890452864-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="6890452864-2">)</span><span class="p">.</span></code></pre><h3 id="takewhile" class="section-heading">
│ │ │ +the lists <code class="inline">L1</code> and <code class="inline">L2</code>, the code can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">diff</span><span class="p" data-group-id="7515161874-1">(</span><span class="n">L1</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="7515161874-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">filter</span><span class="p" data-group-id="7515161874-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7515161874-3">(</span><span class="n">X</span><span class="p" data-group-id="7515161874-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ow">not</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="7515161874-4">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="7515161874-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="7515161874-2">)</span><span class="p">.</span></code></pre><p>This gives the list of all elements in L1 that are not contained in L2.</p><p>The AND intersection of the list <code class="inline">L1</code> and <code class="inline">L2</code> is also easily defined:</p><pre><code class="makeup erlang" translate="no"><span class="nf">intersection</span><span class="p" data-group-id="2033928875-1">(</span><span class="n">L1</span><span class="p">,</span><span class="n">L2</span><span class="p" data-group-id="2033928875-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">filter</span><span class="p" data-group-id="2033928875-2">(</span><span class="nf">fun</span><span class="p" data-group-id="2033928875-3">(</span><span class="n">X</span><span class="p" data-group-id="2033928875-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">member</span><span class="p" data-group-id="2033928875-4">(</span><span class="n">X</span><span class="p">,</span><span class="n">L1</span><span class="p" data-group-id="2033928875-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">L2</span><span class="p" data-group-id="2033928875-2">)</span><span class="p">.</span></code></pre><h3 id="takewhile" class="section-heading">
│ │ │    <a href="#takewhile" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">takewhile</span>
│ │ │  </h3>
│ │ │  <p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#takewhile/2"><code class="inline">lists:takewhile/2</code></a> takes elements <code class="inline">X</code> from a list <code class="inline">L</code> as long as the predicate
│ │ │ -<code class="inline">P(X)</code> is true:</p><pre><code class="makeup erlang" translate="no"><span class="nf">takewhile</span><span class="p" data-group-id="9911989401-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9911989401-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9911989401-2">]</span><span class="p" data-group-id="9911989401-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="9911989401-3">(</span><span class="n">H</span><span class="p" data-group-id="9911989401-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9911989401-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">takewhile</span><span class="p" data-group-id="9911989401-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9911989401-5">)</span><span class="p" data-group-id="9911989401-4">]</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9911989401-6">[</span><span class="p" data-group-id="9911989401-6">]</span><span class="w">
│ │ │ +<code class="inline">P(X)</code> is true:</p><pre><code class="makeup erlang" translate="no"><span class="nf">takewhile</span><span class="p" data-group-id="1066318176-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1066318176-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1066318176-2">]</span><span class="p" data-group-id="1066318176-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="1066318176-3">(</span><span class="n">H</span><span class="p" data-group-id="1066318176-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1066318176-4">[</span><span class="n">H</span><span class="p">|</span><span class="nf">takewhile</span><span class="p" data-group-id="1066318176-5">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="1066318176-5">)</span><span class="p" data-group-id="1066318176-4">]</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1066318176-6">[</span><span class="p" data-group-id="1066318176-6">]</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">takewhile</span><span class="p" data-group-id="9911989401-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9911989401-8">[</span><span class="p" data-group-id="9911989401-8">]</span><span class="p" data-group-id="9911989401-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9911989401-9">[</span><span class="p" data-group-id="9911989401-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">takewhile</span><span class="p" data-group-id="2165359783-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2165359783-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2165359783-2">]</span><span class="p" data-group-id="2165359783-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2165359783-3">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="2165359783-3">]</span></code></pre><h3 id="dropwhile" class="section-heading">
│ │ │ +</span><span class="nf">takewhile</span><span class="p" data-group-id="1066318176-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1066318176-8">[</span><span class="p" data-group-id="1066318176-8">]</span><span class="p" data-group-id="1066318176-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1066318176-9">[</span><span class="p" data-group-id="1066318176-9">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">takewhile</span><span class="p" data-group-id="8124806897-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8124806897-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8124806897-2">]</span><span class="p" data-group-id="8124806897-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8124806897-3">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="8124806897-3">]</span></code></pre><h3 id="dropwhile" class="section-heading">
│ │ │    <a href="#dropwhile" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">dropwhile</span>
│ │ │  </h3>
│ │ │ -<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#dropwhile/2"><code class="inline">lists:dropwhile/2</code></a> is the complement of <code class="inline">takewhile</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">dropwhile</span><span class="p" data-group-id="0050819992-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050819992-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0050819992-2">]</span><span class="p" data-group-id="0050819992-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="0050819992-3">(</span><span class="n">H</span><span class="p" data-group-id="0050819992-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">dropwhile</span><span class="p" data-group-id="0050819992-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="0050819992-4">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0050819992-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0050819992-5">]</span><span class="w">
│ │ │ +<p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#dropwhile/2"><code class="inline">lists:dropwhile/2</code></a> is the complement of <code class="inline">takewhile</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">dropwhile</span><span class="p" data-group-id="9473794979-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9473794979-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9473794979-2">]</span><span class="p" data-group-id="9473794979-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="9473794979-3">(</span><span class="n">H</span><span class="p" data-group-id="9473794979-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">dropwhile</span><span class="p" data-group-id="9473794979-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="9473794979-4">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9473794979-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="9473794979-5">]</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">dropwhile</span><span class="p" data-group-id="0050819992-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0050819992-7">[</span><span class="p" data-group-id="0050819992-7">]</span><span class="p" data-group-id="0050819992-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0050819992-8">[</span><span class="p" data-group-id="0050819992-8">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">dropwhile</span><span class="p" data-group-id="5843187110-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5843187110-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5843187110-2">]</span><span class="p" data-group-id="5843187110-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5843187110-3">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5843187110-3">]</span></code></pre><h3 id="splitwith" class="section-heading">
│ │ │ +</span><span class="nf">dropwhile</span><span class="p" data-group-id="9473794979-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9473794979-7">[</span><span class="p" data-group-id="9473794979-7">]</span><span class="p" data-group-id="9473794979-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9473794979-8">[</span><span class="p" data-group-id="9473794979-8">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">dropwhile</span><span class="p" data-group-id="7043343022-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7043343022-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7043343022-2">]</span><span class="p" data-group-id="7043343022-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7043343022-3">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7043343022-3">]</span></code></pre><h3 id="splitwith" class="section-heading">
│ │ │    <a href="#splitwith" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">splitwith</span>
│ │ │  </h3>
│ │ │  <p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#splitwith/2"><code class="inline">lists:splitwith/2</code></a> splits the list <code class="inline">L</code> into the two sublists <code class="inline">{L1, L2}</code>, where
│ │ │ -<code class="inline">L = takewhile(P, L)</code> and <code class="inline">L2 = dropwhile(P, L)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">splitwith</span><span class="p" data-group-id="4489360421-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4489360421-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">splitwith</span><span class="p" data-group-id="4489360421-2">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4489360421-3">[</span><span class="p" data-group-id="4489360421-3">]</span><span class="p" data-group-id="4489360421-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">L = takewhile(P, L)</code> and <code class="inline">L2 = dropwhile(P, L)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">splitwith</span><span class="p" data-group-id="5452844342-1">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5452844342-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">splitwith</span><span class="p" data-group-id="5452844342-2">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5452844342-3">[</span><span class="p" data-group-id="5452844342-3">]</span><span class="p" data-group-id="5452844342-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">splitwith</span><span class="p" data-group-id="4489360421-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4489360421-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4489360421-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4489360421-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="4489360421-6">(</span><span class="n">H</span><span class="p" data-group-id="4489360421-6">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">splitwith</span><span class="p" data-group-id="4489360421-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4489360421-8">[</span><span class="n">H</span><span class="p">|</span><span class="n">L</span><span class="p" data-group-id="4489360421-8">]</span><span class="p" data-group-id="4489360421-7">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4489360421-9">{</span><span class="nf">reverse</span><span class="p" data-group-id="4489360421-10">(</span><span class="n">L</span><span class="p" data-group-id="4489360421-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4489360421-11">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="4489360421-11">]</span><span class="p" data-group-id="4489360421-9">}</span><span class="w">
│ │ │ +</span><span class="nf">splitwith</span><span class="p" data-group-id="5452844342-4">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5452844342-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5452844342-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5452844342-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="5452844342-6">(</span><span class="n">H</span><span class="p" data-group-id="5452844342-6">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="ss">true</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">splitwith</span><span class="p" data-group-id="5452844342-7">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5452844342-8">[</span><span class="n">H</span><span class="p">|</span><span class="n">L</span><span class="p" data-group-id="5452844342-8">]</span><span class="p" data-group-id="5452844342-7">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5452844342-9">{</span><span class="nf">reverse</span><span class="p" data-group-id="5452844342-10">(</span><span class="n">L</span><span class="p" data-group-id="5452844342-10">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5452844342-11">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5452844342-11">]</span><span class="p" data-group-id="5452844342-9">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">splitwith</span><span class="p" data-group-id="4489360421-12">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4489360421-13">[</span><span class="p" data-group-id="4489360421-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4489360421-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4489360421-14">{</span><span class="nf">reverse</span><span class="p" data-group-id="4489360421-15">(</span><span class="n">L</span><span class="p" data-group-id="4489360421-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4489360421-16">[</span><span class="p" data-group-id="4489360421-16">]</span><span class="p" data-group-id="4489360421-14">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">splitwith</span><span class="p" data-group-id="0349029540-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0349029540-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="0349029540-2">]</span><span class="p" data-group-id="0349029540-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0349029540-3">{</span><span class="p" data-group-id="0349029540-4">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="0349029540-4">]</span><span class="p">,</span><span class="p" data-group-id="0349029540-5">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="0349029540-5">]</span><span class="p" data-group-id="0349029540-3">}</span></code></pre><h2 id="funs-returning-funs" class="section-heading">
│ │ │ +</span><span class="nf">splitwith</span><span class="p" data-group-id="5452844342-12">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5452844342-13">[</span><span class="p" data-group-id="5452844342-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="5452844342-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5452844342-14">{</span><span class="nf">reverse</span><span class="p" data-group-id="5452844342-15">(</span><span class="n">L</span><span class="p" data-group-id="5452844342-15">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5452844342-16">[</span><span class="p" data-group-id="5452844342-16">]</span><span class="p" data-group-id="5452844342-14">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">splitwith</span><span class="p" data-group-id="8809903730-1">(</span><span class="n">Big</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8809903730-2">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8809903730-2">]</span><span class="p" data-group-id="8809903730-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8809903730-3">{</span><span class="p" data-group-id="8809903730-4">[</span><span class="mi">200</span><span class="p">,</span><span class="mi">500</span><span class="p">,</span><span class="mi">45</span><span class="p" data-group-id="8809903730-4">]</span><span class="p">,</span><span class="p" data-group-id="8809903730-5">[</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">45</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8809903730-5">]</span><span class="p" data-group-id="8809903730-3">}</span></code></pre><h2 id="funs-returning-funs" class="section-heading">
│ │ │    <a href="#funs-returning-funs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Funs Returning Funs</span>
│ │ │  </h2>
│ │ │  <p>So far, only functions that take funs as arguments have been described. More
│ │ │  powerful functions, that themselves return funs, can also be written. The
│ │ │  following examples illustrate these type of functions.</p><h3 id="simple-higher-order-functions" class="section-heading">
│ │ │    <a href="#simple-higher-order-functions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Simple Higher Order Functions</span>
│ │ │  </h3>
│ │ │  <p><code class="inline">Adder(X)</code> is a function that given <code class="inline">X</code>, returns a new function <code class="inline">G</code> such that
│ │ │ -<code class="inline">G(K)</code> returns <code class="inline">K + X</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Adder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1233104232-1">(</span><span class="n">X</span><span class="p" data-group-id="1233104232-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1233104232-2">(</span><span class="n">Y</span><span class="p" data-group-id="1233104232-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">G(K)</code> returns <code class="inline">K + X</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Adder</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="2743351695-1">(</span><span class="n">X</span><span class="p" data-group-id="2743351695-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="2743351695-2">(</span><span class="n">Y</span><span class="p" data-group-id="2743351695-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Add6</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Adder</span><span class="p" data-group-id="1233104232-3">(</span><span class="mi">6</span><span class="p" data-group-id="1233104232-3">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="n">Add6</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Adder</span><span class="p" data-group-id="2743351695-3">(</span><span class="mi">6</span><span class="p" data-group-id="2743351695-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">6.72228031</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Add6</span><span class="p" data-group-id="1233104232-4">(</span><span class="mi">10</span><span class="p" data-group-id="1233104232-4">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="n">Add6</span><span class="p" data-group-id="2743351695-4">(</span><span class="mi">10</span><span class="p" data-group-id="2743351695-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">16</span></code></pre><h3 id="infinite-lists" class="section-heading">
│ │ │    <a href="#infinite-lists" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Infinite Lists</span>
│ │ │  </h3>
│ │ │ -<p>The idea is to write something like:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2450406159-1">(</span><span class="ss">lazy</span><span class="p" data-group-id="2450406159-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2450406159-2">(</span><span class="p" data-group-id="2450406159-3">[</span><span class="ss">ints_from</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2450406159-3">]</span><span class="p" data-group-id="2450406159-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">ints_from</span><span class="p" data-group-id="2450406159-4">(</span><span class="n">N</span><span class="p" data-group-id="2450406159-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">fun</span><span class="p" data-group-id="2450406159-5">(</span><span class="p" data-group-id="2450406159-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="2450406159-6">[</span><span class="n">N</span><span class="p">|</span><span class="nf">ints_from</span><span class="p" data-group-id="2450406159-7">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="2450406159-7">)</span><span class="p" data-group-id="2450406159-6">]</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Then proceed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">XX</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lazy</span><span class="p">:</span><span class="nf">ints_from</span><span class="p" data-group-id="9276634149-1">(</span><span class="mi">1</span><span class="p" data-group-id="9276634149-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>The idea is to write something like:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5415293421-1">(</span><span class="ss">lazy</span><span class="p" data-group-id="5415293421-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5415293421-2">(</span><span class="p" data-group-id="5415293421-3">[</span><span class="ss">ints_from</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5415293421-3">]</span><span class="p" data-group-id="5415293421-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">ints_from</span><span class="p" data-group-id="5415293421-4">(</span><span class="n">N</span><span class="p" data-group-id="5415293421-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">fun</span><span class="p" data-group-id="5415293421-5">(</span><span class="p" data-group-id="5415293421-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="5415293421-6">[</span><span class="n">N</span><span class="p">|</span><span class="nf">ints_from</span><span class="p" data-group-id="5415293421-7">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="5415293421-7">)</span><span class="p" data-group-id="5415293421-6">]</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Then proceed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">XX</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lazy</span><span class="p">:</span><span class="nf">ints_from</span><span class="p" data-group-id="7368281769-1">(</span><span class="mi">1</span><span class="p" data-group-id="7368281769-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">XX</span><span class="p" data-group-id="9276634149-2">(</span><span class="p" data-group-id="9276634149-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9276634149-3">[</span><span class="mi">1</span><span class="p">|</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="p" data-group-id="9276634149-3">]</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">hd</span><span class="p" data-group-id="9276634149-4">(</span><span class="n">XX</span><span class="p" data-group-id="9276634149-5">(</span><span class="p" data-group-id="9276634149-5">)</span><span class="p" data-group-id="9276634149-4">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="n">XX</span><span class="p" data-group-id="7368281769-2">(</span><span class="p" data-group-id="7368281769-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7368281769-3">[</span><span class="mi">1</span><span class="p">|</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="p" data-group-id="7368281769-3">]</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">hd</span><span class="p" data-group-id="7368281769-4">(</span><span class="n">XX</span><span class="p" data-group-id="7368281769-5">(</span><span class="p" data-group-id="7368281769-5">)</span><span class="p" data-group-id="7368281769-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tl</span><span class="p" data-group-id="9276634149-6">(</span><span class="n">XX</span><span class="p" data-group-id="9276634149-7">(</span><span class="p" data-group-id="9276634149-7">)</span><span class="p" data-group-id="9276634149-6">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">tl</span><span class="p" data-group-id="7368281769-6">(</span><span class="n">XX</span><span class="p" data-group-id="7368281769-7">(</span><span class="p" data-group-id="7368281769-7">)</span><span class="p" data-group-id="7368281769-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">lazy</span><span class="p">.</span><span class="mf">0.29874839</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">hd</span><span class="p" data-group-id="9276634149-8">(</span><span class="n">Y</span><span class="p" data-group-id="9276634149-9">(</span><span class="p" data-group-id="9276634149-9">)</span><span class="p" data-group-id="9276634149-8">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">hd</span><span class="p" data-group-id="7368281769-8">(</span><span class="n">Y</span><span class="p" data-group-id="7368281769-9">(</span><span class="p" data-group-id="7368281769-9">)</span><span class="p" data-group-id="7368281769-8">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">2</span></code></pre><p>And so on. This is an example of &quot;lazy embedding&quot;.</p><h3 id="parsing" class="section-heading">
│ │ │    <a href="#parsing" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Parsing</span>
│ │ │  </h3>
│ │ │ -<p>The following examples show parsers of the following type:</p><pre><code class="makeup erlang" translate="no"><span class="n">Parser</span><span class="p" data-group-id="7995932100-1">(</span><span class="n">Toks</span><span class="p" data-group-id="7995932100-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7995932100-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tree</span><span class="p">,</span><span class="w"> </span><span class="n">Toks1</span><span class="p" data-group-id="7995932100-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">fail</span></code></pre><p><code class="inline">Toks</code> is the list of tokens to be parsed. A successful parse returns
│ │ │ +<p>The following examples show parsers of the following type:</p><pre><code class="makeup erlang" translate="no"><span class="n">Parser</span><span class="p" data-group-id="1940904847-1">(</span><span class="n">Toks</span><span class="p" data-group-id="1940904847-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1940904847-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Tree</span><span class="p">,</span><span class="w"> </span><span class="n">Toks1</span><span class="p" data-group-id="1940904847-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">fail</span></code></pre><p><code class="inline">Toks</code> is the list of tokens to be parsed. A successful parse returns
│ │ │  <code class="inline">{ok, Tree, Toks1}</code>.</p><ul><li><code class="inline">Tree</code> is a parse tree.</li><li><code class="inline">Toks1</code> is a tail of <code class="inline">Tree</code> that contains symbols encountered after the
│ │ │  structure that was correctly parsed.</li></ul><p>An unsuccessful parse returns <code class="inline">fail</code>.</p><p>The following example illustrates a simple, functional parser that parses the
│ │ │  grammar:</p><pre><code class="text">(a | b) &amp; (c | d)</code></pre><p>The following code defines a function <code class="inline">pconst(X)</code> in the module <code class="inline">funparse</code>,
│ │ │ -which returns a fun that parses a list of tokens:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pconst</span><span class="p" data-group-id="3953495618-1">(</span><span class="n">X</span><span class="p" data-group-id="3953495618-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3953495618-2">(</span><span class="n">T</span><span class="p" data-group-id="3953495618-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +which returns a fun that parses a list of tokens:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pconst</span><span class="p" data-group-id="3143174470-1">(</span><span class="n">X</span><span class="p" data-group-id="3143174470-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3143174470-2">(</span><span class="n">T</span><span class="p" data-group-id="3143174470-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │         </span><span class="k">case</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -           </span><span class="p" data-group-id="3953495618-3">[</span><span class="n">X</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="3953495618-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3953495618-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3953495618-5">{</span><span class="ss">const</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3953495618-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="3953495618-4">}</span><span class="p">;</span><span class="w">
│ │ │ +           </span><span class="p" data-group-id="3143174470-3">[</span><span class="n">X</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="3143174470-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3143174470-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3143174470-5">{</span><span class="ss">const</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3143174470-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="3143174470-4">}</span><span class="p">;</span><span class="w">
│ │ │             </span><span class="p">_</span><span class="w">      </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">fail</span><span class="w">
│ │ │         </span><span class="k">end</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>This function can be used as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">pconst</span><span class="p" data-group-id="8843015171-1">(</span><span class="ss">a</span><span class="p" data-group-id="8843015171-1">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>This function can be used as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">pconst</span><span class="p" data-group-id="2665110550-1">(</span><span class="ss">a</span><span class="p" data-group-id="2665110550-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">funparse</span><span class="p">.</span><span class="mf">0.22674075</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">P1</span><span class="p" data-group-id="8843015171-2">(</span><span class="p" data-group-id="8843015171-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8843015171-3">]</span><span class="p" data-group-id="8843015171-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8843015171-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="8843015171-5">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="8843015171-5">}</span><span class="p">,</span><span class="p" data-group-id="8843015171-6">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8843015171-6">]</span><span class="p" data-group-id="8843015171-4">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">P1</span><span class="p" data-group-id="8843015171-7">(</span><span class="p" data-group-id="8843015171-8">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="8843015171-8">]</span><span class="p" data-group-id="8843015171-7">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="n">P1</span><span class="p" data-group-id="2665110550-2">(</span><span class="p" data-group-id="2665110550-3">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="2665110550-3">]</span><span class="p" data-group-id="2665110550-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2665110550-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="2665110550-5">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="2665110550-5">}</span><span class="p">,</span><span class="p" data-group-id="2665110550-6">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="2665110550-6">]</span><span class="p" data-group-id="2665110550-4">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">P1</span><span class="p" data-group-id="2665110550-7">(</span><span class="p" data-group-id="2665110550-8">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="2665110550-8">]</span><span class="p" data-group-id="2665110550-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">fail</span></code></pre><p>Next, the two higher order functions <code class="inline">pand</code> and <code class="inline">por</code> are defined. They combine
│ │ │ -primitive parsers to produce more complex parsers.</p><p>First <code class="inline">pand</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pand</span><span class="p" data-group-id="8041034790-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="8041034790-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="8041034790-2">(</span><span class="n">T</span><span class="p" data-group-id="8041034790-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="8041034790-3">(</span><span class="n">T</span><span class="p" data-group-id="8041034790-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="8041034790-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="8041034790-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="8041034790-5">(</span><span class="n">T1</span><span class="p" data-group-id="8041034790-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="8041034790-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="8041034790-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                        </span><span class="p" data-group-id="8041034790-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8041034790-8">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p" data-group-id="8041034790-8">}</span><span class="p" data-group-id="8041034790-7">}</span><span class="p">;</span><span class="w">
│ │ │ +primitive parsers to produce more complex parsers.</p><p>First <code class="inline">pand</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pand</span><span class="p" data-group-id="2718216293-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="2718216293-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2718216293-2">(</span><span class="n">T</span><span class="p" data-group-id="2718216293-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="2718216293-3">(</span><span class="n">T</span><span class="p" data-group-id="2718216293-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="2718216293-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2718216293-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="2718216293-5">(</span><span class="n">T1</span><span class="p" data-group-id="2718216293-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="2718216293-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="2718216293-6">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                        </span><span class="p" data-group-id="2718216293-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2718216293-8">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p" data-group-id="2718216293-8">}</span><span class="p" data-group-id="2718216293-7">}</span><span class="p">;</span><span class="w">
│ │ │                      </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                          </span><span class="ss">fail</span><span class="w">
│ │ │                  </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="ss">fail</span><span class="w">
│ │ │          </span><span class="k">end</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Given a parser <code class="inline">P1</code> for grammar <code class="inline">G1</code>, and a parser <code class="inline">P2</code> for grammar <code class="inline">G2</code>,
│ │ │  <code class="inline">pand(P1, P2)</code> returns a parser for the grammar, which consists of sequences of
│ │ │  tokens that satisfy <code class="inline">G1</code>, followed by sequences of tokens that satisfy <code class="inline">G2</code>.</p><p><code class="inline">por(P1, P2)</code> returns a parser for the language described by the grammar <code class="inline">G1</code> or
│ │ │ -<code class="inline">G2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">por</span><span class="p" data-group-id="5683711081-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="5683711081-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="5683711081-2">(</span><span class="n">T</span><span class="p" data-group-id="5683711081-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="5683711081-3">(</span><span class="n">T</span><span class="p" data-group-id="5683711081-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="5683711081-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5683711081-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="p" data-group-id="5683711081-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5683711081-6">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="n">R</span><span class="p" data-group-id="5683711081-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5683711081-5">}</span><span class="p">;</span><span class="w">
│ │ │ +<code class="inline">G2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">por</span><span class="p" data-group-id="2039784757-1">(</span><span class="n">P1</span><span class="p">,</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="2039784757-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2039784757-2">(</span><span class="n">T</span><span class="p" data-group-id="2039784757-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="k">case</span><span class="w"> </span><span class="n">P1</span><span class="p" data-group-id="2039784757-3">(</span><span class="n">T</span><span class="p" data-group-id="2039784757-3">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="2039784757-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2039784757-4">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                </span><span class="p" data-group-id="2039784757-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2039784757-6">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="n">R</span><span class="p" data-group-id="2039784757-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2039784757-5">}</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="5683711081-7">(</span><span class="n">T</span><span class="p" data-group-id="5683711081-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="5683711081-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5683711081-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                        </span><span class="p" data-group-id="5683711081-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5683711081-10">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="n">R1</span><span class="p" data-group-id="5683711081-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="5683711081-9">}</span><span class="p">;</span><span class="w">
│ │ │ +                </span><span class="k">case</span><span class="w"> </span><span class="n">P2</span><span class="p" data-group-id="2039784757-7">(</span><span class="n">T</span><span class="p" data-group-id="2039784757-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="2039784757-8">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2039784757-8">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                        </span><span class="p" data-group-id="2039784757-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2039784757-10">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="n">R1</span><span class="p" data-group-id="2039784757-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2039784757-9">}</span><span class="p">;</span><span class="w">
│ │ │                      </span><span class="ss">fail</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                          </span><span class="ss">fail</span><span class="w">
│ │ │                  </span><span class="k">end</span><span class="w">
│ │ │          </span><span class="k">end</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The original problem was to parse the grammar <code class="inline">(a | b) &amp; (c | d)</code>. The following
│ │ │ -code addresses this problem:</p><pre><code class="makeup erlang" translate="no"><span class="nf">grammar</span><span class="p" data-group-id="2619452551-1">(</span><span class="p" data-group-id="2619452551-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">pand</span><span class="p" data-group-id="2619452551-2">(</span><span class="w">
│ │ │ -         </span><span class="nf">por</span><span class="p" data-group-id="2619452551-3">(</span><span class="nf">pconst</span><span class="p" data-group-id="2619452551-4">(</span><span class="ss">a</span><span class="p" data-group-id="2619452551-4">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="2619452551-5">(</span><span class="ss">b</span><span class="p" data-group-id="2619452551-5">)</span><span class="p" data-group-id="2619452551-3">)</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="nf">por</span><span class="p" data-group-id="2619452551-6">(</span><span class="nf">pconst</span><span class="p" data-group-id="2619452551-7">(</span><span class="ss">c</span><span class="p" data-group-id="2619452551-7">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="2619452551-8">(</span><span class="ss">d</span><span class="p" data-group-id="2619452551-8">)</span><span class="p" data-group-id="2619452551-6">)</span><span class="p" data-group-id="2619452551-2">)</span><span class="p">.</span></code></pre><p>The following code adds a parser interface to the grammar:</p><pre><code class="makeup erlang" translate="no"><span class="nf">parse</span><span class="p" data-group-id="1644255768-1">(</span><span class="n">List</span><span class="p" data-group-id="1644255768-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1644255768-2">(</span><span class="nf">grammar</span><span class="p" data-group-id="1644255768-3">(</span><span class="p" data-group-id="1644255768-3">)</span><span class="p" data-group-id="1644255768-2">)</span><span class="p" data-group-id="1644255768-4">(</span><span class="n">List</span><span class="p" data-group-id="1644255768-4">)</span><span class="p">.</span></code></pre><p>The parser can be tested as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3777077050-1">(</span><span class="p" data-group-id="3777077050-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3777077050-2">]</span><span class="p" data-group-id="3777077050-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3777077050-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3777077050-4">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3777077050-5">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3777077050-6">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3777077050-6">}</span><span class="p" data-group-id="3777077050-5">}</span><span class="p">,</span><span class="p" data-group-id="3777077050-7">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3777077050-8">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3777077050-8">}</span><span class="p" data-group-id="3777077050-7">}</span><span class="p" data-group-id="3777077050-4">}</span><span class="p" data-group-id="3777077050-3">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3777077050-9">(</span><span class="p" data-group-id="3777077050-10">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3777077050-10">]</span><span class="p" data-group-id="3777077050-9">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3777077050-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3777077050-12">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3777077050-13">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3777077050-14">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3777077050-14">}</span><span class="p" data-group-id="3777077050-13">}</span><span class="p">,</span><span class="p" data-group-id="3777077050-15">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3777077050-16">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3777077050-16">}</span><span class="p" data-group-id="3777077050-15">}</span><span class="p" data-group-id="3777077050-12">}</span><span class="p" data-group-id="3777077050-11">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3777077050-17">(</span><span class="p" data-group-id="3777077050-18">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3777077050-18">]</span><span class="p" data-group-id="3777077050-17">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3777077050-19">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3777077050-20">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3777077050-21">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3777077050-22">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3777077050-22">}</span><span class="p" data-group-id="3777077050-21">}</span><span class="p">,</span><span class="p" data-group-id="3777077050-23">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3777077050-24">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3777077050-24">}</span><span class="p" data-group-id="3777077050-23">}</span><span class="p" data-group-id="3777077050-20">}</span><span class="p" data-group-id="3777077050-19">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3777077050-25">(</span><span class="p" data-group-id="3777077050-26">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3777077050-26">]</span><span class="p" data-group-id="3777077050-25">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3777077050-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3777077050-28">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3777077050-29">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3777077050-30">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3777077050-30">}</span><span class="p" data-group-id="3777077050-29">}</span><span class="p">,</span><span class="p" data-group-id="3777077050-31">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3777077050-32">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3777077050-32">}</span><span class="p" data-group-id="3777077050-31">}</span><span class="p" data-group-id="3777077050-28">}</span><span class="p" data-group-id="3777077050-27">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3777077050-33">(</span><span class="p" data-group-id="3777077050-34">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3777077050-34">]</span><span class="p" data-group-id="3777077050-33">)</span><span class="p">.</span><span class="w">
│ │ │ +code addresses this problem:</p><pre><code class="makeup erlang" translate="no"><span class="nf">grammar</span><span class="p" data-group-id="2058614075-1">(</span><span class="p" data-group-id="2058614075-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">pand</span><span class="p" data-group-id="2058614075-2">(</span><span class="w">
│ │ │ +         </span><span class="nf">por</span><span class="p" data-group-id="2058614075-3">(</span><span class="nf">pconst</span><span class="p" data-group-id="2058614075-4">(</span><span class="ss">a</span><span class="p" data-group-id="2058614075-4">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="2058614075-5">(</span><span class="ss">b</span><span class="p" data-group-id="2058614075-5">)</span><span class="p" data-group-id="2058614075-3">)</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="nf">por</span><span class="p" data-group-id="2058614075-6">(</span><span class="nf">pconst</span><span class="p" data-group-id="2058614075-7">(</span><span class="ss">c</span><span class="p" data-group-id="2058614075-7">)</span><span class="p">,</span><span class="w"> </span><span class="nf">pconst</span><span class="p" data-group-id="2058614075-8">(</span><span class="ss">d</span><span class="p" data-group-id="2058614075-8">)</span><span class="p" data-group-id="2058614075-6">)</span><span class="p" data-group-id="2058614075-2">)</span><span class="p">.</span></code></pre><p>The following code adds a parser interface to the grammar:</p><pre><code class="makeup erlang" translate="no"><span class="nf">parse</span><span class="p" data-group-id="1040729597-1">(</span><span class="n">List</span><span class="p" data-group-id="1040729597-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1040729597-2">(</span><span class="nf">grammar</span><span class="p" data-group-id="1040729597-3">(</span><span class="p" data-group-id="1040729597-3">)</span><span class="p" data-group-id="1040729597-2">)</span><span class="p" data-group-id="1040729597-4">(</span><span class="n">List</span><span class="p" data-group-id="1040729597-4">)</span><span class="p">.</span></code></pre><p>The parser can be tested as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3082162726-1">(</span><span class="p" data-group-id="3082162726-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3082162726-2">]</span><span class="p" data-group-id="3082162726-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3082162726-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3082162726-4">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3082162726-5">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3082162726-6">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3082162726-6">}</span><span class="p" data-group-id="3082162726-5">}</span><span class="p">,</span><span class="p" data-group-id="3082162726-7">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3082162726-8">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3082162726-8">}</span><span class="p" data-group-id="3082162726-7">}</span><span class="p" data-group-id="3082162726-4">}</span><span class="p" data-group-id="3082162726-3">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3082162726-9">(</span><span class="p" data-group-id="3082162726-10">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3082162726-10">]</span><span class="p" data-group-id="3082162726-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3082162726-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3082162726-12">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3082162726-13">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3082162726-14">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3082162726-14">}</span><span class="p" data-group-id="3082162726-13">}</span><span class="p">,</span><span class="p" data-group-id="3082162726-15">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3082162726-16">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3082162726-16">}</span><span class="p" data-group-id="3082162726-15">}</span><span class="p" data-group-id="3082162726-12">}</span><span class="p" data-group-id="3082162726-11">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3082162726-17">(</span><span class="p" data-group-id="3082162726-18">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3082162726-18">]</span><span class="p" data-group-id="3082162726-17">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3082162726-19">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3082162726-20">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3082162726-21">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3082162726-22">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3082162726-22">}</span><span class="p" data-group-id="3082162726-21">}</span><span class="p">,</span><span class="p" data-group-id="3082162726-23">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3082162726-24">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3082162726-24">}</span><span class="p" data-group-id="3082162726-23">}</span><span class="p" data-group-id="3082162726-20">}</span><span class="p" data-group-id="3082162726-19">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3082162726-25">(</span><span class="p" data-group-id="3082162726-26">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3082162726-26">]</span><span class="p" data-group-id="3082162726-25">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3082162726-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3082162726-28">{</span><span class="ss">&#39;and&#39;</span><span class="p">,</span><span class="p" data-group-id="3082162726-29">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3082162726-30">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3082162726-30">}</span><span class="p" data-group-id="3082162726-29">}</span><span class="p">,</span><span class="p" data-group-id="3082162726-31">{</span><span class="ss">&#39;or&#39;</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="p" data-group-id="3082162726-32">{</span><span class="ss">const</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="3082162726-32">}</span><span class="p" data-group-id="3082162726-31">}</span><span class="p" data-group-id="3082162726-28">}</span><span class="p" data-group-id="3082162726-27">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nc">funparse</span><span class="p">:</span><span class="nf">parse</span><span class="p" data-group-id="3082162726-33">(</span><span class="p" data-group-id="3082162726-34">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3082162726-34">]</span><span class="p" data-group-id="3082162726-33">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">fail</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="prog_ex_records.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/gen_server_concepts.html
│ │ │ @@ -157,63 +157,63 @@
│ │ │    <a href="#example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Example</span>
│ │ │  </h2>
│ │ │  <p>An example of a simple server written in plain Erlang is provided in
│ │ │  <a href="design_principles.html#ch1">Overview</a>. The server can be reimplemented using
│ │ │ -<code class="inline">gen_server</code>, resulting in this callback module:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3919362012-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="3919362012-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="3919362012-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="3919362012-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">gen_server</code>, resulting in this callback module:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9228988736-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="9228988736-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9228988736-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="9228988736-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3919362012-3">(</span><span class="p" data-group-id="3919362012-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3919362012-4">]</span><span class="p" data-group-id="3919362012-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3919362012-5">(</span><span class="p" data-group-id="3919362012-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3919362012-6">]</span><span class="p" data-group-id="3919362012-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3919362012-7">(</span><span class="p" data-group-id="3919362012-8">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3919362012-8">]</span><span class="p" data-group-id="3919362012-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9228988736-3">(</span><span class="p" data-group-id="9228988736-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9228988736-4">]</span><span class="p" data-group-id="9228988736-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9228988736-5">(</span><span class="p" data-group-id="9228988736-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9228988736-6">]</span><span class="p" data-group-id="9228988736-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9228988736-7">(</span><span class="p" data-group-id="9228988736-8">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9228988736-8">]</span><span class="p" data-group-id="9228988736-7">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="3919362012-9">(</span><span class="p" data-group-id="3919362012-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3919362012-10">(</span><span class="p" data-group-id="3919362012-11">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3919362012-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3919362012-12">[</span><span class="p" data-group-id="3919362012-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3919362012-13">[</span><span class="p" data-group-id="3919362012-13">]</span><span class="p" data-group-id="3919362012-10">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="9228988736-9">(</span><span class="p" data-group-id="9228988736-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9228988736-10">(</span><span class="p" data-group-id="9228988736-11">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="9228988736-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9228988736-12">[</span><span class="p" data-group-id="9228988736-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9228988736-13">[</span><span class="p" data-group-id="9228988736-13">]</span><span class="p" data-group-id="9228988736-10">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="3919362012-14">(</span><span class="p" data-group-id="3919362012-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="3919362012-15">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="3919362012-15">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="9228988736-14">(</span><span class="p" data-group-id="9228988736-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="9228988736-15">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="9228988736-15">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="3919362012-16">(</span><span class="n">Ch</span><span class="p" data-group-id="3919362012-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="3919362012-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3919362012-18">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3919362012-18">}</span><span class="p" data-group-id="3919362012-17">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="9228988736-16">(</span><span class="n">Ch</span><span class="p" data-group-id="9228988736-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="9228988736-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9228988736-18">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="9228988736-18">}</span><span class="p" data-group-id="9228988736-17">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3919362012-19">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="3919362012-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3919362012-20">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="3919362012-21">(</span><span class="p" data-group-id="3919362012-21">)</span><span class="p" data-group-id="3919362012-20">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="9228988736-19">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="9228988736-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9228988736-20">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="9228988736-21">(</span><span class="p" data-group-id="9228988736-21">)</span><span class="p" data-group-id="9228988736-20">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="3919362012-22">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3919362012-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3919362012-23">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3919362012-23">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="3919362012-24">(</span><span class="n">Chs</span><span class="p" data-group-id="3919362012-24">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3919362012-25">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3919362012-25">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="9228988736-22">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="9228988736-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9228988736-23">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="9228988736-23">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="9228988736-24">(</span><span class="n">Chs</span><span class="p" data-group-id="9228988736-24">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9228988736-25">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="9228988736-25">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="3919362012-26">(</span><span class="p" data-group-id="3919362012-27">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3919362012-27">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3919362012-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="3919362012-28">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3919362012-28">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3919362012-29">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3919362012-29">}</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><h2 id="starting-a-gen_server" class="section-heading">
│ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="9228988736-26">(</span><span class="p" data-group-id="9228988736-27">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="9228988736-27">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="9228988736-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="9228988736-28">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="9228988736-28">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9228988736-29">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="9228988736-29">}</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><h2 id="starting-a-gen_server" class="section-heading">
│ │ │    <a href="#starting-a-gen_server" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting a Gen_Server</span>
│ │ │  </h2>
│ │ │  <p>In the example in the previous section, <code class="inline">gen_server</code> is started by calling
│ │ │ -<code class="inline">ch3:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="7358206783-1">(</span><span class="p" data-group-id="7358206783-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="7358206783-2">(</span><span class="p" data-group-id="7358206783-3">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="7358206783-3">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7358206783-4">[</span><span class="p" data-group-id="7358206783-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7358206783-5">[</span><span class="p" data-group-id="7358206783-5">]</span><span class="p" data-group-id="7358206783-2">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7358206783-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="7358206783-6">}</span></code></pre><p><code class="inline">start_link/0</code> calls function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a>.  This function
│ │ │ +<code class="inline">ch3:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="3637105309-1">(</span><span class="p" data-group-id="3637105309-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3637105309-2">(</span><span class="p" data-group-id="3637105309-3">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3637105309-3">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3637105309-4">[</span><span class="p" data-group-id="3637105309-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3637105309-5">[</span><span class="p" data-group-id="3637105309-5">]</span><span class="p" data-group-id="3637105309-2">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3637105309-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="3637105309-6">}</span></code></pre><p><code class="inline">start_link/0</code> calls function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a>.  This function
│ │ │  spawns and links to a new process, a <code class="inline">gen_server</code>.</p><ul><li><p>The first argument, <code class="inline">{local, ch3}</code>, specifies the name.
│ │ │  The gen_server is then locally registered as <code class="inline">ch3</code>.</p><p>If the name is omitted, the <code class="inline">gen_server</code> is not registered. Instead its pid
│ │ │  must be used. The name can also be given as <code class="inline">{global, Name}</code>, in which case
│ │ │  the <code class="inline">gen_server</code> is registered using <a href="../../lib/kernel-10.2.7.2/doc/html/global.html#register_name/2"><code class="inline">global:register_name/2</code></a>.</p></li><li><p>The second argument, <code class="inline">ch3</code>, is the name of the callback module, which is
│ │ │  the module where the callback functions are located.</p><p>The interface functions (<code class="inline">start_link/0</code>, <code class="inline">alloc/0</code>, and <code class="inline">free/1</code>) are located
│ │ │  in the same module as the callback functions (<code class="inline">init/1</code>, <code class="inline">handle_call/3</code>, and
│ │ │  <code class="inline">handle_cast/2</code>). It is usually good programming practice to have the code
│ │ │  corresponding to one process contained in a single module.</p></li><li><p>The third argument, <code class="inline">[]</code>, is a term that is passed as is to the callback
│ │ │  function <code class="inline">init</code>. Here, <code class="inline">init</code> does not need any indata and ignores the
│ │ │  argument.</p></li><li><p>The fourth argument, <code class="inline">[]</code>, is a list of options. See <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html"><code class="inline">gen_server</code></a>
│ │ │  for the available options.</p></li></ul><p>If name registration succeeds, the new <code class="inline">gen_server</code> process calls the callback
│ │ │  function <code class="inline">ch3:init([])</code>. <code class="inline">init</code> is expected to return <code class="inline">{ok, State}</code>, where
│ │ │  <code class="inline">State</code> is the internal state of the <code class="inline">gen_server</code>. In this case, the state is
│ │ │ -the available channels.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="3490097118-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="3490097118-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3490097118-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="3490097118-3">(</span><span class="p" data-group-id="3490097118-3">)</span><span class="p" data-group-id="3490097118-2">}</span><span class="p">.</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a> is synchronous. It does not return until the
│ │ │ +the available channels.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="4419693351-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="4419693351-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4419693351-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="4419693351-3">(</span><span class="p" data-group-id="4419693351-3">)</span><span class="p" data-group-id="4419693351-2">}</span><span class="p">.</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a> is synchronous. It does not return until the
│ │ │  <code class="inline">gen_server</code> has been initialized and is ready to receive requests.</p><p><a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/4</code></a> must be used if the <code class="inline">gen_server</code> is part of
│ │ │  a supervision tree, meaning that it was started by a supervisor. There
│ │ │  is another function, <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#start/4"><code class="inline">gen_server:start/4</code></a>, to start a standalone
│ │ │  <code class="inline">gen_server</code> that is not part of a supervision tree.</p><h2 id="synchronous-requests-call" class="section-heading">
│ │ │    <a href="#synchronous-requests-call" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -221,32 +221,32 @@
│ │ │  </h2>
│ │ │  <p>The synchronous request <code class="inline">alloc()</code> is implemented using <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#call/2"><code class="inline">gen_server:call/2</code></a>:</p><pre><code class="text">alloc() -&gt;
│ │ │      gen_server:call(ch3, alloc).</code></pre><p><code class="inline">ch3</code> is the name of the <code class="inline">gen_server</code> and must agree with the name
│ │ │  used to start it. <code class="inline">alloc</code> is the actual request.</p><p>The request is made into a message and sent to the <code class="inline">gen_server</code>.
│ │ │  When the request is received, the <code class="inline">gen_server</code> calls
│ │ │  <code class="inline">handle_call(Request, From, State)</code>, which is expected to return
│ │ │  a tuple <code class="inline">{reply,Reply,State1}</code>. <code class="inline">Reply</code> is the reply that is to be sent back
│ │ │ -to the client, and <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="7933913819-1">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="7933913819-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7933913819-2">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="7933913819-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="7933913819-3">(</span><span class="n">Chs</span><span class="p" data-group-id="7933913819-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7933913819-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="7933913819-4">}</span><span class="p">.</span></code></pre><p>In this case, the reply is the allocated channel <code class="inline">Ch</code> and the new state is the
│ │ │ +to the client, and <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_call</span><span class="p" data-group-id="0058924826-1">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="0058924826-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0058924826-2">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="0058924826-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="0058924826-3">(</span><span class="n">Chs</span><span class="p" data-group-id="0058924826-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0058924826-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="0058924826-4">}</span><span class="p">.</span></code></pre><p>In this case, the reply is the allocated channel <code class="inline">Ch</code> and the new state is the
│ │ │  set of remaining available channels <code class="inline">Chs2</code>.</p><p>Thus, the call <code class="inline">ch3:alloc()</code> returns the allocated channel <code class="inline">Ch</code> and the
│ │ │  <code class="inline">gen_server</code> then waits for new requests, now with an updated list of
│ │ │  available channels.</p><h2 id="asynchronous-requests-cast" class="section-heading">
│ │ │    <a href="#asynchronous-requests-cast" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Asynchronous Requests - Cast</span>
│ │ │  </h2>
│ │ │ -<p>The asynchronous request <code class="inline">free(Ch)</code> is implemented using <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#cast/2"><code class="inline">gen_server:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">free</span><span class="p" data-group-id="4191643343-1">(</span><span class="n">Ch</span><span class="p" data-group-id="4191643343-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="4191643343-2">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4191643343-3">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4191643343-3">}</span><span class="p" data-group-id="4191643343-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch3</code> is the name of the <code class="inline">gen_server</code>. <code class="inline">{free, Ch}</code> is the actual request.</p><p>The request is made into a message and sent to the <code class="inline">gen_server</code>.
│ │ │ +<p>The asynchronous request <code class="inline">free(Ch)</code> is implemented using <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#cast/2"><code class="inline">gen_server:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">free</span><span class="p" data-group-id="5741047162-1">(</span><span class="n">Ch</span><span class="p" data-group-id="5741047162-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="5741047162-2">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5741047162-3">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="5741047162-3">}</span><span class="p" data-group-id="5741047162-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch3</code> is the name of the <code class="inline">gen_server</code>. <code class="inline">{free, Ch}</code> is the actual request.</p><p>The request is made into a message and sent to the <code class="inline">gen_server</code>.
│ │ │  <code class="inline">cast</code>, and thus <code class="inline">free</code>, then returns <code class="inline">ok</code>.</p><p>When the request is received, the <code class="inline">gen_server</code> calls
│ │ │  <code class="inline">handle_cast(Request, State)</code>, which is expected to return a tuple
│ │ │ -<code class="inline">{noreply,State1}</code>. <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_cast</span><span class="p" data-group-id="1878776976-1">(</span><span class="p" data-group-id="1878776976-2">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="1878776976-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="1878776976-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="1878776976-3">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="1878776976-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1878776976-4">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="1878776976-4">}</span><span class="p">.</span></code></pre><p>In this case, the new state is the updated list of available channels <code class="inline">Chs2</code>.
│ │ │ +<code class="inline">{noreply,State1}</code>. <code class="inline">State1</code> is a new value for the state of the <code class="inline">gen_server</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_cast</span><span class="p" data-group-id="7168177352-1">(</span><span class="p" data-group-id="7168177352-2">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="7168177352-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="7168177352-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="7168177352-3">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="7168177352-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7168177352-4">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="7168177352-4">}</span><span class="p">.</span></code></pre><p>In this case, the new state is the updated list of available channels <code class="inline">Chs2</code>.
│ │ │  The <code class="inline">gen_server</code> is now ready for new requests.</p><h2 id="stopping" class="section-heading">
│ │ │    <a href="#stopping" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Stopping</span>
│ │ │  </h2>
│ │ │  <h3 id="in-a-supervision-tree" class="section-heading">
│ │ │ @@ -257,69 +257,69 @@
│ │ │  </h3>
│ │ │  <p>If the <code class="inline">gen_server</code> is part of a supervision tree, no stop function is needed.
│ │ │  The <code class="inline">gen_server</code> is automatically terminated by its supervisor.  Exactly how
│ │ │  this is done is defined by a <a href="sup_princ.html#shutdown">shutdown strategy</a>
│ │ │  set in the supervisor.</p><p>If it is necessary to clean up before termination, the shutdown strategy
│ │ │  must be a time-out value and the <code class="inline">gen_server</code> must be set to trap exit signals
│ │ │  in function <code class="inline">init</code>. When ordered to shutdown, the <code class="inline">gen_server</code> then calls
│ │ │ -the callback function <code class="inline">terminate(shutdown, State)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="9486713612-1">(</span><span class="n">Args</span><span class="p" data-group-id="9486713612-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +the callback function <code class="inline">terminate(shutdown, State)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="6857650773-1">(</span><span class="n">Args</span><span class="p" data-group-id="6857650773-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="9486713612-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="9486713612-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="6857650773-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6857650773-2">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9486713612-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9486713612-3">}</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6857650773-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6857650773-3">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="9486713612-4">(</span><span class="ss">shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="9486713612-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="6857650773-4">(</span><span class="ss">shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6857650773-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Code for cleaning up here</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h3 id="standalone-gen_servers" class="section-heading">
│ │ │    <a href="#standalone-gen_servers" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Standalone Gen_Servers</span>
│ │ │  </h3>
│ │ │  <p>If the <code class="inline">gen_server</code> is not part of a supervision tree, a stop function
│ │ │  can be useful, for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">export</span><span class="p" data-group-id="7758878233-1">(</span><span class="p" data-group-id="7758878233-2">[</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7758878233-2">]</span><span class="p" data-group-id="7758878233-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">export</span><span class="p" data-group-id="6460268387-1">(</span><span class="p" data-group-id="6460268387-2">[</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6460268387-2">]</span><span class="p" data-group-id="6460268387-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="7758878233-3">(</span><span class="p" data-group-id="7758878233-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="7758878233-4">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p" data-group-id="7758878233-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="6460268387-3">(</span><span class="p" data-group-id="6460268387-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="6460268387-4">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p" data-group-id="6460268387-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="7758878233-5">(</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7758878233-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7758878233-6">{</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7758878233-6">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="7758878233-7">(</span><span class="p" data-group-id="7758878233-8">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="7758878233-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7758878233-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="6460268387-5">(</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6460268387-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6460268387-6">{</span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6460268387-6">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="6460268387-7">(</span><span class="p" data-group-id="6460268387-8">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="6460268387-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6460268387-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="7758878233-9">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7758878233-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="6460268387-9">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6460268387-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The callback function handling the <code class="inline">stop</code> request returns a tuple
│ │ │  <code class="inline">{stop,normal,State1}</code>, where <code class="inline">normal</code> specifies that it is
│ │ │  a normal termination and <code class="inline">State1</code> is a new value for the state
│ │ │  of the <code class="inline">gen_server</code>.  This causes the <code class="inline">gen_server</code> to call
│ │ │  <code class="inline">terminate(normal, State1)</code> and then it terminates gracefully.</p><h2 id="handling-other-messages" class="section-heading">
│ │ │    <a href="#handling-other-messages" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Handling Other Messages</span>
│ │ │  </h2>
│ │ │  <p>If the <code class="inline">gen_server</code> is to be able to receive other messages than requests,
│ │ │  the callback function <code class="inline">handle_info(Info, State)</code> must be implemented
│ │ │  to handle them.  Examples of other messages are exit messages,
│ │ │  if the <code class="inline">gen_server</code> is linked to other processes than the supervisor
│ │ │ -and it is trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="6204061262-1">(</span><span class="p" data-group-id="6204061262-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="6204061262-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="6204061262-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +and it is trapping exit signals.</p><pre><code class="makeup erlang" translate="no"><span class="nf">handle_info</span><span class="p" data-group-id="2700237711-1">(</span><span class="p" data-group-id="2700237711-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2700237711-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="2700237711-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Code to handle exits here.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6204061262-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="6204061262-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="6551752389-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="6551752389-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2700237711-3">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">State1</span><span class="p" data-group-id="2700237711-3">}</span><span class="p">.</span></code></pre><p>The final function to implement is <code class="inline">code_change/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">code_change</span><span class="p" data-group-id="7509689164-1">(</span><span class="n">OldVsn</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="7509689164-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Code to convert state (and more) during code change.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6551752389-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="6551752389-2">}</span><span class="p">.</span></code></pre>
│ │ │ +    </span><span class="p" data-group-id="7509689164-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NewState</span><span class="p" data-group-id="7509689164-2">}</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="design_principles.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/included_applications.html
│ │ │ @@ -161,75 +161,75 @@
│ │ │  belonging to the primary application.</p><h2 id="specifying-included-applications" class="section-heading">
│ │ │    <a href="#specifying-included-applications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Specifying Included Applications</span>
│ │ │  </h2>
│ │ │  <p>Which applications to include is defined by the <code class="inline">included_applications</code> key in
│ │ │ -the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9663812267-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9663812267-2">[</span><span class="p" data-group-id="9663812267-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="9663812267-3">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9663812267-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="9663812267-4">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9663812267-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9663812267-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="9663812267-6">]</span><span class="p" data-group-id="9663812267-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9663812267-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9663812267-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="9663812267-8">]</span><span class="p" data-group-id="9663812267-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9663812267-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9663812267-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="9663812267-10">]</span><span class="p" data-group-id="9663812267-9">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9663812267-11">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9663812267-12">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="9663812267-12">]</span><span class="p" data-group-id="9663812267-11">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9663812267-13">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9663812267-14">{</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="9663812267-15">[</span><span class="p" data-group-id="9663812267-15">]</span><span class="p" data-group-id="9663812267-14">}</span><span class="p" data-group-id="9663812267-13">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9663812267-16">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9663812267-17">[</span><span class="p" data-group-id="9663812267-18">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="9663812267-18">}</span><span class="p" data-group-id="9663812267-17">]</span><span class="p" data-group-id="9663812267-16">}</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9663812267-2">]</span><span class="p" data-group-id="9663812267-1">}</span><span class="p">.</span></code></pre><h2 id="synchronizing-processes-during-startup" class="section-heading">
│ │ │ +the <code class="inline">.app</code> file:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8688979960-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8688979960-2">[</span><span class="p" data-group-id="8688979960-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="8688979960-3">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8688979960-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="8688979960-4">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8688979960-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688979960-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="8688979960-6">]</span><span class="p" data-group-id="8688979960-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8688979960-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688979960-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="8688979960-8">]</span><span class="p" data-group-id="8688979960-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8688979960-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688979960-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="8688979960-10">]</span><span class="p" data-group-id="8688979960-9">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8688979960-11">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688979960-12">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="8688979960-12">]</span><span class="p" data-group-id="8688979960-11">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8688979960-13">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688979960-14">{</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="8688979960-15">[</span><span class="p" data-group-id="8688979960-15">]</span><span class="p" data-group-id="8688979960-14">}</span><span class="p" data-group-id="8688979960-13">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8688979960-16">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8688979960-17">[</span><span class="p" data-group-id="8688979960-18">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="8688979960-18">}</span><span class="p" data-group-id="8688979960-17">]</span><span class="p" data-group-id="8688979960-16">}</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="8688979960-2">]</span><span class="p" data-group-id="8688979960-1">}</span><span class="p">.</span></code></pre><h2 id="synchronizing-processes-during-startup" class="section-heading">
│ │ │    <a href="#synchronizing-processes-during-startup" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Synchronizing Processes during Startup</span>
│ │ │  </h2>
│ │ │  <p>The supervisor tree of an included application is started as part of the
│ │ │  supervisor tree of the including application. If there is a need for
│ │ │  synchronization between processes in the including and included applications,
│ │ │  this can be achieved by using <em>start phases</em>.</p><p>Start phases are defined by the <code class="inline">start_phases</code> key in the <code class="inline">.app</code> file as a list
│ │ │  of tuples <code class="inline">{Phase,PhaseArgs}</code>, where <code class="inline">Phase</code> is an atom and <code class="inline">PhaseArgs</code> is a
│ │ │  term.</p><p>The value of the <code class="inline">mod</code> key of the including application must be set to
│ │ │  <code class="inline">{application_starter,[Module,StartArgs]}</code>, where <code class="inline">Module</code> as usual is the
│ │ │  application callback module. <code class="inline">StartArgs</code> is a term provided as argument to the
│ │ │ -callback function <code class="inline">Module:start/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2616853461-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2616853461-2">[</span><span class="p" data-group-id="2616853461-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="2616853461-3">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="2616853461-4">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="2616853461-6">]</span><span class="p" data-group-id="2616853461-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="2616853461-8">]</span><span class="p" data-group-id="2616853461-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="2616853461-10">]</span><span class="p" data-group-id="2616853461-9">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-11">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-12">[</span><span class="p" data-group-id="2616853461-13">{</span><span class="ss">init</span><span class="p">,</span><span class="p" data-group-id="2616853461-14">[</span><span class="p" data-group-id="2616853461-14">]</span><span class="p" data-group-id="2616853461-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-15">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="2616853461-16">[</span><span class="p" data-group-id="2616853461-16">]</span><span class="p" data-group-id="2616853461-15">}</span><span class="p" data-group-id="2616853461-12">]</span><span class="p" data-group-id="2616853461-11">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-17">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-18">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="2616853461-18">]</span><span class="p" data-group-id="2616853461-17">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-19">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-20">{</span><span class="ss">application_starter</span><span class="p">,</span><span class="p" data-group-id="2616853461-21">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="2616853461-22">[</span><span class="p" data-group-id="2616853461-22">]</span><span class="p" data-group-id="2616853461-21">]</span><span class="p" data-group-id="2616853461-20">}</span><span class="p" data-group-id="2616853461-19">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-23">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-24">[</span><span class="p" data-group-id="2616853461-25">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="2616853461-25">}</span><span class="p" data-group-id="2616853461-24">]</span><span class="p" data-group-id="2616853461-23">}</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2616853461-2">]</span><span class="p" data-group-id="2616853461-1">}</span><span class="p">.</span><span class="w">
│ │ │ +callback function <code class="inline">Module:start/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5707612884-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5707612884-2">[</span><span class="p" data-group-id="5707612884-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Tree application&quot;</span><span class="p" data-group-id="5707612884-3">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="5707612884-4">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-6">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">prim_app_server</span><span class="p" data-group-id="5707612884-6">]</span><span class="p" data-group-id="5707612884-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-8">[</span><span class="ss">prim_app_server</span><span class="p" data-group-id="5707612884-8">]</span><span class="p" data-group-id="5707612884-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-9">{</span><span class="ss">included_applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-10">[</span><span class="ss">incl_app</span><span class="p" data-group-id="5707612884-10">]</span><span class="p" data-group-id="5707612884-9">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-11">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-12">[</span><span class="p" data-group-id="5707612884-13">{</span><span class="ss">init</span><span class="p">,</span><span class="p" data-group-id="5707612884-14">[</span><span class="p" data-group-id="5707612884-14">]</span><span class="p" data-group-id="5707612884-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-15">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="5707612884-16">[</span><span class="p" data-group-id="5707612884-16">]</span><span class="p" data-group-id="5707612884-15">}</span><span class="p" data-group-id="5707612884-12">]</span><span class="p" data-group-id="5707612884-11">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-17">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-18">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="5707612884-18">]</span><span class="p" data-group-id="5707612884-17">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-19">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-20">{</span><span class="ss">application_starter</span><span class="p">,</span><span class="p" data-group-id="5707612884-21">[</span><span class="ss">prim_app_cb</span><span class="p">,</span><span class="p" data-group-id="5707612884-22">[</span><span class="p" data-group-id="5707612884-22">]</span><span class="p" data-group-id="5707612884-21">]</span><span class="p" data-group-id="5707612884-20">}</span><span class="p" data-group-id="5707612884-19">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-23">{</span><span class="ss">env</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-24">[</span><span class="p" data-group-id="5707612884-25">{</span><span class="ss">file</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;/usr/local/log&quot;</span><span class="p" data-group-id="5707612884-25">}</span><span class="p" data-group-id="5707612884-24">]</span><span class="p" data-group-id="5707612884-23">}</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5707612884-2">]</span><span class="p" data-group-id="5707612884-1">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="p" data-group-id="2616853461-26">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2616853461-27">[</span><span class="p" data-group-id="2616853461-28">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Included application&quot;</span><span class="p" data-group-id="2616853461-28">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-29">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="2616853461-29">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-30">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-31">[</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_server</span><span class="p" data-group-id="2616853461-31">]</span><span class="p" data-group-id="2616853461-30">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-32">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-33">[</span><span class="p" data-group-id="2616853461-33">]</span><span class="p" data-group-id="2616853461-32">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-34">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-35">[</span><span class="p" data-group-id="2616853461-36">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="2616853461-37">[</span><span class="p" data-group-id="2616853461-37">]</span><span class="p" data-group-id="2616853461-36">}</span><span class="p" data-group-id="2616853461-35">]</span><span class="p" data-group-id="2616853461-34">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-38">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-39">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="2616853461-39">]</span><span class="p" data-group-id="2616853461-38">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2616853461-40">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2616853461-41">{</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="p" data-group-id="2616853461-42">[</span><span class="p" data-group-id="2616853461-42">]</span><span class="p" data-group-id="2616853461-41">}</span><span class="p" data-group-id="2616853461-40">}</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2616853461-27">]</span><span class="p" data-group-id="2616853461-26">}</span><span class="p">.</span></code></pre><p>When starting a primary application with included applications, the primary
│ │ │ +</span><span class="p" data-group-id="5707612884-26">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5707612884-27">[</span><span class="p" data-group-id="5707612884-28">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Included application&quot;</span><span class="p" data-group-id="5707612884-28">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-29">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="5707612884-29">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-30">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-31">[</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">incl_app_server</span><span class="p" data-group-id="5707612884-31">]</span><span class="p" data-group-id="5707612884-30">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-32">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-33">[</span><span class="p" data-group-id="5707612884-33">]</span><span class="p" data-group-id="5707612884-32">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-34">{</span><span class="ss">start_phases</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-35">[</span><span class="p" data-group-id="5707612884-36">{</span><span class="ss">go</span><span class="p">,</span><span class="p" data-group-id="5707612884-37">[</span><span class="p" data-group-id="5707612884-37">]</span><span class="p" data-group-id="5707612884-36">}</span><span class="p" data-group-id="5707612884-35">]</span><span class="p" data-group-id="5707612884-34">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-38">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-39">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="5707612884-39">]</span><span class="p" data-group-id="5707612884-38">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5707612884-40">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5707612884-41">{</span><span class="ss">incl_app_cb</span><span class="p">,</span><span class="p" data-group-id="5707612884-42">[</span><span class="p" data-group-id="5707612884-42">]</span><span class="p" data-group-id="5707612884-41">}</span><span class="p" data-group-id="5707612884-40">}</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5707612884-27">]</span><span class="p" data-group-id="5707612884-26">}</span><span class="p">.</span></code></pre><p>When starting a primary application with included applications, the primary
│ │ │  application is started the normal way, that is:</p><ul><li>The application controller creates an application master for the application</li><li>The application master calls <code class="inline">Module:start(normal, StartArgs)</code> to start the
│ │ │  top supervisor.</li></ul><p>Then, for the primary application and each included application in top-down,
│ │ │  left-to-right order, the application master calls
│ │ │  <code class="inline">Module:start_phase(Phase, Type, PhaseArgs)</code> for each phase defined for the
│ │ │  primary application, in that order. If a phase is not defined for an included
│ │ │  application, the function is not called for this phase and application.</p><p>The following requirements apply to the <code class="inline">.app</code> file for an included application:</p><ul><li>The <code class="inline">{mod, {Module,StartArgs}}</code> option must be included. This option is used
│ │ │  to find the callback module <code class="inline">Module</code> of the application. <code class="inline">StartArgs</code> is
│ │ │  ignored, as <code class="inline">Module:start/2</code> is called only for the primary application.</li><li>If the included application itself contains included applications, instead the
│ │ │  <code class="inline">{mod, {application_starter, [Module,StartArgs]}}</code> option must be included.</li><li>The <code class="inline">{start_phases, [{Phase,PhaseArgs}]}</code> option must be included, and the set
│ │ │  of specified phases must be a subset of the set of phases specified for the
│ │ │  primary application.</li></ul><p>When starting <code class="inline">prim_app</code> as defined above, the application controller calls the
│ │ │  following callback functions before <code class="inline">application:start(prim_app)</code> returns a
│ │ │ -value:</p><pre><code class="makeup erlang" translate="no"><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5534009424-1">(</span><span class="ss">prim_app</span><span class="p" data-group-id="5534009424-1">)</span><span class="w">
│ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="5534009424-2">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5534009424-3">[</span><span class="p" data-group-id="5534009424-3">]</span><span class="p" data-group-id="5534009424-2">)</span><span class="w">
│ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="5534009424-4">(</span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5534009424-5">[</span><span class="p" data-group-id="5534009424-5">]</span><span class="p" data-group-id="5534009424-4">)</span><span class="w">
│ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="5534009424-6">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5534009424-7">[</span><span class="p" data-group-id="5534009424-7">]</span><span class="p" data-group-id="5534009424-6">)</span><span class="w">
│ │ │ - </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">incl_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="5534009424-8">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5534009424-9">[</span><span class="p" data-group-id="5534009424-9">]</span><span class="p" data-group-id="5534009424-8">)</span><span class="w">
│ │ │ +value:</p><pre><code class="makeup erlang" translate="no"><span class="nc">application</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4630438346-1">(</span><span class="ss">prim_app</span><span class="p" data-group-id="4630438346-1">)</span><span class="w">
│ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start</span><span class="p" data-group-id="4630438346-2">(</span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4630438346-3">[</span><span class="p" data-group-id="4630438346-3">]</span><span class="p" data-group-id="4630438346-2">)</span><span class="w">
│ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="4630438346-4">(</span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4630438346-5">[</span><span class="p" data-group-id="4630438346-5">]</span><span class="p" data-group-id="4630438346-4">)</span><span class="w">
│ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">prim_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="4630438346-6">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4630438346-7">[</span><span class="p" data-group-id="4630438346-7">]</span><span class="p" data-group-id="4630438346-6">)</span><span class="w">
│ │ │ + </span><span class="p">=&gt;</span><span class="w"> </span><span class="nc">incl_app_cb</span><span class="p">:</span><span class="nf">start_phase</span><span class="p" data-group-id="4630438346-8">(</span><span class="ss">go</span><span class="p">,</span><span class="w"> </span><span class="ss">normal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4630438346-9">[</span><span class="p" data-group-id="4630438346-9">]</span><span class="p" data-group-id="4630438346-8">)</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="applications.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/install-win32.html
│ │ │ @@ -295,15 +295,15 @@
│ │ │  </span><span class="gp unselectable">$ </span><span class="">cd erts/emulator
│ │ │  </span><span class="gp unselectable">$ </span><span class="">make debug
│ │ │  </span><span class="gp unselectable">$ </span><span class="">cd ../etc
│ │ │  </span><span class="gp unselectable">$ </span><span class="">make debug
│ │ │  </span></code></pre><p>and sometimes</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP
│ │ │  </span><span class="gp unselectable">$ </span><span class="">make local_setup
│ │ │  </span></code></pre><p>So now when you run <code class="inline">$ERL_TOP/erl.exe</code>, you should have a debug compiled
│ │ │ -emulator, which you will see if you do a:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="9972713095-1">(</span><span class="ss">system_version</span><span class="p" data-group-id="9972713095-1">)</span><span class="p">.</span></code></pre><p>in the erlang shell. If the returned string contains <code class="inline">[debug]</code>, you
│ │ │ +emulator, which you will see if you do a:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="3416121754-1">(</span><span class="ss">system_version</span><span class="p" data-group-id="3416121754-1">)</span><span class="p">.</span></code></pre><p>in the erlang shell. If the returned string contains <code class="inline">[debug]</code>, you
│ │ │  got a debug compiled emulator.</p><p>To hack the erlang libraries, you simply do a <code class="inline">make opt</code> in the
│ │ │  specific &quot;applications&quot; directory, like:</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP/lib/stdlib
│ │ │  </span><span class="gp unselectable">$ </span><span class="">make opt
│ │ │  </span></code></pre><p>or even in the source directory...</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP/lib/stdlib/src
│ │ │  </span><span class="gp unselectable">$ </span><span class="">make opt
│ │ │  </span></code></pre><p>Note that you're expected to have a fresh Erlang in your path when
│ │ │  doing this, preferably the plain 27 you have built in the previous
│ │ │ @@ -318,19 +318,19 @@
│ │ │  </span><span class="">:$ERL_TOP/erts/etc/win32/wsl_tools:$ERL_TOP/bootstrap/bin:$PATH
│ │ │  </span></code></pre><p>That should make it possible to rebuild any library without hassle...</p><p>If you want to copy a library (an application) newly built, to a
│ │ │  release area, you do like with the emulator:</p><pre><code class="makeup shell" translate="no"><span class="gp unselectable">$ </span><span class="">cd $ERL_TOP/lib/stdlib
│ │ │  </span><span class="gp unselectable">$ </span><span class="">make TESTROOT=/tmp/erlang_release release
│ │ │  </span></code></pre><p>Remember that:</p><ul><li><p>  Windows specific C-code goes in the <code class="inline">$ERL_TOP/erts/emulator/sys/win32</code>,
│ │ │  <code class="inline">$ERL_TOP/erts/emulator/drivers/win32</code> or <code class="inline">$ERL_TOP/erts/etc/win32</code>.</p></li><li><p>  Windows specific erlang code should be used conditionally and the
│ │ │  host OS tested in <em>runtime</em>, the exactly same beam files should be
│ │ │ -distributed for every platform! So write code like:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">os</span><span class="p">:</span><span class="nf">type</span><span class="p" data-group-id="0384611254-1">(</span><span class="p" data-group-id="0384611254-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0384611254-2">{</span><span class="ss">win32</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0384611254-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nf">do_windows_specific</span><span class="p" data-group-id="0384611254-3">(</span><span class="p" data-group-id="0384611254-3">)</span><span class="p">;</span><span class="w">
│ │ │ +distributed for every platform! So write code like:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">os</span><span class="p">:</span><span class="nf">type</span><span class="p" data-group-id="3521666338-1">(</span><span class="p" data-group-id="3521666338-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3521666338-2">{</span><span class="ss">win32</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="3521666338-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nf">do_windows_specific</span><span class="p" data-group-id="3521666338-3">(</span><span class="p" data-group-id="3521666338-3">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Other</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nf">do_fallback_or_exit</span><span class="p" data-group-id="0384611254-4">(</span><span class="p" data-group-id="0384611254-4">)</span><span class="w">
│ │ │ +        </span><span class="nf">do_fallback_or_exit</span><span class="p" data-group-id="3521666338-4">(</span><span class="p" data-group-id="3521666338-4">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">,</span></code></pre></li></ul><p>That's basically all you need to get going.</p><h2 id="frequently-asked-questions" class="section-heading">
│ │ │    <a href="#frequently-asked-questions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Frequently Asked Questions</span>
│ │ │  </h2>
│ │ │  <ul><li><p>  Q: So, now I can build Erlang using GCC on Windows?</p><p>A: No, unfortunately not. You'll need Microsoft's Visual C++
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/list_comprehensions.html
│ │ │ @@ -117,33 +117,33 @@
│ │ │  
│ │ │  <h2 id="simple-examples" class="section-heading">
│ │ │    <a href="#simple-examples" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Simple Examples</span>
│ │ │  </h2>
│ │ │ -<p>This section starts with a simple example, showing a generator and a filter:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="8105986926-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="8105986926-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8105986926-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="8105986926-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8105986926-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8105986926-3">]</span></code></pre><p>This is read as follows: The list of X such that X is taken from the list
│ │ │ +<p>This section starts with a simple example, showing a generator and a filter:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="1537480187-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="1537480187-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="1537480187-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1537480187-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1537480187-3">[</span><span class="ss">a</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="1537480187-3">]</span></code></pre><p>This is read as follows: The list of X such that X is taken from the list
│ │ │  <code class="inline">[1,2,a,...]</code> and X is greater than 3.</p><p>The notation <code class="inline">X &lt;- [1,2,a,...]</code> is a generator and the expression <code class="inline">X &gt; 3</code> is a
│ │ │  filter.</p><p>An additional filter, <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_integer/1"><code class="inline">is_integer(X)</code></a>, can be added to
│ │ │ -restrict the result to integers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="6979583118-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="6979583118-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="6979583118-2">]</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6979583118-3">(</span><span class="n">X</span><span class="p" data-group-id="6979583118-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="6979583118-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6979583118-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="6979583118-4">]</span></code></pre><p>Generators can be combined. For example, the Cartesian product of two lists can
│ │ │ -be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="9319911439-1">[</span><span class="p" data-group-id="9319911439-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9319911439-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9319911439-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9319911439-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9319911439-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9319911439-4">]</span><span class="p" data-group-id="9319911439-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9319911439-5">[</span><span class="p" data-group-id="9319911439-6">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="9319911439-6">}</span><span class="p">,</span><span class="p" data-group-id="9319911439-7">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9319911439-7">}</span><span class="p">,</span><span class="p" data-group-id="9319911439-8">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="9319911439-8">}</span><span class="p">,</span><span class="p" data-group-id="9319911439-9">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9319911439-9">}</span><span class="p">,</span><span class="p" data-group-id="9319911439-10">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="9319911439-10">}</span><span class="p">,</span><span class="p" data-group-id="9319911439-11">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9319911439-11">}</span><span class="p" data-group-id="9319911439-5">]</span></code></pre><h2 id="quick-sort" class="section-heading">
│ │ │ +restrict the result to integers:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="6469706583-1">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="6469706583-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="6469706583-2">]</span><span class="p">,</span><span class="w"> </span><span class="nf">is_integer</span><span class="p" data-group-id="6469706583-3">(</span><span class="n">X</span><span class="p" data-group-id="6469706583-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="6469706583-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6469706583-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="6469706583-4">]</span></code></pre><p>Generators can be combined. For example, the Cartesian product of two lists can
│ │ │ +be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="8324184214-1">[</span><span class="p" data-group-id="8324184214-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8324184214-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="8324184214-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8324184214-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="8324184214-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8324184214-4">]</span><span class="p" data-group-id="8324184214-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8324184214-5">[</span><span class="p" data-group-id="8324184214-6">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="8324184214-6">}</span><span class="p">,</span><span class="p" data-group-id="8324184214-7">{</span><span class="mi">1</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8324184214-7">}</span><span class="p">,</span><span class="p" data-group-id="8324184214-8">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="8324184214-8">}</span><span class="p">,</span><span class="p" data-group-id="8324184214-9">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8324184214-9">}</span><span class="p">,</span><span class="p" data-group-id="8324184214-10">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="8324184214-10">}</span><span class="p">,</span><span class="p" data-group-id="8324184214-11">{</span><span class="mi">3</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="8324184214-11">}</span><span class="p" data-group-id="8324184214-5">]</span></code></pre><h2 id="quick-sort" class="section-heading">
│ │ │    <a href="#quick-sort" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Quick Sort</span>
│ │ │  </h2>
│ │ │ -<p>The well-known quick sort routine can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sort</span><span class="p" data-group-id="6340647063-1">(</span><span class="p" data-group-id="6340647063-2">[</span><span class="p" data-group-id="6340647063-2">]</span><span class="p" data-group-id="6340647063-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6340647063-3">[</span><span class="p" data-group-id="6340647063-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">sort</span><span class="p" data-group-id="6340647063-4">(</span><span class="p" data-group-id="6340647063-5">[</span><span class="p">_</span><span class="p" data-group-id="6340647063-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="6340647063-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">L</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">sort</span><span class="p" data-group-id="6340647063-6">(</span><span class="p" data-group-id="6340647063-7">[</span><span class="n">Pivot</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6340647063-7">]</span><span class="p" data-group-id="6340647063-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">sort</span><span class="p" data-group-id="6340647063-8">(</span><span class="p" data-group-id="6340647063-9">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="6340647063-9">]</span><span class="p" data-group-id="6340647063-8">)</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6340647063-10">[</span><span class="n">Pivot</span><span class="p" data-group-id="6340647063-10">]</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ -    </span><span class="nf">sort</span><span class="p" data-group-id="6340647063-11">(</span><span class="p" data-group-id="6340647063-12">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="6340647063-12">]</span><span class="p" data-group-id="6340647063-11">)</span><span class="p">.</span></code></pre><p>The expression <code class="inline">[X || X &lt;- T, X &lt; Pivot]</code> is the list of all elements in <code class="inline">T</code>
│ │ │ +<p>The well-known quick sort routine can be written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sort</span><span class="p" data-group-id="0274739081-1">(</span><span class="p" data-group-id="0274739081-2">[</span><span class="p" data-group-id="0274739081-2">]</span><span class="p" data-group-id="0274739081-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0274739081-3">[</span><span class="p" data-group-id="0274739081-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">sort</span><span class="p" data-group-id="0274739081-4">(</span><span class="p" data-group-id="0274739081-5">[</span><span class="p">_</span><span class="p" data-group-id="0274739081-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="0274739081-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">L</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">sort</span><span class="p" data-group-id="0274739081-6">(</span><span class="p" data-group-id="0274739081-7">[</span><span class="n">Pivot</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0274739081-7">]</span><span class="p" data-group-id="0274739081-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">sort</span><span class="p" data-group-id="0274739081-8">(</span><span class="p" data-group-id="0274739081-9">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="0274739081-9">]</span><span class="p" data-group-id="0274739081-8">)</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0274739081-10">[</span><span class="n">Pivot</span><span class="p" data-group-id="0274739081-10">]</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ +    </span><span class="nf">sort</span><span class="p" data-group-id="0274739081-11">(</span><span class="p" data-group-id="0274739081-12">[</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="n">Pivot</span><span class="p" data-group-id="0274739081-12">]</span><span class="p" data-group-id="0274739081-11">)</span><span class="p">.</span></code></pre><p>The expression <code class="inline">[X || X &lt;- T, X &lt; Pivot]</code> is the list of all elements in <code class="inline">T</code>
│ │ │  that are less than <code class="inline">Pivot</code>.</p><p><code class="inline">[X || X &lt;- T, X &gt;= Pivot]</code> is the list of all elements in <code class="inline">T</code> that are greater
│ │ │  than or equal to <code class="inline">Pivot</code>.</p><p>With the algorithm above, a list is sorted as follows:</p><ul><li>A list with zero or one element is trivially sorted.</li><li>For lists with more than one element:<ol><li>The first element in the list is isolated as the pivot element.</li><li>The remaining list is partitioned into two sublists, such that:</li></ol><ul><li>The first sublist contains all elements that are smaller than the pivot
│ │ │  element.</li><li>The second sublist contains all elements that are greater than or equal to
│ │ │  the pivot element.</li></ul><ol><li>The sublists are recursively sorted by the same algorithm and the results
│ │ │  are combined, resulting in a list consisting of:</li></ol><ul><li>All elements from the first sublist, that is all elements smaller than the
│ │ │  pivot element, in sorted order.</li><li>The pivot element.</li><li>All elements from the second sublist, that is all elements greater than or
│ │ │  equal to the pivot element, in sorted order.</li></ul></li></ul><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>While the sorting algorithm as shown above serves as a nice example to
│ │ │ @@ -151,93 +151,93 @@
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html"><code class="inline">lists</code></a> module contains sorting functions that are implemented in a more
│ │ │  efficient way.</p></section><h2 id="permutations" class="section-heading">
│ │ │    <a href="#permutations" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Permutations</span>
│ │ │  </h2>
│ │ │ -<p>The following example generates all permutations of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">perms</span><span class="p" data-group-id="1528267412-1">(</span><span class="p" data-group-id="1528267412-2">[</span><span class="p" data-group-id="1528267412-2">]</span><span class="p" data-group-id="1528267412-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1528267412-3">[</span><span class="p" data-group-id="1528267412-4">[</span><span class="p" data-group-id="1528267412-4">]</span><span class="p" data-group-id="1528267412-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">perms</span><span class="p" data-group-id="1528267412-5">(</span><span class="n">L</span><span class="p" data-group-id="1528267412-5">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1528267412-6">[</span><span class="p" data-group-id="1528267412-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1528267412-7">]</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">H</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nf">perms</span><span class="p" data-group-id="1528267412-8">(</span><span class="n">L</span><span class="o">--</span><span class="p" data-group-id="1528267412-9">[</span><span class="n">H</span><span class="p" data-group-id="1528267412-9">]</span><span class="p" data-group-id="1528267412-8">)</span><span class="p" data-group-id="1528267412-6">]</span><span class="p">.</span></code></pre><p>This takes <code class="inline">H</code> from <code class="inline">L</code> in all possible ways. The result is the set of all lists
│ │ │ +<p>The following example generates all permutations of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="nf">perms</span><span class="p" data-group-id="3141948095-1">(</span><span class="p" data-group-id="3141948095-2">[</span><span class="p" data-group-id="3141948095-2">]</span><span class="p" data-group-id="3141948095-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3141948095-3">[</span><span class="p" data-group-id="3141948095-4">[</span><span class="p" data-group-id="3141948095-4">]</span><span class="p" data-group-id="3141948095-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">perms</span><span class="p" data-group-id="3141948095-5">(</span><span class="n">L</span><span class="p" data-group-id="3141948095-5">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3141948095-6">[</span><span class="p" data-group-id="3141948095-7">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="3141948095-7">]</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">H</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nf">perms</span><span class="p" data-group-id="3141948095-8">(</span><span class="n">L</span><span class="o">--</span><span class="p" data-group-id="3141948095-9">[</span><span class="n">H</span><span class="p" data-group-id="3141948095-9">]</span><span class="p" data-group-id="3141948095-8">)</span><span class="p" data-group-id="3141948095-6">]</span><span class="p">.</span></code></pre><p>This takes <code class="inline">H</code> from <code class="inline">L</code> in all possible ways. The result is the set of all lists
│ │ │  <code class="inline">[H|T]</code>, where <code class="inline">T</code> is the set of all possible permutations of <code class="inline">L</code>, with <code class="inline">H</code>
│ │ │ -removed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">perms</span><span class="p" data-group-id="1168755160-1">(</span><span class="p" data-group-id="1168755160-2">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="1168755160-2">]</span><span class="p" data-group-id="1168755160-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1168755160-3">[</span><span class="p" data-group-id="1168755160-4">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="1168755160-4">]</span><span class="p">,</span><span class="p" data-group-id="1168755160-5">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="1168755160-5">]</span><span class="p">,</span><span class="p" data-group-id="1168755160-6">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="1168755160-6">]</span><span class="p">,</span><span class="p" data-group-id="1168755160-7">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1168755160-7">]</span><span class="p">,</span><span class="p" data-group-id="1168755160-8">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="1168755160-8">]</span><span class="p">,</span><span class="p" data-group-id="1168755160-9">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="1168755160-9">]</span><span class="p" data-group-id="1168755160-3">]</span></code></pre><h2 id="pythagorean-triplets" class="section-heading">
│ │ │ +removed:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">perms</span><span class="p" data-group-id="5568160203-1">(</span><span class="p" data-group-id="5568160203-2">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5568160203-2">]</span><span class="p" data-group-id="5568160203-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5568160203-3">[</span><span class="p" data-group-id="5568160203-4">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5568160203-4">]</span><span class="p">,</span><span class="p" data-group-id="5568160203-5">[</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="5568160203-5">]</span><span class="p">,</span><span class="p" data-group-id="5568160203-6">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">g</span><span class="p" data-group-id="5568160203-6">]</span><span class="p">,</span><span class="p" data-group-id="5568160203-7">[</span><span class="ss">u</span><span class="p">,</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5568160203-7">]</span><span class="p">,</span><span class="p" data-group-id="5568160203-8">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">u</span><span class="p" data-group-id="5568160203-8">]</span><span class="p">,</span><span class="p" data-group-id="5568160203-9">[</span><span class="ss">g</span><span class="p">,</span><span class="ss">u</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5568160203-9">]</span><span class="p" data-group-id="5568160203-3">]</span></code></pre><h2 id="pythagorean-triplets" class="section-heading">
│ │ │    <a href="#pythagorean-triplets" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Pythagorean Triplets</span>
│ │ │  </h2>
│ │ │  <p>Pythagorean triplets are sets of integers <code class="inline">{A,B,C}</code> such that
│ │ │  <code class="inline">A**2 + B**2 = C**2</code>.</p><p>The function <code class="inline">pyth(N)</code> generates a list of all integers <code class="inline">{A,B,C}</code> such that
│ │ │  <code class="inline">A**2 + B**2 = C**2</code> and where the sum of the sides is equal to, or less than,
│ │ │ -<code class="inline">N</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth</span><span class="p" data-group-id="0980041021-1">(</span><span class="n">N</span><span class="p" data-group-id="0980041021-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0980041021-2">[</span><span class="w"> </span><span class="p" data-group-id="0980041021-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="0980041021-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ -        </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0980041021-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0980041021-4">)</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0980041021-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0980041021-5">)</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0980041021-6">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0980041021-6">)</span><span class="p">,</span><span class="w">
│ │ │ +<code class="inline">N</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth</span><span class="p" data-group-id="0558675947-1">(</span><span class="n">N</span><span class="p" data-group-id="0558675947-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0558675947-2">[</span><span class="w"> </span><span class="p" data-group-id="0558675947-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="0558675947-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ +        </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0558675947-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0558675947-4">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0558675947-5">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0558675947-5">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="0558675947-6">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="0558675947-6">)</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">+</span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="n">A</span><span class="o">*</span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">*</span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">C</span><span class="o">*</span><span class="n">C</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0980041021-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="7686561680-1">(</span><span class="mi">3</span><span class="p" data-group-id="7686561680-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7686561680-2">[</span><span class="p" data-group-id="7686561680-2">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="7686561680-3">(</span><span class="mi">11</span><span class="p" data-group-id="7686561680-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7686561680-4">[</span><span class="p" data-group-id="7686561680-4">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="7686561680-5">(</span><span class="mi">12</span><span class="p" data-group-id="7686561680-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7686561680-6">[</span><span class="p" data-group-id="7686561680-7">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7686561680-7">}</span><span class="p">,</span><span class="p" data-group-id="7686561680-8">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7686561680-8">}</span><span class="p" data-group-id="7686561680-6">]</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="7686561680-9">(</span><span class="mi">50</span><span class="p" data-group-id="7686561680-9">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7686561680-10">[</span><span class="p" data-group-id="7686561680-11">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7686561680-11">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-12">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7686561680-12">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-13">{</span><span class="mi">5</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="7686561680-13">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-14">{</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="7686561680-14">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-15">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="7686561680-15">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-16">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="7686561680-16">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-17">{</span><span class="mi">9</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="7686561680-17">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-18">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="7686561680-18">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-19">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="7686561680-19">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-20">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="7686561680-20">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-21">{</span><span class="mi">15</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="7686561680-21">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7686561680-22">{</span><span class="mi">16</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="7686561680-22">}</span><span class="p" data-group-id="7686561680-10">]</span></code></pre><p>The following code reduces the search space and is more efficient:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth1</span><span class="p" data-group-id="1560355296-1">(</span><span class="n">N</span><span class="p" data-group-id="1560355296-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="p" data-group-id="1560355296-2">[</span><span class="p" data-group-id="1560355296-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="1560355296-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ -       </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="1560355296-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="1560355296-4">)</span><span class="p">,</span><span class="w">
│ │ │ -       </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="1560355296-5">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="1560355296-5">)</span><span class="p">,</span><span class="w">
│ │ │ -       </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="1560355296-6">(</span><span class="n">B</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="1560355296-6">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0558675947-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="9994381185-1">(</span><span class="mi">3</span><span class="p" data-group-id="9994381185-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9994381185-2">[</span><span class="p" data-group-id="9994381185-2">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="9994381185-3">(</span><span class="mi">11</span><span class="p" data-group-id="9994381185-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9994381185-4">[</span><span class="p" data-group-id="9994381185-4">]</span><span class="p">.</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="9994381185-5">(</span><span class="mi">12</span><span class="p" data-group-id="9994381185-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9994381185-6">[</span><span class="p" data-group-id="9994381185-7">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9994381185-7">}</span><span class="p">,</span><span class="p" data-group-id="9994381185-8">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9994381185-8">}</span><span class="p" data-group-id="9994381185-6">]</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">pyth</span><span class="p" data-group-id="9994381185-9">(</span><span class="mi">50</span><span class="p" data-group-id="9994381185-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9994381185-10">[</span><span class="p" data-group-id="9994381185-11">{</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9994381185-11">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-12">{</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="9994381185-12">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-13">{</span><span class="mi">5</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="9994381185-13">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-14">{</span><span class="mi">6</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="9994381185-14">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-15">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="9994381185-15">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-16">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="9994381185-16">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-17">{</span><span class="mi">9</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="9994381185-17">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-18">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="9994381185-18">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-19">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">15</span><span class="p" data-group-id="9994381185-19">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-20">{</span><span class="mi">12</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="9994381185-20">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-21">{</span><span class="mi">15</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">17</span><span class="p" data-group-id="9994381185-21">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="9994381185-22">{</span><span class="mi">16</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">20</span><span class="p" data-group-id="9994381185-22">}</span><span class="p" data-group-id="9994381185-10">]</span></code></pre><p>The following code reduces the search space and is more efficient:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pyth1</span><span class="p" data-group-id="9666973144-1">(</span><span class="n">N</span><span class="p" data-group-id="9666973144-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="p" data-group-id="9666973144-2">[</span><span class="p" data-group-id="9666973144-3">{</span><span class="n">A</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">C</span><span class="p" data-group-id="9666973144-3">}</span><span class="w"> </span><span class="p">||</span><span class="w">
│ │ │ +       </span><span class="n">A</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9666973144-4">(</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="9666973144-4">)</span><span class="p">,</span><span class="w">
│ │ │ +       </span><span class="n">B</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9666973144-5">(</span><span class="n">A</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="9666973144-5">)</span><span class="p">,</span><span class="w">
│ │ │ +       </span><span class="n">C</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">seq</span><span class="p" data-group-id="9666973144-6">(</span><span class="n">B</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">N</span><span class="p" data-group-id="9666973144-6">)</span><span class="p">,</span><span class="w">
│ │ │         </span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">+</span><span class="n">C</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w">
│ │ │ -       </span><span class="n">A</span><span class="o">*</span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">*</span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">C</span><span class="o">*</span><span class="n">C</span><span class="w"> </span><span class="p" data-group-id="1560355296-2">]</span><span class="p">.</span></code></pre><h2 id="simplifications-with-list-comprehensions" class="section-heading">
│ │ │ +       </span><span class="n">A</span><span class="o">*</span><span class="n">A</span><span class="o">+</span><span class="n">B</span><span class="o">*</span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">C</span><span class="o">*</span><span class="n">C</span><span class="w"> </span><span class="p" data-group-id="9666973144-2">]</span><span class="p">.</span></code></pre><h2 id="simplifications-with-list-comprehensions" class="section-heading">
│ │ │    <a href="#simplifications-with-list-comprehensions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Simplifications With List Comprehensions</span>
│ │ │  </h2>
│ │ │  <p>As an example, list comprehensions can be used to simplify some of the functions
│ │ │ -in <code class="inline">lists.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="7959103714-1">(</span><span class="n">L</span><span class="p" data-group-id="7959103714-1">)</span><span class="w">   </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="7959103714-2">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">L1</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="7959103714-2">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="7959103714-3">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7959103714-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7959103714-4">[</span><span class="n">Fun</span><span class="p" data-group-id="7959103714-5">(</span><span class="n">X</span><span class="p" data-group-id="7959103714-5">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7959103714-4">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">filter</span><span class="p" data-group-id="7959103714-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="7959103714-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7959103714-7">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="7959103714-8">(</span><span class="n">X</span><span class="p" data-group-id="7959103714-8">)</span><span class="p" data-group-id="7959103714-7">]</span><span class="p">.</span></code></pre><h2 id="variable-bindings-in-list-comprehensions" class="section-heading">
│ │ │ +in <code class="inline">lists.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="8790076708-1">(</span><span class="n">L</span><span class="p" data-group-id="8790076708-1">)</span><span class="w">   </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="8790076708-2">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">L1</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L1</span><span class="p" data-group-id="8790076708-2">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="8790076708-3">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8790076708-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8790076708-4">[</span><span class="n">Fun</span><span class="p" data-group-id="8790076708-5">(</span><span class="n">X</span><span class="p" data-group-id="8790076708-5">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8790076708-4">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">filter</span><span class="p" data-group-id="8790076708-6">(</span><span class="n">Pred</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8790076708-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8790076708-7">[</span><span class="n">X</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Pred</span><span class="p" data-group-id="8790076708-8">(</span><span class="n">X</span><span class="p" data-group-id="8790076708-8">)</span><span class="p" data-group-id="8790076708-7">]</span><span class="p">.</span></code></pre><h2 id="variable-bindings-in-list-comprehensions" class="section-heading">
│ │ │    <a href="#variable-bindings-in-list-comprehensions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Variable Bindings in List Comprehensions</span>
│ │ │  </h2>
│ │ │  <p>The scope rules for variables that occur in list comprehensions are as follows:</p><ul><li>All variables that occur in a generator pattern are assumed to be &quot;fresh&quot;
│ │ │  variables.</li><li>Any variables that are defined before the list comprehension, and that are
│ │ │  used in filters, have the values they had before the list comprehension.</li><li>Variables cannot be exported from a list comprehension.</li></ul><p>As an example of these rules, suppose you want to write the function <code class="inline">select</code>,
│ │ │  which selects certain elements from a list of tuples. Suppose you write
│ │ │  <code class="inline">select(X, L) -&gt; [Y || {X, Y} &lt;- L].</code> with the intention of extracting all
│ │ │  tuples from <code class="inline">L</code>, where the first item is <code class="inline">X</code>.</p><p>Compiling this gives the following diagnostic:</p><pre><code class="text">./FileName.erl:Line: Warning: variable 'X' shadowed in generate</code></pre><p>This diagnostic warns that the variable <code class="inline">X</code> in the pattern is not the same as
│ │ │ -the variable <code class="inline">X</code> that occurs in the function head.</p><p>Evaluating <code class="inline">select</code> gives the following result:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="5319126791-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="5319126791-2">[</span><span class="p" data-group-id="5319126791-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5319126791-3">}</span><span class="p">,</span><span class="p" data-group-id="5319126791-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5319126791-4">}</span><span class="p">,</span><span class="p" data-group-id="5319126791-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5319126791-5">}</span><span class="p">,</span><span class="p" data-group-id="5319126791-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="5319126791-6">}</span><span class="p" data-group-id="5319126791-2">]</span><span class="p" data-group-id="5319126791-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5319126791-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="5319126791-7">]</span></code></pre><p>This is not the wanted result. To achieve the desired effect, <code class="inline">select</code> must be
│ │ │ -written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">select</span><span class="p" data-group-id="4361690731-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4361690731-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="4361690731-2">[</span><span class="n">Y</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="4361690731-3">{</span><span class="n">X1</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4361690731-3">}</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">X1</span><span class="p" data-group-id="4361690731-2">]</span><span class="p">.</span></code></pre><p>The generator now contains unbound variables and the test has been moved into
│ │ │ -the filter.</p><p>This now works as expected:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="0683637536-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="0683637536-2">[</span><span class="p" data-group-id="0683637536-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0683637536-3">}</span><span class="p">,</span><span class="p" data-group-id="0683637536-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0683637536-4">}</span><span class="p">,</span><span class="p" data-group-id="0683637536-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0683637536-5">}</span><span class="p">,</span><span class="p" data-group-id="0683637536-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="0683637536-6">}</span><span class="p" data-group-id="0683637536-2">]</span><span class="p" data-group-id="0683637536-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0683637536-7">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="0683637536-7">]</span></code></pre><p>Also note that a variable in a generator pattern will shadow a variable with the
│ │ │ -same name bound in a previous generator pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="5225377097-1">[</span><span class="p" data-group-id="5225377097-2">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p" data-group-id="5225377097-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5225377097-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5225377097-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="o">=</span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="5225377097-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="5225377097-4">]</span><span class="p" data-group-id="5225377097-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5225377097-5">[</span><span class="p" data-group-id="5225377097-6">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="5225377097-6">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-7">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5225377097-7">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-8">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="5225377097-8">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="5225377097-9">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5225377097-10">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-11">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="5225377097-11">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-12">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="5225377097-12">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-13">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5225377097-13">}</span><span class="p">,</span><span class="p" data-group-id="5225377097-14">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="5225377097-14">}</span><span class="p" data-group-id="5225377097-5">]</span></code></pre><p>A consequence of the rules for importing variables into a list comprehensions is
│ │ │ +the variable <code class="inline">X</code> that occurs in the function head.</p><p>Evaluating <code class="inline">select</code> gives the following result:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="9519021706-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="9519021706-2">[</span><span class="p" data-group-id="9519021706-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9519021706-3">}</span><span class="p">,</span><span class="p" data-group-id="9519021706-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9519021706-4">}</span><span class="p">,</span><span class="p" data-group-id="9519021706-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9519021706-5">}</span><span class="p">,</span><span class="p" data-group-id="9519021706-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9519021706-6">}</span><span class="p" data-group-id="9519021706-2">]</span><span class="p" data-group-id="9519021706-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9519021706-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9519021706-7">]</span></code></pre><p>This is not the wanted result. To achieve the desired effect, <code class="inline">select</code> must be
│ │ │ +written as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">select</span><span class="p" data-group-id="8470548691-1">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="8470548691-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="p" data-group-id="8470548691-2">[</span><span class="n">Y</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="p" data-group-id="8470548691-3">{</span><span class="n">X1</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8470548691-3">}</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">X1</span><span class="p" data-group-id="8470548691-2">]</span><span class="p">.</span></code></pre><p>The generator now contains unbound variables and the test has been moved into
│ │ │ +the filter.</p><p>This now works as expected:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">select</span><span class="p" data-group-id="2804247995-1">(</span><span class="ss">b</span><span class="p">,</span><span class="p" data-group-id="2804247995-2">[</span><span class="p" data-group-id="2804247995-3">{</span><span class="ss">a</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2804247995-3">}</span><span class="p">,</span><span class="p" data-group-id="2804247995-4">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2804247995-4">}</span><span class="p">,</span><span class="p" data-group-id="2804247995-5">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2804247995-5">}</span><span class="p">,</span><span class="p" data-group-id="2804247995-6">{</span><span class="ss">b</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="2804247995-6">}</span><span class="p" data-group-id="2804247995-2">]</span><span class="p" data-group-id="2804247995-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2804247995-7">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="2804247995-7">]</span></code></pre><p>Also note that a variable in a generator pattern will shadow a variable with the
│ │ │ +same name bound in a previous generator pattern. For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="9548739096-1">[</span><span class="p" data-group-id="9548739096-2">{</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p" data-group-id="9548739096-2">}</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9548739096-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9548739096-3">]</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="o">=</span><span class="n">Y</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="p" data-group-id="9548739096-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="9548739096-4">]</span><span class="p" data-group-id="9548739096-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9548739096-5">[</span><span class="p" data-group-id="9548739096-6">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="9548739096-6">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-7">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9548739096-7">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-8">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="9548739096-8">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-9">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="9548739096-9">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-10">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9548739096-10">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-11">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="9548739096-11">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-12">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="9548739096-12">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-13">{</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="9548739096-13">}</span><span class="p">,</span><span class="p" data-group-id="9548739096-14">{</span><span class="ss">c</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="9548739096-14">}</span><span class="p" data-group-id="9548739096-5">]</span></code></pre><p>A consequence of the rules for importing variables into a list comprehensions is
│ │ │  that certain pattern matching operations must be moved into the filters and
│ │ │ -cannot be written directly in the generators.</p><p>To illustrate this, do <em>not</em> write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="6838364890-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6838364890-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +cannot be written directly in the generators.</p><p>To illustrate this, do <em>not</em> write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="1566825624-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1566825624-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6838364890-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6838364890-2">]</span><span class="w">
│ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Instead, write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="3493720080-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3493720080-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1566825624-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1566825624-2">]</span><span class="w">
│ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Instead, write as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="5722895457-1">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5722895457-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3493720080-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y1</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3493720080-2">]</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5722895457-2">[</span><span class="w"> </span><span class="n">Expression</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">PatternInvolving</span><span class="w"> </span><span class="n">Y1</span><span class="w">  </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">Expr</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Y1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="5722895457-2">]</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="funs.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/listhandling.html
│ │ │ @@ -120,105 +120,105 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Creating a List</span>
│ │ │  </h2>
│ │ │  <p>Lists can only be built starting from the end and attaching list elements at the
│ │ │  beginning. If you use the <code class="inline">++</code> operator as follows, a new list is created that
│ │ │  is a copy of the elements in <code class="inline">List1</code>, followed by <code class="inline">List2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">List1</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="n">List2</span></code></pre><p>Looking at how <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#append/2"><code class="inline">lists:append/2</code></a> or <code class="inline">++</code> would be implemented in plain Erlang,
│ │ │ -clearly the first list is copied:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="7452284780-1">(</span><span class="p" data-group-id="7452284780-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7452284780-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="7452284780-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7452284780-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">append</span><span class="p" data-group-id="7452284780-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="7452284780-4">)</span><span class="p" data-group-id="7452284780-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">append</span><span class="p" data-group-id="7452284780-5">(</span><span class="p" data-group-id="7452284780-6">[</span><span class="p" data-group-id="7452284780-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="7452284780-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +clearly the first list is copied:</p><pre><code class="makeup erlang" translate="no"><span class="nf">append</span><span class="p" data-group-id="1019385837-1">(</span><span class="p" data-group-id="1019385837-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1019385837-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="1019385837-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1019385837-3">[</span><span class="n">H</span><span class="p">|</span><span class="nf">append</span><span class="p" data-group-id="1019385837-4">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="1019385837-4">)</span><span class="p" data-group-id="1019385837-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">append</span><span class="p" data-group-id="1019385837-5">(</span><span class="p" data-group-id="1019385837-6">[</span><span class="p" data-group-id="1019385837-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Tail</span><span class="p" data-group-id="1019385837-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Tail</span><span class="p">.</span></code></pre><p>When recursing and building a list, it is important to ensure that you attach
│ │ │  the new elements to the beginning of the list. In this way, you will build <em>one</em>
│ │ │ -list, not hundreds or thousands of copies of the growing result list.</p><p>Let us first see how it is not to be done:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">bad_fib</span><span class="p" data-group-id="3457756843-1">(</span><span class="n">N</span><span class="p" data-group-id="3457756843-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">bad_fib</span><span class="p" data-group-id="3457756843-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3457756843-3">[</span><span class="p" data-group-id="3457756843-3">]</span><span class="p" data-group-id="3457756843-2">)</span><span class="p">.</span><span class="w">
│ │ │ +list, not hundreds or thousands of copies of the growing result list.</p><p>Let us first see how it is not to be done:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">bad_fib</span><span class="p" data-group-id="8151498814-1">(</span><span class="n">N</span><span class="p" data-group-id="8151498814-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">bad_fib</span><span class="p" data-group-id="8151498814-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8151498814-3">[</span><span class="p" data-group-id="8151498814-3">]</span><span class="p" data-group-id="8151498814-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">bad_fib</span><span class="p" data-group-id="3457756843-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="3457756843-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">bad_fib</span><span class="p" data-group-id="8151498814-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="8151498814-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Fibs</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">bad_fib</span><span class="p" data-group-id="3457756843-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="3457756843-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">bad_fib</span><span class="p" data-group-id="3457756843-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="3457756843-7">[</span><span class="n">Current</span><span class="p" data-group-id="3457756843-7">]</span><span class="p" data-group-id="3457756843-6">)</span><span class="p">.</span></code></pre><p>Here more than one list is built. In each iteration step a new list is created
│ │ │ +</span><span class="nf">bad_fib</span><span class="p" data-group-id="8151498814-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="8151498814-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">bad_fib</span><span class="p" data-group-id="8151498814-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="8151498814-7">[</span><span class="n">Current</span><span class="p" data-group-id="8151498814-7">]</span><span class="p" data-group-id="8151498814-6">)</span><span class="p">.</span></code></pre><p>Here more than one list is built. In each iteration step a new list is created
│ │ │  that is one element longer than the new previous list.</p><p>To avoid copying the result in each iteration, build the list in reverse order
│ │ │ -and reverse the list when you are done:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="1532208228-1">(</span><span class="n">N</span><span class="p" data-group-id="1532208228-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="1532208228-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1532208228-3">[</span><span class="p" data-group-id="1532208228-3">]</span><span class="p" data-group-id="1532208228-2">)</span><span class="p">.</span><span class="w">
│ │ │ +and reverse the list when you are done:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="9375384406-1">(</span><span class="n">N</span><span class="p" data-group-id="9375384406-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="9375384406-2">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9375384406-3">[</span><span class="p" data-group-id="9375384406-3">]</span><span class="p" data-group-id="9375384406-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="1532208228-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="1532208228-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="1532208228-5">(</span><span class="n">Fibs</span><span class="p" data-group-id="1532208228-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="1532208228-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="1532208228-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="1532208228-7">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1532208228-8">[</span><span class="n">Current</span><span class="p">|</span><span class="n">Fibs</span><span class="p" data-group-id="1532208228-8">]</span><span class="p" data-group-id="1532208228-7">)</span><span class="p">.</span></code></pre><h2 id="list-comprehensions" class="section-heading">
│ │ │ +</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="9375384406-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="9375384406-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9375384406-5">(</span><span class="n">Fibs</span><span class="p" data-group-id="9375384406-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="9375384406-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Fibs</span><span class="p" data-group-id="9375384406-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">tail_recursive_fib</span><span class="p" data-group-id="9375384406-7">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">Next</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9375384406-8">[</span><span class="n">Current</span><span class="p">|</span><span class="n">Fibs</span><span class="p" data-group-id="9375384406-8">]</span><span class="p" data-group-id="9375384406-7">)</span><span class="p">.</span></code></pre><h2 id="list-comprehensions" class="section-heading">
│ │ │    <a href="#list-comprehensions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">List Comprehensions</span>
│ │ │  </h2>
│ │ │ -<p>A list comprehension:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2764433075-1">[</span><span class="n">Expr</span><span class="p" data-group-id="2764433075-2">(</span><span class="n">E</span><span class="p" data-group-id="2764433075-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2764433075-1">]</span></code></pre><p>is basically translated to a local function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="3917407386-1">(</span><span class="p" data-group-id="3917407386-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="3917407386-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="3917407386-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3917407386-3">[</span><span class="n">Expr</span><span class="p" data-group-id="3917407386-4">(</span><span class="n">E</span><span class="p" data-group-id="3917407386-4">)</span><span class="p">|</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="3917407386-5">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="3917407386-5">)</span><span class="p" data-group-id="3917407386-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="3917407386-6">(</span><span class="p" data-group-id="3917407386-7">[</span><span class="p" data-group-id="3917407386-7">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="3917407386-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3917407386-8">[</span><span class="p" data-group-id="3917407386-8">]</span><span class="p">.</span></code></pre><p>If the result of the list comprehension will <em>obviously</em> not be used, a list
│ │ │ -will not be constructed. For example, in this code:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7135854056-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="7135854056-2">(</span><span class="n">E</span><span class="p" data-group-id="7135854056-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="7135854056-1">]</span><span class="p">,</span><span class="w">
│ │ │ +<p>A list comprehension:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8273986301-1">[</span><span class="n">Expr</span><span class="p" data-group-id="8273986301-2">(</span><span class="n">E</span><span class="p" data-group-id="8273986301-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="8273986301-1">]</span></code></pre><p>is basically translated to a local function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="4577655304-1">(</span><span class="p" data-group-id="4577655304-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="4577655304-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="4577655304-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4577655304-3">[</span><span class="n">Expr</span><span class="p" data-group-id="4577655304-4">(</span><span class="n">E</span><span class="p" data-group-id="4577655304-4">)</span><span class="p">|</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="4577655304-5">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="4577655304-5">)</span><span class="p" data-group-id="4577655304-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="4577655304-6">(</span><span class="p" data-group-id="4577655304-7">[</span><span class="p" data-group-id="4577655304-7">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="4577655304-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4577655304-8">[</span><span class="p" data-group-id="4577655304-8">]</span><span class="p">.</span></code></pre><p>If the result of the list comprehension will <em>obviously</em> not be used, a list
│ │ │ +will not be constructed. For example, in this code:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1153303641-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="1153303641-2">(</span><span class="n">E</span><span class="p" data-group-id="1153303641-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="1153303641-1">]</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>or in this code:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="n">Var</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4249436959-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="4249436959-2">(</span><span class="n">E</span><span class="p" data-group-id="4249436959-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="4249436959-1">]</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1105587854-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="1105587854-2">(</span><span class="n">E</span><span class="p" data-group-id="1105587854-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="1105587854-1">]</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">some_function</span><span class="p" data-group-id="4249436959-3">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4249436959-3">)</span><span class="p">,</span></code></pre><p>the value is not assigned to a variable, not passed to another function, and not
│ │ │ +</span><span class="nf">some_function</span><span class="p" data-group-id="1105587854-3">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1105587854-3">)</span><span class="p">,</span></code></pre><p>the value is not assigned to a variable, not passed to another function, and not
│ │ │  returned. This means that there is no need to construct a list and the compiler
│ │ │ -will simplify the code for the list comprehension to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="1632935320-1">(</span><span class="p" data-group-id="1632935320-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="1632935320-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="1632935320-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Expr</span><span class="p" data-group-id="1632935320-3">(</span><span class="n">E</span><span class="p" data-group-id="1632935320-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="1632935320-4">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="1632935320-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="1632935320-5">(</span><span class="p" data-group-id="1632935320-6">[</span><span class="p" data-group-id="1632935320-6">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="1632935320-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1632935320-7">[</span><span class="p" data-group-id="1632935320-7">]</span><span class="p">.</span></code></pre><p>The compiler also understands that assigning to <code class="inline">_</code> means that the value will
│ │ │ -not be used. Therefore, the code in the following example will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3252222231-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="3252222231-2">(</span><span class="n">E</span><span class="p" data-group-id="3252222231-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="3252222231-1">]</span><span class="p">,</span><span class="w">
│ │ │ +will simplify the code for the list comprehension to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="5520301891-1">(</span><span class="p" data-group-id="5520301891-2">[</span><span class="n">E</span><span class="p">|</span><span class="n">Tail</span><span class="p" data-group-id="5520301891-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="5520301891-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Expr</span><span class="p" data-group-id="5520301891-3">(</span><span class="n">E</span><span class="p" data-group-id="5520301891-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="5520301891-4">(</span><span class="n">Tail</span><span class="p">,</span><span class="w"> </span><span class="n">Expr</span><span class="p" data-group-id="5520301891-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">&#39;lc^0&#39;</span><span class="p" data-group-id="5520301891-5">(</span><span class="p" data-group-id="5520301891-6">[</span><span class="p" data-group-id="5520301891-6">]</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Expr</span><span class="p" data-group-id="5520301891-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5520301891-7">[</span><span class="p" data-group-id="5520301891-7">]</span><span class="p">.</span></code></pre><p>The compiler also understands that assigning to <code class="inline">_</code> means that the value will
│ │ │ +not be used. Therefore, the code in the following example will also be optimized:</p><pre><code class="makeup erlang" translate="no"><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6346150978-1">[</span><span class="nc">io</span><span class="p">:</span><span class="nf">put_chars</span><span class="p" data-group-id="6346150978-2">(</span><span class="n">E</span><span class="p" data-group-id="6346150978-2">)</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">E</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="6346150978-1">]</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="p">.</span></code></pre><h2 id="deep-and-flat-lists" class="section-heading">
│ │ │    <a href="#deep-and-flat-lists" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Deep and Flat Lists</span>
│ │ │  </h2>
│ │ │  <p><a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#flatten/1"><code class="inline">lists:flatten/1</code></a> builds an entirely new list. It is therefore expensive, and
│ │ │  even <em>more</em> expensive than the <code class="inline">++</code> operator (which copies its left argument,
│ │ │  but not its right argument).</p><p>In the following situations it is unnecessary to call <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#flatten/1"><code class="inline">lists:flatten/1</code></a>:</p><ul><li>When sending data to a port. Ports understand deep lists so there is no reason
│ │ │  to flatten the list before sending it to the port.</li><li>When calling BIFs that accept deep lists, such as
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#list_to_binary/1"><code class="inline">list_to_binary/1</code></a> or
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#iolist_to_binary/1"><code class="inline">iolist_to_binary/1</code></a>.</li><li>When you know that your list is only one level deep. Use <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#append/1"><code class="inline">lists:append/1</code></a>
│ │ │ -instead.</li></ul><p><em>Examples:</em></p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="0300577127-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">DeepList</span><span class="p" data-group-id="0300577127-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="5519313542-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="5519313542-2">(</span><span class="n">DeepList</span><span class="p" data-group-id="5519313542-2">)</span><span class="p" data-group-id="5519313542-1">)</span></code></pre><p>A common way to send a zero-terminated string to a port is the following:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">String</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9174725518-1">[</span><span class="mi">0</span><span class="p" data-group-id="9174725518-1">]</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">port_command</span><span class="p" data-group-id="9174725518-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="9174725518-2">)</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7413628999-1">[</span><span class="n">String</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7413628999-1">]</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">port_command</span><span class="p" data-group-id="7413628999-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="7413628999-2">)</span></code></pre><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">append</span><span class="p" data-group-id="3272632868-1">(</span><span class="p" data-group-id="3272632868-2">[</span><span class="p" data-group-id="3272632868-3">[</span><span class="mi">1</span><span class="p" data-group-id="3272632868-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3272632868-4">[</span><span class="mi">2</span><span class="p" data-group-id="3272632868-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3272632868-5">[</span><span class="mi">3</span><span class="p" data-group-id="3272632868-5">]</span><span class="p" data-group-id="3272632868-2">]</span><span class="p" data-group-id="3272632868-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3272632868-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3272632868-6">]</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="7110292609-1">(</span><span class="p" data-group-id="7110292609-2">[</span><span class="p" data-group-id="7110292609-3">[</span><span class="mi">1</span><span class="p" data-group-id="7110292609-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7110292609-4">[</span><span class="mi">2</span><span class="p" data-group-id="7110292609-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7110292609-5">[</span><span class="mi">3</span><span class="p" data-group-id="7110292609-5">]</span><span class="p" data-group-id="7110292609-2">]</span><span class="p" data-group-id="7110292609-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7110292609-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7110292609-6">]</span></code></pre><h2 id="recursive-list-functions" class="section-heading">
│ │ │ +instead.</li></ul><p><em>Examples:</em></p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="8034989597-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">DeepList</span><span class="p" data-group-id="8034989597-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">port_command</span><span class="p" data-group-id="5769520315-1">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="5769520315-2">(</span><span class="n">DeepList</span><span class="p" data-group-id="5769520315-2">)</span><span class="p" data-group-id="5769520315-1">)</span></code></pre><p>A common way to send a zero-terminated string to a port is the following:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">String</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="0537995468-1">[</span><span class="mi">0</span><span class="p" data-group-id="0537995468-1">]</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">port_command</span><span class="p" data-group-id="0537995468-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="0537995468-2">)</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TerminatedStr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4712819849-1">[</span><span class="n">String</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4712819849-1">]</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">port_command</span><span class="p" data-group-id="4712819849-2">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">TerminatedStr</span><span class="p" data-group-id="4712819849-2">)</span></code></pre><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">append</span><span class="p" data-group-id="7129086470-1">(</span><span class="p" data-group-id="7129086470-2">[</span><span class="p" data-group-id="7129086470-3">[</span><span class="mi">1</span><span class="p" data-group-id="7129086470-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7129086470-4">[</span><span class="mi">2</span><span class="p" data-group-id="7129086470-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7129086470-5">[</span><span class="mi">3</span><span class="p" data-group-id="7129086470-5">]</span><span class="p" data-group-id="7129086470-2">]</span><span class="p" data-group-id="7129086470-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7129086470-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7129086470-6">]</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">flatten</span><span class="p" data-group-id="8874128886-1">(</span><span class="p" data-group-id="8874128886-2">[</span><span class="p" data-group-id="8874128886-3">[</span><span class="mi">1</span><span class="p" data-group-id="8874128886-3">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8874128886-4">[</span><span class="mi">2</span><span class="p" data-group-id="8874128886-4">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8874128886-5">[</span><span class="mi">3</span><span class="p" data-group-id="8874128886-5">]</span><span class="p" data-group-id="8874128886-2">]</span><span class="p" data-group-id="8874128886-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8874128886-6">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8874128886-6">]</span></code></pre><h2 id="recursive-list-functions" class="section-heading">
│ │ │    <a href="#recursive-list-functions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Recursive List Functions</span>
│ │ │  </h2>
│ │ │  <p>There are two basic ways to write a function that traverses a list and
│ │ │  produces a new list.</p><p>The first way is writing a <em>body-recursive</em> function:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Add 42 to each integer in the list.</span><span class="w">
│ │ │ -</span><span class="nf">add_42_body</span><span class="p" data-group-id="2978681241-1">(</span><span class="p" data-group-id="2978681241-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2978681241-2">]</span><span class="p" data-group-id="2978681241-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2978681241-3">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">add_42_body</span><span class="p" data-group-id="2978681241-4">(</span><span class="n">T</span><span class="p" data-group-id="2978681241-4">)</span><span class="p" data-group-id="2978681241-3">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">add_42_body</span><span class="p" data-group-id="2978681241-5">(</span><span class="p" data-group-id="2978681241-6">[</span><span class="p" data-group-id="2978681241-6">]</span><span class="p" data-group-id="2978681241-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2978681241-7">[</span><span class="p" data-group-id="2978681241-7">]</span><span class="p">.</span></code></pre><p>The second way is writing a <em>tail-recursive</em> function:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Add 42 to each integer in the list.</span><span class="w">
│ │ │ -</span><span class="nf">add_42_tail</span><span class="p" data-group-id="8352670239-1">(</span><span class="n">List</span><span class="p" data-group-id="8352670239-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="8352670239-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8352670239-3">[</span><span class="p" data-group-id="8352670239-3">]</span><span class="p" data-group-id="8352670239-2">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">add_42_tail</span><span class="p" data-group-id="8352670239-4">(</span><span class="p" data-group-id="8352670239-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="8352670239-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8352670239-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="8352670239-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8352670239-7">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8352670239-7">]</span><span class="p" data-group-id="8352670239-6">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">add_42_tail</span><span class="p" data-group-id="8352670239-8">(</span><span class="p" data-group-id="8352670239-9">[</span><span class="p" data-group-id="8352670239-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="8352670239-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="8352670239-10">(</span><span class="n">Acc</span><span class="p" data-group-id="8352670239-10">)</span><span class="p">.</span></code></pre><p>In early version of Erlang the tail-recursive function would typically
│ │ │ +</span><span class="nf">add_42_body</span><span class="p" data-group-id="6954230129-1">(</span><span class="p" data-group-id="6954230129-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="6954230129-2">]</span><span class="p" data-group-id="6954230129-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6954230129-3">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">add_42_body</span><span class="p" data-group-id="6954230129-4">(</span><span class="n">T</span><span class="p" data-group-id="6954230129-4">)</span><span class="p" data-group-id="6954230129-3">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">add_42_body</span><span class="p" data-group-id="6954230129-5">(</span><span class="p" data-group-id="6954230129-6">[</span><span class="p" data-group-id="6954230129-6">]</span><span class="p" data-group-id="6954230129-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6954230129-7">[</span><span class="p" data-group-id="6954230129-7">]</span><span class="p">.</span></code></pre><p>The second way is writing a <em>tail-recursive</em> function:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% Add 42 to each integer in the list.</span><span class="w">
│ │ │ +</span><span class="nf">add_42_tail</span><span class="p" data-group-id="5885292364-1">(</span><span class="n">List</span><span class="p" data-group-id="5885292364-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="5885292364-2">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5885292364-3">[</span><span class="p" data-group-id="5885292364-3">]</span><span class="p" data-group-id="5885292364-2">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">add_42_tail</span><span class="p" data-group-id="5885292364-4">(</span><span class="p" data-group-id="5885292364-5">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="5885292364-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="5885292364-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">add_42_tail</span><span class="p" data-group-id="5885292364-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5885292364-7">[</span><span class="n">H</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="5885292364-7">]</span><span class="p" data-group-id="5885292364-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">add_42_tail</span><span class="p" data-group-id="5885292364-8">(</span><span class="p" data-group-id="5885292364-9">[</span><span class="p" data-group-id="5885292364-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="5885292364-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="5885292364-10">(</span><span class="n">Acc</span><span class="p" data-group-id="5885292364-10">)</span><span class="p">.</span></code></pre><p>In early version of Erlang the tail-recursive function would typically
│ │ │  be more efficient. In modern versions of Erlang, there is usually not
│ │ │  much difference in performance between a body-recursive list function and
│ │ │  tail-recursive function that reverses the list at the end. Therefore,
│ │ │  concentrate on writing beautiful code and forget about the performance
│ │ │  of your list functions. In the time-critical parts of your code,
│ │ │  <em>measure</em> before rewriting your code.</p><p>For a thorough discussion about tail and body recursion, see
│ │ │  <a href="http://ferd.ca/erlang-s-tail-recursion-is-not-a-silver-bullet.html">Erlang's Tail Recursion is Not a Silver Bullet</a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>This section is about list functions that <em>construct</em> lists. A tail-recursive
│ │ │  function that does not construct a list runs in constant space, while the
│ │ │  corresponding body-recursive function uses stack space proportional to the
│ │ │  length of the list.</p></section><p>For example, a function that sums a list of integers, is <em>not</em> to be written as
│ │ │ -follows:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">recursive_sum</span><span class="p" data-group-id="1605542746-1">(</span><span class="p" data-group-id="1605542746-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="1605542746-2">]</span><span class="p" data-group-id="1605542746-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">H</span><span class="o">+</span><span class="nf">recursive_sum</span><span class="p" data-group-id="1605542746-3">(</span><span class="n">T</span><span class="p" data-group-id="1605542746-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">recursive_sum</span><span class="p" data-group-id="1605542746-4">(</span><span class="p" data-group-id="1605542746-5">[</span><span class="p" data-group-id="1605542746-5">]</span><span class="p" data-group-id="1605542746-4">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p">.</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">sum</span><span class="p" data-group-id="7364081425-1">(</span><span class="n">L</span><span class="p" data-group-id="7364081425-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="7364081425-2">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="7364081425-2">)</span><span class="p">.</span><span class="w">
│ │ │ +follows:</p><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">recursive_sum</span><span class="p" data-group-id="2596028025-1">(</span><span class="p" data-group-id="2596028025-2">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="2596028025-2">]</span><span class="p" data-group-id="2596028025-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">H</span><span class="o">+</span><span class="nf">recursive_sum</span><span class="p" data-group-id="2596028025-3">(</span><span class="n">T</span><span class="p" data-group-id="2596028025-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">recursive_sum</span><span class="p" data-group-id="2596028025-4">(</span><span class="p" data-group-id="2596028025-5">[</span><span class="p" data-group-id="2596028025-5">]</span><span class="p" data-group-id="2596028025-4">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p">.</span></code></pre><p>Instead:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nf">sum</span><span class="p" data-group-id="0430521299-1">(</span><span class="n">L</span><span class="p" data-group-id="0430521299-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="0430521299-2">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="0430521299-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">sum</span><span class="p" data-group-id="7364081425-3">(</span><span class="p" data-group-id="7364081425-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="7364081425-4">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="7364081425-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="7364081425-5">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">H</span><span class="p" data-group-id="7364081425-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">sum</span><span class="p" data-group-id="7364081425-6">(</span><span class="p" data-group-id="7364081425-7">[</span><span class="p" data-group-id="7364081425-7">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="7364081425-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Sum</span><span class="p">.</span></code></pre>
│ │ │ +</span><span class="nf">sum</span><span class="p" data-group-id="0430521299-3">(</span><span class="p" data-group-id="0430521299-4">[</span><span class="n">H</span><span class="p">|</span><span class="n">T</span><span class="p" data-group-id="0430521299-4">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="0430521299-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">sum</span><span class="p" data-group-id="0430521299-5">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">H</span><span class="p" data-group-id="0430521299-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">sum</span><span class="p" data-group-id="0430521299-6">(</span><span class="p" data-group-id="0430521299-7">[</span><span class="p" data-group-id="0430521299-7">]</span><span class="p">,</span><span class="w"> </span><span class="n">Sum</span><span class="p" data-group-id="0430521299-6">)</span><span class="w">    </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Sum</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="maps.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/macros.html
│ │ │ @@ -117,56 +117,56 @@
│ │ │  
│ │ │  <h2 id="file-inclusion" class="section-heading">
│ │ │    <a href="#file-inclusion" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">File Inclusion</span>
│ │ │  </h2>
│ │ │ -<p>A file can be included as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8373228316-1">(</span><span class="n">File</span><span class="p" data-group-id="8373228316-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="8373228316-2">(</span><span class="n">File</span><span class="p" data-group-id="8373228316-2">)</span><span class="p">.</span></code></pre><p><code class="inline">File</code>, a string, is to point out a file. The contents of this file are included
│ │ │ +<p>A file can be included as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="7871822158-1">(</span><span class="n">File</span><span class="p" data-group-id="7871822158-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="7871822158-2">(</span><span class="n">File</span><span class="p" data-group-id="7871822158-2">)</span><span class="p">.</span></code></pre><p><code class="inline">File</code>, a string, is to point out a file. The contents of this file are included
│ │ │  as is, at the position of the directive.</p><p>Include files are typically used for record and macro definitions that are
│ │ │  shared by several modules. It is recommended to use the file name extension
│ │ │  <code class="inline">.hrl</code> for include files.</p><p><code class="inline">File</code> can start with a path component <code class="inline">$VAR</code>, for some string <code class="inline">VAR</code>. If that is
│ │ │  the case, the value of the environment variable <code class="inline">VAR</code> as returned by
│ │ │  <code class="inline">os:getenv(VAR)</code> is substituted for <code class="inline">$VAR</code>. If <code class="inline">os:getenv(VAR)</code> returns <code class="inline">false</code>,
│ │ │  <code class="inline">$VAR</code> is left as is.</p><p>If the filename <code class="inline">File</code> is absolute (possibly after variable substitution), the
│ │ │  include file with that name is included. Otherwise, the specified file is
│ │ │  searched for in the following directories, and in this order:</p><ol><li>The current working directory</li><li>The directory where the module is being compiled</li><li>The directories given by the <code class="inline">include</code> option</li></ol><p>For details, see <a href="../../erts-15.2.7.3/doc/html/erlc_cmd.html">erlc</a> in ERTS and
│ │ │ -<a href="../../lib/compiler-8.6.1.2/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0579314116-1">(</span><span class="s">&quot;my_records.hrl&quot;</span><span class="p" data-group-id="0579314116-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0579314116-2">(</span><span class="s">&quot;incdir/my_records.hrl&quot;</span><span class="p" data-group-id="0579314116-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0579314116-3">(</span><span class="s">&quot;/home/user/proj/my_records.hrl&quot;</span><span class="p" data-group-id="0579314116-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="0579314116-4">(</span><span class="s">&quot;$PROJ_ROOT/my_records.hrl&quot;</span><span class="p" data-group-id="0579314116-4">)</span><span class="p">.</span></code></pre><p><code class="inline">include_lib</code> is similar to <code class="inline">include</code>, but is not to point out an absolute file.
│ │ │ +<a href="../../lib/compiler-8.6.1.2/doc/html/compile.html"><code class="inline">compile</code></a> in Compiler.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="6239130345-1">(</span><span class="s">&quot;my_records.hrl&quot;</span><span class="p" data-group-id="6239130345-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="6239130345-2">(</span><span class="s">&quot;incdir/my_records.hrl&quot;</span><span class="p" data-group-id="6239130345-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="6239130345-3">(</span><span class="s">&quot;/home/user/proj/my_records.hrl&quot;</span><span class="p" data-group-id="6239130345-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="6239130345-4">(</span><span class="s">&quot;$PROJ_ROOT/my_records.hrl&quot;</span><span class="p" data-group-id="6239130345-4">)</span><span class="p">.</span></code></pre><p><code class="inline">include_lib</code> is similar to <code class="inline">include</code>, but is not to point out an absolute file.
│ │ │  Instead, the first path component (possibly after variable substitution) is
│ │ │ -assumed to be the name of an application.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="7338601033-1">(</span><span class="s">&quot;kernel/include/file.hrl&quot;</span><span class="p" data-group-id="7338601033-1">)</span><span class="p">.</span></code></pre><p>The code server uses <code class="inline">code:lib_dir(kernel)</code> to find the directory of the current
│ │ │ +assumed to be the name of an application.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="7544178882-1">(</span><span class="s">&quot;kernel/include/file.hrl&quot;</span><span class="p" data-group-id="7544178882-1">)</span><span class="p">.</span></code></pre><p>The code server uses <code class="inline">code:lib_dir(kernel)</code> to find the directory of the current
│ │ │  (latest) version of Kernel, and then the subdirectory <code class="inline">include</code> is searched for
│ │ │  the file <code class="inline">file.hrl</code>.</p><h2 id="defining-and-using-macros" class="section-heading">
│ │ │    <a href="#defining-and-using-macros" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Defining and Using Macros</span>
│ │ │  </h2>
│ │ │ -<p>A macro is defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0031276597-1">(</span><span class="n">Const</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="0031276597-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0031276597-2">(</span><span class="n">Func</span><span class="p" data-group-id="0031276597-3">(</span><span class="n">Var1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">VarN</span><span class="p" data-group-id="0031276597-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="0031276597-2">)</span><span class="p">.</span></code></pre><p>A macro definition can be placed anywhere among the attributes and function
│ │ │ +<p>A macro is defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6463161173-1">(</span><span class="n">Const</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="6463161173-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6463161173-2">(</span><span class="n">Func</span><span class="p" data-group-id="6463161173-3">(</span><span class="n">Var1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">VarN</span><span class="p" data-group-id="6463161173-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="6463161173-2">)</span><span class="p">.</span></code></pre><p>A macro definition can be placed anywhere among the attributes and function
│ │ │  declarations of a module, but the definition must come before any usage of the
│ │ │  macro.</p><p>If a macro is used in several modules, it is recommended that the macro
│ │ │  definition is placed in an include file.</p><p>A macro is used as follows:</p><pre><code class="text">?Const
│ │ │  ?Func(Arg1,...,ArgN)</code></pre><p>Macros are expanded during compilation. A simple macro <code class="inline">?Const</code> is replaced with
│ │ │ -<code class="inline">Replacement</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9009286061-1">(</span><span class="n">TIMEOUT</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="9009286061-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">Replacement</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7219611589-1">(</span><span class="n">TIMEOUT</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="7219611589-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">call</span><span class="p" data-group-id="9009286061-2">(</span><span class="n">Request</span><span class="p" data-group-id="9009286061-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="9009286061-3">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">TIMEOUT</span><span class="p" data-group-id="9009286061-3">)</span><span class="p">.</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">call</span><span class="p" data-group-id="3300368777-1">(</span><span class="n">Request</span><span class="p" data-group-id="3300368777-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="3300368777-2">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="3300368777-2">)</span><span class="p">.</span></code></pre><p>A macro <code class="inline">?Func(Arg1,...,ArgN)</code> is replaced with <code class="inline">Replacement</code>, where all
│ │ │ +</span><span class="nf">call</span><span class="p" data-group-id="7219611589-2">(</span><span class="n">Request</span><span class="p" data-group-id="7219611589-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="7219611589-3">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">TIMEOUT</span><span class="p" data-group-id="7219611589-3">)</span><span class="p">.</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">call</span><span class="p" data-group-id="8948589452-1">(</span><span class="n">Request</span><span class="p" data-group-id="8948589452-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="8948589452-2">(</span><span class="ss">refserver</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="mi">200</span><span class="p" data-group-id="8948589452-2">)</span><span class="p">.</span></code></pre><p>A macro <code class="inline">?Func(Arg1,...,ArgN)</code> is replaced with <code class="inline">Replacement</code>, where all
│ │ │  occurrences of a variable <code class="inline">Var</code> from the macro definition are replaced with the
│ │ │ -corresponding argument <code class="inline">Arg</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1614909021-1">(</span><span class="n">MACRO1</span><span class="p" data-group-id="1614909021-2">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1614909021-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1614909021-3">{</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1614909021-3">}</span><span class="p" data-group-id="1614909021-1">)</span><span class="p">.</span><span class="w">
│ │ │ +corresponding argument <code class="inline">Arg</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5646635253-1">(</span><span class="n">MACRO1</span><span class="p" data-group-id="5646635253-2">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5646635253-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5646635253-3">{</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="5646635253-3">}</span><span class="p" data-group-id="5646635253-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="1614909021-4">(</span><span class="n">X</span><span class="p" data-group-id="1614909021-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="1614909021-5">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="1614909021-5">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="1614909021-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="mi">123</span><span class="p" data-group-id="1614909021-6">)</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="3938422329-1">(</span><span class="n">X</span><span class="p" data-group-id="3938422329-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3938422329-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="3938422329-2">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3938422329-3">{</span><span class="ss">a</span><span class="p">,</span><span class="n">X</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">123</span><span class="p" data-group-id="3938422329-3">}</span><span class="p">.</span></code></pre><p>It is good programming practice, but not mandatory, to ensure that a macro
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="5646635253-4">(</span><span class="n">X</span><span class="p" data-group-id="5646635253-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="5646635253-5">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p" data-group-id="5646635253-5">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="o">?</span><span class="n">MACRO1</span><span class="p" data-group-id="5646635253-6">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="mi">123</span><span class="p" data-group-id="5646635253-6">)</span></code></pre><p>This is expanded to:</p><pre><code class="makeup erlang" translate="no"><span class="nf">bar</span><span class="p" data-group-id="6027683554-1">(</span><span class="n">X</span><span class="p" data-group-id="6027683554-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6027683554-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6027683554-2">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6027683554-3">{</span><span class="ss">a</span><span class="p">,</span><span class="n">X</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="mi">123</span><span class="p" data-group-id="6027683554-3">}</span><span class="p">.</span></code></pre><p>It is good programming practice, but not mandatory, to ensure that a macro
│ │ │  definition is a valid Erlang syntactic form.</p><p>To view the result of macro expansion, a module can be compiled with the <code class="inline">'P'</code>
│ │ │  option. <code class="inline">compile:file(File, ['P'])</code>. This produces a listing of the parsed code
│ │ │  after preprocessing and parse transforms, in the file <code class="inline">File.P</code>.</p><h2 id="predefined-macros" class="section-heading">
│ │ │    <a href="#predefined-macros" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Predefined Macros</span>
│ │ │ @@ -185,29 +185,29 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Macros Overloading</span>
│ │ │  </h2>
│ │ │  <p>It is possible to overload macros, except for predefined macros. An overloaded
│ │ │  macro has more than one definition, each with a different number of arguments.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Support for overloading of macros was added in Erlang 5.7.5/OTP R13B04.</p></section><p>A macro <code class="inline">?Func(Arg1,...,ArgN)</code> with a (possibly empty) list of arguments results
│ │ │  in an error message if there is at least one definition of <code class="inline">Func</code> with
│ │ │ -arguments, but none with N arguments.</p><p>Assuming these definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7943957343-1">(</span><span class="n">F0</span><span class="p" data-group-id="7943957343-2">(</span><span class="p" data-group-id="7943957343-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="7943957343-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7943957343-3">(</span><span class="n">F1</span><span class="p" data-group-id="7943957343-4">(</span><span class="n">A</span><span class="p" data-group-id="7943957343-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="7943957343-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7943957343-5">(</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="nc">m</span><span class="p">:</span><span class="ss">f</span><span class="p" data-group-id="7943957343-5">)</span><span class="p">.</span></code></pre><p>the following does not work:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f0</span><span class="p" data-group-id="3521763082-1">(</span><span class="p" data-group-id="3521763082-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +arguments, but none with N arguments.</p><p>Assuming these definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2871717104-1">(</span><span class="n">F0</span><span class="p" data-group-id="2871717104-2">(</span><span class="p" data-group-id="2871717104-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="2871717104-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2871717104-3">(</span><span class="n">F1</span><span class="p" data-group-id="2871717104-4">(</span><span class="n">A</span><span class="p" data-group-id="2871717104-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="2871717104-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2871717104-5">(</span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="nc">m</span><span class="p">:</span><span class="ss">f</span><span class="p" data-group-id="2871717104-5">)</span><span class="p">.</span></code></pre><p>the following does not work:</p><pre><code class="makeup erlang" translate="no"><span class="nf">f0</span><span class="p" data-group-id="2726483271-1">(</span><span class="p" data-group-id="2726483271-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="o">?</span><span class="n">F0</span><span class="p">.</span><span class="w"> </span><span class="c1">% No, an empty list of arguments expected.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">f1</span><span class="p" data-group-id="3521763082-2">(</span><span class="n">A</span><span class="p" data-group-id="3521763082-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="o">?</span><span class="n">F1</span><span class="p" data-group-id="3521763082-3">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="3521763082-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% No, exactly one argument expected.</span></code></pre><p>On the other hand,</p><pre><code class="text">f() -&gt;
│ │ │ -    ?C().</code></pre><p>is expanded to</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="4857885483-1">(</span><span class="p" data-group-id="4857885483-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">m</span><span class="p">:</span><span class="nf">f</span><span class="p" data-group-id="4857885483-2">(</span><span class="p" data-group-id="4857885483-2">)</span><span class="p">.</span></code></pre><h2 id="removing-a-macro-definition" class="section-heading">
│ │ │ +</span><span class="nf">f1</span><span class="p" data-group-id="2726483271-2">(</span><span class="n">A</span><span class="p" data-group-id="2726483271-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="o">?</span><span class="n">F1</span><span class="p" data-group-id="2726483271-3">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="2726483271-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% No, exactly one argument expected.</span></code></pre><p>On the other hand,</p><pre><code class="text">f() -&gt;
│ │ │ +    ?C().</code></pre><p>is expanded to</p><pre><code class="makeup erlang" translate="no"><span class="nf">f</span><span class="p" data-group-id="4687342510-1">(</span><span class="p" data-group-id="4687342510-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">m</span><span class="p">:</span><span class="nf">f</span><span class="p" data-group-id="4687342510-2">(</span><span class="p" data-group-id="4687342510-2">)</span><span class="p">.</span></code></pre><h2 id="removing-a-macro-definition" class="section-heading">
│ │ │    <a href="#removing-a-macro-definition" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Removing a macro definition</span>
│ │ │  </h2>
│ │ │ -<p>A definition of macro can be removed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">undef</span><span class="p" data-group-id="6660008771-1">(</span><span class="n">Macro</span><span class="p" data-group-id="6660008771-1">)</span><span class="p">.</span></code></pre><h2 id="conditional-compilation" class="section-heading">
│ │ │ +<p>A definition of macro can be removed as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">undef</span><span class="p" data-group-id="9199143375-1">(</span><span class="n">Macro</span><span class="p" data-group-id="9199143375-1">)</span><span class="p">.</span></code></pre><h2 id="conditional-compilation" class="section-heading">
│ │ │    <a href="#conditional-compilation" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Conditional Compilation</span>
│ │ │  </h2>
│ │ │  <p>The following macro directives support conditional compilation:</p><ul><li><p><strong><code class="inline">-ifdef(Macro).</code></strong> - Evaluate the following lines only if <code class="inline">Macro</code> is
│ │ │  defined.</p></li><li><p><strong><code class="inline">-ifndef(Macro).</code></strong> - Evaluate the following lines only if <code class="inline">Macro</code> is not
│ │ │ @@ -219,43 +219,43 @@
│ │ │  true, and the <code class="inline">Condition</code> evaluates to true, the lines following the <code class="inline">elif</code>
│ │ │  are evaluated instead.</p></li><li><p><strong><code class="inline">-endif.</code></strong> - Specifies the end of a series of control flow directives.</p></li></ul><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Macro directives cannot be used inside functions.</p></section><p>Syntactically, the <code class="inline">Condition</code> in <code class="inline">if</code> and <code class="inline">elif</code> must be a
│ │ │  <a href="expressions.html#guard-expressions">guard expression</a>. Other constructs (such as
│ │ │  a <code class="inline">case</code> expression) result in a compilation error.</p><p>As opposed to the standard guard expressions, an expression in an <code class="inline">if</code> and
│ │ │  <code class="inline">elif</code> also supports calling the psuedo-function <code class="inline">defined(Name)</code>, which tests
│ │ │  whether the <code class="inline">Name</code> argument is the name of a previously defined macro.
│ │ │  <code class="inline">defined(Name)</code> evaluates to <code class="inline">true</code> if the macro is defined and <code class="inline">false</code>
│ │ │ -otherwise. An attempt to call other functions results in a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3691567886-1">(</span><span class="ss">m</span><span class="p" data-group-id="3691567886-1">)</span><span class="p">.</span><span class="w">
│ │ │ +otherwise. An attempt to call other functions results in a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6739100122-1">(</span><span class="ss">m</span><span class="p" data-group-id="6739100122-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="3691567886-2">(</span><span class="ss">debug</span><span class="p" data-group-id="3691567886-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3691567886-3">(</span><span class="n">LOG</span><span class="p" data-group-id="3691567886-4">(</span><span class="n">X</span><span class="p" data-group-id="3691567886-4">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3691567886-5">(</span><span class="s">&quot;{</span><span class="si">~p</span><span class="s">,</span><span class="si">~p</span><span class="s">}: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3691567886-6">[</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="o">?</span><span class="n">LINE</span><span class="p">,</span><span class="n">X</span><span class="p" data-group-id="3691567886-6">]</span><span class="p" data-group-id="3691567886-5">)</span><span class="p" data-group-id="3691567886-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="6739100122-2">(</span><span class="ss">debug</span><span class="p" data-group-id="6739100122-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6739100122-3">(</span><span class="n">LOG</span><span class="p" data-group-id="6739100122-4">(</span><span class="n">X</span><span class="p" data-group-id="6739100122-4">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6739100122-5">(</span><span class="s">&quot;{</span><span class="si">~p</span><span class="s">,</span><span class="si">~p</span><span class="s">}: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6739100122-6">[</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="o">?</span><span class="n">LINE</span><span class="p">,</span><span class="n">X</span><span class="p" data-group-id="6739100122-6">]</span><span class="p" data-group-id="6739100122-5">)</span><span class="p" data-group-id="6739100122-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3691567886-7">(</span><span class="n">LOG</span><span class="p" data-group-id="3691567886-8">(</span><span class="n">X</span><span class="p" data-group-id="3691567886-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3691567886-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6739100122-7">(</span><span class="n">LOG</span><span class="p" data-group-id="6739100122-8">(</span><span class="n">X</span><span class="p" data-group-id="6739100122-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6739100122-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>When trace output is desired, <code class="inline">debug</code> is to be defined when the module <code class="inline">m</code> is
│ │ │  compiled:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erlc -Ddebug m.erl</span><span class="w">
│ │ │  
│ │ │  </span><span class="ow">or</span><span class="w">
│ │ │  
│ │ │ -</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="8457147015-1">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8457147015-2">{</span><span class="ss">d</span><span class="p">,</span><span class="w"> </span><span class="ss">debug</span><span class="p" data-group-id="8457147015-2">}</span><span class="p" data-group-id="8457147015-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8457147015-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">m</span><span class="p" data-group-id="8457147015-3">}</span></code></pre><p><code class="inline">?LOG(Arg)</code> is then expanded to a call to <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> and provide the user
│ │ │ -with some simple trace output.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8606286907-1">(</span><span class="ss">m</span><span class="p" data-group-id="8606286907-1">)</span><span class="w">
│ │ │ +</span><span class="mi">1</span><span class="o">&gt;</span><span class="w"> </span><span class="nf">c</span><span class="p" data-group-id="8327340993-1">(</span><span class="ss">m</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8327340993-2">{</span><span class="ss">d</span><span class="p">,</span><span class="w"> </span><span class="ss">debug</span><span class="p" data-group-id="8327340993-2">}</span><span class="p" data-group-id="8327340993-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8327340993-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">m</span><span class="p" data-group-id="8327340993-3">}</span></code></pre><p><code class="inline">?LOG(Arg)</code> is then expanded to a call to <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> and provide the user
│ │ │ +with some simple trace output.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3964658573-1">(</span><span class="ss">m</span><span class="p" data-group-id="3964658573-1">)</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="8606286907-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">25</span><span class="p" data-group-id="8606286907-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="3964658573-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">25</span><span class="p" data-group-id="3964658573-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% Code that will work in OTP 25 or higher</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">elif</span><span class="p" data-group-id="8606286907-3">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="p" data-group-id="8606286907-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">elif</span><span class="p" data-group-id="3964658573-3">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="p" data-group-id="3964658573-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% Code that will work in OTP 26 or higher</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% Code that will work in OTP 24 or lower.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This code uses the <code class="inline">OTP_RELEASE</code> macro to conditionally select code depending on
│ │ │ -release.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3151714497-1">(</span><span class="ss">m</span><span class="p" data-group-id="3151714497-1">)</span><span class="w">
│ │ │ +release.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4909575712-1">(</span><span class="ss">m</span><span class="p" data-group-id="4909575712-1">)</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="3151714497-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">defined</span><span class="p" data-group-id="3151714497-3">(</span><span class="ss">debug</span><span class="p" data-group-id="3151714497-3">)</span><span class="p" data-group-id="3151714497-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">if</span><span class="p" data-group-id="4909575712-2">(</span><span class="o">?</span><span class="n">OTP_RELEASE</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mi">26</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">defined</span><span class="p" data-group-id="4909575712-3">(</span><span class="ss">debug</span><span class="p" data-group-id="4909575712-3">)</span><span class="p" data-group-id="4909575712-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% Debugging code that requires OTP 26 or later.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% Non-debug code that works in any release.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>This code uses the <code class="inline">OTP_RELEASE</code> macro and <code class="inline">defined(debug)</code> to compile debug
│ │ │  code only for OTP 26 or later.</p><h2 id="the-feature-directive" class="section-heading">
│ │ │    <a href="#the-feature-directive" class="hover-link">
│ │ │ @@ -270,44 +270,44 @@
│ │ │  used. In practice this means it should appear before any <code class="inline">-export(..)</code> or record
│ │ │  definitions.</p><h2 id="error-and-warning-directives" class="section-heading">
│ │ │    <a href="#error-and-warning-directives" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">-error() and -warning() directives</span>
│ │ │  </h2>
│ │ │ -<p>The directive <code class="inline">-error(Term)</code> causes a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0253086363-1">(</span><span class="ss">t</span><span class="p" data-group-id="0253086363-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0253086363-2">(</span><span class="p" data-group-id="0253086363-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0253086363-3">]</span><span class="p" data-group-id="0253086363-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>The directive <code class="inline">-error(Term)</code> causes a compilation error.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7545176880-1">(</span><span class="ss">t</span><span class="p" data-group-id="7545176880-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7545176880-2">(</span><span class="p" data-group-id="7545176880-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7545176880-3">]</span><span class="p" data-group-id="7545176880-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="0253086363-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="0253086363-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">version</span><span class="p" data-group-id="0253086363-5">(</span><span class="p" data-group-id="0253086363-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">ifdef</span><span class="p" data-group-id="7545176880-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="7545176880-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">version</span><span class="p" data-group-id="7545176880-5">(</span><span class="p" data-group-id="7545176880-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">else</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">error</span><span class="p" data-group-id="0253086363-6">(</span><span class="s">&quot;Macro VERSION must be defined.&quot;</span><span class="p" data-group-id="0253086363-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">version</span><span class="p" data-group-id="0253086363-7">(</span><span class="p" data-group-id="0253086363-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">error</span><span class="p" data-group-id="7545176880-6">(</span><span class="s">&quot;Macro VERSION must be defined.&quot;</span><span class="p" data-group-id="7545176880-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">version</span><span class="p" data-group-id="7545176880-7">(</span><span class="p" data-group-id="7545176880-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span></code></pre><p>The error message will look like this:</p><pre><code class="text">% erlc t.erl
│ │ │ -t.erl:7: -error(&quot;Macro VERSION must be defined.&quot;).</code></pre><p>The directive <code class="inline">-warning(Term)</code> causes a compilation warning.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9105653452-1">(</span><span class="ss">t</span><span class="p" data-group-id="9105653452-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9105653452-2">(</span><span class="p" data-group-id="9105653452-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9105653452-3">]</span><span class="p" data-group-id="9105653452-2">)</span><span class="p">.</span><span class="w">
│ │ │ +t.erl:7: -error(&quot;Macro VERSION must be defined.&quot;).</code></pre><p>The directive <code class="inline">-warning(Term)</code> causes a compilation warning.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0608223427-1">(</span><span class="ss">t</span><span class="p" data-group-id="0608223427-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0608223427-2">(</span><span class="p" data-group-id="0608223427-3">[</span><span class="ss">version</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0608223427-3">]</span><span class="p" data-group-id="0608223427-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">ifndef</span><span class="p" data-group-id="9105653452-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="9105653452-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">warning</span><span class="p" data-group-id="9105653452-5">(</span><span class="s">&quot;Macro VERSION not defined -- using default version.&quot;</span><span class="p" data-group-id="9105653452-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9105653452-6">(</span><span class="n">VERSION</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;0&quot;</span><span class="p" data-group-id="9105653452-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">ifndef</span><span class="p" data-group-id="0608223427-4">(</span><span class="n">VERSION</span><span class="p" data-group-id="0608223427-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">warning</span><span class="p" data-group-id="0608223427-5">(</span><span class="s">&quot;Macro VERSION not defined -- using default version.&quot;</span><span class="p" data-group-id="0608223427-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="0608223427-6">(</span><span class="n">VERSION</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;0&quot;</span><span class="p" data-group-id="0608223427-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">endif</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">version</span><span class="p" data-group-id="9105653452-7">(</span><span class="p" data-group-id="9105653452-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span></code></pre><p>The warning message will look like this:</p><pre><code class="text">% erlc t.erl
│ │ │ +</span><span class="nf">version</span><span class="p" data-group-id="0608223427-7">(</span><span class="p" data-group-id="0608223427-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VERSION</span><span class="p">.</span></code></pre><p>The warning message will look like this:</p><pre><code class="text">% erlc t.erl
│ │ │  t.erl:5: Warning: -warning(&quot;Macro VERSION not defined -- using default version.&quot;).</code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>The <code class="inline">-error()</code> and <code class="inline">-warning()</code> directives were added in Erlang/OTP 19.</p></section><h2 id="stringifying-macro-arguments" class="section-heading">
│ │ │    <a href="#stringifying-macro-arguments" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Stringifying Macro Arguments</span>
│ │ │  </h2>
│ │ │  <p>The construction <code class="inline">??Arg</code>, where <code class="inline">Arg</code> is a macro argument, is expanded to a
│ │ │  string containing the tokens of the argument. This is similar to the <code class="inline">#arg</code>
│ │ │ -stringifying construction in C.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6015668343-1">(</span><span class="n">TESTCALL</span><span class="p" data-group-id="6015668343-2">(</span><span class="n">Call</span><span class="p" data-group-id="6015668343-2">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6015668343-3">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6015668343-4">[</span><span class="o">?</span><span class="o">?</span><span class="n">Call</span><span class="p">,</span><span class="w"> </span><span class="n">Call</span><span class="p" data-group-id="6015668343-4">]</span><span class="p" data-group-id="6015668343-3">)</span><span class="p" data-group-id="6015668343-1">)</span><span class="p">.</span><span class="w">
│ │ │ +stringifying construction in C.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3084583930-1">(</span><span class="n">TESTCALL</span><span class="p" data-group-id="3084583930-2">(</span><span class="n">Call</span><span class="p" data-group-id="3084583930-2">)</span><span class="p">,</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3084583930-3">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3084583930-4">[</span><span class="o">?</span><span class="o">?</span><span class="n">Call</span><span class="p">,</span><span class="w"> </span><span class="n">Call</span><span class="p" data-group-id="3084583930-4">]</span><span class="p" data-group-id="3084583930-3">)</span><span class="p" data-group-id="3084583930-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="6015668343-5">(</span><span class="nf">myfunction</span><span class="p" data-group-id="6015668343-6">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6015668343-6">)</span><span class="p" data-group-id="6015668343-5">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="6015668343-7">(</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="6015668343-8">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="6015668343-8">)</span><span class="p" data-group-id="6015668343-7">)</span><span class="p">.</span></code></pre><p>results in</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6922384305-1">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="6922384305-2">[</span><span class="s">&quot;myfunction ( 1 , 2 )&quot;</span><span class="p">,</span><span class="nf">myfunction</span><span class="p" data-group-id="6922384305-3">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6922384305-3">)</span><span class="p" data-group-id="6922384305-2">]</span><span class="p" data-group-id="6922384305-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6922384305-4">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="6922384305-5">[</span><span class="s">&quot;you : function ( 2 , 1 )&quot;</span><span class="p">,</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="6922384305-6">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="6922384305-6">)</span><span class="p" data-group-id="6922384305-5">]</span><span class="p" data-group-id="6922384305-4">)</span><span class="p">.</span></code></pre><p>That is, a trace output, with both the function called and the resulting value.</p>
│ │ │ +</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="3084583930-5">(</span><span class="nf">myfunction</span><span class="p" data-group-id="3084583930-6">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3084583930-6">)</span><span class="p" data-group-id="3084583930-5">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="o">?</span><span class="n">TESTCALL</span><span class="p" data-group-id="3084583930-7">(</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="3084583930-8">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3084583930-8">)</span><span class="p" data-group-id="3084583930-7">)</span><span class="p">.</span></code></pre><p>results in</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9412432367-1">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9412432367-2">[</span><span class="s">&quot;myfunction ( 1 , 2 )&quot;</span><span class="p">,</span><span class="nf">myfunction</span><span class="p" data-group-id="9412432367-3">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9412432367-3">)</span><span class="p" data-group-id="9412432367-2">]</span><span class="p" data-group-id="9412432367-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9412432367-4">(</span><span class="s">&quot;Call </span><span class="si">~s</span><span class="s">: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="9412432367-5">[</span><span class="s">&quot;you : function ( 2 , 1 )&quot;</span><span class="p">,</span><span class="nc">you</span><span class="p">:</span><span class="nf">function</span><span class="p" data-group-id="9412432367-6">(</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9412432367-6">)</span><span class="p" data-group-id="9412432367-5">]</span><span class="p" data-group-id="9412432367-4">)</span><span class="p">.</span></code></pre><p>That is, a trace output, with both the function called and the resulting value.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="expressions.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/maps.html
│ │ │ @@ -148,16 +148,16 @@
│ │ │  single function that constructs the map using the map syntax and always use
│ │ │  it.</p></li><li><p>Always update the map using the <code class="inline">:=</code> operator (that is, requiring that an
│ │ │  element with that key already exists). The <code class="inline">:=</code> operator is slightly more
│ │ │  efficient, and it helps catching mispellings of keys.</p></li><li><p>Whenever possible, match multiple map elements at once.</p></li><li><p>Whenever possible, update multiple map elements at once.</p></li><li><p>Avoid default values and the <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> function. If there are default
│ │ │  values, sharing of keys between different instances of the map will be less
│ │ │  effective, and it is not possible to match multiple elements having default
│ │ │  values in one go.</p></li><li><p>To avoid having to deal with a map that may lack some keys, <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#merge/2"><code class="inline">maps:merge/2</code></a> can
│ │ │ -efficiently add multiple default values. For example:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1526946500-1">#{</span><span class="ss">shoe_size</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="ss">editor</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">emacs</span><span class="p" data-group-id="1526946500-1">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="1526946500-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="1526946500-2">)</span></code></pre></li></ul><h2 id="using-maps-as-dictionaries" class="section-heading">
│ │ │ +efficiently add multiple default values. For example:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7506033420-1">#{</span><span class="ss">shoe_size</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="ss">editor</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">emacs</span><span class="p" data-group-id="7506033420-1">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="7506033420-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="7506033420-2">)</span></code></pre></li></ul><h2 id="using-maps-as-dictionaries" class="section-heading">
│ │ │    <a href="#using-maps-as-dictionaries" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Using Maps as Dictionaries</span>
│ │ │  </h2>
│ │ │  <p>Using a map as a dictionary implies the following usage pattern:</p><ul><li>Keys are usually variables not known at compile-time.</li><li>There can be any number of elements in the map.</li><li>Usually, no more than one element is looked up or updated at once.</li></ul><p>Given that usage pattern, the difference in performance between using the map
│ │ │  syntax and the maps module is usually small. Therefore, which one to use is
│ │ │ @@ -167,18 +167,18 @@
│ │ │  choice.</li></ul><h2 id="using-maps-as-sets" class="section-heading">
│ │ │    <a href="#using-maps-as-sets" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Using Maps as Sets</span>
│ │ │  </h2>
│ │ │  <p>Starting in OTP 24, the <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html"><code class="inline">sets</code></a> module has an option to represent sets as maps.
│ │ │ -Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="1392331389-1">(</span><span class="p" data-group-id="1392331389-2">[</span><span class="p" data-group-id="1392331389-3">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1392331389-3">}</span><span class="p" data-group-id="1392331389-2">]</span><span class="p" data-group-id="1392331389-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1392331389-4">#{</span><span class="p" data-group-id="1392331389-4">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">from_list</span><span class="p" data-group-id="1392331389-5">(</span><span class="p" data-group-id="1392331389-6">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="1392331389-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1392331389-7">[</span><span class="p" data-group-id="1392331389-8">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1392331389-8">}</span><span class="p" data-group-id="1392331389-7">]</span><span class="p" data-group-id="1392331389-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1392331389-9">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1392331389-10">[</span><span class="p" data-group-id="1392331389-10">]</span><span class="p">,</span><span class="ss">y</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1392331389-11">[</span><span class="p" data-group-id="1392331389-11">]</span><span class="p">,</span><span class="ss">z</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1392331389-12">[</span><span class="p" data-group-id="1392331389-12">]</span><span class="p" data-group-id="1392331389-9">}</span></code></pre><p><code class="inline">sets</code> backed by maps is generally the most efficient set representation, with a
│ │ │ +Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="2727528190-1">(</span><span class="p" data-group-id="2727528190-2">[</span><span class="p" data-group-id="2727528190-3">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2727528190-3">}</span><span class="p" data-group-id="2727528190-2">]</span><span class="p" data-group-id="2727528190-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2727528190-4">#{</span><span class="p" data-group-id="2727528190-4">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">sets</span><span class="p">:</span><span class="nf">from_list</span><span class="p" data-group-id="2727528190-5">(</span><span class="p" data-group-id="2727528190-6">[</span><span class="ss">x</span><span class="p">,</span><span class="ss">y</span><span class="p">,</span><span class="ss">z</span><span class="p" data-group-id="2727528190-6">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2727528190-7">[</span><span class="p" data-group-id="2727528190-8">{</span><span class="ss">version</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2727528190-8">}</span><span class="p" data-group-id="2727528190-7">]</span><span class="p" data-group-id="2727528190-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2727528190-9">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2727528190-10">[</span><span class="p" data-group-id="2727528190-10">]</span><span class="p">,</span><span class="ss">y</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2727528190-11">[</span><span class="p" data-group-id="2727528190-11">]</span><span class="p">,</span><span class="ss">z</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2727528190-12">[</span><span class="p" data-group-id="2727528190-12">]</span><span class="p" data-group-id="2727528190-9">}</span></code></pre><p><code class="inline">sets</code> backed by maps is generally the most efficient set representation, with a
│ │ │  few possible exceptions:</p><ul><li><a href="../../lib/stdlib-6.2.2.2/doc/html/ordsets.html#intersection/2"><code class="inline">ordsets:intersection/2</code></a> can be more efficient than <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html#intersection/2"><code class="inline">sets:intersection/2</code></a>. If
│ │ │  the intersection operation is frequently used and operations that operate on a
│ │ │  single element in a set (such as <code class="inline">is_element/2</code>) are avoided, <a href="../../lib/stdlib-6.2.2.2/doc/html/ordsets.html"><code class="inline">ordsets</code></a> can
│ │ │  be a better choice than <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html"><code class="inline">sets</code></a>.</li><li>If the intersection operation is frequently used and operations that operate
│ │ │  on a single element in a set (such as <code class="inline">is_element/2</code>) must also be efficient,
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gb_sets.html"><code class="inline">gb_sets</code></a> can potentially be a better choice than <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html"><code class="inline">sets</code></a>.</li><li>If the elements of the set are integers in a fairly compact range, the set can
│ │ │  be represented as an integer where each bit represents an element in the set.
│ │ │ @@ -203,18 +203,18 @@
│ │ │  for the runtime system).</p></li><li><p><strong>N</strong> - The number of elements in the map.</p></li><li><p><strong>Keys</strong> - A tuple with keys of the map: <code class="inline">{Key1,...,KeyN}</code>. The keys are
│ │ │  sorted.</p></li><li><p><strong>Value1</strong> - The value corresponding to the first key in the key tuple.</p></li><li><p><strong>ValueN</strong> - The value corresponding to the last key in the key tuple.</p></li></ul><p>As an example, let us look at how the map <code class="inline">#{a =&gt; foo, z =&gt; bar}</code> is
│ │ │  represented:</p><table><thead><tr><th style="text-align: center;">0</th><th style="text-align: left;">1</th><th style="text-align: center;">2</th><th style="text-align: center;">3</th><th style="text-align: left;">4</th></tr></thead><tbody><tr><td style="text-align: center;"><strong>FLATMAP</strong></td><td style="text-align: left;"><em>2</em></td><td style="text-align: center;"><code class="inline">{a,z}</code></td><td style="text-align: center;"><code class="inline">foo</code></td><td style="text-align: left;"><code class="inline">bar</code></td></tr></tbody></table><p><em>Table: #{a =&gt; foo, z =&gt; bar}</em></p><p>Let us update the map: <code class="inline">M#{q =&gt; baz}</code>. The map now looks like this:</p><table><thead><tr><th style="text-align: center;">0</th><th style="text-align: left;">1</th><th style="text-align: center;">2</th><th style="text-align: center;">3</th><th style="text-align: center;">4</th><th style="text-align: center;">5</th></tr></thead><tbody><tr><td style="text-align: center;"><strong>FLATMAP</strong></td><td style="text-align: left;"><em>3</em></td><td style="text-align: center;"><code class="inline">{a,q,z}</code></td><td style="text-align: center;"><code class="inline">foo</code></td><td style="text-align: center;"><code class="inline">baz</code></td><td style="text-align: center;"><code class="inline">bar</code></td></tr></tbody></table><p><em>Table: #{a =&gt; foo, q =&gt; baz, z =&gt; bar}</em></p><p>Finally, change the value of one element: <code class="inline">M#{z := bird}</code>. The map now looks
│ │ │  like this:</p><table><thead><tr><th style="text-align: center;">0</th><th style="text-align: left;">1</th><th style="text-align: center;">2</th><th style="text-align: center;">3</th><th style="text-align: center;">4</th><th style="text-align: center;">5</th></tr></thead><tbody><tr><td style="text-align: center;"><strong>FLATMAP</strong></td><td style="text-align: left;"><em>3</em></td><td style="text-align: center;"><code class="inline">{a,q,z}</code></td><td style="text-align: center;"><code class="inline">foo</code></td><td style="text-align: center;"><code class="inline">baz</code></td><td style="text-align: center;"><code class="inline">bird</code></td></tr></tbody></table><p><em>Table: #{a =&gt; foo, q =&gt; baz, z =&gt; bird}</em></p><p>When the value for an existing key is updated, the key tuple is not updated,
│ │ │  allowing the key tuple to be shared with other instances of the map that have
│ │ │  the same keys. In fact, the key tuple can be shared between all maps with the
│ │ │  same keys with some care. To arrange that, define a function that returns a map.
│ │ │ -For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="1023762318-1">(</span><span class="p" data-group-id="1023762318-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1023762318-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p" data-group-id="1023762318-2">}</span><span class="p">.</span></code></pre><p>Defined like this, the key tuple <code class="inline">{a,b,c}</code> will be a global literal. To ensure
│ │ │ +For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="5454213965-1">(</span><span class="p" data-group-id="5454213965-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5454213965-2">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">default</span><span class="p" data-group-id="5454213965-2">}</span><span class="p">.</span></code></pre><p>Defined like this, the key tuple <code class="inline">{a,b,c}</code> will be a global literal. To ensure
│ │ │  that the key tuple is shared when creating an instance of the map, always call
│ │ │ -<code class="inline">new()</code> and modify the returned map:</p><pre><code class="makeup erlang" translate="no"><span class="w">    </span><span class="p" data-group-id="9415315331-1">(</span><span class="n">SOME_MODULE</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="9415315331-2">(</span><span class="p" data-group-id="9415315331-2">)</span><span class="p" data-group-id="9415315331-1">)</span><span class="p" data-group-id="9415315331-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="9415315331-3">}</span><span class="p">.</span></code></pre><p>Using the map syntax with small maps is particularly efficient. As long as the
│ │ │ +<code class="inline">new()</code> and modify the returned map:</p><pre><code class="makeup erlang" translate="no"><span class="w">    </span><span class="p" data-group-id="7164529628-1">(</span><span class="n">SOME_MODULE</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="7164529628-2">(</span><span class="p" data-group-id="7164529628-2">)</span><span class="p" data-group-id="7164529628-1">)</span><span class="p" data-group-id="7164529628-3">#{</span><span class="ss">a</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="7164529628-3">}</span><span class="p">.</span></code></pre><p>Using the map syntax with small maps is particularly efficient. As long as the
│ │ │  keys are known at compile-time, the map is updated in one go, making the time to
│ │ │  update a map essentially constant regardless of the number of keys updated. The
│ │ │  same goes for matching. (When the keys are variables, one or more of the keys
│ │ │  could be identical, so the operations need to be performed sequentially from
│ │ │  left to right.)</p><p>The memory size for a small map is the size of all keys and values plus 5 words.
│ │ │  See <a href="memory.html">Memory</a> for more information about memory sizes.</p><h3 id="how-large-maps-are-implemented" class="section-heading">
│ │ │    <a href="#how-large-maps-are-implemented" class="hover-link">
│ │ │ @@ -241,21 +241,21 @@
│ │ │    <a href="#using-the-map-syntax" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Using the Map Syntax</span>
│ │ │  </h2>
│ │ │  <p>Using the map syntax is usually slightly more efficient than using the
│ │ │  corresponding function in the <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html"><code class="inline">maps</code></a> module.</p><p>The gain in efficiency for the map syntax is more noticeable for the following
│ │ │ -operations that can only be achieved using the map syntax:</p><ul><li>Matching multiple literal keys</li><li>Updating multiple literal keys</li><li>Adding multiple literal keys to a map</li></ul><p>For example:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="8031280588-1">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="ss">z</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="8031280588-1">}</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="5167461020-1">(</span><span class="ss">x</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="5167461020-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="5167461020-2">(</span><span class="ss">y</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="5167461020-2">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="5167461020-3">(</span><span class="ss">z</span><span class="p">,</span><span class="w"> </span><span class="n">Z</span><span class="p">,</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="5167461020-3">)</span></code></pre><p>If the map is a small map, the first example runs roughly three times as fast.</p><p>Note that for variable keys, the elements are updated sequentially from left to
│ │ │ -right. For example, given the following update with variable keys:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="4102812980-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="4102812980-1">}</span></code></pre><p>the compiler rewrites it like this to ensure that the updates are applied from
│ │ │ -left to right:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="7209895434-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="7209895434-1">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="7209895434-2">#{</span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7209895434-2">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="7209895434-3">#{</span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="7209895434-3">}</span></code></pre><p>If a key is known to exist in a map, using the <code class="inline">:=</code> operator is slightly more
│ │ │ +operations that can only be achieved using the map syntax:</p><ul><li>Matching multiple literal keys</li><li>Updating multiple literal keys</li><li>Adding multiple literal keys to a map</li></ul><p>For example:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="0371818845-1">#{</span><span class="ss">x</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="ss">z</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="0371818845-1">}</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="3491380012-1">(</span><span class="ss">x</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="3491380012-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="3491380012-2">(</span><span class="ss">y</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="3491380012-2">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">update</span><span class="p" data-group-id="3491380012-3">(</span><span class="ss">z</span><span class="p">,</span><span class="w"> </span><span class="n">Z</span><span class="p">,</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="3491380012-3">)</span></code></pre><p>If the map is a small map, the first example runs roughly three times as fast.</p><p>Note that for variable keys, the elements are updated sequentially from left to
│ │ │ +right. For example, given the following update with variable keys:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="2063339881-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="2063339881-1">}</span></code></pre><p>the compiler rewrites it like this to ensure that the updates are applied from
│ │ │ +left to right:</p><pre><code class="makeup erlang" translate="no"><span class="n">Map2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map1</span><span class="p" data-group-id="6824902130-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6824902130-1">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Map3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map2</span><span class="p" data-group-id="6824902130-2">#{</span><span class="n">Key2</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6824902130-2">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Map3</span><span class="p" data-group-id="6824902130-3">#{</span><span class="n">Key3</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="6824902130-3">}</span></code></pre><p>If a key is known to exist in a map, using the <code class="inline">:=</code> operator is slightly more
│ │ │  efficient than using the <code class="inline">=&gt;</code> operator for a small map.</p><h2 id="using-the-functions-in-the-maps-module" class="section-heading">
│ │ │    <a href="#using-the-functions-in-the-maps-module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Using the Functions in the maps Module</span>
│ │ │  </h2>
│ │ │  <p>Here follows some notes about most of the functions in the <code class="inline">maps</code> module. For
│ │ │ @@ -306,23 +306,23 @@
│ │ │    <a href="#maps-get-3" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">maps:get/3</span>
│ │ │  </h3>
│ │ │  <p>As an optimization, the compiler will rewrite a call to <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> to Erlang
│ │ │  code similar to the following:</p><pre><code class="makeup erlang" translate="no"><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="n">Map</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="5252401203-1">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="5252401203-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="p">;</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="5252401203-2">#{</span><span class="p" data-group-id="5252401203-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Default</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="1008460923-1">#{</span><span class="n">Key</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Value</span><span class="p" data-group-id="1008460923-1">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Value</span><span class="p">;</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="1008460923-2">#{</span><span class="p" data-group-id="1008460923-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Default</span><span class="w">
│ │ │           </span><span class="k">end</span></code></pre><p>This is reasonably efficient, but if a small map is used as an alternative to
│ │ │  using a record it is often better not to rely on default values as it prevents
│ │ │  sharing of keys, which may in the end use more memory than what you save from
│ │ │  not storing default values in the map.</p><p>If default values are nevertheless required, instead of calling <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a>
│ │ │  multiple times, consider putting the default values in a map and merging that
│ │ │ -map with the other map:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7107931407-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">KeyN</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueN</span><span class="p" data-group-id="7107931407-1">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="7107931407-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="7107931407-2">)</span></code></pre><p>This helps share keys between the default map and the one you applied defaults
│ │ │ +map with the other map:</p><pre><code class="makeup erlang" translate="no"><span class="n">DefaultMap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9151768056-1">#{</span><span class="n">Key1</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Value2</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">KeyN</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">ValueN</span><span class="p" data-group-id="9151768056-1">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">MapWithDefaultsApplied</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">merge</span><span class="p" data-group-id="9151768056-2">(</span><span class="n">DefaultMap</span><span class="p">,</span><span class="w"> </span><span class="n">OtherMap</span><span class="p" data-group-id="9151768056-2">)</span></code></pre><p>This helps share keys between the default map and the one you applied defaults
│ │ │  to, as long as the default map contains <em>all</em> the keys that will ever be used
│ │ │  and not just the ones with default values. Whether this is faster than calling
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> multiple times depends on the size of the map and the number of
│ │ │  default values.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before OTP 26.0 <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html#get/3"><code class="inline">maps:get/3</code></a> was implemented by calling the function instead
│ │ │  of rewriting it as an Erlang expression. It is now slightly faster but can no
│ │ │  longer be traced.</p></section><h3 id="maps-intersect-2-maps-intersect_with-3" class="section-heading">
│ │ │    <a href="#maps-intersect-2-maps-intersect_with-3" class="hover-link">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/modules.html
│ │ │ @@ -118,20 +118,20 @@
│ │ │  <h2 id="module-syntax" class="section-heading">
│ │ │    <a href="#module-syntax" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Module Syntax</span>
│ │ │  </h2>
│ │ │  <p>Erlang code is divided into <em>modules</em>. A module consists of a sequence of
│ │ │ -attributes and function declarations, each terminated by a period (<code class="inline">.</code>).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6766929335-1">(</span><span class="ss">m</span><span class="p" data-group-id="6766929335-1">)</span><span class="p">.</span><span class="w">          </span><span class="c1">% module attribute</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6766929335-2">(</span><span class="p" data-group-id="6766929335-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6766929335-3">]</span><span class="p" data-group-id="6766929335-2">)</span><span class="p">.</span><span class="w">   </span><span class="c1">% module attribute</span><span class="w">
│ │ │ +attributes and function declarations, each terminated by a period (<code class="inline">.</code>).</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6306168319-1">(</span><span class="ss">m</span><span class="p" data-group-id="6306168319-1">)</span><span class="p">.</span><span class="w">          </span><span class="c1">% module attribute</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6306168319-2">(</span><span class="p" data-group-id="6306168319-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6306168319-3">]</span><span class="p" data-group-id="6306168319-2">)</span><span class="p">.</span><span class="w">   </span><span class="c1">% module attribute</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="6766929335-4">(</span><span class="n">N</span><span class="p" data-group-id="6766929335-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="o">&gt;</span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% beginning of function declaration</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="6766929335-5">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="6766929335-5">)</span><span class="p">;</span><span class="w">   </span><span class="c1">%  |</span><span class="w">
│ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="6766929335-6">(</span><span class="mi">0</span><span class="p" data-group-id="6766929335-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">           </span><span class="c1">%  |</span><span class="w">
│ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="6306168319-4">(</span><span class="n">N</span><span class="p" data-group-id="6306168319-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="o">&gt;</span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% beginning of function declaration</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="6306168319-5">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="6306168319-5">)</span><span class="p">;</span><span class="w">   </span><span class="c1">%  |</span><span class="w">
│ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="6306168319-6">(</span><span class="mi">0</span><span class="p" data-group-id="6306168319-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">           </span><span class="c1">%  |</span><span class="w">
│ │ │      </span><span class="mi">1</span><span class="p">.</span><span class="w">               </span><span class="c1">% end of function declaration</span></code></pre><p>For a description of function declarations, see
│ │ │  <a href="ref_man_functions.html">Function Declaration Syntax</a>.</p><h2 id="module-attributes" class="section-heading">
│ │ │    <a href="#module-attributes" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Module Attributes</span>
│ │ │  </h2>
│ │ │ @@ -176,71 +176,71 @@
│ │ │  meaning.</p></section></li></ul><h3 id="behaviour-module-attribute" class="section-heading">
│ │ │    <a href="#behaviour-module-attribute" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Behaviour Module Attribute</span>
│ │ │  </h3>
│ │ │  <p>It is possible to specify that the module is the callback module for a
│ │ │ -<em>behaviour</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9660382160-1">(</span><span class="n">Behaviour</span><span class="p" data-group-id="9660382160-1">)</span><span class="p">.</span></code></pre><p>The atom <code class="inline">Behaviour</code> gives the name of the behaviour, which can be a
│ │ │ +<em>behaviour</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="0903500732-1">(</span><span class="n">Behaviour</span><span class="p" data-group-id="0903500732-1">)</span><span class="p">.</span></code></pre><p>The atom <code class="inline">Behaviour</code> gives the name of the behaviour, which can be a
│ │ │  user-defined behaviour or one of the following OTP standard behaviours:</p><ul><li><code class="inline">gen_server</code></li><li><code class="inline">gen_statem</code></li><li><code class="inline">gen_event</code></li><li><code class="inline">supervisor</code></li></ul><p>The spelling <code class="inline">behavior</code> is also accepted.</p><p>The callback functions of the module can be specified either directly by the
│ │ │ -exported function <code class="inline">behaviour_info/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="9698997863-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="9698997863-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Callbacks</span><span class="p">.</span></code></pre><p>or by a <code class="inline">-callback</code> attribute for each callback function:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="1455851861-1">(</span><span class="n">Arguments</span><span class="p" data-group-id="1455851861-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="p">.</span></code></pre><p>Here, <code class="inline">Arguments</code> is a list of zero or more arguments. The <code class="inline">-callback</code> attribute
│ │ │ +exported function <code class="inline">behaviour_info/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="4968273398-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="4968273398-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Callbacks</span><span class="p">.</span></code></pre><p>or by a <code class="inline">-callback</code> attribute for each callback function:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="2840494458-1">(</span><span class="n">Arguments</span><span class="p" data-group-id="2840494458-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="p">.</span></code></pre><p>Here, <code class="inline">Arguments</code> is a list of zero or more arguments. The <code class="inline">-callback</code> attribute
│ │ │  is to be preferred since the extra type information can be used by tools to
│ │ │  produce documentation or find discrepancies.</p><p>Read more about behaviours and callback modules in
│ │ │  <a href="../../doc/system/spec_proc.html#behaviours">OTP Design Principles</a>.</p><h3 id="record-definitions" class="section-heading">
│ │ │    <a href="#record-definitions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Record Definitions</span>
│ │ │  </h3>
│ │ │ -<p>The same syntax as for module attributes is used for record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5846653809-1">(</span><span class="n">Record</span><span class="p">,</span><span class="w"> </span><span class="n">Fields</span><span class="p" data-group-id="5846653809-1">)</span><span class="p">.</span></code></pre><p>Record definitions are allowed anywhere in a module, also among the function
│ │ │ +<p>The same syntax as for module attributes is used for record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4452502694-1">(</span><span class="n">Record</span><span class="p">,</span><span class="w"> </span><span class="n">Fields</span><span class="p" data-group-id="4452502694-1">)</span><span class="p">.</span></code></pre><p>Record definitions are allowed anywhere in a module, also among the function
│ │ │  declarations. Read more in <a href="ref_man_records.html">Records</a>.</p><h3 id="preprocessor" class="section-heading">
│ │ │    <a href="#preprocessor" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Preprocessor</span>
│ │ │  </h3>
│ │ │  <p>The same syntax as for module attributes is used by the preprocessor, which
│ │ │ -supports file inclusion, macros, and conditional compilation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="1764243954-1">(</span><span class="s">&quot;SomeFile.hrl&quot;</span><span class="p" data-group-id="1764243954-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1764243954-2">(</span><span class="n">Macro</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="1764243954-2">)</span><span class="p">.</span></code></pre><p>Read more in <a href="macros.html">Preprocessor</a>.</p><h3 id="setting-file-and-line" class="section-heading">
│ │ │ +supports file inclusion, macros, and conditional compilation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="8206920195-1">(</span><span class="s">&quot;SomeFile.hrl&quot;</span><span class="p" data-group-id="8206920195-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="8206920195-2">(</span><span class="n">Macro</span><span class="p">,</span><span class="w"> </span><span class="n">Replacement</span><span class="p" data-group-id="8206920195-2">)</span><span class="p">.</span></code></pre><p>Read more in <a href="macros.html">Preprocessor</a>.</p><h3 id="setting-file-and-line" class="section-heading">
│ │ │    <a href="#setting-file-and-line" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Setting File and Line</span>
│ │ │  </h3>
│ │ │  <p>The same syntax as for module attributes is used for changing the pre-defined
│ │ │ -macros <code class="inline">?FILE</code> and <code class="inline">?LINE</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">file</span><span class="p" data-group-id="1192412068-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">Line</span><span class="p" data-group-id="1192412068-1">)</span><span class="p">.</span></code></pre><p>This attribute is used by tools, such as Yecc, to inform the compiler that the
│ │ │ +macros <code class="inline">?FILE</code> and <code class="inline">?LINE</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">file</span><span class="p" data-group-id="1641754123-1">(</span><span class="n">File</span><span class="p">,</span><span class="w"> </span><span class="n">Line</span><span class="p" data-group-id="1641754123-1">)</span><span class="p">.</span></code></pre><p>This attribute is used by tools, such as Yecc, to inform the compiler that the
│ │ │  source program is generated by another tool. It also indicates the
│ │ │  correspondence of source files to lines of the original user-written file, from
│ │ │  which the source program is produced.</p><h3 id="types-and-function-specifications" class="section-heading">
│ │ │    <a href="#types-and-function-specifications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Types and function specifications</span>
│ │ │  </h3>
│ │ │  <p>A similar syntax as for module attributes is used for specifying types and
│ │ │ -function specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_type</span><span class="p" data-group-id="4737658937-1">(</span><span class="p" data-group-id="4737658937-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="4737658937-2">(</span><span class="p" data-group-id="4737658937-2">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="4737658937-3">(</span><span class="p" data-group-id="4737658937-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">my_function</span><span class="p" data-group-id="4737658937-4">(</span><span class="nf">integer</span><span class="p" data-group-id="4737658937-5">(</span><span class="p" data-group-id="4737658937-5">)</span><span class="p" data-group-id="4737658937-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="4737658937-6">(</span><span class="p" data-group-id="4737658937-6">)</span><span class="p">.</span></code></pre><p>Read more in <a href="typespec.html">Types and Function specifications</a>.</p><p>The description is based on
│ │ │ +function specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_type</span><span class="p" data-group-id="6110803575-1">(</span><span class="p" data-group-id="6110803575-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="6110803575-2">(</span><span class="p" data-group-id="6110803575-2">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="6110803575-3">(</span><span class="p" data-group-id="6110803575-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">my_function</span><span class="p" data-group-id="6110803575-4">(</span><span class="nf">integer</span><span class="p" data-group-id="6110803575-5">(</span><span class="p" data-group-id="6110803575-5">)</span><span class="p" data-group-id="6110803575-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="6110803575-6">(</span><span class="p" data-group-id="6110803575-6">)</span><span class="p">.</span></code></pre><p>Read more in <a href="typespec.html">Types and Function specifications</a>.</p><p>The description is based on
│ │ │  <a href="http://www.erlang.org/eeps/eep-0008.html">EEP8 - Types and function specifications</a>,
│ │ │  which is not to be further updated.</p><h3 id="documentation-attributes" class="section-heading">
│ │ │    <a href="#documentation-attributes" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Documentation attributes</span>
│ │ │  </h3>
│ │ │  <p>The module attribute <code class="inline">-doc(Documentation)</code> is used to provide user documentation
│ │ │ -for a function/type/callback:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="8769434884-1">(</span><span class="s">&quot;Example documentation&quot;</span><span class="p" data-group-id="8769434884-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">example</span><span class="p" data-group-id="8769434884-2">(</span><span class="p" data-group-id="8769434884-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The attribute should be placed just before the entity it documents.The
│ │ │ +for a function/type/callback:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="0733268259-1">(</span><span class="s">&quot;Example documentation&quot;</span><span class="p" data-group-id="0733268259-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">example</span><span class="p" data-group-id="0733268259-2">(</span><span class="p" data-group-id="0733268259-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The attribute should be placed just before the entity it documents.The
│ │ │  parenthesis are optional around <code class="inline">Documentation</code>. The allowed values for
│ │ │  <code class="inline">Documentation</code> are:</p><ul><li><p><strong><a href="data_types.html#string">literal string</a> or
│ │ │  <a href="expressions.html#unicode-segments">utf-8 encoded binary string</a></strong> - The string
│ │ │  documenting the entity. Any literal string is allowed, so both
│ │ │  <a href="data_types.html#tqstring">triple quoted strings</a> and
│ │ │  <a href="data_types.html#sigil">sigils</a> that translate to literal strings can be used.
│ │ │ -The following examples are equivalent:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="7864150972-1">(</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="p" data-group-id="7864150972-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="7864150972-2">(</span><span class="p" data-group-id="7864150972-3">&lt;&lt;</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="7864150972-3">&gt;&gt;</span><span class="p" data-group-id="7864150972-2">)</span><span class="p">.</span><span class="w">
│ │ │ +The following examples are equivalent:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="6883249647-1">(</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="p" data-group-id="6883249647-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">doc</span><span class="p" data-group-id="6883249647-2">(</span><span class="p" data-group-id="6883249647-3">&lt;&lt;</span><span class="s">&quot;Example \&quot;docs\&quot;&quot;</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="6883249647-3">&gt;&gt;</span><span class="p" data-group-id="6883249647-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">~S/Example &quot;docs&quot;/</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="s">&quot;
│ │ │     Example &quot;</span><span class="ss">docs</span><span class="s">&quot;
│ │ │     &quot;</span><span class="s">&quot;&quot;</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="na">doc</span><span class="w"> </span><span class="s">~B|Example &quot;docs&quot;|</span><span class="p">.</span></code></pre><p>For clarity it is recommended to use either normal <code class="inline">&quot;strings&quot;</code> or triple
│ │ │  quoted strings for documentation attributes.</p></li><li><p><strong><code class="inline">{file,</code> <a href="../../lib/kernel-10.2.7.2/doc/html/file.html#t:name/0"><code class="inline">file:name/0</code></a> <code class="inline">}</code></strong> - Read the contents of filename and use
│ │ │  that as the documentation string.</p></li><li><p><strong><code class="inline">false</code></strong> - Set the current entity as hidden, that is, it should not be
│ │ │ @@ -253,15 +253,15 @@
│ │ │    <a href="#the-feature-directive" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">The feature directive</span>
│ │ │  </h2>
│ │ │  <p>While not a module attribute, but rather a directive (since it might affect
│ │ │  syntax), there is the <code class="inline">-feature(..)</code> directive used for enabling and disabling
│ │ │ -<a href="../../doc/system/features.html#features">features</a>.</p><p>The syntax is similar to that of an attribute, but has two arguments:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">feature</span><span class="p" data-group-id="0688229864-1">(</span><span class="n">FeatureName</span><span class="p">,</span><span class="w"> </span><span class="ss">enable</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">disable</span><span class="p" data-group-id="0688229864-1">)</span><span class="p">.</span></code></pre><p>Note that the <a href="macros.html#feature-directive">feature directive</a> can only appear
│ │ │ +<a href="../../doc/system/features.html#features">features</a>.</p><p>The syntax is similar to that of an attribute, but has two arguments:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">feature</span><span class="p" data-group-id="1967549628-1">(</span><span class="n">FeatureName</span><span class="p">,</span><span class="w"> </span><span class="ss">enable</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">disable</span><span class="p" data-group-id="1967549628-1">)</span><span class="p">.</span></code></pre><p>Note that the <a href="macros.html#feature-directive">feature directive</a> can only appear
│ │ │  in a prefix of the module.</p><h2 id="comments" class="section-heading">
│ │ │    <a href="#comments" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Comments</span>
│ │ │  </h2>
│ │ │  <p>Comments can be placed anywhere in a module except within strings and
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/nif.html
│ │ │ @@ -133,26 +133,26 @@
│ │ │    <span class="text">Erlang Program</span>
│ │ │  </h2>
│ │ │  <p>Even if all functions of a module are NIFs, an Erlang module is still needed for
│ │ │  two reasons:</p><ul><li>The NIF library must be explicitly loaded by Erlang code in the same module.</li><li>All NIFs of a module must have an Erlang implementation as well.</li></ul><p>Normally these are minimal stub implementations that throw an exception. But
│ │ │  they can also be used as fallback implementations for functions that do not have
│ │ │  native implementations on some architectures.</p><p>NIF libraries are loaded by calling <a href="../../erts-15.2.7.3/doc/html/erlang.html#load_nif/2"><code class="inline">erlang:load_nif/2</code></a>, with the name of the
│ │ │  shared library as argument. The second argument can be any term that will be
│ │ │ -passed on to the library and used for initialization:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9521862652-1">(</span><span class="ss">complex6</span><span class="p" data-group-id="9521862652-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9521862652-2">(</span><span class="p" data-group-id="9521862652-3">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9521862652-3">]</span><span class="p" data-group-id="9521862652-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">nifs</span><span class="p" data-group-id="9521862652-4">(</span><span class="p" data-group-id="9521862652-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9521862652-5">]</span><span class="p" data-group-id="9521862652-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="9521862652-6">(</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9521862652-6">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="9521862652-7">(</span><span class="p" data-group-id="9521862652-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="9521862652-8">(</span><span class="s">&quot;./complex6_nif&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="9521862652-8">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="9521862652-9">(</span><span class="p">_</span><span class="n">X</span><span class="p" data-group-id="9521862652-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="9521862652-10">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="9521862652-10">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">bar</span><span class="p" data-group-id="9521862652-11">(</span><span class="p">_</span><span class="n">Y</span><span class="p" data-group-id="9521862652-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="9521862652-12">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="9521862652-12">)</span><span class="p">.</span></code></pre><p>Here, the directive <code class="inline">on_load</code> is used to get function <code class="inline">init</code> to be automatically
│ │ │ +passed on to the library and used for initialization:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9983046811-1">(</span><span class="ss">complex6</span><span class="p" data-group-id="9983046811-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9983046811-2">(</span><span class="p" data-group-id="9983046811-3">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9983046811-3">]</span><span class="p" data-group-id="9983046811-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">nifs</span><span class="p" data-group-id="9983046811-4">(</span><span class="p" data-group-id="9983046811-5">[</span><span class="ss">foo</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">bar</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9983046811-5">]</span><span class="p" data-group-id="9983046811-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="9983046811-6">(</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9983046811-6">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="9983046811-7">(</span><span class="p" data-group-id="9983046811-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ok</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="9983046811-8">(</span><span class="s">&quot;./complex6_nif&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="9983046811-8">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="9983046811-9">(</span><span class="p">_</span><span class="n">X</span><span class="p" data-group-id="9983046811-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="9983046811-10">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="9983046811-10">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">bar</span><span class="p" data-group-id="9983046811-11">(</span><span class="p">_</span><span class="n">Y</span><span class="p" data-group-id="9983046811-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="9983046811-12">(</span><span class="ss">nif_library_not_loaded</span><span class="p" data-group-id="9983046811-12">)</span><span class="p">.</span></code></pre><p>Here, the directive <code class="inline">on_load</code> is used to get function <code class="inline">init</code> to be automatically
│ │ │  called when the module is loaded. If <code class="inline">init</code> returns anything other than <code class="inline">ok</code>,
│ │ │  such when the loading of the NIF library fails in this example, the module is
│ │ │  unloaded and calls to functions within it, fail.</p><p>Loading the NIF library overrides the stub implementations and cause calls to
│ │ │  <code class="inline">foo</code> and <code class="inline">bar</code> to be dispatched to the NIF implementations instead.</p><h2 id="nif-library-code" class="section-heading">
│ │ │    <a href="#nif-library-code" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -209,23 +209,23 @@
│ │ │    <a href="#running-the-example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Running the Example</span>
│ │ │  </h2>
│ │ │  <p><em>Step 1.</em> Compile the C code:</p><pre><code class="text">unix&gt; gcc -o complex6_nif.so -fpic -shared complex.c complex6_nif.c
│ │ │  windows&gt; cl -LD -MD -Fe complex6_nif.dll complex.c complex6_nif.c</code></pre><p><em>Step 2:</em> Start Erlang and compile the Erlang code:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="ss">erl</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="w"> </span><span class="n">R13B04</span><span class="w"> </span><span class="p" data-group-id="5823968951-1">(</span><span class="ss">erts</span><span class="o">-</span><span class="mf">5.7</span><span class="p">.</span><span class="mi">5</span><span class="p" data-group-id="5823968951-1">)</span><span class="w"> </span><span class="p" data-group-id="5823968951-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="5823968951-2">]</span><span class="w"> </span><span class="p" data-group-id="5823968951-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="5823968951-3">]</span><span class="w"> </span><span class="p" data-group-id="5823968951-4">[</span><span class="nc">rq</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="5823968951-4">]</span><span class="w"> </span><span class="p" data-group-id="5823968951-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="5823968951-5">]</span><span class="w"> </span><span class="p" data-group-id="5823968951-6">[</span><span class="ss">kernel</span><span class="o">-</span><span class="nc">poll</span><span class="p">:</span><span class="ss">false</span><span class="p" data-group-id="5823968951-6">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="w"> </span><span class="n">R13B04</span><span class="w"> </span><span class="p" data-group-id="2122503699-1">(</span><span class="ss">erts</span><span class="o">-</span><span class="mf">5.7</span><span class="p">.</span><span class="mi">5</span><span class="p" data-group-id="2122503699-1">)</span><span class="w"> </span><span class="p" data-group-id="2122503699-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="2122503699-2">]</span><span class="w"> </span><span class="p" data-group-id="2122503699-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">4</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="2122503699-3">]</span><span class="w"> </span><span class="p" data-group-id="2122503699-4">[</span><span class="nc">rq</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="2122503699-4">]</span><span class="w"> </span><span class="p" data-group-id="2122503699-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">0</span><span class="p" data-group-id="2122503699-5">]</span><span class="w"> </span><span class="p" data-group-id="2122503699-6">[</span><span class="ss">kernel</span><span class="o">-</span><span class="nc">poll</span><span class="p">:</span><span class="ss">false</span><span class="p" data-group-id="2122503699-6">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">7.5</span><span class="w">  </span><span class="p" data-group-id="5823968951-7">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="5823968951-7">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="5823968951-8">(</span><span class="ss">complex6</span><span class="p" data-group-id="5823968951-8">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5823968951-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex6</span><span class="p" data-group-id="5823968951-9">}</span></code></pre><p><em>Step 3:</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="8575329287-1">(</span><span class="mi">3</span><span class="p" data-group-id="8575329287-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V5</span><span class="p">.</span><span class="mf">7.5</span><span class="w">  </span><span class="p" data-group-id="2122503699-7">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="2122503699-7">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="2122503699-8">(</span><span class="ss">complex6</span><span class="p" data-group-id="2122503699-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2122503699-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">complex6</span><span class="p" data-group-id="2122503699-9">}</span></code></pre><p><em>Step 3:</em> Run the example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="1177694750-1">(</span><span class="mi">3</span><span class="p" data-group-id="1177694750-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="8575329287-2">(</span><span class="mi">5</span><span class="p" data-group-id="8575329287-2">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">bar</span><span class="p" data-group-id="1177694750-2">(</span><span class="mi">5</span><span class="p" data-group-id="1177694750-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="8575329287-3">(</span><span class="s">&quot;not an integer&quot;</span><span class="p" data-group-id="8575329287-3">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">complex6</span><span class="p">:</span><span class="nf">foo</span><span class="p" data-group-id="1177694750-3">(</span><span class="s">&quot;not an integer&quot;</span><span class="p" data-group-id="1177694750-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: bad argument
│ │ │       in function  complex6:foo/1
│ │ │          called as comlpex6:foo(&quot;not an integer&quot;)</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/opaques.html
│ │ │ @@ -122,24 +122,24 @@
│ │ │    <span class="text">Opaque Type Aliases</span>
│ │ │  </h2>
│ │ │  <p>The main use case for opacity in Erlang is to hide the implementation of a data
│ │ │  type, enabling evolving the API while minimizing the risk of breaking consumers.
│ │ │  The runtime does not check opacity. Dialyzer provides some opacity-checking, but
│ │ │  the rest is up to convention.</p><p>This document explains what Erlang opacity is (and the trade-offs involved) via
│ │ │  the example of the <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html#t:set/0"><code class="inline">sets:set()</code></a> data type. This type <em>was</em>
│ │ │ -defined in the <code class="inline">sets</code> module like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="4264393446-1">(</span><span class="n">Element</span><span class="p" data-group-id="4264393446-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="4264393446-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="4264393446-3">(</span><span class="n">Element</span><span class="p" data-group-id="4264393446-3">)</span><span class="p" data-group-id="4264393446-2">}</span><span class="p">.</span></code></pre><p>OTP 24 changed the definition to the following in
│ │ │ -<a href="https://github.com/erlang/otp/commit/e66941e8d7c47b973dff94c0308ea85a6be1958e">this commit</a>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="3679817903-1">(</span><span class="n">Element</span><span class="p" data-group-id="3679817903-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="3679817903-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="3679817903-3">(</span><span class="n">Element</span><span class="p" data-group-id="3679817903-3">)</span><span class="p" data-group-id="3679817903-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="3679817903-4">#{</span><span class="n">Element</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VALUE</span><span class="p" data-group-id="3679817903-4">}</span><span class="p">.</span></code></pre><p>And this change was safer and more backwards-compatible than if the type had
│ │ │ +defined in the <code class="inline">sets</code> module like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="0256217605-1">(</span><span class="n">Element</span><span class="p" data-group-id="0256217605-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="0256217605-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="0256217605-3">(</span><span class="n">Element</span><span class="p" data-group-id="0256217605-3">)</span><span class="p" data-group-id="0256217605-2">}</span><span class="p">.</span></code></pre><p>OTP 24 changed the definition to the following in
│ │ │ +<a href="https://github.com/erlang/otp/commit/e66941e8d7c47b973dff94c0308ea85a6be1958e">this commit</a>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">set</span><span class="p" data-group-id="3987579267-1">(</span><span class="n">Element</span><span class="p" data-group-id="3987579267-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">set</span><span class="p" data-group-id="3987579267-2">{</span><span class="ss">segs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">segs</span><span class="p" data-group-id="3987579267-3">(</span><span class="n">Element</span><span class="p" data-group-id="3987579267-3">)</span><span class="p" data-group-id="3987579267-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="3987579267-4">#{</span><span class="n">Element</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="o">?</span><span class="n">VALUE</span><span class="p" data-group-id="3987579267-4">}</span><span class="p">.</span></code></pre><p>And this change was safer and more backwards-compatible than if the type had
│ │ │  been defined with <code class="inline">-type</code> instead of <code class="inline">-opaque</code>. Here is why: when a module
│ │ │  defines an <code class="inline">-opaque</code>, the contract is that only the defining module should rely
│ │ │  on the definition of the type: no other modules should rely on the definition.</p><p>This means that code that pattern-matched on <code class="inline">set</code> as a record/tuple technically
│ │ │  broke the contract, and opted in to being potentially broken when the definition
│ │ │  of <code class="inline">set()</code> changed. Before OTP 24, this code printed <code class="inline">ok</code>. In OTP 24 it may
│ │ │ -error:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="6510365849-1">(</span><span class="p" data-group-id="6510365849-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="n">Set</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_tuple</span><span class="p" data-group-id="6510365849-2">(</span><span class="n">Set</span><span class="p" data-group-id="6510365849-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6510365849-3">(</span><span class="s">&quot;ok&quot;</span><span class="p" data-group-id="6510365849-3">)</span><span class="w">
│ │ │ +error:</p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">sets</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="8305353724-1">(</span><span class="p" data-group-id="8305353724-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="n">Set</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_tuple</span><span class="p" data-group-id="8305353724-2">(</span><span class="n">Set</span><span class="p" data-group-id="8305353724-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8305353724-3">(</span><span class="s">&quot;ok&quot;</span><span class="p" data-group-id="8305353724-3">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span></code></pre><p><strong>When working with an opaque defined in another module, here are some
│ │ │  recommendations:</strong></p><ul><li>Don't examine the underlying type using pattern-matching, guards, or functions
│ │ │  that reveal the type, such as <a href="../../erts-15.2.7.3/doc/html/erlang.html#tuple_size/1"><code class="inline">tuple_size/1</code></a> .</li><li>Instead, use functions provided by the module for working with the type. For
│ │ │  example, <code class="inline">sets</code> module provides <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html#new/0"><code class="inline">sets:new/0</code></a>, <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html#add_element/2"><code class="inline">sets:add_element/2</code></a>,
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html#is_element/2"><code class="inline">sets:is_element/2</code></a>, and so on.</li><li><p><a href="../../lib/stdlib-6.2.2.2/doc/html/sets.html#t:set/1"><code class="inline">sets:set(a)</code></a> is a subtype of <code class="inline">sets:set(a | b)</code> and not the
│ │ │  other way around. Generally, you can rely on the property that <code class="inline">the_opaque(T)</code>
│ │ │  is a subtype of <code class="inline">the_opaque(U)</code> when T is a subtype of U.</p></li></ul><p><strong>When defining your own opaques, here are some recommendations:</strong></p><ul><li>Since consumers are expected to not rely on the definition of the opaque type,
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/otp-patch-apply.html
│ │ │ @@ -201,15 +201,15 @@
│ │ │    </a>
│ │ │    <span class="text">Sanity check</span>
│ │ │  </h2>
│ │ │  <p>The application dependencies can be checked using the Erlang shell.
│ │ │  Application dependencies are verified among installed applications by
│ │ │  <code class="inline">otp_patch_apply</code>, but these are not necessarily those actually loaded.
│ │ │  By calling <code class="inline">system_information:sanity_check()</code> one can validate
│ │ │ -dependencies among applications actually loaded.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">system_information</span><span class="p">:</span><span class="nf">sanity_check</span><span class="p" data-group-id="7153127420-1">(</span><span class="p" data-group-id="7153127420-1">)</span><span class="p">.</span><span class="w">
│ │ │ +dependencies among applications actually loaded.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">system_information</span><span class="p">:</span><span class="nf">sanity_check</span><span class="p" data-group-id="0274230024-1">(</span><span class="p" data-group-id="0274230024-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>Please take a look at the reference of <a href="../../lib/runtime_tools-2.1.1/doc/html/system_information.html#sanity_check/0" title="">sanity_check()</a> for more
│ │ │  information.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/patterns.html
│ │ │ @@ -128,18 +128,18 @@
│ │ │  succeeds, any unbound variables in the pattern become bound. If the matching
│ │ │  fails, an exception is raised.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** 1:1: variable &#39;X&#39; is unbound **</span><span class="gp unselectable">
│ │ │  2&gt; </span><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">2</span><span class="gp unselectable">
│ │ │  3&gt; </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="p" data-group-id="7029382133-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7029382133-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7029382133-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="7029382133-2">}</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="p" data-group-id="4667511367-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4667511367-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4667511367-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="4667511367-2">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no match of right hand side value {1,2}</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="p" data-group-id="7029382133-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="7029382133-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7029382133-4">{</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7029382133-4">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7029382133-5">{</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7029382133-5">}</span><span class="gp unselectable">
│ │ │ +5&gt; </span><span class="p" data-group-id="4667511367-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4667511367-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4667511367-4">{</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="4667511367-4">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4667511367-5">{</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4667511367-5">}</span><span class="gp unselectable">
│ │ │  6&gt; </span><span class="n">Y</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/prog_ex_records.html
│ │ │ @@ -122,105 +122,105 @@
│ │ │    <span class="text">Records and Tuples</span>
│ │ │  </h2>
│ │ │  <p>The main advantage of using records rather than tuples is that fields in a
│ │ │  record are accessed by name, whereas fields in a tuple are accessed by position.
│ │ │  To illustrate these differences, suppose that you want to represent a person
│ │ │  with the tuple <code class="inline">{Name, Address, Phone}</code>.</p><p>To write functions that manipulate this data, remember the following:</p><ul><li>The <code class="inline">Name</code> field is the first element of the tuple.</li><li>The <code class="inline">Address</code> field is the second element.</li><li>The <code class="inline">Phone</code> field is the third element.</li></ul><p>For example, to extract data from a variable <code class="inline">P</code> that contains such a tuple, you
│ │ │  can write the following code and then use pattern matching to extract the
│ │ │ -relevant fields:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="7368839070-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="7368839070-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="7368839070-2">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="7368839070-2">)</span><span class="p">,</span><span class="w">
│ │ │ +relevant fields:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="3014149004-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="3014149004-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">element</span><span class="p" data-group-id="3014149004-2">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p" data-group-id="3014149004-2">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Such code is difficult to read and understand, and errors occur if the numbering
│ │ │  of the elements in the tuple is wrong. If the data representation of the fields
│ │ │  is changed, by re-ordering, adding, or removing fields, all references to the
│ │ │  person tuple must be checked and possibly modified.</p><p>Records allow references to the fields by name, instead of by position. In the
│ │ │ -following example, a record instead of a tuple is used to store the data:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7124451091-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7124451091-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="7124451091-2">}</span><span class="p" data-group-id="7124451091-1">)</span><span class="p">.</span></code></pre><p>This enables references to the fields of the record by name. For example, if <code class="inline">P</code>
│ │ │ +following example, a record instead of a tuple is used to store the data:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6517468050-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6517468050-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="6517468050-2">}</span><span class="p" data-group-id="6517468050-1">)</span><span class="p">.</span></code></pre><p>This enables references to the fields of the record by name. For example, if <code class="inline">P</code>
│ │ │  is a variable whose value is a <code class="inline">person</code> record, the following code access the
│ │ │  name and address fields of the records:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="n">Address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">address</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Internally, records are represented using tagged tuples:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0186212246-1">{</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p" data-group-id="0186212246-1">}</span></code></pre><h2 id="defining-a-record" class="section-heading">
│ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Internally, records are represented using tagged tuples:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2175871101-1">{</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p" data-group-id="2175871101-1">}</span></code></pre><h2 id="defining-a-record" class="section-heading">
│ │ │    <a href="#defining-a-record" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Defining a Record</span>
│ │ │  </h2>
│ │ │  <p>This following definition of a <code class="inline">person</code> is used in several examples in this
│ │ │  section. Three fields are included, <code class="inline">name</code>, <code class="inline">phone</code>, and <code class="inline">address</code>. The default
│ │ │  values for <code class="inline">name</code> and <code class="inline">phone</code> is &quot;&quot; and [], respectively. The default value for
│ │ │  <code class="inline">address</code> is the atom <code class="inline">undefined</code>, since no default value is supplied for this
│ │ │ -field:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9442296331-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9442296331-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9442296331-3">[</span><span class="p" data-group-id="9442296331-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="9442296331-2">}</span><span class="p" data-group-id="9442296331-1">)</span><span class="p">.</span></code></pre><p>The record must be defined in the shell to enable use of the record syntax in
│ │ │ -the examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">rd</span><span class="p" data-group-id="2149388993-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2149388993-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2149388993-3">[</span><span class="p" data-group-id="2149388993-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="2149388993-2">}</span><span class="p" data-group-id="2149388993-1">)</span><span class="p">.</span><span class="w">
│ │ │ +field:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8475479484-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8475479484-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8475479484-3">[</span><span class="p" data-group-id="8475479484-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="8475479484-2">}</span><span class="p" data-group-id="8475479484-1">)</span><span class="p">.</span></code></pre><p>The record must be defined in the shell to enable use of the record syntax in
│ │ │ +the examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">rd</span><span class="p" data-group-id="2924745541-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2924745541-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2924745541-3">[</span><span class="p" data-group-id="2924745541-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="2924745541-2">}</span><span class="p" data-group-id="2924745541-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">person</span></code></pre><p>This is because record definitions are only available at compile time, not at
│ │ │  runtime. For details on records in the shell, see the <a href="../../lib/stdlib-6.2.2.2/doc/html/shell.html"><code class="inline">shell</code></a> manual page in
│ │ │  STDLIB.</p><h2 id="creating-a-record" class="section-heading">
│ │ │    <a href="#creating-a-record" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Creating a Record</span>
│ │ │  </h2>
│ │ │ -<p>A new <code class="inline">person</code> record is created as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="8826411784-1">{</span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="8826411784-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8826411784-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="8826411784-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="8826411784-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8826411784-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8826411784-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="8826411784-3">}</span></code></pre><p>As the <code class="inline">address</code> field was omitted, its default value is used.</p><p>From Erlang 5.1/OTP R8B, a value to all fields in a record can be set with the
│ │ │ -special field <code class="inline">_</code>. <code class="inline">_</code> means &quot;all fields not explicitly specified&quot;.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2967096641-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="2967096641-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2967096641-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="2967096641-2">}</span></code></pre><p>It is primarily intended to be used in <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a> and
│ │ │ +<p>A new <code class="inline">person</code> record is created as follows:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3841912089-1">{</span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="3841912089-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3841912089-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="3841912089-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3841912089-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3841912089-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3841912089-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="3841912089-3">}</span></code></pre><p>As the <code class="inline">address</code> field was omitted, its default value is used.</p><p>From Erlang 5.1/OTP R8B, a value to all fields in a record can be set with the
│ │ │ +special field <code class="inline">_</code>. <code class="inline">_</code> means &quot;all fields not explicitly specified&quot;.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0625562926-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="0625562926-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0625562926-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Jakob&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="0625562926-2">}</span></code></pre><p>It is primarily intended to be used in <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a> and
│ │ │  <a href="../../lib/mnesia-4.23.5/doc/html/mnesia.html#match_object/3"><code class="inline">mnesia:match_object/3</code></a>, to set record fields to the atom <code class="inline">'_'</code>. (This is a
│ │ │  wildcard in <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a>.)</p><h2 id="accessing-a-record-field" class="section-heading">
│ │ │    <a href="#accessing-a-record-field" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Accessing a Record Field</span>
│ │ │  </h2>
│ │ │ -<p>The following example shows how to access a record field:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2569362055-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2569362055-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2569362055-2">]</span><span class="p" data-group-id="2569362055-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2569362055-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2569362055-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2569362055-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="2569362055-3">}</span><span class="gp unselectable">
│ │ │ +<p>The following example shows how to access a record field:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9976760897-1">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9976760897-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9976760897-2">]</span><span class="p" data-group-id="9976760897-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9976760897-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9976760897-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9976760897-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">undefined</span><span class="p" data-group-id="9976760897-3">}</span><span class="gp unselectable">
│ │ │  &gt; </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;Joe&quot;</span></code></pre><h2 id="updating-a-record" class="section-heading">
│ │ │    <a href="#updating-a-record" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Updating a Record</span>
│ │ │  </h2>
│ │ │ -<p>The following example shows how to update a record:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="8292699863-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="8292699863-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8292699863-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="8292699863-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="8292699863-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8292699863-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8292699863-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="8292699863-3">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P1</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="8292699863-5">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="8292699863-5">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="8292699863-6">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8292699863-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8292699863-7">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="8292699863-6">}</span></code></pre><h2 id="type-testing" class="section-heading">
│ │ │ +<p>The following example shows how to update a record:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1260023601-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="1260023601-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1260023601-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="1260023601-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1260023601-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1260023601-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1260023601-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="1260023601-3">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">P2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P1</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1260023601-5">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p" data-group-id="1260023601-5">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1260023601-6">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1260023601-7">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1260023601-7">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="1260023601-6">}</span></code></pre><h2 id="type-testing" class="section-heading">
│ │ │    <a href="#type-testing" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Type Testing</span>
│ │ │  </h2>
│ │ │  <p>The following example shows that the guard succeeds if <code class="inline">P</code> is record of type
│ │ │ -<code class="inline">person</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="5190004122-1">(</span><span class="n">P</span><span class="p" data-group-id="5190004122-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="5190004122-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="5190004122-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">a_person</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">foo</span><span class="p" data-group-id="5190004122-3">(</span><span class="p">_</span><span class="p" data-group-id="5190004122-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">not_a_person</span><span class="p">.</span></code></pre><h2 id="pattern-matching" class="section-heading">
│ │ │ +<code class="inline">person</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foo</span><span class="p" data-group-id="3216460343-1">(</span><span class="n">P</span><span class="p" data-group-id="3216460343-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="3216460343-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="3216460343-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">a_person</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">foo</span><span class="p" data-group-id="3216460343-3">(</span><span class="p">_</span><span class="p" data-group-id="3216460343-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">not_a_person</span><span class="p">.</span></code></pre><h2 id="pattern-matching" class="section-heading">
│ │ │    <a href="#pattern-matching" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Pattern Matching</span>
│ │ │  </h2>
│ │ │  <p>Matching can be used in combination with records, as shown in the following
│ │ │ -example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9014541803-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="9014541803-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9014541803-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="9014541803-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9014541803-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9014541803-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="9014541803-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="9014541803-3">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9014541803-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="9014541803-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P3</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">.</span><span class="w">
│ │ │ +example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">P3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6851495916-1">{</span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="p" data-group-id="6851495916-2">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="6851495916-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="o">=</span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="6851495916-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6851495916-3">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6851495916-4">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="6851495916-4">]</span><span class="p">,</span><span class="ss">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;A street&quot;</span><span class="p" data-group-id="6851495916-3">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6851495916-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="6851495916-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P3</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;Joe&quot;</span></code></pre><p>The following function takes a list of <code class="inline">person</code> records and searches for the
│ │ │ -phone number of a person with a particular name:</p><pre><code class="makeup erlang" translate="no"><span class="nf">find_phone</span><span class="p" data-group-id="4526497555-1">(</span><span class="p" data-group-id="4526497555-2">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4526497555-3">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="n">Phone</span><span class="p" data-group-id="4526497555-3">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="4526497555-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4526497555-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4526497555-4">{</span><span class="ss">found</span><span class="p">,</span><span class="w">  </span><span class="n">Phone</span><span class="p" data-group-id="4526497555-4">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">find_phone</span><span class="p" data-group-id="4526497555-5">(</span><span class="p" data-group-id="4526497555-6">[</span><span class="p">_</span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="4526497555-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4526497555-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">find_phone</span><span class="p" data-group-id="4526497555-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4526497555-7">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">find_phone</span><span class="p" data-group-id="4526497555-8">(</span><span class="p" data-group-id="4526497555-9">[</span><span class="p" data-group-id="4526497555-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4526497555-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +phone number of a person with a particular name:</p><pre><code class="makeup erlang" translate="no"><span class="nf">find_phone</span><span class="p" data-group-id="3205670657-1">(</span><span class="p" data-group-id="3205670657-2">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3205670657-3">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="n">Phone</span><span class="p" data-group-id="3205670657-3">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="3205670657-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3205670657-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3205670657-4">{</span><span class="ss">found</span><span class="p">,</span><span class="w">  </span><span class="n">Phone</span><span class="p" data-group-id="3205670657-4">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">find_phone</span><span class="p" data-group-id="3205670657-5">(</span><span class="p" data-group-id="3205670657-6">[</span><span class="p">_</span><span class="p">|</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="3205670657-6">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3205670657-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">find_phone</span><span class="p" data-group-id="3205670657-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3205670657-7">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">find_phone</span><span class="p" data-group-id="3205670657-8">(</span><span class="p" data-group-id="3205670657-9">[</span><span class="p" data-group-id="3205670657-9">]</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3205670657-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">not_found</span><span class="p">.</span></code></pre><p>The fields referred to in the pattern can be given in any order.</p><h2 id="nested-records" class="section-heading">
│ │ │    <a href="#nested-records" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Nested Records</span>
│ │ │  </h2>
│ │ │  <p>The value of a field in a record can be an instance of a record. Retrieval of
│ │ │  nested data can be done stepwise, or in a single step, as shown in the following
│ │ │ -example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9812636889-1">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9812636889-2">{</span><span class="ss">first</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">last</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Ericsson&quot;</span><span class="p" data-group-id="9812636889-2">}</span><span class="p" data-group-id="9812636889-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9812636889-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9812636889-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="9812636889-5">{</span><span class="p" data-group-id="9812636889-5">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p" data-group-id="9812636889-4">}</span><span class="p" data-group-id="9812636889-3">)</span><span class="p">.</span><span class="w">
│ │ │ +example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5750380944-1">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5750380944-2">{</span><span class="ss">first</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">last</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Ericsson&quot;</span><span class="p" data-group-id="5750380944-2">}</span><span class="p" data-group-id="5750380944-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5750380944-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5750380944-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="5750380944-5">{</span><span class="p" data-group-id="5750380944-5">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p" data-group-id="5750380944-4">}</span><span class="p" data-group-id="5750380944-3">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">demo</span><span class="p" data-group-id="9812636889-6">(</span><span class="p" data-group-id="9812636889-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9812636889-7">{</span><span class="ss">name</span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="9812636889-8">{</span><span class="ss">first</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">last</span><span class="o">=</span><span class="s">&quot;Virding&quot;</span><span class="p" data-group-id="9812636889-8">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="mi">123</span><span class="p" data-group-id="9812636889-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="n">First</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9812636889-9">(</span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="9812636889-9">)</span><span class="o">#</span><span class="ss">name</span><span class="p">.</span><span class="ss">first</span><span class="p">.</span></code></pre><p>Here, <code class="inline">demo()</code> evaluates to <code class="inline">&quot;Robert&quot;</code>.</p><h2 id="a-longer-example" class="section-heading">
│ │ │ +</span><span class="nf">demo</span><span class="p" data-group-id="5750380944-6">(</span><span class="p" data-group-id="5750380944-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="n">P</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5750380944-7">{</span><span class="ss">name</span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">name</span><span class="p" data-group-id="5750380944-8">{</span><span class="ss">first</span><span class="o">=</span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="ss">last</span><span class="o">=</span><span class="s">&quot;Virding&quot;</span><span class="p" data-group-id="5750380944-8">}</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="o">=</span><span class="mi">123</span><span class="p" data-group-id="5750380944-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="n">First</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5750380944-9">(</span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="5750380944-9">)</span><span class="o">#</span><span class="ss">name</span><span class="p">.</span><span class="ss">first</span><span class="p">.</span></code></pre><p>Here, <code class="inline">demo()</code> evaluates to <code class="inline">&quot;Robert&quot;</code>.</p><h2 id="a-longer-example" class="section-heading">
│ │ │    <a href="#a-longer-example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">A Longer Example</span>
│ │ │  </h2>
│ │ │  <p>Comments are embedded in the following example:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% File: person.hrl</span><span class="w">
│ │ │  
│ │ │ @@ -230,48 +230,48 @@
│ │ │  </span><span class="c1">%%    name:  A string (default is undefined).</span><span class="w">
│ │ │  </span><span class="c1">%%    age:   An integer (default is undefined).</span><span class="w">
│ │ │  </span><span class="c1">%%    phone: A list of integers (default is []).</span><span class="w">
│ │ │  </span><span class="c1">%%    dict:  A dictionary containing various information</span><span class="w">
│ │ │  </span><span class="c1">%%           about the person.</span><span class="w">
│ │ │  </span><span class="c1">%%           A {Key, Value} list (default is the empty list).</span><span class="w">
│ │ │  </span><span class="c1">%%------------------------------------------------------------</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1952366731-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1952366731-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1952366731-3">[</span><span class="p" data-group-id="1952366731-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1952366731-4">[</span><span class="p" data-group-id="1952366731-4">]</span><span class="p" data-group-id="1952366731-2">}</span><span class="p" data-group-id="1952366731-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9624726972-1">(</span><span class="ss">person</span><span class="p" data-group-id="9624726972-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="9624726972-2">(</span><span class="s">&quot;person.hrl&quot;</span><span class="p" data-group-id="9624726972-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="9624726972-3">(</span><span class="ss">export_all</span><span class="p" data-group-id="9624726972-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% For test purposes only.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8269976087-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8269976087-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8269976087-3">[</span><span class="p" data-group-id="8269976087-3">]</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8269976087-4">[</span><span class="p" data-group-id="8269976087-4">]</span><span class="p" data-group-id="8269976087-2">}</span><span class="p" data-group-id="8269976087-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5826759550-1">(</span><span class="ss">person</span><span class="p" data-group-id="5826759550-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="5826759550-2">(</span><span class="s">&quot;person.hrl&quot;</span><span class="p" data-group-id="5826759550-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">compile</span><span class="p" data-group-id="5826759550-3">(</span><span class="ss">export_all</span><span class="p" data-group-id="5826759550-3">)</span><span class="p">.</span><span class="w"> </span><span class="c1">% For test purposes only.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% This creates an instance of a person.</span><span class="w">
│ │ │  </span><span class="c1">%%   Note: The phone number is not supplied so the</span><span class="w">
│ │ │  </span><span class="c1">%%         default value [] will be used.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="9624726972-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="9624726972-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9624726972-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ -           </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9624726972-6">[</span><span class="p" data-group-id="9624726972-7">{</span><span class="ss">computer_knowledge</span><span class="p">,</span><span class="w"> </span><span class="ss">excellent</span><span class="p" data-group-id="9624726972-7">}</span><span class="p">,</span><span class="w">
│ │ │ -                   </span><span class="p" data-group-id="9624726972-8">{</span><span class="ss">drinks</span><span class="p">,</span><span class="w"> </span><span class="ss">coke</span><span class="p" data-group-id="9624726972-8">}</span><span class="p" data-group-id="9624726972-6">]</span><span class="p" data-group-id="9624726972-5">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="5826759550-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="5826759550-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5826759550-5">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ +           </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5826759550-6">[</span><span class="p" data-group-id="5826759550-7">{</span><span class="ss">computer_knowledge</span><span class="p">,</span><span class="w"> </span><span class="ss">excellent</span><span class="p" data-group-id="5826759550-7">}</span><span class="p">,</span><span class="w">
│ │ │ +                   </span><span class="p" data-group-id="5826759550-8">{</span><span class="ss">drinks</span><span class="p">,</span><span class="w"> </span><span class="ss">coke</span><span class="p" data-group-id="5826759550-8">}</span><span class="p" data-group-id="5826759550-6">]</span><span class="p" data-group-id="5826759550-5">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% This demonstrates matching in arguments</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">print</span><span class="p" data-group-id="9624726972-9">(</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9624726972-10">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="9624726972-10">}</span><span class="p" data-group-id="9624726972-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9624726972-11">(</span><span class="s">&quot;Name: </span><span class="si">~s</span><span class="s">, Age: </span><span class="si">~w</span><span class="s">, Phone: </span><span class="si">~w</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="w">
│ │ │ -            </span><span class="s">&quot;Dictionary: </span><span class="si">~w</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9624726972-12">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="9624726972-12">]</span><span class="p" data-group-id="9624726972-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">print</span><span class="p" data-group-id="5826759550-9">(</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5826759550-10">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="ss">dict</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="5826759550-10">}</span><span class="p" data-group-id="5826759550-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5826759550-11">(</span><span class="s">&quot;Name: </span><span class="si">~s</span><span class="s">, Age: </span><span class="si">~w</span><span class="s">, Phone: </span><span class="si">~w</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="w">
│ │ │ +            </span><span class="s">&quot;Dictionary: </span><span class="si">~w</span><span class="s">.</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5826759550-12">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Age</span><span class="p">,</span><span class="w"> </span><span class="n">Phone</span><span class="p">,</span><span class="w"> </span><span class="n">Dict</span><span class="p" data-group-id="5826759550-12">]</span><span class="p" data-group-id="5826759550-11">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% Demonstrates type testing, selector, updating.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">birthday</span><span class="p" data-group-id="9624726972-13">(</span><span class="n">P</span><span class="p" data-group-id="9624726972-13">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="9624726972-14">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="9624726972-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9624726972-15">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="9624726972-15">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">birthday</span><span class="p" data-group-id="5826759550-13">(</span><span class="n">P</span><span class="p" data-group-id="5826759550-13">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="5826759550-14">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="5826759550-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5826759550-15">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="5826759550-15">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">register_two_hackers</span><span class="p" data-group-id="9624726972-16">(</span><span class="p" data-group-id="9624726972-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="n">Hacker1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="9624726972-17">(</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">29</span><span class="p" data-group-id="9624726972-17">)</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="n">OldHacker</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">birthday</span><span class="p" data-group-id="9624726972-18">(</span><span class="n">Hacker1</span><span class="p" data-group-id="9624726972-18">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">register_two_hackers</span><span class="p" data-group-id="5826759550-16">(</span><span class="p" data-group-id="5826759550-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="n">Hacker1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_hacker_without_phone</span><span class="p" data-group-id="5826759550-17">(</span><span class="s">&quot;Joe&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">29</span><span class="p" data-group-id="5826759550-17">)</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="n">OldHacker</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">birthday</span><span class="p" data-group-id="5826759550-18">(</span><span class="n">Hacker1</span><span class="p" data-group-id="5826759550-18">)</span><span class="p">,</span><span class="w">
│ │ │     </span><span class="c1">% The central_register_server should have</span><span class="w">
│ │ │     </span><span class="c1">% an interface function for this.</span><span class="w">
│ │ │ -   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9624726972-19">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w"> </span><span class="n">Hacker1</span><span class="p" data-group-id="9624726972-19">}</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="9624726972-20">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="n">OldHacker</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9624726972-21">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w">
│ │ │ -                              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9624726972-22">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9624726972-22">]</span><span class="p" data-group-id="9624726972-21">}</span><span class="p" data-group-id="9624726972-20">}</span><span class="p">.</span></code></pre>
│ │ │ +   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5826759550-19">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w"> </span><span class="n">Hacker1</span><span class="p" data-group-id="5826759550-19">}</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="ss">central_register_server</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="5826759550-20">{</span><span class="ss">register_person</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="n">OldHacker</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="5826759550-21">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;Robert&quot;</span><span class="p">,</span><span class="w">
│ │ │ +                              </span><span class="ss">phone</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5826759550-22">[</span><span class="mi">0</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5826759550-22">]</span><span class="p" data-group-id="5826759550-21">}</span><span class="p" data-group-id="5826759550-20">}</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="programming_examples.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/records_macros.html
│ │ │ @@ -124,40 +124,40 @@
│ │ │  </h2>
│ │ │  <p>To illustrate this, the messenger example from the previous section is divided
│ │ │  into the following five files:</p><ul><li><p><code class="inline">mess_config.hrl</code></p><p>Header file for configuration data</p></li><li><p><code class="inline">mess_interface.hrl</code></p><p>Interface definitions between the client and the messenger</p></li><li><p><code class="inline">user_interface.erl</code></p><p>Functions for the user interface</p></li><li><p><code class="inline">mess_client.erl</code></p><p>Functions for the client side of the messenger</p></li><li><p><code class="inline">mess_server.erl</code></p><p>Functions for the server side of the messenger</p></li></ul><p>While doing this, the message passing interface between the shell, the client,
│ │ │  and the server is cleaned up and is defined using <em>records</em>. Also, <em>macros</em> are
│ │ │  introduced:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_config.hrl----</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Configure the location of the server node,</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="8760774397-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="8760774397-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5679553055-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="5679553055-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%%----END FILE----</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_interface.hrl----</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Message interface between client and server and client shell for</span><span class="w">
│ │ │  </span><span class="c1">%%% messenger program</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%%Messages from Client to server received in server/1 function.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5099461185-1">(</span><span class="ss">logon</span><span class="p">,</span><span class="p" data-group-id="5099461185-2">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="p" data-group-id="5099461185-2">}</span><span class="p" data-group-id="5099461185-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5099461185-3">(</span><span class="ss">message</span><span class="p">,</span><span class="p" data-group-id="5099461185-4">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="5099461185-4">}</span><span class="p" data-group-id="5099461185-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1027065945-1">(</span><span class="ss">logon</span><span class="p">,</span><span class="p" data-group-id="1027065945-2">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="p" data-group-id="1027065945-2">}</span><span class="p" data-group-id="1027065945-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1027065945-3">(</span><span class="ss">message</span><span class="p">,</span><span class="p" data-group-id="1027065945-4">{</span><span class="ss">client_pid</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="1027065945-4">}</span><span class="p" data-group-id="1027065945-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%% {&#39;EXIT&#39;, ClientPid, Reason}  (client terminated or unreachable.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Messages from Server to Client, received in await_result/0 function</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5099461185-5">(</span><span class="ss">abort_client</span><span class="p">,</span><span class="p" data-group-id="5099461185-6">{</span><span class="ss">message</span><span class="p" data-group-id="5099461185-6">}</span><span class="p" data-group-id="5099461185-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1027065945-5">(</span><span class="ss">abort_client</span><span class="p">,</span><span class="p" data-group-id="1027065945-6">{</span><span class="ss">message</span><span class="p" data-group-id="1027065945-6">}</span><span class="p" data-group-id="1027065945-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%% Messages are: user_exists_at_other_node,</span><span class="w">
│ │ │  </span><span class="c1">%%%               you_are_not_logged_on</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5099461185-7">(</span><span class="ss">server_reply</span><span class="p">,</span><span class="p" data-group-id="5099461185-8">{</span><span class="ss">message</span><span class="p" data-group-id="5099461185-8">}</span><span class="p" data-group-id="5099461185-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1027065945-7">(</span><span class="ss">server_reply</span><span class="p">,</span><span class="p" data-group-id="1027065945-8">{</span><span class="ss">message</span><span class="p" data-group-id="1027065945-8">}</span><span class="p" data-group-id="1027065945-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%% Messages are: logged_on</span><span class="w">
│ │ │  </span><span class="c1">%%%               receiver_not_found</span><span class="w">
│ │ │  </span><span class="c1">%%%               sent  (Message has been sent (no guarantee)</span><span class="w">
│ │ │  </span><span class="c1">%%% Messages from Server to Client received in client/1 function</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5099461185-9">(</span><span class="ss">message_from</span><span class="p">,</span><span class="p" data-group-id="5099461185-10">{</span><span class="ss">from_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="5099461185-10">}</span><span class="p" data-group-id="5099461185-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1027065945-9">(</span><span class="ss">message_from</span><span class="p">,</span><span class="p" data-group-id="1027065945-10">{</span><span class="ss">from_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="1027065945-10">}</span><span class="p" data-group-id="1027065945-9">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Messages from shell to Client received in client/1 function</span><span class="w">
│ │ │  </span><span class="c1">%%% spawn(mess_client, client, [server_node(), Name])</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5099461185-11">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="5099461185-12">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="5099461185-12">}</span><span class="p" data-group-id="5099461185-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1027065945-11">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="1027065945-12">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="1027065945-12">}</span><span class="p" data-group-id="1027065945-11">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%% logoff</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%%----END FILE----</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE user_interface.erl----</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% User interface to the messenger program</span><span class="w">
│ │ │  </span><span class="c1">%%% login(Name)</span><span class="w">
│ │ │  </span><span class="c1">%%%     One user at a time can log in from each Erlang node in the</span><span class="w">
│ │ │ @@ -170,177 +170,177 @@
│ │ │  </span><span class="c1">%%%     Logs off anybody at that node</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% message(ToName, Message)</span><span class="w">
│ │ │  </span><span class="c1">%%%     sends Message to ToName. Error messages if the user of this</span><span class="w">
│ │ │  </span><span class="c1">%%%     function is not logged on or if ToName is not logged on at</span><span class="w">
│ │ │  </span><span class="c1">%%%     any node.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3923114774-1">(</span><span class="ss">user_interface</span><span class="p" data-group-id="3923114774-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3923114774-2">(</span><span class="p" data-group-id="3923114774-3">[</span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3923114774-3">]</span><span class="p" data-group-id="3923114774-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="3923114774-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="3923114774-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="3923114774-5">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="3923114774-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2290108610-1">(</span><span class="ss">user_interface</span><span class="p" data-group-id="2290108610-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2290108610-2">(</span><span class="p" data-group-id="2290108610-3">[</span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2290108610-3">]</span><span class="p" data-group-id="2290108610-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="2290108610-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="2290108610-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="2290108610-5">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="2290108610-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">logon</span><span class="p" data-group-id="3923114774-6">(</span><span class="n">Name</span><span class="p" data-group-id="3923114774-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="3923114774-7">(</span><span class="ss">mess_client</span><span class="p" data-group-id="3923114774-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">logon</span><span class="p" data-group-id="2290108610-6">(</span><span class="n">Name</span><span class="p" data-group-id="2290108610-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="2290108610-7">(</span><span class="ss">mess_client</span><span class="p" data-group-id="2290108610-7">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">register</span><span class="p" data-group-id="3923114774-8">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ -                     </span><span class="nf">spawn</span><span class="p" data-group-id="3923114774-9">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3923114774-10">[</span><span class="o">?</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="3923114774-10">]</span><span class="p" data-group-id="3923114774-9">)</span><span class="p" data-group-id="3923114774-8">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="nf">register</span><span class="p" data-group-id="2290108610-8">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ +                     </span><span class="nf">spawn</span><span class="p" data-group-id="2290108610-9">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2290108610-10">[</span><span class="o">?</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="2290108610-10">]</span><span class="p" data-group-id="2290108610-9">)</span><span class="p" data-group-id="2290108610-8">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">already_logged_on</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">logoff</span><span class="p" data-group-id="3923114774-11">(</span><span class="p" data-group-id="3923114774-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">logoff</span><span class="p" data-group-id="2290108610-11">(</span><span class="p" data-group-id="2290108610-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">logoff</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">message</span><span class="p" data-group-id="3923114774-12">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="3923114774-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="3923114774-13">(</span><span class="ss">mess_client</span><span class="p" data-group-id="3923114774-13">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ +</span><span class="nf">message</span><span class="p" data-group-id="2290108610-12">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2290108610-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="2290108610-13">(</span><span class="ss">mess_client</span><span class="p" data-group-id="2290108610-13">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">not_logged_on</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="3923114774-14">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="3923114774-14">}</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="2290108610-14">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="2290108610-14">}</span><span class="p">,</span><span class="w">
│ │ │               </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%%----END FILE----</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_client.erl----</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% The client process which runs on each user node</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7749347010-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="7749347010-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7749347010-2">(</span><span class="p" data-group-id="7749347010-3">[</span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7749347010-3">]</span><span class="p" data-group-id="7749347010-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="7749347010-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="7749347010-4">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="7749347010-5">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="7749347010-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7749347010-6">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="7749347010-6">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="7749347010-7">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="7749347010-8">(</span><span class="p" data-group-id="7749347010-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="7749347010-7">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">await_result</span><span class="p" data-group-id="7749347010-9">(</span><span class="p" data-group-id="7749347010-9">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="7749347010-10">(</span><span class="n">Server_Node</span><span class="p" data-group-id="7749347010-10">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2003991710-1">(</span><span class="ss">mess_client</span><span class="p" data-group-id="2003991710-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2003991710-2">(</span><span class="p" data-group-id="2003991710-3">[</span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2003991710-3">]</span><span class="p" data-group-id="2003991710-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="2003991710-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="2003991710-4">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="2003991710-5">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="2003991710-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2003991710-6">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="2003991710-6">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="2003991710-7">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="2003991710-8">(</span><span class="p" data-group-id="2003991710-8">)</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="2003991710-7">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">await_result</span><span class="p" data-group-id="2003991710-9">(</span><span class="p" data-group-id="2003991710-9">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="2003991710-10">(</span><span class="n">Server_Node</span><span class="p" data-group-id="2003991710-10">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="7749347010-11">(</span><span class="n">Server_Node</span><span class="p" data-group-id="7749347010-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="2003991710-11">(</span><span class="n">Server_Node</span><span class="p" data-group-id="2003991710-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">logoff</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="7749347010-12">(</span><span class="ss">normal</span><span class="p" data-group-id="7749347010-12">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="7749347010-13">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="7749347010-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="7749347010-14">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="7749347010-14">}</span><span class="w"> </span><span class="o">!</span><span class="w">
│ │ │ -                </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="7749347010-15">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="7749347010-16">(</span><span class="p" data-group-id="7749347010-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="7749347010-15">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">await_result</span><span class="p" data-group-id="7749347010-17">(</span><span class="p" data-group-id="7749347010-17">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7749347010-18">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="7749347010-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7749347010-19">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7749347010-20">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="7749347010-20">]</span><span class="p" data-group-id="7749347010-19">)</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="2003991710-12">(</span><span class="ss">normal</span><span class="p" data-group-id="2003991710-12">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="2003991710-13">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="2003991710-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="2003991710-14">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="2003991710-14">}</span><span class="w"> </span><span class="o">!</span><span class="w">
│ │ │ +                </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="2003991710-15">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="nf">self</span><span class="p" data-group-id="2003991710-16">(</span><span class="p" data-group-id="2003991710-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="2003991710-15">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">await_result</span><span class="p" data-group-id="2003991710-17">(</span><span class="p" data-group-id="2003991710-17">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2003991710-18">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2003991710-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2003991710-19">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2003991710-20">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="2003991710-20">]</span><span class="p" data-group-id="2003991710-19">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="7749347010-21">(</span><span class="n">Server_Node</span><span class="p" data-group-id="7749347010-21">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="2003991710-21">(</span><span class="n">Server_Node</span><span class="p" data-group-id="2003991710-21">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% wait for a response from the server</span><span class="w">
│ │ │ -</span><span class="nf">await_result</span><span class="p" data-group-id="7749347010-22">(</span><span class="p" data-group-id="7749347010-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">await_result</span><span class="p" data-group-id="2003991710-22">(</span><span class="p" data-group-id="2003991710-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="7749347010-23">{</span><span class="ss">message</span><span class="o">=</span><span class="n">Why</span><span class="p" data-group-id="7749347010-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7749347010-24">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7749347010-25">[</span><span class="n">Why</span><span class="p" data-group-id="7749347010-25">]</span><span class="p" data-group-id="7749347010-24">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="7749347010-26">(</span><span class="ss">normal</span><span class="p" data-group-id="7749347010-26">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="7749347010-27">{</span><span class="ss">message</span><span class="o">=</span><span class="n">What</span><span class="p" data-group-id="7749347010-27">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7749347010-28">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7749347010-29">[</span><span class="n">What</span><span class="p" data-group-id="7749347010-29">]</span><span class="p" data-group-id="7749347010-28">)</span><span class="w">
│ │ │ +        </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="2003991710-23">{</span><span class="ss">message</span><span class="o">=</span><span class="n">Why</span><span class="p" data-group-id="2003991710-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2003991710-24">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2003991710-25">[</span><span class="n">Why</span><span class="p" data-group-id="2003991710-25">]</span><span class="p" data-group-id="2003991710-24">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="2003991710-26">(</span><span class="ss">normal</span><span class="p" data-group-id="2003991710-26">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="2003991710-27">{</span><span class="ss">message</span><span class="o">=</span><span class="n">What</span><span class="p" data-group-id="2003991710-27">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2003991710-28">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2003991710-29">[</span><span class="n">What</span><span class="p" data-group-id="2003991710-29">]</span><span class="p" data-group-id="2003991710-28">)</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7749347010-30">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7749347010-31">[</span><span class="p" data-group-id="7749347010-31">]</span><span class="p" data-group-id="7749347010-30">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="7749347010-32">(</span><span class="ss">timeout</span><span class="p" data-group-id="7749347010-32">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2003991710-30">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2003991710-31">[</span><span class="p" data-group-id="2003991710-31">]</span><span class="p" data-group-id="2003991710-30">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="2003991710-32">(</span><span class="ss">timeout</span><span class="p" data-group-id="2003991710-32">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%%----END FILE---</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%%----FILE mess_server.erl----</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% This is the server process of the messenger service</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5655083166-1">(</span><span class="ss">mess_server</span><span class="p" data-group-id="5655083166-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5655083166-2">(</span><span class="p" data-group-id="5655083166-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5655083166-3">]</span><span class="p" data-group-id="5655083166-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="5655083166-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="5655083166-4">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="5655083166-5">(</span><span class="p" data-group-id="5655083166-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="5655083166-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5655083166-6">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">server</span><span class="p" data-group-id="5655083166-7">(</span><span class="p" data-group-id="5655083166-8">[</span><span class="p" data-group-id="5655083166-8">]</span><span class="p" data-group-id="5655083166-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6768367390-1">(</span><span class="ss">mess_server</span><span class="p" data-group-id="6768367390-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6768367390-2">(</span><span class="p" data-group-id="6768367390-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6768367390-3">]</span><span class="p" data-group-id="6768367390-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="6768367390-4">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="6768367390-4">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="6768367390-5">(</span><span class="p" data-group-id="6768367390-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="6768367390-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6768367390-6">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">server</span><span class="p" data-group-id="6768367390-7">(</span><span class="p" data-group-id="6768367390-8">[</span><span class="p" data-group-id="6768367390-8">]</span><span class="p" data-group-id="6768367390-7">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% the user list has the format [{ClientPid1, Name1},{ClientPid22, Name2},...]</span><span class="w">
│ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="5655083166-9">(</span><span class="n">User_List</span><span class="p" data-group-id="5655083166-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5655083166-10">(</span><span class="s">&quot;User list = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5655083166-11">[</span><span class="n">User_List</span><span class="p" data-group-id="5655083166-11">]</span><span class="p" data-group-id="5655083166-10">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="6768367390-9">(</span><span class="n">User_List</span><span class="p" data-group-id="6768367390-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6768367390-10">(</span><span class="s">&quot;User list = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6768367390-11">[</span><span class="n">User_List</span><span class="p" data-group-id="6768367390-11">]</span><span class="p" data-group-id="6768367390-10">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="5655083166-12">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="5655083166-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="5655083166-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-13">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="5655083166-14">(</span><span class="n">New_User_List</span><span class="p" data-group-id="5655083166-14">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5655083166-15">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="5655083166-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="5655083166-16">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-16">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="5655083166-17">(</span><span class="n">New_User_List</span><span class="p" data-group-id="5655083166-17">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="5655083166-18">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="5655083166-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="5655083166-19">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-19">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="5655083166-20">(</span><span class="n">User_List</span><span class="p" data-group-id="5655083166-20">)</span><span class="w">
│ │ │ +        </span><span class="o">#</span><span class="ss">logon</span><span class="p" data-group-id="6768367390-12">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">username</span><span class="o">=</span><span class="n">Name</span><span class="p" data-group-id="6768367390-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="6768367390-13">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-13">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="6768367390-14">(</span><span class="n">New_User_List</span><span class="p" data-group-id="6768367390-14">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="6768367390-15">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6768367390-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="6768367390-16">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-16">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="6768367390-17">(</span><span class="n">New_User_List</span><span class="p" data-group-id="6768367390-17">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="o">#</span><span class="ss">message</span><span class="p" data-group-id="6768367390-18">{</span><span class="ss">client_pid</span><span class="o">=</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="6768367390-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="6768367390-19">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-19">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="6768367390-20">(</span><span class="n">User_List</span><span class="p" data-group-id="6768367390-20">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Start the server</span><span class="w">
│ │ │ -</span><span class="nf">start_server</span><span class="p" data-group-id="5655083166-21">(</span><span class="p" data-group-id="5655083166-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="5655083166-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="5655083166-23">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5655083166-24">[</span><span class="p" data-group-id="5655083166-24">]</span><span class="p" data-group-id="5655083166-23">)</span><span class="p" data-group-id="5655083166-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_server</span><span class="p" data-group-id="6768367390-21">(</span><span class="p" data-group-id="6768367390-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="6768367390-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="6768367390-23">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6768367390-24">[</span><span class="p" data-group-id="6768367390-24">]</span><span class="p" data-group-id="6768367390-23">)</span><span class="p" data-group-id="6768367390-22">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Server adds a new user to the user list</span><span class="w">
│ │ │ -</span><span class="nf">server_logon</span><span class="p" data-group-id="5655083166-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_logon</span><span class="p" data-group-id="6768367390-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% check if logged on anywhere else</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="5655083166-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="6768367390-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="5655083166-27">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="5655083166-27">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="6768367390-27">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="6768367390-27">}</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">User_List</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="5655083166-28">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">logged_on</span><span class="p" data-group-id="5655083166-28">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">link</span><span class="p" data-group-id="5655083166-29">(</span><span class="n">From</span><span class="p" data-group-id="5655083166-29">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="5655083166-30">[</span><span class="p" data-group-id="5655083166-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5655083166-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="6768367390-28">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">logged_on</span><span class="p" data-group-id="6768367390-28">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">link</span><span class="p" data-group-id="6768367390-29">(</span><span class="n">From</span><span class="p" data-group-id="6768367390-29">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6768367390-30">[</span><span class="p" data-group-id="6768367390-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="6768367390-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Server deletes a user from the user list</span><span class="w">
│ │ │ -</span><span class="nf">server_logoff</span><span class="p" data-group-id="5655083166-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="5655083166-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-33">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">server_logoff</span><span class="p" data-group-id="6768367390-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="6768367390-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-33">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Server transfers a message between user</span><span class="w">
│ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="5655083166-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="6768367390-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% check that the user is logged on and who he is</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="5655083166-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="6768367390-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="5655083166-36">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="5655083166-36">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5655083166-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5655083166-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="5655083166-38">}</span><span class="p" data-group-id="5655083166-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="5655083166-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-39">)</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">abort_client</span><span class="p" data-group-id="6768367390-36">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="6768367390-36">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="6768367390-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6768367390-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="6768367390-38">}</span><span class="p" data-group-id="6768367390-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="6768367390-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-39">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%% If the user exists, send the message</span><span class="w">
│ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="5655083166-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="6768367390-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Find the receiver and send the message</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="5655083166-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="5655083166-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="6768367390-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="6768367390-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="5655083166-42">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">receiver_not_found</span><span class="p" data-group-id="5655083166-42">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5655083166-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5655083166-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="5655083166-44">}</span><span class="p" data-group-id="5655083166-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_from</span><span class="p" data-group-id="5655083166-45">{</span><span class="ss">from_name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="5655083166-45">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w">  </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="5655083166-46">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">sent</span><span class="p" data-group-id="5655083166-46">}</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="6768367390-42">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">receiver_not_found</span><span class="p" data-group-id="6768367390-42">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="6768367390-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6768367390-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="6768367390-44">}</span><span class="p" data-group-id="6768367390-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="o">#</span><span class="ss">message_from</span><span class="p" data-group-id="6768367390-45">{</span><span class="ss">from_name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="6768367390-45">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w">  </span><span class="o">#</span><span class="ss">server_reply</span><span class="p" data-group-id="6768367390-46">{</span><span class="ss">message</span><span class="o">=</span><span class="ss">sent</span><span class="p" data-group-id="6768367390-46">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%%----END FILE---</span></code></pre><h2 id="header-files" class="section-heading">
│ │ │    <a href="#header-files" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Header Files</span>
│ │ │  </h2>
│ │ │  <p>As shown above, some files have extension <code class="inline">.hrl</code>. These are header files that
│ │ │ -are included in the <code class="inline">.erl</code> files by:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="4931434800-1">(</span><span class="s">&quot;File_Name&quot;</span><span class="p" data-group-id="4931434800-1">)</span><span class="p">.</span></code></pre><p>for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="2239228591-1">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="2239228591-1">)</span><span class="p">.</span></code></pre><p>In the case above the file is fetched from the same directory as all the other
│ │ │ +are included in the <code class="inline">.erl</code> files by:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="6413258804-1">(</span><span class="s">&quot;File_Name&quot;</span><span class="p" data-group-id="6413258804-1">)</span><span class="p">.</span></code></pre><p>for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="3561170190-1">(</span><span class="s">&quot;mess_interface.hrl&quot;</span><span class="p" data-group-id="3561170190-1">)</span><span class="p">.</span></code></pre><p>In the case above the file is fetched from the same directory as all the other
│ │ │  files in the messenger example. (<em>manual</em>).</p><p>.hrl files can contain any valid Erlang code but are most often used for record
│ │ │  and macro definitions.</p><h2 id="records" class="section-heading">
│ │ │    <a href="#records" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Records</span>
│ │ │  </h2>
│ │ │ -<p>A record is defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6299045694-1">(</span><span class="ss">name_of_record</span><span class="p">,</span><span class="p" data-group-id="6299045694-2">{</span><span class="ss">field_name1</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name2</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6299045694-2">}</span><span class="p" data-group-id="6299045694-1">)</span><span class="p">.</span></code></pre><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8124194487-1">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="8124194487-2">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="8124194487-2">}</span><span class="p" data-group-id="8124194487-1">)</span><span class="p">.</span></code></pre><p>This is equivalent to:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1359521716-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To_Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="1359521716-1">}</span></code></pre><p>Creating a record is best illustrated by an example:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="2171308975-1">{</span><span class="ss">message</span><span class="o">=</span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="ss">fred</span><span class="p">)</span></code></pre><p>This creates:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7823668923-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="7823668923-1">}</span></code></pre><p>Notice that you do not have to worry about the order you assign values to the
│ │ │ +<p>A record is defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4461145314-1">(</span><span class="ss">name_of_record</span><span class="p">,</span><span class="p" data-group-id="4461145314-2">{</span><span class="ss">field_name1</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name2</span><span class="p">,</span><span class="w"> </span><span class="ss">field_name3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4461145314-2">}</span><span class="p" data-group-id="4461145314-1">)</span><span class="p">.</span></code></pre><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8313242735-1">(</span><span class="ss">message_to</span><span class="p">,</span><span class="p" data-group-id="8313242735-2">{</span><span class="ss">to_name</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p" data-group-id="8313242735-2">}</span><span class="p" data-group-id="8313242735-1">)</span><span class="p">.</span></code></pre><p>This is equivalent to:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6406861393-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To_Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="6406861393-1">}</span></code></pre><p>Creating a record is best illustrated by an example:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="5813752814-1">{</span><span class="ss">message</span><span class="o">=</span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">to_name</span><span class="o">=</span><span class="ss">fred</span><span class="p">)</span></code></pre><p>This creates:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5239244673-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="ss">fred</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="5239244673-1">}</span></code></pre><p>Notice that you do not have to worry about the order you assign values to the
│ │ │  various parts of the records when you create it. The advantage of using records
│ │ │  is that by placing their definitions in header files you can conveniently define
│ │ │  interfaces that are easy to change. For example, if you want to add a new field
│ │ │  to the record, you only have to change the code where the new field is used and
│ │ │  not at every place the record is referred to. If you leave out a field when
│ │ │  creating a record, it gets the value of the atom <code class="inline">undefined</code>. (<em>manual</em>)</p><p>Pattern matching with records is very similar to creating records. For example,
│ │ │ -inside a <code class="inline">case</code> or <code class="inline">receive</code>:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="5780925595-1">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="5780925595-1">}</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>This is the same as:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4503540092-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="4503540092-1">}</span></code></pre><h2 id="macros" class="section-heading">
│ │ │ +inside a <code class="inline">case</code> or <code class="inline">receive</code>:</p><pre><code class="makeup erlang" translate="no"><span class="o">#</span><span class="ss">message_to</span><span class="p" data-group-id="2119517745-1">{</span><span class="ss">to_name</span><span class="o">=</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="o">=</span><span class="n">Message</span><span class="p" data-group-id="2119517745-1">}</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>This is the same as:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9081964551-1">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="9081964551-1">}</span></code></pre><h2 id="macros" class="section-heading">
│ │ │    <a href="#macros" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Macros</span>
│ │ │  </h2>
│ │ │  <p>Another thing that has been added to the messenger is a macro. The file
│ │ │  <code class="inline">mess_config.hrl</code> contains the definition:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Configure the location of the server node,</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7896012046-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="7896012046-1">)</span><span class="p">.</span></code></pre><p>This file is included in <code class="inline">mess_server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="7720821536-1">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="7720821536-1">)</span><span class="p">.</span></code></pre><p>Every occurrence of <code class="inline">?server_node</code> in <code class="inline">mess_server.erl</code> is now replaced by
│ │ │ -<code class="inline">messenger@super</code>.</p><p>A macro is also used when spawning the server process:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="8642228266-1">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8642228266-2">[</span><span class="p" data-group-id="8642228266-2">]</span><span class="p" data-group-id="8642228266-1">)</span></code></pre><p>This is a standard macro (that is, defined by the system, not by the user).
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1944419171-1">(</span><span class="ss">server_node</span><span class="p">,</span><span class="w"> </span><span class="ss">messenger@super</span><span class="p" data-group-id="1944419171-1">)</span><span class="p">.</span></code></pre><p>This file is included in <code class="inline">mess_server.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include</span><span class="p" data-group-id="4251645393-1">(</span><span class="s">&quot;mess_config.hrl&quot;</span><span class="p" data-group-id="4251645393-1">)</span><span class="p">.</span></code></pre><p>Every occurrence of <code class="inline">?server_node</code> in <code class="inline">mess_server.erl</code> is now replaced by
│ │ │ +<code class="inline">messenger@super</code>.</p><p>A macro is also used when spawning the server process:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="7832392208-1">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7832392208-2">[</span><span class="p" data-group-id="7832392208-2">]</span><span class="p" data-group-id="7832392208-1">)</span></code></pre><p>This is a standard macro (that is, defined by the system, not by the user).
│ │ │  <code class="inline">?MODULE</code> is always replaced by the name of the current module (that is, the
│ │ │  <code class="inline">-module</code> definition near the start of the file). There are more advanced ways
│ │ │  of using macros with, for example, <a href="macros.html#defining-and-using-macros">parameters</a>.</p><p>The three Erlang (<code class="inline">.erl</code>) files in the messenger example are individually
│ │ │  compiled into object code file (<code class="inline">.beam</code>). The Erlang system loads and links
│ │ │  these files into the system when they are referred to during execution of the
│ │ │  code. In this case, they are simply put in our current working directory (that
│ │ │  is, the place you have done &quot;cd&quot; to). There are ways of putting the <code class="inline">.beam</code>
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/ref_man_functions.html
│ │ │ @@ -120,51 +120,51 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Function Declaration Syntax</span>
│ │ │  </h2>
│ │ │  <p>A <em>function declaration</em> is a sequence of function clauses separated by
│ │ │  semicolons, and terminated by a period (<code class="inline">.</code>).</p><p>A <em>function clause</em> consists of a <em>clause head</em> and a <em>clause body</em>, separated by
│ │ │  <code class="inline">-&gt;</code>.</p><p>A clause <em>head</em> consists of the function name, an argument list, and an optional
│ │ │ -guard sequence beginning with the keyword <code class="inline">when</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="p" data-group-id="0514562890-1">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="0514562890-1">)</span><span class="w"> </span><span class="p" data-group-id="0514562890-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="0514562890-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +guard sequence beginning with the keyword <code class="inline">when</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">Name</span><span class="p" data-group-id="4716909152-1">(</span><span class="n">Pattern11</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">Pattern1N</span><span class="p" data-group-id="4716909152-1">)</span><span class="w"> </span><span class="p" data-group-id="4716909152-2">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeq1</span><span class="p" data-group-id="4716909152-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Body1</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="n">Name</span><span class="p" data-group-id="0514562890-3">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="0514562890-3">)</span><span class="w"> </span><span class="p" data-group-id="0514562890-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="0514562890-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="n">Name</span><span class="p" data-group-id="4716909152-3">(</span><span class="n">PatternK1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">PatternKN</span><span class="p" data-group-id="4716909152-3">)</span><span class="w"> </span><span class="p" data-group-id="4716909152-4">[</span><span class="k">when</span><span class="w"> </span><span class="n">GuardSeqK</span><span class="p" data-group-id="4716909152-4">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">BodyK</span><span class="p">.</span></code></pre><p>The function name is an atom. Each argument is a pattern.</p><p>The number of arguments <code class="inline">N</code> is the <em>arity</em> of the function. A function is
│ │ │  uniquely defined by the module name, function name, and arity. That is, two
│ │ │  functions with the same name and in the same module, but with different arities
│ │ │  are two different functions.</p><p>A function named <code class="inline">f</code> in module <code class="inline">mod</code> and with arity <code class="inline">N</code> is often denoted as
│ │ │  <code class="inline">mod:f/N</code>.</p><p>A clause <em>body</em> consists of a sequence of expressions separated by comma (<code class="inline">,</code>):</p><pre><code class="text">Expr1,
│ │ │  ...,
│ │ │  ExprN</code></pre><p>Valid Erlang expressions and guard sequences are described in
│ │ │ -<a href="expressions.html">Expressions</a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">fact</span><span class="p" data-group-id="5120197460-1">(</span><span class="n">N</span><span class="p" data-group-id="5120197460-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% first clause head</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="5120197460-2">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="5120197460-2">)</span><span class="p">;</span><span class="w">     </span><span class="c1">% first clause body</span><span class="w">
│ │ │ +<a href="expressions.html">Expressions</a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">fact</span><span class="p" data-group-id="8660517251-1">(</span><span class="n">N</span><span class="p" data-group-id="8660517251-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% first clause head</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="8660517251-2">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="8660517251-2">)</span><span class="p">;</span><span class="w">     </span><span class="c1">% first clause body</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="5120197460-3">(</span><span class="mi">0</span><span class="p" data-group-id="5120197460-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">             </span><span class="c1">% second clause head</span><span class="w">
│ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="8660517251-3">(</span><span class="mi">0</span><span class="p" data-group-id="8660517251-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">             </span><span class="c1">% second clause head</span><span class="w">
│ │ │      </span><span class="mi">1</span><span class="p">.</span><span class="w">                 </span><span class="c1">% second clause body</span></code></pre><p><a href="" id="eval"></a></p><h2 id="function-evaluation" class="section-heading">
│ │ │    <a href="#function-evaluation" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Function Evaluation</span>
│ │ │  </h2>
│ │ │  <p>When a function <code class="inline">M:F/N</code> is called, first the code for the function is located.
│ │ │  If the function cannot be found, an <code class="inline">undef</code> runtime error occurs. Notice that
│ │ │  the function must be exported to be visible outside the module it is defined in.</p><p>If the function is found, the function clauses are scanned sequentially until a
│ │ │  clause is found that fulfills both of the following two conditions:</p><ol><li>The patterns in the clause head can be successfully matched against the given
│ │ │  arguments.</li><li>The guard sequence, if any, is true.</li></ol><p>If such a clause cannot be found, a <code class="inline">function_clause</code> runtime error occurs.</p><p>If such a clause is found, the corresponding clause body is evaluated. That is,
│ │ │  the expressions in the body are evaluated sequentially and the value of the last
│ │ │ -expression is returned.</p><p>Consider the function <code class="inline">fact</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9656963982-1">(</span><span class="ss">mod</span><span class="p" data-group-id="9656963982-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9656963982-2">(</span><span class="p" data-group-id="9656963982-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9656963982-3">]</span><span class="p" data-group-id="9656963982-2">)</span><span class="p">.</span><span class="w">
│ │ │ +expression is returned.</p><p>Consider the function <code class="inline">fact</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2961601149-1">(</span><span class="ss">mod</span><span class="p" data-group-id="2961601149-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2961601149-2">(</span><span class="p" data-group-id="2961601149-3">[</span><span class="ss">fact</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2961601149-3">]</span><span class="p" data-group-id="2961601149-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="9656963982-4">(</span><span class="n">N</span><span class="p" data-group-id="9656963982-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="9656963982-5">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="9656963982-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">fact</span><span class="p" data-group-id="9656963982-6">(</span><span class="mi">0</span><span class="p" data-group-id="9656963982-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="2961601149-4">(</span><span class="n">N</span><span class="p" data-group-id="2961601149-4">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="2961601149-5">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="2961601149-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">fact</span><span class="p" data-group-id="2961601149-6">(</span><span class="mi">0</span><span class="p" data-group-id="2961601149-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="mi">1</span><span class="p">.</span></code></pre><p>Assume that you want to calculate the factorial for 1:</p><pre><code class="text">1&gt; mod:fact(1).</code></pre><p>Evaluation starts at the first clause. The pattern <code class="inline">N</code> is matched against
│ │ │  argument 1. The matching succeeds and the guard (<code class="inline">N &gt; 0</code>) is true, thus <code class="inline">N</code> is
│ │ │ -bound to 1, and the corresponding body is evaluated:</p><pre><code class="makeup erlang" translate="no"><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="7955812996-1">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="7955812996-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7955812996-2">(</span><span class="n">N</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">bound</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7955812996-2">)</span><span class="w">
│ │ │ -</span><span class="mi">1</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="7955812996-3">(</span><span class="mi">0</span><span class="p" data-group-id="7955812996-3">)</span></code></pre><p>Now, <code class="inline">fact(0)</code> is called, and the function clauses are scanned
│ │ │ +bound to 1, and the corresponding body is evaluated:</p><pre><code class="makeup erlang" translate="no"><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="1518246277-1">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="1518246277-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1518246277-2">(</span><span class="n">N</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">bound</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="1518246277-2">)</span><span class="w">
│ │ │ +</span><span class="mi">1</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fact</span><span class="p" data-group-id="1518246277-3">(</span><span class="mi">0</span><span class="p" data-group-id="1518246277-3">)</span></code></pre><p>Now, <code class="inline">fact(0)</code> is called, and the function clauses are scanned
│ │ │  sequentially again. First, the pattern <code class="inline">N</code> is matched against 0. The
│ │ │  matching succeeds, but the guard (<code class="inline">N &gt; 0</code>) is false. Second, the
│ │ │  pattern <code class="inline">0</code> is matched against the argument <code class="inline">0</code>. The matching succeeds
│ │ │  and the body is evaluated:</p><pre><code class="text">1 * fact(0) =&gt;
│ │ │  1 * 1 =&gt;
│ │ │  1</code></pre><p>Evaluation has succeed and <code class="inline">mod:fact(1)</code> returns 1.</p><p>If <code class="inline">mod:fact/1</code> is called with a negative number as argument, no clause head
│ │ │  matches. A <code class="inline">function_clause</code> runtime error occurs.</p><h2 id="tail-recursion" class="section-heading">
│ │ │ @@ -173,17 +173,17 @@
│ │ │    </a>
│ │ │    <span class="text">Tail recursion</span>
│ │ │  </h2>
│ │ │  <p>If the last expression of a function body is a function call, a
│ │ │  <em>tail-recursive call</em> is done. This is to ensure that no system
│ │ │  resources, for example, call stack, are consumed. This means that an
│ │ │  infinite loop using tail-recursive calls will not exhaust the call
│ │ │ -stack and can (in principle) run forever.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="6782538608-1">(</span><span class="n">N</span><span class="p" data-group-id="6782538608-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6782538608-2">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6782538608-3">[</span><span class="n">N</span><span class="p" data-group-id="6782538608-3">]</span><span class="p" data-group-id="6782538608-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="6782538608-4">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="6782538608-4">)</span><span class="p">.</span></code></pre><p>The earlier factorial example is a counter-example. It is not
│ │ │ +stack and can (in principle) run forever.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="7369381861-1">(</span><span class="n">N</span><span class="p" data-group-id="7369381861-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7369381861-2">(</span><span class="s">&quot;</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7369381861-3">[</span><span class="n">N</span><span class="p" data-group-id="7369381861-3">]</span><span class="p" data-group-id="7369381861-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="7369381861-4">(</span><span class="n">N</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="7369381861-4">)</span><span class="p">.</span></code></pre><p>The earlier factorial example is a counter-example. It is not
│ │ │  tail-recursive, since a multiplication is done on the result of the recursive
│ │ │  call to <code class="inline">fact(N-1)</code>.</p><h2 id="built-in-functions-bifs" class="section-heading">
│ │ │    <a href="#built-in-functions-bifs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Built-In Functions (BIFs)</span>
│ │ │  </h2>
│ │ │ @@ -191,17 +191,17 @@
│ │ │  system. BIFs do things that are difficult or impossible to implement
│ │ │  in Erlang. Most of the BIFs belong to module <a href="../../erts-15.2.7.3/doc/html/erlang.html"><code class="inline">erlang</code></a>, but there
│ │ │  are also BIFs belonging to a few other modules, for example <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html"><code class="inline">lists</code></a>
│ │ │  and <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html"><code class="inline">ets</code></a>.</p><p>The most commonly used BIFs belonging to <a href="../../erts-15.2.7.3/doc/html/erlang.html"><code class="inline">erlang</code></a> are <em>auto-imported</em>. They do
│ │ │  not need to be prefixed with the module name. Which BIFs that are auto-imported
│ │ │  is specified in the <a href="../../erts-15.2.7.3/doc/html/erlang.html"><code class="inline">erlang</code></a> module in ERTS. For example, standard-type
│ │ │  conversion BIFs like <code class="inline">atom_to_list</code> and BIFs allowed in guards can be called
│ │ │ -without specifying the module name.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="8530081492-1">(</span><span class="p" data-group-id="8530081492-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8530081492-2">}</span><span class="p" data-group-id="8530081492-1">)</span><span class="p">.</span><span class="w">
│ │ │ +without specifying the module name.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="3586462165-1">(</span><span class="p" data-group-id="3586462165-2">{</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3586462165-2">}</span><span class="p" data-group-id="3586462165-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="8530081492-3">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="8530081492-3">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="3586462165-3">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="3586462165-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;Erlang&quot;</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="documentation.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/ref_man_processes.html
│ │ │ @@ -125,18 +125,18 @@
│ │ │  (grow and shrink dynamically) with small memory footprint, fast to create and
│ │ │  terminate, and the scheduling overhead is low.</p><h2 id="process-creation" class="section-heading">
│ │ │    <a href="#process-creation" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Process Creation</span>
│ │ │  </h2>
│ │ │ -<p>A process is created by calling <a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn/3"><code class="inline">spawn()</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="7968797509-1">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="7968797509-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pid</span><span class="p" data-group-id="7968797509-2">(</span><span class="p" data-group-id="7968797509-2">)</span><span class="w">
│ │ │ -  </span><span class="n">Module</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="7968797509-3">(</span><span class="p" data-group-id="7968797509-3">)</span><span class="w">
│ │ │ -  </span><span class="n">Args</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7968797509-4">[</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="7968797509-4">]</span><span class="w">
│ │ │ -    </span><span class="n">ArgI</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="7968797509-5">(</span><span class="p" data-group-id="7968797509-5">)</span></code></pre><p><code class="inline">spawn()</code> creates a new process and returns the pid.</p><p>The new process starts executing in <code class="inline">Module:Name(Arg1,...,ArgN)</code> where the
│ │ │ +<p>A process is created by calling <a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn/3"><code class="inline">spawn()</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">spawn</span><span class="p" data-group-id="2339926015-1">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Args</span><span class="p" data-group-id="2339926015-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pid</span><span class="p" data-group-id="2339926015-2">(</span><span class="p" data-group-id="2339926015-2">)</span><span class="w">
│ │ │ +  </span><span class="n">Module</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="2339926015-3">(</span><span class="p" data-group-id="2339926015-3">)</span><span class="w">
│ │ │ +  </span><span class="n">Args</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2339926015-4">[</span><span class="n">Arg1</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="n">ArgN</span><span class="p" data-group-id="2339926015-4">]</span><span class="w">
│ │ │ +    </span><span class="n">ArgI</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="2339926015-5">(</span><span class="p" data-group-id="2339926015-5">)</span></code></pre><p><code class="inline">spawn()</code> creates a new process and returns the pid.</p><p>The new process starts executing in <code class="inline">Module:Name(Arg1,...,ArgN)</code> where the
│ │ │  arguments are the elements of the (possible empty) <code class="inline">Args</code> argument list.</p><p>There exist a number of different <code class="inline">spawn</code> BIFs:</p><ul><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn/4"><code class="inline">spawn/1,2,3,4</code></a></li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn_link/4"><code class="inline">spawn_link/1,2,3,4</code></a></li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn_monitor/4"><code class="inline">spawn_monitor/1,2,3,4</code></a></li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn_opt/5"><code class="inline">spawn_opt/2,3,4,5</code></a></li><li><a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn_request/5"><code class="inline">spawn_request/1,2,3,4,5</code></a></li></ul><h2 id="registered-processes" class="section-heading">
│ │ │    <a href="#registered-processes" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Registered Processes</span>
│ │ │  </h2>
│ │ │  <p>Besides addressing a process by using its pid, there are also BIFs for
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/ref_man_records.html
│ │ │ @@ -123,17 +123,17 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Defining Records</span>
│ │ │  </h2>
│ │ │  <p>A record definition consists of the name of the record, followed by the field
│ │ │  names of the record. Record and field names must be atoms. Each field can be
│ │ │  given an optional default value. If no default value is supplied, <code class="inline">undefined</code> is
│ │ │ -used.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7354358258-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7354358258-2">{</span><span class="n">Field1</span><span class="w"> </span><span class="p" data-group-id="7354358258-3">[</span><span class="o">=</span><span class="w"> </span><span class="n">Expr1</span><span class="p" data-group-id="7354358258-3">]</span><span class="p">,</span><span class="w">
│ │ │ +used.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5927082865-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5927082865-2">{</span><span class="n">Field1</span><span class="w"> </span><span class="p" data-group-id="5927082865-3">[</span><span class="o">=</span><span class="w"> </span><span class="n">Expr1</span><span class="p" data-group-id="5927082865-3">]</span><span class="p">,</span><span class="w">
│ │ │                 </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -               </span><span class="n">FieldN</span><span class="w"> </span><span class="p" data-group-id="7354358258-4">[</span><span class="o">=</span><span class="w"> </span><span class="n">ExprN</span><span class="p" data-group-id="7354358258-4">]</span><span class="p" data-group-id="7354358258-2">}</span><span class="p" data-group-id="7354358258-1">)</span><span class="p">.</span></code></pre><p>The default value for a field is an arbitrary expression, except that it must
│ │ │ +               </span><span class="n">FieldN</span><span class="w"> </span><span class="p" data-group-id="5927082865-4">[</span><span class="o">=</span><span class="w"> </span><span class="n">ExprN</span><span class="p" data-group-id="5927082865-4">]</span><span class="p" data-group-id="5927082865-2">}</span><span class="p" data-group-id="5927082865-1">)</span><span class="p">.</span></code></pre><p>The default value for a field is an arbitrary expression, except that it must
│ │ │  not use any variables.</p><p>A record definition can be placed anywhere among the attributes and function
│ │ │  declarations of a module, but the definition must come before any usage of the
│ │ │  record.</p><p>If a record is used in several modules, it is recommended that the record
│ │ │  definition is placed in an include file.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Starting from Erlang/OTP 26, records can be defined in the Erlang shell
│ │ │  using the syntax described in this section. In earlier releases, it was
│ │ │  necessary to use the <a href="../../lib/stdlib-6.2.2.2/doc/html/shell.html"><code class="inline">shell</code></a> built-in function <code class="inline">rd/2</code>.</p></section><h2 id="creating-records" class="section-heading">
│ │ │    <a href="#creating-records" class="hover-link">
│ │ │ @@ -143,32 +143,32 @@
│ │ │  </h2>
│ │ │  <p>The following expression creates a new <code class="inline">Name</code> record where the value of each
│ │ │  field <code class="inline">FieldI</code> is the value of evaluating the corresponding expression <code class="inline">ExprI</code>:</p><pre><code class="text">#Name{Field1=Expr1, ..., FieldK=ExprK}</code></pre><p>The fields can be in any order, not necessarily the same order as in the record
│ │ │  definition, and fields can be omitted. Omitted fields get their respective
│ │ │  default value instead.</p><p>If several fields are to be assigned the same value, the following construction
│ │ │  can be used:</p><pre><code class="text">#Name{Field1=Expr1, ..., FieldK=ExprK, _=ExprL}</code></pre><p>Omitted fields then get the value of evaluating <code class="inline">ExprL</code> instead of their default
│ │ │  values. This feature is primarily intended to be used to create patterns for ETS
│ │ │ -and Mnesia match functions.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9138026839-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9138026839-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="9138026839-2">}</span><span class="p" data-group-id="9138026839-1">)</span><span class="p">.</span><span class="w">
│ │ │ +and Mnesia match functions.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6017567423-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6017567423-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="6017567423-2">}</span><span class="p" data-group-id="6017567423-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">lookup</span><span class="p" data-group-id="9138026839-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="9138026839-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="9138026839-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9138026839-5">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="9138026839-5">}</span><span class="p" data-group-id="9138026839-4">)</span><span class="p">.</span></code></pre><h2 id="accessing-record-fields" class="section-heading">
│ │ │ +</span><span class="nf">lookup</span><span class="p" data-group-id="6017567423-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="6017567423-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="6017567423-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6017567423-5">{</span><span class="ss">name</span><span class="o">=</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="6017567423-5">}</span><span class="p" data-group-id="6017567423-4">)</span><span class="p">.</span></code></pre><h2 id="accessing-record-fields" class="section-heading">
│ │ │    <a href="#accessing-record-fields" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Accessing Record Fields</span>
│ │ │  </h2>
│ │ │  <pre><code class="text">Expr#Name.Field</code></pre><p>Returns the value of the specified field. <code class="inline">Expr</code> is to evaluate to a <code class="inline">Name</code>
│ │ │ -record.</p><p><em>Example</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4206309056-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4206309056-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="4206309056-2">}</span><span class="p" data-group-id="4206309056-1">)</span><span class="p">.</span><span class="w">
│ │ │ +record.</p><p><em>Example</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3007147492-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3007147492-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="3007147492-2">}</span><span class="p" data-group-id="3007147492-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">get_person_name</span><span class="p" data-group-id="4206309056-3">(</span><span class="n">Person</span><span class="p" data-group-id="4206309056-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">get_person_name</span><span class="p" data-group-id="3007147492-3">(</span><span class="n">Person</span><span class="p" data-group-id="3007147492-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">.</span></code></pre><p>The following expression returns the position of the specified field in the
│ │ │ -tuple representation of the record:</p><pre><code class="text">#Name.Field</code></pre><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8820012977-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8820012977-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="8820012977-2">}</span><span class="p" data-group-id="8820012977-1">)</span><span class="p">.</span><span class="w">
│ │ │ +tuple representation of the record:</p><pre><code class="text">#Name.Field</code></pre><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5699035907-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5699035907-2">{</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">phone</span><span class="p">,</span><span class="w"> </span><span class="ss">address</span><span class="p" data-group-id="5699035907-2">}</span><span class="p" data-group-id="5699035907-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">lookup</span><span class="p" data-group-id="8820012977-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="8820012977-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="8820012977-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="8820012977-4">)</span><span class="p">.</span></code></pre><h2 id="updating-records" class="section-heading">
│ │ │ +</span><span class="nf">lookup</span><span class="p" data-group-id="5699035907-3">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5699035907-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keyfind</span><span class="p" data-group-id="5699035907-4">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="5699035907-4">)</span><span class="p">.</span></code></pre><h2 id="updating-records" class="section-heading">
│ │ │    <a href="#updating-records" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Updating Records</span>
│ │ │  </h2>
│ │ │  <pre><code class="text">Expr#Name{Field1=Expr1, ..., FieldK=ExprK}</code></pre><p><code class="inline">Expr</code> is to evaluate to a <code class="inline">Name</code> record. A copy of this record is returned,
│ │ │  with the value of each specified field <code class="inline">FieldI</code> changed to the value of
│ │ │ @@ -178,51 +178,51 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Records in Guards</span>
│ │ │  </h2>
│ │ │  <p>Since record expressions are expanded to tuple expressions, creating
│ │ │  records and accessing record fields are allowed in guards. However,
│ │ │  all subexpressions (for initializing fields), must be valid guard
│ │ │ -expressions as well.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="7520281373-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7520281373-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Msg</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">#</span><span class="ss">msg</span><span class="p" data-group-id="7520281373-2">{</span><span class="ss">to</span><span class="o">=</span><span class="ss">void</span><span class="p">,</span><span class="w"> </span><span class="ss">no</span><span class="o">=</span><span class="mi">3</span><span class="p" data-group-id="7520281373-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +expressions as well.</p><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">handle</span><span class="p" data-group-id="4026113953-1">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4026113953-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Msg</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="o">#</span><span class="ss">msg</span><span class="p" data-group-id="4026113953-2">{</span><span class="ss">to</span><span class="o">=</span><span class="ss">void</span><span class="p">,</span><span class="w"> </span><span class="ss">no</span><span class="o">=</span><span class="mi">3</span><span class="p" data-group-id="4026113953-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle</span><span class="p" data-group-id="7520281373-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="7520281373-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">running</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>There is also a type test BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_record/2"><code class="inline">is_record(Term, RecordTag)</code></a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_person</span><span class="p" data-group-id="1873314805-1">(</span><span class="n">P</span><span class="p" data-group-id="1873314805-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="1873314805-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="1873314805-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle</span><span class="p" data-group-id="4026113953-3">(</span><span class="n">Msg</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4026113953-3">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">State</span><span class="o">#</span><span class="ss">state</span><span class="p">.</span><span class="ss">running</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>There is also a type test BIF <a href="../../erts-15.2.7.3/doc/html/erlang.html#is_record/2"><code class="inline">is_record(Term, RecordTag)</code></a>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="nf">is_person</span><span class="p" data-group-id="6007076688-1">(</span><span class="n">P</span><span class="p" data-group-id="6007076688-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_record</span><span class="p" data-group-id="6007076688-2">(</span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="6007076688-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">true</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">is_person</span><span class="p" data-group-id="1873314805-3">(</span><span class="p">_</span><span class="n">P</span><span class="p" data-group-id="1873314805-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">is_person</span><span class="p" data-group-id="6007076688-3">(</span><span class="p">_</span><span class="n">P</span><span class="p" data-group-id="6007076688-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">false</span><span class="p">.</span></code></pre><h2 id="records-in-patterns" class="section-heading">
│ │ │    <a href="#records-in-patterns" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Records in Patterns</span>
│ │ │  </h2>
│ │ │  <p>A pattern that matches a certain record is created in the same way as a record
│ │ │  is created:</p><pre><code class="text">#Name{Field1=Expr1, ..., FieldK=ExprK}</code></pre><p>In this case, one or more of <code class="inline">Expr1</code> ... <code class="inline">ExprK</code> can be unbound variables.</p><h2 id="nested-records" class="section-heading">
│ │ │    <a href="#nested-records" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Nested Records</span>
│ │ │  </h2>
│ │ │ -<p>Assume the following record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3290699045-1">(</span><span class="ss">nrec0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3290699045-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested0&quot;</span><span class="p" data-group-id="3290699045-2">}</span><span class="p" data-group-id="3290699045-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3290699045-3">(</span><span class="ss">nrec1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3290699045-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec0</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec0</span><span class="p" data-group-id="3290699045-5">{</span><span class="p" data-group-id="3290699045-5">}</span><span class="p" data-group-id="3290699045-4">}</span><span class="p" data-group-id="3290699045-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3290699045-6">(</span><span class="ss">nrec2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3290699045-7">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested2&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec1</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec1</span><span class="p" data-group-id="3290699045-8">{</span><span class="p" data-group-id="3290699045-8">}</span><span class="p" data-group-id="3290699045-7">}</span><span class="p" data-group-id="3290699045-6">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Assume the following record definitions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="0192211482-1">(</span><span class="ss">nrec0</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0192211482-2">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested0&quot;</span><span class="p" data-group-id="0192211482-2">}</span><span class="p" data-group-id="0192211482-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="0192211482-3">(</span><span class="ss">nrec1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0192211482-4">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested1&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec0</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec0</span><span class="p" data-group-id="0192211482-5">{</span><span class="p" data-group-id="0192211482-5">}</span><span class="p" data-group-id="0192211482-4">}</span><span class="p" data-group-id="0192211482-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="0192211482-6">(</span><span class="ss">nrec2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0192211482-7">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">&quot;nested2&quot;</span><span class="p">,</span><span class="w"> </span><span class="ss">nrec1</span><span class="o">=</span><span class="o">#</span><span class="ss">nrec1</span><span class="p" data-group-id="0192211482-8">{</span><span class="p" data-group-id="0192211482-8">}</span><span class="p" data-group-id="0192211482-7">}</span><span class="p" data-group-id="0192211482-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">N2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">nrec2</span><span class="p" data-group-id="3290699045-9">{</span><span class="p" data-group-id="3290699045-9">}</span><span class="p">,</span></code></pre><p>Accessing or updating nested records can be written without parentheses:</p><pre><code class="text">&quot;nested0&quot; = N2#nrec2.nrec1#nrec1.nrec0#nrec0.name,
│ │ │ +</span><span class="n">N2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">#</span><span class="ss">nrec2</span><span class="p" data-group-id="0192211482-9">{</span><span class="p" data-group-id="0192211482-9">}</span><span class="p">,</span></code></pre><p>Accessing or updating nested records can be written without parentheses:</p><pre><code class="text">&quot;nested0&quot; = N2#nrec2.nrec1#nrec1.nrec0#nrec0.name,
│ │ │      N0n = N2#nrec2.nrec1#nrec1.nrec0#nrec0{name = &quot;nested0a&quot;},</code></pre><p>which is equivalent to:</p><pre><code class="text">&quot;nested0&quot; = ((N2#nrec2.nrec1)#nrec1.nrec0)#nrec0.name,
│ │ │  N0n = ((N2#nrec2.nrec1)#nrec1.nrec0)#nrec0{name = &quot;nested0a&quot;},</code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP R14, parentheses were necessary when accessing or updating
│ │ │  nested records.</p></section><h2 id="internal-representation-of-records" class="section-heading">
│ │ │    <a href="#internal-representation-of-records" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Internal Representation of Records</span>
│ │ │  </h2>
│ │ │  <p>Record expressions are translated to tuple expressions during compilation. A
│ │ │ -record defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="6259125186-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6259125186-2">{</span><span class="n">Field1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">FieldN</span><span class="p" data-group-id="6259125186-2">}</span><span class="p" data-group-id="6259125186-1">)</span><span class="p">.</span></code></pre><p>is internally represented by the tuple:</p><pre><code class="text">{Name, Value1, ..., ValueN}</code></pre><p>Here each <code class="inline">ValueI</code> is the default value for <code class="inline">FieldI</code>.</p><p>To each module using records, a pseudo function is added during compilation to
│ │ │ -obtain information about records:</p><pre><code class="makeup erlang" translate="no"><span class="nf">record_info</span><span class="p" data-group-id="2490351793-1">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="2490351793-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2490351793-2">[</span><span class="n">Field</span><span class="p" data-group-id="2490351793-2">]</span><span class="w">
│ │ │ -</span><span class="nf">record_info</span><span class="p" data-group-id="2490351793-3">(</span><span class="nb">size</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="2490351793-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Size</span></code></pre><p><code class="inline">Size</code> is the size of the tuple representation, that is, one more than the
│ │ │ +record defined as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7884278837-1">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7884278837-2">{</span><span class="n">Field1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">FieldN</span><span class="p" data-group-id="7884278837-2">}</span><span class="p" data-group-id="7884278837-1">)</span><span class="p">.</span></code></pre><p>is internally represented by the tuple:</p><pre><code class="text">{Name, Value1, ..., ValueN}</code></pre><p>Here each <code class="inline">ValueI</code> is the default value for <code class="inline">FieldI</code>.</p><p>To each module using records, a pseudo function is added during compilation to
│ │ │ +obtain information about records:</p><pre><code class="makeup erlang" translate="no"><span class="nf">record_info</span><span class="p" data-group-id="0024103994-1">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="0024103994-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0024103994-2">[</span><span class="n">Field</span><span class="p" data-group-id="0024103994-2">]</span><span class="w">
│ │ │ +</span><span class="nf">record_info</span><span class="p" data-group-id="0024103994-3">(</span><span class="nb">size</span><span class="p">,</span><span class="w"> </span><span class="n">Record</span><span class="p" data-group-id="0024103994-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Size</span></code></pre><p><code class="inline">Size</code> is the size of the tuple representation, that is, one more than the
│ │ │  number of fields.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="macros.html" class="bottom-actions-button" rel="prev">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/release_handling.html
│ │ │ @@ -223,38 +223,38 @@
│ │ │    <span class="text">update</span>
│ │ │  </h3>
│ │ │  <p>If a more complex change has been made, for example, a change to the format of
│ │ │  the internal state of a <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html"><code class="inline">gen_server</code></a>, simple code replacement is not sufficient.
│ │ │  Instead, it is necessary to:</p><ul><li>Suspend the processes using the module (to avoid that they try to handle any
│ │ │  requests before the code replacement is completed).</li><li>Ask them to transform the internal state format and switch to the new version
│ │ │  of the module.</li><li>Remove the old version.</li><li>Resume the processes.</li></ul><p>This is called <em>synchronized code replacement</em> and for this the following
│ │ │ -instructions are used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3578876522-1">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3578876522-2">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="3578876522-2">}</span><span class="p" data-group-id="3578876522-1">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3578876522-3">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="3578876522-3">}</span></code></pre><p><code class="inline">update</code> with argument <code class="inline">{advanced,Extra}</code> is used when changing the internal
│ │ │ +instructions are used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8759583972-1">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8759583972-2">{</span><span class="ss">advanced</span><span class="p">,</span><span class="w"> </span><span class="n">Extra</span><span class="p" data-group-id="8759583972-2">}</span><span class="p" data-group-id="8759583972-1">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8759583972-3">{</span><span class="ss">update</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="8759583972-3">}</span></code></pre><p><code class="inline">update</code> with argument <code class="inline">{advanced,Extra}</code> is used when changing the internal
│ │ │  state of a behaviour as described above. It causes behaviour processes to call
│ │ │  the callback function <code class="inline">code_change/3</code>, passing the term <code class="inline">Extra</code> and some other
│ │ │  information as arguments. See the manual pages for the respective behaviours and
│ │ │  <a href="appup_cookbook.html#int_state">Appup Cookbook</a>.</p><p><code class="inline">update</code> with argument <code class="inline">supervisor</code> is used when changing the start
│ │ │  specification of a supervisor. See <a href="appup_cookbook.html#sup">Appup Cookbook</a>.</p><p>When a module is to be updated, the release handler finds which processes that
│ │ │  are <em>using</em> the module by traversing the supervision tree of each running
│ │ │ -application and checking all the child specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8358288597-1">{</span><span class="n">Id</span><span class="p">,</span><span class="w"> </span><span class="n">StartFunc</span><span class="p">,</span><span class="w"> </span><span class="n">Restart</span><span class="p">,</span><span class="w"> </span><span class="n">Shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Modules</span><span class="p" data-group-id="8358288597-1">}</span></code></pre><p>A process uses a module if the name is listed in <code class="inline">Modules</code> in the child
│ │ │ +application and checking all the child specifications:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0256177256-1">{</span><span class="n">Id</span><span class="p">,</span><span class="w"> </span><span class="n">StartFunc</span><span class="p">,</span><span class="w"> </span><span class="n">Restart</span><span class="p">,</span><span class="w"> </span><span class="n">Shutdown</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Modules</span><span class="p" data-group-id="0256177256-1">}</span></code></pre><p>A process uses a module if the name is listed in <code class="inline">Modules</code> in the child
│ │ │  specification for the process.</p><p>If <code class="inline">Modules=dynamic</code>, which is the case for event managers, the event manager
│ │ │  process informs the release handler about the list of currently installed event
│ │ │  handlers (<code class="inline">gen_event</code>), and it is checked if the module name is in this list
│ │ │  instead.</p><p>The release handler suspends, asks for code change, and resumes processes by
│ │ │  calling the functions <code class="inline">sys:suspend/1,2</code>, <code class="inline">sys:change_code/4,5</code>, and
│ │ │  <code class="inline">sys:resume/1,2</code>, respectively.</p><h3 id="add_module-and-delete_module" class="section-heading">
│ │ │    <a href="#add_module-and-delete_module" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">add_module and delete_module</span>
│ │ │  </h3>
│ │ │ -<p>If a new module is introduced, the following instruction is used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3202319590-1">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="3202319590-1">}</span></code></pre><p>This instruction loads module <code class="inline">Module</code>. When running Erlang in
│ │ │ +<p>If a new module is introduced, the following instruction is used:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2598946827-1">{</span><span class="ss">add_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="2598946827-1">}</span></code></pre><p>This instruction loads module <code class="inline">Module</code>. When running Erlang in
│ │ │  embedded mode it is necessary to use this this instruction. It is not
│ │ │  strictly required when running Erlang in interactive mode, since the
│ │ │ -code server automatically searches for and loads unloaded modules.</p><p>The opposite of <code class="inline">add_module</code> is <code class="inline">delete_module</code>, which unloads a module:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0701222701-1">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="0701222701-1">}</span></code></pre><p>Any process, in any application, with <code class="inline">Module</code> as residence module, is
│ │ │ +code server automatically searches for and loads unloaded modules.</p><p>The opposite of <code class="inline">add_module</code> is <code class="inline">delete_module</code>, which unloads a module:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0959770347-1">{</span><span class="nb">delete_module</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="0959770347-1">}</span></code></pre><p>Any process, in any application, with <code class="inline">Module</code> as residence module, is
│ │ │  killed when the instruction is evaluated. Therefore, the user must
│ │ │  ensure that all such processes are terminated before deleting module
│ │ │  <code class="inline">Module</code> to avoid a situation with failing supervisor restarts.</p><h3 id="application-instructions" class="section-heading">
│ │ │    <a href="#application-instructions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Application Instructions</span>
│ │ │ @@ -341,60 +341,60 @@
│ │ │  <code class="inline">.app</code> file.</li><li>Each <code class="inline">UpFromVsn</code> is a previous version of the application to upgrade from.</li><li>Each <code class="inline">DownToVsn</code> is a previous version of the application to downgrade to.</li><li>Each <code class="inline">Instructions</code> is a list of release handling instructions.</li></ul><p><code class="inline">UpFromVsn</code> and <code class="inline">DownToVsn</code> can also be specified as regular expressions. For
│ │ │  more information about the syntax and contents of the <code class="inline">.appup</code> file, see
│ │ │  <a href="../../lib/sasl-4.2.2/doc/html/appup.html"><code class="inline">appup</code></a> in SASL.</p><p><a href="appup_cookbook.html">Appup Cookbook</a> includes examples of <code class="inline">.appup</code> files for
│ │ │  typical upgrade/downgrade cases.</p><p><em>Example:</em> Consider the release <code class="inline">ch_rel-1</code> from
│ │ │  <a href="release_structure.html#ch_rel">Releases</a>. Assume you want to add a function
│ │ │  <code class="inline">available/0</code> to server <code class="inline">ch3</code>, which returns the number of available channels
│ │ │  (when trying out the example, make the change in a copy of the original
│ │ │ -directory, to ensure that the first version is still available):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3096614519-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="3096614519-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="3096614519-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="3096614519-2">)</span><span class="p">.</span><span class="w">
│ │ │ +directory, to ensure that the first version is still available):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8585816592-1">(</span><span class="ss">ch3</span><span class="p" data-group-id="8585816592-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="8585816592-2">(</span><span class="ss">gen_server</span><span class="p" data-group-id="8585816592-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3096614519-3">(</span><span class="p" data-group-id="3096614519-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3096614519-4">]</span><span class="p" data-group-id="3096614519-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3096614519-5">(</span><span class="p" data-group-id="3096614519-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3096614519-6">]</span><span class="p" data-group-id="3096614519-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3096614519-7">(</span><span class="p" data-group-id="3096614519-8">[</span><span class="ss">available</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3096614519-8">]</span><span class="p" data-group-id="3096614519-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3096614519-9">(</span><span class="p" data-group-id="3096614519-10">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="3096614519-10">]</span><span class="p" data-group-id="3096614519-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8585816592-3">(</span><span class="p" data-group-id="8585816592-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8585816592-4">]</span><span class="p" data-group-id="8585816592-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8585816592-5">(</span><span class="p" data-group-id="8585816592-6">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8585816592-6">]</span><span class="p" data-group-id="8585816592-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8585816592-7">(</span><span class="p" data-group-id="8585816592-8">[</span><span class="ss">available</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8585816592-8">]</span><span class="p" data-group-id="8585816592-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8585816592-9">(</span><span class="p" data-group-id="8585816592-10">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_call</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_cast</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8585816592-10">]</span><span class="p" data-group-id="8585816592-9">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="3096614519-11">(</span><span class="p" data-group-id="3096614519-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3096614519-12">(</span><span class="p" data-group-id="3096614519-13">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3096614519-13">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3096614519-14">[</span><span class="p" data-group-id="3096614519-14">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3096614519-15">[</span><span class="p" data-group-id="3096614519-15">]</span><span class="p" data-group-id="3096614519-12">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="8585816592-11">(</span><span class="p" data-group-id="8585816592-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8585816592-12">(</span><span class="p" data-group-id="8585816592-13">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="8585816592-13">}</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8585816592-14">[</span><span class="p" data-group-id="8585816592-14">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8585816592-15">[</span><span class="p" data-group-id="8585816592-15">]</span><span class="p" data-group-id="8585816592-12">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="3096614519-16">(</span><span class="p" data-group-id="3096614519-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="3096614519-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="3096614519-17">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="8585816592-16">(</span><span class="p" data-group-id="8585816592-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="8585816592-17">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="8585816592-17">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="3096614519-18">(</span><span class="n">Ch</span><span class="p" data-group-id="3096614519-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="3096614519-19">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3096614519-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3096614519-20">}</span><span class="p" data-group-id="3096614519-19">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="8585816592-18">(</span><span class="n">Ch</span><span class="p" data-group-id="8585816592-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="8585816592-19">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8585816592-20">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8585816592-20">}</span><span class="p" data-group-id="8585816592-19">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">available</span><span class="p" data-group-id="3096614519-21">(</span><span class="p" data-group-id="3096614519-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="3096614519-22">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">available</span><span class="p" data-group-id="3096614519-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">available</span><span class="p" data-group-id="8585816592-21">(</span><span class="p" data-group-id="8585816592-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_server</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="8585816592-22">(</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">available</span><span class="p" data-group-id="8585816592-22">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3096614519-23">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="3096614519-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3096614519-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="3096614519-25">(</span><span class="p" data-group-id="3096614519-25">)</span><span class="p" data-group-id="3096614519-24">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="8585816592-23">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="8585816592-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8585816592-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="8585816592-25">(</span><span class="p" data-group-id="8585816592-25">)</span><span class="p" data-group-id="8585816592-24">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="3096614519-26">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3096614519-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3096614519-27">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3096614519-27">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="3096614519-28">(</span><span class="n">Chs</span><span class="p" data-group-id="3096614519-28">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3096614519-29">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3096614519-29">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_call</span><span class="p" data-group-id="3096614519-30">(</span><span class="ss">available</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3096614519-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">available</span><span class="p" data-group-id="3096614519-31">(</span><span class="n">Chs</span><span class="p" data-group-id="3096614519-31">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3096614519-32">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3096614519-32">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="8585816592-26">(</span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8585816592-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8585816592-27">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="8585816592-27">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="8585816592-28">(</span><span class="n">Chs</span><span class="p" data-group-id="8585816592-28">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8585816592-29">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="8585816592-29">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_call</span><span class="p" data-group-id="8585816592-30">(</span><span class="ss">available</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8585816592-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">available</span><span class="p" data-group-id="8585816592-31">(</span><span class="n">Chs</span><span class="p" data-group-id="8585816592-31">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8585816592-32">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8585816592-32">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_cast</span><span class="p" data-group-id="3096614519-33">(</span><span class="p" data-group-id="3096614519-34">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="3096614519-34">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3096614519-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="3096614519-35">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="3096614519-35">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3096614519-36">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="3096614519-36">}</span><span class="p">.</span></code></pre><p>A new version of the <code class="inline">ch_app.app</code> file must now be created, where the version is
│ │ │ -updated:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5156739451-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5156739451-2">[</span><span class="p" data-group-id="5156739451-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="5156739451-3">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5156739451-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="5156739451-4">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5156739451-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5156739451-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="5156739451-6">]</span><span class="p" data-group-id="5156739451-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5156739451-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5156739451-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="5156739451-8">]</span><span class="p" data-group-id="5156739451-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5156739451-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5156739451-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="5156739451-10">]</span><span class="p" data-group-id="5156739451-9">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5156739451-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5156739451-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="5156739451-13">[</span><span class="p" data-group-id="5156739451-13">]</span><span class="p" data-group-id="5156739451-12">}</span><span class="p" data-group-id="5156739451-11">}</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5156739451-2">]</span><span class="p" data-group-id="5156739451-1">}</span><span class="p">.</span></code></pre><p>To upgrade <code class="inline">ch_app</code> from <code class="inline">&quot;1&quot;</code> to <code class="inline">&quot;2&quot;</code> (and to downgrade from <code class="inline">&quot;2&quot;</code> to <code class="inline">&quot;1&quot;</code>),
│ │ │ +</span><span class="nf">handle_cast</span><span class="p" data-group-id="8585816592-33">(</span><span class="p" data-group-id="8585816592-34">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8585816592-34">}</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8585816592-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="8585816592-35">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8585816592-35">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8585816592-36">{</span><span class="ss">noreply</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="8585816592-36">}</span><span class="p">.</span></code></pre><p>A new version of the <code class="inline">ch_app.app</code> file must now be created, where the version is
│ │ │ +updated:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3648689718-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3648689718-2">[</span><span class="p" data-group-id="3648689718-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="3648689718-3">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3648689718-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="3648689718-4">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3648689718-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3648689718-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="3648689718-6">]</span><span class="p" data-group-id="3648689718-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3648689718-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3648689718-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="3648689718-8">]</span><span class="p" data-group-id="3648689718-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3648689718-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3648689718-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="3648689718-10">]</span><span class="p" data-group-id="3648689718-9">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3648689718-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3648689718-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="3648689718-13">[</span><span class="p" data-group-id="3648689718-13">]</span><span class="p" data-group-id="3648689718-12">}</span><span class="p" data-group-id="3648689718-11">}</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3648689718-2">]</span><span class="p" data-group-id="3648689718-1">}</span><span class="p">.</span></code></pre><p>To upgrade <code class="inline">ch_app</code> from <code class="inline">&quot;1&quot;</code> to <code class="inline">&quot;2&quot;</code> (and to downgrade from <code class="inline">&quot;2&quot;</code> to <code class="inline">&quot;1&quot;</code>),
│ │ │  you only need to load the new (old) version of the <code class="inline">ch3</code> callback module. Create
│ │ │ -the application upgrade file <code class="inline">ch_app.appup</code> in the <code class="inline">ebin</code> directory:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6371134580-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="6371134580-2">[</span><span class="p" data-group-id="6371134580-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6371134580-4">[</span><span class="p" data-group-id="6371134580-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="6371134580-5">}</span><span class="p" data-group-id="6371134580-4">]</span><span class="p" data-group-id="6371134580-3">}</span><span class="p" data-group-id="6371134580-2">]</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="6371134580-6">[</span><span class="p" data-group-id="6371134580-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6371134580-8">[</span><span class="p" data-group-id="6371134580-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="6371134580-9">}</span><span class="p" data-group-id="6371134580-8">]</span><span class="p" data-group-id="6371134580-7">}</span><span class="p" data-group-id="6371134580-6">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6371134580-1">}</span><span class="p">.</span></code></pre><p><a href="" id="relup"></a></p><h2 id="release-upgrade-file" class="section-heading">
│ │ │ +the application upgrade file <code class="inline">ch_app.appup</code> in the <code class="inline">ebin</code> directory:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4585985845-1">{</span><span class="s">&quot;2&quot;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="4585985845-2">[</span><span class="p" data-group-id="4585985845-3">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4585985845-4">[</span><span class="p" data-group-id="4585985845-5">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="4585985845-5">}</span><span class="p" data-group-id="4585985845-4">]</span><span class="p" data-group-id="4585985845-3">}</span><span class="p" data-group-id="4585985845-2">]</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="4585985845-6">[</span><span class="p" data-group-id="4585985845-7">{</span><span class="s">&quot;1&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4585985845-8">[</span><span class="p" data-group-id="4585985845-9">{</span><span class="nb">load_module</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="4585985845-9">}</span><span class="p" data-group-id="4585985845-8">]</span><span class="p" data-group-id="4585985845-7">}</span><span class="p" data-group-id="4585985845-6">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4585985845-1">}</span><span class="p">.</span></code></pre><p><a href="" id="relup"></a></p><h2 id="release-upgrade-file" class="section-heading">
│ │ │    <a href="#release-upgrade-file" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Release Upgrade File</span>
│ │ │  </h2>
│ │ │  <p>To define how to upgrade/downgrade between the new version and previous versions
│ │ │  of a release, a <em>release upgrade file</em>, or in short <code class="inline">.relup</code> file, is to be
│ │ │ @@ -405,22 +405,22 @@
│ │ │  are to be added and deleted, and which applications that must be upgraded and/or
│ │ │  downgraded. The instructions for this are fetched from the <code class="inline">.appup</code> files and
│ │ │  transformed into a single list of low-level instructions in the right order.</p><p>If the <code class="inline">relup</code> file is relatively simple, it can be created manually. It is only
│ │ │  to contain low-level instructions.</p><p>For details about the syntax and contents of the release upgrade file, see
│ │ │  <a href="../../lib/sasl-4.2.2/doc/html/relup.html"><code class="inline">relup</code></a> in SASL.</p><p><em>Example, continued from the previous section:</em> You have a new version &quot;2&quot; of
│ │ │  <code class="inline">ch_app</code> and an <code class="inline">.appup</code> file. A new version of the <code class="inline">.rel</code> file is also needed.
│ │ │  This time the file is called <code class="inline">ch_rel-2.rel</code> and the release version string is
│ │ │ -changed from &quot;A&quot; to &quot;B&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5013001279-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5013001279-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="5013001279-2">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5013001279-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="5013001279-3">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="5013001279-4">[</span><span class="p" data-group-id="5013001279-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="5013001279-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5013001279-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="5013001279-6">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5013001279-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="5013001279-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="5013001279-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="5013001279-8">}</span><span class="p" data-group-id="5013001279-4">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5013001279-1">}</span><span class="p">.</span></code></pre><p>Now the <code class="inline">relup</code> file can be generated:</p><pre><code class="text">1&gt; systools:make_relup(&quot;ch_rel-2&quot;, [&quot;ch_rel-1&quot;], [&quot;ch_rel-1&quot;]).
│ │ │ +changed from &quot;A&quot; to &quot;B&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5911395100-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5911395100-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="5911395100-2">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5911395100-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="5911395100-3">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5911395100-4">[</span><span class="p" data-group-id="5911395100-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="5911395100-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5911395100-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="5911395100-6">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5911395100-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="5911395100-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="5911395100-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;2&quot;</span><span class="p" data-group-id="5911395100-8">}</span><span class="p" data-group-id="5911395100-4">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5911395100-1">}</span><span class="p">.</span></code></pre><p>Now the <code class="inline">relup</code> file can be generated:</p><pre><code class="text">1&gt; systools:make_relup(&quot;ch_rel-2&quot;, [&quot;ch_rel-1&quot;], [&quot;ch_rel-1&quot;]).
│ │ │  ok</code></pre><p>This generates a <code class="inline">relup</code> file with instructions for how to upgrade from version
│ │ │  &quot;A&quot; (&quot;ch_rel-1&quot;) to version &quot;B&quot; (&quot;ch_rel-2&quot;) and how to downgrade from version
│ │ │  &quot;B&quot; to version &quot;A&quot;.</p><p>Both the old and new versions of the <code class="inline">.app</code> and <code class="inline">.rel</code> files must be in the code
│ │ │  path, as well as the <code class="inline">.appup</code> and (new) <code class="inline">.beam</code> files. The code path can be
│ │ │  extended by using the option <code class="inline">path</code>:</p><pre><code class="text">1&gt; systools:make_relup(&quot;ch_rel-2&quot;, [&quot;ch_rel-1&quot;], [&quot;ch_rel-1&quot;],
│ │ │  [{path,[&quot;../ch_rel-1&quot;,
│ │ │  &quot;../ch_rel-1/lib/ch_app-1/ebin&quot;]}]).
│ │ │ @@ -433,25 +433,25 @@
│ │ │  <p>When you have made a new version of a release, a release package can be created
│ │ │  with this new version and transferred to the target environment.</p><p>To install the new version of the release in runtime, the <em>release
│ │ │  handler</em> is used. This is a process belonging to the SASL application,
│ │ │  which handles unpacking, installation, and removal of release
│ │ │  packages. The <a href="../../lib/sasl-4.2.2/doc/html/release_handler.html"><code class="inline">release_handler</code></a> module communicates with this process.</p><p>Assuming there is an operational target system with installation root directory
│ │ │  <code class="inline">$ROOT</code>, the release package with the new version of the release is to be copied
│ │ │  to <code class="inline">$ROOT/releases</code>.</p><p>First, <em>unpack</em> the release package. The files are then extracted from the
│ │ │ -package:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="7070845043-1">(</span><span class="n">ReleaseName</span><span class="p" data-group-id="7070845043-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7070845043-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p" data-group-id="7070845043-2">}</span></code></pre><ul><li><code class="inline">ReleaseName</code> is the name of the release package except the <code class="inline">.tar.gz</code>
│ │ │ +package:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="7572895657-1">(</span><span class="n">ReleaseName</span><span class="p" data-group-id="7572895657-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7572895657-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p" data-group-id="7572895657-2">}</span></code></pre><ul><li><code class="inline">ReleaseName</code> is the name of the release package except the <code class="inline">.tar.gz</code>
│ │ │  extension.</li><li><code class="inline">Vsn</code> is the version of the unpacked release, as defined in its <code class="inline">.rel</code> file.</li></ul><p>A directory <code class="inline">$ROOT/lib/releases/Vsn</code> is created, where the <code class="inline">.rel</code> file, the boot
│ │ │  script <code class="inline">start.boot</code>, the system configuration file <code class="inline">sys.config</code>, and <code class="inline">relup</code> are
│ │ │  placed. For applications with new version numbers, the application directories
│ │ │  are placed under <code class="inline">$ROOT/lib</code>. Unchanged applications are not affected.</p><p>An unpacked release can be <em>installed</em>. The release handler then evaluates the
│ │ │ -instructions in <code class="inline">relup</code>, step by step:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="4560317961-1">(</span><span class="n">Vsn</span><span class="p" data-group-id="4560317961-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4560317961-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FromVsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4560317961-3">[</span><span class="p" data-group-id="4560317961-3">]</span><span class="p" data-group-id="4560317961-2">}</span></code></pre><p>If an error occurs during the installation, the system is rebooted using the old
│ │ │ +instructions in <code class="inline">relup</code>, step by step:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="0615723700-1">(</span><span class="n">Vsn</span><span class="p" data-group-id="0615723700-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0615723700-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">FromVsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0615723700-3">[</span><span class="p" data-group-id="0615723700-3">]</span><span class="p" data-group-id="0615723700-2">}</span></code></pre><p>If an error occurs during the installation, the system is rebooted using the old
│ │ │  version of the release. If installation succeeds, the system is afterwards using
│ │ │  the new version of the release, but if anything happens and the system is
│ │ │  rebooted, it starts using the previous version again.</p><p>To be made the default version, the newly installed release must be made
│ │ │  <em>permanent</em>, which means the previous version becomes <em>old</em>:</p><pre><code class="text">release_handler:make_permanent(Vsn) =&gt; ok</code></pre><p>The system keeps information about which versions are old and permanent in the
│ │ │ -files <code class="inline">$ROOT/releases/RELEASES</code> and <code class="inline">$ROOT/releases/start_erl.data</code>.</p><p>To downgrade from <code class="inline">Vsn</code> to <code class="inline">FromVsn</code>, <code class="inline">install_release</code> must be called again:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="2501724387-1">(</span><span class="n">FromVsn</span><span class="p" data-group-id="2501724387-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2501724387-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2501724387-3">[</span><span class="p" data-group-id="2501724387-3">]</span><span class="p" data-group-id="2501724387-2">}</span></code></pre><p>An installed, but not permanent, release can be <em>removed</em>. Information about the
│ │ │ +files <code class="inline">$ROOT/releases/RELEASES</code> and <code class="inline">$ROOT/releases/start_erl.data</code>.</p><p>To downgrade from <code class="inline">Vsn</code> to <code class="inline">FromVsn</code>, <code class="inline">install_release</code> must be called again:</p><pre><code class="makeup erlang" translate="no"><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="4434709343-1">(</span><span class="n">FromVsn</span><span class="p" data-group-id="4434709343-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4434709343-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Vsn</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4434709343-3">[</span><span class="p" data-group-id="4434709343-3">]</span><span class="p" data-group-id="4434709343-2">}</span></code></pre><p>An installed, but not permanent, release can be <em>removed</em>. Information about the
│ │ │  release is then deleted from <code class="inline">$ROOT/releases/RELEASES</code> and the release-specific
│ │ │  code, that is, the new application directories and the <code class="inline">$ROOT/releases/Vsn</code>
│ │ │  directory, are removed.</p><pre><code class="text">release_handler:remove_release(Vsn) =&gt; ok</code></pre><h3 id="example-continued-from-the-previous-sections" class="section-heading">
│ │ │    <a href="#example-continued-from-the-previous-sections" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Example (continued from the previous sections)</span>
│ │ │ @@ -462,17 +462,17 @@
│ │ │  is needed, the file is to contain the empty list:</p><pre><code class="text">[].</code></pre><p><em>Step 2)</em> Start the system as a simple target system. In reality, it is to be
│ │ │  started as an embedded system. However, using <code class="inline">erl</code> with the correct boot script
│ │ │  and config file is enough for illustration purposes:</p><pre><code class="text">% cd $ROOT
│ │ │  % bin/erl -boot $ROOT/releases/A/start -config $ROOT/releases/A/sys
│ │ │  ...</code></pre><p><code class="inline">$ROOT</code> is the installation directory of the target system.</p><p><em>Step 3)</em> In another Erlang shell, generate start scripts and create a release
│ │ │  package for the new version <code class="inline">&quot;B&quot;</code>. Remember to include (a possible updated)
│ │ │  <code class="inline">sys.config</code> and the <code class="inline">relup</code> file. For more information, see
│ │ │ -<a href="release_handling.html#relup">Release Upgrade File</a>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="4973883834-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="4973883834-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<a href="release_handling.html#relup">Release Upgrade File</a>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="0440130119-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="0440130119-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="4973883834-2">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="4973883834-2">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="0440130119-2">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="0440130119-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>The new release package now also contains version &quot;2&quot; of <code class="inline">ch_app</code> and the
│ │ │  <code class="inline">relup</code> file:</p><pre><code class="text">% tar tf ch_rel-2.tar
│ │ │  lib/kernel-9.2.4/ebin/kernel.app
│ │ │  lib/kernel-9.2.4/ebin/application.beam
│ │ │  ...
│ │ │  lib/stdlib-5.2.3/ebin/stdlib.app
│ │ │  lib/stdlib-5.2.3/ebin/argparse.beam
│ │ │ @@ -485,31 +485,31 @@
│ │ │  lib/ch_app-2/ebin/ch_sup.beam
│ │ │  lib/ch_app-2/ebin/ch3.beam
│ │ │  releases/B/start.boot
│ │ │  releases/B/relup
│ │ │  releases/B/sys.config
│ │ │  releases/B/ch_rel-2.rel
│ │ │  releases/ch_rel-2.rel</code></pre><p><em>Step 4)</em> Copy the release package <code class="inline">ch_rel-2.tar.gz</code> to the <code class="inline">$ROOT/releases</code>
│ │ │ -directory.</p><p><em>Step 5)</em> In the running target system, unpack the release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="0627269114-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="0627269114-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0627269114-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="0627269114-2">}</span></code></pre><p>The new application version <code class="inline">ch_app-2</code> is installed under <code class="inline">$ROOT/lib</code> next to
│ │ │ +directory.</p><p><em>Step 5)</em> In the running target system, unpack the release package:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">unpack_release</span><span class="p" data-group-id="0760806897-1">(</span><span class="s">&quot;ch_rel-2&quot;</span><span class="p" data-group-id="0760806897-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0760806897-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="0760806897-2">}</span></code></pre><p>The new application version <code class="inline">ch_app-2</code> is installed under <code class="inline">$ROOT/lib</code> next to
│ │ │  <code class="inline">ch_app-1</code>. The <code class="inline">kernel</code>, <code class="inline">stdlib</code>, and <code class="inline">sasl</code> directories are not affected, as
│ │ │  they have not changed.</p><p>Under <code class="inline">$ROOT/releases</code>, a new directory <code class="inline">B</code> is created, containing
│ │ │ -<code class="inline">ch_rel-2.rel</code>, <code class="inline">start.boot</code>, <code class="inline">sys.config</code>, and <code class="inline">relup</code>.</p><p><em>Step 6)</em> Check if the function <code class="inline">ch3:available/0</code> is available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="0040081079-1">(</span><span class="p" data-group-id="0040081079-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">ch_rel-2.rel</code>, <code class="inline">start.boot</code>, <code class="inline">sys.config</code>, and <code class="inline">relup</code>.</p><p><em>Step 6)</em> Check if the function <code class="inline">ch3:available/0</code> is available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="1684224949-1">(</span><span class="p" data-group-id="1684224949-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: undefined function ch3:available/0</span></code></pre><p><em>Step 7)</em> Install the new release. The instructions in <code class="inline">$ROOT/releases/B/relup</code>
│ │ │  are executed one by one, resulting in the new version of <code class="inline">ch3</code> being loaded. The
│ │ │ -function <code class="inline">ch3:available/0</code> is now available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="3882401716-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="3882401716-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3882401716-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="p" data-group-id="3882401716-3">[</span><span class="p" data-group-id="3882401716-3">]</span><span class="p" data-group-id="3882401716-2">}</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="3882401716-4">(</span><span class="p" data-group-id="3882401716-4">)</span><span class="p">.</span><span class="w">
│ │ │ +function <code class="inline">ch3:available/0</code> is now available:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">install_release</span><span class="p" data-group-id="9106854256-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="9106854256-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9106854256-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="s">&quot;A&quot;</span><span class="p">,</span><span class="p" data-group-id="9106854256-3">[</span><span class="p" data-group-id="9106854256-3">]</span><span class="p" data-group-id="9106854256-2">}</span><span class="gp unselectable">
│ │ │ +4&gt; </span><span class="nc">ch3</span><span class="p">:</span><span class="nf">available</span><span class="p" data-group-id="9106854256-4">(</span><span class="p" data-group-id="9106854256-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="3882401716-5">(</span><span class="ss">ch3</span><span class="p" data-group-id="3882401716-5">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="9106854256-5">(</span><span class="ss">ch3</span><span class="p" data-group-id="9106854256-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;.../lib/ch_app-2/ebin/ch3.beam&quot;</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="3882401716-6">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="3882401716-6">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="nc">code</span><span class="p">:</span><span class="nf">which</span><span class="p" data-group-id="9106854256-6">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="9106854256-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;.../lib/ch_app-1/ebin/ch_sup.beam&quot;</span></code></pre><p>Processes in <code class="inline">ch_app</code> for which code have not been updated, for example, the
│ │ │  supervisor, are still evaluating code from <code class="inline">ch_app-1</code>.</p><p><em>Step 8)</em> If the target system is now rebooted, it uses version &quot;A&quot; again. The
│ │ │ -&quot;B&quot; version must be made permanent, to be used when the system is rebooted.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">make_permanent</span><span class="p" data-group-id="4057212511-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="4057212511-1">)</span><span class="p">.</span><span class="w">
│ │ │ +&quot;B&quot; version must be made permanent, to be used when the system is rebooted.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nc">release_handler</span><span class="p">:</span><span class="nf">make_permanent</span><span class="p" data-group-id="1198997629-1">(</span><span class="s">&quot;B&quot;</span><span class="p" data-group-id="1198997629-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p><a href="" id="sys"></a></p><h2 id="updating-application-specifications" class="section-heading">
│ │ │    <a href="#updating-application-specifications" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Updating Application Specifications</span>
│ │ │  </h2>
│ │ │  <p>When a new version of a release is installed, the application specifications are
│ │ │ @@ -518,15 +518,15 @@
│ │ │  boot script is generated from the same <code class="inline">.rel</code> file as is used to build the
│ │ │  release package itself.</p></section><p>Specifically, the application configuration parameters are automatically updated
│ │ │  according to (in increasing priority order):</p><ul><li>The data in the boot script, fetched from the new application resource file
│ │ │  <code class="inline">App.app</code></li><li>The new <code class="inline">sys.config</code></li><li>Command-line arguments <code class="inline">-App Par Val</code></li></ul><p>This means that parameter values set in the other system configuration files and
│ │ │  values set using <a href="../../lib/kernel-10.2.7.2/doc/html/application.html#set_env/3"><code class="inline">application:set_env/3</code></a> are disregarded.</p><p>When an installed release is made permanent, the system process <code class="inline">init</code> is set to
│ │ │  point out the new <code class="inline">sys.config</code>.</p><p>After the installation, the application controller compares the old and new
│ │ │  configuration parameters for all running applications and call the callback
│ │ │ -function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">config_change</span><span class="p" data-group-id="8685816765-1">(</span><span class="n">Changed</span><span class="p">,</span><span class="w"> </span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">Removed</span><span class="p" data-group-id="8685816765-1">)</span></code></pre><ul><li><code class="inline">Module</code> is the application callback module as defined by the <code class="inline">mod</code> key in the
│ │ │ +function:</p><pre><code class="makeup erlang" translate="no"><span class="n">Module</span><span class="p">:</span><span class="nf">config_change</span><span class="p" data-group-id="1742676972-1">(</span><span class="n">Changed</span><span class="p">,</span><span class="w"> </span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">Removed</span><span class="p" data-group-id="1742676972-1">)</span></code></pre><ul><li><code class="inline">Module</code> is the application callback module as defined by the <code class="inline">mod</code> key in the
│ │ │  <code class="inline">.app</code> file.</li><li><code class="inline">Changed</code> and <code class="inline">New</code> are lists of <code class="inline">{Par,Val}</code> for all changed and added
│ │ │  configuration parameters, respectively.</li><li><code class="inline">Removed</code> is a list of all parameters <code class="inline">Par</code> that have been removed.</li></ul><p>The function is optional and can be omitted when implementing an application
│ │ │  callback module.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/release_structure.html
│ │ │ @@ -136,37 +136,37 @@
│ │ │    <a href="#release-resource-file" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Release Resource File</span>
│ │ │  </h2>
│ │ │  <p>To define a release, create a <em>release resource file</em>, or in short a <code class="inline">.rel</code>
│ │ │  file. In the file, specify the name and version of the release, which ERTS
│ │ │ -version it is based on, and which applications it consists of:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9445835917-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9445835917-2">{</span><span class="n">Name</span><span class="p">,</span><span class="n">Vsn</span><span class="p" data-group-id="9445835917-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9445835917-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">EVsn</span><span class="p" data-group-id="9445835917-3">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9445835917-4">[</span><span class="p" data-group-id="9445835917-5">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsn1</span><span class="p" data-group-id="9445835917-5">}</span><span class="p">,</span><span class="w">
│ │ │ +version it is based on, and which applications it consists of:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7997583570-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7997583570-2">{</span><span class="n">Name</span><span class="p">,</span><span class="n">Vsn</span><span class="p" data-group-id="7997583570-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7997583570-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="n">EVsn</span><span class="p" data-group-id="7997583570-3">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7997583570-4">[</span><span class="p" data-group-id="7997583570-5">{</span><span class="n">Application1</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsn1</span><span class="p" data-group-id="7997583570-5">}</span><span class="p">,</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9445835917-6">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsnN</span><span class="p" data-group-id="9445835917-6">}</span><span class="p" data-group-id="9445835917-4">]</span><span class="p" data-group-id="9445835917-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Name</code>, <code class="inline">Vsn</code>, <code class="inline">EVsn</code>, and <code class="inline">AppVsn</code> are strings.</p><p>The file must be named <code class="inline">Rel.rel</code>, where <code class="inline">Rel</code> is a unique name.</p><p>Each <code class="inline">Application</code> (atom) and <code class="inline">AppVsn</code> is the name and version of an application
│ │ │ +  </span><span class="p" data-group-id="7997583570-6">{</span><span class="n">ApplicationN</span><span class="p">,</span><span class="w"> </span><span class="n">AppVsnN</span><span class="p" data-group-id="7997583570-6">}</span><span class="p" data-group-id="7997583570-4">]</span><span class="p" data-group-id="7997583570-1">}</span><span class="p">.</span></code></pre><p><code class="inline">Name</code>, <code class="inline">Vsn</code>, <code class="inline">EVsn</code>, and <code class="inline">AppVsn</code> are strings.</p><p>The file must be named <code class="inline">Rel.rel</code>, where <code class="inline">Rel</code> is a unique name.</p><p>Each <code class="inline">Application</code> (atom) and <code class="inline">AppVsn</code> is the name and version of an application
│ │ │  included in the release. The minimal release based on Erlang/OTP consists of the
│ │ │  Kernel and STDLIB applications, so these applications must be included in the
│ │ │  list.</p><p>If the release is to be upgraded, it must also include the SASL application.</p><p><a href="" id="ch_rel"></a></p><p>Here is an example showing the <code class="inline">.app</code> file for a release of <code class="inline">ch_app</code> from
│ │ │ -the <a href="applications.html#ch_app">Applications</a> section:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0683144487-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0683144487-2">[</span><span class="p" data-group-id="0683144487-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="0683144487-3">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0683144487-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="0683144487-4">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0683144487-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683144487-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="0683144487-6">]</span><span class="p" data-group-id="0683144487-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0683144487-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683144487-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="0683144487-8">]</span><span class="p" data-group-id="0683144487-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0683144487-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683144487-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="0683144487-10">]</span><span class="p" data-group-id="0683144487-9">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0683144487-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0683144487-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="0683144487-13">[</span><span class="p" data-group-id="0683144487-13">]</span><span class="p" data-group-id="0683144487-12">}</span><span class="p" data-group-id="0683144487-11">}</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0683144487-2">]</span><span class="p" data-group-id="0683144487-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">.rel</code> file must also contain <code class="inline">kernel</code>, <code class="inline">stdlib</code>, and <code class="inline">sasl</code>, as these
│ │ │ -applications are required by <code class="inline">ch_app</code>. The file is called <code class="inline">ch_rel-1.rel</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8796093815-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8796093815-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;A&quot;</span><span class="p" data-group-id="8796093815-2">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8796093815-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="8796093815-3">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8796093815-4">[</span><span class="p" data-group-id="8796093815-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="8796093815-5">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8796093815-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="8796093815-6">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8796093815-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="8796093815-7">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8796093815-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="8796093815-8">}</span><span class="p" data-group-id="8796093815-4">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8796093815-1">}</span><span class="p">.</span></code></pre><p><a href="" id="boot"></a></p><h2 id="generating-boot-scripts" class="section-heading">
│ │ │ +the <a href="applications.html#ch_app">Applications</a> section:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1696818625-1">{</span><span class="ss">application</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_app</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1696818625-2">[</span><span class="p" data-group-id="1696818625-3">{</span><span class="ss">description</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Channel allocator&quot;</span><span class="p" data-group-id="1696818625-3">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1696818625-4">{</span><span class="ss">vsn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="1696818625-4">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1696818625-5">{</span><span class="ss">modules</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1696818625-6">[</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="ss">ch3</span><span class="p" data-group-id="1696818625-6">]</span><span class="p" data-group-id="1696818625-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1696818625-7">{</span><span class="ss">registered</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1696818625-8">[</span><span class="ss">ch3</span><span class="p" data-group-id="1696818625-8">]</span><span class="p" data-group-id="1696818625-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1696818625-9">{</span><span class="ss">applications</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1696818625-10">[</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="ss">sasl</span><span class="p" data-group-id="1696818625-10">]</span><span class="p" data-group-id="1696818625-9">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1696818625-11">{</span><span class="ss">mod</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1696818625-12">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="p" data-group-id="1696818625-13">[</span><span class="p" data-group-id="1696818625-13">]</span><span class="p" data-group-id="1696818625-12">}</span><span class="p" data-group-id="1696818625-11">}</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1696818625-2">]</span><span class="p" data-group-id="1696818625-1">}</span><span class="p">.</span></code></pre><p>The <code class="inline">.rel</code> file must also contain <code class="inline">kernel</code>, <code class="inline">stdlib</code>, and <code class="inline">sasl</code>, as these
│ │ │ +applications are required by <code class="inline">ch_app</code>. The file is called <code class="inline">ch_rel-1.rel</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7408334040-1">{</span><span class="ss">release</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7408334040-2">{</span><span class="s">&quot;ch_rel&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;A&quot;</span><span class="p" data-group-id="7408334040-2">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7408334040-3">{</span><span class="ss">erts</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;14.2.5&quot;</span><span class="p" data-group-id="7408334040-3">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7408334040-4">[</span><span class="p" data-group-id="7408334040-5">{</span><span class="ss">kernel</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;9.2.4&quot;</span><span class="p" data-group-id="7408334040-5">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7408334040-6">{</span><span class="ss">stdlib</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;5.2.3&quot;</span><span class="p" data-group-id="7408334040-6">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7408334040-7">{</span><span class="ss">sasl</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;4.2.1&quot;</span><span class="p" data-group-id="7408334040-7">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7408334040-8">{</span><span class="ss">ch_app</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="7408334040-8">}</span><span class="p" data-group-id="7408334040-4">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7408334040-1">}</span><span class="p">.</span></code></pre><p><a href="" id="boot"></a></p><h2 id="generating-boot-scripts" class="section-heading">
│ │ │    <a href="#generating-boot-scripts" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Generating Boot Scripts</span>
│ │ │  </h2>
│ │ │  <p><a href="../../lib/sasl-4.2.2/doc/html/systools.html"><code class="inline">systools</code></a> in the SASL application includes tools to build and check
│ │ │  releases. The functions read the <code class="inline">.rel</code> and <code class="inline">.app</code> files and perform
│ │ │ @@ -190,17 +190,17 @@
│ │ │    <a href="#creating-a-release-package" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Creating a Release Package</span>
│ │ │  </h2>
│ │ │  <p>The <a href="../../lib/sasl-4.2.2/doc/html/systools.html#make_tar/2"><code class="inline">systools:make_tar/1,2</code></a> function takes a
│ │ │  <code class="inline">.rel</code> file as input and creates a zipped tar file with the code for
│ │ │ -the specified applications, a <em>release package</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="8831504305-1">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="8831504305-1">)</span><span class="p">.</span><span class="w">
│ │ │ +the specified applications, a <em>release package</em>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_script</span><span class="p" data-group-id="9550661237-1">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="9550661237-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="8831504305-2">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="8831504305-2">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="nc">systools</span><span class="p">:</span><span class="nf">make_tar</span><span class="p" data-group-id="9550661237-2">(</span><span class="s">&quot;ch_rel-1&quot;</span><span class="p" data-group-id="9550661237-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>The release package by default contains:</p><ul><li>The <code class="inline">.app</code> files</li><li>The <code class="inline">.rel</code> file</li><li>The object code for all applications, structured according to the
│ │ │  <a href="applications.html#app_dir">application directory structure</a></li><li>The binary boot script renamed to <code class="inline">start.boot</code></li></ul><pre><code class="text">% tar tf ch_rel-1.tar
│ │ │  lib/kernel-9.2.4/ebin/kernel.app
│ │ │  lib/kernel-9.2.4/ebin/application.beam
│ │ │  ...
│ │ │  lib/stdlib-5.2.3/ebin/stdlib.app
│ │ │  lib/stdlib-5.2.3/ebin/argparse.beam
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/robustness.html
│ │ │ @@ -128,68 +128,68 @@
│ │ │  </h2>
│ │ │  <p>Before improving the messenger program, let us look at some general principles,
│ │ │  using the ping pong program as an example. Recall that when &quot;ping&quot; finishes, it
│ │ │  tells &quot;pong&quot; that it has done so by sending the atom <code class="inline">finished</code> as a message to
│ │ │  &quot;pong&quot; so that &quot;pong&quot; can also finish. Another way to let &quot;pong&quot; finish is to
│ │ │  make &quot;pong&quot; exit if it does not receive a message from ping within a certain
│ │ │  time. This can be done by adding a <em>time-out</em> to <code class="inline">pong</code> as shown in the
│ │ │ -following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1340216729-1">(</span><span class="ss">tut19</span><span class="p" data-group-id="1340216729-1">)</span><span class="p">.</span><span class="w">
│ │ │ +following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3707139301-1">(</span><span class="ss">tut19</span><span class="p" data-group-id="3707139301-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1340216729-2">(</span><span class="p" data-group-id="1340216729-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1340216729-3">]</span><span class="p" data-group-id="1340216729-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3707139301-2">(</span><span class="p" data-group-id="3707139301-3">[</span><span class="ss">start_ping</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">start_pong</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3707139301-3">]</span><span class="p" data-group-id="3707139301-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="1340216729-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1340216729-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1340216729-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1340216729-6">[</span><span class="p" data-group-id="1340216729-6">]</span><span class="p" data-group-id="1340216729-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="3707139301-4">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3707139301-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3707139301-5">(</span><span class="s">&quot;ping finished</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3707139301-6">[</span><span class="p" data-group-id="3707139301-6">]</span><span class="p" data-group-id="3707139301-5">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="1340216729-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1340216729-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1340216729-8">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1340216729-8">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1340216729-9">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1340216729-10">(</span><span class="p" data-group-id="1340216729-10">)</span><span class="p" data-group-id="1340216729-9">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="3707139301-7">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3707139301-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3707139301-8">{</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3707139301-8">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="3707139301-9">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3707139301-10">(</span><span class="p" data-group-id="3707139301-10">)</span><span class="p" data-group-id="3707139301-9">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1340216729-11">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1340216729-12">[</span><span class="p" data-group-id="1340216729-12">]</span><span class="p" data-group-id="1340216729-11">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3707139301-11">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3707139301-12">[</span><span class="p" data-group-id="3707139301-12">]</span><span class="p" data-group-id="3707139301-11">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping</span><span class="p" data-group-id="1340216729-13">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1340216729-13">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">ping</span><span class="p" data-group-id="3707139301-13">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3707139301-13">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="1340216729-14">(</span><span class="p" data-group-id="1340216729-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="3707139301-14">(</span><span class="p" data-group-id="3707139301-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="1340216729-15">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="1340216729-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1340216729-16">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1340216729-17">[</span><span class="p" data-group-id="1340216729-17">]</span><span class="p" data-group-id="1340216729-16">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="3707139301-15">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="3707139301-15">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3707139301-16">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3707139301-17">[</span><span class="p" data-group-id="3707139301-17">]</span><span class="p" data-group-id="3707139301-16">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="1340216729-18">(</span><span class="p" data-group-id="1340216729-18">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="3707139301-18">(</span><span class="p" data-group-id="3707139301-18">)</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1340216729-19">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1340216729-20">[</span><span class="p" data-group-id="1340216729-20">]</span><span class="p" data-group-id="1340216729-19">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3707139301-19">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3707139301-20">[</span><span class="p" data-group-id="3707139301-20">]</span><span class="p" data-group-id="3707139301-19">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_pong</span><span class="p" data-group-id="1340216729-21">(</span><span class="p" data-group-id="1340216729-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="1340216729-22">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="1340216729-23">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1340216729-24">[</span><span class="p" data-group-id="1340216729-24">]</span><span class="p" data-group-id="1340216729-23">)</span><span class="p" data-group-id="1340216729-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_pong</span><span class="p" data-group-id="3707139301-21">(</span><span class="p" data-group-id="3707139301-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="3707139301-22">(</span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="3707139301-23">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3707139301-24">[</span><span class="p" data-group-id="3707139301-24">]</span><span class="p" data-group-id="3707139301-23">)</span><span class="p" data-group-id="3707139301-22">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_ping</span><span class="p" data-group-id="1340216729-25">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="1340216729-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="1340216729-26">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1340216729-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="1340216729-27">]</span><span class="p" data-group-id="1340216729-26">)</span><span class="p">.</span></code></pre><p>After this is compiled and the file <code class="inline">tut19.beam</code> is copied to the necessary
│ │ │ +</span><span class="nf">start_ping</span><span class="p" data-group-id="3707139301-25">(</span><span class="n">Pong_Node</span><span class="p" data-group-id="3707139301-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="3707139301-26">(</span><span class="ss">tut19</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3707139301-27">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Node</span><span class="p" data-group-id="3707139301-27">]</span><span class="p" data-group-id="3707139301-26">)</span><span class="p">.</span></code></pre><p>After this is compiled and the file <code class="inline">tut19.beam</code> is copied to the necessary
│ │ │  directories, the following is seen on (pong@kosken):</p><pre><code class="text">(pong@kosken)1&gt; tut19:start_pong().
│ │ │  true
│ │ │  Pong received ping
│ │ │  Pong received ping
│ │ │  Pong received ping
│ │ │  Pong timed out</code></pre><p>And the following is seen on (ping@gollum):</p><pre><code class="text">(ping@gollum)1&gt; tut19:start_ping(pong@kosken).
│ │ │  &lt;0.36.0&gt;
│ │ │  Ping received pong
│ │ │  Ping received pong
│ │ │  Ping received pong
│ │ │ -ping finished</code></pre><p>The time-out is set in:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pong</span><span class="p" data-group-id="6261364803-1">(</span><span class="p" data-group-id="6261364803-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +ping finished</code></pre><p>The time-out is set in:</p><pre><code class="makeup erlang" translate="no"><span class="nf">pong</span><span class="p" data-group-id="3861189639-1">(</span><span class="p" data-group-id="3861189639-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="6261364803-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="6261364803-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6261364803-3">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6261364803-4">[</span><span class="p" data-group-id="6261364803-4">]</span><span class="p" data-group-id="6261364803-3">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="3861189639-2">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="3861189639-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3861189639-3">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3861189639-4">[</span><span class="p" data-group-id="3861189639-4">]</span><span class="p" data-group-id="3861189639-3">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="6261364803-5">(</span><span class="p" data-group-id="6261364803-5">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="3861189639-5">(</span><span class="p" data-group-id="3861189639-5">)</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6261364803-6">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6261364803-7">[</span><span class="p" data-group-id="6261364803-7">]</span><span class="p" data-group-id="6261364803-6">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3861189639-6">(</span><span class="s">&quot;Pong timed out</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3861189639-7">[</span><span class="p" data-group-id="3861189639-7">]</span><span class="p" data-group-id="3861189639-6">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The time-out (<code class="inline">after 5000</code>) is started when <code class="inline">receive</code> is entered. The time-out
│ │ │  is canceled if <code class="inline">{ping,Ping_PID}</code> is received. If <code class="inline">{ping,Ping_PID}</code> is not
│ │ │  received, the actions following the time-out are done after 5000 milliseconds.
│ │ │  <code class="inline">after</code> must be last in the <code class="inline">receive</code>, that is, preceded by all other message
│ │ │  reception specifications in the <code class="inline">receive</code>. It is also possible to call a
│ │ │ -function that returned an integer for the time-out:</p><pre><code class="makeup erlang" translate="no"><span class="k">after</span><span class="w"> </span><span class="nf">pong_timeout</span><span class="p" data-group-id="4603250630-1">(</span><span class="p" data-group-id="4603250630-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>In general, there are better ways than using time-outs to supervise parts of a
│ │ │ +function that returned an integer for the time-out:</p><pre><code class="makeup erlang" translate="no"><span class="k">after</span><span class="w"> </span><span class="nf">pong_timeout</span><span class="p" data-group-id="9447670719-1">(</span><span class="p" data-group-id="9447670719-1">)</span><span class="w"> </span><span class="p">-&gt;</span></code></pre><p>In general, there are better ways than using time-outs to supervise parts of a
│ │ │  distributed Erlang system. Time-outs are usually appropriate to supervise
│ │ │  external events, for example, if you have expected a message from some external
│ │ │  system within a specified time. For example, a time-out can be used to log a
│ │ │  user out of the messenger system if they have not accessed it for, say, ten
│ │ │  minutes.</p><h2 id="error-handling" class="section-heading">
│ │ │    <a href="#error-handling" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -209,96 +209,96 @@
│ │ │  something called a <em>signal</em> to all the processes it has links to.</p><p>The signal carries information about the pid it was sent from and the exit
│ │ │  reason.</p><p>The default behaviour of a process that receives a normal exit is to ignore the
│ │ │  signal.</p><p>The default behaviour in the two other cases (that is, abnormal exit) above is
│ │ │  to:</p><ul><li>Bypass all messages to the receiving process.</li><li>Kill the receiving process.</li><li>Propagate the same error signal to the links of the killed process.</li></ul><p>In this way you can connect all processes in a transaction together using links.
│ │ │  If one of the processes exits abnormally, all the processes in the transaction
│ │ │  are killed. As it is often wanted to create a process and link to it at the same
│ │ │  time, there is a special BIF, <a href="../../erts-15.2.7.3/doc/html/erlang.html#spawn_link/1">spawn_link</a> that does the
│ │ │ -same as <code class="inline">spawn</code>, but also creates a link to the spawned process.</p><p>Now an example of the ping pong example using links to terminate &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6494732251-1">(</span><span class="ss">tut20</span><span class="p" data-group-id="6494732251-1">)</span><span class="p">.</span><span class="w">
│ │ │ +same as <code class="inline">spawn</code>, but also creates a link to the spawned process.</p><p>Now an example of the ping pong example using links to terminate &quot;pong&quot;:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2870872003-1">(</span><span class="ss">tut20</span><span class="p" data-group-id="2870872003-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6494732251-2">(</span><span class="p" data-group-id="6494732251-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6494732251-3">]</span><span class="p" data-group-id="6494732251-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2870872003-2">(</span><span class="p" data-group-id="2870872003-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2870872003-3">]</span><span class="p" data-group-id="2870872003-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="6494732251-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="6494732251-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">link</span><span class="p" data-group-id="6494732251-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="6494732251-5">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="6494732251-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="6494732251-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="2870872003-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2870872003-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">link</span><span class="p" data-group-id="2870872003-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="2870872003-5">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="2870872003-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2870872003-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="6494732251-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6494732251-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="6494732251-8">(</span><span class="ss">ping</span><span class="p" data-group-id="6494732251-8">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="2870872003-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="2870872003-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="2870872003-8">(</span><span class="ss">ping</span><span class="p" data-group-id="2870872003-8">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="6494732251-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="6494732251-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6494732251-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6494732251-11">(</span><span class="p" data-group-id="6494732251-11">)</span><span class="p" data-group-id="6494732251-10">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="2870872003-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2870872003-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2870872003-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="2870872003-11">(</span><span class="p" data-group-id="2870872003-11">)</span><span class="p" data-group-id="2870872003-10">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6494732251-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6494732251-13">[</span><span class="p" data-group-id="6494732251-13">]</span><span class="p" data-group-id="6494732251-12">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2870872003-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2870872003-13">[</span><span class="p" data-group-id="2870872003-13">]</span><span class="p" data-group-id="2870872003-12">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="6494732251-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="6494732251-14">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="2870872003-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="2870872003-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="6494732251-15">(</span><span class="p" data-group-id="6494732251-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="2870872003-15">(</span><span class="p" data-group-id="2870872003-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="6494732251-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="6494732251-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6494732251-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6494732251-18">[</span><span class="p" data-group-id="6494732251-18">]</span><span class="p" data-group-id="6494732251-17">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2870872003-16">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="2870872003-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2870872003-17">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2870872003-18">[</span><span class="p" data-group-id="2870872003-18">]</span><span class="p" data-group-id="2870872003-17">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong</span><span class="p" data-group-id="6494732251-19">(</span><span class="p" data-group-id="6494732251-19">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong</span><span class="p" data-group-id="2870872003-19">(</span><span class="p" data-group-id="2870872003-19">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="6494732251-20">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="6494732251-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="6494732251-21">(</span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6494732251-22">[</span><span class="p" data-group-id="6494732251-22">]</span><span class="p" data-group-id="6494732251-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="6494732251-23">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6494732251-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="6494732251-24">]</span><span class="p" data-group-id="6494732251-23">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)3&gt; tut20:start(s2@kosken).
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="2870872003-20">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="2870872003-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="2870872003-21">(</span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2870872003-22">[</span><span class="p" data-group-id="2870872003-22">]</span><span class="p" data-group-id="2870872003-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="2870872003-23">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut20</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2870872003-24">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="2870872003-24">]</span><span class="p" data-group-id="2870872003-23">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)3&gt; tut20:start(s2@kosken).
│ │ │  Pong received ping
│ │ │  &lt;3820.41.0&gt;
│ │ │  Ping received pong
│ │ │  Pong received ping
│ │ │  Ping received pong
│ │ │  Pong received ping
│ │ │  Ping received pong</code></pre><p>This is a slight modification of the ping pong program where both processes are
│ │ │  spawned from the same <code class="inline">start/1</code> function, and the &quot;ping&quot; process can be spawned
│ │ │  on a separate node. Notice the use of the <code class="inline">link</code> BIF. &quot;Ping&quot; calls
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#exit/1"><code class="inline">exit(ping)</code></a> when it finishes and this causes an exit signal to be
│ │ │  sent to &quot;pong&quot;, which also terminates.</p><p>It is possible to modify the default behaviour of a process so that it does not
│ │ │  get killed when it receives abnormal exit signals. Instead, all signals are
│ │ │  turned into normal messages on the format <code class="inline">{'EXIT',FromPID,Reason}</code> and added to
│ │ │ -the end of the receiving process' message queue. This behaviour is set by:</p><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="3972307587-1">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3972307587-1">)</span></code></pre><p>There are several other process flags, see <a href="../../erts-15.2.7.3/doc/html/erlang.html#process_flag/2">erlang(3)</a>.
│ │ │ +the end of the receiving process' message queue. This behaviour is set by:</p><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="4629569204-1">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="4629569204-1">)</span></code></pre><p>There are several other process flags, see <a href="../../erts-15.2.7.3/doc/html/erlang.html#process_flag/2">erlang(3)</a>.
│ │ │  Changing the default behaviour of a process in this way is usually not done in
│ │ │  standard user programs, but is left to the supervisory programs in OTP. However,
│ │ │ -the ping pong program is modified to illustrate exit trapping.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7270888386-1">(</span><span class="ss">tut21</span><span class="p" data-group-id="7270888386-1">)</span><span class="p">.</span><span class="w">
│ │ │ +the ping pong program is modified to illustrate exit trapping.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8405019610-1">(</span><span class="ss">tut21</span><span class="p" data-group-id="8405019610-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7270888386-2">(</span><span class="p" data-group-id="7270888386-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7270888386-3">]</span><span class="p" data-group-id="7270888386-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8405019610-2">(</span><span class="p" data-group-id="8405019610-3">[</span><span class="ss">start</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w">  </span><span class="ss">ping</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8405019610-3">]</span><span class="p" data-group-id="8405019610-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping</span><span class="p" data-group-id="7270888386-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="7270888386-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">link</span><span class="p" data-group-id="7270888386-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="7270888386-5">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="7270888386-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="7270888386-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">ping</span><span class="p" data-group-id="8405019610-4">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="8405019610-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">link</span><span class="p" data-group-id="8405019610-5">(</span><span class="n">Pong_Pid</span><span class="p" data-group-id="8405019610-5">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="8405019610-6">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="8405019610-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="7270888386-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7270888386-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="7270888386-8">(</span><span class="ss">ping</span><span class="p" data-group-id="7270888386-8">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="8405019610-7">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="8405019610-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="8405019610-8">(</span><span class="ss">ping</span><span class="p" data-group-id="8405019610-8">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">ping1</span><span class="p" data-group-id="7270888386-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="7270888386-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7270888386-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7270888386-11">(</span><span class="p" data-group-id="7270888386-11">)</span><span class="p" data-group-id="7270888386-10">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">ping1</span><span class="p" data-group-id="8405019610-9">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="8405019610-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Pong_Pid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8405019610-10">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8405019610-11">(</span><span class="p" data-group-id="8405019610-11">)</span><span class="p" data-group-id="8405019610-10">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">pong</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7270888386-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7270888386-13">[</span><span class="p" data-group-id="7270888386-13">]</span><span class="p" data-group-id="7270888386-12">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8405019610-12">(</span><span class="s">&quot;Ping received pong</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8405019610-13">[</span><span class="p" data-group-id="8405019610-13">]</span><span class="p" data-group-id="8405019610-12">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">ping1</span><span class="p" data-group-id="7270888386-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="7270888386-14">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">ping1</span><span class="p" data-group-id="8405019610-14">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">Pong_Pid</span><span class="p" data-group-id="8405019610-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong</span><span class="p" data-group-id="7270888386-15">(</span><span class="p" data-group-id="7270888386-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="7270888386-16">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="7270888386-16">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">pong1</span><span class="p" data-group-id="7270888386-17">(</span><span class="p" data-group-id="7270888386-17">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">pong</span><span class="p" data-group-id="8405019610-15">(</span><span class="p" data-group-id="8405019610-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="8405019610-16">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8405019610-16">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">pong1</span><span class="p" data-group-id="8405019610-17">(</span><span class="p" data-group-id="8405019610-17">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">pong1</span><span class="p" data-group-id="7270888386-18">(</span><span class="p" data-group-id="7270888386-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">pong1</span><span class="p" data-group-id="8405019610-18">(</span><span class="p" data-group-id="8405019610-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7270888386-19">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="7270888386-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7270888386-20">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7270888386-21">[</span><span class="p" data-group-id="7270888386-21">]</span><span class="p" data-group-id="7270888386-20">)</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8405019610-19">{</span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="n">Ping_PID</span><span class="p" data-group-id="8405019610-19">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8405019610-20">(</span><span class="s">&quot;Pong received ping</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8405019610-21">[</span><span class="p" data-group-id="8405019610-21">]</span><span class="p" data-group-id="8405019610-20">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">Ping_PID</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">pong1</span><span class="p" data-group-id="7270888386-22">(</span><span class="p" data-group-id="7270888386-22">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7270888386-23">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="7270888386-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7270888386-24">(</span><span class="s">&quot;pong exiting, got </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7270888386-25">[</span><span class="p" data-group-id="7270888386-26">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="7270888386-26">}</span><span class="p" data-group-id="7270888386-25">]</span><span class="p" data-group-id="7270888386-24">)</span><span class="w">
│ │ │ +            </span><span class="nf">pong1</span><span class="p" data-group-id="8405019610-22">(</span><span class="p" data-group-id="8405019610-22">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8405019610-23">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="8405019610-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8405019610-24">(</span><span class="s">&quot;pong exiting, got </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8405019610-25">[</span><span class="p" data-group-id="8405019610-26">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="8405019610-26">}</span><span class="p" data-group-id="8405019610-25">]</span><span class="p" data-group-id="8405019610-24">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start</span><span class="p" data-group-id="7270888386-27">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="7270888386-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="7270888386-28">(</span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7270888386-29">[</span><span class="p" data-group-id="7270888386-29">]</span><span class="p" data-group-id="7270888386-28">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="7270888386-30">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7270888386-31">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="7270888386-31">]</span><span class="p" data-group-id="7270888386-30">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)1&gt; tut21:start(s2@gollum).
│ │ │ +</span><span class="nf">start</span><span class="p" data-group-id="8405019610-27">(</span><span class="n">Ping_Node</span><span class="p" data-group-id="8405019610-27">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">PongPID</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="8405019610-28">(</span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">pong</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8405019610-29">[</span><span class="p" data-group-id="8405019610-29">]</span><span class="p" data-group-id="8405019610-28">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="8405019610-30">(</span><span class="n">Ping_Node</span><span class="p">,</span><span class="w"> </span><span class="ss">tut21</span><span class="p">,</span><span class="w"> </span><span class="ss">ping</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8405019610-31">[</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="n">PongPID</span><span class="p" data-group-id="8405019610-31">]</span><span class="p" data-group-id="8405019610-30">)</span><span class="p">.</span></code></pre><pre><code class="text">(s1@bill)1&gt; tut21:start(s2@gollum).
│ │ │  &lt;3820.39.0&gt;
│ │ │  Pong received ping
│ │ │  Ping received pong
│ │ │  Pong received ping
│ │ │  Ping received pong
│ │ │  Pong received ping
│ │ │  Ping received pong
│ │ │ @@ -351,135 +351,135 @@
│ │ │  </span><span class="c1">%%% Started: messenger:client(Server_Node, Name)</span><span class="w">
│ │ │  </span><span class="c1">%%% To client: logoff</span><span class="w">
│ │ │  </span><span class="c1">%%% To client: {message_to, ToName, Message}</span><span class="w">
│ │ │  </span><span class="c1">%%%</span><span class="w">
│ │ │  </span><span class="c1">%%% Configuration: change the server_node() function to return the</span><span class="w">
│ │ │  </span><span class="c1">%%% name of the node where the messenger server runs</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8407209437-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="8407209437-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8407209437-2">(</span><span class="p" data-group-id="8407209437-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8407209437-3">]</span><span class="p" data-group-id="8407209437-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0697192316-1">(</span><span class="ss">messenger</span><span class="p" data-group-id="0697192316-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0697192316-2">(</span><span class="p" data-group-id="0697192316-3">[</span><span class="ss">start_server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="ss">logon</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">logoff</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">message</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="0697192316-3">]</span><span class="p" data-group-id="0697192316-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Change the function below to return the name of the node where the</span><span class="w">
│ │ │  </span><span class="c1">%%% messenger server runs</span><span class="w">
│ │ │ -</span><span class="nf">server_node</span><span class="p" data-group-id="8407209437-4">(</span><span class="p" data-group-id="8407209437-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_node</span><span class="p" data-group-id="0697192316-4">(</span><span class="p" data-group-id="0697192316-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">messenger@super</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% This is the server process for the &quot;messenger&quot;</span><span class="w">
│ │ │  </span><span class="c1">%%% the user list has the format [{ClientPid1, Name1},{ClientPid22, Name2},...]</span><span class="w">
│ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="8407209437-5">(</span><span class="p" data-group-id="8407209437-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="8407209437-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8407209437-6">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">server</span><span class="p" data-group-id="8407209437-7">(</span><span class="p" data-group-id="8407209437-8">[</span><span class="p" data-group-id="8407209437-8">]</span><span class="p" data-group-id="8407209437-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="0697192316-5">(</span><span class="p" data-group-id="0697192316-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="0697192316-6">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="0697192316-6">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">server</span><span class="p" data-group-id="0697192316-7">(</span><span class="p" data-group-id="0697192316-8">[</span><span class="p" data-group-id="0697192316-8">]</span><span class="p" data-group-id="0697192316-7">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">server</span><span class="p" data-group-id="8407209437-9">(</span><span class="n">User_List</span><span class="p" data-group-id="8407209437-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server</span><span class="p" data-group-id="0697192316-9">(</span><span class="n">User_List</span><span class="p" data-group-id="0697192316-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-10">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8407209437-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="8407209437-11">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-11">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="8407209437-12">(</span><span class="n">New_User_List</span><span class="p" data-group-id="8407209437-12">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-13">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="8407209437-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="8407209437-14">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-14">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="8407209437-15">(</span><span class="n">New_User_List</span><span class="p" data-group-id="8407209437-15">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-16">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="8407209437-17">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-17">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8407209437-18">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-19">[</span><span class="n">User_List</span><span class="p" data-group-id="8407209437-19">]</span><span class="p" data-group-id="8407209437-18">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">server</span><span class="p" data-group-id="8407209437-20">(</span><span class="n">User_List</span><span class="p" data-group-id="8407209437-20">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-10">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0697192316-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logon</span><span class="p" data-group-id="0697192316-11">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-11">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="0697192316-12">(</span><span class="n">New_User_List</span><span class="p" data-group-id="0697192316-12">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-13">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="0697192316-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">New_User_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">server_logoff</span><span class="p" data-group-id="0697192316-14">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-14">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="0697192316-15">(</span><span class="n">New_User_List</span><span class="p" data-group-id="0697192316-15">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-16">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-16">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="0697192316-17">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-17">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0697192316-18">(</span><span class="s">&quot;list is now: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-19">[</span><span class="n">User_List</span><span class="p" data-group-id="0697192316-19">]</span><span class="p" data-group-id="0697192316-18">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">server</span><span class="p" data-group-id="0697192316-20">(</span><span class="n">User_List</span><span class="p" data-group-id="0697192316-20">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Start the server</span><span class="w">
│ │ │ -</span><span class="nf">start_server</span><span class="p" data-group-id="8407209437-21">(</span><span class="p" data-group-id="8407209437-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="8407209437-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="8407209437-23">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-24">[</span><span class="p" data-group-id="8407209437-24">]</span><span class="p" data-group-id="8407209437-23">)</span><span class="p" data-group-id="8407209437-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_server</span><span class="p" data-group-id="0697192316-21">(</span><span class="p" data-group-id="0697192316-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="0697192316-22">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="0697192316-23">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">server</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-24">[</span><span class="p" data-group-id="0697192316-24">]</span><span class="p" data-group-id="0697192316-23">)</span><span class="p" data-group-id="0697192316-22">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Server adds a new user to the user list</span><span class="w">
│ │ │ -</span><span class="nf">server_logon</span><span class="p" data-group-id="8407209437-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_logon</span><span class="p" data-group-id="0697192316-25">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% check if logged on anywhere else</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="8407209437-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keymember</span><span class="p" data-group-id="0697192316-26">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-26">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-27">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="8407209437-27">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-27">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">user_exists_at_other_node</span><span class="p" data-group-id="0697192316-27">}</span><span class="p">,</span><span class="w">  </span><span class="c1">%reject logon</span><span class="w">
│ │ │              </span><span class="n">User_List</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-28">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="8407209437-28">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">link</span><span class="p" data-group-id="8407209437-29">(</span><span class="n">From</span><span class="p" data-group-id="8407209437-29">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="8407209437-30">[</span><span class="p" data-group-id="8407209437-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8407209437-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-28">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">logged_on</span><span class="p" data-group-id="0697192316-28">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">link</span><span class="p" data-group-id="0697192316-29">(</span><span class="n">From</span><span class="p" data-group-id="0697192316-29">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="0697192316-30">[</span><span class="p" data-group-id="0697192316-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0697192316-31">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-30">]</span><span class="w">        </span><span class="c1">%add user to the list</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Server deletes a user from the user list</span><span class="w">
│ │ │ -</span><span class="nf">server_logoff</span><span class="p" data-group-id="8407209437-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="8407209437-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-33">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">server_logoff</span><span class="p" data-group-id="0697192316-32">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keydelete</span><span class="p" data-group-id="0697192316-33">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-33">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  
│ │ │  </span><span class="c1">%%% Server transfers a message between user</span><span class="w">
│ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="8407209437-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="0697192316-34">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-34">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% check that the user is logged on and who he is</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8407209437-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="0697192316-35">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-35">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-36">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="8407209437-36">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8407209437-38">}</span><span class="p" data-group-id="8407209437-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">server_transfer</span><span class="p" data-group-id="8407209437-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-39">)</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-36">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="ss">you_are_not_logged_on</span><span class="p" data-group-id="0697192316-36">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-37">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-38">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0697192316-38">}</span><span class="p" data-group-id="0697192316-37">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">server_transfer</span><span class="p" data-group-id="0697192316-39">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-39">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% If the user exists, send the message</span><span class="w">
│ │ │ -</span><span class="nf">server_transfer</span><span class="p" data-group-id="8407209437-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">server_transfer</span><span class="p" data-group-id="0697192316-40">(</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-40">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Find the receiver and send the message</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="8407209437-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="8407209437-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">keysearch</span><span class="p" data-group-id="0697192316-41">(</span><span class="n">To</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">User_List</span><span class="p" data-group-id="0697192316-41">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">false</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="8407209437-42">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="8407209437-44">}</span><span class="p" data-group-id="8407209437-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-45">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-45">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-46">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="8407209437-46">}</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-42">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">receiver_not_found</span><span class="p" data-group-id="0697192316-42">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-43">{</span><span class="ss">value</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-44">{</span><span class="n">ToPid</span><span class="p">,</span><span class="w"> </span><span class="n">To</span><span class="p" data-group-id="0697192316-44">}</span><span class="p" data-group-id="0697192316-43">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">ToPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-45">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-45">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-46">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">sent</span><span class="p" data-group-id="0697192316-46">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% User Commands</span><span class="w">
│ │ │ -</span><span class="nf">logon</span><span class="p" data-group-id="8407209437-47">(</span><span class="n">Name</span><span class="p" data-group-id="8407209437-47">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8407209437-48">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8407209437-48">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">logon</span><span class="p" data-group-id="0697192316-47">(</span><span class="n">Name</span><span class="p" data-group-id="0697192316-47">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="0697192316-48">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0697192316-48">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">register</span><span class="p" data-group-id="8407209437-49">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ -                     </span><span class="nf">spawn</span><span class="p" data-group-id="8407209437-50">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-51">[</span><span class="nf">server_node</span><span class="p" data-group-id="8407209437-52">(</span><span class="p" data-group-id="8407209437-52">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8407209437-51">]</span><span class="p" data-group-id="8407209437-50">)</span><span class="p" data-group-id="8407209437-49">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="nf">register</span><span class="p" data-group-id="0697192316-49">(</span><span class="ss">mess_client</span><span class="p">,</span><span class="w">
│ │ │ +                     </span><span class="nf">spawn</span><span class="p" data-group-id="0697192316-50">(</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">client</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-51">[</span><span class="nf">server_node</span><span class="p" data-group-id="0697192316-52">(</span><span class="p" data-group-id="0697192316-52">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0697192316-51">]</span><span class="p" data-group-id="0697192316-50">)</span><span class="p" data-group-id="0697192316-49">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">already_logged_on</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">logoff</span><span class="p" data-group-id="8407209437-53">(</span><span class="p" data-group-id="8407209437-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">logoff</span><span class="p" data-group-id="0697192316-53">(</span><span class="p" data-group-id="0697192316-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="ss">logoff</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">message</span><span class="p" data-group-id="8407209437-54">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-54">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="8407209437-55">(</span><span class="ss">mess_client</span><span class="p" data-group-id="8407209437-55">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │ +</span><span class="nf">message</span><span class="p" data-group-id="0697192316-54">(</span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-54">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="0697192316-55">(</span><span class="ss">mess_client</span><span class="p" data-group-id="0697192316-55">)</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="c1">% Test if the client is running</span><span class="w">
│ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">not_logged_on</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-56">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-56">}</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">mess_client</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-56">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-56">}</span><span class="p">,</span><span class="w">
│ │ │               </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% The client process which runs on each user node</span><span class="w">
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="8407209437-57">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8407209437-57">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8407209437-58">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="8407209437-58">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-59">{</span><span class="nf">self</span><span class="p" data-group-id="8407209437-60">(</span><span class="p" data-group-id="8407209437-60">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8407209437-59">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">await_result</span><span class="p" data-group-id="8407209437-61">(</span><span class="p" data-group-id="8407209437-61">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="8407209437-62">(</span><span class="n">Server_Node</span><span class="p" data-group-id="8407209437-62">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="0697192316-57">(</span><span class="n">Server_Node</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0697192316-57">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0697192316-58">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0697192316-58">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-59">{</span><span class="nf">self</span><span class="p" data-group-id="0697192316-60">(</span><span class="p" data-group-id="0697192316-60">)</span><span class="p">,</span><span class="w"> </span><span class="ss">logon</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="0697192316-59">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">await_result</span><span class="p" data-group-id="0697192316-61">(</span><span class="p" data-group-id="0697192316-61">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="0697192316-62">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0697192316-62">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="8407209437-63">(</span><span class="n">Server_Node</span><span class="p" data-group-id="8407209437-63">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="0697192316-63">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0697192316-63">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="ss">logoff</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="8407209437-64">(</span><span class="ss">normal</span><span class="p" data-group-id="8407209437-64">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-65">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-65">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="8407209437-66">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="8407209437-66">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8407209437-67">{</span><span class="nf">self</span><span class="p" data-group-id="8407209437-68">(</span><span class="p" data-group-id="8407209437-68">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-67">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">await_result</span><span class="p" data-group-id="8407209437-69">(</span><span class="p" data-group-id="8407209437-69">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-70">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-70">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8407209437-71">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-72">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="8407209437-72">]</span><span class="p" data-group-id="8407209437-71">)</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0697192316-64">(</span><span class="ss">normal</span><span class="p" data-group-id="0697192316-64">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-65">{</span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-65">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="0697192316-66">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">Server_Node</span><span class="p" data-group-id="0697192316-66">}</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0697192316-67">{</span><span class="nf">self</span><span class="p" data-group-id="0697192316-68">(</span><span class="p" data-group-id="0697192316-68">)</span><span class="p">,</span><span class="w"> </span><span class="ss">message_to</span><span class="p">,</span><span class="w"> </span><span class="n">ToName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-67">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">await_result</span><span class="p" data-group-id="0697192316-69">(</span><span class="p" data-group-id="0697192316-69">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-70">{</span><span class="ss">message_from</span><span class="p">,</span><span class="w"> </span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-70">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0697192316-71">(</span><span class="s">&quot;Message from </span><span class="si">~p</span><span class="s">: </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-72">[</span><span class="n">FromName</span><span class="p">,</span><span class="w"> </span><span class="n">Message</span><span class="p" data-group-id="0697192316-72">]</span><span class="p" data-group-id="0697192316-71">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">client</span><span class="p" data-group-id="8407209437-73">(</span><span class="n">Server_Node</span><span class="p" data-group-id="8407209437-73">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">client</span><span class="p" data-group-id="0697192316-73">(</span><span class="n">Server_Node</span><span class="p" data-group-id="0697192316-73">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% wait for a response from the server</span><span class="w">
│ │ │ -</span><span class="nf">await_result</span><span class="p" data-group-id="8407209437-74">(</span><span class="p" data-group-id="8407209437-74">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">await_result</span><span class="p" data-group-id="0697192316-74">(</span><span class="p" data-group-id="0697192316-74">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-75">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="8407209437-75">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8407209437-76">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-77">[</span><span class="n">Why</span><span class="p" data-group-id="8407209437-77">]</span><span class="p" data-group-id="8407209437-76">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="8407209437-78">(</span><span class="ss">normal</span><span class="p" data-group-id="8407209437-78">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8407209437-79">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="8407209437-79">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8407209437-80">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-81">[</span><span class="n">What</span><span class="p" data-group-id="8407209437-81">]</span><span class="p" data-group-id="8407209437-80">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-75">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="ss">stop</span><span class="p">,</span><span class="w"> </span><span class="n">Why</span><span class="p" data-group-id="0697192316-75">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Stop the client</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0697192316-76">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-77">[</span><span class="n">Why</span><span class="p" data-group-id="0697192316-77">]</span><span class="p" data-group-id="0697192316-76">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0697192316-78">(</span><span class="ss">normal</span><span class="p" data-group-id="0697192316-78">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0697192316-79">{</span><span class="ss">messenger</span><span class="p">,</span><span class="w"> </span><span class="n">What</span><span class="p" data-group-id="0697192316-79">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Normal response</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0697192316-80">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-81">[</span><span class="n">What</span><span class="p" data-group-id="0697192316-81">]</span><span class="p" data-group-id="0697192316-80">)</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8407209437-82">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8407209437-83">[</span><span class="p" data-group-id="8407209437-83">]</span><span class="p" data-group-id="8407209437-82">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="8407209437-84">(</span><span class="ss">timeout</span><span class="p" data-group-id="8407209437-84">)</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0697192316-82">(</span><span class="s">&quot;No response from server</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0697192316-83">[</span><span class="p" data-group-id="0697192316-83">]</span><span class="p" data-group-id="0697192316-82">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="0697192316-84">(</span><span class="ss">timeout</span><span class="p" data-group-id="0697192316-84">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The following changes are added:</p><p>The messenger server traps exits. If it receives an exit signal,
│ │ │  <code class="inline">{'EXIT',From,Reason}</code>, this means that a client process has terminated or is
│ │ │  unreachable for one of the following reasons:</p><ul><li>The user has logged off (the &quot;logoff&quot; message is removed).</li><li>The network connection to the client is broken.</li><li>The node on which the client process resides has gone down.</li><li>The client processes has done some illegal operation.</li></ul><p>If an exit signal is received as above, the tuple <code class="inline">{From,Name}</code> is deleted from
│ │ │  the servers <code class="inline">User_List</code> using the <code class="inline">server_logoff</code> function. If the node on which
│ │ │  the server runs goes down, an exit signal (automatically generated by the
│ │ │  system) is sent to all of the client processes:
│ │ │  <code class="inline">{'EXIT',MessengerPID,noconnection}</code> causing all the client processes to
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/seq_prog.html
│ │ │ @@ -136,293 +136,293 @@
│ │ │  </span><span class="mi">7</span><span class="gp unselectable">
│ │ │  2&gt; </span></code></pre><p>As shown, the Erlang shell numbers the lines that can be entered, (as 1&gt; 2&gt;) and
│ │ │  that it correctly says that 2 + 5 is 7. If you make writing mistakes in the
│ │ │  shell, you can delete with the backspace key, as in most shells. There are many
│ │ │  more editing commands in the shell (see
│ │ │  <a href="../../erts-15.2.7.3/doc/html/tty.html">tty - A command line interface</a> in ERTS User's Guide).</p><p>(Notice that many line numbers given by the shell in the following examples are
│ │ │  out of sequence. This is because this tutorial was written and code-tested in
│ │ │ -separate sessions).</p><p>Here is a bit more complex calculation:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="4716806172-1">(</span><span class="mi">42</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">77</span><span class="p" data-group-id="4716806172-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">66</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │ +separate sessions).</p><p>Here is a bit more complex calculation:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">2&gt; </span><span class="p" data-group-id="7823365189-1">(</span><span class="mi">42</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">77</span><span class="p" data-group-id="7823365189-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">66</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">3</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">2618.0</span></code></pre><p>Notice the use of brackets, the multiplication operator <code class="inline">*</code>, and the division
│ │ │  operator <code class="inline">/</code>, as in normal arithmetic (see
│ │ │  <a href="../../doc/system/expressions.html">Expressions</a>).</p><p>Press Control-C to shut down the Erlang system and the Erlang shell.</p><p>The following output is shown:</p><pre><code class="text">BREAK: (a)bort (c)ontinue (p)roc info (i)nfo (l)oaded
│ │ │         (v)ersion (k)ill (D)b-tables (d)istribution
│ │ │  a
│ │ │ -$</code></pre><p>Type <code class="inline">a</code> to leave the Erlang system.</p><p>Another way to shut down the Erlang system is by entering <a href="../../erts-15.2.7.3/doc/html/erlang.html#halt/0"><code class="inline">halt/0</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">halt</span><span class="p" data-group-id="4302512415-1">(</span><span class="p" data-group-id="4302512415-1">)</span><span class="p">.</span><span class="w">
│ │ │ +$</code></pre><p>Type <code class="inline">a</code> to leave the Erlang system.</p><p>Another way to shut down the Erlang system is by entering <a href="../../erts-15.2.7.3/doc/html/erlang.html#halt/0"><code class="inline">halt/0</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">halt</span><span class="p" data-group-id="6202697675-1">(</span><span class="p" data-group-id="6202697675-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="err">$</span></code></pre><h2 id="modules-and-functions" class="section-heading">
│ │ │    <a href="#modules-and-functions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Modules and Functions</span>
│ │ │  </h2>
│ │ │  <p>A programming language is not much use if you only can run code from the shell.
│ │ │  So here is a small Erlang program. Enter it into a file named <code class="inline">tut.erl</code> using a
│ │ │  suitable text editor. The file name <code class="inline">tut.erl</code> is important, and also that it is
│ │ │  in the same directory as the one where you started <code class="inline">erl</code>). If you are lucky your
│ │ │  editor has an Erlang mode that makes it easier for you to enter and format your
│ │ │  code nicely (see <a href="../../lib/tools-4.1.1/doc/html/erlang_mode_chapter.html">The Erlang mode for Emacs</a>
│ │ │  in Tools User's Guide), but you can manage perfectly well without. Here is the
│ │ │ -code to enter:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7006812441-1">(</span><span class="ss">tut</span><span class="p" data-group-id="7006812441-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7006812441-2">(</span><span class="p" data-group-id="7006812441-3">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7006812441-3">]</span><span class="p" data-group-id="7006812441-2">)</span><span class="p">.</span><span class="w">
│ │ │ +code to enter:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1342470412-1">(</span><span class="ss">tut</span><span class="p" data-group-id="1342470412-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1342470412-2">(</span><span class="p" data-group-id="1342470412-3">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1342470412-3">]</span><span class="p" data-group-id="1342470412-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">double</span><span class="p" data-group-id="7006812441-4">(</span><span class="n">X</span><span class="p" data-group-id="7006812441-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">double</span><span class="p" data-group-id="1342470412-4">(</span><span class="n">X</span><span class="p" data-group-id="1342470412-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="mi">2</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">X</span><span class="p">.</span></code></pre><p>It is not hard to guess that this program doubles the value of numbers. The
│ │ │  first two lines of the code are described later. Let us compile the program.
│ │ │ -This can be done in an Erlang shell as follows, where <code class="inline">c</code> means compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">c</span><span class="p" data-group-id="5618107835-1">(</span><span class="ss">tut</span><span class="p" data-group-id="5618107835-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5618107835-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut</span><span class="p" data-group-id="5618107835-2">}</span></code></pre><p>The <code class="inline">{ok,tut}</code> means that the compilation is OK. If it says <code class="inline">error</code> it means
│ │ │ +This can be done in an Erlang shell as follows, where <code class="inline">c</code> means compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">3&gt; </span><span class="nf">c</span><span class="p" data-group-id="8335242160-1">(</span><span class="ss">tut</span><span class="p" data-group-id="8335242160-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8335242160-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut</span><span class="p" data-group-id="8335242160-2">}</span></code></pre><p>The <code class="inline">{ok,tut}</code> means that the compilation is OK. If it says <code class="inline">error</code> it means
│ │ │  that there is some mistake in the text that you entered. Additional error
│ │ │  messages gives an idea to what is wrong so you can modify the text and then try
│ │ │ -to compile the program again.</p><p>Now run the program:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="9908969500-1">(</span><span class="mi">10</span><span class="p" data-group-id="9908969500-1">)</span><span class="p">.</span><span class="w">
│ │ │ +to compile the program again.</p><p>Now run the program:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="2930102939-1">(</span><span class="mi">10</span><span class="p" data-group-id="2930102939-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">20</span></code></pre><p>As expected, double of 10 is 20.</p><p>Now let us get back to the first two lines of the code. Erlang programs are
│ │ │  written in files. Each file contains an Erlang <em>module</em>. The first line of code
│ │ │ -in the module is the module name (see <a href="../../doc/system/modules.html">Modules</a>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3185110890-1">(</span><span class="ss">tut</span><span class="p" data-group-id="3185110890-1">)</span><span class="p">.</span></code></pre><p>Thus, the module is called <em>tut</em>. Notice the full stop <code class="inline">.</code> at the end of the
│ │ │ +in the module is the module name (see <a href="../../doc/system/modules.html">Modules</a>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9666700841-1">(</span><span class="ss">tut</span><span class="p" data-group-id="9666700841-1">)</span><span class="p">.</span></code></pre><p>Thus, the module is called <em>tut</em>. Notice the full stop <code class="inline">.</code> at the end of the
│ │ │  line. The files which are used to store the module must have the same name as
│ │ │  the module but with the extension <code class="inline">.erl</code>. In this case the file name is
│ │ │  <code class="inline">tut.erl</code>. When using a function in another module, the syntax
│ │ │  <code class="inline">module_name:function_name(arguments)</code> is used. So the following means call
│ │ │ -function <code class="inline">double</code> in module <code class="inline">tut</code> with argument <code class="inline">10</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="2895905421-1">(</span><span class="mi">10</span><span class="p" data-group-id="2895905421-1">)</span><span class="p">.</span></code></pre><p>The second line says that the module <code class="inline">tut</code> contains a function called <code class="inline">double</code>,
│ │ │ -which takes one argument (<code class="inline">X</code> in our example):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4990427314-1">(</span><span class="p" data-group-id="4990427314-2">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4990427314-2">]</span><span class="p" data-group-id="4990427314-1">)</span><span class="p">.</span></code></pre><p>The second line also says that this function can be called from outside the
│ │ │ +function <code class="inline">double</code> in module <code class="inline">tut</code> with argument <code class="inline">10</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">4&gt; </span><span class="nc">tut</span><span class="p">:</span><span class="nf">double</span><span class="p" data-group-id="5129095679-1">(</span><span class="mi">10</span><span class="p" data-group-id="5129095679-1">)</span><span class="p">.</span></code></pre><p>The second line says that the module <code class="inline">tut</code> contains a function called <code class="inline">double</code>,
│ │ │ +which takes one argument (<code class="inline">X</code> in our example):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5965468233-1">(</span><span class="p" data-group-id="5965468233-2">[</span><span class="ss">double</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5965468233-2">]</span><span class="p" data-group-id="5965468233-1">)</span><span class="p">.</span></code></pre><p>The second line also says that this function can be called from outside the
│ │ │  module <code class="inline">tut</code>. More about this later. Again, notice the <code class="inline">.</code> at the end of the
│ │ │  line.</p><p>Now for a more complicated example, the factorial of a number. For example, the
│ │ │ -factorial of 4 is 4 <em> 3 </em> 2 * 1, which equals 24.</p><p>Enter the following code in a file named <code class="inline">tut1.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0193224384-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="0193224384-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0193224384-2">(</span><span class="p" data-group-id="0193224384-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0193224384-3">]</span><span class="p" data-group-id="0193224384-2">)</span><span class="p">.</span><span class="w">
│ │ │ +factorial of 4 is 4 <em> 3 </em> 2 * 1, which equals 24.</p><p>Enter the following code in a file named <code class="inline">tut1.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7704681582-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="7704681582-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7704681582-2">(</span><span class="p" data-group-id="7704681582-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7704681582-3">]</span><span class="p" data-group-id="7704681582-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="0193224384-4">(</span><span class="mi">1</span><span class="p" data-group-id="0193224384-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="7704681582-4">(</span><span class="mi">1</span><span class="p" data-group-id="7704681582-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="0193224384-5">(</span><span class="n">N</span><span class="p" data-group-id="0193224384-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="0193224384-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="0193224384-6">)</span><span class="p">.</span></code></pre><p>So this is a module, called <code class="inline">tut1</code> that contains a function called <code class="inline">fac&gt;</code>, which
│ │ │ -takes one argument, <code class="inline">N</code>.</p><p>The first part says that the factorial of 1 is 1.:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="8785484686-1">(</span><span class="mi">1</span><span class="p" data-group-id="8785484686-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="7704681582-5">(</span><span class="n">N</span><span class="p" data-group-id="7704681582-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="7704681582-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7704681582-6">)</span><span class="p">.</span></code></pre><p>So this is a module, called <code class="inline">tut1</code> that contains a function called <code class="inline">fac&gt;</code>, which
│ │ │ +takes one argument, <code class="inline">N</code>.</p><p>The first part says that the factorial of 1 is 1.:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="1851067613-1">(</span><span class="mi">1</span><span class="p" data-group-id="1851067613-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="mi">1</span><span class="p">;</span></code></pre><p>Notice that this part ends with a semicolon <code class="inline">;</code> that indicates that there is
│ │ │  more of the function <code class="inline">fac&gt;</code> to come.</p><p>The second part says that the factorial of N is N multiplied by the factorial of
│ │ │ -N - 1:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="7450400121-1">(</span><span class="n">N</span><span class="p" data-group-id="7450400121-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="7450400121-2">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7450400121-2">)</span><span class="p">.</span></code></pre><p>Notice that this part ends with a <code class="inline">.</code> saying that there are no more parts of
│ │ │ -this function.</p><p>Compile the file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="1510768815-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="1510768815-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1510768815-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="1510768815-2">}</span></code></pre><p>And now calculate the factorial of 4.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">6&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">fac</span><span class="p" data-group-id="6046865830-1">(</span><span class="mi">4</span><span class="p" data-group-id="6046865830-1">)</span><span class="p">.</span><span class="w">
│ │ │ +N - 1:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fac</span><span class="p" data-group-id="7819950408-1">(</span><span class="n">N</span><span class="p" data-group-id="7819950408-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="7819950408-2">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7819950408-2">)</span><span class="p">.</span></code></pre><p>Notice that this part ends with a <code class="inline">.</code> saying that there are no more parts of
│ │ │ +this function.</p><p>Compile the file:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">5&gt; </span><span class="nf">c</span><span class="p" data-group-id="6387789657-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="6387789657-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6387789657-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="6387789657-2">}</span></code></pre><p>And now calculate the factorial of 4.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">6&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">fac</span><span class="p" data-group-id="1051606826-1">(</span><span class="mi">4</span><span class="p" data-group-id="1051606826-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">24</span></code></pre><p>Here the function <code class="inline">fac&gt;</code> in module <code class="inline">tut1</code> is called with argument <code class="inline">4</code>.</p><p>A function can have many arguments. Let us expand the module <code class="inline">tut1</code> with the
│ │ │ -function to multiply two numbers:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1066818501-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="1066818501-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1066818501-2">(</span><span class="p" data-group-id="1066818501-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">mult</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1066818501-3">]</span><span class="p" data-group-id="1066818501-2">)</span><span class="p">.</span><span class="w">
│ │ │ +function to multiply two numbers:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1828751140-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="1828751140-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1828751140-2">(</span><span class="p" data-group-id="1828751140-3">[</span><span class="ss">fac</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">mult</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1828751140-3">]</span><span class="p" data-group-id="1828751140-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="1066818501-4">(</span><span class="mi">1</span><span class="p" data-group-id="1066818501-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="1828751140-4">(</span><span class="mi">1</span><span class="p" data-group-id="1828751140-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">fac</span><span class="p" data-group-id="1066818501-5">(</span><span class="n">N</span><span class="p" data-group-id="1066818501-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="1066818501-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="1066818501-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">fac</span><span class="p" data-group-id="1828751140-5">(</span><span class="n">N</span><span class="p" data-group-id="1828751140-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="nf">fac</span><span class="p" data-group-id="1828751140-6">(</span><span class="n">N</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="1828751140-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">mult</span><span class="p" data-group-id="1066818501-7">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1066818501-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">mult</span><span class="p" data-group-id="1828751140-7">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1828751140-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span></code></pre><p>Notice that it is also required to expand the <code class="inline">-export</code> line with the
│ │ │ -information that there is another function <code class="inline">mult</code> with two arguments.</p><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nf">c</span><span class="p" data-group-id="4163189501-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="4163189501-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4163189501-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="4163189501-2">}</span></code></pre><p>Try out the new function <code class="inline">mult</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">8&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">mult</span><span class="p" data-group-id="2374758720-1">(</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2374758720-1">)</span><span class="p">.</span><span class="w">
│ │ │ +information that there is another function <code class="inline">mult</code> with two arguments.</p><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">7&gt; </span><span class="nf">c</span><span class="p" data-group-id="4276997535-1">(</span><span class="ss">tut1</span><span class="p" data-group-id="4276997535-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4276997535-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut1</span><span class="p" data-group-id="4276997535-2">}</span></code></pre><p>Try out the new function <code class="inline">mult</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">8&gt; </span><span class="nc">tut1</span><span class="p">:</span><span class="nf">mult</span><span class="p" data-group-id="2651134013-1">(</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2651134013-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">12</span></code></pre><p>In this example the numbers are integers and the arguments in the functions in
│ │ │  the code <code class="inline">N</code>, <code class="inline">X</code>, and <code class="inline">Y</code> are called variables. Variables must start with a
│ │ │  capital letter (see <a href="../../doc/system/expressions.html">Variables</a>). Examples of
│ │ │  variables are <code class="inline">Number</code>, <code class="inline">ShoeSize</code>, and <code class="inline">Age</code>.</p><h2 id="atoms" class="section-heading">
│ │ │    <a href="#atoms" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Atoms</span>
│ │ │  </h2>
│ │ │  <p>Atom is another data type in Erlang. Atoms start with a small letter (see
│ │ │  <a href="../../doc/system/data_types.html">Atom</a>), for example, <code class="inline">charles</code>, <code class="inline">centimeter</code>, and
│ │ │  <code class="inline">inch</code>. Atoms are simply names, nothing else. They are not like variables, which
│ │ │  can have a value.</p><p>Enter the next program in a file named <code class="inline">tut2.erl</code>). It can be useful for
│ │ │ -converting from inches to centimeters and conversely:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8372852472-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="8372852472-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8372852472-2">(</span><span class="p" data-group-id="8372852472-3">[</span><span class="ss">convert</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8372852472-3">]</span><span class="p" data-group-id="8372852472-2">)</span><span class="p">.</span><span class="w">
│ │ │ +converting from inches to centimeters and conversely:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1080728377-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="1080728377-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1080728377-2">(</span><span class="p" data-group-id="1080728377-3">[</span><span class="ss">convert</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1080728377-3">]</span><span class="p" data-group-id="1080728377-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">convert</span><span class="p" data-group-id="8372852472-4">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="8372852472-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">convert</span><span class="p" data-group-id="1080728377-4">(</span><span class="n">M</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="1080728377-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">M</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">convert</span><span class="p" data-group-id="8372852472-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="8372852472-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p">.</span></code></pre><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nf">c</span><span class="p" data-group-id="6285781849-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="6285781849-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6285781849-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut2</span><span class="p" data-group-id="6285781849-2">}</span></code></pre><p>Test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">10&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="5390082653-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="5390082653-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">convert</span><span class="p" data-group-id="1080728377-5">(</span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="1080728377-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">N</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p">.</span></code></pre><p>Compile:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">9&gt; </span><span class="nf">c</span><span class="p" data-group-id="6773083036-1">(</span><span class="ss">tut2</span><span class="p" data-group-id="6773083036-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6773083036-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut2</span><span class="p" data-group-id="6773083036-2">}</span></code></pre><p>Test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">10&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="9849403019-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="9849403019-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">1.1811023622047243</span><span class="gp unselectable">
│ │ │ -11&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="5390082653-2">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="5390082653-2">)</span><span class="p">.</span><span class="w">
│ │ │ +11&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="9849403019-2">(</span><span class="mi">7</span><span class="p">,</span><span class="w"> </span><span class="ss">centimeter</span><span class="p" data-group-id="9849403019-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">17.78</span></code></pre><p>Notice the introduction of decimals (floating point numbers) without any
│ │ │  explanation. Hopefully you can cope with that.</p><p>Let us see what happens if something other than <code class="inline">centimeter</code> or <code class="inline">inch</code> is
│ │ │ -entered in the <code class="inline">convert</code> function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">12&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="8261127725-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">miles</span><span class="p" data-group-id="8261127725-1">)</span><span class="p">.</span><span class="w">
│ │ │ +entered in the <code class="inline">convert</code> function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">12&gt; </span><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="5439099541-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">miles</span><span class="p" data-group-id="5439099541-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no function clause matching tut2:convert(3,miles) (tut2.erl, line 4)</span></code></pre><p>The two parts of the <code class="inline">convert</code> function are called its clauses. As shown,
│ │ │  <code class="inline">miles</code> is not part of either of the clauses. The Erlang system cannot <em>match</em>
│ │ │  either of the clauses so an error message <code class="inline">function_clause</code> is returned. The
│ │ │  shell formats the error message nicely, but the error tuple is saved in the
│ │ │ -shell's history list and can be output by the shell command <code class="inline">v/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">13&gt; </span><span class="nf">v</span><span class="p" data-group-id="2542103670-1">(</span><span class="mi">12</span><span class="p" data-group-id="2542103670-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2542103670-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="2542103670-3">{</span><span class="ss">function_clause</span><span class="p">,</span><span class="p" data-group-id="2542103670-4">[</span><span class="p" data-group-id="2542103670-5">{</span><span class="ss">tut2</span><span class="p">,</span><span class="ss">convert</span><span class="p">,</span><span class="w">
│ │ │ -                                </span><span class="p" data-group-id="2542103670-6">[</span><span class="mi">3</span><span class="p">,</span><span class="ss">miles</span><span class="p" data-group-id="2542103670-6">]</span><span class="p">,</span><span class="w">
│ │ │ -                                </span><span class="p" data-group-id="2542103670-7">[</span><span class="p" data-group-id="2542103670-8">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;tut2.erl&quot;</span><span class="p" data-group-id="2542103670-8">}</span><span class="p">,</span><span class="p" data-group-id="2542103670-9">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2542103670-9">}</span><span class="p" data-group-id="2542103670-7">]</span><span class="p" data-group-id="2542103670-5">}</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="p" data-group-id="2542103670-10">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="p" data-group-id="2542103670-11">[</span><span class="p" data-group-id="2542103670-12">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="2542103670-12">}</span><span class="p">,</span><span class="p" data-group-id="2542103670-13">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">677</span><span class="p" data-group-id="2542103670-13">}</span><span class="p" data-group-id="2542103670-11">]</span><span class="p" data-group-id="2542103670-10">}</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="p" data-group-id="2542103670-14">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="2542103670-15">[</span><span class="p" data-group-id="2542103670-16">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="2542103670-16">}</span><span class="p">,</span><span class="p" data-group-id="2542103670-17">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">687</span><span class="p" data-group-id="2542103670-17">}</span><span class="p" data-group-id="2542103670-15">]</span><span class="p" data-group-id="2542103670-14">}</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="p" data-group-id="2542103670-18">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="2542103670-19">[</span><span class="p" data-group-id="2542103670-20">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="2542103670-20">}</span><span class="p">,</span><span class="p" data-group-id="2542103670-21">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">642</span><span class="p" data-group-id="2542103670-21">}</span><span class="p" data-group-id="2542103670-19">]</span><span class="p" data-group-id="2542103670-18">}</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="p" data-group-id="2542103670-22">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_loop</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                                 </span><span class="p" data-group-id="2542103670-23">[</span><span class="p" data-group-id="2542103670-24">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="2542103670-24">}</span><span class="p">,</span><span class="p" data-group-id="2542103670-25">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">627</span><span class="p" data-group-id="2542103670-25">}</span><span class="p" data-group-id="2542103670-23">]</span><span class="p" data-group-id="2542103670-22">}</span><span class="p" data-group-id="2542103670-4">]</span><span class="p" data-group-id="2542103670-3">}</span><span class="p" data-group-id="2542103670-2">}</span></code></pre><h2 id="tuples" class="section-heading">
│ │ │ +shell's history list and can be output by the shell command <code class="inline">v/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">13&gt; </span><span class="nf">v</span><span class="p" data-group-id="0854806409-1">(</span><span class="mi">12</span><span class="p" data-group-id="0854806409-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0854806409-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="0854806409-3">{</span><span class="ss">function_clause</span><span class="p">,</span><span class="p" data-group-id="0854806409-4">[</span><span class="p" data-group-id="0854806409-5">{</span><span class="ss">tut2</span><span class="p">,</span><span class="ss">convert</span><span class="p">,</span><span class="w">
│ │ │ +                                </span><span class="p" data-group-id="0854806409-6">[</span><span class="mi">3</span><span class="p">,</span><span class="ss">miles</span><span class="p" data-group-id="0854806409-6">]</span><span class="p">,</span><span class="w">
│ │ │ +                                </span><span class="p" data-group-id="0854806409-7">[</span><span class="p" data-group-id="0854806409-8">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;tut2.erl&quot;</span><span class="p" data-group-id="0854806409-8">}</span><span class="p">,</span><span class="p" data-group-id="0854806409-9">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0854806409-9">}</span><span class="p" data-group-id="0854806409-7">]</span><span class="p" data-group-id="0854806409-5">}</span><span class="p">,</span><span class="w">
│ │ │ +                          </span><span class="p" data-group-id="0854806409-10">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="p" data-group-id="0854806409-11">[</span><span class="p" data-group-id="0854806409-12">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="0854806409-12">}</span><span class="p">,</span><span class="p" data-group-id="0854806409-13">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">677</span><span class="p" data-group-id="0854806409-13">}</span><span class="p" data-group-id="0854806409-11">]</span><span class="p" data-group-id="0854806409-10">}</span><span class="p">,</span><span class="w">
│ │ │ +                          </span><span class="p" data-group-id="0854806409-14">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="0854806409-15">[</span><span class="p" data-group-id="0854806409-16">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="0854806409-16">}</span><span class="p">,</span><span class="p" data-group-id="0854806409-17">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">687</span><span class="p" data-group-id="0854806409-17">}</span><span class="p" data-group-id="0854806409-15">]</span><span class="p" data-group-id="0854806409-14">}</span><span class="p">,</span><span class="w">
│ │ │ +                          </span><span class="p" data-group-id="0854806409-18">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="0854806409-19">[</span><span class="p" data-group-id="0854806409-20">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="0854806409-20">}</span><span class="p">,</span><span class="p" data-group-id="0854806409-21">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">642</span><span class="p" data-group-id="0854806409-21">}</span><span class="p" data-group-id="0854806409-19">]</span><span class="p" data-group-id="0854806409-18">}</span><span class="p">,</span><span class="w">
│ │ │ +                          </span><span class="p" data-group-id="0854806409-22">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_loop</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                                 </span><span class="p" data-group-id="0854806409-23">[</span><span class="p" data-group-id="0854806409-24">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="0854806409-24">}</span><span class="p">,</span><span class="p" data-group-id="0854806409-25">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">627</span><span class="p" data-group-id="0854806409-25">}</span><span class="p" data-group-id="0854806409-23">]</span><span class="p" data-group-id="0854806409-22">}</span><span class="p" data-group-id="0854806409-4">]</span><span class="p" data-group-id="0854806409-3">}</span><span class="p" data-group-id="0854806409-2">}</span></code></pre><h2 id="tuples" class="section-heading">
│ │ │    <a href="#tuples" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Tuples</span>
│ │ │  </h2>
│ │ │ -<p>Now the <code class="inline">tut2</code> program is hardly good programming style. Consider:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="3685022172-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="3685022172-1">)</span><span class="p">.</span></code></pre><p>Does this mean that 3 is in inches? Or does it mean that 3 is in centimeters and
│ │ │ +<p>Now the <code class="inline">tut2</code> program is hardly good programming style. Consider:</p><pre><code class="makeup erlang" translate="no"><span class="nc">tut2</span><span class="p">:</span><span class="nf">convert</span><span class="p" data-group-id="8747820375-1">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">inch</span><span class="p" data-group-id="8747820375-1">)</span><span class="p">.</span></code></pre><p>Does this mean that 3 is in inches? Or does it mean that 3 is in centimeters and
│ │ │  is to be converted to inches? Erlang has a way to group things together to make
│ │ │  things more understandable. These are called <em>tuples</em> and are surrounded by
│ │ │  curly brackets, <code class="inline">{</code> and <code class="inline">}</code>.</p><p>So, <code class="inline">{inch,3}</code> denotes 3 inches and <code class="inline">{centimeter,5}</code> denotes 5 centimeters. Now
│ │ │  let us write a new program that converts centimeters to inches and conversely.
│ │ │ -Enter the following code in a file called <code class="inline">tut3.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3877376034-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="3877376034-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3877376034-2">(</span><span class="p" data-group-id="3877376034-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3877376034-3">]</span><span class="p" data-group-id="3877376034-2">)</span><span class="p">.</span><span class="w">
│ │ │ +Enter the following code in a file called <code class="inline">tut3.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2368475018-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="2368475018-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2368475018-2">(</span><span class="p" data-group-id="2368475018-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2368475018-3">]</span><span class="p" data-group-id="2368475018-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="3877376034-4">(</span><span class="p" data-group-id="3877376034-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3877376034-5">}</span><span class="p" data-group-id="3877376034-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3877376034-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="3877376034-6">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="3877376034-7">(</span><span class="p" data-group-id="3877376034-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3877376034-8">}</span><span class="p" data-group-id="3877376034-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3877376034-9">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="3877376034-9">}</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">14&gt; </span><span class="nf">c</span><span class="p" data-group-id="6022314551-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="6022314551-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6022314551-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut3</span><span class="p" data-group-id="6022314551-2">}</span><span class="gp unselectable">
│ │ │ -15&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="6022314551-3">(</span><span class="p" data-group-id="6022314551-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="6022314551-4">}</span><span class="p" data-group-id="6022314551-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6022314551-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">12.7</span><span class="p" data-group-id="6022314551-5">}</span><span class="gp unselectable">
│ │ │ -16&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="6022314551-6">(</span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="6022314551-7">(</span><span class="p" data-group-id="6022314551-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="6022314551-8">}</span><span class="p" data-group-id="6022314551-7">)</span><span class="p" data-group-id="6022314551-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6022314551-9">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">5.0</span><span class="p" data-group-id="6022314551-9">}</span></code></pre><p>Notice on line 16 that 5 inches is converted to centimeters and back again and
│ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="2368475018-4">(</span><span class="p" data-group-id="2368475018-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="2368475018-5">}</span><span class="p" data-group-id="2368475018-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2368475018-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="2368475018-6">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="2368475018-7">(</span><span class="p" data-group-id="2368475018-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="2368475018-8">}</span><span class="p" data-group-id="2368475018-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2368475018-9">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="2368475018-9">}</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">14&gt; </span><span class="nf">c</span><span class="p" data-group-id="5298186802-1">(</span><span class="ss">tut3</span><span class="p" data-group-id="5298186802-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5298186802-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut3</span><span class="p" data-group-id="5298186802-2">}</span><span class="gp unselectable">
│ │ │ +15&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5298186802-3">(</span><span class="p" data-group-id="5298186802-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="5298186802-4">}</span><span class="p" data-group-id="5298186802-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5298186802-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">12.7</span><span class="p" data-group-id="5298186802-5">}</span><span class="gp unselectable">
│ │ │ +16&gt; </span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5298186802-6">(</span><span class="nc">tut3</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="5298186802-7">(</span><span class="p" data-group-id="5298186802-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="5298186802-8">}</span><span class="p" data-group-id="5298186802-7">)</span><span class="p" data-group-id="5298186802-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5298186802-9">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">5.0</span><span class="p" data-group-id="5298186802-9">}</span></code></pre><p>Notice on line 16 that 5 inches is converted to centimeters and back again and
│ │ │  reassuringly get back to the original value. That is, the argument to a function
│ │ │  can be the result of another function. Consider how line 16 (above) works. The
│ │ │  argument given to the function <code class="inline">{inch,5}</code> is first matched against the first
│ │ │  head clause of <code class="inline">convert_length</code>, that is, <code class="inline">convert_length({centimeter,X})</code>. It
│ │ │  can be seen that <code class="inline">{centimeter,X}</code> does not match <code class="inline">{inch,5}</code> (the head is the bit
│ │ │  before the <code class="inline">-&gt;</code>). This having failed, let us try the head of the next clause
│ │ │  that is, <code class="inline">convert_length({inch,Y})</code>. This matches, and <code class="inline">Y</code> gets the value 5.</p><p>Tuples can have more than two parts, in fact as many parts as you want, and
│ │ │  contain any valid Erlang <em>term</em>. For example, to represent the temperature of
│ │ │ -various cities of the world:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="4163462685-1">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4163462685-2">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="4163462685-2">}</span><span class="p" data-group-id="4163462685-1">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4163462685-3">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4163462685-4">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="4163462685-4">}</span><span class="p" data-group-id="4163462685-3">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4163462685-5">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4163462685-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="4163462685-6">}</span><span class="p" data-group-id="4163462685-5">}</span></code></pre><p>Tuples have a fixed number of items in them. Each item in a tuple is called an
│ │ │ +various cities of the world:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1706214084-1">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1706214084-2">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="1706214084-2">}</span><span class="p" data-group-id="1706214084-1">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1706214084-3">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1706214084-4">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="1706214084-4">}</span><span class="p" data-group-id="1706214084-3">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1706214084-5">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1706214084-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="1706214084-6">}</span><span class="p" data-group-id="1706214084-5">}</span></code></pre><p>Tuples have a fixed number of items in them. Each item in a tuple is called an
│ │ │  <em>element</em>. In the tuple <code class="inline">{moscow,{c,-10}}</code>, element 1 is <code class="inline">moscow</code> and element 2
│ │ │  is <code class="inline">{c,-10}</code>. Here <code class="inline">c</code> represents Celsius and <code class="inline">f</code> Fahrenheit.</p><h2 id="lists" class="section-heading">
│ │ │    <a href="#lists" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Lists</span>
│ │ │  </h2>
│ │ │  <p>Whereas tuples group things together, it is also needed to represent lists of
│ │ │  things. Lists in Erlang are surrounded by square brackets, <code class="inline">[</code> and <code class="inline">]</code>. For
│ │ │ -example, a list of the temperatures of various cities in the world can be:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7935751074-1">[</span><span class="p" data-group-id="7935751074-2">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="7935751074-3">}</span><span class="p" data-group-id="7935751074-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-4">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-5">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="7935751074-5">}</span><span class="p" data-group-id="7935751074-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-6">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-7">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="7935751074-7">}</span><span class="p" data-group-id="7935751074-6">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="7935751074-8">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="7935751074-9">}</span><span class="p" data-group-id="7935751074-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-10">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7935751074-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="7935751074-11">}</span><span class="p" data-group-id="7935751074-10">}</span><span class="p" data-group-id="7935751074-1">]</span></code></pre><p>Notice that this list was so long that it did not fit on one line. This does not
│ │ │ +example, a list of the temperatures of various cities in the world can be:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6325286880-1">[</span><span class="p" data-group-id="6325286880-2">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="6325286880-3">}</span><span class="p" data-group-id="6325286880-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-4">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-5">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="6325286880-5">}</span><span class="p" data-group-id="6325286880-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-6">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-7">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="6325286880-7">}</span><span class="p" data-group-id="6325286880-6">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="6325286880-8">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="6325286880-9">}</span><span class="p" data-group-id="6325286880-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-10">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6325286880-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="6325286880-11">}</span><span class="p" data-group-id="6325286880-10">}</span><span class="p" data-group-id="6325286880-1">]</span></code></pre><p>Notice that this list was so long that it did not fit on one line. This does not
│ │ │  matter, Erlang allows line breaks at all &quot;sensible places&quot; but not, for example,
│ │ │  in the middle of atoms, integers, and others.</p><p>A useful way of looking at parts of lists, is by using <code class="inline">|</code>. This is best
│ │ │ -explained by an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">17&gt; </span><span class="p" data-group-id="5438157222-1">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="n">TheRest</span><span class="p" data-group-id="5438157222-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5438157222-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5438157222-2">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5438157222-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5438157222-3">]</span><span class="gp unselectable">
│ │ │ +explained by an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">17&gt; </span><span class="p" data-group-id="8203707780-1">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="n">TheRest</span><span class="p" data-group-id="8203707780-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8203707780-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8203707780-2">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8203707780-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8203707780-3">]</span><span class="gp unselectable">
│ │ │  18&gt; </span><span class="n">First</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │  19&gt; </span><span class="n">TheRest</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5438157222-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5438157222-4">]</span></code></pre><p>To separate the first elements of the list from the rest of the list, <code class="inline">|</code> is
│ │ │ -used. <code class="inline">First</code> has got value <code class="inline">1</code> and <code class="inline">TheRest</code> has got the value <code class="inline">[2,3,4,5]</code>.</p><p>Another example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">20&gt; </span><span class="p" data-group-id="5369111526-1">[</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">R</span><span class="p" data-group-id="5369111526-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5369111526-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="5369111526-2">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5369111526-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="5369111526-3">]</span><span class="gp unselectable">
│ │ │ +</span><span class="p" data-group-id="8203707780-4">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8203707780-4">]</span></code></pre><p>To separate the first elements of the list from the rest of the list, <code class="inline">|</code> is
│ │ │ +used. <code class="inline">First</code> has got value <code class="inline">1</code> and <code class="inline">TheRest</code> has got the value <code class="inline">[2,3,4,5]</code>.</p><p>Another example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">20&gt; </span><span class="p" data-group-id="4229904966-1">[</span><span class="n">E1</span><span class="p">,</span><span class="w"> </span><span class="n">E2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">R</span><span class="p" data-group-id="4229904966-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4229904966-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="4229904966-2">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4229904966-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="4229904966-3">]</span><span class="gp unselectable">
│ │ │  21&gt; </span><span class="n">E1</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │  22&gt; </span><span class="n">E2</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">2</span><span class="gp unselectable">
│ │ │  23&gt; </span><span class="n">R</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5369111526-4">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="5369111526-4">]</span></code></pre><p>Here you see the use of <code class="inline">|</code> to get the first two elements from the list. If you
│ │ │ +</span><span class="p" data-group-id="4229904966-4">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="4229904966-4">]</span></code></pre><p>Here you see the use of <code class="inline">|</code> to get the first two elements from the list. If you
│ │ │  try to get more elements from the list than there are elements in the list, an
│ │ │  error is returned. Notice also the special case of the list with no elements,
│ │ │ -<code class="inline">[]</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">24&gt; </span><span class="p" data-group-id="3000130627-1">[</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="3000130627-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3000130627-2">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3000130627-2">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3000130627-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3000130627-3">]</span><span class="gp unselectable">
│ │ │ +<code class="inline">[]</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">24&gt; </span><span class="p" data-group-id="6606651659-1">[</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">C</span><span class="p" data-group-id="6606651659-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6606651659-2">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6606651659-2">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6606651659-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="6606651659-3">]</span><span class="gp unselectable">
│ │ │  25&gt; </span><span class="n">A</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │  26&gt; </span><span class="n">B</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">2</span><span class="gp unselectable">
│ │ │  27&gt; </span><span class="n">C</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3000130627-4">[</span><span class="p" data-group-id="3000130627-4">]</span></code></pre><p>In the previous examples, new variable names are used, instead of reusing the
│ │ │ +</span><span class="p" data-group-id="6606651659-4">[</span><span class="p" data-group-id="6606651659-4">]</span></code></pre><p>In the previous examples, new variable names are used, instead of reusing the
│ │ │  old ones: <code class="inline">First</code>, <code class="inline">TheRest</code>, <code class="inline">E1</code>, <code class="inline">E2</code>, <code class="inline">R</code>, <code class="inline">A</code>, <code class="inline">B</code>, and <code class="inline">C</code>. The reason for
│ │ │  this is that a variable can only be given a value once in its context (scope).
│ │ │  More about this later.</p><p>The following example shows how to find the length of a list. Enter the
│ │ │ -following code in a file named <code class="inline">tut4.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6021144325-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="6021144325-1">)</span><span class="p">.</span><span class="w">
│ │ │ +following code in a file named <code class="inline">tut4.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2932919944-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="2932919944-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6021144325-2">(</span><span class="p" data-group-id="6021144325-3">[</span><span class="ss">list_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6021144325-3">]</span><span class="p" data-group-id="6021144325-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2932919944-2">(</span><span class="p" data-group-id="2932919944-3">[</span><span class="ss">list_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2932919944-3">]</span><span class="p" data-group-id="2932919944-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">list_length</span><span class="p" data-group-id="6021144325-4">(</span><span class="p" data-group-id="6021144325-5">[</span><span class="p" data-group-id="6021144325-5">]</span><span class="p" data-group-id="6021144325-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">list_length</span><span class="p" data-group-id="2932919944-4">(</span><span class="p" data-group-id="2932919944-5">[</span><span class="p" data-group-id="2932919944-5">]</span><span class="p" data-group-id="2932919944-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="mi">0</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">list_length</span><span class="p" data-group-id="6021144325-6">(</span><span class="p" data-group-id="6021144325-7">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6021144325-7">]</span><span class="p" data-group-id="6021144325-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="6021144325-8">(</span><span class="n">Rest</span><span class="p" data-group-id="6021144325-8">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">28&gt; </span><span class="nf">c</span><span class="p" data-group-id="6924450651-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="6924450651-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6924450651-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut4</span><span class="p" data-group-id="6924450651-2">}</span><span class="gp unselectable">
│ │ │ -29&gt; </span><span class="nc">tut4</span><span class="p">:</span><span class="nf">list_length</span><span class="p" data-group-id="6924450651-3">(</span><span class="p" data-group-id="6924450651-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="6924450651-4">]</span><span class="p" data-group-id="6924450651-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">7</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="4826328305-1">(</span><span class="p" data-group-id="4826328305-2">[</span><span class="p" data-group-id="4826328305-2">]</span><span class="p" data-group-id="4826328305-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="mi">0</span><span class="p">;</span></code></pre><p>The length of an empty list is obviously 0.</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="1429240031-1">(</span><span class="p" data-group-id="1429240031-2">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="1429240031-2">]</span><span class="p" data-group-id="1429240031-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="1429240031-3">(</span><span class="n">Rest</span><span class="p" data-group-id="1429240031-3">)</span><span class="p">.</span></code></pre><p>The length of a list with the first element <code class="inline">First</code> and the remaining elements
│ │ │ +</span><span class="nf">list_length</span><span class="p" data-group-id="2932919944-6">(</span><span class="p" data-group-id="2932919944-7">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="2932919944-7">]</span><span class="p" data-group-id="2932919944-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="2932919944-8">(</span><span class="n">Rest</span><span class="p" data-group-id="2932919944-8">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">28&gt; </span><span class="nf">c</span><span class="p" data-group-id="5750221459-1">(</span><span class="ss">tut4</span><span class="p" data-group-id="5750221459-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5750221459-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut4</span><span class="p" data-group-id="5750221459-2">}</span><span class="gp unselectable">
│ │ │ +29&gt; </span><span class="nc">tut4</span><span class="p">:</span><span class="nf">list_length</span><span class="p" data-group-id="5750221459-3">(</span><span class="p" data-group-id="5750221459-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="5750221459-4">]</span><span class="p" data-group-id="5750221459-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">7</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="0817836242-1">(</span><span class="p" data-group-id="0817836242-2">[</span><span class="p" data-group-id="0817836242-2">]</span><span class="p" data-group-id="0817836242-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="mi">0</span><span class="p">;</span></code></pre><p>The length of an empty list is obviously 0.</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_length</span><span class="p" data-group-id="3165834782-1">(</span><span class="p" data-group-id="3165834782-2">[</span><span class="n">First</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="3165834782-2">]</span><span class="p" data-group-id="3165834782-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="nf">list_length</span><span class="p" data-group-id="3165834782-3">(</span><span class="n">Rest</span><span class="p" data-group-id="3165834782-3">)</span><span class="p">.</span></code></pre><p>The length of a list with the first element <code class="inline">First</code> and the remaining elements
│ │ │  <code class="inline">Rest</code> is 1 + the length of <code class="inline">Rest</code>.</p><p>(Advanced readers only: This is not tail recursive, there is a better way to
│ │ │  write this function.)</p><p>In general, tuples are used where &quot;records&quot; or &quot;structs&quot; are used in other
│ │ │  languages. Also, lists are used when representing things with varying sizes,
│ │ │  that is, where linked lists are used in other languages.</p><p>Erlang does not have a string data type. Instead, strings can be represented by
│ │ │  lists of Unicode characters. This implies for example that the list <code class="inline">[97,98,99]</code>
│ │ │  is equivalent to <code class="inline">&quot;abc&quot;</code>. The Erlang shell is &quot;clever&quot; and guesses what list you
│ │ │ -mean and outputs it in what it thinks is the most appropriate form, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">30&gt; </span><span class="p" data-group-id="5364750314-1">[</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="5364750314-1">]</span><span class="p">.</span><span class="w">
│ │ │ +mean and outputs it in what it thinks is the most appropriate form, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">30&gt; </span><span class="p" data-group-id="8530392512-1">[</span><span class="mi">97</span><span class="p">,</span><span class="mi">98</span><span class="p">,</span><span class="mi">99</span><span class="p" data-group-id="8530392512-1">]</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;abc&quot;</span></code></pre><h2 id="maps" class="section-heading">
│ │ │    <a href="#maps" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Maps</span>
│ │ │  </h2>
│ │ │  <p>Maps are a set of key to value associations. These associations are encapsulated
│ │ │ -with <code class="inline">#{</code> and <code class="inline">}</code>. To create an association from <code class="inline">&quot;key&quot;</code> to value <code class="inline">42</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="4442170088-1">#{</span><span class="w"> </span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p" data-group-id="4442170088-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4442170088-2">#{</span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="4442170088-2">}</span></code></pre><p>Let us jump straight into the deep end with an example using some interesting
│ │ │ +with <code class="inline">#{</code> and <code class="inline">}</code>. To create an association from <code class="inline">&quot;key&quot;</code> to value <code class="inline">42</code>:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="4131177784-1">#{</span><span class="w"> </span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p" data-group-id="4131177784-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4131177784-2">#{</span><span class="s">&quot;key&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">42</span><span class="p" data-group-id="4131177784-2">}</span></code></pre><p>Let us jump straight into the deep end with an example using some interesting
│ │ │  features.</p><p>The following example shows how to calculate alpha blending using maps to
│ │ │ -reference color and alpha channels. Enter the code in a file named <code class="inline">color.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9600024716-1">(</span><span class="ss">color</span><span class="p" data-group-id="9600024716-1">)</span><span class="p">.</span><span class="w">
│ │ │ +reference color and alpha channels. Enter the code in a file named <code class="inline">color.erl</code>):</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2041589334-1">(</span><span class="ss">color</span><span class="p" data-group-id="2041589334-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9600024716-2">(</span><span class="p" data-group-id="9600024716-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="ss">blend</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9600024716-3">]</span><span class="p" data-group-id="9600024716-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2041589334-2">(</span><span class="p" data-group-id="2041589334-3">[</span><span class="ss">new</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="ss">blend</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="2041589334-3">]</span><span class="p" data-group-id="2041589334-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9600024716-4">(</span><span class="nf">is_channel</span><span class="p" data-group-id="9600024716-5">(</span><span class="n">V</span><span class="p" data-group-id="9600024716-5">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9600024716-6">(</span><span class="nf">is_float</span><span class="p" data-group-id="9600024716-7">(</span><span class="n">V</span><span class="p" data-group-id="9600024716-7">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="9600024716-6">)</span><span class="p" data-group-id="9600024716-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2041589334-4">(</span><span class="nf">is_channel</span><span class="p" data-group-id="2041589334-5">(</span><span class="n">V</span><span class="p" data-group-id="2041589334-5">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2041589334-6">(</span><span class="nf">is_float</span><span class="p" data-group-id="2041589334-7">(</span><span class="n">V</span><span class="p" data-group-id="2041589334-7">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="2041589334-6">)</span><span class="p" data-group-id="2041589334-4">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">new</span><span class="p" data-group-id="9600024716-8">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="9600024716-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9600024716-9">(</span><span class="n">R</span><span class="p" data-group-id="9600024716-9">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9600024716-10">(</span><span class="n">G</span><span class="p" data-group-id="9600024716-10">)</span><span class="p">,</span><span class="w">
│ │ │ -                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9600024716-11">(</span><span class="n">B</span><span class="p" data-group-id="9600024716-11">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="9600024716-12">(</span><span class="n">A</span><span class="p" data-group-id="9600024716-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9600024716-13">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="9600024716-13">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">blend</span><span class="p" data-group-id="9600024716-14">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9600024716-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">blend</span><span class="p" data-group-id="9600024716-15">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="nf">alpha</span><span class="p" data-group-id="9600024716-16">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9600024716-16">)</span><span class="p" data-group-id="9600024716-15">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">blend</span><span class="p" data-group-id="9600024716-17">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="9600024716-17">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Dst</span><span class="p" data-group-id="9600024716-18">#{</span><span class="w">
│ │ │ -        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="9600024716-19">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9600024716-19">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="9600024716-20">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9600024716-20">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="9600024716-21">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="9600024716-21">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">new</span><span class="p" data-group-id="2041589334-8">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="2041589334-8">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="2041589334-9">(</span><span class="n">R</span><span class="p" data-group-id="2041589334-9">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="2041589334-10">(</span><span class="n">G</span><span class="p" data-group-id="2041589334-10">)</span><span class="p">,</span><span class="w">
│ │ │ +                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="2041589334-11">(</span><span class="n">B</span><span class="p" data-group-id="2041589334-11">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="2041589334-12">(</span><span class="n">A</span><span class="p" data-group-id="2041589334-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2041589334-13">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="2041589334-13">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">blend</span><span class="p" data-group-id="2041589334-14">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2041589334-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">blend</span><span class="p" data-group-id="2041589334-15">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="nf">alpha</span><span class="p" data-group-id="2041589334-16">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2041589334-16">)</span><span class="p" data-group-id="2041589334-15">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">blend</span><span class="p" data-group-id="2041589334-17">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="2041589334-17">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Dst</span><span class="p" data-group-id="2041589334-18">#{</span><span class="w">
│ │ │ +        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="2041589334-19">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2041589334-19">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="2041589334-20">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2041589334-20">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="2041589334-21">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2041589334-21">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Alpha</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9600024716-18">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">blend</span><span class="p" data-group-id="9600024716-22">(</span><span class="p">_</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9600024716-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Dst</span><span class="p" data-group-id="9600024716-23">#{</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2041589334-18">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">blend</span><span class="p" data-group-id="2041589334-22">(</span><span class="p">_</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="2041589334-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Dst</span><span class="p" data-group-id="2041589334-23">#{</span><span class="w">
│ │ │          </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="mf">0.0</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9600024716-23">}</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2041589334-23">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">alpha</span><span class="p" data-group-id="9600024716-24">(</span><span class="p" data-group-id="9600024716-25">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9600024716-26">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="9600024716-26">}</span><span class="p" data-group-id="9600024716-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="9600024716-27">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-27">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">alpha</span><span class="p" data-group-id="2041589334-24">(</span><span class="p" data-group-id="2041589334-25">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-25">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2041589334-26">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="2041589334-26">}</span><span class="p" data-group-id="2041589334-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="2041589334-27">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-27">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">red</span><span class="p" data-group-id="9600024716-28">(</span><span class="p" data-group-id="9600024716-29">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-29">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9600024716-30">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="9600024716-30">}</span><span class="p" data-group-id="9600024716-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="9600024716-31">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-31">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">green</span><span class="p" data-group-id="9600024716-32">(</span><span class="p" data-group-id="9600024716-33">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-33">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9600024716-34">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="9600024716-34">}</span><span class="p" data-group-id="9600024716-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="9600024716-35">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-35">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">blue</span><span class="p" data-group-id="9600024716-36">(</span><span class="p" data-group-id="9600024716-37">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-37">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9600024716-38">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="9600024716-38">}</span><span class="p" data-group-id="9600024716-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="9600024716-39">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9600024716-39">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">c</span><span class="p" data-group-id="9945762886-1">(</span><span class="ss">color</span><span class="p" data-group-id="9945762886-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9945762886-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">color</span><span class="p" data-group-id="9945762886-2">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">C1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="9945762886-3">(</span><span class="mf">0.3</span><span class="p">,</span><span class="mf">0.4</span><span class="p">,</span><span class="mf">0.5</span><span class="p">,</span><span class="mf">1.0</span><span class="p" data-group-id="9945762886-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9945762886-4">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="9945762886-4">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">C2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="9945762886-5">(</span><span class="mf">1.0</span><span class="p">,</span><span class="mf">0.8</span><span class="p">,</span><span class="mf">0.1</span><span class="p">,</span><span class="mf">0.3</span><span class="p" data-group-id="9945762886-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9945762886-6">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.1</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.8</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="9945762886-6">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="9945762886-7">(</span><span class="n">C1</span><span class="p">,</span><span class="n">C2</span><span class="p" data-group-id="9945762886-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9945762886-8">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="9945762886-8">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="9945762886-9">(</span><span class="n">C2</span><span class="p">,</span><span class="n">C1</span><span class="p" data-group-id="9945762886-9">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9945762886-10">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.38</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.52</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.51</span><span class="p" data-group-id="9945762886-10">}</span></code></pre><p>This example warrants some explanation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9411340340-1">(</span><span class="nf">is_channel</span><span class="p" data-group-id="9411340340-2">(</span><span class="n">V</span><span class="p" data-group-id="9411340340-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9411340340-3">(</span><span class="nf">is_float</span><span class="p" data-group-id="9411340340-4">(</span><span class="n">V</span><span class="p" data-group-id="9411340340-4">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="9411340340-3">)</span><span class="p" data-group-id="9411340340-1">)</span><span class="p">.</span></code></pre><p>First a macro <code class="inline">is_channel</code> is defined to help with the guard tests. This is only
│ │ │ +</span><span class="nf">red</span><span class="p" data-group-id="2041589334-28">(</span><span class="p" data-group-id="2041589334-29">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-29">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2041589334-30">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="2041589334-30">}</span><span class="p" data-group-id="2041589334-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="2041589334-31">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-31">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">green</span><span class="p" data-group-id="2041589334-32">(</span><span class="p" data-group-id="2041589334-33">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-33">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2041589334-34">#{</span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="2041589334-34">}</span><span class="p" data-group-id="2041589334-32">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="2041589334-35">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-35">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">blue</span><span class="p" data-group-id="2041589334-36">(</span><span class="p" data-group-id="2041589334-37">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-37">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2041589334-38">#{</span><span class="ss">blue</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="2041589334-38">}</span><span class="p" data-group-id="2041589334-36">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="2041589334-39">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="2041589334-39">)</span><span class="p">.</span></code></pre><p>Compile and test:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">c</span><span class="p" data-group-id="6766775162-1">(</span><span class="ss">color</span><span class="p" data-group-id="6766775162-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6766775162-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">color</span><span class="p" data-group-id="6766775162-2">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">C1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="6766775162-3">(</span><span class="mf">0.3</span><span class="p">,</span><span class="mf">0.4</span><span class="p">,</span><span class="mf">0.5</span><span class="p">,</span><span class="mf">1.0</span><span class="p" data-group-id="6766775162-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6766775162-4">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="6766775162-4">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">C2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">color</span><span class="p">:</span><span class="nf">new</span><span class="p" data-group-id="6766775162-5">(</span><span class="mf">1.0</span><span class="p">,</span><span class="mf">0.8</span><span class="p">,</span><span class="mf">0.1</span><span class="p">,</span><span class="mf">0.3</span><span class="p" data-group-id="6766775162-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6766775162-6">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.1</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.8</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="6766775162-6">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="6766775162-7">(</span><span class="n">C1</span><span class="p">,</span><span class="n">C2</span><span class="p" data-group-id="6766775162-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6766775162-8">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.5</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.4</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.3</span><span class="p" data-group-id="6766775162-8">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nc">color</span><span class="p">:</span><span class="nf">blend</span><span class="p" data-group-id="6766775162-9">(</span><span class="n">C2</span><span class="p">,</span><span class="n">C1</span><span class="p" data-group-id="6766775162-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6766775162-10">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p">,</span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.38</span><span class="p">,</span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.52</span><span class="p">,</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mf">0.51</span><span class="p" data-group-id="6766775162-10">}</span></code></pre><p>This example warrants some explanation:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="8951137299-1">(</span><span class="nf">is_channel</span><span class="p" data-group-id="8951137299-2">(</span><span class="n">V</span><span class="p" data-group-id="8951137299-2">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8951137299-3">(</span><span class="nf">is_float</span><span class="p" data-group-id="8951137299-4">(</span><span class="n">V</span><span class="p" data-group-id="8951137299-4">)</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">&gt;=</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="8951137299-3">)</span><span class="p" data-group-id="8951137299-1">)</span><span class="p">.</span></code></pre><p>First a macro <code class="inline">is_channel</code> is defined to help with the guard tests. This is only
│ │ │  here for convenience and to reduce syntax cluttering. For more information about
│ │ │ -macros, see <a href="../../doc/system/macros.html">The Preprocessor</a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="4266556756-1">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="4266556756-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="4266556756-2">(</span><span class="n">R</span><span class="p" data-group-id="4266556756-2">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="4266556756-3">(</span><span class="n">G</span><span class="p" data-group-id="4266556756-3">)</span><span class="p">,</span><span class="w">
│ │ │ -                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="4266556756-4">(</span><span class="n">B</span><span class="p" data-group-id="4266556756-4">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="4266556756-5">(</span><span class="n">A</span><span class="p" data-group-id="4266556756-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4266556756-6">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="4266556756-6">}</span><span class="p">.</span></code></pre><p>The function <code class="inline">new/4</code> creates a new map term and lets the keys <code class="inline">red</code>, <code class="inline">green</code>,
│ │ │ +macros, see <a href="../../doc/system/macros.html">The Preprocessor</a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">new</span><span class="p" data-group-id="1606249006-1">(</span><span class="n">R</span><span class="p">,</span><span class="n">G</span><span class="p">,</span><span class="n">B</span><span class="p">,</span><span class="n">A</span><span class="p" data-group-id="1606249006-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="1606249006-2">(</span><span class="n">R</span><span class="p" data-group-id="1606249006-2">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="1606249006-3">(</span><span class="n">G</span><span class="p" data-group-id="1606249006-3">)</span><span class="p">,</span><span class="w">
│ │ │ +                  </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="1606249006-4">(</span><span class="n">B</span><span class="p" data-group-id="1606249006-4">)</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="nf">is_channel</span><span class="p" data-group-id="1606249006-5">(</span><span class="n">A</span><span class="p" data-group-id="1606249006-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1606249006-6">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">R</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">G</span><span class="p">,</span><span class="w"> </span><span class="ss">blue</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">A</span><span class="p" data-group-id="1606249006-6">}</span><span class="p">.</span></code></pre><p>The function <code class="inline">new/4</code> creates a new map term and lets the keys <code class="inline">red</code>, <code class="inline">green</code>,
│ │ │  <code class="inline">blue</code>, and <code class="inline">alpha</code> be associated with an initial value. In this case, only
│ │ │  float values between and including 0.0 and 1.0 are allowed, as ensured by the
│ │ │  <code class="inline">?is_channel/1</code> macro for each argument. Only the <code class="inline">=&gt;</code> operator is allowed when
│ │ │  creating a new map.</p><p>By calling <code class="inline">blend/2</code> on any color term created by <code class="inline">new/4</code>, the resulting color
│ │ │ -can be calculated as determined by the two map terms.</p><p>The first thing <code class="inline">blend/2</code> does is to calculate the resulting alpha channel:</p><pre><code class="makeup erlang" translate="no"><span class="nf">alpha</span><span class="p" data-group-id="5838568141-1">(</span><span class="p" data-group-id="5838568141-2">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="5838568141-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5838568141-3">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="5838568141-3">}</span><span class="p" data-group-id="5838568141-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="5838568141-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="5838568141-4">)</span><span class="p">.</span></code></pre><p>The value associated with key <code class="inline">alpha</code> is fetched for both arguments using the
│ │ │ +can be calculated as determined by the two map terms.</p><p>The first thing <code class="inline">blend/2</code> does is to calculate the resulting alpha channel:</p><pre><code class="makeup erlang" translate="no"><span class="nf">alpha</span><span class="p" data-group-id="3061969014-1">(</span><span class="p" data-group-id="3061969014-2">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3061969014-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3061969014-3">#{</span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="3061969014-3">}</span><span class="p" data-group-id="3061969014-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="3061969014-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="3061969014-4">)</span><span class="p">.</span></code></pre><p>The value associated with key <code class="inline">alpha</code> is fetched for both arguments using the
│ │ │  <code class="inline">:=</code> operator. The other keys in the map are ignored, only the key <code class="inline">alpha</code> is
│ │ │ -required and checked for.</p><p>This is also the case for functions <code class="inline">red/2</code>, <code class="inline">blue/2</code>, and <code class="inline">green/2</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">red</span><span class="p" data-group-id="6200275512-1">(</span><span class="p" data-group-id="6200275512-2">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="6200275512-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6200275512-3">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="6200275512-3">}</span><span class="p" data-group-id="6200275512-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="6200275512-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="6200275512-4">)</span><span class="p">.</span></code></pre><p>The difference here is that a check is made for two keys in each map argument.
│ │ │ -The other keys are ignored.</p><p>Finally, let us return the resulting color in <code class="inline">blend/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">blend</span><span class="p" data-group-id="2937899339-1">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="2937899339-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Dst</span><span class="p" data-group-id="2937899339-2">#{</span><span class="w">
│ │ │ -        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="2937899339-3">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2937899339-3">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="2937899339-4">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2937899339-4">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="2937899339-5">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="2937899339-5">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ +required and checked for.</p><p>This is also the case for functions <code class="inline">red/2</code>, <code class="inline">blue/2</code>, and <code class="inline">green/2</code>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">red</span><span class="p" data-group-id="9268053806-1">(</span><span class="p" data-group-id="9268053806-2">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9268053806-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9268053806-3">#{</span><span class="ss">red</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DV</span><span class="p">,</span><span class="w"> </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">DA</span><span class="p" data-group-id="9268053806-3">}</span><span class="p" data-group-id="9268053806-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SV</span><span class="o">*</span><span class="n">SA</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">DV</span><span class="o">*</span><span class="n">DA</span><span class="o">*</span><span class="p" data-group-id="9268053806-4">(</span><span class="mf">1.0</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">SA</span><span class="p" data-group-id="9268053806-4">)</span><span class="p">.</span></code></pre><p>The difference here is that a check is made for two keys in each map argument.
│ │ │ +The other keys are ignored.</p><p>Finally, let us return the resulting color in <code class="inline">blend/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">blend</span><span class="p" data-group-id="5355475504-1">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p">,</span><span class="n">Alpha</span><span class="p" data-group-id="5355475504-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Alpha</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mf">0.0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Dst</span><span class="p" data-group-id="5355475504-2">#{</span><span class="w">
│ │ │ +        </span><span class="ss">red</span><span class="w">   </span><span class="p">:=</span><span class="w"> </span><span class="nf">red</span><span class="p" data-group-id="5355475504-3">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="5355475504-3">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="ss">green</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="nf">green</span><span class="p" data-group-id="5355475504-4">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="5355475504-4">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="ss">blue</span><span class="w">  </span><span class="p">:=</span><span class="w"> </span><span class="nf">blue</span><span class="p" data-group-id="5355475504-5">(</span><span class="n">Src</span><span class="p">,</span><span class="n">Dst</span><span class="p" data-group-id="5355475504-5">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">Alpha</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="ss">alpha</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Alpha</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2937899339-2">}</span><span class="p">;</span></code></pre><p>The <code class="inline">Dst</code> map is updated with new channel values. The syntax for updating an
│ │ │ +    </span><span class="p" data-group-id="5355475504-2">}</span><span class="p">;</span></code></pre><p>The <code class="inline">Dst</code> map is updated with new channel values. The syntax for updating an
│ │ │  existing key with a new value is with the <code class="inline">:=</code> operator.</p><h2 id="standard-modules-and-manual-pages" class="section-heading">
│ │ │    <a href="#standard-modules-and-manual-pages" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Standard Modules and Manual Pages</span>
│ │ │  </h2>
│ │ │  <p>Erlang has many standard modules to help you do things. For example, the module
│ │ │ @@ -442,24 +442,24 @@
│ │ │    <a href="#writing-output-to-a-terminal" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Writing Output to a Terminal</span>
│ │ │  </h2>
│ │ │  <p>It is nice to be able to do formatted output in examples, so the next example
│ │ │  shows a simple way to use the <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function. Like all other exported
│ │ │ -functions, you can test the <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">31&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3026715181-1">(</span><span class="s">&quot;hello world</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3026715181-2">[</span><span class="p" data-group-id="3026715181-2">]</span><span class="p" data-group-id="3026715181-1">)</span><span class="p">.</span><span class="w">
│ │ │ +functions, you can test the <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">31&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5353190289-1">(</span><span class="s">&quot;hello world</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5353190289-2">[</span><span class="p" data-group-id="5353190289-2">]</span><span class="p" data-group-id="5353190289-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="w"> </span><span class="ss">world</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -32&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3026715181-3">(</span><span class="s">&quot;this outputs one Erlang term: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3026715181-4">[</span><span class="ss">hello</span><span class="p" data-group-id="3026715181-4">]</span><span class="p" data-group-id="3026715181-3">)</span><span class="p">.</span><span class="w">
│ │ │ +32&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5353190289-3">(</span><span class="s">&quot;this outputs one Erlang term: </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5353190289-4">[</span><span class="ss">hello</span><span class="p" data-group-id="5353190289-4">]</span><span class="p" data-group-id="5353190289-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">this</span><span class="w"> </span><span class="ss">outputs</span><span class="w"> </span><span class="ss">one</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="nc">term</span><span class="p">:</span><span class="w"> </span><span class="ss">hello</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -33&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3026715181-5">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3026715181-6">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="3026715181-6">]</span><span class="p" data-group-id="3026715181-5">)</span><span class="p">.</span><span class="w">
│ │ │ +33&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5353190289-5">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5353190289-6">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="5353190289-6">]</span><span class="p" data-group-id="5353190289-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">this</span><span class="w"> </span><span class="ss">outputs</span><span class="w"> </span><span class="ss">two</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="nc">terms</span><span class="p">:</span><span class="w"> </span><span class="ss">helloworld</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -34&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3026715181-7">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3026715181-8">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="3026715181-8">]</span><span class="p" data-group-id="3026715181-7">)</span><span class="p">.</span><span class="w">
│ │ │ +34&gt; </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5353190289-7">(</span><span class="s">&quot;this outputs two Erlang terms: </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5353190289-8">[</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">world</span><span class="p" data-group-id="5353190289-8">]</span><span class="p" data-group-id="5353190289-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">this</span><span class="w"> </span><span class="ss">outputs</span><span class="w"> </span><span class="ss">two</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="nc">terms</span><span class="p">:</span><span class="w"> </span><span class="ss">hello</span><span class="w"> </span><span class="ss">world</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>The function <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> (that is, <code class="inline">format</code> with two arguments) takes two lists.
│ │ │  The first one is nearly always a list written between <code class="inline">&quot; &quot;</code>. This list is printed
│ │ │  out as it is, except that each <code class="inline">~w</code> is replaced by a term taken in order from the
│ │ │  second list. Each ~n is replaced by a new line. The <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/2"><code class="inline">io:format/2</code></a> function
│ │ │  itself returns the atom <code class="inline">ok</code> if everything goes as planned. Like other functions
│ │ │  in Erlang, it crashes if an error occurs. This is not a fault in Erlang, it is a
│ │ │ @@ -473,34 +473,34 @@
│ │ │    <span class="text">A Larger Example</span>
│ │ │  </h2>
│ │ │  <p>Now for a larger example to consolidate what you have learnt so far. Assume that
│ │ │  you have a list of temperature readings from a number of cities in the world.
│ │ │  Some of them are in Celsius and some in Fahrenheit (as in the previous list).
│ │ │  First let us convert them all to Celsius, then let us print the data neatly.</p><pre><code class="makeup erlang" translate="no"><span class="c1">%% This module is in file tut5.erl</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9678167276-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="9678167276-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9678167276-2">(</span><span class="p" data-group-id="9678167276-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9678167276-3">]</span><span class="p" data-group-id="9678167276-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2221105578-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="2221105578-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2221105578-2">(</span><span class="p" data-group-id="2221105578-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2221105578-3">]</span><span class="p" data-group-id="2221105578-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% Only this function is exported</span><span class="w">
│ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="9678167276-4">(</span><span class="p" data-group-id="9678167276-5">[</span><span class="p" data-group-id="9678167276-5">]</span><span class="p" data-group-id="9678167276-4">)</span><span class="p">-&gt;</span><span class="w">                        </span><span class="c1">% No output for an empty list</span><span class="w">
│ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="2221105578-4">(</span><span class="p" data-group-id="2221105578-5">[</span><span class="p" data-group-id="2221105578-5">]</span><span class="p" data-group-id="2221105578-4">)</span><span class="p">-&gt;</span><span class="w">                        </span><span class="c1">% No output for an empty list</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="9678167276-6">(</span><span class="p" data-group-id="9678167276-7">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9678167276-7">]</span><span class="p" data-group-id="9678167276-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="9678167276-8">(</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="9678167276-9">(</span><span class="n">City</span><span class="p" data-group-id="9678167276-9">)</span><span class="p" data-group-id="9678167276-8">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">format_temps</span><span class="p" data-group-id="9678167276-10">(</span><span class="n">Rest</span><span class="p" data-group-id="9678167276-10">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="9678167276-11">(</span><span class="p" data-group-id="9678167276-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9678167276-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9678167276-13">}</span><span class="p" data-group-id="9678167276-12">}</span><span class="p" data-group-id="9678167276-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% No conversion needed</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9678167276-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9678167276-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9678167276-15">}</span><span class="p" data-group-id="9678167276-14">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="9678167276-16">(</span><span class="p" data-group-id="9678167276-17">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9678167276-18">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9678167276-18">}</span><span class="p" data-group-id="9678167276-17">}</span><span class="p" data-group-id="9678167276-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Do the conversion</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9678167276-19">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9678167276-20">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9678167276-21">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="9678167276-21">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="9678167276-20">}</span><span class="p" data-group-id="9678167276-19">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="9678167276-22">(</span><span class="p" data-group-id="9678167276-23">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9678167276-24">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9678167276-24">}</span><span class="p" data-group-id="9678167276-23">}</span><span class="p" data-group-id="9678167276-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9678167276-25">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9678167276-26">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9678167276-26">]</span><span class="p" data-group-id="9678167276-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">35&gt; </span><span class="nf">c</span><span class="p" data-group-id="8516746130-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="8516746130-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8516746130-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut5</span><span class="p" data-group-id="8516746130-2">}</span><span class="gp unselectable">
│ │ │ -36&gt; </span><span class="nc">tut5</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="8516746130-3">(</span><span class="p" data-group-id="8516746130-4">[</span><span class="p" data-group-id="8516746130-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="8516746130-6">}</span><span class="p" data-group-id="8516746130-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="8516746130-8">}</span><span class="p" data-group-id="8516746130-7">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8516746130-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="8516746130-10">}</span><span class="p" data-group-id="8516746130-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="8516746130-12">}</span><span class="p" data-group-id="8516746130-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8516746130-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="8516746130-14">}</span><span class="p" data-group-id="8516746130-13">}</span><span class="p" data-group-id="8516746130-4">]</span><span class="p" data-group-id="8516746130-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="2221105578-6">(</span><span class="p" data-group-id="2221105578-7">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="2221105578-7">]</span><span class="p" data-group-id="2221105578-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="2221105578-8">(</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="2221105578-9">(</span><span class="n">City</span><span class="p" data-group-id="2221105578-9">)</span><span class="p" data-group-id="2221105578-8">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">format_temps</span><span class="p" data-group-id="2221105578-10">(</span><span class="n">Rest</span><span class="p" data-group-id="2221105578-10">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="2221105578-11">(</span><span class="p" data-group-id="2221105578-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2221105578-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2221105578-13">}</span><span class="p" data-group-id="2221105578-12">}</span><span class="p" data-group-id="2221105578-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% No conversion needed</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2221105578-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2221105578-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2221105578-15">}</span><span class="p" data-group-id="2221105578-14">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">convert_to_celsius</span><span class="p" data-group-id="2221105578-16">(</span><span class="p" data-group-id="2221105578-17">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2221105578-18">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2221105578-18">}</span><span class="p" data-group-id="2221105578-17">}</span><span class="p" data-group-id="2221105578-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">  </span><span class="c1">% Do the conversion</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2221105578-19">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2221105578-20">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2221105578-21">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="2221105578-21">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="2221105578-20">}</span><span class="p" data-group-id="2221105578-19">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="2221105578-22">(</span><span class="p" data-group-id="2221105578-23">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2221105578-24">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2221105578-24">}</span><span class="p" data-group-id="2221105578-23">}</span><span class="p" data-group-id="2221105578-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2221105578-25">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2221105578-26">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2221105578-26">]</span><span class="p" data-group-id="2221105578-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">35&gt; </span><span class="nf">c</span><span class="p" data-group-id="7891337020-1">(</span><span class="ss">tut5</span><span class="p" data-group-id="7891337020-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7891337020-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut5</span><span class="p" data-group-id="7891337020-2">}</span><span class="gp unselectable">
│ │ │ +36&gt; </span><span class="nc">tut5</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="7891337020-3">(</span><span class="p" data-group-id="7891337020-4">[</span><span class="p" data-group-id="7891337020-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="7891337020-6">}</span><span class="p" data-group-id="7891337020-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="7891337020-8">}</span><span class="p" data-group-id="7891337020-7">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7891337020-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="7891337020-10">}</span><span class="p" data-group-id="7891337020-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="7891337020-12">}</span><span class="p" data-group-id="7891337020-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7891337020-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="7891337020-14">}</span><span class="p" data-group-id="7891337020-13">}</span><span class="p" data-group-id="7891337020-4">]</span><span class="p" data-group-id="7891337020-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="o">-</span><span class="mi">4</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>Before looking at how this program works, notice that a few comments are added
│ │ │  to the code. A comment starts with a %-character and goes on to the end of the
│ │ │ @@ -528,28 +528,28 @@
│ │ │    <a href="#matching-guards-and-scope-of-variables" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Matching, Guards, and Scope of Variables</span>
│ │ │  </h2>
│ │ │  <p>It can be useful to find the maximum and minimum temperature in lists like this.
│ │ │  Before extending the program to do this, let us look at functions for finding
│ │ │ -the maximum value of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2994111439-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="2994111439-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2994111439-2">(</span><span class="p" data-group-id="2994111439-3">[</span><span class="ss">list_max</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2994111439-3">]</span><span class="p" data-group-id="2994111439-2">)</span><span class="p">.</span><span class="w">
│ │ │ +the maximum value of the elements in a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1885755746-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="1885755746-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1885755746-2">(</span><span class="p" data-group-id="1885755746-3">[</span><span class="ss">list_max</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1885755746-3">]</span><span class="p" data-group-id="1885755746-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="2994111439-4">(</span><span class="p" data-group-id="2994111439-5">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="2994111439-5">]</span><span class="p" data-group-id="2994111439-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -   </span><span class="nf">list_max</span><span class="p" data-group-id="2994111439-6">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="2994111439-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="1885755746-4">(</span><span class="p" data-group-id="1885755746-5">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="1885755746-5">]</span><span class="p" data-group-id="1885755746-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +   </span><span class="nf">list_max</span><span class="p" data-group-id="1885755746-6">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="1885755746-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="2994111439-7">(</span><span class="p" data-group-id="2994111439-8">[</span><span class="p" data-group-id="2994111439-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="2994111439-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="1885755746-7">(</span><span class="p" data-group-id="1885755746-8">[</span><span class="p" data-group-id="1885755746-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="1885755746-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Res</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="2994111439-9">(</span><span class="p" data-group-id="2994111439-10">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="2994111439-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="2994111439-9">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">list_max</span><span class="p" data-group-id="2994111439-11">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="2994111439-11">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">list_max</span><span class="p" data-group-id="2994111439-12">(</span><span class="p" data-group-id="2994111439-13">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="2994111439-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="2994111439-12">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">list_max</span><span class="p" data-group-id="2994111439-14">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="2994111439-14">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">37&gt; </span><span class="nf">c</span><span class="p" data-group-id="9647302036-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="9647302036-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9647302036-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut6</span><span class="p" data-group-id="9647302036-2">}</span><span class="gp unselectable">
│ │ │ -38&gt; </span><span class="nc">tut6</span><span class="p">:</span><span class="nf">list_max</span><span class="p" data-group-id="9647302036-3">(</span><span class="p" data-group-id="9647302036-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9647302036-4">]</span><span class="p" data-group-id="9647302036-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="1885755746-9">(</span><span class="p" data-group-id="1885755746-10">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="1885755746-10">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="1885755746-9">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">list_max</span><span class="p" data-group-id="1885755746-11">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Head</span><span class="p" data-group-id="1885755746-11">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">list_max</span><span class="p" data-group-id="1885755746-12">(</span><span class="p" data-group-id="1885755746-13">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="1885755746-13">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="1885755746-12">)</span><span class="w">  </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">list_max</span><span class="p" data-group-id="1885755746-14">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="1885755746-14">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">37&gt; </span><span class="nf">c</span><span class="p" data-group-id="1813470827-1">(</span><span class="ss">tut6</span><span class="p" data-group-id="1813470827-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1813470827-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut6</span><span class="p" data-group-id="1813470827-2">}</span><span class="gp unselectable">
│ │ │ +38&gt; </span><span class="nc">tut6</span><span class="p">:</span><span class="nf">list_max</span><span class="p" data-group-id="1813470827-3">(</span><span class="p" data-group-id="1813470827-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="1813470827-4">]</span><span class="p" data-group-id="1813470827-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">7</span></code></pre><p>First notice that two functions have the same name, <code class="inline">list_max</code>. However, each of
│ │ │  these takes a different number of arguments (parameters). In Erlang these are
│ │ │  regarded as completely different functions. Where you need to distinguish
│ │ │  between these functions, you write Name/Arity, where Name is the function name
│ │ │  and Arity is the number of arguments, in this case <code class="inline">list_max/1</code> and
│ │ │  <code class="inline">list_max/2</code>.</p><p>In this example you walk through a list &quot;carrying&quot; a value, in this case
│ │ │  <code class="inline">Result_so_far</code>. <code class="inline">list_max/1</code> simply assumes that the max value of the list is
│ │ │ @@ -578,180 +578,180 @@
│ │ │  </span><span class="mi">5</span><span class="gp unselectable">
│ │ │  40&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">6</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no match of right hand side value 6</span><span class="gp unselectable">
│ │ │  41&gt; </span><span class="n">M</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no match of right hand side value 6</span><span class="gp unselectable">
│ │ │  42&gt; </span><span class="n">N</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">6</span></code></pre><p>The use of the match operator is particularly useful for pulling apart Erlang
│ │ │ -terms and creating new ones.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">43&gt; </span><span class="p" data-group-id="9371009274-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9371009274-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9371009274-2">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9371009274-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="9371009274-3">}</span><span class="p" data-group-id="9371009274-2">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9371009274-4">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="9371009274-5">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="9371009274-5">}</span><span class="p" data-group-id="9371009274-4">}</span><span class="gp unselectable">
│ │ │ +terms and creating new ones.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">43&gt; </span><span class="p" data-group-id="8594584670-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="8594584670-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8594584670-2">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8594584670-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="8594584670-3">}</span><span class="p" data-group-id="8594584670-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8594584670-4">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="8594584670-5">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="8594584670-5">}</span><span class="p" data-group-id="8594584670-4">}</span><span class="gp unselectable">
│ │ │  44&gt; </span><span class="n">X</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">paris</span><span class="gp unselectable">
│ │ │  45&gt; </span><span class="n">Y</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9371009274-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="9371009274-6">}</span></code></pre><p>Here <code class="inline">X</code> gets the value <code class="inline">paris</code> and <code class="inline">Y</code> the value <code class="inline">{f,28}</code>.</p><p>If you try to do the same again with another city, an error is returned:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">46&gt; </span><span class="p" data-group-id="1182260080-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1182260080-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1182260080-2">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1182260080-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="1182260080-3">}</span><span class="p" data-group-id="1182260080-2">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8594584670-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">28</span><span class="p" data-group-id="8594584670-6">}</span></code></pre><p>Here <code class="inline">X</code> gets the value <code class="inline">paris</code> and <code class="inline">Y</code> the value <code class="inline">{f,28}</code>.</p><p>If you try to do the same again with another city, an error is returned:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">46&gt; </span><span class="p" data-group-id="4665157126-1">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="4665157126-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4665157126-2">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4665157126-3">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="4665157126-3">}</span><span class="p" data-group-id="4665157126-2">}</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no match of right hand side value {london,{f,36}}</span></code></pre><p>Variables can also be used to improve the readability of programs. For example,
│ │ │ -in function <code class="inline">list_max/2</code> above, you can write:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_max</span><span class="p" data-group-id="2087827926-1">(</span><span class="p" data-group-id="2087827926-2">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="2087827926-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="2087827926-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +in function <code class="inline">list_max/2</code> above, you can write:</p><pre><code class="makeup erlang" translate="no"><span class="nf">list_max</span><span class="p" data-group-id="8935388466-1">(</span><span class="p" data-group-id="8935388466-2">[</span><span class="n">Head</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="8935388466-2">]</span><span class="p">,</span><span class="w"> </span><span class="n">Result_so_far</span><span class="p" data-group-id="8935388466-1">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Head</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Result_so_far</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">New_result_far</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Head</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">list_max</span><span class="p" data-group-id="2087827926-3">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">New_result_far</span><span class="p" data-group-id="2087827926-3">)</span><span class="p">;</span></code></pre><p>This is possibly a little clearer.</p><h2 id="more-about-lists" class="section-heading">
│ │ │ +    </span><span class="nf">list_max</span><span class="p" data-group-id="8935388466-3">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">New_result_far</span><span class="p" data-group-id="8935388466-3">)</span><span class="p">;</span></code></pre><p>This is possibly a little clearer.</p><h2 id="more-about-lists" class="section-heading">
│ │ │    <a href="#more-about-lists" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">More About Lists</span>
│ │ │  </h2>
│ │ │ -<p>Remember that the <code class="inline">|</code> operator can be used to get the head of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">47&gt; </span><span class="p" data-group-id="0140899190-1">[</span><span class="n">M1</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="0140899190-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0140899190-2">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="ss">rome</span><span class="p" data-group-id="0140899190-2">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0140899190-3">[</span><span class="ss">paris</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="0140899190-3">]</span><span class="gp unselectable">
│ │ │ +<p>Remember that the <code class="inline">|</code> operator can be used to get the head of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">47&gt; </span><span class="p" data-group-id="6284078119-1">[</span><span class="n">M1</span><span class="p">|</span><span class="n">T1</span><span class="p" data-group-id="6284078119-1">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6284078119-2">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="ss">rome</span><span class="p" data-group-id="6284078119-2">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6284078119-3">[</span><span class="ss">paris</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="6284078119-3">]</span><span class="gp unselectable">
│ │ │  48&gt; </span><span class="n">M1</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">paris</span><span class="gp unselectable">
│ │ │  49&gt; </span><span class="n">T1</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0140899190-4">[</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="0140899190-4">]</span></code></pre><p>The <code class="inline">|</code> operator can also be used to add a head to a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">50&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6238057431-1">[</span><span class="ss">madrid</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="6238057431-1">]</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6238057431-2">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="6238057431-2">]</span><span class="gp unselectable">
│ │ │ +</span><span class="p" data-group-id="6284078119-4">[</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="6284078119-4">]</span></code></pre><p>The <code class="inline">|</code> operator can also be used to add a head to a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">50&gt; </span><span class="n">L1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2010153855-1">[</span><span class="ss">madrid</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2010153855-1">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2010153855-2">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="2010153855-2">]</span><span class="gp unselectable">
│ │ │  51&gt; </span><span class="n">L1</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6238057431-3">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="6238057431-3">]</span></code></pre><p>Now an example of this when working with lists - reversing the order of a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0163086026-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="0163086026-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2010153855-3">[</span><span class="ss">madrid</span><span class="p">,</span><span class="ss">london</span><span class="p">,</span><span class="ss">rome</span><span class="p" data-group-id="2010153855-3">]</span></code></pre><p>Now an example of this when working with lists - reversing the order of a list:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8602441235-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="8602441235-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0163086026-2">(</span><span class="p" data-group-id="0163086026-3">[</span><span class="ss">reverse</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0163086026-3">]</span><span class="p" data-group-id="0163086026-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8602441235-2">(</span><span class="p" data-group-id="8602441235-3">[</span><span class="ss">reverse</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8602441235-3">]</span><span class="p" data-group-id="8602441235-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="0163086026-4">(</span><span class="n">List</span><span class="p" data-group-id="0163086026-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="0163086026-5">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0163086026-6">[</span><span class="p" data-group-id="0163086026-6">]</span><span class="p" data-group-id="0163086026-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="8602441235-4">(</span><span class="n">List</span><span class="p" data-group-id="8602441235-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="8602441235-5">(</span><span class="n">List</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8602441235-6">[</span><span class="p" data-group-id="8602441235-6">]</span><span class="p" data-group-id="8602441235-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="0163086026-7">(</span><span class="p" data-group-id="0163086026-8">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="0163086026-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="0163086026-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="0163086026-9">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0163086026-10">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="0163086026-10">]</span><span class="p" data-group-id="0163086026-9">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="0163086026-11">(</span><span class="p" data-group-id="0163086026-12">[</span><span class="p" data-group-id="0163086026-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="0163086026-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Reversed_List</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">52&gt; </span><span class="nf">c</span><span class="p" data-group-id="9102790767-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="9102790767-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9102790767-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut8</span><span class="p" data-group-id="9102790767-2">}</span><span class="gp unselectable">
│ │ │ -53&gt; </span><span class="nc">tut8</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="9102790767-3">(</span><span class="p" data-group-id="9102790767-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9102790767-4">]</span><span class="p" data-group-id="9102790767-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9102790767-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9102790767-5">]</span></code></pre><p>Consider how <code class="inline">Reversed_List</code> is built. It starts as [], then successively the
│ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="8602441235-7">(</span><span class="p" data-group-id="8602441235-8">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8602441235-8">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="8602441235-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="8602441235-9">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8602441235-10">[</span><span class="n">Head</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="8602441235-10">]</span><span class="p" data-group-id="8602441235-9">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="8602441235-11">(</span><span class="p" data-group-id="8602441235-12">[</span><span class="p" data-group-id="8602441235-12">]</span><span class="p">,</span><span class="w"> </span><span class="n">Reversed_List</span><span class="p" data-group-id="8602441235-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Reversed_List</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">52&gt; </span><span class="nf">c</span><span class="p" data-group-id="0193031535-1">(</span><span class="ss">tut8</span><span class="p" data-group-id="0193031535-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0193031535-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut8</span><span class="p" data-group-id="0193031535-2">}</span><span class="gp unselectable">
│ │ │ +53&gt; </span><span class="nc">tut8</span><span class="p">:</span><span class="nf">reverse</span><span class="p" data-group-id="0193031535-3">(</span><span class="p" data-group-id="0193031535-4">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0193031535-4">]</span><span class="p" data-group-id="0193031535-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0193031535-5">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0193031535-5">]</span></code></pre><p>Consider how <code class="inline">Reversed_List</code> is built. It starts as [], then successively the
│ │ │  heads are taken off of the list to be reversed and added to the the
│ │ │ -<code class="inline">Reversed_List</code>, as shown in the following:</p><pre><code class="makeup erlang" translate="no"><span class="nf">reverse</span><span class="p" data-group-id="9779580692-1">(</span><span class="p" data-group-id="9779580692-2">[</span><span class="mi">1</span><span class="p">|</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9779580692-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779580692-3">[</span><span class="p" data-group-id="9779580692-3">]</span><span class="p" data-group-id="9779580692-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="9779580692-4">(</span><span class="p" data-group-id="9779580692-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9779580692-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779580692-6">[</span><span class="mi">1</span><span class="p">|</span><span class="p" data-group-id="9779580692-7">[</span><span class="p" data-group-id="9779580692-7">]</span><span class="p" data-group-id="9779580692-6">]</span><span class="p" data-group-id="9779580692-4">)</span><span class="w">
│ │ │ +<code class="inline">Reversed_List</code>, as shown in the following:</p><pre><code class="makeup erlang" translate="no"><span class="nf">reverse</span><span class="p" data-group-id="8588877125-1">(</span><span class="p" data-group-id="8588877125-2">[</span><span class="mi">1</span><span class="p">|</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8588877125-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8588877125-3">[</span><span class="p" data-group-id="8588877125-3">]</span><span class="p" data-group-id="8588877125-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="8588877125-4">(</span><span class="p" data-group-id="8588877125-5">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8588877125-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8588877125-6">[</span><span class="mi">1</span><span class="p">|</span><span class="p" data-group-id="8588877125-7">[</span><span class="p" data-group-id="8588877125-7">]</span><span class="p" data-group-id="8588877125-6">]</span><span class="p" data-group-id="8588877125-4">)</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="9779580692-8">(</span><span class="p" data-group-id="9779580692-9">[</span><span class="mi">2</span><span class="p">|</span><span class="mi">3</span><span class="p" data-group-id="9779580692-9">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779580692-10">[</span><span class="mi">1</span><span class="p" data-group-id="9779580692-10">]</span><span class="p" data-group-id="9779580692-8">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="9779580692-11">(</span><span class="p" data-group-id="9779580692-12">[</span><span class="mi">3</span><span class="p" data-group-id="9779580692-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779580692-13">[</span><span class="mi">2</span><span class="p">|</span><span class="p" data-group-id="9779580692-14">[</span><span class="mi">1</span><span class="p" data-group-id="9779580692-14">]</span><span class="p">)</span><span class="w">
│ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="8588877125-8">(</span><span class="p" data-group-id="8588877125-9">[</span><span class="mi">2</span><span class="p">|</span><span class="mi">3</span><span class="p" data-group-id="8588877125-9">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8588877125-10">[</span><span class="mi">1</span><span class="p" data-group-id="8588877125-10">]</span><span class="p" data-group-id="8588877125-8">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="8588877125-11">(</span><span class="p" data-group-id="8588877125-12">[</span><span class="mi">3</span><span class="p" data-group-id="8588877125-12">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8588877125-13">[</span><span class="mi">2</span><span class="p">|</span><span class="p" data-group-id="8588877125-14">[</span><span class="mi">1</span><span class="p" data-group-id="8588877125-14">]</span><span class="p">)</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="9779580692-15">(</span><span class="p" data-group-id="9779580692-16">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="9779580692-17">[</span><span class="p" data-group-id="9779580692-17">]</span><span class="p" data-group-id="9779580692-16">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779580692-18">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9779580692-18">]</span><span class="p" data-group-id="9779580692-15">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">reverse</span><span class="p" data-group-id="9779580692-19">(</span><span class="p" data-group-id="9779580692-20">[</span><span class="p" data-group-id="9779580692-20">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779580692-21">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="9779580692-22">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9779580692-22">]</span><span class="p" data-group-id="9779580692-21">]</span><span class="p" data-group-id="9779580692-19">)</span><span class="w">
│ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="8588877125-15">(</span><span class="p" data-group-id="8588877125-16">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="8588877125-17">[</span><span class="p" data-group-id="8588877125-17">]</span><span class="p" data-group-id="8588877125-16">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8588877125-18">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8588877125-18">]</span><span class="p" data-group-id="8588877125-15">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">reverse</span><span class="p" data-group-id="8588877125-19">(</span><span class="p" data-group-id="8588877125-20">[</span><span class="p" data-group-id="8588877125-20">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8588877125-21">[</span><span class="mi">3</span><span class="p">|</span><span class="p" data-group-id="8588877125-22">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8588877125-22">]</span><span class="p" data-group-id="8588877125-21">]</span><span class="p" data-group-id="8588877125-19">)</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">reverse</span><span class="p" data-group-id="9779580692-23">(</span><span class="p" data-group-id="9779580692-24">[</span><span class="p" data-group-id="9779580692-24">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9779580692-25">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9779580692-25">]</span><span class="p" data-group-id="9779580692-23">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9779580692-26">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="9779580692-26">]</span></code></pre><p>The module <code class="inline">lists</code> contains many functions for manipulating lists, for example,
│ │ │ +</span><span class="nf">reverse</span><span class="p" data-group-id="8588877125-23">(</span><span class="p" data-group-id="8588877125-24">[</span><span class="p" data-group-id="8588877125-24">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8588877125-25">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8588877125-25">]</span><span class="p" data-group-id="8588877125-23">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8588877125-26">[</span><span class="mi">3</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8588877125-26">]</span></code></pre><p>The module <code class="inline">lists</code> contains many functions for manipulating lists, for example,
│ │ │  for reversing them. So before writing a list-manipulating function it is a good
│ │ │  idea to check if one not already is written for you (see the <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html"><code class="inline">lists</code></a> manual
│ │ │  page in STDLIB).</p><p>Now let us get back to the cities and temperatures, but take a more structured
│ │ │ -approach this time. First let us convert the whole list to Celsius as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9407608120-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="9407608120-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9407608120-2">(</span><span class="p" data-group-id="9407608120-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9407608120-3">]</span><span class="p" data-group-id="9407608120-2">)</span><span class="p">.</span><span class="w">
│ │ │ +approach this time. First let us convert the whole list to Celsius as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3685566346-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="3685566346-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3685566346-2">(</span><span class="p" data-group-id="3685566346-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3685566346-3">]</span><span class="p" data-group-id="3685566346-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="9407608120-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="9407608120-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9407608120-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="9407608120-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="3685566346-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="3685566346-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3685566346-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="3685566346-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9407608120-6">(</span><span class="p" data-group-id="9407608120-7">[</span><span class="p" data-group-id="9407608120-8">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9407608120-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="9407608120-9">}</span><span class="p" data-group-id="9407608120-8">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9407608120-7">]</span><span class="p" data-group-id="9407608120-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9407608120-10">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9407608120-11">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9407608120-12">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="9407608120-12">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="9407608120-11">}</span><span class="p" data-group-id="9407608120-10">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9407608120-13">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9407608120-14">(</span><span class="n">Rest</span><span class="p" data-group-id="9407608120-14">)</span><span class="p" data-group-id="9407608120-13">]</span><span class="p">;</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9407608120-15">(</span><span class="p" data-group-id="9407608120-16">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9407608120-16">]</span><span class="p" data-group-id="9407608120-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9407608120-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9407608120-18">(</span><span class="n">Rest</span><span class="p" data-group-id="9407608120-18">)</span><span class="p" data-group-id="9407608120-17">]</span><span class="p">;</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9407608120-19">(</span><span class="p" data-group-id="9407608120-20">[</span><span class="p" data-group-id="9407608120-20">]</span><span class="p" data-group-id="9407608120-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9407608120-21">[</span><span class="p" data-group-id="9407608120-21">]</span><span class="p">.</span></code></pre><p>Test the function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">54&gt; </span><span class="nf">c</span><span class="p" data-group-id="1774962856-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="1774962856-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1774962856-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="1774962856-2">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ -55&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="1774962856-3">(</span><span class="p" data-group-id="1774962856-4">[</span><span class="p" data-group-id="1774962856-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="1774962856-6">}</span><span class="p" data-group-id="1774962856-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="1774962856-8">}</span><span class="p" data-group-id="1774962856-7">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1774962856-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="1774962856-10">}</span><span class="p" data-group-id="1774962856-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="1774962856-12">}</span><span class="p" data-group-id="1774962856-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1774962856-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="1774962856-14">}</span><span class="p" data-group-id="1774962856-13">}</span><span class="p" data-group-id="1774962856-4">]</span><span class="p" data-group-id="1774962856-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1774962856-15">[</span><span class="p" data-group-id="1774962856-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="1774962856-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="1774962856-17">}</span><span class="p" data-group-id="1774962856-16">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1774962856-18">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="1774962856-19">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">21.11111111111111</span><span class="p" data-group-id="1774962856-19">}</span><span class="p" data-group-id="1774962856-18">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1774962856-20">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="1774962856-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="1774962856-21">}</span><span class="p" data-group-id="1774962856-20">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1774962856-22">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="1774962856-23">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="1774962856-23">}</span><span class="p" data-group-id="1774962856-22">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1774962856-24">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="1774962856-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="1774962856-25">}</span><span class="p" data-group-id="1774962856-24">}</span><span class="p" data-group-id="1774962856-15">]</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">format_temps</span><span class="p" data-group-id="8826023670-1">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8826023670-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8826023670-2">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8826023670-2">)</span><span class="p">.</span></code></pre><p>Here <code class="inline">format_temps/1</code> calls <code class="inline">convert_list_to_c/1</code>. <code class="inline">convert_list_to_c/1</code> takes
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3685566346-6">(</span><span class="p" data-group-id="3685566346-7">[</span><span class="p" data-group-id="3685566346-8">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3685566346-9">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="3685566346-9">}</span><span class="p" data-group-id="3685566346-8">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="3685566346-7">]</span><span class="p" data-group-id="3685566346-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3685566346-10">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3685566346-11">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3685566346-12">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="3685566346-12">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="3685566346-11">}</span><span class="p" data-group-id="3685566346-10">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3685566346-13">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3685566346-14">(</span><span class="n">Rest</span><span class="p" data-group-id="3685566346-14">)</span><span class="p" data-group-id="3685566346-13">]</span><span class="p">;</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3685566346-15">(</span><span class="p" data-group-id="3685566346-16">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="3685566346-16">]</span><span class="p" data-group-id="3685566346-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3685566346-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3685566346-18">(</span><span class="n">Rest</span><span class="p" data-group-id="3685566346-18">)</span><span class="p" data-group-id="3685566346-17">]</span><span class="p">;</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3685566346-19">(</span><span class="p" data-group-id="3685566346-20">[</span><span class="p" data-group-id="3685566346-20">]</span><span class="p" data-group-id="3685566346-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3685566346-21">[</span><span class="p" data-group-id="3685566346-21">]</span><span class="p">.</span></code></pre><p>Test the function:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">54&gt; </span><span class="nf">c</span><span class="p" data-group-id="5385732206-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="5385732206-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5385732206-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="5385732206-2">}</span><span class="p">.</span><span class="gp unselectable">
│ │ │ +55&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="5385732206-3">(</span><span class="p" data-group-id="5385732206-4">[</span><span class="p" data-group-id="5385732206-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="5385732206-6">}</span><span class="p" data-group-id="5385732206-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="5385732206-8">}</span><span class="p" data-group-id="5385732206-7">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5385732206-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="5385732206-10">}</span><span class="p" data-group-id="5385732206-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="5385732206-12">}</span><span class="p" data-group-id="5385732206-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5385732206-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="5385732206-14">}</span><span class="p" data-group-id="5385732206-13">}</span><span class="p" data-group-id="5385732206-4">]</span><span class="p" data-group-id="5385732206-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5385732206-15">[</span><span class="p" data-group-id="5385732206-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="5385732206-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="5385732206-17">}</span><span class="p" data-group-id="5385732206-16">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5385732206-18">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="5385732206-19">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">21.11111111111111</span><span class="p" data-group-id="5385732206-19">}</span><span class="p" data-group-id="5385732206-18">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5385732206-20">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="5385732206-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="5385732206-21">}</span><span class="p" data-group-id="5385732206-20">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5385732206-22">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="5385732206-23">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="5385732206-23">}</span><span class="p" data-group-id="5385732206-22">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5385732206-24">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="5385732206-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mf">2.2222222222222223</span><span class="p" data-group-id="5385732206-25">}</span><span class="p" data-group-id="5385732206-24">}</span><span class="p" data-group-id="5385732206-15">]</span></code></pre><p>Explanation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">format_temps</span><span class="p" data-group-id="8378020651-1">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8378020651-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8378020651-2">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8378020651-2">)</span><span class="p">.</span></code></pre><p>Here <code class="inline">format_temps/1</code> calls <code class="inline">convert_list_to_c/1</code>. <code class="inline">convert_list_to_c/1</code> takes
│ │ │  off the head of the <code class="inline">List_of_cities</code>, converts it to Celsius if needed. The <code class="inline">|</code>
│ │ │ -operator is used to add the (maybe) converted to the converted rest of the list:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9757922445-1">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9757922445-2">(</span><span class="n">Rest</span><span class="p" data-group-id="9757922445-2">)</span><span class="p" data-group-id="9757922445-1">]</span><span class="p">;</span></code></pre><p>or:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9866263585-1">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9866263585-2">(</span><span class="n">Rest</span><span class="p" data-group-id="9866263585-2">)</span><span class="p" data-group-id="9866263585-1">]</span><span class="p">;</span></code></pre><p>This is done until the end of the list is reached, that is, the list is empty:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_list_to_c</span><span class="p" data-group-id="7054440962-1">(</span><span class="p" data-group-id="7054440962-2">[</span><span class="p" data-group-id="7054440962-2">]</span><span class="p" data-group-id="7054440962-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7054440962-3">[</span><span class="p" data-group-id="7054440962-3">]</span><span class="p">.</span></code></pre><p>Now when the list is converted, a function to print it is added:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8819508372-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="8819508372-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8819508372-2">(</span><span class="p" data-group-id="8819508372-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8819508372-3">]</span><span class="p" data-group-id="8819508372-2">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="8819508372-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8819508372-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8819508372-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8819508372-5">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="8819508372-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="8819508372-6">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8819508372-7">(</span><span class="p" data-group-id="8819508372-8">[</span><span class="p" data-group-id="8819508372-9">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8819508372-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="8819508372-10">}</span><span class="p" data-group-id="8819508372-9">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8819508372-8">]</span><span class="p" data-group-id="8819508372-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8819508372-11">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8819508372-12">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8819508372-13">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="8819508372-13">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="8819508372-12">}</span><span class="p" data-group-id="8819508372-11">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8819508372-14">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8819508372-15">(</span><span class="n">Rest</span><span class="p" data-group-id="8819508372-15">)</span><span class="p" data-group-id="8819508372-14">]</span><span class="p">;</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8819508372-16">(</span><span class="p" data-group-id="8819508372-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8819508372-17">]</span><span class="p" data-group-id="8819508372-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8819508372-18">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8819508372-19">(</span><span class="n">Rest</span><span class="p" data-group-id="8819508372-19">)</span><span class="p" data-group-id="8819508372-18">]</span><span class="p">;</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8819508372-20">(</span><span class="p" data-group-id="8819508372-21">[</span><span class="p" data-group-id="8819508372-21">]</span><span class="p" data-group-id="8819508372-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8819508372-22">[</span><span class="p" data-group-id="8819508372-22">]</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="8819508372-23">(</span><span class="p" data-group-id="8819508372-24">[</span><span class="p" data-group-id="8819508372-25">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8819508372-26">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8819508372-26">}</span><span class="p" data-group-id="8819508372-25">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8819508372-24">]</span><span class="p" data-group-id="8819508372-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8819508372-27">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8819508372-28">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8819508372-28">]</span><span class="p" data-group-id="8819508372-27">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="8819508372-29">(</span><span class="n">Rest</span><span class="p" data-group-id="8819508372-29">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="8819508372-30">(</span><span class="p" data-group-id="8819508372-31">[</span><span class="p" data-group-id="8819508372-31">]</span><span class="p" data-group-id="8819508372-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ok</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">56&gt; </span><span class="nf">c</span><span class="p" data-group-id="6838843510-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="6838843510-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6838843510-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut7</span><span class="p" data-group-id="6838843510-2">}</span><span class="gp unselectable">
│ │ │ -57&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="6838843510-3">(</span><span class="p" data-group-id="6838843510-4">[</span><span class="p" data-group-id="6838843510-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="6838843510-6">}</span><span class="p" data-group-id="6838843510-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="6838843510-8">}</span><span class="p" data-group-id="6838843510-7">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6838843510-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="6838843510-10">}</span><span class="p" data-group-id="6838843510-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="6838843510-12">}</span><span class="p" data-group-id="6838843510-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6838843510-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="6838843510-14">}</span><span class="p" data-group-id="6838843510-13">}</span><span class="p" data-group-id="6838843510-4">]</span><span class="p" data-group-id="6838843510-3">)</span><span class="p">.</span><span class="w">
│ │ │ +operator is used to add the (maybe) converted to the converted rest of the list:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2974054361-1">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2974054361-2">(</span><span class="n">Rest</span><span class="p" data-group-id="2974054361-2">)</span><span class="p" data-group-id="2974054361-1">]</span><span class="p">;</span></code></pre><p>or:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0186412353-1">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="0186412353-2">(</span><span class="n">Rest</span><span class="p" data-group-id="0186412353-2">)</span><span class="p" data-group-id="0186412353-1">]</span><span class="p">;</span></code></pre><p>This is done until the end of the list is reached, that is, the list is empty:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_list_to_c</span><span class="p" data-group-id="4637807503-1">(</span><span class="p" data-group-id="4637807503-2">[</span><span class="p" data-group-id="4637807503-2">]</span><span class="p" data-group-id="4637807503-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4637807503-3">[</span><span class="p" data-group-id="4637807503-3">]</span><span class="p">.</span></code></pre><p>Now when the list is converted, a function to print it is added:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3152680789-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="3152680789-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3152680789-2">(</span><span class="p" data-group-id="3152680789-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3152680789-3">]</span><span class="p" data-group-id="3152680789-2">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="3152680789-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="3152680789-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3152680789-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="3152680789-5">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="3152680789-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="3152680789-6">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3152680789-7">(</span><span class="p" data-group-id="3152680789-8">[</span><span class="p" data-group-id="3152680789-9">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3152680789-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="3152680789-10">}</span><span class="p" data-group-id="3152680789-9">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="3152680789-8">]</span><span class="p" data-group-id="3152680789-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3152680789-11">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3152680789-12">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3152680789-13">(</span><span class="n">F</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="3152680789-13">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="3152680789-12">}</span><span class="p" data-group-id="3152680789-11">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3152680789-14">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3152680789-15">(</span><span class="n">Rest</span><span class="p" data-group-id="3152680789-15">)</span><span class="p" data-group-id="3152680789-14">]</span><span class="p">;</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3152680789-16">(</span><span class="p" data-group-id="3152680789-17">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="3152680789-17">]</span><span class="p" data-group-id="3152680789-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3152680789-18">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3152680789-19">(</span><span class="n">Rest</span><span class="p" data-group-id="3152680789-19">)</span><span class="p" data-group-id="3152680789-18">]</span><span class="p">;</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3152680789-20">(</span><span class="p" data-group-id="3152680789-21">[</span><span class="p" data-group-id="3152680789-21">]</span><span class="p" data-group-id="3152680789-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3152680789-22">[</span><span class="p" data-group-id="3152680789-22">]</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="3152680789-23">(</span><span class="p" data-group-id="3152680789-24">[</span><span class="p" data-group-id="3152680789-25">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3152680789-26">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="3152680789-26">}</span><span class="p" data-group-id="3152680789-25">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="3152680789-24">]</span><span class="p" data-group-id="3152680789-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3152680789-27">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3152680789-28">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="3152680789-28">]</span><span class="p" data-group-id="3152680789-27">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="3152680789-29">(</span><span class="n">Rest</span><span class="p" data-group-id="3152680789-29">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="3152680789-30">(</span><span class="p" data-group-id="3152680789-31">[</span><span class="p" data-group-id="3152680789-31">]</span><span class="p" data-group-id="3152680789-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ok</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">56&gt; </span><span class="nf">c</span><span class="p" data-group-id="8429269876-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="8429269876-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8429269876-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut7</span><span class="p" data-group-id="8429269876-2">}</span><span class="gp unselectable">
│ │ │ +57&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="8429269876-3">(</span><span class="p" data-group-id="8429269876-4">[</span><span class="p" data-group-id="8429269876-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="8429269876-6">}</span><span class="p" data-group-id="8429269876-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="8429269876-8">}</span><span class="p" data-group-id="8429269876-7">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8429269876-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="8429269876-10">}</span><span class="p" data-group-id="8429269876-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="8429269876-12">}</span><span class="p" data-group-id="8429269876-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8429269876-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="8429269876-14">}</span><span class="p" data-group-id="8429269876-13">}</span><span class="p" data-group-id="8429269876-4">]</span><span class="p" data-group-id="8429269876-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="o">-</span><span class="mi">4</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>Now a function has to be added to find the cities with the maximum and minimum
│ │ │  temperatures. The following program is not the most efficient way of doing this
│ │ │  as you walk through the list of cities four times. But it is better to first
│ │ │  strive for clarity and correctness and to make programs efficient only if
│ │ │ -needed.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9153353730-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="9153353730-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9153353730-2">(</span><span class="p" data-group-id="9153353730-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9153353730-3">]</span><span class="p" data-group-id="9153353730-2">)</span><span class="p">.</span><span class="w">
│ │ │ +needed.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8872899629-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="8872899629-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8872899629-2">(</span><span class="p" data-group-id="8872899629-3">[</span><span class="ss">format_temps</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8872899629-3">]</span><span class="p" data-group-id="8872899629-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">format_temps</span><span class="p" data-group-id="9153353730-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="9153353730-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9153353730-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="9153353730-5">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="9153353730-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="9153353730-6">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9153353730-7">{</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="9153353730-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9153353730-8">(</span><span class="n">Converted_List</span><span class="p" data-group-id="9153353730-8">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">print_max_and_min</span><span class="p" data-group-id="9153353730-9">(</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="9153353730-9">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9153353730-10">(</span><span class="p" data-group-id="9153353730-11">[</span><span class="p" data-group-id="9153353730-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-13">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9153353730-13">}</span><span class="p" data-group-id="9153353730-12">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9153353730-11">]</span><span class="p" data-group-id="9153353730-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9153353730-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-16">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="9153353730-16">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="9153353730-15">}</span><span class="p" data-group-id="9153353730-14">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9153353730-17">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9153353730-18">(</span><span class="n">Rest</span><span class="p" data-group-id="9153353730-18">)</span><span class="p" data-group-id="9153353730-17">]</span><span class="p">;</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9153353730-19">(</span><span class="p" data-group-id="9153353730-20">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9153353730-20">]</span><span class="p" data-group-id="9153353730-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9153353730-21">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9153353730-22">(</span><span class="n">Rest</span><span class="p" data-group-id="9153353730-22">)</span><span class="p" data-group-id="9153353730-21">]</span><span class="p">;</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="9153353730-23">(</span><span class="p" data-group-id="9153353730-24">[</span><span class="p" data-group-id="9153353730-24">]</span><span class="p" data-group-id="9153353730-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9153353730-25">[</span><span class="p" data-group-id="9153353730-25">]</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="9153353730-26">(</span><span class="p" data-group-id="9153353730-27">[</span><span class="p" data-group-id="9153353730-28">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-29">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9153353730-29">}</span><span class="p" data-group-id="9153353730-28">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9153353730-27">]</span><span class="p" data-group-id="9153353730-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9153353730-30">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-31">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9153353730-31">]</span><span class="p" data-group-id="9153353730-30">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">print_temp</span><span class="p" data-group-id="9153353730-32">(</span><span class="n">Rest</span><span class="p" data-group-id="9153353730-32">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">print_temp</span><span class="p" data-group-id="9153353730-33">(</span><span class="p" data-group-id="9153353730-34">[</span><span class="p" data-group-id="9153353730-34">]</span><span class="p" data-group-id="9153353730-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">format_temps</span><span class="p" data-group-id="8872899629-4">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8872899629-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Converted_List</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8872899629-5">(</span><span class="n">List_of_cities</span><span class="p" data-group-id="8872899629-5">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="8872899629-6">(</span><span class="n">Converted_List</span><span class="p" data-group-id="8872899629-6">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8872899629-7">{</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="8872899629-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8872899629-8">(</span><span class="n">Converted_List</span><span class="p" data-group-id="8872899629-8">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">print_max_and_min</span><span class="p" data-group-id="8872899629-9">(</span><span class="n">Max_city</span><span class="p">,</span><span class="w"> </span><span class="n">Min_city</span><span class="p" data-group-id="8872899629-9">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8872899629-10">(</span><span class="p" data-group-id="8872899629-11">[</span><span class="p" data-group-id="8872899629-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-13">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8872899629-13">}</span><span class="p" data-group-id="8872899629-12">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8872899629-11">]</span><span class="p" data-group-id="8872899629-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Converted_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8872899629-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-16">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="mi">32</span><span class="p" data-group-id="8872899629-16">)</span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="8872899629-15">}</span><span class="p" data-group-id="8872899629-14">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8872899629-17">[</span><span class="n">Converted_City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8872899629-18">(</span><span class="n">Rest</span><span class="p" data-group-id="8872899629-18">)</span><span class="p" data-group-id="8872899629-17">]</span><span class="p">;</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8872899629-19">(</span><span class="p" data-group-id="8872899629-20">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8872899629-20">]</span><span class="p" data-group-id="8872899629-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8872899629-21">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8872899629-22">(</span><span class="n">Rest</span><span class="p" data-group-id="8872899629-22">)</span><span class="p" data-group-id="8872899629-21">]</span><span class="p">;</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="8872899629-23">(</span><span class="p" data-group-id="8872899629-24">[</span><span class="p" data-group-id="8872899629-24">]</span><span class="p" data-group-id="8872899629-23">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8872899629-25">[</span><span class="p" data-group-id="8872899629-25">]</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="8872899629-26">(</span><span class="p" data-group-id="8872899629-27">[</span><span class="p" data-group-id="8872899629-28">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-29">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8872899629-29">}</span><span class="p" data-group-id="8872899629-28">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8872899629-27">]</span><span class="p" data-group-id="8872899629-26">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8872899629-30">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> c</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-31">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8872899629-31">]</span><span class="p" data-group-id="8872899629-30">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">print_temp</span><span class="p" data-group-id="8872899629-32">(</span><span class="n">Rest</span><span class="p" data-group-id="8872899629-32">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">print_temp</span><span class="p" data-group-id="8872899629-33">(</span><span class="p" data-group-id="8872899629-34">[</span><span class="p" data-group-id="8872899629-34">]</span><span class="p" data-group-id="8872899629-33">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9153353730-35">(</span><span class="p" data-group-id="9153353730-36">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9153353730-36">]</span><span class="p" data-group-id="9153353730-35">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9153353730-37">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p" data-group-id="9153353730-37">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8872899629-35">(</span><span class="p" data-group-id="8872899629-36">[</span><span class="n">City</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8872899629-36">]</span><span class="p" data-group-id="8872899629-35">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8872899629-37">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">City</span><span class="p" data-group-id="8872899629-37">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9153353730-38">(</span><span class="p" data-group-id="9153353730-39">[</span><span class="p" data-group-id="9153353730-40">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-41">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9153353730-41">}</span><span class="p" data-group-id="9153353730-40">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="9153353730-39">]</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="9153353730-42">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-43">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="9153353730-43">}</span><span class="p" data-group-id="9153353730-42">}</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="9153353730-44">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-45">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="9153353730-45">}</span><span class="p" data-group-id="9153353730-44">}</span><span class="p" data-group-id="9153353730-38">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8872899629-38">(</span><span class="p" data-group-id="8872899629-39">[</span><span class="p" data-group-id="8872899629-40">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-41">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8872899629-41">}</span><span class="p" data-group-id="8872899629-40">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="8872899629-39">]</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="8872899629-42">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-43">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="8872899629-43">}</span><span class="p" data-group-id="8872899629-42">}</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="8872899629-44">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-45">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="8872899629-45">}</span><span class="p" data-group-id="8872899629-44">}</span><span class="p" data-group-id="8872899629-38">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">Temp</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="n">Max_Temp</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9153353730-46">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-47">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9153353730-47">}</span><span class="p" data-group-id="9153353730-46">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │ +            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8872899629-46">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-47">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8872899629-47">}</span><span class="p" data-group-id="8872899629-46">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9153353730-48">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-49">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="9153353730-49">}</span><span class="p" data-group-id="9153353730-48">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │ +            </span><span class="n">Max_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8872899629-48">{</span><span class="n">Max_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-49">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_Temp</span><span class="p" data-group-id="8872899629-49">}</span><span class="p" data-group-id="8872899629-48">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │           </span><span class="n">Temp</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Min_Temp</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9153353730-50">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-51">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="9153353730-51">}</span><span class="p" data-group-id="9153353730-50">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │ +            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8872899629-50">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-51">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="8872899629-51">}</span><span class="p" data-group-id="8872899629-50">}</span><span class="p">;</span><span class="w">           </span><span class="c1">% Change</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9153353730-52">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-53">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="9153353730-53">}</span><span class="p" data-group-id="9153353730-52">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │ +            </span><span class="n">Min_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8872899629-52">{</span><span class="n">Min_Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-53">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_Temp</span><span class="p" data-group-id="8872899629-53">}</span><span class="p" data-group-id="8872899629-52">}</span><span class="w"> </span><span class="c1">% Unchanged</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9153353730-54">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="9153353730-54">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8872899629-54">(</span><span class="n">Rest</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="8872899629-54">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="9153353730-55">(</span><span class="p" data-group-id="9153353730-56">[</span><span class="p" data-group-id="9153353730-56">]</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="9153353730-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9153353730-57">{</span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="9153353730-57">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">find_max_and_min</span><span class="p" data-group-id="8872899629-55">(</span><span class="p" data-group-id="8872899629-56">[</span><span class="p" data-group-id="8872899629-56">]</span><span class="p">,</span><span class="w"> </span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="8872899629-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8872899629-57">{</span><span class="n">Max_City</span><span class="p">,</span><span class="w"> </span><span class="n">Min_City</span><span class="p" data-group-id="8872899629-57">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">print_max_and_min</span><span class="p" data-group-id="9153353730-58">(</span><span class="p" data-group-id="9153353730-59">{</span><span class="n">Max_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-60">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_temp</span><span class="p" data-group-id="9153353730-60">}</span><span class="p" data-group-id="9153353730-59">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-61">{</span><span class="n">Min_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-62">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_temp</span><span class="p" data-group-id="9153353730-62">}</span><span class="p" data-group-id="9153353730-61">}</span><span class="p" data-group-id="9153353730-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9153353730-63">(</span><span class="s">&quot;Max temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-64">[</span><span class="n">Max_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Max_name</span><span class="p" data-group-id="9153353730-64">]</span><span class="p" data-group-id="9153353730-63">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9153353730-65">(</span><span class="s">&quot;Min temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9153353730-66">[</span><span class="n">Min_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Min_name</span><span class="p" data-group-id="9153353730-66">]</span><span class="p" data-group-id="9153353730-65">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">58&gt; </span><span class="nf">c</span><span class="p" data-group-id="7706237694-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="7706237694-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7706237694-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="7706237694-2">}</span><span class="gp unselectable">
│ │ │ -59&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="7706237694-3">(</span><span class="p" data-group-id="7706237694-4">[</span><span class="p" data-group-id="7706237694-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="7706237694-6">}</span><span class="p" data-group-id="7706237694-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="7706237694-8">}</span><span class="p" data-group-id="7706237694-7">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7706237694-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="7706237694-10">}</span><span class="p" data-group-id="7706237694-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="7706237694-12">}</span><span class="p" data-group-id="7706237694-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7706237694-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="7706237694-14">}</span><span class="p" data-group-id="7706237694-13">}</span><span class="p" data-group-id="7706237694-4">]</span><span class="p" data-group-id="7706237694-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">print_max_and_min</span><span class="p" data-group-id="8872899629-58">(</span><span class="p" data-group-id="8872899629-59">{</span><span class="n">Max_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-60">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Max_temp</span><span class="p" data-group-id="8872899629-60">}</span><span class="p" data-group-id="8872899629-59">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-61">{</span><span class="n">Min_name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-62">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Min_temp</span><span class="p" data-group-id="8872899629-62">}</span><span class="p" data-group-id="8872899629-61">}</span><span class="p" data-group-id="8872899629-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8872899629-63">(</span><span class="s">&quot;Max temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-64">[</span><span class="n">Max_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Max_name</span><span class="p" data-group-id="8872899629-64">]</span><span class="p" data-group-id="8872899629-63">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8872899629-65">(</span><span class="s">&quot;Min temperature was </span><span class="si">~w</span><span class="s"> c in </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8872899629-66">[</span><span class="n">Min_temp</span><span class="p">,</span><span class="w"> </span><span class="n">Min_name</span><span class="p" data-group-id="8872899629-66">]</span><span class="p" data-group-id="8872899629-65">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">58&gt; </span><span class="nf">c</span><span class="p" data-group-id="4247767786-1">(</span><span class="ss">tut7</span><span class="p" data-group-id="4247767786-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4247767786-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">tut7</span><span class="p" data-group-id="4247767786-2">}</span><span class="gp unselectable">
│ │ │ +59&gt; </span><span class="nc">tut7</span><span class="p">:</span><span class="nf">format_temps</span><span class="p" data-group-id="4247767786-3">(</span><span class="p" data-group-id="4247767786-4">[</span><span class="p" data-group-id="4247767786-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="4247767786-6">}</span><span class="p" data-group-id="4247767786-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="4247767786-8">}</span><span class="p" data-group-id="4247767786-7">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4247767786-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="4247767786-10">}</span><span class="p" data-group-id="4247767786-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="4247767786-12">}</span><span class="p" data-group-id="4247767786-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4247767786-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="4247767786-14">}</span><span class="p" data-group-id="4247767786-13">}</span><span class="p" data-group-id="4247767786-4">]</span><span class="p" data-group-id="4247767786-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="o">-</span><span class="mi">4</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="o">-</span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="mf">2.2222222222222223</span><span class="w"> </span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="n">Max</span><span class="w"> </span><span class="ss">temperature</span><span class="w"> </span><span class="ss">was</span><span class="w"> </span><span class="mf">21.11111111111111</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">cape_town</span><span class="w">
│ │ │  </span><span class="n">Min</span><span class="w"> </span><span class="ss">temperature</span><span class="w"> </span><span class="ss">was</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">moscow</span><span class="w">
│ │ │ @@ -773,88 +773,88 @@
│ │ │          Action 4
│ │ │  end</code></pre><p>Notice that there is no <code class="inline">;</code> before <code class="inline">end</code>. Conditions do the same as guards, that
│ │ │  is, tests that succeed or fail. Erlang starts at the top and tests until it
│ │ │  finds a condition that succeeds. Then it evaluates (performs) the action
│ │ │  following the condition and ignores all other conditions and actions before the
│ │ │  <code class="inline">end</code>. If no condition matches, a run-time failure occurs. A condition that
│ │ │  always succeeds is the atom <code class="inline">true</code>. This is often used last in an <code class="inline">if</code>, meaning,
│ │ │ -do the action following the <code class="inline">true</code> if all other conditions have failed.</p><p>The following is a short program to show the workings of <code class="inline">if</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8647258075-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="8647258075-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8647258075-2">(</span><span class="p" data-group-id="8647258075-3">[</span><span class="ss">test_if</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8647258075-3">]</span><span class="p" data-group-id="8647258075-2">)</span><span class="p">.</span><span class="w">
│ │ │ +do the action following the <code class="inline">true</code> if all other conditions have failed.</p><p>The following is a short program to show the workings of <code class="inline">if</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7269297806-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="7269297806-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7269297806-2">(</span><span class="p" data-group-id="7269297806-3">[</span><span class="ss">test_if</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7269297806-3">]</span><span class="p" data-group-id="7269297806-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">test_if</span><span class="p" data-group-id="8647258075-4">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="8647258075-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">test_if</span><span class="p" data-group-id="7269297806-4">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="7269297806-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8647258075-5">(</span><span class="s">&quot;A == 5</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8647258075-6">[</span><span class="p" data-group-id="8647258075-6">]</span><span class="p" data-group-id="8647258075-5">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7269297806-5">(</span><span class="s">&quot;A == 5</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7269297806-6">[</span><span class="p" data-group-id="7269297806-6">]</span><span class="p" data-group-id="7269297806-5">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="ss">a_equals_5</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">6</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8647258075-7">(</span><span class="s">&quot;B == 6</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8647258075-8">[</span><span class="p" data-group-id="8647258075-8">]</span><span class="p" data-group-id="8647258075-7">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7269297806-7">(</span><span class="s">&quot;B == 6</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7269297806-8">[</span><span class="p" data-group-id="7269297806-8">]</span><span class="p" data-group-id="7269297806-7">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="ss">b_equals_6</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">                      </span><span class="c1">%That is A equals 2 and B equals 3</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8647258075-9">(</span><span class="s">&quot;A == 2, B == 3</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8647258075-10">[</span><span class="p" data-group-id="8647258075-10">]</span><span class="p" data-group-id="8647258075-9">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7269297806-9">(</span><span class="s">&quot;A == 2, B == 3</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7269297806-10">[</span><span class="p" data-group-id="7269297806-10">]</span><span class="p" data-group-id="7269297806-9">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="ss">a_equals_2_b_equals_3</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">7</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">                     </span><span class="c1">%That is A equals 1 or B equals 7</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8647258075-11">(</span><span class="s">&quot;A == 1 ; B == 7</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8647258075-12">[</span><span class="p" data-group-id="8647258075-12">]</span><span class="p" data-group-id="8647258075-11">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7269297806-11">(</span><span class="s">&quot;A == 1 ; B == 7</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7269297806-12">[</span><span class="p" data-group-id="7269297806-12">]</span><span class="p" data-group-id="7269297806-11">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="ss">a_equals_1_or_b_equals_7</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Testing this program gives:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">60&gt; </span><span class="nf">c</span><span class="p" data-group-id="1461959682-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="1461959682-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1461959682-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut9</span><span class="p" data-group-id="1461959682-2">}</span><span class="gp unselectable">
│ │ │ -61&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1461959682-3">(</span><span class="mi">5</span><span class="p">,</span><span class="mi">33</span><span class="p" data-group-id="1461959682-3">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><p>Testing this program gives:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">60&gt; </span><span class="nf">c</span><span class="p" data-group-id="2162775759-1">(</span><span class="ss">tut9</span><span class="p" data-group-id="2162775759-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2162775759-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut9</span><span class="p" data-group-id="2162775759-2">}</span><span class="gp unselectable">
│ │ │ +61&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="2162775759-3">(</span><span class="mi">5</span><span class="p">,</span><span class="mi">33</span><span class="p" data-group-id="2162775759-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │  </span><span class="ss">a_equals_5</span><span class="gp unselectable">
│ │ │ -62&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1461959682-4">(</span><span class="mi">33</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="1461959682-4">)</span><span class="p">.</span><span class="w">
│ │ │ +62&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="2162775759-4">(</span><span class="mi">33</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2162775759-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">6</span><span class="w">
│ │ │  </span><span class="ss">b_equals_6</span><span class="gp unselectable">
│ │ │ -63&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1461959682-5">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1461959682-5">)</span><span class="p">.</span><span class="w">
│ │ │ +63&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="2162775759-5">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="2162775759-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">3</span><span class="w">
│ │ │  </span><span class="ss">a_equals_2_b_equals_3</span><span class="gp unselectable">
│ │ │ -64&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1461959682-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="1461959682-6">)</span><span class="p">.</span><span class="w">
│ │ │ +64&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="2162775759-6">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="2162775759-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">7</span><span class="w">
│ │ │  </span><span class="ss">a_equals_1_or_b_equals_7</span><span class="gp unselectable">
│ │ │ -65&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1461959682-7">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p" data-group-id="1461959682-7">)</span><span class="p">.</span><span class="w">
│ │ │ +65&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="2162775759-7">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p" data-group-id="2162775759-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="n">A</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">;</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">7</span><span class="w">
│ │ │  </span><span class="ss">a_equals_1_or_b_equals_7</span><span class="gp unselectable">
│ │ │ -66&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="1461959682-8">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="1461959682-8">)</span><span class="p">.</span><span class="w">
│ │ │ +66&gt; </span><span class="nc">tut9</span><span class="p">:</span><span class="nf">test_if</span><span class="p" data-group-id="2162775759-8">(</span><span class="mi">33</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="2162775759-8">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: no true branch found when evaluating an if expression
│ │ │       in function  tut9:test_if/2 (tut9.erl, line 5)</span></code></pre><p>Notice that <code class="inline">tut9:test_if(33,33)</code> does not cause any condition to succeed. This
│ │ │  leads to the run time error <code class="inline">if_clause</code>, here nicely formatted by the shell. See
│ │ │  <a href="../../doc/system/expressions.html">Guard Sequences</a> for details of the many guard tests
│ │ │  available.</p><p><code class="inline">case</code> is another construct in Erlang. Recall that the <code class="inline">convert_length</code> function
│ │ │ -was written as:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_length</span><span class="p" data-group-id="9809424444-1">(</span><span class="p" data-group-id="9809424444-2">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="9809424444-2">}</span><span class="p" data-group-id="9809424444-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9809424444-3">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9809424444-3">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="9809424444-4">(</span><span class="p" data-group-id="9809424444-5">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="9809424444-5">}</span><span class="p" data-group-id="9809424444-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9809424444-6">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="9809424444-6">}</span><span class="p">.</span></code></pre><p>The same program can also be written as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3630809457-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="3630809457-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3630809457-2">(</span><span class="p" data-group-id="3630809457-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3630809457-3">]</span><span class="p" data-group-id="3630809457-2">)</span><span class="p">.</span><span class="w">
│ │ │ +was written as:</p><pre><code class="makeup erlang" translate="no"><span class="nf">convert_length</span><span class="p" data-group-id="1890479004-1">(</span><span class="p" data-group-id="1890479004-2">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="1890479004-2">}</span><span class="p" data-group-id="1890479004-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1890479004-3">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="1890479004-3">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="1890479004-4">(</span><span class="p" data-group-id="1890479004-5">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="1890479004-5">}</span><span class="p" data-group-id="1890479004-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1890479004-6">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="1890479004-6">}</span><span class="p">.</span></code></pre><p>The same program can also be written as:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6982081341-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="6982081341-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6982081341-2">(</span><span class="p" data-group-id="6982081341-3">[</span><span class="ss">convert_length</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6982081341-3">]</span><span class="p" data-group-id="6982081341-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">convert_length</span><span class="p" data-group-id="3630809457-4">(</span><span class="n">Length</span><span class="p" data-group-id="3630809457-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">convert_length</span><span class="p" data-group-id="6982081341-4">(</span><span class="n">Length</span><span class="p" data-group-id="6982081341-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="3630809457-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="3630809457-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="3630809457-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="3630809457-6">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="3630809457-7">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="3630809457-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="3630809457-8">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="3630809457-8">}</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">67&gt; </span><span class="nf">c</span><span class="p" data-group-id="6297185502-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="6297185502-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6297185502-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut10</span><span class="p" data-group-id="6297185502-2">}</span><span class="gp unselectable">
│ │ │ -68&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="6297185502-3">(</span><span class="p" data-group-id="6297185502-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="6297185502-4">}</span><span class="p" data-group-id="6297185502-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6297185502-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">15.24</span><span class="p" data-group-id="6297185502-5">}</span><span class="gp unselectable">
│ │ │ -69&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="6297185502-6">(</span><span class="p" data-group-id="6297185502-7">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="mf">2.5</span><span class="p" data-group-id="6297185502-7">}</span><span class="p" data-group-id="6297185502-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6297185502-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">0.984251968503937</span><span class="p" data-group-id="6297185502-8">}</span></code></pre><p>Both <code class="inline">case</code> and <code class="inline">if</code> have <em>return values</em>, that is, in the above example <code class="inline">case</code>
│ │ │ +        </span><span class="p" data-group-id="6982081341-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p" data-group-id="6982081341-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6982081341-6">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="6982081341-6">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="6982081341-7">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p" data-group-id="6982081341-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6982081341-8">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mf">2.54</span><span class="p" data-group-id="6982081341-8">}</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">67&gt; </span><span class="nf">c</span><span class="p" data-group-id="3148944937-1">(</span><span class="ss">tut10</span><span class="p" data-group-id="3148944937-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3148944937-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut10</span><span class="p" data-group-id="3148944937-2">}</span><span class="gp unselectable">
│ │ │ +68&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="3148944937-3">(</span><span class="p" data-group-id="3148944937-4">{</span><span class="ss">inch</span><span class="p">,</span><span class="w"> </span><span class="mi">6</span><span class="p" data-group-id="3148944937-4">}</span><span class="p" data-group-id="3148944937-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3148944937-5">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="mf">15.24</span><span class="p" data-group-id="3148944937-5">}</span><span class="gp unselectable">
│ │ │ +69&gt; </span><span class="nc">tut10</span><span class="p">:</span><span class="nf">convert_length</span><span class="p" data-group-id="3148944937-6">(</span><span class="p" data-group-id="3148944937-7">{</span><span class="ss">centimeter</span><span class="p">,</span><span class="w"> </span><span class="mf">2.5</span><span class="p" data-group-id="3148944937-7">}</span><span class="p" data-group-id="3148944937-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3148944937-8">{</span><span class="ss">inch</span><span class="p">,</span><span class="mf">0.984251968503937</span><span class="p" data-group-id="3148944937-8">}</span></code></pre><p>Both <code class="inline">case</code> and <code class="inline">if</code> have <em>return values</em>, that is, in the above example <code class="inline">case</code>
│ │ │  returned either <code class="inline">{inch,X/2.54}</code> or <code class="inline">{centimeter,Y*2.54}</code>. The behaviour of
│ │ │  <code class="inline">case</code> can also be modified by using guards. The following example clarifies
│ │ │  this. It tells us the length of a month, given the year. The year must be known,
│ │ │ -since February has 29 days in a leap year.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8467028357-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="8467028357-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8467028357-2">(</span><span class="p" data-group-id="8467028357-3">[</span><span class="ss">month_length</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8467028357-3">]</span><span class="p" data-group-id="8467028357-2">)</span><span class="p">.</span><span class="w">
│ │ │ +since February has 29 days in a leap year.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5669616143-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="5669616143-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5669616143-2">(</span><span class="p" data-group-id="5669616143-3">[</span><span class="ss">month_length</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5669616143-3">]</span><span class="p" data-group-id="5669616143-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">month_length</span><span class="p" data-group-id="8467028357-4">(</span><span class="n">Year</span><span class="p">,</span><span class="w"> </span><span class="n">Month</span><span class="p" data-group-id="8467028357-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">month_length</span><span class="p" data-group-id="5669616143-4">(</span><span class="n">Year</span><span class="p">,</span><span class="w"> </span><span class="n">Month</span><span class="p" data-group-id="5669616143-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% All years divisible by 400 are leap</span><span class="w">
│ │ │      </span><span class="c1">%% Years divisible by 100 are not leap (except the 400 rule above)</span><span class="w">
│ │ │      </span><span class="c1">%% Years divisible by 4 are leap (except the 100 rule above)</span><span class="w">
│ │ │      </span><span class="n">Leap</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">if</span><span class="w">
│ │ │ -        </span><span class="nf">trunc</span><span class="p" data-group-id="8467028357-5">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="8467028357-5">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nf">trunc</span><span class="p" data-group-id="5669616143-5">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="5669616143-5">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">leap</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="nf">trunc</span><span class="p" data-group-id="8467028357-6">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="8467028357-6">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">100</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nf">trunc</span><span class="p" data-group-id="5669616143-6">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">100</span><span class="p" data-group-id="5669616143-6">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">100</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">not_leap</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="nf">trunc</span><span class="p" data-group-id="8467028357-7">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="8467028357-7">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">4</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nf">trunc</span><span class="p" data-group-id="5669616143-7">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="5669616143-7">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">4</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">leap</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">not_leap</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Month</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">sep</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">30</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">apr</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">30</span><span class="p">;</span><span class="w">
│ │ │ @@ -865,152 +865,152 @@
│ │ │          </span><span class="ss">jan</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">mar</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">may</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">jul</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">aug</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">oct</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="ss">dec</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">31</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">70&gt; </span><span class="nf">c</span><span class="p" data-group-id="3505808717-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="3505808717-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3505808717-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut11</span><span class="p" data-group-id="3505808717-2">}</span><span class="gp unselectable">
│ │ │ -71&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="3505808717-3">(</span><span class="mi">2004</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="3505808717-3">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">70&gt; </span><span class="nf">c</span><span class="p" data-group-id="7112334532-1">(</span><span class="ss">tut11</span><span class="p" data-group-id="7112334532-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7112334532-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut11</span><span class="p" data-group-id="7112334532-2">}</span><span class="gp unselectable">
│ │ │ +71&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="7112334532-3">(</span><span class="mi">2004</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="7112334532-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">29</span><span class="gp unselectable">
│ │ │ -72&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="3505808717-4">(</span><span class="mi">2003</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="3505808717-4">)</span><span class="p">.</span><span class="w">
│ │ │ +72&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="7112334532-4">(</span><span class="mi">2003</span><span class="p">,</span><span class="w"> </span><span class="ss">feb</span><span class="p" data-group-id="7112334532-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">28</span><span class="gp unselectable">
│ │ │ -73&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="3505808717-5">(</span><span class="mi">1947</span><span class="p">,</span><span class="w"> </span><span class="ss">aug</span><span class="p" data-group-id="3505808717-5">)</span><span class="p">.</span><span class="w">
│ │ │ +73&gt; </span><span class="nc">tut11</span><span class="p">:</span><span class="nf">month_length</span><span class="p" data-group-id="7112334532-5">(</span><span class="mi">1947</span><span class="p">,</span><span class="w"> </span><span class="ss">aug</span><span class="p" data-group-id="7112334532-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">31</span></code></pre><h2 id="built-in-functions-bifs" class="section-heading">
│ │ │    <a href="#built-in-functions-bifs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Built-In Functions (BIFs)</span>
│ │ │  </h2>
│ │ │  <p>BIFs are functions that for some reason are built-in to the Erlang virtual
│ │ │  machine. BIFs often implement functionality that is impossible or is too
│ │ │  inefficient to implement in Erlang. Some BIFs can be called using the function
│ │ │  name only but they are by default belonging to the <code class="inline">erlang</code> module. For example,
│ │ │  the call to the BIF <code class="inline">trunc</code> below is equivalent to a call to <code class="inline">erlang:trunc</code>.</p><p>As shown, first it is checked if a year is leap. If a year is divisible by 400,
│ │ │  it is a leap year. To determine this, first divide the year by 400 and use the
│ │ │  BIF <code class="inline">trunc</code> (more about this later) to cut off any decimals. Then multiply by
│ │ │  400 again and see if the same value is returned again. For example, year 2004:</p><pre><code class="makeup erlang" translate="no"><span class="mi">2004</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mf">5.01</span><span class="w">
│ │ │ -</span><span class="nf">trunc</span><span class="p" data-group-id="7371482753-1">(</span><span class="mf">5.01</span><span class="p" data-group-id="7371482753-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │ +</span><span class="nf">trunc</span><span class="p" data-group-id="7842099549-1">(</span><span class="mf">5.01</span><span class="p" data-group-id="7842099549-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │  </span><span class="mi">5</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2000</span></code></pre><p>2000 is not the same as 2004, so 2004 is not divisible by 400. Year 2000:</p><pre><code class="makeup erlang" translate="no"><span class="mi">2000</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mf">5.0</span><span class="w">
│ │ │ -</span><span class="nf">trunc</span><span class="p" data-group-id="3024219606-1">(</span><span class="mf">5.0</span><span class="p" data-group-id="3024219606-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │ +</span><span class="nf">trunc</span><span class="p" data-group-id="6342989024-1">(</span><span class="mf">5.0</span><span class="p" data-group-id="6342989024-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │  </span><span class="mi">5</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">2000</span></code></pre><p>That is, a leap year. The next two <code class="inline">trunc</code>-tests evaluate if the year is
│ │ │  divisible by 100 or 4 in the same way. The first <code class="inline">if</code> returns <code class="inline">leap</code> or
│ │ │  <code class="inline">not_leap</code>, which lands up in the variable <code class="inline">Leap</code>. This variable is used in the
│ │ │  guard for <code class="inline">feb</code> in the following <code class="inline">case</code> that tells us how long the month is.</p><p>This example showed the use of <code class="inline">trunc</code>. It is easier to use the Erlang operator
│ │ │  <code class="inline">rem</code> that gives the remainder after division, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">74&gt; </span><span class="mi">2004</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">400</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">4</span></code></pre><p>So instead of writing:</p><pre><code class="makeup erlang" translate="no"><span class="nf">trunc</span><span class="p" data-group-id="4126101107-1">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="4126101107-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="mi">4</span></code></pre><p>So instead of writing:</p><pre><code class="makeup erlang" translate="no"><span class="nf">trunc</span><span class="p" data-group-id="2918501582-1">(</span><span class="n">Year</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">400</span><span class="p" data-group-id="2918501582-1">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">Year</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">leap</span><span class="p">;</span></code></pre><p>it can be written:</p><pre><code class="makeup erlang" translate="no"><span class="n">Year</span><span class="w"> </span><span class="ow">rem</span><span class="w"> </span><span class="mi">400</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">leap</span><span class="p">;</span></code></pre><p>There are many other BIFs such as <code class="inline">trunc</code>. Only a few BIFs can be used in
│ │ │  guards, and you cannot use functions you have defined yourself in guards. (see
│ │ │  <a href="../../doc/system/expressions.html">Guard Sequences</a>) (For advanced readers: This is to
│ │ │  ensure that guards do not have side effects.) Let us play with a few of these
│ │ │ -functions in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">75&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="9834873585-1">(</span><span class="mf">5.6</span><span class="p" data-group-id="9834873585-1">)</span><span class="p">.</span><span class="w">
│ │ │ +functions in the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">75&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="8786520574-1">(</span><span class="mf">5.6</span><span class="p" data-group-id="8786520574-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">5</span><span class="gp unselectable">
│ │ │ -76&gt; </span><span class="nf">round</span><span class="p" data-group-id="9834873585-2">(</span><span class="mf">5.6</span><span class="p" data-group-id="9834873585-2">)</span><span class="p">.</span><span class="w">
│ │ │ +76&gt; </span><span class="nf">round</span><span class="p" data-group-id="8786520574-2">(</span><span class="mf">5.6</span><span class="p" data-group-id="8786520574-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">6</span><span class="gp unselectable">
│ │ │ -77&gt; </span><span class="nf">length</span><span class="p" data-group-id="9834873585-3">(</span><span class="p" data-group-id="9834873585-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="9834873585-4">]</span><span class="p" data-group-id="9834873585-3">)</span><span class="p">.</span><span class="w">
│ │ │ +77&gt; </span><span class="nf">length</span><span class="p" data-group-id="8786520574-3">(</span><span class="p" data-group-id="8786520574-4">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p">,</span><span class="ss">d</span><span class="p" data-group-id="8786520574-4">]</span><span class="p" data-group-id="8786520574-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4</span><span class="gp unselectable">
│ │ │ -78&gt; </span><span class="nf">float</span><span class="p" data-group-id="9834873585-5">(</span><span class="mi">5</span><span class="p" data-group-id="9834873585-5">)</span><span class="p">.</span><span class="w">
│ │ │ +78&gt; </span><span class="nf">float</span><span class="p" data-group-id="8786520574-5">(</span><span class="mi">5</span><span class="p" data-group-id="8786520574-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">5.0</span><span class="gp unselectable">
│ │ │ -79&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="9834873585-6">(</span><span class="ss">hello</span><span class="p" data-group-id="9834873585-6">)</span><span class="p">.</span><span class="w">
│ │ │ +79&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="8786520574-6">(</span><span class="ss">hello</span><span class="p" data-group-id="8786520574-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -80&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="9834873585-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="9834873585-7">)</span><span class="p">.</span><span class="w">
│ │ │ +80&gt; </span><span class="nf">is_atom</span><span class="p" data-group-id="8786520574-7">(</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="8786520574-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ -81&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="9834873585-8">(</span><span class="p" data-group-id="9834873585-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9834873585-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="9834873585-10">}</span><span class="p" data-group-id="9834873585-9">}</span><span class="p" data-group-id="9834873585-8">)</span><span class="p">.</span><span class="w">
│ │ │ +81&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="8786520574-8">(</span><span class="p" data-group-id="8786520574-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786520574-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="8786520574-10">}</span><span class="p" data-group-id="8786520574-9">}</span><span class="p" data-group-id="8786520574-8">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -82&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="9834873585-11">(</span><span class="p" data-group-id="9834873585-12">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9834873585-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="9834873585-13">}</span><span class="p" data-group-id="9834873585-12">]</span><span class="p" data-group-id="9834873585-11">)</span><span class="p">.</span><span class="w">
│ │ │ +82&gt; </span><span class="nf">is_tuple</span><span class="p" data-group-id="8786520574-11">(</span><span class="p" data-group-id="8786520574-12">[</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8786520574-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="mi">30</span><span class="p" data-group-id="8786520574-13">}</span><span class="p" data-group-id="8786520574-12">]</span><span class="p" data-group-id="8786520574-11">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span></code></pre><p>All of these can be used in guards. Now for some BIFs that cannot be used in
│ │ │ -guards:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">83&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="0646276903-1">(</span><span class="ss">hello</span><span class="p" data-group-id="0646276903-1">)</span><span class="p">.</span><span class="w">
│ │ │ +guards:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">83&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="2252618479-1">(</span><span class="ss">hello</span><span class="p" data-group-id="2252618479-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;hello&quot;</span><span class="gp unselectable">
│ │ │ -84&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="0646276903-2">(</span><span class="s">&quot;goodbye&quot;</span><span class="p" data-group-id="0646276903-2">)</span><span class="p">.</span><span class="w">
│ │ │ +84&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="2252618479-2">(</span><span class="s">&quot;goodbye&quot;</span><span class="p" data-group-id="2252618479-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">goodbye</span><span class="gp unselectable">
│ │ │ -85&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="0646276903-3">(</span><span class="mi">22</span><span class="p" data-group-id="0646276903-3">)</span><span class="p">.</span><span class="w">
│ │ │ +85&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="2252618479-3">(</span><span class="mi">22</span><span class="p" data-group-id="2252618479-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;22&quot;</span></code></pre><p>These three BIFs do conversions that would be difficult (or impossible) to do in
│ │ │  Erlang.</p><h2 id="higher-order-functions-funs" class="section-heading">
│ │ │    <a href="#higher-order-functions-funs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Higher-Order Functions (Funs)</span>
│ │ │  </h2>
│ │ │  <p>Erlang, like most modern functional programming languages, has higher-order
│ │ │ -functions. Here is an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">86&gt; </span><span class="n">Xf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4184347286-1">(</span><span class="n">X</span><span class="p" data-group-id="4184347286-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +functions. Here is an example using the shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">86&gt; </span><span class="n">Xf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1558819378-1">(</span><span class="n">X</span><span class="p" data-group-id="1558819378-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">5.123085357</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -87&gt; </span><span class="n">Xf</span><span class="p" data-group-id="4184347286-2">(</span><span class="mi">5</span><span class="p" data-group-id="4184347286-2">)</span><span class="p">.</span><span class="w">
│ │ │ +87&gt; </span><span class="n">Xf</span><span class="p" data-group-id="1558819378-2">(</span><span class="mi">5</span><span class="p" data-group-id="1558819378-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">10</span></code></pre><p>Here is defined a function that doubles the value of a number and assigned this
│ │ │  function to a variable. Thus <code class="inline">Xf(5)</code> returns value 10. Two useful functions when
│ │ │ -working with lists are <code class="inline">foreach</code> and <code class="inline">map</code>, which are defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="5460582385-1">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5460582385-2">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="5460582385-2">]</span><span class="p" data-group-id="5460582385-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">Fun</span><span class="p" data-group-id="5460582385-3">(</span><span class="n">First</span><span class="p" data-group-id="5460582385-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">foreach</span><span class="p" data-group-id="5460582385-4">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="5460582385-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">foreach</span><span class="p" data-group-id="5460582385-5">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5460582385-6">[</span><span class="p" data-group-id="5460582385-6">]</span><span class="p" data-group-id="5460582385-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +working with lists are <code class="inline">foreach</code> and <code class="inline">map</code>, which are defined as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">foreach</span><span class="p" data-group-id="6877990612-1">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6877990612-2">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="6877990612-2">]</span><span class="p" data-group-id="6877990612-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">Fun</span><span class="p" data-group-id="6877990612-3">(</span><span class="n">First</span><span class="p" data-group-id="6877990612-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">foreach</span><span class="p" data-group-id="6877990612-4">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="n">Rest</span><span class="p" data-group-id="6877990612-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">foreach</span><span class="p" data-group-id="6877990612-5">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6877990612-6">[</span><span class="p" data-group-id="6877990612-6">]</span><span class="p" data-group-id="6877990612-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="5460582385-7">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5460582385-8">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="5460582385-8">]</span><span class="p" data-group-id="5460582385-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5460582385-9">[</span><span class="n">Fun</span><span class="p" data-group-id="5460582385-10">(</span><span class="n">First</span><span class="p" data-group-id="5460582385-10">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="5460582385-11">(</span><span class="n">Fun</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="5460582385-11">)</span><span class="p" data-group-id="5460582385-9">]</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">map</span><span class="p" data-group-id="5460582385-12">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5460582385-13">[</span><span class="p" data-group-id="5460582385-13">]</span><span class="p" data-group-id="5460582385-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5460582385-14">[</span><span class="p" data-group-id="5460582385-14">]</span><span class="p">.</span></code></pre><p>These two functions are provided in the standard module <code class="inline">lists</code>. <code class="inline">foreach</code> takes
│ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="6877990612-7">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6877990612-8">[</span><span class="n">First</span><span class="p">|</span><span class="n">Rest</span><span class="p" data-group-id="6877990612-8">]</span><span class="p" data-group-id="6877990612-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6877990612-9">[</span><span class="n">Fun</span><span class="p" data-group-id="6877990612-10">(</span><span class="n">First</span><span class="p" data-group-id="6877990612-10">)</span><span class="p">|</span><span class="nf">map</span><span class="p" data-group-id="6877990612-11">(</span><span class="n">Fun</span><span class="p">,</span><span class="n">Rest</span><span class="p" data-group-id="6877990612-11">)</span><span class="p" data-group-id="6877990612-9">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">map</span><span class="p" data-group-id="6877990612-12">(</span><span class="n">Fun</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6877990612-13">[</span><span class="p" data-group-id="6877990612-13">]</span><span class="p" data-group-id="6877990612-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6877990612-14">[</span><span class="p" data-group-id="6877990612-14">]</span><span class="p">.</span></code></pre><p>These two functions are provided in the standard module <code class="inline">lists</code>. <code class="inline">foreach</code> takes
│ │ │  a list and applies a fun to every element in the list. <code class="inline">map</code> creates a new list
│ │ │  by applying a fun to every element in a list. Going back to the shell, <code class="inline">map</code> is
│ │ │ -used and a fun to add 3 to every element of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">88&gt; </span><span class="n">Add_3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="9009272318-1">(</span><span class="n">X</span><span class="p" data-group-id="9009272318-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +used and a fun to add 3 to every element of a list:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">88&gt; </span><span class="n">Add_3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="8335332477-1">(</span><span class="n">X</span><span class="p" data-group-id="8335332477-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">5.123085357</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -89&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="9009272318-2">(</span><span class="n">Add_3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9009272318-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9009272318-3">]</span><span class="p" data-group-id="9009272318-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9009272318-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="9009272318-4">]</span></code></pre><p>Let us (again) print the temperatures in a list of cities:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">90&gt; </span><span class="n">Print_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1534248525-1">(</span><span class="p" data-group-id="1534248525-2">{</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1534248525-3">}</span><span class="p" data-group-id="1534248525-2">}</span><span class="p" data-group-id="1534248525-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1534248525-4">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1534248525-5">[</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="1534248525-5">]</span><span class="p" data-group-id="1534248525-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +89&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="8335332477-2">(</span><span class="n">Add_3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8335332477-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8335332477-3">]</span><span class="p" data-group-id="8335332477-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8335332477-4">[</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8335332477-4">]</span></code></pre><p>Let us (again) print the temperatures in a list of cities:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">90&gt; </span><span class="n">Print_City</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="4740061219-1">(</span><span class="p" data-group-id="4740061219-2">{</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-3">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="4740061219-3">}</span><span class="p" data-group-id="4740061219-2">}</span><span class="p" data-group-id="4740061219-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4740061219-4">(</span><span class="s">&quot;</span><span class="si">~-</span><span class="s">15w </span><span class="si">~w</span><span class="s"> </span><span class="si">~w</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4740061219-5">[</span><span class="n">City</span><span class="p">,</span><span class="w"> </span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="4740061219-5">]</span><span class="p" data-group-id="4740061219-4">)</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">5.123085357</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -91&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="1534248525-6">(</span><span class="n">Print_City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-7">[</span><span class="p" data-group-id="1534248525-8">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-9">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="1534248525-9">}</span><span class="p" data-group-id="1534248525-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-10">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="1534248525-11">}</span><span class="p" data-group-id="1534248525-10">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1534248525-12">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="1534248525-13">}</span><span class="p" data-group-id="1534248525-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-14">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-15">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="1534248525-15">}</span><span class="p" data-group-id="1534248525-14">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-16">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1534248525-17">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="1534248525-17">}</span><span class="p" data-group-id="1534248525-16">}</span><span class="p" data-group-id="1534248525-7">]</span><span class="p" data-group-id="1534248525-6">)</span><span class="p">.</span><span class="w">
│ │ │ +91&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="4740061219-6">(</span><span class="n">Print_City</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-7">[</span><span class="p" data-group-id="4740061219-8">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-9">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="4740061219-9">}</span><span class="p" data-group-id="4740061219-8">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-10">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-11">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="4740061219-11">}</span><span class="p" data-group-id="4740061219-10">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4740061219-12">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="4740061219-13">}</span><span class="p" data-group-id="4740061219-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-14">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-15">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="4740061219-15">}</span><span class="p" data-group-id="4740061219-14">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-16">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4740061219-17">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="4740061219-17">}</span><span class="p" data-group-id="4740061219-16">}</span><span class="p" data-group-id="4740061219-7">]</span><span class="p" data-group-id="4740061219-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">moscow</span><span class="w">          </span><span class="ss">c</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="w">
│ │ │  </span><span class="ss">cape_town</span><span class="w">       </span><span class="ss">f</span><span class="w"> </span><span class="mi">70</span><span class="w">
│ │ │  </span><span class="ss">stockholm</span><span class="w">       </span><span class="ss">c</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="w">
│ │ │  </span><span class="ss">paris</span><span class="w">           </span><span class="ss">f</span><span class="w"> </span><span class="mi">28</span><span class="w">
│ │ │  </span><span class="ss">london</span><span class="w">          </span><span class="ss">f</span><span class="w"> </span><span class="mi">36</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>Let us now define a fun that can be used to go through a list of cities and
│ │ │ -temperatures and transform them all to Celsius.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6552807500-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="6552807500-1">)</span><span class="p">.</span><span class="w">
│ │ │ +temperatures and transform them all to Celsius.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2620593319-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="2620593319-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6552807500-2">(</span><span class="p" data-group-id="6552807500-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6552807500-3">]</span><span class="p" data-group-id="6552807500-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2620593319-2">(</span><span class="p" data-group-id="2620593319-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2620593319-3">]</span><span class="p" data-group-id="2620593319-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="6552807500-4">(</span><span class="p" data-group-id="6552807500-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6552807500-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="6552807500-6">}</span><span class="p" data-group-id="6552807500-5">}</span><span class="p" data-group-id="6552807500-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6552807500-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6552807500-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="6552807500-9">(</span><span class="p" data-group-id="6552807500-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="6552807500-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="6552807500-9">)</span><span class="p" data-group-id="6552807500-8">}</span><span class="p" data-group-id="6552807500-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="6552807500-11">(</span><span class="p" data-group-id="6552807500-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6552807500-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="6552807500-13">}</span><span class="p" data-group-id="6552807500-12">}</span><span class="p" data-group-id="6552807500-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6552807500-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6552807500-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="6552807500-15">}</span><span class="p" data-group-id="6552807500-14">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="6552807500-16">(</span><span class="n">List</span><span class="p" data-group-id="6552807500-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="6552807500-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="6552807500-17">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">92&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2167074313-1">(</span><span class="p" data-group-id="2167074313-2">[</span><span class="p" data-group-id="2167074313-3">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-4">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="2167074313-4">}</span><span class="p" data-group-id="2167074313-3">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-5">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="2167074313-6">}</span><span class="p" data-group-id="2167074313-5">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2167074313-7">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="2167074313-8">}</span><span class="p" data-group-id="2167074313-7">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="2167074313-10">}</span><span class="p" data-group-id="2167074313-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-11">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2167074313-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="2167074313-12">}</span><span class="p" data-group-id="2167074313-11">}</span><span class="p" data-group-id="2167074313-2">]</span><span class="p" data-group-id="2167074313-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2167074313-13">[</span><span class="p" data-group-id="2167074313-14">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="2167074313-15">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="2167074313-15">}</span><span class="p" data-group-id="2167074313-14">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2167074313-16">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="2167074313-17">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="2167074313-17">}</span><span class="p" data-group-id="2167074313-16">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2167074313-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="2167074313-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="2167074313-19">}</span><span class="p" data-group-id="2167074313-18">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2167074313-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="2167074313-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="2167074313-21">}</span><span class="p" data-group-id="2167074313-20">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="2167074313-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="2167074313-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2167074313-23">}</span><span class="p" data-group-id="2167074313-22">}</span><span class="p" data-group-id="2167074313-13">]</span></code></pre><p>The <code class="inline">convert_to_c</code> function is the same as before, but here it is used as a fun:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="4086941810-1">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="4086941810-1">)</span></code></pre><p>When a function defined elsewhere is used as a fun, it can be referred to as
│ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2620593319-4">(</span><span class="p" data-group-id="2620593319-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2620593319-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2620593319-6">}</span><span class="p" data-group-id="2620593319-5">}</span><span class="p" data-group-id="2620593319-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2620593319-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2620593319-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="2620593319-9">(</span><span class="p" data-group-id="2620593319-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="2620593319-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="2620593319-9">)</span><span class="p" data-group-id="2620593319-8">}</span><span class="p" data-group-id="2620593319-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2620593319-11">(</span><span class="p" data-group-id="2620593319-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2620593319-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2620593319-13">}</span><span class="p" data-group-id="2620593319-12">}</span><span class="p" data-group-id="2620593319-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2620593319-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2620593319-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2620593319-15">}</span><span class="p" data-group-id="2620593319-14">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2620593319-16">(</span><span class="n">List</span><span class="p" data-group-id="2620593319-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="2620593319-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2620593319-17">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">92&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="7380833358-1">(</span><span class="p" data-group-id="7380833358-2">[</span><span class="p" data-group-id="7380833358-3">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-4">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="7380833358-4">}</span><span class="p" data-group-id="7380833358-3">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-5">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="7380833358-6">}</span><span class="p" data-group-id="7380833358-5">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7380833358-7">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="7380833358-8">}</span><span class="p" data-group-id="7380833358-7">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-9">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-10">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="7380833358-10">}</span><span class="p" data-group-id="7380833358-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-11">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7380833358-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="7380833358-12">}</span><span class="p" data-group-id="7380833358-11">}</span><span class="p" data-group-id="7380833358-2">]</span><span class="p" data-group-id="7380833358-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7380833358-13">[</span><span class="p" data-group-id="7380833358-14">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="7380833358-15">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="7380833358-15">}</span><span class="p" data-group-id="7380833358-14">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7380833358-16">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="7380833358-17">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="7380833358-17">}</span><span class="p" data-group-id="7380833358-16">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7380833358-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="7380833358-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="7380833358-19">}</span><span class="p" data-group-id="7380833358-18">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7380833358-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="7380833358-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="7380833358-21">}</span><span class="p" data-group-id="7380833358-20">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7380833358-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="7380833358-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7380833358-23">}</span><span class="p" data-group-id="7380833358-22">}</span><span class="p" data-group-id="7380833358-13">]</span></code></pre><p>The <code class="inline">convert_to_c</code> function is the same as before, but here it is used as a fun:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="6682450862-1">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="6682450862-1">)</span></code></pre><p>When a function defined elsewhere is used as a fun, it can be referred to as
│ │ │  <code class="inline">Function/Arity</code> (remember that <code class="inline">Arity</code> = number of arguments). So in the
│ │ │  <code class="inline">map</code>-call <code class="inline">lists:map(fun convert_to_c/1, List)</code> is written. As shown,
│ │ │  <code class="inline">convert_list_to_c</code> becomes much shorter and easier to understand.</p><p>The standard module <code class="inline">lists</code> also contains a function <code class="inline">sort(Fun, List)</code> where
│ │ │  <code class="inline">Fun</code> is a fun with two arguments. This fun returns <code class="inline">true</code> if the first argument
│ │ │  is less than the second argument, or else <code class="inline">false</code>. Sorting is added to the
│ │ │ -<code class="inline">convert_list_to_c</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2104276313-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="2104276313-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">convert_list_to_c</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2732196949-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="2732196949-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2104276313-2">(</span><span class="p" data-group-id="2104276313-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2104276313-3">]</span><span class="p" data-group-id="2104276313-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2732196949-2">(</span><span class="p" data-group-id="2732196949-3">[</span><span class="ss">convert_list_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="2732196949-3">]</span><span class="p" data-group-id="2732196949-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2104276313-4">(</span><span class="p" data-group-id="2104276313-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2104276313-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2104276313-6">}</span><span class="p" data-group-id="2104276313-5">}</span><span class="p" data-group-id="2104276313-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2104276313-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2104276313-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="2104276313-9">(</span><span class="p" data-group-id="2104276313-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="2104276313-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="2104276313-9">)</span><span class="p" data-group-id="2104276313-8">}</span><span class="p" data-group-id="2104276313-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2104276313-11">(</span><span class="p" data-group-id="2104276313-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2104276313-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2104276313-13">}</span><span class="p" data-group-id="2104276313-12">}</span><span class="p" data-group-id="2104276313-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2104276313-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2104276313-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2104276313-15">}</span><span class="p" data-group-id="2104276313-14">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2104276313-16">(</span><span class="n">List</span><span class="p" data-group-id="2104276313-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">New_list</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="2104276313-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2104276313-17">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="2104276313-18">(</span><span class="nf">fun</span><span class="p" data-group-id="2104276313-19">(</span><span class="p" data-group-id="2104276313-20">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2104276313-21">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="2104276313-21">}</span><span class="p" data-group-id="2104276313-20">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2104276313-22">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2104276313-23">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="2104276313-23">}</span><span class="p" data-group-id="2104276313-22">}</span><span class="p" data-group-id="2104276313-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                       </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">New_list</span><span class="p" data-group-id="2104276313-18">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">93&gt; </span><span class="nf">c</span><span class="p" data-group-id="0934626272-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="0934626272-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0934626272-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut13</span><span class="p" data-group-id="0934626272-2">}</span><span class="gp unselectable">
│ │ │ -94&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="0934626272-3">(</span><span class="p" data-group-id="0934626272-4">[</span><span class="p" data-group-id="0934626272-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="0934626272-6">}</span><span class="p" data-group-id="0934626272-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="0934626272-8">}</span><span class="p" data-group-id="0934626272-7">}</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0934626272-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="0934626272-10">}</span><span class="p" data-group-id="0934626272-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="0934626272-12">}</span><span class="p" data-group-id="0934626272-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0934626272-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="0934626272-14">}</span><span class="p" data-group-id="0934626272-13">}</span><span class="p" data-group-id="0934626272-4">]</span><span class="p" data-group-id="0934626272-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0934626272-15">[</span><span class="p" data-group-id="0934626272-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="0934626272-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="0934626272-17">}</span><span class="p" data-group-id="0934626272-16">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0934626272-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="0934626272-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="0934626272-19">}</span><span class="p" data-group-id="0934626272-18">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0934626272-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="0934626272-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="0934626272-21">}</span><span class="p" data-group-id="0934626272-20">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0934626272-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="0934626272-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="0934626272-23">}</span><span class="p" data-group-id="0934626272-22">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0934626272-24">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="0934626272-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="0934626272-25">}</span><span class="p" data-group-id="0934626272-24">}</span><span class="p" data-group-id="0934626272-15">]</span></code></pre><p>In <code class="inline">sort</code> the fun is used:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="p" data-group-id="5470582850-1">(</span><span class="p" data-group-id="5470582850-2">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5470582850-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="5470582850-3">}</span><span class="p" data-group-id="5470582850-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5470582850-4">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5470582850-5">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="5470582850-5">}</span><span class="p" data-group-id="5470582850-4">}</span><span class="p" data-group-id="5470582850-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span></code></pre><p>Here the concept of an <em>anonymous variable</em> <code class="inline">_</code> is introduced. This is simply
│ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2732196949-4">(</span><span class="p" data-group-id="2732196949-5">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2732196949-6">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2732196949-6">}</span><span class="p" data-group-id="2732196949-5">}</span><span class="p" data-group-id="2732196949-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2732196949-7">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2732196949-8">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="nf">trunc</span><span class="p" data-group-id="2732196949-9">(</span><span class="p" data-group-id="2732196949-10">(</span><span class="n">Temp</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="mi">32</span><span class="p" data-group-id="2732196949-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="mi">5</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="2732196949-9">)</span><span class="p" data-group-id="2732196949-8">}</span><span class="p" data-group-id="2732196949-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">convert_to_c</span><span class="p" data-group-id="2732196949-11">(</span><span class="p" data-group-id="2732196949-12">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2732196949-13">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2732196949-13">}</span><span class="p" data-group-id="2732196949-12">}</span><span class="p" data-group-id="2732196949-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="2732196949-14">{</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2732196949-15">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp</span><span class="p" data-group-id="2732196949-15">}</span><span class="p" data-group-id="2732196949-14">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="2732196949-16">(</span><span class="n">List</span><span class="p" data-group-id="2732196949-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">New_list</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="2732196949-17">(</span><span class="k">fun</span><span class="w"> </span><span class="ss">convert_to_c</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="n">List</span><span class="p" data-group-id="2732196949-17">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="2732196949-18">(</span><span class="nf">fun</span><span class="p" data-group-id="2732196949-19">(</span><span class="p" data-group-id="2732196949-20">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2732196949-21">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="2732196949-21">}</span><span class="p" data-group-id="2732196949-20">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2732196949-22">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2732196949-23">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="2732196949-23">}</span><span class="p" data-group-id="2732196949-22">}</span><span class="p" data-group-id="2732196949-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                       </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">New_list</span><span class="p" data-group-id="2732196949-18">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">93&gt; </span><span class="nf">c</span><span class="p" data-group-id="3662515150-1">(</span><span class="ss">tut13</span><span class="p" data-group-id="3662515150-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3662515150-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">tut13</span><span class="p" data-group-id="3662515150-2">}</span><span class="gp unselectable">
│ │ │ +94&gt; </span><span class="nc">tut13</span><span class="p">:</span><span class="nf">convert_list_to_c</span><span class="p" data-group-id="3662515150-3">(</span><span class="p" data-group-id="3662515150-4">[</span><span class="p" data-group-id="3662515150-5">{</span><span class="ss">moscow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-6">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="3662515150-6">}</span><span class="p" data-group-id="3662515150-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-7">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-8">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">70</span><span class="p" data-group-id="3662515150-8">}</span><span class="p" data-group-id="3662515150-7">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3662515150-9">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-10">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="3662515150-10">}</span><span class="p" data-group-id="3662515150-9">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-11">{</span><span class="ss">paris</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-12">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">28</span><span class="p" data-group-id="3662515150-12">}</span><span class="p" data-group-id="3662515150-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-13">{</span><span class="ss">london</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3662515150-14">{</span><span class="ss">f</span><span class="p">,</span><span class="w"> </span><span class="mi">36</span><span class="p" data-group-id="3662515150-14">}</span><span class="p" data-group-id="3662515150-13">}</span><span class="p" data-group-id="3662515150-4">]</span><span class="p" data-group-id="3662515150-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3662515150-15">[</span><span class="p" data-group-id="3662515150-16">{</span><span class="ss">moscow</span><span class="p">,</span><span class="p" data-group-id="3662515150-17">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">10</span><span class="p" data-group-id="3662515150-17">}</span><span class="p" data-group-id="3662515150-16">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3662515150-18">{</span><span class="ss">stockholm</span><span class="p">,</span><span class="p" data-group-id="3662515150-19">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">4</span><span class="p" data-group-id="3662515150-19">}</span><span class="p" data-group-id="3662515150-18">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3662515150-20">{</span><span class="ss">paris</span><span class="p">,</span><span class="p" data-group-id="3662515150-21">{</span><span class="ss">c</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p" data-group-id="3662515150-21">}</span><span class="p" data-group-id="3662515150-20">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3662515150-22">{</span><span class="ss">london</span><span class="p">,</span><span class="p" data-group-id="3662515150-23">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3662515150-23">}</span><span class="p" data-group-id="3662515150-22">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="3662515150-24">{</span><span class="ss">cape_town</span><span class="p">,</span><span class="p" data-group-id="3662515150-25">{</span><span class="ss">c</span><span class="p">,</span><span class="mi">21</span><span class="p" data-group-id="3662515150-25">}</span><span class="p" data-group-id="3662515150-24">}</span><span class="p" data-group-id="3662515150-15">]</span></code></pre><p>In <code class="inline">sort</code> the fun is used:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="p" data-group-id="1710684010-1">(</span><span class="p" data-group-id="1710684010-2">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1710684010-3">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp1</span><span class="p" data-group-id="1710684010-3">}</span><span class="p" data-group-id="1710684010-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1710684010-4">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1710684010-5">{</span><span class="ss">c</span><span class="p">,</span><span class="w"> </span><span class="n">Temp2</span><span class="p" data-group-id="1710684010-5">}</span><span class="p" data-group-id="1710684010-4">}</span><span class="p" data-group-id="1710684010-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Temp1</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Temp2</span><span class="w"> </span><span class="k">end</span><span class="p">,</span></code></pre><p>Here the concept of an <em>anonymous variable</em> <code class="inline">_</code> is introduced. This is simply
│ │ │  shorthand for a variable that gets a value, but the value is ignored. This can
│ │ │  be used anywhere suitable, not just in funs. <code class="inline">Temp1 &lt; Temp2</code> returns <code class="inline">true</code> if
│ │ │  <code class="inline">Temp1</code> is less than <code class="inline">Temp2</code>.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/spec_proc.html
│ │ │ @@ -123,72 +123,72 @@
│ │ │    <a href="#simple-debugging" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Simple Debugging</span>
│ │ │  </h2>
│ │ │  <p>The <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html"><code class="inline">sys</code></a> module has functions for simple debugging of processes implemented
│ │ │  using behaviours. The <code class="inline">code_lock</code> example from
│ │ │ -<a href="statem.html#example">gen_statem Behaviour</a> is used to illustrate this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="2343399159-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="2343399159-1">]</span><span class="w"> </span><span class="p" data-group-id="2343399159-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="2343399159-2">]</span><span class="w"> </span><span class="p" data-group-id="2343399159-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="2343399159-3">]</span><span class="w"> </span><span class="p" data-group-id="2343399159-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="2343399159-4">]</span><span class="w"> </span><span class="p" data-group-id="2343399159-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2343399159-5">]</span><span class="w"> </span><span class="p" data-group-id="2343399159-6">[</span><span class="ss">jit</span><span class="p" data-group-id="2343399159-6">]</span><span class="w">
│ │ │ +<a href="statem.html#example">gen_statem Behaviour</a> is used to illustrate this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="2149297875-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="2149297875-1">]</span><span class="w"> </span><span class="p" data-group-id="2149297875-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="2149297875-2">]</span><span class="w"> </span><span class="p" data-group-id="2149297875-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="2149297875-3">]</span><span class="w"> </span><span class="p" data-group-id="2149297875-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="2149297875-4">]</span><span class="w"> </span><span class="p" data-group-id="2149297875-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="2149297875-5">]</span><span class="w"> </span><span class="p" data-group-id="2149297875-6">[</span><span class="ss">jit</span><span class="p" data-group-id="2149297875-6">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="2343399159-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="2343399159-8">(</span><span class="p" data-group-id="2343399159-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="2343399159-7">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="2343399159-9">(</span><span class="p" data-group-id="2343399159-10">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2343399159-10">]</span><span class="p" data-group-id="2343399159-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="2149297875-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="2149297875-8">(</span><span class="p" data-group-id="2149297875-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="2149297875-7">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="2149297875-9">(</span><span class="p" data-group-id="2149297875-10">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2149297875-10">]</span><span class="p" data-group-id="2149297875-9">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="n">Lock</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2343399159-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="2343399159-11">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="2343399159-12">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2343399159-12">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2149297875-11">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="2149297875-11">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="2149297875-12">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2149297875-12">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="2343399159-13">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2343399159-13">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="2149297875-13">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2149297875-13">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2343399159-14">(</span><span class="mi">1</span><span class="p" data-group-id="2343399159-14">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-15">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2343399159-15">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2149297875-14">(</span><span class="mi">1</span><span class="p" data-group-id="2149297875-14">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-15">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2149297875-15">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-16">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2343399159-16">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2343399159-17">(</span><span class="mi">2</span><span class="p" data-group-id="2343399159-17">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-18">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2343399159-18">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-16">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2149297875-16">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ +5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2149297875-17">(</span><span class="mi">2</span><span class="p" data-group-id="2149297875-17">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-18">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2149297875-18">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-19">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2343399159-19">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2343399159-20">(</span><span class="mi">3</span><span class="p" data-group-id="2343399159-20">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-21">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2343399159-21">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-19">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="2149297875-19">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ +6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2149297875-20">(</span><span class="mi">3</span><span class="p" data-group-id="2149297875-20">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-21">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2149297875-21">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-22">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2343399159-22">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2343399159-23">(</span><span class="mi">4</span><span class="p" data-group-id="2343399159-23">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-24">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2343399159-24">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-22">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2149297875-22">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ +7&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="2149297875-23">(</span><span class="mi">4</span><span class="p" data-group-id="2149297875-23">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-24">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2149297875-24">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="n">Unlock</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2343399159-25">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2343399159-25">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="nb">start_timer</span><span class="w"> </span><span class="p" data-group-id="2343399159-26">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10000</span><span class="p">,</span><span class="ss">lock</span><span class="p">,</span><span class="p" data-group-id="2343399159-27">[</span><span class="p" data-group-id="2343399159-27">]</span><span class="p" data-group-id="2343399159-26">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">cast</span><span class="w"> </span><span class="p" data-group-id="2149297875-25">{</span><span class="ss">button</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2149297875-25">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="nb">start_timer</span><span class="w"> </span><span class="p" data-group-id="2149297875-26">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10000</span><span class="p">,</span><span class="ss">lock</span><span class="p">,</span><span class="p" data-group-id="2149297875-27">[</span><span class="p" data-group-id="2149297875-27">]</span><span class="p" data-group-id="2149297875-26">}</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │  </span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="ss">state_timeout</span><span class="w"> </span><span class="ss">lock</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w">
│ │ │  </span><span class="n">Lock</span><span class="w">
│ │ │  </span><span class="o">*</span><span class="n">DBG</span><span class="o">*</span><span class="w"> </span><span class="ss">code_lock</span><span class="w"> </span><span class="ss">consume</span><span class="w"> </span><span class="ss">state_timeout</span><span class="w"> </span><span class="ss">lock</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">open</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">locked</span><span class="gp unselectable">
│ │ │ -8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="2343399159-28">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="2343399159-28">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2343399159-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="2343399159-30">[</span><span class="p" data-group-id="2343399159-31">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="2343399159-32">{</span><span class="p" data-group-id="2343399159-33">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2343399159-33">}</span><span class="p">,</span><span class="p" data-group-id="2343399159-34">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2343399159-34">}</span><span class="p" data-group-id="2343399159-32">}</span><span class="p" data-group-id="2343399159-31">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="2343399159-35">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="2343399159-36">{</span><span class="p" data-group-id="2343399159-37">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2343399159-37">}</span><span class="p">,</span><span class="p" data-group-id="2343399159-38">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">48</span><span class="p" data-group-id="2343399159-38">}</span><span class="p" data-group-id="2343399159-36">}</span><span class="p" data-group-id="2343399159-35">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="2343399159-39">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">4098</span><span class="p" data-group-id="2343399159-39">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="2343399159-40">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2343399159-40">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="2343399159-41">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="2343399159-41">}</span><span class="p" data-group-id="2343399159-30">]</span><span class="p" data-group-id="2343399159-29">}</span><span class="gp unselectable">
│ │ │ -9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="2343399159-42">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="2343399159-42">)</span><span class="p">.</span><span class="w">
│ │ │ +8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="2149297875-28">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="2149297875-28">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2149297875-29">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="2149297875-30">[</span><span class="p" data-group-id="2149297875-31">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="2149297875-32">{</span><span class="p" data-group-id="2149297875-33">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2149297875-33">}</span><span class="p">,</span><span class="p" data-group-id="2149297875-34">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2149297875-34">}</span><span class="p" data-group-id="2149297875-32">}</span><span class="p" data-group-id="2149297875-31">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="2149297875-35">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="2149297875-36">{</span><span class="p" data-group-id="2149297875-37">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2149297875-37">}</span><span class="p">,</span><span class="p" data-group-id="2149297875-38">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">48</span><span class="p" data-group-id="2149297875-38">}</span><span class="p" data-group-id="2149297875-36">}</span><span class="p" data-group-id="2149297875-35">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="2149297875-39">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">4098</span><span class="p" data-group-id="2149297875-39">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="2149297875-40">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2149297875-40">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="2149297875-41">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="2149297875-41">}</span><span class="p" data-group-id="2149297875-30">]</span><span class="p" data-group-id="2149297875-29">}</span><span class="gp unselectable">
│ │ │ +9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="2149297875-42">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="2149297875-42">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -10&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="2343399159-43">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="2343399159-43">)</span><span class="p">.</span><span class="w">
│ │ │ +10&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="2149297875-43">(</span><span class="ss">code_lock</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="2149297875-43">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -11&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="2343399159-44">(</span><span class="ss">code_lock</span><span class="p" data-group-id="2343399159-44">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2343399159-45">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="2343399159-46">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">gen_statem</span><span class="p" data-group-id="2343399159-46">}</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="2343399159-47">[</span><span class="p" data-group-id="2343399159-48">[</span><span class="p" data-group-id="2343399159-49">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="2343399159-50">{</span><span class="ss">code_lock</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2343399159-50">}</span><span class="p" data-group-id="2343399159-49">}</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="2343399159-51">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="2343399159-52">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ -                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="2343399159-52">]</span><span class="p" data-group-id="2343399159-51">}</span><span class="p" data-group-id="2343399159-48">]</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="2343399159-53">[</span><span class="p" data-group-id="2343399159-53">]</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="2343399159-54">[</span><span class="p" data-group-id="2343399159-55">{</span><span class="ss">header</span><span class="p">,</span><span class="s">&quot;Status for state machine code_lock&quot;</span><span class="p" data-group-id="2343399159-55">}</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="2343399159-56">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="2343399159-57">[</span><span class="p" data-group-id="2343399159-58">{</span><span class="s">&quot;Status&quot;</span><span class="p">,</span><span class="ss">running</span><span class="p" data-group-id="2343399159-58">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="2343399159-59">{</span><span class="s">&quot;Parent&quot;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="2343399159-59">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="2343399159-60">{</span><span class="s">&quot;Modules&quot;</span><span class="p">,</span><span class="p" data-group-id="2343399159-61">[</span><span class="ss">code_lock</span><span class="p" data-group-id="2343399159-61">]</span><span class="p" data-group-id="2343399159-60">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="2343399159-62">{</span><span class="s">&quot;Time-outs&quot;</span><span class="p">,</span><span class="p" data-group-id="2343399159-63">{</span><span class="mi">0</span><span class="p">,</span><span class="p" data-group-id="2343399159-64">[</span><span class="p" data-group-id="2343399159-64">]</span><span class="p" data-group-id="2343399159-63">}</span><span class="p" data-group-id="2343399159-62">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="2343399159-65">{</span><span class="s">&quot;Logged Events&quot;</span><span class="p">,</span><span class="p" data-group-id="2343399159-66">[</span><span class="p" data-group-id="2343399159-66">]</span><span class="p" data-group-id="2343399159-65">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="2343399159-67">{</span><span class="s">&quot;Postponed&quot;</span><span class="p">,</span><span class="p" data-group-id="2343399159-68">[</span><span class="p" data-group-id="2343399159-68">]</span><span class="p" data-group-id="2343399159-67">}</span><span class="p" data-group-id="2343399159-57">]</span><span class="p" data-group-id="2343399159-56">}</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="2343399159-69">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="2343399159-70">[</span><span class="p" data-group-id="2343399159-71">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="w">
│ │ │ -                  </span><span class="p" data-group-id="2343399159-72">{</span><span class="ss">locked</span><span class="p">,</span><span class="p" data-group-id="2343399159-73">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2343399159-74">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2343399159-74">]</span><span class="p">,</span><span class="w">
│ │ │ -                            </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2343399159-75">[</span><span class="p" data-group-id="2343399159-75">]</span><span class="p" data-group-id="2343399159-73">}</span><span class="p" data-group-id="2343399159-72">}</span><span class="p" data-group-id="2343399159-71">}</span><span class="p" data-group-id="2343399159-70">]</span><span class="p" data-group-id="2343399159-69">}</span><span class="p" data-group-id="2343399159-54">]</span><span class="p" data-group-id="2343399159-47">]</span><span class="p" data-group-id="2343399159-45">}</span></code></pre><h2 id="special-processes" class="section-heading">
│ │ │ +11&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="2149297875-44">(</span><span class="ss">code_lock</span><span class="p" data-group-id="2149297875-44">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2149297875-45">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2149297875-46">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">gen_statem</span><span class="p" data-group-id="2149297875-46">}</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2149297875-47">[</span><span class="p" data-group-id="2149297875-48">[</span><span class="p" data-group-id="2149297875-49">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="2149297875-50">{</span><span class="ss">code_lock</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2149297875-50">}</span><span class="p" data-group-id="2149297875-49">}</span><span class="p">,</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="2149297875-51">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="2149297875-52">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ +                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="2149297875-52">]</span><span class="p" data-group-id="2149297875-51">}</span><span class="p" data-group-id="2149297875-48">]</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="2149297875-53">[</span><span class="p" data-group-id="2149297875-53">]</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="2149297875-54">[</span><span class="p" data-group-id="2149297875-55">{</span><span class="ss">header</span><span class="p">,</span><span class="s">&quot;Status for state machine code_lock&quot;</span><span class="p" data-group-id="2149297875-55">}</span><span class="p">,</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="2149297875-56">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="2149297875-57">[</span><span class="p" data-group-id="2149297875-58">{</span><span class="s">&quot;Status&quot;</span><span class="p">,</span><span class="ss">running</span><span class="p" data-group-id="2149297875-58">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="2149297875-59">{</span><span class="s">&quot;Parent&quot;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="2149297875-59">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="2149297875-60">{</span><span class="s">&quot;Modules&quot;</span><span class="p">,</span><span class="p" data-group-id="2149297875-61">[</span><span class="ss">code_lock</span><span class="p" data-group-id="2149297875-61">]</span><span class="p" data-group-id="2149297875-60">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="2149297875-62">{</span><span class="s">&quot;Time-outs&quot;</span><span class="p">,</span><span class="p" data-group-id="2149297875-63">{</span><span class="mi">0</span><span class="p">,</span><span class="p" data-group-id="2149297875-64">[</span><span class="p" data-group-id="2149297875-64">]</span><span class="p" data-group-id="2149297875-63">}</span><span class="p" data-group-id="2149297875-62">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="2149297875-65">{</span><span class="s">&quot;Logged Events&quot;</span><span class="p">,</span><span class="p" data-group-id="2149297875-66">[</span><span class="p" data-group-id="2149297875-66">]</span><span class="p" data-group-id="2149297875-65">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="2149297875-67">{</span><span class="s">&quot;Postponed&quot;</span><span class="p">,</span><span class="p" data-group-id="2149297875-68">[</span><span class="p" data-group-id="2149297875-68">]</span><span class="p" data-group-id="2149297875-67">}</span><span class="p" data-group-id="2149297875-57">]</span><span class="p" data-group-id="2149297875-56">}</span><span class="p">,</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="2149297875-69">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="2149297875-70">[</span><span class="p" data-group-id="2149297875-71">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="w">
│ │ │ +                  </span><span class="p" data-group-id="2149297875-72">{</span><span class="ss">locked</span><span class="p">,</span><span class="p" data-group-id="2149297875-73">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2149297875-74">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2149297875-74">]</span><span class="p">,</span><span class="w">
│ │ │ +                            </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="2149297875-75">[</span><span class="p" data-group-id="2149297875-75">]</span><span class="p" data-group-id="2149297875-73">}</span><span class="p" data-group-id="2149297875-72">}</span><span class="p" data-group-id="2149297875-71">}</span><span class="p" data-group-id="2149297875-70">]</span><span class="p" data-group-id="2149297875-69">}</span><span class="p" data-group-id="2149297875-54">]</span><span class="p" data-group-id="2149297875-47">]</span><span class="p" data-group-id="2149297875-45">}</span></code></pre><h2 id="special-processes" class="section-heading">
│ │ │    <a href="#special-processes" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Special Processes</span>
│ │ │  </h2>
│ │ │  <p>This section describes how to write a process that complies to the OTP design
│ │ │  principles, without using a standard behaviour. Such a process is to:</p><ul><li>Be started in a way that makes the process fit into a supervision tree</li><li>Support the <code class="inline">sys</code> <a href="spec_proc.html#debug">debug facilities</a></li><li>Take care of <a href="spec_proc.html#msg">system messages</a>.</li></ul><p>System messages are messages with a special meaning, used in the supervision
│ │ │ @@ -198,238 +198,238 @@
│ │ │    <a href="#example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Example</span>
│ │ │  </h3>
│ │ │  <p>Here follows the simple server from
│ │ │  <a href="design_principles.html#ch1">Overview</a>,
│ │ │ -implemented using <code class="inline">sys</code> and <code class="inline">proc_lib</code> to fit into a supervision tree:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4814325089-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="4814325089-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4814325089-2">(</span><span class="p" data-group-id="4814325089-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="4814325089-3">]</span><span class="p" data-group-id="4814325089-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4814325089-4">(</span><span class="p" data-group-id="4814325089-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4814325089-5">]</span><span class="p" data-group-id="4814325089-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4814325089-6">(</span><span class="p" data-group-id="4814325089-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4814325089-7">]</span><span class="p" data-group-id="4814325089-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4814325089-8">(</span><span class="p" data-group-id="4814325089-9">[</span><span class="ss">system_continue</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">system_terminate</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w">
│ │ │ +implemented using <code class="inline">sys</code> and <code class="inline">proc_lib</code> to fit into a supervision tree:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8205133891-1">(</span><span class="ss">ch4</span><span class="p" data-group-id="8205133891-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8205133891-2">(</span><span class="p" data-group-id="8205133891-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8205133891-3">]</span><span class="p" data-group-id="8205133891-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8205133891-4">(</span><span class="p" data-group-id="8205133891-5">[</span><span class="ss">alloc</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">free</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8205133891-5">]</span><span class="p" data-group-id="8205133891-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8205133891-6">(</span><span class="p" data-group-id="8205133891-7">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8205133891-7">]</span><span class="p" data-group-id="8205133891-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8205133891-8">(</span><span class="p" data-group-id="8205133891-9">[</span><span class="ss">system_continue</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="ss">system_terminate</span><span class="p">/</span><span class="mi">4</span><span class="p">,</span><span class="w">
│ │ │           </span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="ss">system_get_state</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">system_replace_state</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="4814325089-9">]</span><span class="p" data-group-id="4814325089-8">)</span><span class="p">.</span><span class="w">
│ │ │ +         </span><span class="ss">system_get_state</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">system_replace_state</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="8205133891-9">]</span><span class="p" data-group-id="8205133891-8">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="4814325089-10">(</span><span class="p" data-group-id="4814325089-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="4814325089-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-12">[</span><span class="nf">self</span><span class="p" data-group-id="4814325089-13">(</span><span class="p" data-group-id="4814325089-13">)</span><span class="p" data-group-id="4814325089-12">]</span><span class="p" data-group-id="4814325089-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="8205133891-10">(</span><span class="p" data-group-id="8205133891-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8205133891-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-12">[</span><span class="nf">self</span><span class="p" data-group-id="8205133891-13">(</span><span class="p" data-group-id="8205133891-13">)</span><span class="p" data-group-id="8205133891-12">]</span><span class="p" data-group-id="8205133891-11">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">alloc</span><span class="p" data-group-id="4814325089-14">(</span><span class="p" data-group-id="4814325089-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4814325089-15">{</span><span class="nf">self</span><span class="p" data-group-id="4814325089-16">(</span><span class="p" data-group-id="4814325089-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="4814325089-15">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">alloc</span><span class="p" data-group-id="8205133891-14">(</span><span class="p" data-group-id="8205133891-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8205133891-15">{</span><span class="nf">self</span><span class="p" data-group-id="8205133891-16">(</span><span class="p" data-group-id="8205133891-16">)</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="8205133891-15">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4814325089-17">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="4814325089-17">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8205133891-17">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Res</span><span class="p" data-group-id="8205133891-17">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Res</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">free</span><span class="p" data-group-id="4814325089-18">(</span><span class="n">Ch</span><span class="p" data-group-id="4814325089-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4814325089-19">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4814325089-19">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">free</span><span class="p" data-group-id="8205133891-18">(</span><span class="n">Ch</span><span class="p" data-group-id="8205133891-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">ch4</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8205133891-19">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8205133891-19">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="4814325089-20">(</span><span class="n">Parent</span><span class="p" data-group-id="4814325089-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="4814325089-21">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4814325089-22">(</span><span class="p" data-group-id="4814325089-22">)</span><span class="p" data-group-id="4814325089-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="4814325089-23">(</span><span class="p" data-group-id="4814325089-23">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="4814325089-24">(</span><span class="p" data-group-id="4814325089-25">[</span><span class="p" data-group-id="4814325089-25">]</span><span class="p" data-group-id="4814325089-24">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="4814325089-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="4814325089-28">(</span><span class="p" data-group-id="4814325089-28">)</span><span class="p" data-group-id="4814325089-27">}</span><span class="p" data-group-id="4814325089-26">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="4814325089-29">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="4814325089-29">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="8205133891-20">(</span><span class="n">Parent</span><span class="p" data-group-id="8205133891-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="8205133891-21">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8205133891-22">(</span><span class="p" data-group-id="8205133891-22">)</span><span class="p" data-group-id="8205133891-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Chs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">channels</span><span class="p" data-group-id="8205133891-23">(</span><span class="p" data-group-id="8205133891-23">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="8205133891-24">(</span><span class="p" data-group-id="8205133891-25">[</span><span class="p" data-group-id="8205133891-25">]</span><span class="p" data-group-id="8205133891-24">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="8205133891-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="8205133891-28">(</span><span class="p" data-group-id="8205133891-28">)</span><span class="p" data-group-id="8205133891-27">}</span><span class="p" data-group-id="8205133891-26">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="8205133891-29">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8205133891-29">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="4814325089-30">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="4814325089-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="8205133891-30">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8205133891-30">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4814325089-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="4814325089-31">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4814325089-32">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-33">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="4814325089-33">}</span><span class="p" data-group-id="4814325089-32">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="4814325089-34">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="4814325089-34">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="4814325089-35">(</span><span class="n">Chs</span><span class="p" data-group-id="4814325089-35">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4814325089-36">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4814325089-36">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4814325089-37">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-38">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-39">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4814325089-39">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="4814325089-38">}</span><span class="p" data-group-id="4814325089-37">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="4814325089-40">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="4814325089-40">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4814325089-41">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4814325089-41">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4814325089-42">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-43">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-44">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4814325089-44">}</span><span class="p" data-group-id="4814325089-43">}</span><span class="p" data-group-id="4814325089-42">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="4814325089-45">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4814325089-45">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="4814325089-46">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="4814325089-46">)</span><span class="p">;</span><span class="w">
│ │ │ -
│ │ │ -        </span><span class="p" data-group-id="4814325089-47">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="4814325089-47">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="4814325089-48">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ -                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4814325089-48">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8205133891-31">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="8205133891-31">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="8205133891-32">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-33">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="8205133891-33">}</span><span class="p" data-group-id="8205133891-32">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="8205133891-34">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="8205133891-34">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="8205133891-35">(</span><span class="n">Chs</span><span class="p" data-group-id="8205133891-35">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8205133891-36">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8205133891-36">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="8205133891-37">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-38">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-39">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8205133891-39">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="8205133891-38">}</span><span class="p" data-group-id="8205133891-37">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="8205133891-40">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="8205133891-40">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8205133891-41">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8205133891-41">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="8205133891-42">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-43">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-44">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="8205133891-44">}</span><span class="p" data-group-id="8205133891-43">}</span><span class="p" data-group-id="8205133891-42">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="8205133891-45">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8205133891-45">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="8205133891-46">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="8205133891-46">)</span><span class="p">;</span><span class="w">
│ │ │ +
│ │ │ +        </span><span class="p" data-group-id="8205133891-47">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="8205133891-47">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="8205133891-48">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ +                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8205133891-48">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_continue</span><span class="p" data-group-id="4814325089-49">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4814325089-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="4814325089-50">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="4814325089-50">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">system_continue</span><span class="p" data-group-id="8205133891-49">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8205133891-49">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="8205133891-50">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="8205133891-50">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_terminate</span><span class="p" data-group-id="4814325089-51">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Chs</span><span class="p" data-group-id="4814325089-51">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="4814325089-52">(</span><span class="n">Reason</span><span class="p" data-group-id="4814325089-52">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">system_terminate</span><span class="p" data-group-id="8205133891-51">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Chs</span><span class="p" data-group-id="8205133891-51">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="8205133891-52">(</span><span class="n">Reason</span><span class="p" data-group-id="8205133891-52">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_get_state</span><span class="p" data-group-id="4814325089-53">(</span><span class="n">Chs</span><span class="p" data-group-id="4814325089-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4814325089-54">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4814325089-54">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">system_get_state</span><span class="p" data-group-id="8205133891-53">(</span><span class="n">Chs</span><span class="p" data-group-id="8205133891-53">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8205133891-54">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8205133891-54">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_replace_state</span><span class="p" data-group-id="4814325089-55">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4814325089-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="4814325089-56">(</span><span class="n">Chs</span><span class="p" data-group-id="4814325089-56">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4814325089-57">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="4814325089-57">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">system_replace_state</span><span class="p" data-group-id="8205133891-55">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="8205133891-55">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="8205133891-56">(</span><span class="n">Chs</span><span class="p" data-group-id="8205133891-56">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8205133891-57">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="8205133891-57">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">write_debug</span><span class="p" data-group-id="4814325089-58">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4814325089-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4814325089-59">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4814325089-60">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="4814325089-60">]</span><span class="p" data-group-id="4814325089-59">)</span><span class="p">.</span></code></pre><p id="ex">As it is not relevant to the example, the channel handling functions have been
│ │ │ +</span><span class="nf">write_debug</span><span class="p" data-group-id="8205133891-58">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="8205133891-58">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8205133891-59">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8205133891-60">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="8205133891-60">]</span><span class="p" data-group-id="8205133891-59">)</span><span class="p">.</span></code></pre><p id="ex">As it is not relevant to the example, the channel handling functions have been
│ │ │  omitted. To compile this example, the
│ │ │  <a href="design_principles.html#channels-implementation">implementation of channel handling</a>
│ │ │  needs to be added to the module.</p><p>Here is an example showing how the debugging functions in the <code class="inline">sys</code>
│ │ │  module can be used for <code class="inline">ch4</code>:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="3704483832-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="3704483832-1">]</span><span class="w"> </span><span class="p" data-group-id="3704483832-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="3704483832-2">]</span><span class="w"> </span><span class="p" data-group-id="3704483832-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3704483832-3">]</span><span class="w"> </span><span class="p" data-group-id="3704483832-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="3704483832-4">]</span><span class="w"> </span><span class="p" data-group-id="3704483832-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="3704483832-5">]</span><span class="w"> </span><span class="p" data-group-id="3704483832-6">[</span><span class="ss">jit</span><span class="p" data-group-id="3704483832-6">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">27</span><span class="w"> </span><span class="p" data-group-id="8197127322-1">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">15.0</span><span class="p" data-group-id="8197127322-1">]</span><span class="w"> </span><span class="p" data-group-id="8197127322-2">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="8197127322-2">]</span><span class="w"> </span><span class="p" data-group-id="8197127322-3">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="8197127322-3">]</span><span class="w"> </span><span class="p" data-group-id="8197127322-4">[</span><span class="nc">ds</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="8197127322-4">]</span><span class="w"> </span><span class="p" data-group-id="8197127322-5">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">1</span><span class="p" data-group-id="8197127322-5">]</span><span class="w"> </span><span class="p" data-group-id="8197127322-6">[</span><span class="ss">jit</span><span class="p" data-group-id="8197127322-6">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="3704483832-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="3704483832-8">(</span><span class="p" data-group-id="3704483832-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="3704483832-7">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3704483832-9">(</span><span class="p" data-group-id="3704483832-9">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3704483832-10">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3704483832-10">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="3704483832-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3704483832-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V15</span><span class="p">.</span><span class="mi">0</span><span class="w"> </span><span class="p" data-group-id="8197127322-7">(</span><span class="ss">press</span><span class="w"> </span><span class="n">Ctrl</span><span class="o">+</span><span class="n">G</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="nf">help</span><span class="p" data-group-id="8197127322-8">(</span><span class="p" data-group-id="8197127322-8">)</span><span class="p">.</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">help</span><span class="p" data-group-id="8197127322-7">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8197127322-9">(</span><span class="p" data-group-id="8197127322-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8197127322-10">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="8197127322-10">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="8197127322-11">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8197127322-11">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="3704483832-12">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3704483832-12">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="8197127322-12">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8197127322-12">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">alloc</span><span class="p" data-group-id="3704483832-13">(</span><span class="p" data-group-id="3704483832-13">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3704483832-14">{</span><span class="ss">in</span><span class="p">,</span><span class="ss">alloc</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3704483832-14">}</span><span class="w">
│ │ │ -</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3704483832-15">{</span><span class="ss">out</span><span class="p">,</span><span class="p" data-group-id="3704483832-16">{</span><span class="ss">ch4</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3704483832-16">}</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3704483832-15">}</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">alloc</span><span class="p" data-group-id="8197127322-13">(</span><span class="p" data-group-id="8197127322-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8197127322-14">{</span><span class="ss">in</span><span class="p">,</span><span class="ss">alloc</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="8197127322-14">}</span><span class="w">
│ │ │ +</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8197127322-15">{</span><span class="ss">out</span><span class="p">,</span><span class="p" data-group-id="8197127322-16">{</span><span class="ss">ch4</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8197127322-16">}</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="8197127322-15">}</span><span class="w">
│ │ │  </span><span class="mi">1</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">free</span><span class="p" data-group-id="3704483832-17">(</span><span class="ss">ch1</span><span class="p" data-group-id="3704483832-17">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3704483832-18">{</span><span class="ss">in</span><span class="p">,</span><span class="p" data-group-id="3704483832-19">{</span><span class="ss">free</span><span class="p">,</span><span class="ss">ch1</span><span class="p" data-group-id="3704483832-19">}</span><span class="p" data-group-id="3704483832-18">}</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">ch4</span><span class="p">:</span><span class="nf">free</span><span class="p" data-group-id="8197127322-17">(</span><span class="ss">ch1</span><span class="p" data-group-id="8197127322-17">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">ch4</span><span class="w"> </span><span class="ss">event</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8197127322-18">{</span><span class="ss">in</span><span class="p">,</span><span class="p" data-group-id="8197127322-19">{</span><span class="ss">free</span><span class="p">,</span><span class="ss">ch1</span><span class="p" data-group-id="8197127322-19">}</span><span class="p" data-group-id="8197127322-18">}</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="3704483832-20">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="3704483832-20">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3704483832-21">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="3704483832-22">[</span><span class="p" data-group-id="3704483832-23">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="3704483832-24">{</span><span class="p" data-group-id="3704483832-25">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3704483832-25">}</span><span class="p">,</span><span class="p" data-group-id="3704483832-26">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="3704483832-26">}</span><span class="p" data-group-id="3704483832-24">}</span><span class="p" data-group-id="3704483832-23">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="3704483832-27">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="3704483832-28">{</span><span class="p" data-group-id="3704483832-29">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3704483832-29">}</span><span class="p">,</span><span class="p" data-group-id="3704483832-30">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">49</span><span class="p" data-group-id="3704483832-30">}</span><span class="p" data-group-id="3704483832-28">}</span><span class="p" data-group-id="3704483832-27">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="3704483832-31">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">202</span><span class="p" data-group-id="3704483832-31">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="3704483832-32">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3704483832-32">}</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="3704483832-33">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3704483832-33">}</span><span class="p" data-group-id="3704483832-22">]</span><span class="p" data-group-id="3704483832-21">}</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="3704483832-34">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="3704483832-34">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="8197127322-20">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="nb">get</span><span class="p" data-group-id="8197127322-20">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8197127322-21">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="8197127322-22">[</span><span class="p" data-group-id="8197127322-23">{</span><span class="ss">start_time</span><span class="p">,</span><span class="p" data-group-id="8197127322-24">{</span><span class="p" data-group-id="8197127322-25">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8197127322-25">}</span><span class="p">,</span><span class="p" data-group-id="8197127322-26">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">13</span><span class="p" data-group-id="8197127322-26">}</span><span class="p" data-group-id="8197127322-24">}</span><span class="p" data-group-id="8197127322-23">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="8197127322-27">{</span><span class="ss">current_time</span><span class="p">,</span><span class="p" data-group-id="8197127322-28">{</span><span class="p" data-group-id="8197127322-29">{</span><span class="mi">2024</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8197127322-29">}</span><span class="p">,</span><span class="p" data-group-id="8197127322-30">{</span><span class="mi">8</span><span class="p">,</span><span class="mi">26</span><span class="p">,</span><span class="mi">49</span><span class="p" data-group-id="8197127322-30">}</span><span class="p" data-group-id="8197127322-28">}</span><span class="p" data-group-id="8197127322-27">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="8197127322-31">{</span><span class="ss">reductions</span><span class="p">,</span><span class="mi">202</span><span class="p" data-group-id="8197127322-31">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="8197127322-32">{</span><span class="ss">messages_in</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8197127322-32">}</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="8197127322-33">{</span><span class="ss">messages_out</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8197127322-33">}</span><span class="p" data-group-id="8197127322-22">]</span><span class="p" data-group-id="8197127322-21">}</span><span class="gp unselectable">
│ │ │ +7&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="8197127322-34">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="8197127322-34">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="3704483832-35">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="3704483832-35">)</span><span class="p">.</span><span class="w">
│ │ │ +8&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="8197127322-35">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">false</span><span class="p" data-group-id="8197127322-35">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="3704483832-36">(</span><span class="ss">ch4</span><span class="p" data-group-id="3704483832-36">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3704483832-37">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="3704483832-38">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">ch4</span><span class="p" data-group-id="3704483832-38">}</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="3704483832-39">[</span><span class="p" data-group-id="3704483832-40">[</span><span class="p" data-group-id="3704483832-41">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="3704483832-42">{</span><span class="ss">ch4</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3704483832-42">}</span><span class="p" data-group-id="3704483832-41">}</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="3704483832-43">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="3704483832-44">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ -                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3704483832-44">]</span><span class="p" data-group-id="3704483832-43">}</span><span class="p" data-group-id="3704483832-40">]</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="3704483832-45">[</span><span class="p" data-group-id="3704483832-45">]</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="3704483832-46">{</span><span class="p" data-group-id="3704483832-47">[</span><span class="mi">1</span><span class="p" data-group-id="3704483832-47">]</span><span class="p">,</span><span class="p" data-group-id="3704483832-48">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">18</span><span class="p">,</span><span class="mi">19</span><span class="p">|</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3704483832-48">]</span><span class="p" data-group-id="3704483832-46">}</span><span class="p" data-group-id="3704483832-39">]</span><span class="p" data-group-id="3704483832-37">}</span></code></pre><h3 id="starting-the-process" class="section-heading">
│ │ │ +9&gt; </span><span class="nc">sys</span><span class="p">:</span><span class="nf">get_status</span><span class="p" data-group-id="8197127322-36">(</span><span class="ss">ch4</span><span class="p" data-group-id="8197127322-36">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8197127322-37">{</span><span class="ss">status</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.90</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8197127322-38">{</span><span class="ss">module</span><span class="p">,</span><span class="ss">ch4</span><span class="p" data-group-id="8197127322-38">}</span><span class="p">,</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8197127322-39">[</span><span class="p" data-group-id="8197127322-40">[</span><span class="p" data-group-id="8197127322-41">{</span><span class="ss">&#39;$initial_call&#39;</span><span class="p">,</span><span class="p" data-group-id="8197127322-42">{</span><span class="ss">ch4</span><span class="p">,</span><span class="ss">init</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8197127322-42">}</span><span class="p" data-group-id="8197127322-41">}</span><span class="p">,</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="8197127322-43">{</span><span class="ss">&#39;$ancestors&#39;</span><span class="p">,</span><span class="p" data-group-id="8197127322-44">[</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.87</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.70</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.65</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.69</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ +                         </span><span class="o">&lt;</span><span class="mf">0.64</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">kernel_sup</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.47</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="8197127322-44">]</span><span class="p" data-group-id="8197127322-43">}</span><span class="p" data-group-id="8197127322-40">]</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="ss">running</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.88</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="p" data-group-id="8197127322-45">[</span><span class="p" data-group-id="8197127322-45">]</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="8197127322-46">{</span><span class="p" data-group-id="8197127322-47">[</span><span class="mi">1</span><span class="p" data-group-id="8197127322-47">]</span><span class="p">,</span><span class="p" data-group-id="8197127322-48">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">11</span><span class="p">,</span><span class="mi">12</span><span class="p">,</span><span class="mi">13</span><span class="p">,</span><span class="mi">14</span><span class="p">,</span><span class="mi">15</span><span class="p">,</span><span class="mi">16</span><span class="p">,</span><span class="mi">17</span><span class="p">,</span><span class="mi">18</span><span class="p">,</span><span class="mi">19</span><span class="p">|</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="8197127322-48">]</span><span class="p" data-group-id="8197127322-46">}</span><span class="p" data-group-id="8197127322-39">]</span><span class="p" data-group-id="8197127322-37">}</span></code></pre><h3 id="starting-the-process" class="section-heading">
│ │ │    <a href="#starting-the-process" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting the Process</span>
│ │ │  </h3>
│ │ │  <p>A function in the <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html"><code class="inline">proc_lib</code></a> module is to be used to start the process. Several
│ │ │  functions are available, for example,
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#spawn_link/4"><code class="inline">proc_lib:spawn_link/3,4</code></a>
│ │ │  for asynchronous start and
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#start_link/5"><code class="inline">proc_lib:start_link/3,4,5</code></a> for synchronous start.</p><p>Information necessary for a process within a supervision tree, such as
│ │ │  details on ancestors and the initial call, is stored when a process
│ │ │  is started through one of these functions.</p><p>If the process terminates with a reason other than <code class="inline">normal</code> or <code class="inline">shutdown</code>, a
│ │ │  crash report is generated. For more information about the crash report, see
│ │ │  <a href="../../lib/kernel-10.2.7.2/doc/html/logger_chapter.html">Logging</a> in Kernel User's Guide.</p><p>In the example, synchronous start is used. The process starts by calling
│ │ │ -<code class="inline">ch4:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="1824745754-1">(</span><span class="p" data-group-id="1824745754-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1824745754-2">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1824745754-3">[</span><span class="nf">self</span><span class="p" data-group-id="1824745754-4">(</span><span class="p" data-group-id="1824745754-4">)</span><span class="p" data-group-id="1824745754-3">]</span><span class="p" data-group-id="1824745754-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch4:start_link/0</code> calls <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a>, which takes a module
│ │ │ +<code class="inline">ch4:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="1803214298-1">(</span><span class="p" data-group-id="1803214298-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1803214298-2">(</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1803214298-3">[</span><span class="nf">self</span><span class="p" data-group-id="1803214298-4">(</span><span class="p" data-group-id="1803214298-4">)</span><span class="p" data-group-id="1803214298-3">]</span><span class="p" data-group-id="1803214298-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch4:start_link/0</code> calls <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a>, which takes a module
│ │ │  name, a function name, and an argument list as arguments. It then
│ │ │  spawns a new process and establishes a link. The new process starts
│ │ │  by executing the given function, here <code class="inline">ch4:init(Pid)</code>, where <code class="inline">Pid</code> is
│ │ │  the pid of the parent process (obtained by the call to
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#self/0"><code class="inline">self()</code></a> in the call to <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a>).</p><p>All initialization, including name registration, is done in <code class="inline">init/1</code>. The new
│ │ │ -process has to acknowledge that it has been started to the parent:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="6747715861-1">(</span><span class="n">Parent</span><span class="p" data-group-id="6747715861-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +process has to acknowledge that it has been started to the parent:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="3537724869-1">(</span><span class="n">Parent</span><span class="p" data-group-id="3537724869-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="6747715861-2">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6747715861-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6747715861-4">(</span><span class="p" data-group-id="6747715861-4">)</span><span class="p" data-group-id="6747715861-3">}</span><span class="p" data-group-id="6747715861-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="6747715861-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6747715861-5">)</span><span class="p">.</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a> is synchronous and does not return until
│ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="3537724869-2">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3537724869-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3537724869-4">(</span><span class="p" data-group-id="3537724869-4">)</span><span class="p" data-group-id="3537724869-3">}</span><span class="p" data-group-id="3537724869-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="3537724869-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3537724869-5">)</span><span class="p">.</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#start_link/3"><code class="inline">proc_lib:start_link/3</code></a> is synchronous and does not return until
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#init_ack/2"><code class="inline">proc_lib:init_ack/1,2</code></a> or
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#init_fail/3"><code class="inline">proc_lib:init_fail/2,3</code></a> has been called,
│ │ │  or the process has exited.</p><p><a href="" id="debug"></a></p><h3 id="debugging" class="section-heading">
│ │ │    <a href="#debugging" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Debugging</span>
│ │ │  </h3>
│ │ │  <p>To support the debug facilities in <code class="inline">sys</code>, a <em>debug structure</em> is needed. The
│ │ │ -<code class="inline">Deb</code> term is initialized using <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="9980174697-1">(</span><span class="n">Parent</span><span class="p" data-group-id="9980174697-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +<code class="inline">Deb</code> term is initialized using <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="2793027404-1">(</span><span class="n">Parent</span><span class="p" data-group-id="2793027404-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="9980174697-2">(</span><span class="p" data-group-id="9980174697-3">[</span><span class="p" data-group-id="9980174697-3">]</span><span class="p" data-group-id="9980174697-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Deb</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="2793027404-2">(</span><span class="p" data-group-id="2793027404-3">[</span><span class="p" data-group-id="2793027404-3">]</span><span class="p" data-group-id="2793027404-2">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="9980174697-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="9980174697-4">)</span><span class="p">.</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a> takes a list of options. Given an empty list as in this
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="2793027404-4">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="2793027404-4">)</span><span class="p">.</span></code></pre><p><a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a> takes a list of options. Given an empty list as in this
│ │ │  example means that debugging is initially disabled. For information about the
│ │ │  possible options, see <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html"><code class="inline">sys</code></a> in STDLIB.</p><p>For each <em>system event</em> to be logged or traced, the following function
│ │ │ -is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4685714234-1">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Func</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="4685714234-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Deb1</span></code></pre><p>The arguments have the follow meaning:</p><ul><li><code class="inline">Deb</code> is the debug structure as returned from <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>.</li><li><code class="inline">Func</code> is a fun specifying a (user-defined) function used to format trace
│ │ │ +is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="1781365418-1">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Func</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="1781365418-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Deb1</span></code></pre><p>The arguments have the follow meaning:</p><ul><li><code class="inline">Deb</code> is the debug structure as returned from <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#debug_options/1"><code class="inline">sys:debug_options/1</code></a>.</li><li><code class="inline">Func</code> is a fun specifying a (user-defined) function used to format trace
│ │ │  output. For each system event, the format function is called as
│ │ │  <code class="inline">Func(Dev, Event, Info)</code>, where:<ul><li><code class="inline">Dev</code> is the I/O device to which the output is to be printed. See <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html"><code class="inline">io</code></a>
│ │ │  in STDLIB.</li><li><code class="inline">Event</code> and <code class="inline">Info</code> are passed as-is from the call to <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#handle_debug/4"><code class="inline">sys:handle_debug/4</code></a>.</li></ul></li><li><code class="inline">Info</code> is used to pass more information to <code class="inline">Func</code>. It can be any term, and it
│ │ │  is passed as-is.</li><li><code class="inline">Event</code> is the system event. It is up to the user to define what a system
│ │ │  event is and how it is to be represented. Typically, at least incoming and
│ │ │  outgoing messages are considered system events and represented by the tuples
│ │ │  <code class="inline">{in,Msg[,From]}</code> and <code class="inline">{out,Msg,To[,State]}</code>, respectively.</li></ul><p><a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#handle_debug/4"><code class="inline">sys:handle_debug/4</code></a> returns an updated debug structure <code class="inline">Deb1</code>.</p><p>In the example, <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#handle_debug/4"><code class="inline">sys:handle_debug/4</code></a> is called for each incoming and
│ │ │  outgoing message. The format function <code class="inline">Func</code> is the function
│ │ │ -<code class="inline">ch4:write_debug/3</code>, which prints the message using <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/3"><code class="inline">io:format/3</code></a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="4669561791-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="4669561791-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +<code class="inline">ch4:write_debug/3</code>, which prints the message using <a href="../../lib/stdlib-6.2.2.2/doc/html/io.html#format/3"><code class="inline">io:format/3</code></a>.</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="4779985891-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="4779985891-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4669561791-2">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="4669561791-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4669561791-3">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4669561791-4">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="4669561791-4">}</span><span class="p" data-group-id="4669561791-3">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="4669561791-5">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="4669561791-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="4669561791-6">(</span><span class="n">Chs</span><span class="p" data-group-id="4669561791-6">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4669561791-7">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4669561791-7">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4669561791-8">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4669561791-9">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4669561791-10">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4669561791-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="4669561791-9">}</span><span class="p" data-group-id="4669561791-8">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="4669561791-11">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="4669561791-11">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4669561791-12">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4669561791-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4669561791-13">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4669561791-14">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4669561791-15">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4669561791-15">}</span><span class="p" data-group-id="4669561791-14">}</span><span class="p" data-group-id="4669561791-13">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="4669561791-16">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4669561791-16">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">loop</span><span class="p" data-group-id="4669561791-17">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="4669561791-17">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="4779985891-2">{</span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p" data-group-id="4779985891-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4779985891-3">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4779985891-4">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="ss">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="4779985891-4">}</span><span class="p" data-group-id="4779985891-3">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="4779985891-5">{</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs2</span><span class="p" data-group-id="4779985891-5">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alloc</span><span class="p" data-group-id="4779985891-6">(</span><span class="n">Chs</span><span class="p" data-group-id="4779985891-6">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="4779985891-7">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4779985891-7">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">Deb3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4779985891-8">(</span><span class="n">Deb2</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4779985891-9">{</span><span class="ss">out</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4779985891-10">{</span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4779985891-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p" data-group-id="4779985891-9">}</span><span class="p" data-group-id="4779985891-8">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="4779985891-11">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb3</span><span class="p" data-group-id="4779985891-11">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="4779985891-12">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4779985891-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Deb2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_debug</span><span class="p" data-group-id="4779985891-13">(</span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="nc">ch4</span><span class="p">:</span><span class="ss">write_debug</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4779985891-14">{</span><span class="ss">in</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4779985891-15">{</span><span class="ss">free</span><span class="p">,</span><span class="w"> </span><span class="n">Ch</span><span class="p" data-group-id="4779985891-15">}</span><span class="p" data-group-id="4779985891-14">}</span><span class="p" data-group-id="4779985891-13">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">Chs2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">free</span><span class="p" data-group-id="4779985891-16">(</span><span class="n">Ch</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4779985891-16">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">loop</span><span class="p" data-group-id="4779985891-17">(</span><span class="n">Chs2</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb2</span><span class="p" data-group-id="4779985891-17">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">write_debug</span><span class="p" data-group-id="4669561791-18">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4669561791-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4669561791-19">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4669561791-20">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="4669561791-20">]</span><span class="p" data-group-id="4669561791-19">)</span><span class="p">.</span></code></pre><p><a href="" id="msg"></a></p><h3 id="handling-system-messages" class="section-heading">
│ │ │ +</span><span class="nf">write_debug</span><span class="p" data-group-id="4779985891-18">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p" data-group-id="4779985891-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4779985891-19">(</span><span class="n">Dev</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;</span><span class="si">~p</span><span class="s"> event = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4779985891-20">[</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="4779985891-20">]</span><span class="p" data-group-id="4779985891-19">)</span><span class="p">.</span></code></pre><p><a href="" id="msg"></a></p><h3 id="handling-system-messages" class="section-heading">
│ │ │    <a href="#handling-system-messages" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Handling System Messages</span>
│ │ │  </h3>
│ │ │  <p><em>System messages</em> are received as:</p><pre><code class="text">{system, From, Request}</code></pre><p>The content and meaning of these messages are not to be interpreted by the
│ │ │ -process. Instead the following function is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="1322597075-1">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="1322597075-1">)</span></code></pre><p>The arguments have the following meaning:</p><ul><li><code class="inline">Request</code> and <code class="inline">From</code> from the received system message are to be
│ │ │ +process. Instead the following function is to be called:</p><pre><code class="makeup erlang" translate="no"><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="4075542385-1">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4075542385-1">)</span></code></pre><p>The arguments have the following meaning:</p><ul><li><code class="inline">Request</code> and <code class="inline">From</code> from the received system message are to be
│ │ │  passed as-is to the call to <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg/6</code></a>.</li><li><code class="inline">Parent</code> is the pid of the parent process.</li><li><code class="inline">Module</code> is the name of the module implementing the speciall process.</li><li><code class="inline">Deb</code> is the debug structure.</li><li><code class="inline">State</code> is a term describing the internal state and is passed on to
│ │ │  <code class="inline">Module:system_continue/3</code>, <code class="inline">Module:system_terminate/4</code>/
│ │ │  <code class="inline">Module:system_get_state/1</code>, and <code class="inline">Module:system_replace_state/2</code>.</li></ul><p><a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg/6</code></a> does not return. It handles the system
│ │ │  message and <em>eventually</em> calls either of the following functions:</p><ul><li><p><code class="inline">Module:system_continue(Parent, Deb, State)</code> - if process execution is to
│ │ │  continue.</p></li><li><p><code class="inline">Module:system_terminate(Reason, Parent, Deb, State)</code> - if the
│ │ │  process is to terminate.</p></li></ul><p>While handling the system message, <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#handle_system_msg/6"><code class="inline">sys:handle_system_msg/6</code></a> can call
│ │ │  one of the following functions:</p><ul><li><p><code class="inline">Module:system_get_state(State)</code> - if the process is to return its state.</p></li><li><p><code class="inline">Module:system_replace_state(StateFun, State)</code> - if the process is
│ │ │  to replace its state using the fun <code class="inline">StateFun</code> fun. See <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#replace_state/3"><code class="inline">sys:replace_state/3</code></a>
│ │ │  for more information.</p></li><li><p><code class="inline">system_code_change(Misc, Module, OldVsn, Extra)</code> - if the process is to
│ │ │  perform a code change.</p></li></ul><p>A process in a supervision tree is expected to terminate with the same reason as
│ │ │ -its parent.</p><p>In the example, system messages are handed by the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="2117165197-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="2117165197-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +its parent.</p><p>In the example, system messages are handed by the following code:</p><pre><code class="makeup erlang" translate="no"><span class="nf">loop</span><span class="p" data-group-id="4543978429-1">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="4543978429-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -        </span><span class="p" data-group-id="2117165197-2">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="2117165197-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="2117165197-3">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ -                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2117165197-3">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="4543978429-2">{</span><span class="ss">system</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="4543978429-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">sys</span><span class="p">:</span><span class="nf">handle_system_msg</span><span class="p" data-group-id="4543978429-3">(</span><span class="n">Request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w">
│ │ │ +                                  </span><span class="ss">ch4</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4543978429-3">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_continue</span><span class="p" data-group-id="2117165197-4">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2117165197-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="2117165197-5">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="2117165197-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">system_continue</span><span class="p" data-group-id="4543978429-4">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4543978429-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="4543978429-5">(</span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p" data-group-id="4543978429-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_terminate</span><span class="p" data-group-id="2117165197-6">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2117165197-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">exit</span><span class="p" data-group-id="2117165197-7">(</span><span class="n">Reason</span><span class="p" data-group-id="2117165197-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">system_terminate</span><span class="p" data-group-id="4543978429-6">(</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4543978429-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">exit</span><span class="p" data-group-id="4543978429-7">(</span><span class="n">Reason</span><span class="p" data-group-id="4543978429-7">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_get_state</span><span class="p" data-group-id="2117165197-8">(</span><span class="n">Chs</span><span class="p" data-group-id="2117165197-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2117165197-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2117165197-9">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">system_get_state</span><span class="p" data-group-id="4543978429-8">(</span><span class="n">Chs</span><span class="p" data-group-id="4543978429-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4543978429-9">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4543978429-9">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">system_replace_state</span><span class="p" data-group-id="2117165197-10">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="2117165197-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="2117165197-11">(</span><span class="n">Chs</span><span class="p" data-group-id="2117165197-11">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2117165197-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="2117165197-12">}</span><span class="p">.</span></code></pre><p>If a special process is configured to trap exits, it must take notice
│ │ │ +</span><span class="nf">system_replace_state</span><span class="p" data-group-id="4543978429-10">(</span><span class="n">StateFun</span><span class="p">,</span><span class="w"> </span><span class="n">Chs</span><span class="p" data-group-id="4543978429-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">NChs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">StateFun</span><span class="p" data-group-id="4543978429-11">(</span><span class="n">Chs</span><span class="p" data-group-id="4543978429-11">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4543978429-12">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p">,</span><span class="w"> </span><span class="n">NChs</span><span class="p" data-group-id="4543978429-12">}</span><span class="p">.</span></code></pre><p>If a special process is configured to trap exits, it must take notice
│ │ │  of 'EXIT' messages from its parent process and terminate using the
│ │ │ -same exit reason once the parent process has terminated.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="9495690216-1">(</span><span class="n">Parent</span><span class="p" data-group-id="9495690216-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +same exit reason once the parent process has terminated.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1877700939-1">(</span><span class="n">Parent</span><span class="p" data-group-id="1877700939-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="9495690216-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="9495690216-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="1877700939-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="1877700939-2">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="9495690216-3">(</span><span class="n">Parent</span><span class="p" data-group-id="9495690216-3">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="1877700939-3">(</span><span class="n">Parent</span><span class="p" data-group-id="1877700939-3">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">loop</span><span class="p" data-group-id="9495690216-4">(</span><span class="n">Parent</span><span class="p" data-group-id="9495690216-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">loop</span><span class="p" data-group-id="1877700939-4">(</span><span class="n">Parent</span><span class="p" data-group-id="1877700939-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="9495690216-5">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="9495690216-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1877700939-5">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="1877700939-5">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="c1">%% Clean up here, if needed.</span><span class="w">
│ │ │ -            </span><span class="nf">exit</span><span class="p" data-group-id="9495690216-6">(</span><span class="n">Reason</span><span class="p" data-group-id="9495690216-6">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="nf">exit</span><span class="p" data-group-id="1877700939-6">(</span><span class="n">Reason</span><span class="p" data-group-id="1877700939-6">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><h2 id="user-defined-behaviours" class="section-heading">
│ │ │    <a href="#user-defined-behaviours" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">User-Defined Behaviours</span>
│ │ │  </h2>
│ │ │ @@ -448,71 +448,71 @@
│ │ │  function. Note that the <code class="inline">-optional_callbacks</code> attribute is to be used together
│ │ │  with the <code class="inline">-callback</code> attribute; it cannot be combined with the
│ │ │  <code class="inline">behaviour_info()</code> function described below.</p><p>Tools that need to know about optional callback functions can call
│ │ │  <code class="inline">Behaviour:behaviour_info(optional_callbacks)</code> to get a list of all optional
│ │ │  callback functions.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>We recommend using the <code class="inline">-callback</code> attribute rather than the
│ │ │  <code class="inline">behaviour_info()</code> function. The reason is that the extra type information can
│ │ │  be used by tools to produce documentation or find discrepancies.</p></section><p>As an alternative to the <code class="inline">-callback</code> and <code class="inline">-optional_callbacks</code> attributes you
│ │ │ -may directly implement and export <code class="inline">behaviour_info()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="7889845227-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="7889845227-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7889845227-2">[</span><span class="p" data-group-id="7889845227-3">{</span><span class="n">Name1</span><span class="p">,</span><span class="w"> </span><span class="n">Arity1</span><span class="p" data-group-id="7889845227-3">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="p" data-group-id="7889845227-4">{</span><span class="n">NameN</span><span class="p">,</span><span class="w"> </span><span class="n">ArityN</span><span class="p" data-group-id="7889845227-4">}</span><span class="p" data-group-id="7889845227-2">]</span><span class="p">.</span></code></pre><p>where each <code class="inline">{Name, Arity}</code> specifies the name and arity of a callback function.
│ │ │ +may directly implement and export <code class="inline">behaviour_info()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">behaviour_info</span><span class="p" data-group-id="5822130052-1">(</span><span class="ss">callbacks</span><span class="p" data-group-id="5822130052-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5822130052-2">[</span><span class="p" data-group-id="5822130052-3">{</span><span class="n">Name1</span><span class="p">,</span><span class="w"> </span><span class="n">Arity1</span><span class="p" data-group-id="5822130052-3">}</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="p" data-group-id="5822130052-4">{</span><span class="n">NameN</span><span class="p">,</span><span class="w"> </span><span class="n">ArityN</span><span class="p" data-group-id="5822130052-4">}</span><span class="p" data-group-id="5822130052-2">]</span><span class="p">.</span></code></pre><p>where each <code class="inline">{Name, Arity}</code> specifies the name and arity of a callback function.
│ │ │  This function is otherwise automatically generated by the compiler using the
│ │ │  <code class="inline">-callback</code> attributes.</p><p>When the compiler encounters the module attribute <code class="inline">-behaviour(Behaviour).</code> in a
│ │ │  module <code class="inline">Mod</code>, it calls <code class="inline">Behaviour:behaviour_info(callbacks)</code> and compares the
│ │ │  result with the set of functions actually exported from <code class="inline">Mod</code>, and issues a
│ │ │  warning if any callback function is missing.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">%% User-defined behaviour module</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3694494009-1">(</span><span class="ss">simple_server</span><span class="p" data-group-id="3694494009-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3694494009-2">(</span><span class="p" data-group-id="3694494009-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3694494009-3">]</span><span class="p" data-group-id="3694494009-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0730095089-1">(</span><span class="ss">simple_server</span><span class="p" data-group-id="0730095089-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0730095089-2">(</span><span class="p" data-group-id="0730095089-3">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0730095089-3">]</span><span class="p" data-group-id="0730095089-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">init</span><span class="p" data-group-id="3694494009-4">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3694494009-5">(</span><span class="p" data-group-id="3694494009-5">)</span><span class="p" data-group-id="3694494009-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="3694494009-6">(</span><span class="n">Req</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3694494009-7">(</span><span class="p" data-group-id="3694494009-7">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3694494009-8">(</span><span class="p" data-group-id="3694494009-8">)</span><span class="p" data-group-id="3694494009-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3694494009-9">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3694494009-10">(</span><span class="p" data-group-id="3694494009-10">)</span><span class="p" data-group-id="3694494009-9">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">terminate</span><span class="p" data-group-id="3694494009-11">(</span><span class="p" data-group-id="3694494009-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">format_state</span><span class="p" data-group-id="3694494009-12">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3694494009-13">(</span><span class="p" data-group-id="3694494009-13">)</span><span class="p" data-group-id="3694494009-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3694494009-14">(</span><span class="p" data-group-id="3694494009-14">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">init</span><span class="p" data-group-id="0730095089-4">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0730095089-5">(</span><span class="p" data-group-id="0730095089-5">)</span><span class="p" data-group-id="0730095089-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="0730095089-6">(</span><span class="n">Req</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0730095089-7">(</span><span class="p" data-group-id="0730095089-7">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0730095089-8">(</span><span class="p" data-group-id="0730095089-8">)</span><span class="p" data-group-id="0730095089-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0730095089-9">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Reply</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0730095089-10">(</span><span class="p" data-group-id="0730095089-10">)</span><span class="p" data-group-id="0730095089-9">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">terminate</span><span class="p" data-group-id="0730095089-11">(</span><span class="p" data-group-id="0730095089-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">&#39;ok&#39;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">callback</span><span class="w"> </span><span class="nf">format_state</span><span class="p" data-group-id="0730095089-12">(</span><span class="n">State</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0730095089-13">(</span><span class="p" data-group-id="0730095089-13">)</span><span class="p" data-group-id="0730095089-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="0730095089-14">(</span><span class="p" data-group-id="0730095089-14">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">optional_callbacks</span><span class="p" data-group-id="3694494009-15">(</span><span class="p" data-group-id="3694494009-16">[</span><span class="ss">format_state</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3694494009-16">]</span><span class="p" data-group-id="3694494009-15">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">optional_callbacks</span><span class="p" data-group-id="0730095089-15">(</span><span class="p" data-group-id="0730095089-16">[</span><span class="ss">format_state</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0730095089-16">]</span><span class="p" data-group-id="0730095089-15">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% Alternatively you may define:</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │  </span><span class="c1">%% -export([behaviour_info/1]).</span><span class="w">
│ │ │  </span><span class="c1">%% behaviour_info(callbacks) -&gt;</span><span class="w">
│ │ │  </span><span class="c1">%%     [{init,1},</span><span class="w">
│ │ │  </span><span class="c1">%%      {handle_req,2},</span><span class="w">
│ │ │  </span><span class="c1">%%      {terminate,0}].</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="3694494009-17">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="3694494009-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="3694494009-18">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3694494009-19">[</span><span class="nf">self</span><span class="p" data-group-id="3694494009-20">(</span><span class="p" data-group-id="3694494009-20">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="3694494009-19">]</span><span class="p" data-group-id="3694494009-18">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="0730095089-17">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="0730095089-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0730095089-18">(</span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0730095089-19">[</span><span class="nf">self</span><span class="p" data-group-id="0730095089-20">(</span><span class="p" data-group-id="0730095089-20">)</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="0730095089-19">]</span><span class="p" data-group-id="0730095089-18">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="3694494009-21">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="3694494009-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">register</span><span class="p" data-group-id="3694494009-22">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3694494009-23">(</span><span class="p" data-group-id="3694494009-23">)</span><span class="p" data-group-id="3694494009-22">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="0730095089-21">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p" data-group-id="0730095089-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">register</span><span class="p" data-group-id="0730095089-22">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0730095089-23">(</span><span class="p" data-group-id="0730095089-23">)</span><span class="p" data-group-id="0730095089-22">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Dbg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="3694494009-24">(</span><span class="p" data-group-id="3694494009-25">[</span><span class="p" data-group-id="3694494009-25">]</span><span class="p" data-group-id="3694494009-24">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="3694494009-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3694494009-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="3694494009-28">(</span><span class="p" data-group-id="3694494009-28">)</span><span class="p" data-group-id="3694494009-27">}</span><span class="p" data-group-id="3694494009-26">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">loop</span><span class="p" data-group-id="3694494009-29">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="3694494009-29">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="n">Dbg</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">sys</span><span class="p">:</span><span class="nf">debug_options</span><span class="p" data-group-id="0730095089-24">(</span><span class="p" data-group-id="0730095089-25">[</span><span class="p" data-group-id="0730095089-25">]</span><span class="p" data-group-id="0730095089-24">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">proc_lib</span><span class="p">:</span><span class="nf">init_ack</span><span class="p" data-group-id="0730095089-26">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0730095089-27">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0730095089-28">(</span><span class="p" data-group-id="0730095089-28">)</span><span class="p" data-group-id="0730095089-27">}</span><span class="p" data-group-id="0730095089-26">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">loop</span><span class="p" data-group-id="0730095089-29">(</span><span class="n">Parent</span><span class="p">,</span><span class="w"> </span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Deb</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="0730095089-29">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>In a callback module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0339180323-1">(</span><span class="ss">db</span><span class="p" data-group-id="0339180323-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="0339180323-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="0339180323-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>In a callback module:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1610117200-1">(</span><span class="ss">db</span><span class="p" data-group-id="1610117200-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="1610117200-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="1610117200-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0339180323-3">(</span><span class="p" data-group-id="0339180323-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0339180323-4">]</span><span class="p" data-group-id="0339180323-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1610117200-3">(</span><span class="p" data-group-id="1610117200-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1610117200-4">]</span><span class="p" data-group-id="1610117200-3">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The contracts specified with <code class="inline">-callback</code> attributes in behaviour modules can be
│ │ │  further refined by adding <code class="inline">-spec</code> attributes in callback modules. This can be
│ │ │  useful as <code class="inline">-callback</code> contracts are usually generic. The same callback module
│ │ │ -with contracts for the callbacks:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="2340931972-1">(</span><span class="ss">db</span><span class="p" data-group-id="2340931972-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="2340931972-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="2340931972-2">)</span><span class="p">.</span><span class="w">
│ │ │ +with contracts for the callbacks:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3705657993-1">(</span><span class="ss">db</span><span class="p" data-group-id="3705657993-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="3705657993-2">(</span><span class="ss">simple_server</span><span class="p" data-group-id="3705657993-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2340931972-3">(</span><span class="p" data-group-id="2340931972-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2340931972-4">]</span><span class="p" data-group-id="2340931972-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3705657993-3">(</span><span class="p" data-group-id="3705657993-4">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">handle_req</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">terminate</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="3705657993-4">]</span><span class="p" data-group-id="3705657993-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="2340931972-5">(</span><span class="ss">state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2340931972-6">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="2340931972-7">[</span><span class="nf">atom</span><span class="p" data-group-id="2340931972-8">(</span><span class="p" data-group-id="2340931972-8">)</span><span class="p" data-group-id="2340931972-7">]</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="2340931972-9">(</span><span class="p" data-group-id="2340931972-9">)</span><span class="p" data-group-id="2340931972-6">}</span><span class="p" data-group-id="2340931972-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="3705657993-5">(</span><span class="ss">state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3705657993-6">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3705657993-7">[</span><span class="nf">atom</span><span class="p" data-group-id="3705657993-8">(</span><span class="p" data-group-id="3705657993-8">)</span><span class="p" data-group-id="3705657993-7">]</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="3705657993-9">(</span><span class="p" data-group-id="3705657993-9">)</span><span class="p" data-group-id="3705657993-6">}</span><span class="p" data-group-id="3705657993-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="2340931972-10">(</span><span class="p" data-group-id="2340931972-10">)</span><span class="w">   </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="2340931972-11">{</span><span class="p" data-group-id="2340931972-11">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">request</span><span class="p" data-group-id="2340931972-12">(</span><span class="p" data-group-id="2340931972-12">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="2340931972-13">{</span><span class="ss">&#39;store&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="2340931972-14">(</span><span class="p" data-group-id="2340931972-14">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="2340931972-15">(</span><span class="p" data-group-id="2340931972-15">)</span><span class="p" data-group-id="2340931972-13">}</span><span class="p">;</span><span class="w">
│ │ │ -                   </span><span class="p" data-group-id="2340931972-16">{</span><span class="ss">&#39;lookup&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="2340931972-17">(</span><span class="p" data-group-id="2340931972-17">)</span><span class="p" data-group-id="2340931972-16">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="3705657993-10">(</span><span class="p" data-group-id="3705657993-10">)</span><span class="w">   </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">state</span><span class="p" data-group-id="3705657993-11">{</span><span class="p" data-group-id="3705657993-11">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">request</span><span class="p" data-group-id="3705657993-12">(</span><span class="p" data-group-id="3705657993-12">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3705657993-13">{</span><span class="ss">&#39;store&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3705657993-14">(</span><span class="p" data-group-id="3705657993-14">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3705657993-15">(</span><span class="p" data-group-id="3705657993-15">)</span><span class="p" data-group-id="3705657993-13">}</span><span class="p">;</span><span class="w">
│ │ │ +                   </span><span class="p" data-group-id="3705657993-16">{</span><span class="ss">&#39;lookup&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3705657993-17">(</span><span class="p" data-group-id="3705657993-17">)</span><span class="p" data-group-id="3705657993-16">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="2340931972-18">(</span><span class="nf">request</span><span class="p" data-group-id="2340931972-19">(</span><span class="p" data-group-id="2340931972-19">)</span><span class="p">,</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="2340931972-20">(</span><span class="p" data-group-id="2340931972-20">)</span><span class="p" data-group-id="2340931972-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2340931972-21">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="2340931972-22">(</span><span class="p" data-group-id="2340931972-22">)</span><span class="p" data-group-id="2340931972-21">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">handle_req</span><span class="p" data-group-id="3705657993-18">(</span><span class="nf">request</span><span class="p" data-group-id="3705657993-19">(</span><span class="p" data-group-id="3705657993-19">)</span><span class="p">,</span><span class="w"> </span><span class="nf">state</span><span class="p" data-group-id="3705657993-20">(</span><span class="p" data-group-id="3705657993-20">)</span><span class="p" data-group-id="3705657993-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3705657993-21">{</span><span class="ss">&#39;ok&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3705657993-22">(</span><span class="p" data-group-id="3705657993-22">)</span><span class="p" data-group-id="3705657993-21">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Each <code class="inline">-spec</code> contract is to be a subtype of the respective <code class="inline">-callback</code> contract.</p>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/statem.html
│ │ │ @@ -124,15 +124,15 @@
│ │ │  </h2>
│ │ │  <p>Established Automata Theory does not deal much with how a <em>state transition</em>
│ │ │  is triggered, but assumes that the output is a function of the input
│ │ │  (and the state) and that they are some kind of values.</p><p>For an Event-Driven State Machine, the input is an <em>event</em> that triggers
│ │ │  a <em>state transition</em> and the output is actions executed during
│ │ │  the <em>state transition</em>.  Analogously to the mathematical model
│ │ │  of a Finite State Machine, it can be described as a set of relations
│ │ │ -of the following form:</p><pre><code class="makeup erlang" translate="no"><span class="n">State</span><span class="p" data-group-id="4994245978-1">(</span><span class="n">S</span><span class="p" data-group-id="4994245978-1">)</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="4994245978-2">(</span><span class="n">E</span><span class="p" data-group-id="4994245978-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Actions</span><span class="p" data-group-id="4994245978-3">(</span><span class="n">A</span><span class="p" data-group-id="4994245978-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="4994245978-4">(</span><span class="n">S</span><span class="err">&#39;</span><span class="p" data-group-id="4994245978-4">)</span></code></pre><p>These relations are interpreted as follows: if we are in state <code class="inline">S</code>,
│ │ │ +of the following form:</p><pre><code class="makeup erlang" translate="no"><span class="n">State</span><span class="p" data-group-id="5441405445-1">(</span><span class="n">S</span><span class="p" data-group-id="5441405445-1">)</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="n">Event</span><span class="p" data-group-id="5441405445-2">(</span><span class="n">E</span><span class="p" data-group-id="5441405445-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Actions</span><span class="p" data-group-id="5441405445-3">(</span><span class="n">A</span><span class="p" data-group-id="5441405445-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p" data-group-id="5441405445-4">(</span><span class="n">S</span><span class="err">&#39;</span><span class="p" data-group-id="5441405445-4">)</span></code></pre><p>These relations are interpreted as follows: if we are in state <code class="inline">S</code>,
│ │ │  and event <code class="inline">E</code> occurs, we are to perform actions <code class="inline">A</code>, and make a transition
│ │ │  to state <code class="inline">S'</code>.  Notice that <code class="inline">S'</code> can be equal to <code class="inline">S</code>,
│ │ │  and that <code class="inline">A</code> can be empty.</p><p>In <code class="inline">gen_statem</code> we define a <em>state change</em> as a <em>state transition</em> in which the
│ │ │  new state <code class="inline">S'</code> is different from the current state <code class="inline">S</code>, where &quot;different&quot; means
│ │ │  Erlang's strict inequality: <code class="inline">=/=</code> also known as &quot;does not match&quot;. <code class="inline">gen_statem</code>
│ │ │  does more things during <em>state changes</em> than during other <em>state transitions</em>.</p><p>As <code class="inline">A</code> and <code class="inline">S'</code> depend only on <code class="inline">S</code> and <code class="inline">E</code>, the kind of state machine described
│ │ │  here is a Mealy machine (see, for example, the Wikipedia article
│ │ │ @@ -405,20 +405,20 @@
│ │ │    </a>
│ │ │    <span class="text">State Enter Calls</span>
│ │ │  </h2>
│ │ │  <p>The <code class="inline">gen_statem</code> behaviour can, if this is enabled, regardless of <em>callback
│ │ │  mode</em>, automatically call the <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#t:state_enter/0"><em>state callback</em></a>
│ │ │  with special arguments whenever the state changes, so you can write
│ │ │  state enter actions near the rest of the <em>state transition</em> rules.
│ │ │ -It typically looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">StateName</span><span class="p" data-group-id="9748879377-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9748879377-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +It typically looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">StateName</span><span class="p" data-group-id="3073604227-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3073604227-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">state</span><span class="w"> </span><span class="ss">enter</span><span class="w"> </span><span class="ss">actions</span><span class="w"> </span><span class="ss">here</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9748879377-2">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="9748879377-2">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="n">StateName</span><span class="p" data-group-id="9748879377-3">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9748879377-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3073604227-2">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="3073604227-2">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="n">StateName</span><span class="p" data-group-id="3073604227-3">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3073604227-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">actions</span><span class="w"> </span><span class="ss">here</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9748879377-4">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewStateName</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="9748879377-4">}</span><span class="p">.</span></code></pre><p>Since the <em>state enter call</em> is not an event there are restrictions on the
│ │ │ +    </span><span class="p" data-group-id="3073604227-4">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="n">NewStateName</span><span class="p">,</span><span class="w"> </span><span class="n">NewData</span><span class="p" data-group-id="3073604227-4">}</span><span class="p">.</span></code></pre><p>Since the <em>state enter call</em> is not an event there are restrictions on the
│ │ │  allowed return value and state <a href="#transition-actions"><em>transition actions</em></a>.
│ │ │  You must not change the state, <a href="#postponing-events">postpone</a> this non-event,
│ │ │  <a href="#inserted-events">insert any events</a>, or change the
│ │ │  <a href="#callback-module"><em>callback module</em></a>.</p><p>The first state that is entered after <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#c:init/1"><code class="inline">gen_statem:init/1</code></a> will get
│ │ │  a <em>state enter call</em> with <code class="inline">OldState</code> equal to the current state.</p><p>You may repeat the <em>state enter call</em> using the <code class="inline">{repeat_state,...}</code> return
│ │ │  value from the <a href="#state-callback"><em>state callback</em></a>. In this case
│ │ │  <code class="inline">OldState</code> will also be equal to the current state.</p><p>Depending on how your state machine is specified, this can be a very useful
│ │ │ @@ -499,72 +499,72 @@
│ │ │  
│ │ │      locked      --&gt; check_code : {button, Button}\n* Collect Buttons
│ │ │      check_code  --&gt; locked     : Incorrect code
│ │ │      check_code  --&gt; open       : Correct code\n* do_unlock()\n* Clear Buttons\n* Set state_timeout 10 s
│ │ │  
│ │ │      open        --&gt; open   : {button, Digit}
│ │ │      open        --&gt; locked : state_timeout\n* do_lock()</code></pre><p>This code lock state machine can be implemented using <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html"><code class="inline">gen_statem</code></a> with
│ │ │ -the following <em>callback module</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5788356024-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="5788356024-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5788356024-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="5788356024-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5788356024-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock</span><span class="p" data-group-id="5788356024-3">)</span><span class="p">.</span><span class="w">
│ │ │ +the following <em>callback module</em>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5276601478-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="5276601478-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5276601478-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="5276601478-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5276601478-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock</span><span class="p" data-group-id="5276601478-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5788356024-4">(</span><span class="p" data-group-id="5788356024-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5788356024-5">]</span><span class="p" data-group-id="5788356024-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5788356024-6">(</span><span class="p" data-group-id="5788356024-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5788356024-7">]</span><span class="p" data-group-id="5788356024-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5788356024-8">(</span><span class="p" data-group-id="5788356024-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5788356024-9">]</span><span class="p" data-group-id="5788356024-8">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5788356024-10">(</span><span class="p" data-group-id="5788356024-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5788356024-11">]</span><span class="p" data-group-id="5788356024-10">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="5788356024-12">(</span><span class="n">Code</span><span class="p" data-group-id="5788356024-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5788356024-13">(</span><span class="p" data-group-id="5788356024-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="5788356024-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5788356024-15">[</span><span class="p" data-group-id="5788356024-15">]</span><span class="p" data-group-id="5788356024-13">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">button</span><span class="p" data-group-id="5788356024-16">(</span><span class="n">Button</span><span class="p" data-group-id="5788356024-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="5788356024-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5788356024-18">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5788356024-18">}</span><span class="p" data-group-id="5788356024-17">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="5788356024-19">(</span><span class="n">Code</span><span class="p" data-group-id="5788356024-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="5788356024-20">(</span><span class="p" data-group-id="5788356024-20">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5788356024-21">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="5788356024-22">(</span><span class="n">Code</span><span class="p" data-group-id="5788356024-22">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5788356024-23">[</span><span class="p" data-group-id="5788356024-23">]</span><span class="p" data-group-id="5788356024-21">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5788356024-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5788356024-24">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="5788356024-25">(</span><span class="p" data-group-id="5788356024-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="ss">state_functions</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="2456120037-1">(</span><span class="w">
│ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2456120037-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2456120037-2">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="2456120037-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="2456120037-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2456120037-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5276601478-4">(</span><span class="p" data-group-id="5276601478-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5276601478-5">]</span><span class="p" data-group-id="5276601478-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5276601478-6">(</span><span class="p" data-group-id="5276601478-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5276601478-7">]</span><span class="p" data-group-id="5276601478-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5276601478-8">(</span><span class="p" data-group-id="5276601478-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5276601478-9">]</span><span class="p" data-group-id="5276601478-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5276601478-10">(</span><span class="p" data-group-id="5276601478-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5276601478-11">]</span><span class="p" data-group-id="5276601478-10">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="5276601478-12">(</span><span class="n">Code</span><span class="p" data-group-id="5276601478-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5276601478-13">(</span><span class="p" data-group-id="5276601478-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="5276601478-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5276601478-15">[</span><span class="p" data-group-id="5276601478-15">]</span><span class="p" data-group-id="5276601478-13">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">button</span><span class="p" data-group-id="5276601478-16">(</span><span class="n">Button</span><span class="p" data-group-id="5276601478-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="5276601478-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5276601478-18">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5276601478-18">}</span><span class="p" data-group-id="5276601478-17">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="5276601478-19">(</span><span class="n">Code</span><span class="p" data-group-id="5276601478-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="5276601478-20">(</span><span class="p" data-group-id="5276601478-20">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5276601478-21">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="5276601478-22">(</span><span class="n">Code</span><span class="p" data-group-id="5276601478-22">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5276601478-23">[</span><span class="p" data-group-id="5276601478-23">]</span><span class="p" data-group-id="5276601478-21">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5276601478-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5276601478-24">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="5276601478-25">(</span><span class="p" data-group-id="5276601478-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="ss">state_functions</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="9872783619-1">(</span><span class="w">
│ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9872783619-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9872783619-2">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="9872783619-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="9872783619-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9872783619-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │          </span><span class="k">if</span><span class="w">
│ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="2456120037-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="2456120037-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="9872783619-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="9872783619-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="2456120037-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="2456120037-5">)</span><span class="w">
│ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="2456120037-6">[</span><span class="n">Button</span><span class="p" data-group-id="2456120037-6">]</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="9872783619-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="9872783619-5">)</span><span class="w">
│ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9872783619-6">[</span><span class="n">Button</span><span class="p" data-group-id="9872783619-6">]</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="2456120037-7">(</span><span class="p" data-group-id="2456120037-7">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="2456120037-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2456120037-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="2456120037-10">[</span><span class="p" data-group-id="2456120037-10">]</span><span class="p" data-group-id="2456120037-9">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="2456120037-11">[</span><span class="p" data-group-id="2456120037-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="2456120037-12">}</span><span class="p" data-group-id="2456120037-11">]</span><span class="p" data-group-id="2456120037-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="9872783619-7">(</span><span class="p" data-group-id="9872783619-7">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9872783619-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9872783619-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9872783619-10">[</span><span class="p" data-group-id="9872783619-10">]</span><span class="p" data-group-id="9872783619-9">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="9872783619-11">[</span><span class="p" data-group-id="9872783619-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="9872783619-12">}</span><span class="p" data-group-id="9872783619-11">]</span><span class="p" data-group-id="9872783619-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="2456120037-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2456120037-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="2456120037-14">}</span><span class="p" data-group-id="2456120037-13">}</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="8918513584-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="8918513584-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="8918513584-2">(</span><span class="p" data-group-id="8918513584-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8918513584-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8918513584-3">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="8918513584-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8918513584-5">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8918513584-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8918513584-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8918513584-6">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8918513584-6">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="7877153264-1">(</span><span class="p" data-group-id="7877153264-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7877153264-2">(</span><span class="s">&quot;Lock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7877153264-3">[</span><span class="p" data-group-id="7877153264-3">]</span><span class="p" data-group-id="7877153264-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="7877153264-4">(</span><span class="p" data-group-id="7877153264-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7877153264-5">(</span><span class="s">&quot;Unlock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7877153264-6">[</span><span class="p" data-group-id="7877153264-6">]</span><span class="p" data-group-id="7877153264-5">)</span><span class="p">.</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9872783619-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9872783619-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="9872783619-14">}</span><span class="p" data-group-id="9872783619-13">}</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="6735802621-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="6735802621-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="6735802621-2">(</span><span class="p" data-group-id="6735802621-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6735802621-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6735802621-3">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="6735802621-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6735802621-5">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6735802621-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6735802621-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6735802621-6">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6735802621-6">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="6902838302-1">(</span><span class="p" data-group-id="6902838302-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6902838302-2">(</span><span class="s">&quot;Lock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6902838302-3">[</span><span class="p" data-group-id="6902838302-3">]</span><span class="p" data-group-id="6902838302-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="6902838302-4">(</span><span class="p" data-group-id="6902838302-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="6902838302-5">(</span><span class="s">&quot;Unlock</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6902838302-6">[</span><span class="p" data-group-id="6902838302-6">]</span><span class="p" data-group-id="6902838302-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="7877153264-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="7877153264-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="7877153264-8">(</span><span class="p" data-group-id="7877153264-8">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="6902838302-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="6902838302-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="6902838302-8">(</span><span class="p" data-group-id="6902838302-8">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><p>The code is explained in the next sections.</p><h2 id="starting-gen_statem" class="section-heading">
│ │ │    <a href="#starting-gen_statem" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting gen_statem</span>
│ │ │  </h2>
│ │ │  <p>In the example in the previous section, <code class="inline">gen_statem</code> is started by calling
│ │ │ -<code class="inline">code_lock:start_link(Code)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="2757759060-1">(</span><span class="n">Code</span><span class="p" data-group-id="2757759060-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="2757759060-2">(</span><span class="p" data-group-id="2757759060-3">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="2757759060-3">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2757759060-4">[</span><span class="p" data-group-id="2757759060-4">]</span><span class="p" data-group-id="2757759060-2">)</span><span class="p">.</span></code></pre><p><code class="inline">start_link/1</code> calls function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start_link/4"><code class="inline">gen_statem:start_link/4</code></a>,
│ │ │ +<code class="inline">code_lock:start_link(Code)</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="5236858821-1">(</span><span class="n">Code</span><span class="p" data-group-id="5236858821-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5236858821-2">(</span><span class="p" data-group-id="5236858821-3">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="5236858821-3">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5236858821-4">[</span><span class="p" data-group-id="5236858821-4">]</span><span class="p" data-group-id="5236858821-2">)</span><span class="p">.</span></code></pre><p><code class="inline">start_link/1</code> calls function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start_link/4"><code class="inline">gen_statem:start_link/4</code></a>,
│ │ │  which spawns and links to a new process, a <code class="inline">gen_statem</code>.</p><ul><li><p>The first argument, <code class="inline">{local,?NAME}</code>, specifies the name. In this case, the
│ │ │  <code class="inline">gen_statem</code> is locally registered as <code class="inline">code_lock</code> through the macro <code class="inline">?NAME</code>.</p><p>If the name is omitted, the <code class="inline">gen_statem</code> is not registered. Instead its pid
│ │ │  must be used. The name can also be specified as <code class="inline">{global, Name}</code>, then the
│ │ │  <code class="inline">gen_statem</code> is registered using <a href="../../lib/kernel-10.2.7.2/doc/html/global.html#register_name/2"><code class="inline">global:register_name/2</code></a> in Kernel.</p></li><li><p>The second argument, <code class="inline">?MODULE</code>, is the name of the <em>callback module</em>,
│ │ │  that is, the module where the callback functions are located,
│ │ │  which is this module.</p><p>The interface functions (<code class="inline">start_link/1</code> and <code class="inline">button/1</code>) are located in the
│ │ │  same module as the callback functions (<code class="inline">init/1</code>, <code class="inline">locked/3</code>, and <code class="inline">open/3</code>).
│ │ │ @@ -574,184 +574,184 @@
│ │ │  see <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3</code></a>.</p></li></ul><p>If name registration succeeds, the new <code class="inline">gen_statem</code> process calls callback
│ │ │  function <code class="inline">code_lock:init(Code)</code>. This function is expected to return
│ │ │  <code class="inline">{ok, State, Data}</code>, where <code class="inline">State</code> is the initial state of the <code class="inline">gen_statem</code>,
│ │ │  in this case <code class="inline">locked</code>; assuming that the door is locked to begin with.
│ │ │  <code class="inline">Data</code> is the internal server data of the <code class="inline">gen_statem</code>. Here the server data
│ │ │  is a <a href="../../lib/stdlib-6.2.2.2/doc/html/maps.html"><code class="inline">map()</code></a> with key <code class="inline">code</code> that stores the correct
│ │ │  button sequence, key <code class="inline">length</code> store its length, and key <code class="inline">buttons</code>
│ │ │ -that stores the collected buttons up to the same length.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1809087394-1">(</span><span class="n">Code</span><span class="p" data-group-id="1809087394-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="1809087394-2">(</span><span class="p" data-group-id="1809087394-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1809087394-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="1809087394-4">(</span><span class="n">Code</span><span class="p" data-group-id="1809087394-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1809087394-5">[</span><span class="p" data-group-id="1809087394-5">]</span><span class="p" data-group-id="1809087394-3">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1809087394-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1809087394-6">}</span><span class="p">.</span></code></pre><p>Function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3,4</code></a>
│ │ │ +that stores the collected buttons up to the same length.</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0612370343-1">(</span><span class="n">Code</span><span class="p" data-group-id="0612370343-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="0612370343-2">(</span><span class="p" data-group-id="0612370343-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0612370343-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="0612370343-4">(</span><span class="n">Code</span><span class="p" data-group-id="0612370343-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0612370343-5">[</span><span class="p" data-group-id="0612370343-5">]</span><span class="p" data-group-id="0612370343-3">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0612370343-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0612370343-6">}</span><span class="p">.</span></code></pre><p>Function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3,4</code></a>
│ │ │  is synchronous. It does not return until the <code class="inline">gen_statem</code> is initialized
│ │ │  and is ready to receive events.</p><p>Function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start_link/3"><code class="inline">gen_statem:start_link/3,4</code></a>
│ │ │  must be used if the <code class="inline">gen_statem</code> is part of a supervision tree, that is,
│ │ │  started by a supervisor.  Function,
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start/3"><code class="inline">gen_statem:start/3,4</code></a> can be used to start
│ │ │  a standalone <code class="inline">gen_statem</code>, meaning it is not part of a supervision tree.</p><p>Function <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#c:callback_mode/0"><code class="inline">Module:callback_mode/0</code></a> selects
│ │ │  the <a href="#callback-modes"><code class="inline">CallbackMode</code></a> for the <em>callback module</em>,
│ │ │  in this case <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#t:callback_mode/0"><code class="inline">state_functions</code></a>.
│ │ │ -That is, each state has its own handler function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="1807353680-1">(</span><span class="p" data-group-id="1807353680-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +That is, each state has its own handler function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="8127690994-1">(</span><span class="p" data-group-id="8127690994-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">state_functions</span><span class="p">.</span></code></pre><h2 id="handling-events" class="section-heading">
│ │ │    <a href="#handling-events" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Handling Events</span>
│ │ │  </h2>
│ │ │  <p>The function notifying the code lock about a button event is implemented using
│ │ │ -<a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#cast/2"><code class="inline">gen_statem:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">button</span><span class="p" data-group-id="8111642427-1">(</span><span class="n">Button</span><span class="p" data-group-id="8111642427-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="8111642427-2">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8111642427-3">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8111642427-3">}</span><span class="p" data-group-id="8111642427-2">)</span><span class="p">.</span></code></pre><p>The first argument is the name of the <code class="inline">gen_statem</code> and must agree with
│ │ │ +<a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#cast/2"><code class="inline">gen_statem:cast/2</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">button</span><span class="p" data-group-id="5079160115-1">(</span><span class="n">Button</span><span class="p" data-group-id="5079160115-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="5079160115-2">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5079160115-3">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5079160115-3">}</span><span class="p" data-group-id="5079160115-2">)</span><span class="p">.</span></code></pre><p>The first argument is the name of the <code class="inline">gen_statem</code> and must agree with
│ │ │  the name used to start it. So, we use the same macro <code class="inline">?NAME</code> as when starting.
│ │ │  <code class="inline">{button, Button}</code> is the event content.</p><p>The event is sent to the <code class="inline">gen_statem</code>. When the event is received, the
│ │ │  <code class="inline">gen_statem</code> calls <code class="inline">StateName(cast, Event, Data)</code>, which is expected
│ │ │  to return a tuple <code class="inline">{next_state, NewStateName, NewData}</code>, or
│ │ │  <code class="inline">{next_state, NewStateName, NewData, Actions}</code>. <code class="inline">StateName</code> is the name
│ │ │  of the current state and <code class="inline">NewStateName</code> is the name of the next state.
│ │ │  <code class="inline">NewData</code> is a new value for the server data of the <code class="inline">gen_statem</code>,
│ │ │ -and <code class="inline">Actions</code> is a list of actions to be performed by the <code class="inline">gen_statem</code> engine.</p><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="7140395714-1">(</span><span class="w">
│ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7140395714-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7140395714-2">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="7140395714-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="7140395714-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7140395714-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +and <code class="inline">Actions</code> is a list of actions to be performed by the <code class="inline">gen_statem</code> engine.</p><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="0043477882-1">(</span><span class="w">
│ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0043477882-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0043477882-2">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="0043477882-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="0043477882-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0043477882-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │          </span><span class="k">if</span><span class="w">
│ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="7140395714-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="7140395714-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="0043477882-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="0043477882-4">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="7140395714-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="7140395714-5">)</span><span class="w">
│ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="7140395714-6">[</span><span class="n">Button</span><span class="p" data-group-id="7140395714-6">]</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="0043477882-5">(</span><span class="n">Buttons</span><span class="p" data-group-id="0043477882-5">)</span><span class="w">
│ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="0043477882-6">[</span><span class="n">Button</span><span class="p" data-group-id="0043477882-6">]</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="7140395714-7">(</span><span class="p" data-group-id="7140395714-7">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="7140395714-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7140395714-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="7140395714-10">[</span><span class="p" data-group-id="7140395714-10">]</span><span class="p" data-group-id="7140395714-9">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="7140395714-11">[</span><span class="p" data-group-id="7140395714-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="7140395714-12">}</span><span class="p" data-group-id="7140395714-11">]</span><span class="p" data-group-id="7140395714-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="0043477882-7">(</span><span class="p" data-group-id="0043477882-7">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="0043477882-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0043477882-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="0043477882-10">[</span><span class="p" data-group-id="0043477882-10">]</span><span class="p" data-group-id="0043477882-9">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="0043477882-11">[</span><span class="p" data-group-id="0043477882-12">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="0043477882-12">}</span><span class="p" data-group-id="0043477882-11">]</span><span class="p" data-group-id="0043477882-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="7140395714-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7140395714-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="7140395714-14">}</span><span class="p" data-group-id="7140395714-13">}</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="0043477882-13">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0043477882-14">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="0043477882-14">}</span><span class="p" data-group-id="0043477882-13">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>In state <code class="inline">locked</code>, when a button is pressed, it is collected with the
│ │ │  previously pressed buttons up to the length of the correct code, then
│ │ │  compared with the correct code. Depending on the result, the door is
│ │ │  either unlocked and the <code class="inline">gen_statem</code> goes to state <code class="inline">open</code>, or the door
│ │ │  remains in state <code class="inline">locked</code>.</p><p>When changing to state <code class="inline">open</code>, the collected buttons are reset, the lock
│ │ │ -unlocked, and a <em>state time-out</em> for 10 seconds is started.</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="6865309927-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6865309927-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6865309927-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6865309927-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6865309927-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6865309927-3">}</span><span class="p">.</span></code></pre><p>In state <code class="inline">open</code>, a button event is ignored by staying in the same state.
│ │ │ +unlocked, and a <em>state time-out</em> for 10 seconds is started.</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="8699947550-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8699947550-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8699947550-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8699947550-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8699947550-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8699947550-3">}</span><span class="p">.</span></code></pre><p>In state <code class="inline">open</code>, a button event is ignored by staying in the same state.
│ │ │  This can also be done by returning <code class="inline">{keep_state, Data}</code>, or in this case
│ │ │  since <code class="inline">Data</code> is unchanged, by returning <code class="inline">keep_state_and_data</code>.</p><h2 id="state-time-outs" class="section-heading">
│ │ │    <a href="#state-time-outs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">State Time-Outs</span>
│ │ │  </h2>
│ │ │  <p>When a correct code has been given, the door is unlocked and the following
│ │ │ -tuple is returned from <code class="inline">locked/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9242954671-1">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9242954671-2">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9242954671-3">[</span><span class="p" data-group-id="9242954671-3">]</span><span class="p" data-group-id="9242954671-2">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="9242954671-4">[</span><span class="p" data-group-id="9242954671-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="9242954671-5">}</span><span class="p" data-group-id="9242954671-4">]</span><span class="p" data-group-id="9242954671-1">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span></code></pre><p>10,000 is a time-out value in milliseconds. After this time (10 seconds),
│ │ │ +tuple is returned from <code class="inline">locked/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5733242845-1">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5733242845-2">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="5733242845-3">[</span><span class="p" data-group-id="5733242845-3">]</span><span class="p" data-group-id="5733242845-2">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="5733242845-4">[</span><span class="p" data-group-id="5733242845-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="5733242845-5">}</span><span class="p" data-group-id="5733242845-4">]</span><span class="p" data-group-id="5733242845-1">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span></code></pre><p>10,000 is a time-out value in milliseconds. After this time (10 seconds),
│ │ │  a time-out occurs. Then, <code class="inline">StateName(state_timeout, lock, Data)</code> is called.
│ │ │  The time-out occurs when the door has been in state <code class="inline">open</code> for 10 seconds.
│ │ │ -After that the door is locked again:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="9915566958-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="9915566958-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="9915566958-2">(</span><span class="p" data-group-id="9915566958-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9915566958-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9915566958-3">}</span><span class="p">;</span></code></pre><p>The timer for a <em>state time-out</em> is automatically canceled when
│ │ │ +After that the door is locked again:</p><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="1044418281-1">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w">  </span><span class="n">Data</span><span class="p" data-group-id="1044418281-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="1044418281-2">(</span><span class="p" data-group-id="1044418281-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1044418281-3">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1044418281-3">}</span><span class="p">;</span></code></pre><p>The timer for a <em>state time-out</em> is automatically canceled when
│ │ │  the state machine does a <em>state change</em>.</p><p>You can restart, cancel, or update a <em>state time-out</em>. See section
│ │ │  <a href="#time-outs"><em>Time-Outs</em></a> for details.</p><h2 id="all-state-events" class="section-heading">
│ │ │    <a href="#all-state-events" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">All State Events</span>
│ │ │  </h2>
│ │ │  <p>Sometimes events can arrive in any state of the <code class="inline">gen_statem</code>. It is convenient
│ │ │  to handle these in a common state handler function that all state functions
│ │ │  call for events not specific to the state.</p><p>Consider a <code class="inline">code_length/0</code> function that returns the length
│ │ │  of the correct code.  We dispatch all events that are not state-specific
│ │ │  to the common function <code class="inline">handle_common/3</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6520200858-1">(</span><span class="p" data-group-id="6520200858-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="6520200858-2">]</span><span class="p" data-group-id="6520200858-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1621622836-1">(</span><span class="p" data-group-id="1621622836-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1621622836-2">]</span><span class="p" data-group-id="1621622836-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">code_length</span><span class="p" data-group-id="6520200858-3">(</span><span class="p" data-group-id="6520200858-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="6520200858-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="6520200858-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">code_length</span><span class="p" data-group-id="1621622836-3">(</span><span class="p" data-group-id="1621622836-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="1621622836-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="1621622836-4">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="6520200858-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6520200858-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="6520200858-6">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6520200858-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">handle_common</span><span class="p" data-group-id="6520200858-7">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6520200858-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="1621622836-5">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1621622836-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="1621622836-6">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1621622836-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">handle_common</span><span class="p" data-group-id="1621622836-7">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1621622836-7">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="6520200858-8">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="6520200858-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="6520200858-9">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6520200858-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">handle_common</span><span class="p" data-group-id="6520200858-10">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6520200858-10">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="6520200858-11">(</span><span class="p" data-group-id="6520200858-12">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="6520200858-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6520200858-13">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="6520200858-13">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6520200858-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6520200858-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="6520200858-15">[</span><span class="p" data-group-id="6520200858-16">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="6520200858-17">(</span><span class="n">Code</span><span class="p" data-group-id="6520200858-17">)</span><span class="p" data-group-id="6520200858-16">}</span><span class="p" data-group-id="6520200858-15">]</span><span class="p" data-group-id="6520200858-14">}</span><span class="p">.</span></code></pre><p>Another way to do it is through a convenience macro <code class="inline">?HANDLE_COMMON/0</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="2597063870-1">(</span><span class="p" data-group-id="2597063870-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="2597063870-2">]</span><span class="p" data-group-id="2597063870-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1621622836-8">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1621622836-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1621622836-9">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1621622836-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">handle_common</span><span class="p" data-group-id="1621622836-10">(</span><span class="n">EventType</span><span class="p">,</span><span class="w"> </span><span class="n">EventContent</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1621622836-10">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="1621622836-11">(</span><span class="p" data-group-id="1621622836-12">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="1621622836-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1621622836-13">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="1621622836-13">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1621622836-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1621622836-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="1621622836-15">[</span><span class="p" data-group-id="1621622836-16">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="1621622836-17">(</span><span class="n">Code</span><span class="p" data-group-id="1621622836-17">)</span><span class="p" data-group-id="1621622836-16">}</span><span class="p" data-group-id="1621622836-15">]</span><span class="p" data-group-id="1621622836-14">}</span><span class="p">.</span></code></pre><p>Another way to do it is through a convenience macro <code class="inline">?HANDLE_COMMON/0</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1186334755-1">(</span><span class="p" data-group-id="1186334755-2">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1186334755-2">]</span><span class="p" data-group-id="1186334755-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">code_length</span><span class="p" data-group-id="2597063870-3">(</span><span class="p" data-group-id="2597063870-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="2597063870-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="2597063870-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">code_length</span><span class="p" data-group-id="1186334755-3">(</span><span class="p" data-group-id="1186334755-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="1186334755-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="1186334755-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="2597063870-5">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="2597063870-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="2597063870-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="2597063870-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="2597063870-7">)</span><span class="p" data-group-id="2597063870-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1186334755-5">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="1186334755-6">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="1186334755-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="1186334755-7">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="1186334755-7">)</span><span class="p" data-group-id="1186334755-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="2597063870-8">(</span><span class="p" data-group-id="2597063870-9">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="2597063870-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2597063870-10">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="2597063870-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="2597063870-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2597063870-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="2597063870-12">[</span><span class="p" data-group-id="2597063870-13">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="2597063870-14">(</span><span class="n">Code</span><span class="p" data-group-id="2597063870-14">)</span><span class="p" data-group-id="2597063870-13">}</span><span class="p" data-group-id="2597063870-12">]</span><span class="p" data-group-id="2597063870-11">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="1186334755-8">(</span><span class="p" data-group-id="1186334755-9">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="1186334755-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1186334755-10">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="1186334755-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1186334755-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1186334755-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="1186334755-12">[</span><span class="p" data-group-id="1186334755-13">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="1186334755-14">(</span><span class="n">Code</span><span class="p" data-group-id="1186334755-14">)</span><span class="p" data-group-id="1186334755-13">}</span><span class="p" data-group-id="1186334755-12">]</span><span class="p" data-group-id="1186334755-11">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="2597063870-15">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2597063870-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="1186334755-15">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1186334755-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │  </span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="2597063870-16">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2597063870-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="1186334755-16">(</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1186334755-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="p">;</span><span class="w">
│ │ │  </span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span></code></pre><p>This example uses <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#call/2"><code class="inline">gen_statem:call/2</code></a>, which waits for a reply from the server.
│ │ │  The reply is sent with a <code class="inline">{reply, From, Reply}</code> tuple in an action list in the
│ │ │  <code class="inline">{keep_state, ...}</code> tuple that retains the current state. This return form is
│ │ │  convenient when you want to stay in the current state but do not know or care
│ │ │  about what it is.</p><p>If the common <em>state callback</em> needs to know the current state a function
│ │ │ -<code class="inline">handle_common/4</code> can be used instead:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5777326138-1">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="5777326138-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="5777326138-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="5777326138-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="5777326138-3">)</span><span class="p" data-group-id="5777326138-1">)</span><span class="p">.</span></code></pre><h2 id="one-state-callback" class="section-heading">
│ │ │ +<code class="inline">handle_common/4</code> can be used instead:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6394347309-1">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="6394347309-2">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="6394347309-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="6394347309-3">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="6394347309-3">)</span><span class="p" data-group-id="6394347309-1">)</span><span class="p">.</span></code></pre><h2 id="one-state-callback" class="section-heading">
│ │ │    <a href="#one-state-callback" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">One State Callback</span>
│ │ │  </h2>
│ │ │  <p>If <a href="#callback-modes"><em>callback mode</em></a> <code class="inline">handle_event_function</code> is used,
│ │ │  all events are handled in
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#c:handle_event/4"><code class="inline">Module:handle_event/4</code></a> and we can
│ │ │  (but do not have to) use an event-centered approach where we first branch
│ │ │  depending on event and then depending on state:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0491618496-1">(</span><span class="p" data-group-id="0491618496-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="0491618496-2">]</span><span class="p" data-group-id="0491618496-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8814459779-1">(</span><span class="p" data-group-id="8814459779-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="8814459779-2">]</span><span class="p" data-group-id="8814459779-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="0491618496-3">(</span><span class="p" data-group-id="0491618496-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="8814459779-3">(</span><span class="p" data-group-id="8814459779-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">handle_event_function</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0491618496-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0491618496-5">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0491618496-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0491618496-6">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="0491618496-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0491618496-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="8814459779-4">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8814459779-5">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8814459779-5">}</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8814459779-6">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="8814459779-6">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8814459779-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">State</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │  	</span><span class="ss">locked</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0491618496-7">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="0491618496-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="8814459779-7">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="8814459779-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │                  </span><span class="k">if</span><span class="w">
│ │ │ -                    </span><span class="nf">length</span><span class="p" data-group-id="0491618496-8">(</span><span class="n">Buttons</span><span class="p" data-group-id="0491618496-8">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                    </span><span class="nf">length</span><span class="p" data-group-id="8814459779-8">(</span><span class="n">Buttons</span><span class="p" data-group-id="8814459779-8">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                          </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │                      </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                        </span><span class="nf">tl</span><span class="p" data-group-id="0491618496-9">(</span><span class="n">Buttons</span><span class="p" data-group-id="0491618496-9">)</span><span class="w">
│ │ │ -                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="0491618496-10">[</span><span class="n">Button</span><span class="p" data-group-id="0491618496-10">]</span><span class="p">,</span><span class="w">
│ │ │ +                        </span><span class="nf">tl</span><span class="p" data-group-id="8814459779-9">(</span><span class="n">Buttons</span><span class="p" data-group-id="8814459779-9">)</span><span class="w">
│ │ │ +                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="8814459779-10">[</span><span class="n">Button</span><span class="p" data-group-id="8814459779-10">]</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="k">if</span><span class="w">
│ │ │                  </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="0491618496-11">(</span><span class="p" data-group-id="0491618496-11">)</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="0491618496-12">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0491618496-13">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="0491618496-14">[</span><span class="p" data-group-id="0491618496-14">]</span><span class="p" data-group-id="0491618496-13">}</span><span class="p">,</span><span class="w">
│ │ │ -                     </span><span class="p" data-group-id="0491618496-15">[</span><span class="p" data-group-id="0491618496-16">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="0491618496-16">}</span><span class="p" data-group-id="0491618496-15">]</span><span class="p" data-group-id="0491618496-12">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="8814459779-11">(</span><span class="p" data-group-id="8814459779-11">)</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="8814459779-12">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8814459779-13">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="8814459779-14">[</span><span class="p" data-group-id="8814459779-14">]</span><span class="p" data-group-id="8814459779-13">}</span><span class="p">,</span><span class="w">
│ │ │ +                     </span><span class="p" data-group-id="8814459779-15">[</span><span class="p" data-group-id="8814459779-16">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="8814459779-16">}</span><span class="p" data-group-id="8814459779-15">]</span><span class="p" data-group-id="8814459779-12">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │                  </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="0491618496-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0491618496-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="0491618496-18">}</span><span class="p" data-group-id="0491618496-17">}</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="8814459779-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8814459779-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="8814459779-18">}</span><span class="p" data-group-id="8814459779-17">}</span><span class="w">
│ │ │              </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">open</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0491618496-19">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0491618496-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="0491618496-20">(</span><span class="p" data-group-id="0491618496-20">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0491618496-21">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0491618496-21">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0491618496-22">(</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0491618496-23">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="0491618496-23">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0491618496-24">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="0491618496-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0491618496-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0491618496-25">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="0491618496-26">[</span><span class="p" data-group-id="0491618496-27">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="0491618496-28">(</span><span class="n">Code</span><span class="p" data-group-id="0491618496-28">)</span><span class="p" data-group-id="0491618496-27">}</span><span class="p" data-group-id="0491618496-26">]</span><span class="p" data-group-id="0491618496-25">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="8814459779-19">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8814459779-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="8814459779-20">(</span><span class="p" data-group-id="8814459779-20">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8814459779-21">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8814459779-21">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="8814459779-22">(</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8814459779-23">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="8814459779-23">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8814459779-24">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="8814459779-24">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8814459779-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8814459779-25">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="8814459779-26">[</span><span class="p" data-group-id="8814459779-27">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="8814459779-28">(</span><span class="n">Code</span><span class="p" data-group-id="8814459779-28">)</span><span class="p" data-group-id="8814459779-27">}</span><span class="p" data-group-id="8814459779-26">]</span><span class="p" data-group-id="8814459779-25">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><h2 id="stopping" class="section-heading">
│ │ │    <a href="#stopping" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Stopping</span>
│ │ │  </h2>
│ │ │ @@ -763,59 +763,59 @@
│ │ │  </h3>
│ │ │  <p>If the <code class="inline">gen_statem</code> is part of a supervision tree, no stop function is needed.
│ │ │  The <code class="inline">gen_statem</code> is automatically terminated by its supervisor. Exactly how
│ │ │  this is done is defined by a <a href="sup_princ.html#shutdown">shutdown strategy</a>
│ │ │  set in the supervisor.</p><p>If it is necessary to clean up before termination, the shutdown strategy
│ │ │  must be a time-out value and the <code class="inline">gen_statem</code> must in function <code class="inline">init/1</code>
│ │ │  set itself to trap exit signals by calling
│ │ │ -<a href="../../erts-15.2.7.3/doc/html/erlang.html#process_flag/2"><code class="inline">process_flag(trap_exit, true)</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="6531306942-1">(</span><span class="n">Args</span><span class="p" data-group-id="6531306942-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="6531306942-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6531306942-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="6531306942-3">(</span><span class="p" data-group-id="6531306942-3">)</span><span class="p">,</span><span class="w">
│ │ │ +<a href="../../erts-15.2.7.3/doc/html/erlang.html#process_flag/2"><code class="inline">process_flag(trap_exit, true)</code></a>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="5126594689-1">(</span><span class="n">Args</span><span class="p" data-group-id="5126594689-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="5126594689-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="5126594689-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="5126594689-3">(</span><span class="p" data-group-id="5126594689-3">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>When ordered to shut down, the <code class="inline">gen_statem</code> then calls callback function
│ │ │  <code class="inline">terminate(shutdown, State, Data)</code>.</p><p>In this example, function <code class="inline">terminate/3</code> locks the door if it is open,
│ │ │  so we do not accidentally leave the door open
│ │ │ -when the supervision tree terminates:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="8287838226-1">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="8287838226-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="8287838226-2">(</span><span class="p" data-group-id="8287838226-2">)</span><span class="p">,</span><span class="w">
│ │ │ +when the supervision tree terminates:</p><pre><code class="makeup erlang" translate="no"><span class="nf">terminate</span><span class="p" data-group-id="5662317073-1">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="5662317073-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="5662317073-2">(</span><span class="p" data-group-id="5662317073-2">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h3 id="standalone-gen_statem" class="section-heading">
│ │ │    <a href="#standalone-gen_statem" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Standalone gen_statem</span>
│ │ │  </h3>
│ │ │  <p>If the <code class="inline">gen_statem</code> is not part of a supervision tree, it can be stopped
│ │ │  using <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#stop/1"><code class="inline">gen_statem:stop/1</code></a>, preferably through
│ │ │  an API function:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1590381489-1">(</span><span class="p" data-group-id="1590381489-2">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1590381489-2">]</span><span class="p" data-group-id="1590381489-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1849908314-1">(</span><span class="p" data-group-id="1849908314-2">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1849908314-2">]</span><span class="p" data-group-id="1849908314-1">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="1590381489-3">(</span><span class="p" data-group-id="1590381489-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="1590381489-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="1590381489-4">)</span><span class="p">.</span></code></pre><p>This makes the <code class="inline">gen_statem</code> call callback function <code class="inline">terminate/3</code> just like
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="1849908314-3">(</span><span class="p" data-group-id="1849908314-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="1849908314-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="1849908314-4">)</span><span class="p">.</span></code></pre><p>This makes the <code class="inline">gen_statem</code> call callback function <code class="inline">terminate/3</code> just like
│ │ │  for a supervised server and waits for the process to terminate.</p><h2 id="event-time-outs" class="section-heading">
│ │ │    <a href="#event-time-outs" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Event Time-Outs</span>
│ │ │  </h2>
│ │ │  <p>A time-out feature inherited from <code class="inline">gen_statem</code>'s predecessor <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_fsm.html"><code class="inline">gen_fsm</code></a>,
│ │ │  is an <em>event time-out</em>, that is, if an event arrives the timer is canceled.
│ │ │  You get either an event or a time-out, but not both.</p><p>It is ordered by the
│ │ │  <a href="#transition-actions"><em>transition action</em></a> <code class="inline">{timeout, Time, EventContent}</code>,
│ │ │  or just an integer <code class="inline">Time</code>, even without the enclosing actions list (the latter
│ │ │  is a form inherited from <code class="inline">gen_fsm</code>).</p><p>This type of time-out is useful, for example, to act on inactivity.
│ │ │  Let's restart the code sequence if no button is pressed for say 30 seconds:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="7670826704-1">(</span><span class="ss">timeout</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7670826704-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7670826704-2">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7670826704-3">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="7670826704-4">[</span><span class="p" data-group-id="7670826704-4">]</span><span class="p" data-group-id="7670826704-3">}</span><span class="p" data-group-id="7670826704-2">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="7670826704-5">(</span><span class="w">
│ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7670826704-6">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7670826704-6">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="7670826704-7">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="7670826704-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7670826704-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="8989709220-1">(</span><span class="ss">timeout</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8989709220-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8989709220-2">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8989709220-3">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="8989709220-4">[</span><span class="p" data-group-id="8989709220-4">]</span><span class="p" data-group-id="8989709220-3">}</span><span class="p" data-group-id="8989709220-2">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="8989709220-5">(</span><span class="w">
│ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8989709220-6">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8989709220-6">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="8989709220-7">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="8989709220-7">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8989709220-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="7670826704-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7670826704-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="7670826704-9">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p" data-group-id="7670826704-8">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="8989709220-8">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8989709220-9">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="8989709220-9">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p" data-group-id="8989709220-8">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Whenever we receive a button event we start an <em>event time-out</em> of 30 seconds,
│ │ │  and if we get an <em>event type</em> of <code class="inline">timeout</code> we reset the remaining
│ │ │  code sequence.</p><p>An <em>event time-out</em> is canceled by any other event so you either get
│ │ │  some other event or the time-out event. Therefore, canceling,
│ │ │  restarting, or updating an <em>event time-out</em> is neither possible nor
│ │ │  necessary. Whatever event you act on has already canceled
│ │ │  the <em>event time-out</em>, so there is never a running <em>event time-out</em>
│ │ │ @@ -834,30 +834,30 @@
│ │ │  another, maybe cancel the time-out without changing states, or perhaps run
│ │ │  multiple time-outs in parallel. All this can be accomplished with
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#t:generic_timeout/0"><em>generic time-outs</em></a>. They may look a little
│ │ │  bit like <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#t:event_timeout/0"><em>event time-outs</em></a> but contain
│ │ │  a name to allow for any number of them simultaneously and they are
│ │ │  not automatically canceled.</p><p>Here is how to accomplish the <em>state time-out</em> in the previous example
│ │ │  by instead using a <em>generic time-out</em> named for example <code class="inline">open</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="8418978384-1">(</span><span class="w">
│ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8418978384-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8418978384-2">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8418978384-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="8418978384-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8418978384-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="4008721409-1">(</span><span class="w">
│ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4008721409-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4008721409-2">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="4008721409-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="4008721409-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4008721409-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="8418978384-4">(</span><span class="p" data-group-id="8418978384-4">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="8418978384-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8418978384-6">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="8418978384-7">[</span><span class="p" data-group-id="8418978384-7">]</span><span class="p" data-group-id="8418978384-6">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="8418978384-8">[</span><span class="p" data-group-id="8418978384-9">{</span><span class="p" data-group-id="8418978384-10">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="8418978384-10">}</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="8418978384-9">}</span><span class="p" data-group-id="8418978384-8">]</span><span class="p" data-group-id="8418978384-5">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="4008721409-4">(</span><span class="p" data-group-id="4008721409-4">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="4008721409-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4008721409-6">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="4008721409-7">[</span><span class="p" data-group-id="4008721409-7">]</span><span class="p" data-group-id="4008721409-6">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="4008721409-8">[</span><span class="p" data-group-id="4008721409-9">{</span><span class="p" data-group-id="4008721409-10">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="4008721409-10">}</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="4008721409-9">}</span><span class="p" data-group-id="4008721409-8">]</span><span class="p" data-group-id="4008721409-5">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="8418978384-11">(</span><span class="p" data-group-id="8418978384-12">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="8418978384-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8418978384-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="8418978384-13">(</span><span class="p" data-group-id="8418978384-13">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8418978384-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="8418978384-14">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="8418978384-15">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8418978384-16">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="8418978384-16">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8418978384-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8418978384-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="8418978384-17">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="4008721409-11">(</span><span class="p" data-group-id="4008721409-12">{</span><span class="ss">timeout</span><span class="p">,</span><span class="ss">open</span><span class="p" data-group-id="4008721409-12">}</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4008721409-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="4008721409-13">(</span><span class="p" data-group-id="4008721409-13">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4008721409-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="4008721409-14">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="4008721409-15">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4008721409-16">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4008721409-16">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4008721409-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4008721409-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="4008721409-17">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Specific <em>generic time-outs</em> can just as <a href="#state-time-outs"><em>state time-outs</em></a>
│ │ │  be restarted or canceled by setting it to a new time or <code class="inline">infinity</code>.</p><p>In this particular case we do not need to cancel the time-out since
│ │ │  the time-out event is the only possible reason to do a <em>state change</em>
│ │ │  from <code class="inline">open</code> to <code class="inline">locked</code>.</p><p>Instead of bothering with when to cancel a time-out, a late time-out event
│ │ │  can be handled by ignoring it if it arrives in a state
│ │ │  where it is known to be late.</p><p>You can restart, cancel, or update a <em>generic time-out</em>.
│ │ │  See section <a href="#time-outs"><em>Time-Outs</em></a> for details.</p><h2 id="erlang-timers" class="section-heading">
│ │ │ @@ -869,32 +869,32 @@
│ │ │  <p>The most versatile way to handle time-outs is to use Erlang Timers; see
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#start_timer/4"><code class="inline">erlang:start_timer/3,4</code></a>. Most time-out tasks
│ │ │  can be performed with the time-out features in <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html"><code class="inline">gen_statem</code></a>,
│ │ │  but an example of one that cannot is if you should need the return value
│ │ │  from <a href="../../erts-15.2.7.3/doc/html/erlang.html#cancel_timer/2"><code class="inline">erlang:cancel_timer(Tref)</code></a>, that is,
│ │ │  the remaining time of the timer.</p><p>Here is how to accomplish the <em>state time-out</em> in the previous example
│ │ │  by instead using an Erlang Timer:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="0075534935-1">(</span><span class="w">
│ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0075534935-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0075534935-2">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0075534935-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="0075534935-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0075534935-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="7580736649-1">(</span><span class="w">
│ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7580736649-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7580736649-2">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7580736649-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="7580736649-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7580736649-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="0075534935-4">(</span><span class="p" data-group-id="0075534935-4">)</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="nf">do_unlock</span><span class="p" data-group-id="7580736649-4">(</span><span class="p" data-group-id="7580736649-4">)</span><span class="p">,</span><span class="w">
│ │ │  	    </span><span class="n">Tref</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ -                 </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">start_timer</span><span class="p" data-group-id="0075534935-5">(</span><span class="w">
│ │ │ -                     </span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="0075534935-6">(</span><span class="p" data-group-id="0075534935-6">)</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p" data-group-id="0075534935-5">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0075534935-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0075534935-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="0075534935-9">[</span><span class="p" data-group-id="0075534935-9">]</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="0075534935-8">}</span><span class="p" data-group-id="0075534935-7">}</span><span class="p">;</span><span class="w">
│ │ │ +                 </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">start_timer</span><span class="p" data-group-id="7580736649-5">(</span><span class="w">
│ │ │ +                     </span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7580736649-6">(</span><span class="p" data-group-id="7580736649-6">)</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p" data-group-id="7580736649-5">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="7580736649-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7580736649-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="7580736649-9">[</span><span class="p" data-group-id="7580736649-9">]</span><span class="p">,</span><span class="w"> </span><span class="ss">timer</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="7580736649-8">}</span><span class="p" data-group-id="7580736649-7">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="0075534935-10">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0075534935-11">{</span><span class="ss">timeout</span><span class="p">,</span><span class="n">Tref</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="0075534935-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0075534935-12">#{</span><span class="ss">timer</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="0075534935-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0075534935-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="0075534935-13">(</span><span class="p" data-group-id="0075534935-13">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0075534935-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="0075534935-15">(</span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0075534935-15">)</span><span class="p" data-group-id="0075534935-14">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="0075534935-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0075534935-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0075534935-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0075534935-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0075534935-18">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="0075534935-18">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="7580736649-10">(</span><span class="ss">info</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7580736649-11">{</span><span class="ss">timeout</span><span class="p">,</span><span class="n">Tref</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="7580736649-11">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7580736649-12">#{</span><span class="ss">timer</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Tref</span><span class="p" data-group-id="7580736649-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7580736649-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="7580736649-13">(</span><span class="p" data-group-id="7580736649-13">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7580736649-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="ss">locked</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="7580736649-15">(</span><span class="ss">timer</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7580736649-15">)</span><span class="p" data-group-id="7580736649-14">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="7580736649-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7580736649-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7580736649-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7580736649-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7580736649-18">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="7580736649-18">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Removing the <code class="inline">timer</code> key from the map when we do a <em>state change</em> to <code class="inline">locked</code>
│ │ │  is not strictly necessary since we can only get into state <code class="inline">open</code>
│ │ │  with an updated <code class="inline">timer</code> map value. But it can be nice to not have
│ │ │  outdated values in the state <code class="inline">Data</code>.</p><p>If you need to cancel a timer because of some other event, you can use
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#cancel_timer/2"><code class="inline">erlang:cancel_timer(Tref)</code></a>. Note that no time-out
│ │ │  message will arrive after this (because the timer has been
│ │ │  explicitly canceled), unless you have already postponed one earlier
│ │ │ @@ -910,16 +910,16 @@
│ │ │    <span class="text">Postponing Events</span>
│ │ │  </h2>
│ │ │  <p>If you want to ignore a particular event in the current state and handle it
│ │ │  in a future state, you can postpone the event. A postponed event
│ │ │  is retried after a <em>state change</em>, that is, <code class="inline">OldState =/= NewState</code>.</p><p>Postponing is ordered by the
│ │ │  <a href="#transition-actions"><em>transition action</em></a> <code class="inline">postpone</code>.</p><p>In this example, instead of ignoring button events while in the <code class="inline">open</code> state,
│ │ │  we can postpone them handle them later in the <code class="inline">locked</code> state:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="0675585861-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0675585861-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0675585861-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0675585861-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0675585861-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="0675585861-4">[</span><span class="ss">postpone</span><span class="p" data-group-id="0675585861-4">]</span><span class="p" data-group-id="0675585861-3">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="5994855666-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5994855666-2">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5994855666-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5994855666-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5994855666-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="5994855666-4">[</span><span class="ss">postpone</span><span class="p" data-group-id="5994855666-4">]</span><span class="p" data-group-id="5994855666-3">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>Since a postponed event is only retried after a <em>state change</em>, you have to
│ │ │  think about where to keep a state data item. You can keep it in the server
│ │ │  <code class="inline">Data</code> or in the <code class="inline">State</code> itself, for example by having two more or less
│ │ │  identical states to keep a boolean value, or by using a complex state (see
│ │ │  section <a href="#complex-state"><em>Complex State</em></a>) with
│ │ │  <a href="#callback-modes"><em>callback mode</em></a>
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#t:callback_mode/0"><code class="inline">handle_event_function</code></a>. If a change
│ │ │ @@ -940,55 +940,55 @@
│ │ │    <a href="#selective-receive" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Selective Receive</span>
│ │ │  </h3>
│ │ │  <p>Erlang's selective <code class="inline">receive</code> statement is often used to describe simple state
│ │ │  machine examples in straightforward Erlang code. The following is a possible
│ │ │ -implementation of the first example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1186226203-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="1186226203-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1186226203-2">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_1</span><span class="p" data-group-id="1186226203-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1186226203-3">(</span><span class="p" data-group-id="1186226203-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="1186226203-4">]</span><span class="p" data-group-id="1186226203-3">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="1186226203-5">(</span><span class="n">Code</span><span class="p" data-group-id="1186226203-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">spawn</span><span class="p" data-group-id="1186226203-6">(</span><span class="w">
│ │ │ -      </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="1186226203-7">(</span><span class="p" data-group-id="1186226203-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">register</span><span class="p" data-group-id="1186226203-8">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="1186226203-9">(</span><span class="p" data-group-id="1186226203-9">)</span><span class="p" data-group-id="1186226203-8">)</span><span class="p">,</span><span class="w">
│ │ │ -	      </span><span class="nf">do_lock</span><span class="p" data-group-id="1186226203-10">(</span><span class="p" data-group-id="1186226203-10">)</span><span class="p">,</span><span class="w">
│ │ │ -	      </span><span class="nf">locked</span><span class="p" data-group-id="1186226203-11">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="1186226203-12">(</span><span class="n">Code</span><span class="p" data-group-id="1186226203-12">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1186226203-13">[</span><span class="p" data-group-id="1186226203-13">]</span><span class="p" data-group-id="1186226203-11">)</span><span class="w">
│ │ │ -      </span><span class="k">end</span><span class="p" data-group-id="1186226203-6">)</span><span class="p">.</span><span class="w">
│ │ │ +implementation of the first example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6598448637-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="6598448637-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="6598448637-2">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_1</span><span class="p" data-group-id="6598448637-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6598448637-3">(</span><span class="p" data-group-id="6598448637-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6598448637-4">]</span><span class="p" data-group-id="6598448637-3">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="6598448637-5">(</span><span class="n">Code</span><span class="p" data-group-id="6598448637-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">spawn</span><span class="p" data-group-id="6598448637-6">(</span><span class="w">
│ │ │ +      </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="6598448637-7">(</span><span class="p" data-group-id="6598448637-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +	      </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">register</span><span class="p" data-group-id="6598448637-8">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6598448637-9">(</span><span class="p" data-group-id="6598448637-9">)</span><span class="p" data-group-id="6598448637-8">)</span><span class="p">,</span><span class="w">
│ │ │ +	      </span><span class="nf">do_lock</span><span class="p" data-group-id="6598448637-10">(</span><span class="p" data-group-id="6598448637-10">)</span><span class="p">,</span><span class="w">
│ │ │ +	      </span><span class="nf">locked</span><span class="p" data-group-id="6598448637-11">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="6598448637-12">(</span><span class="n">Code</span><span class="p" data-group-id="6598448637-12">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6598448637-13">[</span><span class="p" data-group-id="6598448637-13">]</span><span class="p" data-group-id="6598448637-11">)</span><span class="w">
│ │ │ +      </span><span class="k">end</span><span class="p" data-group-id="6598448637-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">button</span><span class="p" data-group-id="1186226203-14">(</span><span class="n">Button</span><span class="p" data-group-id="1186226203-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="o">?</span><span class="n">NAME</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1186226203-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1186226203-15">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="4396325892-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="4396325892-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">button</span><span class="p" data-group-id="6598448637-14">(</span><span class="n">Button</span><span class="p" data-group-id="6598448637-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="o">?</span><span class="n">NAME</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6598448637-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6598448637-15">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="2242330624-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="2242330624-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4396325892-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="4396325892-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2242330624-2">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="2242330624-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │                  </span><span class="k">if</span><span class="w">
│ │ │ -                    </span><span class="nf">length</span><span class="p" data-group-id="4396325892-3">(</span><span class="n">Buttons</span><span class="p" data-group-id="4396325892-3">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                    </span><span class="nf">length</span><span class="p" data-group-id="2242330624-3">(</span><span class="n">Buttons</span><span class="p" data-group-id="2242330624-3">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                          </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │                      </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                        </span><span class="nf">tl</span><span class="p" data-group-id="4396325892-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="4396325892-4">)</span><span class="w">
│ │ │ -                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="4396325892-5">[</span><span class="n">Button</span><span class="p" data-group-id="4396325892-5">]</span><span class="p">,</span><span class="w">
│ │ │ +                        </span><span class="nf">tl</span><span class="p" data-group-id="2242330624-4">(</span><span class="n">Buttons</span><span class="p" data-group-id="2242330624-4">)</span><span class="w">
│ │ │ +                </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="2242330624-5">[</span><span class="n">Button</span><span class="p" data-group-id="2242330624-5">]</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="k">if</span><span class="w">
│ │ │                  </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="4396325892-6">(</span><span class="p" data-group-id="4396325892-6">)</span><span class="p">,</span><span class="w">
│ │ │ -		    </span><span class="nf">open</span><span class="p" data-group-id="4396325892-7">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="4396325892-7">)</span><span class="p">;</span><span class="w">
│ │ │ +                    </span><span class="nf">do_unlock</span><span class="p" data-group-id="2242330624-6">(</span><span class="p" data-group-id="2242330624-6">)</span><span class="p">,</span><span class="w">
│ │ │ +		    </span><span class="nf">open</span><span class="p" data-group-id="2242330624-7">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="2242330624-7">)</span><span class="p">;</span><span class="w">
│ │ │                  </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -                    </span><span class="nf">locked</span><span class="p" data-group-id="4396325892-8">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="4396325892-8">)</span><span class="w">
│ │ │ +                    </span><span class="nf">locked</span><span class="p" data-group-id="2242330624-8">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="2242330624-8">)</span><span class="w">
│ │ │              </span><span class="k">end</span><span class="w">
│ │ │ -    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="9352323651-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="9352323651-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">end</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="2346486148-1">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="2346486148-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -	    </span><span class="nf">do_lock</span><span class="p" data-group-id="9352323651-2">(</span><span class="p" data-group-id="9352323651-2">)</span><span class="p">,</span><span class="w">
│ │ │ -	    </span><span class="nf">locked</span><span class="p" data-group-id="9352323651-3">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9352323651-4">[</span><span class="p" data-group-id="9352323651-4">]</span><span class="p" data-group-id="9352323651-3">)</span><span class="w">
│ │ │ +	    </span><span class="nf">do_lock</span><span class="p" data-group-id="2346486148-2">(</span><span class="p" data-group-id="2346486148-2">)</span><span class="p">,</span><span class="w">
│ │ │ +	    </span><span class="nf">locked</span><span class="p" data-group-id="2346486148-3">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2346486148-4">[</span><span class="p" data-group-id="2346486148-4">]</span><span class="p" data-group-id="2346486148-3">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">do_lock</span><span class="p" data-group-id="9352323651-5">(</span><span class="p" data-group-id="9352323651-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9352323651-6">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9352323651-7">[</span><span class="p" data-group-id="9352323651-7">]</span><span class="p" data-group-id="9352323651-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="9352323651-8">(</span><span class="p" data-group-id="9352323651-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9352323651-9">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9352323651-10">[</span><span class="p" data-group-id="9352323651-10">]</span><span class="p" data-group-id="9352323651-9">)</span><span class="p">.</span></code></pre><p>The selective receive in this case causes <code class="inline">open</code> to implicitly postpone any
│ │ │ +</span><span class="nf">do_lock</span><span class="p" data-group-id="2346486148-5">(</span><span class="p" data-group-id="2346486148-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2346486148-6">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2346486148-7">[</span><span class="p" data-group-id="2346486148-7">]</span><span class="p" data-group-id="2346486148-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="2346486148-8">(</span><span class="p" data-group-id="2346486148-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="2346486148-9">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2346486148-10">[</span><span class="p" data-group-id="2346486148-10">]</span><span class="p" data-group-id="2346486148-9">)</span><span class="p">.</span></code></pre><p>The selective receive in this case causes <code class="inline">open</code> to implicitly postpone any
│ │ │  events to the <code class="inline">locked</code> state.</p><p>A catch-all receive should never be used from a <code class="inline">gen_statem</code> behaviour
│ │ │  (or from any <code class="inline">gen_*</code> behaviour), as the receive statement is within
│ │ │  the <code class="inline">gen_*</code> engine itself. <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html"><code class="inline">sys</code></a>-compatible behaviours must respond to
│ │ │  system messages and therefore do that in their engine receive loop,
│ │ │  passing non-system messages to the <em>callback module</em>. Using a catch-all
│ │ │  receive can result in system messages being discarded, which in turn
│ │ │  can lead to unexpected behaviour. If a selective receive must be used,
│ │ │ @@ -1011,40 +1011,40 @@
│ │ │  section), especially if only one or a few states have state enter actions,
│ │ │  this is a perfect use case for the built in
│ │ │  <a href="#state-enter-calls"><em>state enter calls</em></a>.</p><p>You return a list containing <code class="inline">state_enter</code> from your
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#c:callback_mode/0"><code class="inline">callback_mode/0</code></a> function and the
│ │ │  <code class="inline">gen_statem</code> engine will call your <em>state callback</em> once with an event
│ │ │  <code class="inline">(enter, OldState, ...)</code> whenever it does a <em>state change</em>. Then you
│ │ │  just need to handle these event-like calls in all states.</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="8634867505-1">(</span><span class="n">Code</span><span class="p" data-group-id="8634867505-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="8634867505-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="8634867505-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8634867505-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="8634867505-4">(</span><span class="n">Code</span><span class="p" data-group-id="8634867505-4">)</span><span class="p" data-group-id="8634867505-3">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8634867505-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8634867505-5">}</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="8634867505-6">(</span><span class="p" data-group-id="8634867505-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8634867505-7">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="8634867505-7">]</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="8634867505-8">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8634867505-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="8634867505-9">(</span><span class="p" data-group-id="8634867505-9">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8634867505-10">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="8634867505-11">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8634867505-12">[</span><span class="p" data-group-id="8634867505-12">]</span><span class="p" data-group-id="8634867505-11">}</span><span class="p" data-group-id="8634867505-10">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="8634867505-13">(</span><span class="w">
│ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8634867505-14">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8634867505-14">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8634867505-15">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="8634867505-15">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8634867505-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="9027935050-1">(</span><span class="n">Code</span><span class="p" data-group-id="9027935050-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="9027935050-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="9027935050-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9027935050-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="9027935050-4">(</span><span class="n">Code</span><span class="p" data-group-id="9027935050-4">)</span><span class="p" data-group-id="9027935050-3">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9027935050-5">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9027935050-5">}</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="9027935050-6">(</span><span class="p" data-group-id="9027935050-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9027935050-7">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="9027935050-7">]</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="9027935050-8">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9027935050-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="9027935050-9">(</span><span class="p" data-group-id="9027935050-9">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9027935050-10">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="9027935050-11">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9027935050-12">[</span><span class="p" data-group-id="9027935050-12">]</span><span class="p" data-group-id="9027935050-11">}</span><span class="p" data-group-id="9027935050-10">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="9027935050-13">(</span><span class="w">
│ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9027935050-14">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9027935050-14">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="9027935050-15">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="9027935050-15">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9027935050-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="8634867505-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8634867505-16">}</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9027935050-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9027935050-16">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="8634867505-17">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="8634867505-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="8634867505-18">(</span><span class="p" data-group-id="8634867505-18">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8634867505-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="8634867505-20">[</span><span class="p" data-group-id="8634867505-21">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="8634867505-21">}</span><span class="p" data-group-id="8634867505-20">]</span><span class="p" data-group-id="8634867505-19">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="8634867505-22">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8634867505-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8634867505-23">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8634867505-23">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="9027935050-17">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="9027935050-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="9027935050-18">(</span><span class="p" data-group-id="9027935050-18">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9027935050-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="9027935050-20">[</span><span class="p" data-group-id="9027935050-21">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="9027935050-21">}</span><span class="p" data-group-id="9027935050-20">]</span><span class="p" data-group-id="9027935050-19">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="9027935050-22">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9027935050-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9027935050-23">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9027935050-23">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>You can repeat the state enter code by returning one of
│ │ │  <code class="inline">{repeat_state, ...}</code>,<code class="inline">{repeat_state_and_data, _}</code>,
│ │ │  or <code class="inline">repeat_state_and_data</code> that otherwise behaves exactly like their
│ │ │  <code class="inline">keep_state</code> siblings.  See the type
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#t:state_callback_result/2"><code class="inline">state_callback_result()</code></a>
│ │ │  in the Reference Manual.</p><h2 id="inserted-events" class="section-heading">
│ │ │    <a href="#inserted-events" class="hover-link">
│ │ │ @@ -1066,44 +1066,44 @@
│ │ │  to dispatch pre-processed events as internal events to the main state
│ │ │  machine.</p><p>Using internal events also can make it easier to synchronize the state
│ │ │  machines.</p><p>A variant of this is to use a <a href="#complex-state">complex state</a> with
│ │ │  <a href="#one-state-callback">one state callback</a>, modeling the state
│ │ │  with, for example, a tuple <code class="inline">{MainFSMState, SubFSMState}</code>.</p><p>To illustrate this we make up an example where the buttons instead generate
│ │ │  down and up (press and release) events, and the lock responds
│ │ │  to an up event only after the corresponding down event.</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6727326059-1">(</span><span class="p" data-group-id="6727326059-2">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="6727326059-2">]</span><span class="p" data-group-id="6727326059-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7934251671-1">(</span><span class="p" data-group-id="7934251671-2">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7934251671-2">]</span><span class="p" data-group-id="7934251671-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">down</span><span class="p" data-group-id="6727326059-3">(</span><span class="n">Button</span><span class="p" data-group-id="6727326059-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="6727326059-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6727326059-5">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6727326059-5">}</span><span class="p" data-group-id="6727326059-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">down</span><span class="p" data-group-id="7934251671-3">(</span><span class="n">Button</span><span class="p" data-group-id="7934251671-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="7934251671-4">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7934251671-5">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7934251671-5">}</span><span class="p" data-group-id="7934251671-4">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">up</span><span class="p" data-group-id="6727326059-6">(</span><span class="n">Button</span><span class="p" data-group-id="6727326059-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="6727326059-7">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6727326059-8">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6727326059-8">}</span><span class="p" data-group-id="6727326059-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">up</span><span class="p" data-group-id="7934251671-6">(</span><span class="n">Button</span><span class="p" data-group-id="7934251671-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="7934251671-7">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7934251671-8">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7934251671-8">}</span><span class="p" data-group-id="7934251671-7">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="6727326059-9">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6727326059-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="6727326059-10">(</span><span class="p" data-group-id="6727326059-10">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6727326059-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="6727326059-12">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6727326059-13">[</span><span class="p" data-group-id="6727326059-13">]</span><span class="p" data-group-id="6727326059-12">}</span><span class="p" data-group-id="6727326059-11">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="6727326059-14">(</span><span class="w">
│ │ │ -  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6727326059-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6727326059-15">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="6727326059-16">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="6727326059-16">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6727326059-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">handle_common</span><span class="p" data-group-id="6777023298-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6777023298-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6777023298-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6777023298-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6777023298-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6777023298-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="6777023298-4">}</span><span class="p" data-group-id="6777023298-3">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="6777023298-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6777023298-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6777023298-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6777023298-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="7934251671-9">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7934251671-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="7934251671-10">(</span><span class="p" data-group-id="7934251671-10">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7934251671-11">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="7934251671-12">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7934251671-13">[</span><span class="p" data-group-id="7934251671-13">]</span><span class="p" data-group-id="7934251671-12">}</span><span class="p" data-group-id="7934251671-11">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="7934251671-14">(</span><span class="w">
│ │ │ +  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7934251671-15">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7934251671-15">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7934251671-16">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="7934251671-16">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7934251671-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">handle_common</span><span class="p" data-group-id="7304071276-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7304071276-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7304071276-2">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7304071276-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7304071276-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7304071276-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="7304071276-4">}</span><span class="p" data-group-id="7304071276-3">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="7304071276-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7304071276-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7304071276-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7304071276-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Data</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="6777023298-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="6777023298-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="6777023298-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="6777023298-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6777023298-9">)</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="6777023298-10">[</span><span class="p" data-group-id="6777023298-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="6777023298-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6777023298-12">}</span><span class="p" data-group-id="6777023298-11">}</span><span class="p" data-group-id="6777023298-10">]</span><span class="p" data-group-id="6777023298-8">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="6777023298-13">#{</span><span class="p" data-group-id="6777023298-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="7304071276-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="7304071276-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="7304071276-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="7304071276-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7304071276-9">)</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="7304071276-10">[</span><span class="p" data-group-id="7304071276-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="7304071276-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7304071276-12">}</span><span class="p" data-group-id="7304071276-11">}</span><span class="p" data-group-id="7304071276-10">]</span><span class="p" data-group-id="7304071276-8">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="7304071276-13">#{</span><span class="p" data-group-id="7304071276-13">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="6777023298-14">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6777023298-15">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6777023298-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6777023298-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6777023298-16">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="6777023298-17">[</span><span class="ss">postpone</span><span class="p" data-group-id="6777023298-17">]</span><span class="p" data-group-id="6777023298-16">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="7304071276-14">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7304071276-15">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7304071276-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7304071276-14">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7304071276-16">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="n">Data</span><span class="p">,</span><span class="p" data-group-id="7304071276-17">[</span><span class="ss">postpone</span><span class="p" data-group-id="7304071276-17">]</span><span class="p" data-group-id="7304071276-16">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>If you start this program with <code class="inline">code_lock:start([17])</code> you can unlock with
│ │ │  <code class="inline">code_lock:down(17), code_lock:up(17).</code></p><h2 id="example-revisited" class="section-heading">
│ │ │    <a href="#example-revisited" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Example Revisited</span>
│ │ │  </h2>
│ │ │ @@ -1131,152 +1131,152 @@
│ │ │  Also, the state diagram does not show that the <code class="inline">code_length/0</code> call
│ │ │  must be handled in every state.</p><h3 id="callback-mode-state_functions" class="section-heading">
│ │ │    <a href="#callback-mode-state_functions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Callback Mode: state_functions</span>
│ │ │  </h3>
│ │ │ -<p>Using state functions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9434476206-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="9434476206-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9434476206-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="9434476206-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9434476206-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_2</span><span class="p" data-group-id="9434476206-3">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Using state functions:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8842464718-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="8842464718-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="8842464718-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="8842464718-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="8842464718-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_2</span><span class="p" data-group-id="8842464718-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9434476206-4">(</span><span class="p" data-group-id="9434476206-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9434476206-5">]</span><span class="p" data-group-id="9434476206-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9434476206-6">(</span><span class="p" data-group-id="9434476206-7">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9434476206-7">]</span><span class="p" data-group-id="9434476206-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9434476206-8">(</span><span class="p" data-group-id="9434476206-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="9434476206-9">]</span><span class="p" data-group-id="9434476206-8">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9434476206-10">(</span><span class="p" data-group-id="9434476206-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="9434476206-11">]</span><span class="p" data-group-id="9434476206-10">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="9434476206-12">(</span><span class="n">Code</span><span class="p" data-group-id="9434476206-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9434476206-13">(</span><span class="p" data-group-id="9434476206-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="9434476206-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9434476206-15">[</span><span class="p" data-group-id="9434476206-15">]</span><span class="p" data-group-id="9434476206-13">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="9434476206-16">(</span><span class="p" data-group-id="9434476206-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="9434476206-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="9434476206-17">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">down</span><span class="p" data-group-id="9434476206-18">(</span><span class="n">Button</span><span class="p" data-group-id="9434476206-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="9434476206-19">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9434476206-20">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9434476206-20">}</span><span class="p" data-group-id="9434476206-19">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">up</span><span class="p" data-group-id="9434476206-21">(</span><span class="n">Button</span><span class="p" data-group-id="9434476206-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="9434476206-22">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9434476206-23">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9434476206-23">}</span><span class="p" data-group-id="9434476206-22">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">code_length</span><span class="p" data-group-id="9434476206-24">(</span><span class="p" data-group-id="9434476206-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="9434476206-25">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="9434476206-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="9018714236-1">(</span><span class="n">Code</span><span class="p" data-group-id="9018714236-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="9018714236-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="9018714236-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9018714236-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="9018714236-4">(</span><span class="n">Code</span><span class="p" data-group-id="9018714236-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9018714236-5">[</span><span class="p" data-group-id="9018714236-5">]</span><span class="p" data-group-id="9018714236-3">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9018714236-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9018714236-6">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8842464718-4">(</span><span class="p" data-group-id="8842464718-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8842464718-5">]</span><span class="p" data-group-id="8842464718-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8842464718-6">(</span><span class="p" data-group-id="8842464718-7">[</span><span class="ss">down</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">up</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">code_length</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8842464718-7">]</span><span class="p" data-group-id="8842464718-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8842464718-8">(</span><span class="p" data-group-id="8842464718-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="8842464718-9">]</span><span class="p" data-group-id="8842464718-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8842464718-10">(</span><span class="p" data-group-id="8842464718-11">[</span><span class="ss">locked</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">open</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="8842464718-11">]</span><span class="p" data-group-id="8842464718-10">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="8842464718-12">(</span><span class="n">Code</span><span class="p" data-group-id="8842464718-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8842464718-13">(</span><span class="p" data-group-id="8842464718-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="8842464718-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8842464718-15">[</span><span class="p" data-group-id="8842464718-15">]</span><span class="p" data-group-id="8842464718-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="8842464718-16">(</span><span class="p" data-group-id="8842464718-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="8842464718-17">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="8842464718-17">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">down</span><span class="p" data-group-id="8842464718-18">(</span><span class="n">Button</span><span class="p" data-group-id="8842464718-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="8842464718-19">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8842464718-20">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8842464718-20">}</span><span class="p" data-group-id="8842464718-19">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">up</span><span class="p" data-group-id="8842464718-21">(</span><span class="n">Button</span><span class="p" data-group-id="8842464718-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="8842464718-22">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8842464718-23">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8842464718-23">}</span><span class="p" data-group-id="8842464718-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">code_length</span><span class="p" data-group-id="8842464718-24">(</span><span class="p" data-group-id="8842464718-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="8842464718-25">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p" data-group-id="8842464718-25">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="3253433827-1">(</span><span class="n">Code</span><span class="p" data-group-id="3253433827-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="3253433827-2">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3253433827-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3253433827-3">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="3253433827-4">(</span><span class="n">Code</span><span class="p" data-group-id="3253433827-4">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3253433827-5">[</span><span class="p" data-group-id="3253433827-5">]</span><span class="p" data-group-id="3253433827-3">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3253433827-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3253433827-6">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="9018714236-7">(</span><span class="p" data-group-id="9018714236-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9018714236-8">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="9018714236-8">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="3253433827-7">(</span><span class="p" data-group-id="3253433827-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3253433827-8">[</span><span class="ss">state_functions</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="3253433827-8">]</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9018714236-9">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="9018714236-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="9018714236-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="9018714236-11">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="9018714236-11">)</span><span class="p" data-group-id="9018714236-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="3253433827-9">(</span><span class="n">HANDLE_COMMON</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="o">?</span><span class="n">FUNCTION_NAME</span><span class="p" data-group-id="3253433827-10">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="3253433827-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">handle_common</span><span class="p" data-group-id="3253433827-11">(</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">C</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="3253433827-11">)</span><span class="p" data-group-id="3253433827-9">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="9018714236-12">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9018714236-13">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9018714236-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9018714236-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9018714236-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9018714236-15">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="9018714236-15">}</span><span class="p" data-group-id="9018714236-14">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="9018714236-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9018714236-17">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9018714236-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9018714236-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="3253433827-12">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3253433827-13">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="3253433827-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3253433827-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3253433827-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3253433827-15">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="3253433827-15">}</span><span class="p" data-group-id="3253433827-14">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="3253433827-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3253433827-17">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="3253433827-17">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3253433827-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Data</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="9018714236-18">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="9018714236-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="9018714236-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="9018714236-20">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9018714236-20">)</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="9018714236-21">[</span><span class="p" data-group-id="9018714236-22">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="9018714236-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9018714236-23">}</span><span class="p" data-group-id="9018714236-22">}</span><span class="p" data-group-id="9018714236-21">]</span><span class="p" data-group-id="9018714236-19">}</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="9018714236-24">#{</span><span class="p" data-group-id="9018714236-24">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="3253433827-18">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="3253433827-18">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="3253433827-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="3253433827-20">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="3253433827-20">)</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="3253433827-21">[</span><span class="p" data-group-id="3253433827-22">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="3253433827-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="3253433827-23">}</span><span class="p" data-group-id="3253433827-22">}</span><span class="p" data-group-id="3253433827-21">]</span><span class="p" data-group-id="3253433827-19">}</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="3253433827-24">#{</span><span class="p" data-group-id="3253433827-24">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_common</span><span class="p" data-group-id="9018714236-25">(</span><span class="p" data-group-id="9018714236-26">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="9018714236-26">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9018714236-27">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="9018714236-27">}</span><span class="p" data-group-id="9018714236-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9018714236-28">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="9018714236-29">[</span><span class="p" data-group-id="9018714236-30">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="9018714236-31">(</span><span class="n">Code</span><span class="p" data-group-id="9018714236-31">)</span><span class="p" data-group-id="9018714236-30">}</span><span class="p" data-group-id="9018714236-29">]</span><span class="p" data-group-id="9018714236-28">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="8667524697-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8667524697-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="8667524697-2">(</span><span class="p" data-group-id="8667524697-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8667524697-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8667524697-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="8667524697-5">[</span><span class="p" data-group-id="8667524697-5">]</span><span class="p" data-group-id="8667524697-4">}</span><span class="p" data-group-id="8667524697-3">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="8667524697-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8667524697-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8667524697-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8667524697-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="8667524697-9">[</span><span class="p" data-group-id="8667524697-9">]</span><span class="p" data-group-id="8667524697-8">}</span><span class="p" data-group-id="8667524697-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">locked</span><span class="p" data-group-id="8667524697-10">(</span><span class="w">
│ │ │ -  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8667524697-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="8667524697-11">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="8667524697-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="8667524697-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8667524697-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_common</span><span class="p" data-group-id="3253433827-25">(</span><span class="p" data-group-id="3253433827-26">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="3253433827-26">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3253433827-27">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="3253433827-27">}</span><span class="p" data-group-id="3253433827-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3253433827-28">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="3253433827-29">[</span><span class="p" data-group-id="3253433827-30">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="nf">length</span><span class="p" data-group-id="3253433827-31">(</span><span class="n">Code</span><span class="p" data-group-id="3253433827-31">)</span><span class="p" data-group-id="3253433827-30">}</span><span class="p" data-group-id="3253433827-29">]</span><span class="p" data-group-id="3253433827-28">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">locked</span><span class="p" data-group-id="6430901450-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6430901450-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="6430901450-2">(</span><span class="p" data-group-id="6430901450-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6430901450-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6430901450-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6430901450-5">[</span><span class="p" data-group-id="6430901450-5">]</span><span class="p" data-group-id="6430901450-4">}</span><span class="p" data-group-id="6430901450-3">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="6430901450-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6430901450-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6430901450-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6430901450-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6430901450-9">[</span><span class="p" data-group-id="6430901450-9">]</span><span class="p" data-group-id="6430901450-8">}</span><span class="p" data-group-id="6430901450-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">locked</span><span class="p" data-group-id="6430901450-10">(</span><span class="w">
│ │ │ +  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6430901450-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6430901450-11">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="6430901450-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="6430901450-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6430901450-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │          </span><span class="k">if</span><span class="w">
│ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="8667524697-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="8667524697-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="6430901450-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="6430901450-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="8667524697-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="8667524697-14">)</span><span class="w">
│ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="8667524697-15">[</span><span class="n">Button</span><span class="p" data-group-id="8667524697-15">]</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="6430901450-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="6430901450-14">)</span><span class="w">
│ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6430901450-15">[</span><span class="n">Button</span><span class="p" data-group-id="6430901450-15">]</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="8667524697-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8667524697-16">}</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6430901450-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6430901450-16">}</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="8667524697-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="8667524697-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="8667524697-18">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="8667524697-19">[</span><span class="p" data-group-id="8667524697-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="8667524697-20">}</span><span class="p" data-group-id="8667524697-19">]</span><span class="p" data-group-id="8667524697-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6430901450-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6430901450-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="6430901450-18">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="6430901450-19">[</span><span class="p" data-group-id="6430901450-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="6430901450-20">}</span><span class="p" data-group-id="6430901450-19">]</span><span class="p" data-group-id="6430901450-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="4812709100-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="4812709100-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="4812709100-2">(</span><span class="p" data-group-id="4812709100-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4812709100-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="4812709100-4">[</span><span class="p" data-group-id="4812709100-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="4812709100-5">}</span><span class="p" data-group-id="4812709100-4">]</span><span class="p" data-group-id="4812709100-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="4812709100-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4812709100-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4812709100-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4812709100-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">open</span><span class="p" data-group-id="4812709100-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4812709100-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4812709100-9">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="4812709100-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4812709100-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4812709100-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="4812709100-11">]</span><span class="p" data-group-id="4812709100-10">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">open</span><span class="p" data-group-id="7450153101-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="7450153101-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="7450153101-2">(</span><span class="p" data-group-id="7450153101-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7450153101-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="7450153101-4">[</span><span class="p" data-group-id="7450153101-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="7450153101-5">}</span><span class="p" data-group-id="7450153101-4">]</span><span class="p" data-group-id="7450153101-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="7450153101-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7450153101-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7450153101-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7450153101-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">open</span><span class="p" data-group-id="7450153101-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7450153101-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="7450153101-9">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7450153101-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7450153101-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7450153101-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="7450153101-11">]</span><span class="p" data-group-id="7450153101-10">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="o">?</span><span class="n">HANDLE_COMMON</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">do_lock</span><span class="p" data-group-id="4812709100-12">(</span><span class="p" data-group-id="4812709100-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4812709100-13">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4812709100-14">[</span><span class="p" data-group-id="4812709100-14">]</span><span class="p" data-group-id="4812709100-13">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="4812709100-15">(</span><span class="p" data-group-id="4812709100-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4812709100-16">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4812709100-17">[</span><span class="p" data-group-id="4812709100-17">]</span><span class="p" data-group-id="4812709100-16">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">do_lock</span><span class="p" data-group-id="7450153101-12">(</span><span class="p" data-group-id="7450153101-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7450153101-13">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7450153101-14">[</span><span class="p" data-group-id="7450153101-14">]</span><span class="p" data-group-id="7450153101-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="7450153101-15">(</span><span class="p" data-group-id="7450153101-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="7450153101-16">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7450153101-17">[</span><span class="p" data-group-id="7450153101-17">]</span><span class="p" data-group-id="7450153101-16">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="4812709100-18">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="4812709100-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="4812709100-19">(</span><span class="p" data-group-id="4812709100-19">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="7450153101-18">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="7450153101-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="7450153101-19">(</span><span class="p" data-group-id="7450153101-19">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h3 id="callback-mode-handle_event_function" class="section-heading">
│ │ │    <a href="#callback-mode-handle_event_function" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Callback Mode: handle_event_function</span>
│ │ │  </h3>
│ │ │  <p>This section describes what to change in the example to use one
│ │ │  <code class="inline">handle_event/4</code> function.  The previously used approach to first branch
│ │ │  depending on event does not work that well here because of
│ │ │ -the <em>state enter calls</em>, so this example first branches depending on state:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5141317744-1">(</span><span class="p" data-group-id="5141317744-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="5141317744-2">]</span><span class="p" data-group-id="5141317744-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="1838347277-1">(</span><span class="p" data-group-id="1838347277-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1838347277-2">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="1838347277-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ +the <em>state enter calls</em>, so this example first branches depending on state:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8834848743-1">(</span><span class="p" data-group-id="8834848743-2">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="8834848743-2">]</span><span class="p" data-group-id="8834848743-1">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">callback_mode</span><span class="p" data-group-id="5699724673-1">(</span><span class="p" data-group-id="5699724673-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5699724673-2">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="5699724673-2">]</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │  </span><span class="c1">%% State: locked</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="9808760629-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9808760629-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="9808760629-2">(</span><span class="p" data-group-id="9808760629-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9808760629-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9808760629-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9808760629-5">[</span><span class="p" data-group-id="9808760629-5">]</span><span class="p" data-group-id="9808760629-4">}</span><span class="p" data-group-id="9808760629-3">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="9808760629-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9808760629-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9808760629-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9808760629-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="9808760629-9">[</span><span class="p" data-group-id="9808760629-9">]</span><span class="p" data-group-id="9808760629-8">}</span><span class="p" data-group-id="9808760629-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="9808760629-10">(</span><span class="w">
│ │ │ -  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9808760629-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="9808760629-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9808760629-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="9808760629-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9808760629-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="7009753662-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7009753662-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="7009753662-2">(</span><span class="p" data-group-id="7009753662-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7009753662-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7009753662-4">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="7009753662-5">[</span><span class="p" data-group-id="7009753662-5">]</span><span class="p" data-group-id="7009753662-4">}</span><span class="p" data-group-id="7009753662-3">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="7009753662-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7009753662-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7009753662-7">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7009753662-8">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="7009753662-9">[</span><span class="p" data-group-id="7009753662-9">]</span><span class="p" data-group-id="7009753662-8">}</span><span class="p" data-group-id="7009753662-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="7009753662-10">(</span><span class="w">
│ │ │ +  </span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7009753662-11">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7009753662-11">}</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="7009753662-12">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="7009753662-12">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7009753662-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │          </span><span class="k">if</span><span class="w">
│ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="9808760629-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="9808760629-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="7009753662-13">(</span><span class="n">Buttons</span><span class="p" data-group-id="7009753662-13">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="9808760629-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="9808760629-14">)</span><span class="w">
│ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="9808760629-15">[</span><span class="n">Button</span><span class="p" data-group-id="9808760629-15">]</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="7009753662-14">(</span><span class="n">Buttons</span><span class="p" data-group-id="7009753662-14">)</span><span class="w">
│ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="7009753662-15">[</span><span class="n">Button</span><span class="p" data-group-id="7009753662-15">]</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="9808760629-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9808760629-16">}</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="7009753662-16">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7009753662-16">}</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="9808760629-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9808760629-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="9808760629-18">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="9808760629-19">[</span><span class="p" data-group-id="9808760629-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="9808760629-20">}</span><span class="p" data-group-id="9808760629-19">]</span><span class="p" data-group-id="9808760629-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="7009753662-17">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7009753662-18">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="7009753662-18">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="7009753662-19">[</span><span class="p" data-group-id="7009753662-20">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="7009753662-20">}</span><span class="p" data-group-id="7009753662-19">]</span><span class="p" data-group-id="7009753662-17">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │  </span><span class="c1">%% State: open</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4883667589-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="4883667589-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="4883667589-2">(</span><span class="p" data-group-id="4883667589-2">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4883667589-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="4883667589-4">[</span><span class="p" data-group-id="4883667589-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="4883667589-5">}</span><span class="p" data-group-id="4883667589-4">]</span><span class="p" data-group-id="4883667589-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4883667589-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4883667589-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4883667589-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4883667589-7">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="4883667589-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4883667589-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4883667589-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="4883667589-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4883667589-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="4883667589-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="4883667589-11">]</span><span class="p" data-group-id="4883667589-10">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%% Common events</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="5072292545-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5072292545-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5072292545-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5072292545-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5072292545-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5072292545-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="5072292545-4">}</span><span class="p" data-group-id="5072292545-3">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="5072292545-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5072292545-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5072292545-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5072292545-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="0064007853-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="0064007853-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="0064007853-2">(</span><span class="p" data-group-id="0064007853-2">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0064007853-3">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="0064007853-4">[</span><span class="p" data-group-id="0064007853-5">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="0064007853-5">}</span><span class="p" data-group-id="0064007853-4">]</span><span class="p" data-group-id="0064007853-3">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="0064007853-6">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0064007853-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0064007853-7">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="ss">locked</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0064007853-7">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="0064007853-8">(</span><span class="ss">internal</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0064007853-9">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0064007853-9">}</span><span class="p">,</span><span class="w"> </span><span class="ss">open</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="0064007853-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0064007853-10">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="0064007853-11">[</span><span class="ss">postpone</span><span class="p" data-group-id="0064007853-11">]</span><span class="p" data-group-id="0064007853-10">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%% Common events</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="1451353353-1">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1451353353-2">{</span><span class="ss">down</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1451353353-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1451353353-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1451353353-3">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1451353353-4">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="1451353353-4">}</span><span class="p" data-group-id="1451353353-3">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="1451353353-5">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1451353353-6">{</span><span class="ss">up</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1451353353-6">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1451353353-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Data</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5072292545-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="5072292545-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="5072292545-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="5072292545-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5072292545-9">)</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="5072292545-10">[</span><span class="p" data-group-id="5072292545-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="5072292545-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5072292545-12">}</span><span class="p" data-group-id="5072292545-11">}</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="5072292545-13">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="5072292545-13">}</span><span class="p" data-group-id="5072292545-10">]</span><span class="p" data-group-id="5072292545-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5072292545-14">#{</span><span class="p" data-group-id="5072292545-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1451353353-7">#{</span><span class="ss">button</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Button</span><span class="p" data-group-id="1451353353-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="1451353353-8">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">remove</span><span class="p" data-group-id="1451353353-9">(</span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1451353353-9">)</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="1451353353-10">[</span><span class="p" data-group-id="1451353353-11">{</span><span class="ss">next_event</span><span class="p">,</span><span class="ss">internal</span><span class="p">,</span><span class="p" data-group-id="1451353353-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="1451353353-12">}</span><span class="p" data-group-id="1451353353-11">}</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="1451353353-13">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="1451353353-13">}</span><span class="p" data-group-id="1451353353-10">]</span><span class="p" data-group-id="1451353353-8">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1451353353-14">#{</span><span class="p" data-group-id="1451353353-14">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">keep_state_and_data</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="5072292545-15">(</span><span class="p" data-group-id="5072292545-16">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="5072292545-16">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5072292545-17">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="5072292545-17">}</span><span class="p" data-group-id="5072292545-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5072292545-18">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="5072292545-19">[</span><span class="p" data-group-id="5072292545-20">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">Length</span><span class="p" data-group-id="5072292545-20">}</span><span class="p" data-group-id="5072292545-19">]</span><span class="p" data-group-id="5072292545-18">}</span><span class="p">.</span></code></pre><p>Notice that postponing buttons from the <code class="inline">open</code> state to the <code class="inline">locked</code> state
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="1451353353-15">(</span><span class="p" data-group-id="1451353353-16">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="1451353353-16">}</span><span class="p">,</span><span class="w"> </span><span class="ss">code_length</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1451353353-17">#{</span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="1451353353-17">}</span><span class="p" data-group-id="1451353353-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1451353353-18">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="1451353353-19">[</span><span class="p" data-group-id="1451353353-20">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">Length</span><span class="p" data-group-id="1451353353-20">}</span><span class="p" data-group-id="1451353353-19">]</span><span class="p" data-group-id="1451353353-18">}</span><span class="p">.</span></code></pre><p>Notice that postponing buttons from the <code class="inline">open</code> state to the <code class="inline">locked</code> state
│ │ │  seems like a strange thing to do for a code lock, but it at least
│ │ │  illustrates event postponing.</p><h2 id="filter-the-state" class="section-heading">
│ │ │    <a href="#filter-the-state" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Filter the State</span>
│ │ │  </h2>
│ │ │ @@ -1286,30 +1286,30 @@
│ │ │  and which digits that remain to unlock.</p><p>This state data can be regarded as sensitive, and maybe not what you want
│ │ │  in the error log because of some unpredictable event.</p><p>Another reason to filter the state can be that the state is too large to print,
│ │ │  as it fills the error log with uninteresting details.</p><p>To avoid this, you can format the internal state that gets in the error log
│ │ │  and gets returned from <a href="../../lib/stdlib-6.2.2.2/doc/html/sys.html#get_status/1"><code class="inline">sys:get_status/1,2</code></a>
│ │ │  by implementing function
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#c:format_status/2"><code class="inline">Module:format_status/2</code></a>,
│ │ │  for example like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7614304736-1">(</span><span class="p" data-group-id="7614304736-2">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">format_status</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7614304736-2">]</span><span class="p" data-group-id="7614304736-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9228006981-1">(</span><span class="p" data-group-id="9228006981-2">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="ss">format_status</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9228006981-2">]</span><span class="p" data-group-id="9228006981-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">format_status</span><span class="p" data-group-id="7614304736-3">(</span><span class="n">Opt</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7614304736-4">[</span><span class="p">_</span><span class="n">PDict</span><span class="p">,</span><span class="n">State</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="7614304736-4">]</span><span class="p" data-group-id="7614304736-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">format_status</span><span class="p" data-group-id="9228006981-3">(</span><span class="n">Opt</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9228006981-4">[</span><span class="p">_</span><span class="n">PDict</span><span class="p">,</span><span class="n">State</span><span class="p">,</span><span class="n">Data</span><span class="p" data-group-id="9228006981-4">]</span><span class="p" data-group-id="9228006981-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">StateData</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ -	</span><span class="p" data-group-id="7614304736-5">{</span><span class="n">State</span><span class="p">,</span><span class="w">
│ │ │ -	 </span><span class="nc">maps</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="7614304736-6">(</span><span class="w">
│ │ │ -	   </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="7614304736-7">(</span><span class="ss">code</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7614304736-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="p">;</span><span class="w">
│ │ │ -	       </span><span class="p" data-group-id="7614304736-8">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7614304736-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="w">
│ │ │ +	</span><span class="p" data-group-id="9228006981-5">{</span><span class="n">State</span><span class="p">,</span><span class="w">
│ │ │ +	 </span><span class="nc">maps</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="9228006981-6">(</span><span class="w">
│ │ │ +	   </span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="9228006981-7">(</span><span class="ss">code</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9228006981-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">false</span><span class="p">;</span><span class="w">
│ │ │ +	       </span><span class="p" data-group-id="9228006981-8">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="9228006981-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">true</span><span class="w">
│ │ │  	   </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -	   </span><span class="n">Data</span><span class="p" data-group-id="7614304736-6">)</span><span class="p" data-group-id="7614304736-5">}</span><span class="p">,</span><span class="w">
│ │ │ +	   </span><span class="n">Data</span><span class="p" data-group-id="9228006981-6">)</span><span class="p" data-group-id="9228006981-5">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">Opt</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │  	</span><span class="ss">terminate</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  	    </span><span class="n">StateData</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">normal</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -	    </span><span class="p" data-group-id="7614304736-9">[</span><span class="p" data-group-id="7614304736-10">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="7614304736-11">[</span><span class="p" data-group-id="7614304736-12">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="n">StateData</span><span class="p" data-group-id="7614304736-12">}</span><span class="p" data-group-id="7614304736-11">]</span><span class="p" data-group-id="7614304736-10">}</span><span class="p" data-group-id="7614304736-9">]</span><span class="w">
│ │ │ +	    </span><span class="p" data-group-id="9228006981-9">[</span><span class="p" data-group-id="9228006981-10">{</span><span class="ss">data</span><span class="p">,</span><span class="p" data-group-id="9228006981-11">[</span><span class="p" data-group-id="9228006981-12">{</span><span class="s">&quot;State&quot;</span><span class="p">,</span><span class="n">StateData</span><span class="p" data-group-id="9228006981-12">}</span><span class="p" data-group-id="9228006981-11">]</span><span class="p" data-group-id="9228006981-10">}</span><span class="p" data-group-id="9228006981-9">]</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>It is not mandatory to implement a
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#c:format_status/2"><code class="inline">Module:format_status/2</code></a> function.
│ │ │  If you do not, a default implementation is used that does the same
│ │ │  as this example function without filtering the <code class="inline">Data</code> term, that is,
│ │ │  <code class="inline">StateData = {State, Data}</code>, in this example containing sensitive information.</p><h2 id="complex-state" class="section-heading">
│ │ │    <a href="#complex-state" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -1322,104 +1322,104 @@
│ │ │  like a tuple.</p><p>One reason to use this is when you have a state item that when changed
│ │ │  should cancel the <a href="#state-time-outs"><em>state time-out</em></a>, or one that affects
│ │ │  the event handling in combination with postponing events. We will go for
│ │ │  the latter and complicate the previous example by introducing
│ │ │  a configurable lock button (this is the state item in question),
│ │ │  which in the <code class="inline">open</code> state immediately locks the door, and an API function
│ │ │  <code class="inline">set_lock_button/1</code> to set the lock button.</p><p>Suppose now that we call <code class="inline">set_lock_button</code> while the door is open,
│ │ │ -and we have already postponed a button event that was the new lock button:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9070980681-1">(</span><span class="p" data-group-id="9070980681-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="9070980681-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">x</span><span class="p" data-group-id="9070980681-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9070980681-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.666</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="9070980681-3">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="9070980681-4">(</span><span class="ss">a</span><span class="p" data-group-id="9070980681-4">)</span><span class="p">.</span><span class="w">
│ │ │ +and we have already postponed a button event that was the new lock button:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="1495976579-1">(</span><span class="p" data-group-id="1495976579-2">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="1495976579-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">x</span><span class="p" data-group-id="1495976579-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1495976579-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.666</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="1495976579-3">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="1495976579-4">(</span><span class="ss">a</span><span class="p" data-group-id="1495976579-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="9070980681-5">(</span><span class="ss">b</span><span class="p" data-group-id="9070980681-5">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="1495976579-5">(</span><span class="ss">b</span><span class="p" data-group-id="1495976579-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="9070980681-6">(</span><span class="ss">c</span><span class="p" data-group-id="9070980681-6">)</span><span class="p">.</span><span class="w">
│ │ │ +4&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="1495976579-6">(</span><span class="ss">c</span><span class="p" data-group-id="1495976579-6">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="w">
│ │ │  </span><span class="n">Open</span><span class="gp unselectable">
│ │ │ -5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="9070980681-7">(</span><span class="ss">y</span><span class="p" data-group-id="9070980681-7">)</span><span class="p">.</span><span class="w">
│ │ │ +5&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">button</span><span class="p" data-group-id="1495976579-7">(</span><span class="ss">y</span><span class="p" data-group-id="1495976579-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">set_lock_button</span><span class="p" data-group-id="9070980681-8">(</span><span class="ss">y</span><span class="p" data-group-id="9070980681-8">)</span><span class="p">.</span><span class="w">
│ │ │ +6&gt; </span><span class="nc">code_lock</span><span class="p">:</span><span class="nf">set_lock_button</span><span class="p" data-group-id="1495976579-8">(</span><span class="ss">y</span><span class="p" data-group-id="1495976579-8">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">x</span><span class="w">
│ │ │  </span><span class="c1">% What should happen here?  Immediate lock or nothing?</span></code></pre><p>We could say that the button was pressed too early so it should not be
│ │ │  recognized as the lock button. Or we can make the lock button part of
│ │ │  the state so when we then change the lock button in the locked state,
│ │ │  the change becomes a <em>state change</em> and all postponed events are retried,
│ │ │  therefore the lock is immediately locked!</p><p>We define the state as <code class="inline">{StateName, LockButton}</code>, where <code class="inline">StateName</code>
│ │ │ -is as before and <code class="inline">LockButton</code> is the current lock button:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7143884807-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="7143884807-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="7143884807-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="7143884807-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7143884807-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_3</span><span class="p" data-group-id="7143884807-3">)</span><span class="p">.</span><span class="w">
│ │ │ +is as before and <code class="inline">LockButton</code> is the current lock button:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5230991681-1">(</span><span class="ss">code_lock</span><span class="p" data-group-id="5230991681-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5230991681-2">(</span><span class="ss">gen_statem</span><span class="p" data-group-id="5230991681-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5230991681-3">(</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="ss">code_lock_3</span><span class="p" data-group-id="5230991681-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7143884807-4">(</span><span class="p" data-group-id="7143884807-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="7143884807-5">]</span><span class="p" data-group-id="7143884807-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7143884807-6">(</span><span class="p" data-group-id="7143884807-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">set_lock_button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="7143884807-7">]</span><span class="p" data-group-id="7143884807-6">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7143884807-8">(</span><span class="p" data-group-id="7143884807-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="7143884807-9">]</span><span class="p" data-group-id="7143884807-8">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7143884807-10">(</span><span class="p" data-group-id="7143884807-11">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="7143884807-11">]</span><span class="p" data-group-id="7143884807-10">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="7143884807-12">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">LockButton</span><span class="p" data-group-id="7143884807-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="7143884807-13">(</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7143884807-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="7143884807-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7143884807-15">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="7143884807-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7143884807-16">[</span><span class="p" data-group-id="7143884807-16">]</span><span class="p" data-group-id="7143884807-13">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">stop</span><span class="p" data-group-id="7143884807-17">(</span><span class="p" data-group-id="7143884807-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="7143884807-18">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="7143884807-18">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">button</span><span class="p" data-group-id="7143884807-19">(</span><span class="n">Button</span><span class="p" data-group-id="7143884807-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="7143884807-20">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7143884807-21">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="7143884807-21">}</span><span class="p" data-group-id="7143884807-20">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">set_lock_button</span><span class="p" data-group-id="7143884807-22">(</span><span class="n">LockButton</span><span class="p" data-group-id="7143884807-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="7143884807-23">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7143884807-24">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="7143884807-24">}</span><span class="p" data-group-id="7143884807-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0718549483-1">(</span><span class="p" data-group-id="0718549483-2">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0718549483-2">}</span><span class="p" data-group-id="0718549483-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">process_flag</span><span class="p" data-group-id="0718549483-3">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="0718549483-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0718549483-4">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="0718549483-5">(</span><span class="n">Code</span><span class="p" data-group-id="0718549483-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0718549483-6">[</span><span class="p" data-group-id="0718549483-6">]</span><span class="p" data-group-id="0718549483-4">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0718549483-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0718549483-8">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0718549483-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-7">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5230991681-4">(</span><span class="p" data-group-id="5230991681-5">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">2</span><span class="p">,</span><span class="ss">stop</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5230991681-5">]</span><span class="p" data-group-id="5230991681-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5230991681-6">(</span><span class="p" data-group-id="5230991681-7">[</span><span class="ss">button</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">set_lock_button</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5230991681-7">]</span><span class="p" data-group-id="5230991681-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5230991681-8">(</span><span class="p" data-group-id="5230991681-9">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="ss">callback_mode</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="ss">terminate</span><span class="p">/</span><span class="mi">3</span><span class="p" data-group-id="5230991681-9">]</span><span class="p" data-group-id="5230991681-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5230991681-10">(</span><span class="p" data-group-id="5230991681-11">[</span><span class="ss">handle_event</span><span class="p">/</span><span class="mi">4</span><span class="p" data-group-id="5230991681-11">]</span><span class="p" data-group-id="5230991681-10">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="5230991681-12">(</span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="n">LockButton</span><span class="p" data-group-id="5230991681-12">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5230991681-13">(</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="5230991681-14">{</span><span class="ss">local</span><span class="p">,</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="5230991681-14">}</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230991681-15">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5230991681-15">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230991681-16">[</span><span class="p" data-group-id="5230991681-16">]</span><span class="p" data-group-id="5230991681-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">stop</span><span class="p" data-group-id="5230991681-17">(</span><span class="p" data-group-id="5230991681-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">stop</span><span class="p" data-group-id="5230991681-18">(</span><span class="o">?</span><span class="n">NAME</span><span class="p" data-group-id="5230991681-18">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">button</span><span class="p" data-group-id="5230991681-19">(</span><span class="n">Button</span><span class="p" data-group-id="5230991681-19">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">cast</span><span class="p" data-group-id="5230991681-20">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230991681-21">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="5230991681-21">}</span><span class="p" data-group-id="5230991681-20">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">set_lock_button</span><span class="p" data-group-id="5230991681-22">(</span><span class="n">LockButton</span><span class="p" data-group-id="5230991681-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">gen_statem</span><span class="p">:</span><span class="nf">call</span><span class="p" data-group-id="5230991681-23">(</span><span class="o">?</span><span class="n">NAME</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5230991681-24">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5230991681-24">}</span><span class="p" data-group-id="5230991681-23">)</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="6165531709-1">(</span><span class="p" data-group-id="6165531709-2">{</span><span class="n">Code</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="6165531709-2">}</span><span class="p" data-group-id="6165531709-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">process_flag</span><span class="p" data-group-id="6165531709-3">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="6165531709-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">Data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6165531709-4">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="6165531709-5">(</span><span class="n">Code</span><span class="p" data-group-id="6165531709-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6165531709-6">[</span><span class="p" data-group-id="6165531709-6">]</span><span class="p" data-group-id="6165531709-4">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6165531709-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6165531709-8">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="6165531709-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-7">}</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">callback_mode</span><span class="p" data-group-id="0718549483-9">(</span><span class="p" data-group-id="0718549483-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0718549483-10">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="0718549483-10">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">callback_mode</span><span class="p" data-group-id="6165531709-9">(</span><span class="p" data-group-id="6165531709-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6165531709-10">[</span><span class="ss">handle_event_function</span><span class="p">,</span><span class="ss">state_enter</span><span class="p" data-group-id="6165531709-10">]</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% State: locked</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0718549483-11">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0718549483-12">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0718549483-12">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_lock</span><span class="p" data-group-id="0718549483-13">(</span><span class="p" data-group-id="0718549483-13">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0718549483-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-15">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="0718549483-16">[</span><span class="p" data-group-id="0718549483-16">]</span><span class="p" data-group-id="0718549483-15">}</span><span class="p" data-group-id="0718549483-14">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0718549483-17">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0718549483-18">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0718549483-18">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0718549483-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-20">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="0718549483-21">[</span><span class="p" data-group-id="0718549483-21">]</span><span class="p" data-group-id="0718549483-20">}</span><span class="p" data-group-id="0718549483-19">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0718549483-22">(</span><span class="w">
│ │ │ -  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0718549483-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="0718549483-23">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0718549483-24">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0718549483-24">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="0718549483-25">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="0718549483-25">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="6165531709-11">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6165531709-12">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6165531709-12">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_lock</span><span class="p" data-group-id="6165531709-13">(</span><span class="p" data-group-id="6165531709-13">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6165531709-14">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-15">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6165531709-16">[</span><span class="p" data-group-id="6165531709-16">]</span><span class="p" data-group-id="6165531709-15">}</span><span class="p" data-group-id="6165531709-14">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="6165531709-17">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">button</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6165531709-18">{</span><span class="ss">locked</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="6165531709-18">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-17">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6165531709-19">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-20">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="p" data-group-id="6165531709-21">[</span><span class="p" data-group-id="6165531709-21">]</span><span class="p" data-group-id="6165531709-20">}</span><span class="p" data-group-id="6165531709-19">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="6165531709-22">(</span><span class="w">
│ │ │ +  </span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6165531709-23">{</span><span class="ss">button</span><span class="p">,</span><span class="n">Button</span><span class="p" data-group-id="6165531709-23">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6165531709-24">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="6165531709-24">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="6165531709-25">#{</span><span class="ss">code</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Code</span><span class="p">,</span><span class="w"> </span><span class="nb">length</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Length</span><span class="p">,</span><span class="w"> </span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Buttons</span><span class="p" data-group-id="6165531709-25">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │          </span><span class="k">if</span><span class="w">
│ │ │ -            </span><span class="nf">length</span><span class="p" data-group-id="0718549483-26">(</span><span class="n">Buttons</span><span class="p" data-group-id="0718549483-26">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">length</span><span class="p" data-group-id="6165531709-26">(</span><span class="n">Buttons</span><span class="p" data-group-id="6165531709-26">)</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">Length</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                  </span><span class="n">Buttons</span><span class="p">;</span><span class="w">
│ │ │              </span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                </span><span class="nf">tl</span><span class="p" data-group-id="0718549483-27">(</span><span class="n">Buttons</span><span class="p" data-group-id="0718549483-27">)</span><span class="w">
│ │ │ -        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="0718549483-28">[</span><span class="n">Button</span><span class="p" data-group-id="0718549483-28">]</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="nf">tl</span><span class="p" data-group-id="6165531709-27">(</span><span class="n">Buttons</span><span class="p" data-group-id="6165531709-27">)</span><span class="w">
│ │ │ +        </span><span class="k">end</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="p" data-group-id="6165531709-28">[</span><span class="n">Button</span><span class="p" data-group-id="6165531709-28">]</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">if</span><span class="w">
│ │ │          </span><span class="n">NewButtons</span><span class="w"> </span><span class="o">=:=</span><span class="w"> </span><span class="n">Code</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Correct</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0718549483-29">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0718549483-30">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0718549483-30">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-29">}</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6165531709-29">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6165531709-30">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="6165531709-30">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-29">}</span><span class="p">;</span><span class="w">
│ │ │  	</span><span class="ss">true</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="c1">% Incomplete | Incorrect</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0718549483-31">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0718549483-32">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="0718549483-32">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="0718549483-33">[</span><span class="p" data-group-id="0718549483-34">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="0718549483-34">}</span><span class="p" data-group-id="0718549483-33">]</span><span class="p" data-group-id="0718549483-31">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6165531709-31">{</span><span class="ss">keep_state</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="6165531709-32">#{</span><span class="ss">buttons</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">NewButtons</span><span class="p" data-group-id="6165531709-32">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="6165531709-33">[</span><span class="p" data-group-id="6165531709-34">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">30</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">button</span><span class="p" data-group-id="6165531709-34">}</span><span class="p" data-group-id="6165531709-33">]</span><span class="p" data-group-id="6165531709-31">}</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │  </span><span class="c1">%% State: open</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0326273683-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0326273683-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="0326273683-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="0326273683-3">(</span><span class="p" data-group-id="0326273683-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0326273683-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="0326273683-5">[</span><span class="p" data-group-id="0326273683-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="0326273683-6">}</span><span class="p" data-group-id="0326273683-5">]</span><span class="p" data-group-id="0326273683-4">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0326273683-7">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-8">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0326273683-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0326273683-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0326273683-9">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-10">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0326273683-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0326273683-9">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0326273683-11">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0326273683-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-13">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0326273683-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0326273683-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0326273683-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-15">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="0326273683-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="0326273683-14">}</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="0326273683-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0326273683-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0326273683-18">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="0326273683-18">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="0326273683-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0326273683-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="0326273683-20">[</span><span class="ss">postpone</span><span class="p" data-group-id="0326273683-20">]</span><span class="p" data-group-id="0326273683-19">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5746316801-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5746316801-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="5746316801-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="5746316801-3">(</span><span class="p" data-group-id="5746316801-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5746316801-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="5746316801-5">[</span><span class="p" data-group-id="5746316801-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="5746316801-6">}</span><span class="p" data-group-id="5746316801-5">]</span><span class="p" data-group-id="5746316801-4">}</span><span class="p">;</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5746316801-7">(</span><span class="ss">state_timeout</span><span class="p">,</span><span class="w"> </span><span class="ss">lock</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-8">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5746316801-8">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5746316801-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5746316801-9">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-10">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5746316801-10">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5746316801-9">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5746316801-11">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-12">{</span><span class="ss">button</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5746316801-12">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-13">{</span><span class="ss">open</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5746316801-13">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5746316801-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5746316801-14">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-15">{</span><span class="ss">locked</span><span class="p">,</span><span class="n">LockButton</span><span class="p" data-group-id="5746316801-15">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="5746316801-14">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="5746316801-16">(</span><span class="ss">cast</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-17">{</span><span class="ss">button</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5746316801-17">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5746316801-18">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="5746316801-18">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="5746316801-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5746316801-19">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="p" data-group-id="5746316801-20">[</span><span class="ss">postpone</span><span class="p" data-group-id="5746316801-20">]</span><span class="p" data-group-id="5746316801-19">}</span><span class="p">;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="c1">%%</span><span class="w">
│ │ │  </span><span class="c1">%% Common events</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="7832895222-1">(</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="7832895222-2">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="7832895222-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7832895222-3">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="7832895222-3">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="7832895222-4">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="7832895222-4">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="7832895222-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="7832895222-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7832895222-6">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="7832895222-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="7832895222-7">[</span><span class="p" data-group-id="7832895222-8">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="7832895222-8">}</span><span class="p" data-group-id="7832895222-7">]</span><span class="p" data-group-id="7832895222-5">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="8471178651-1">(</span><span class="p" data-group-id="8471178651-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8471178651-2">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8471178651-3">[</span><span class="p" data-group-id="8471178651-3">]</span><span class="p" data-group-id="8471178651-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">do_unlock</span><span class="p" data-group-id="8471178651-4">(</span><span class="p" data-group-id="8471178651-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8471178651-5">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8471178651-6">[</span><span class="p" data-group-id="8471178651-6">]</span><span class="p" data-group-id="8471178651-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="9759119642-1">(</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="9759119642-2">{</span><span class="ss">call</span><span class="p">,</span><span class="n">From</span><span class="p" data-group-id="9759119642-2">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9759119642-3">{</span><span class="ss">set_lock_button</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="9759119642-3">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="9759119642-4">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="9759119642-4">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9759119642-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9759119642-5">{</span><span class="ss">next_state</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9759119642-6">{</span><span class="n">StateName</span><span class="p">,</span><span class="n">NewLockButton</span><span class="p" data-group-id="9759119642-6">}</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="9759119642-7">[</span><span class="p" data-group-id="9759119642-8">{</span><span class="ss">reply</span><span class="p">,</span><span class="n">From</span><span class="p">,</span><span class="n">OldLockButton</span><span class="p" data-group-id="9759119642-8">}</span><span class="p" data-group-id="9759119642-7">]</span><span class="p" data-group-id="9759119642-5">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">do_lock</span><span class="p" data-group-id="4855235869-1">(</span><span class="p" data-group-id="4855235869-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4855235869-2">(</span><span class="s">&quot;Locked</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4855235869-3">[</span><span class="p" data-group-id="4855235869-3">]</span><span class="p" data-group-id="4855235869-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">do_unlock</span><span class="p" data-group-id="4855235869-4">(</span><span class="p" data-group-id="4855235869-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="4855235869-5">(</span><span class="s">&quot;Open</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4855235869-6">[</span><span class="p" data-group-id="4855235869-6">]</span><span class="p" data-group-id="4855235869-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">terminate</span><span class="p" data-group-id="8471178651-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="8471178651-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="8471178651-8">(</span><span class="p" data-group-id="8471178651-8">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">terminate</span><span class="p" data-group-id="4855235869-7">(</span><span class="p">_</span><span class="n">Reason</span><span class="p">,</span><span class="w"> </span><span class="n">State</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="4855235869-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">State</span><span class="w"> </span><span class="o">=/=</span><span class="w"> </span><span class="ss">locked</span><span class="w"> </span><span class="ow">andalso</span><span class="w"> </span><span class="nf">do_lock</span><span class="p" data-group-id="4855235869-8">(</span><span class="p" data-group-id="4855235869-8">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="ss">ok</span><span class="p">.</span></code></pre><h2 id="hibernation" class="section-heading">
│ │ │    <a href="#hibernation" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Hibernation</span>
│ │ │  </h2>
│ │ │  <p>If you have many servers in one node and they have some state(s) in their
│ │ │ @@ -1428,19 +1428,19 @@
│ │ │  footprint of a server can be minimized by hibernating it through
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/proc_lib.html#hibernate/3"><code class="inline">proc_lib:hibernate/3</code></a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>It is rather costly to hibernate a process; see <a href="../../erts-15.2.7.3/doc/html/erlang.html#hibernate/3"><code class="inline">erlang:hibernate/3</code></a>. It is
│ │ │  not something you want to do after every event.</p></section><p>We can in this example hibernate in the <code class="inline">{open, _}</code> state,
│ │ │  because what normally occurs in that state is that the <em>state time-out</em>
│ │ │  after a while triggers a transition to <code class="inline">{locked, _}</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │  </span><span class="c1">%% State: open</span><span class="w">
│ │ │ -</span><span class="nf">handle_event</span><span class="p" data-group-id="9387315824-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9387315824-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="9387315824-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="9387315824-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">do_unlock</span><span class="p" data-group-id="9387315824-3">(</span><span class="p" data-group-id="9387315824-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9387315824-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ -     </span><span class="p" data-group-id="9387315824-5">[</span><span class="p" data-group-id="9387315824-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="9387315824-6">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ -      </span><span class="ss">hibernate</span><span class="p" data-group-id="9387315824-5">]</span><span class="p" data-group-id="9387315824-4">}</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">handle_event</span><span class="p" data-group-id="4768224491-1">(</span><span class="ss">enter</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">OldState</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4768224491-2">{</span><span class="ss">open</span><span class="p">,</span><span class="p">_</span><span class="p" data-group-id="4768224491-2">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Data</span><span class="p" data-group-id="4768224491-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">do_unlock</span><span class="p" data-group-id="4768224491-3">(</span><span class="p" data-group-id="4768224491-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4768224491-4">{</span><span class="ss">keep_state_and_data</span><span class="p">,</span><span class="w">
│ │ │ +     </span><span class="p" data-group-id="4768224491-5">[</span><span class="p" data-group-id="4768224491-6">{</span><span class="ss">state_timeout</span><span class="p">,</span><span class="mi">10</span><span class="p">_</span><span class="mi">000</span><span class="p">,</span><span class="ss">lock</span><span class="p" data-group-id="4768224491-6">}</span><span class="p">,</span><span class="w"> </span><span class="c1">% Time in milliseconds</span><span class="w">
│ │ │ +      </span><span class="ss">hibernate</span><span class="p" data-group-id="4768224491-5">]</span><span class="p" data-group-id="4768224491-4">}</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span></code></pre><p>The atom <a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#t:hibernate/0"><code class="inline">hibernate</code></a> in the action list on the
│ │ │  last line when entering the <code class="inline">{open, _}</code> state is the only change. If any event
│ │ │  arrives in the <code class="inline">{open, _},</code> state, we do not bother to rehibernate,
│ │ │  so the server stays awake after any event.</p><p>To change that we would need to insert action <code class="inline">hibernate</code> in more places.
│ │ │  For example, the state-independent <code class="inline">set_lock_button</code> operation
│ │ │  would have to use <code class="inline">hibernate</code> but only in the <code class="inline">{open, _}</code> state,
│ │ │  which would clutter the code.</p><p>Another not uncommon scenario is to use the
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/sup_princ.html
│ │ │ @@ -128,48 +128,48 @@
│ │ │  the order specified by this list, and are terminated in the reverse order.</p><h2 id="example" class="section-heading">
│ │ │    <a href="#example" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Example</span>
│ │ │  </h2>
│ │ │  <p>The callback module for a supervisor starting the server from
│ │ │ -<a href="gen_server_concepts.html#ex">gen_server Behaviour</a> can look as follows:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9082469202-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="9082469202-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="9082469202-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="9082469202-2">)</span><span class="p">.</span><span class="w">
│ │ │ +<a href="gen_server_concepts.html#ex">gen_server Behaviour</a> can look as follows:</p><p><a href="" id="ex"></a></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0178452831-1">(</span><span class="ss">ch_sup</span><span class="p" data-group-id="0178452831-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="0178452831-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="0178452831-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9082469202-3">(</span><span class="p" data-group-id="9082469202-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9082469202-4">]</span><span class="p" data-group-id="9082469202-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9082469202-5">(</span><span class="p" data-group-id="9082469202-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="9082469202-6">]</span><span class="p" data-group-id="9082469202-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0178452831-3">(</span><span class="p" data-group-id="0178452831-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0178452831-4">]</span><span class="p" data-group-id="0178452831-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0178452831-5">(</span><span class="p" data-group-id="0178452831-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="0178452831-6">]</span><span class="p" data-group-id="0178452831-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="9082469202-7">(</span><span class="p" data-group-id="9082469202-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="9082469202-8">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9082469202-9">[</span><span class="p" data-group-id="9082469202-9">]</span><span class="p" data-group-id="9082469202-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="0178452831-7">(</span><span class="p" data-group-id="0178452831-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0178452831-8">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0178452831-9">[</span><span class="p" data-group-id="0178452831-9">]</span><span class="p" data-group-id="0178452831-8">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="9082469202-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="9082469202-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9082469202-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_one</span><span class="p">,</span><span class="w"> </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="9082469202-11">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9082469202-12">[</span><span class="p" data-group-id="9082469202-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9082469202-14">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9082469202-15">[</span><span class="p" data-group-id="9082469202-15">]</span><span class="p" data-group-id="9082469202-14">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="0178452831-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="0178452831-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0178452831-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">one_for_one</span><span class="p">,</span><span class="w"> </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">5</span><span class="p" data-group-id="0178452831-11">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0178452831-12">[</span><span class="p" data-group-id="0178452831-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0178452831-14">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0178452831-15">[</span><span class="p" data-group-id="0178452831-15">]</span><span class="p" data-group-id="0178452831-14">}</span><span class="p">,</span><span class="w">
│ │ │                      </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">permanent</span><span class="p">,</span><span class="w">
│ │ │                      </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w">
│ │ │                      </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9082469202-16">[</span><span class="ss">ch3</span><span class="p" data-group-id="9082469202-16">]</span><span class="p" data-group-id="9082469202-13">}</span><span class="p" data-group-id="9082469202-12">]</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9082469202-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9082469202-18">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="9082469202-18">}</span><span class="p" data-group-id="9082469202-17">}</span><span class="p">.</span></code></pre><p>The <code class="inline">SupFlags</code> variable in the return value from <code class="inline">init/1</code> represents the
│ │ │ +                    </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0178452831-16">[</span><span class="ss">ch3</span><span class="p" data-group-id="0178452831-16">]</span><span class="p" data-group-id="0178452831-13">}</span><span class="p" data-group-id="0178452831-12">]</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0178452831-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0178452831-18">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="0178452831-18">}</span><span class="p" data-group-id="0178452831-17">}</span><span class="p">.</span></code></pre><p>The <code class="inline">SupFlags</code> variable in the return value from <code class="inline">init/1</code> represents the
│ │ │  <a href="sup_princ.html#flags">supervisor flags</a>.</p><p>The <code class="inline">ChildSpecs</code> variable in the return value from <code class="inline">init/1</code> is a list of
│ │ │  <a href="sup_princ.html#spec">child specifications</a>.</p><p><a href="" id="flags"></a></p><h2 id="supervisor-flags" class="section-heading">
│ │ │    <a href="#supervisor-flags" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Supervisor Flags</span>
│ │ │  </h2>
│ │ │ -<p>This is the type definition for the supervisor flags:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sup_flags</span><span class="p" data-group-id="4594883881-1">(</span><span class="p" data-group-id="4594883881-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4594883881-2">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">strategy</span><span class="p" data-group-id="4594883881-3">(</span><span class="p" data-group-id="4594883881-3">)</span><span class="p">,</span><span class="w">           </span><span class="c1">% optional</span><span class="w">
│ │ │ -                </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4594883881-4">(</span><span class="p" data-group-id="4594883881-4">)</span><span class="p">,</span><span class="w">   </span><span class="c1">% optional</span><span class="w">
│ │ │ -                </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="4594883881-5">(</span><span class="p" data-group-id="4594883881-5">)</span><span class="p">,</span><span class="w">          </span><span class="c1">% optional</span><span class="w">
│ │ │ -                </span><span class="ss">auto_shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="4594883881-6">(</span><span class="p" data-group-id="4594883881-6">)</span><span class="p" data-group-id="4594883881-2">}</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ -    </span><span class="nf">strategy</span><span class="p" data-group-id="4594883881-7">(</span><span class="p" data-group-id="4594883881-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">one_for_all</span><span class="w">
│ │ │ +<p>This is the type definition for the supervisor flags:</p><pre><code class="makeup erlang" translate="no"><span class="nf">sup_flags</span><span class="p" data-group-id="7017477489-1">(</span><span class="p" data-group-id="7017477489-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7017477489-2">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">strategy</span><span class="p" data-group-id="7017477489-3">(</span><span class="p" data-group-id="7017477489-3">)</span><span class="p">,</span><span class="w">           </span><span class="c1">% optional</span><span class="w">
│ │ │ +                </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="7017477489-4">(</span><span class="p" data-group-id="7017477489-4">)</span><span class="p">,</span><span class="w">   </span><span class="c1">% optional</span><span class="w">
│ │ │ +                </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="7017477489-5">(</span><span class="p" data-group-id="7017477489-5">)</span><span class="p">,</span><span class="w">          </span><span class="c1">% optional</span><span class="w">
│ │ │ +                </span><span class="ss">auto_shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="7017477489-6">(</span><span class="p" data-group-id="7017477489-6">)</span><span class="p" data-group-id="7017477489-2">}</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ +    </span><span class="nf">strategy</span><span class="p" data-group-id="7017477489-7">(</span><span class="p" data-group-id="7017477489-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">one_for_all</span><span class="w">
│ │ │                 </span><span class="p">|</span><span class="w"> </span><span class="ss">one_for_one</span><span class="w">
│ │ │                 </span><span class="p">|</span><span class="w"> </span><span class="ss">rest_for_one</span><span class="w">
│ │ │                 </span><span class="p">|</span><span class="w"> </span><span class="ss">simple_one_for_one</span><span class="w">
│ │ │ -    </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="4594883881-8">(</span><span class="p" data-group-id="4594883881-8">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">never</span><span class="w">
│ │ │ +    </span><span class="nf">auto_shutdown</span><span class="p" data-group-id="7017477489-8">(</span><span class="p" data-group-id="7017477489-8">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">never</span><span class="w">
│ │ │                      </span><span class="p">|</span><span class="w"> </span><span class="ss">any_significant</span><span class="w">
│ │ │                      </span><span class="p">|</span><span class="w"> </span><span class="ss">all_significant</span></code></pre><ul><li><code class="inline">strategy</code> specifies the <a href="sup_princ.html#strategy">restart strategy</a>.</li><li><code class="inline">intensity</code> and <code class="inline">period</code> specify the
│ │ │  <a href="sup_princ.html#max_intensity">maximum restart intensity</a>.</li><li><code class="inline">auto_shutdown</code> specifies whether and when a supervisor should
│ │ │  <a href="sup_princ.html#automatic-shutdown">automatically shut itself down</a>.</li></ul><p><a href="" id="strategy"></a></p><h2 id="restart-strategy" class="section-heading">
│ │ │    <a href="#restart-strategy" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -408,28 +408,28 @@
│ │ │  exhaust the <a href="sup_princ.html#max_intensity">Maximum Restart Intensity</a> of the
│ │ │  parent supervisor.</p></section><p><a href="" id="spec"></a></p><h2 id="child-specification" class="section-heading">
│ │ │    <a href="#child-specification" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Child Specification</span>
│ │ │  </h2>
│ │ │ -<p>The type definition for a child specification is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">child_spec</span><span class="p" data-group-id="3680866104-1">(</span><span class="p" data-group-id="3680866104-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3680866104-2">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">child_id</span><span class="p" data-group-id="3680866104-3">(</span><span class="p" data-group-id="3680866104-3">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% mandatory</span><span class="w">
│ │ │ -                 </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">mfargs</span><span class="p" data-group-id="3680866104-4">(</span><span class="p" data-group-id="3680866104-4">)</span><span class="p">,</span><span class="w">            </span><span class="c1">% mandatory</span><span class="w">
│ │ │ -                 </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">restart</span><span class="p" data-group-id="3680866104-5">(</span><span class="p" data-group-id="3680866104-5">)</span><span class="p">,</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ -                 </span><span class="ss">significant</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">significant</span><span class="p" data-group-id="3680866104-6">(</span><span class="p" data-group-id="3680866104-6">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ -                 </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">shutdown</span><span class="p" data-group-id="3680866104-7">(</span><span class="p" data-group-id="3680866104-7">)</span><span class="p">,</span><span class="w">       </span><span class="c1">% optional</span><span class="w">
│ │ │ -                 </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">worker</span><span class="p" data-group-id="3680866104-8">(</span><span class="p" data-group-id="3680866104-8">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% optional</span><span class="w">
│ │ │ -                 </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">modules</span><span class="p" data-group-id="3680866104-9">(</span><span class="p" data-group-id="3680866104-9">)</span><span class="p" data-group-id="3680866104-2">}</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ -    </span><span class="nf">child_id</span><span class="p" data-group-id="3680866104-10">(</span><span class="p" data-group-id="3680866104-10">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="3680866104-11">(</span><span class="p" data-group-id="3680866104-11">)</span><span class="w">
│ │ │ -    </span><span class="nf">mfargs</span><span class="p" data-group-id="3680866104-12">(</span><span class="p" data-group-id="3680866104-12">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3680866104-13">{</span><span class="n">M</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">module</span><span class="p" data-group-id="3680866104-14">(</span><span class="p" data-group-id="3680866104-14">)</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="3680866104-15">(</span><span class="p" data-group-id="3680866104-15">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="3680866104-16">[</span><span class="nf">term</span><span class="p" data-group-id="3680866104-17">(</span><span class="p" data-group-id="3680866104-17">)</span><span class="p" data-group-id="3680866104-16">]</span><span class="p" data-group-id="3680866104-13">}</span><span class="w">
│ │ │ -    </span><span class="nf">modules</span><span class="p" data-group-id="3680866104-18">(</span><span class="p" data-group-id="3680866104-18">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3680866104-19">[</span><span class="nf">module</span><span class="p" data-group-id="3680866104-20">(</span><span class="p" data-group-id="3680866104-20">)</span><span class="p" data-group-id="3680866104-19">]</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">dynamic</span><span class="w">
│ │ │ -    </span><span class="nf">restart</span><span class="p" data-group-id="3680866104-21">(</span><span class="p" data-group-id="3680866104-21">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">permanent</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">transient</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">temporary</span><span class="w">
│ │ │ -    </span><span class="nf">significant</span><span class="p" data-group-id="3680866104-22">(</span><span class="p" data-group-id="3680866104-22">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="3680866104-23">(</span><span class="p" data-group-id="3680866104-23">)</span><span class="w">
│ │ │ -    </span><span class="nf">shutdown</span><span class="p" data-group-id="3680866104-24">(</span><span class="p" data-group-id="3680866104-24">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">timeout</span><span class="p" data-group-id="3680866104-25">(</span><span class="p" data-group-id="3680866104-25">)</span><span class="w">
│ │ │ -    </span><span class="nf">worker</span><span class="p" data-group-id="3680866104-26">(</span><span class="p" data-group-id="3680866104-26">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">worker</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">supervisor</span></code></pre><ul><li><p><code class="inline">id</code> is used to identify the child specification internally by the supervisor.</p><p>The <code class="inline">id</code> key is mandatory.</p><p>Note that this identifier occasionally has been called &quot;name&quot;. As far as
│ │ │ +<p>The type definition for a child specification is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="nf">child_spec</span><span class="p" data-group-id="2078431005-1">(</span><span class="p" data-group-id="2078431005-1">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2078431005-2">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">child_id</span><span class="p" data-group-id="2078431005-3">(</span><span class="p" data-group-id="2078431005-3">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% mandatory</span><span class="w">
│ │ │ +                 </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">mfargs</span><span class="p" data-group-id="2078431005-4">(</span><span class="p" data-group-id="2078431005-4">)</span><span class="p">,</span><span class="w">            </span><span class="c1">% mandatory</span><span class="w">
│ │ │ +                 </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">restart</span><span class="p" data-group-id="2078431005-5">(</span><span class="p" data-group-id="2078431005-5">)</span><span class="p">,</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ +                 </span><span class="ss">significant</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">significant</span><span class="p" data-group-id="2078431005-6">(</span><span class="p" data-group-id="2078431005-6">)</span><span class="p">,</span><span class="w"> </span><span class="c1">% optional</span><span class="w">
│ │ │ +                 </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">shutdown</span><span class="p" data-group-id="2078431005-7">(</span><span class="p" data-group-id="2078431005-7">)</span><span class="p">,</span><span class="w">       </span><span class="c1">% optional</span><span class="w">
│ │ │ +                 </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">worker</span><span class="p" data-group-id="2078431005-8">(</span><span class="p" data-group-id="2078431005-8">)</span><span class="p">,</span><span class="w">             </span><span class="c1">% optional</span><span class="w">
│ │ │ +                 </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="nf">modules</span><span class="p" data-group-id="2078431005-9">(</span><span class="p" data-group-id="2078431005-9">)</span><span class="p" data-group-id="2078431005-2">}</span><span class="w">         </span><span class="c1">% optional</span><span class="w">
│ │ │ +    </span><span class="nf">child_id</span><span class="p" data-group-id="2078431005-10">(</span><span class="p" data-group-id="2078431005-10">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="2078431005-11">(</span><span class="p" data-group-id="2078431005-11">)</span><span class="w">
│ │ │ +    </span><span class="nf">mfargs</span><span class="p" data-group-id="2078431005-12">(</span><span class="p" data-group-id="2078431005-12">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2078431005-13">{</span><span class="n">M</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">module</span><span class="p" data-group-id="2078431005-14">(</span><span class="p" data-group-id="2078431005-14">)</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="2078431005-15">(</span><span class="p" data-group-id="2078431005-15">)</span><span class="p">,</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="2078431005-16">[</span><span class="nf">term</span><span class="p" data-group-id="2078431005-17">(</span><span class="p" data-group-id="2078431005-17">)</span><span class="p" data-group-id="2078431005-16">]</span><span class="p" data-group-id="2078431005-13">}</span><span class="w">
│ │ │ +    </span><span class="nf">modules</span><span class="p" data-group-id="2078431005-18">(</span><span class="p" data-group-id="2078431005-18">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2078431005-19">[</span><span class="nf">module</span><span class="p" data-group-id="2078431005-20">(</span><span class="p" data-group-id="2078431005-20">)</span><span class="p" data-group-id="2078431005-19">]</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">dynamic</span><span class="w">
│ │ │ +    </span><span class="nf">restart</span><span class="p" data-group-id="2078431005-21">(</span><span class="p" data-group-id="2078431005-21">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">permanent</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">transient</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">temporary</span><span class="w">
│ │ │ +    </span><span class="nf">significant</span><span class="p" data-group-id="2078431005-22">(</span><span class="p" data-group-id="2078431005-22">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="2078431005-23">(</span><span class="p" data-group-id="2078431005-23">)</span><span class="w">
│ │ │ +    </span><span class="nf">shutdown</span><span class="p" data-group-id="2078431005-24">(</span><span class="p" data-group-id="2078431005-24">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">timeout</span><span class="p" data-group-id="2078431005-25">(</span><span class="p" data-group-id="2078431005-25">)</span><span class="w">
│ │ │ +    </span><span class="nf">worker</span><span class="p" data-group-id="2078431005-26">(</span><span class="p" data-group-id="2078431005-26">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">worker</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">supervisor</span></code></pre><ul><li><p><code class="inline">id</code> is used to identify the child specification internally by the supervisor.</p><p>The <code class="inline">id</code> key is mandatory.</p><p>Note that this identifier occasionally has been called &quot;name&quot;. As far as
│ │ │  possible, the terms &quot;identifier&quot; or &quot;id&quot; are now used but in order to keep
│ │ │  backwards compatibility, some occurrences of &quot;name&quot; can still be found, for
│ │ │  example in error messages.</p></li><li><p><code class="inline">start</code> defines the function call used to start the child process. It is a
│ │ │  module-function-arguments tuple used as <a href="../../erts-15.2.7.3/doc/html/erlang.html#apply/3"><code class="inline">apply(M, F, A)</code></a>.</p><p>It is to be (or result in) a call to any of the following:</p><ul><li><a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link/2,3</code></a></li><li><a href="../../lib/stdlib-6.2.2.2/doc/html/gen_server.html#start_link/4"><code class="inline">gen_server:start_link/3,4</code></a></li><li><a href="../../lib/stdlib-6.2.2.2/doc/html/gen_statem.html#start_link/4"><code class="inline">gen_statem:start_link/3,4</code></a></li><li><a href="../../lib/stdlib-6.2.2.2/doc/html/gen_event.html#start_link/2"><code class="inline">gen_event:start_link/0,1,2</code></a></li><li>A function compliant with these functions. For details, see
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html"><code class="inline">supervisor</code></a>.</li></ul><p>The <code class="inline">start</code> key is mandatory.</p></li><li><p><a href="" id="restart"></a> <code class="inline">restart</code> defines when a terminated child process is to be
│ │ │  restarted.</p><ul><li>A <code class="inline">permanent</code> child process is always restarted.</li><li>A <code class="inline">temporary</code> child process is never restarted (not even when the supervisor
│ │ │  restart strategy is <code class="inline">rest_for_one</code> or <code class="inline">one_for_all</code> and a sibling death
│ │ │ @@ -457,53 +457,53 @@
│ │ │  <code class="inline">supervisor</code>, the default value <code class="inline">infinity</code> will be used.</p></li><li><p><code class="inline">type</code> specifies whether the child process is a supervisor or a worker.</p><p>The <code class="inline">type</code> key is optional. If it is not given, the default value <code class="inline">worker</code>
│ │ │  will be used.</p></li><li><p><code class="inline">modules</code> has to be a list consisting of a single element. The value
│ │ │  of that element depends on the behaviour of the process:</p><ul><li>If the child process is a <code class="inline">gen_event</code>, the element has to be the atom
│ │ │  <code class="inline">dynamic</code>.</li><li>Otherwise, the element should be <code class="inline">Module</code>, where <code class="inline">Module</code> is the
│ │ │  name of the callback module.</li></ul><p>This information is used by the release handler during upgrades and
│ │ │  downgrades; see <a href="release_handling.html">Release Handling</a>.</p><p>The <code class="inline">modules</code> key is optional. If it is not given, it defaults to <code class="inline">[M]</code>, where
│ │ │  <code class="inline">M</code> comes from the child's start <code class="inline">{M,F,A}</code>.</p></li></ul><p><em>Example:</em> The child specification to start the server <code class="inline">ch3</code> in the previous
│ │ │ -example look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6329294717-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6329294717-2">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6329294717-3">[</span><span class="p" data-group-id="6329294717-3">]</span><span class="p" data-group-id="6329294717-2">}</span><span class="p">,</span><span class="w">
│ │ │ +example look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9218142706-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9218142706-2">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9218142706-3">[</span><span class="p" data-group-id="9218142706-3">]</span><span class="p" data-group-id="9218142706-2">}</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">permanent</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">worker</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6329294717-4">[</span><span class="ss">ch3</span><span class="p" data-group-id="6329294717-4">]</span><span class="p" data-group-id="6329294717-1">}</span></code></pre><p>or simplified, relying on the default values:</p><pre><code class="text">#{id =&gt; ch3,
│ │ │ +  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="9218142706-4">[</span><span class="ss">ch3</span><span class="p" data-group-id="9218142706-4">]</span><span class="p" data-group-id="9218142706-1">}</span></code></pre><p>or simplified, relying on the default values:</p><pre><code class="text">#{id =&gt; ch3,
│ │ │    start =&gt; {ch3, start_link, []},
│ │ │    shutdown =&gt; brutal_kill}</code></pre><p>Example: A child specification to start the event manager from the chapter about
│ │ │ -<a href="events.html#mgr">gen_event</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7688177195-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">error_man</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7688177195-2">{</span><span class="ss">gen_event</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7688177195-3">[</span><span class="p" data-group-id="7688177195-4">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="7688177195-4">}</span><span class="p" data-group-id="7688177195-3">]</span><span class="p" data-group-id="7688177195-2">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">dynamic</span><span class="p" data-group-id="7688177195-1">}</span></code></pre><p>Both server and event manager are registered processes which can be expected to
│ │ │ +<a href="events.html#mgr">gen_event</a>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1259744959-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">error_man</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1259744959-2">{</span><span class="ss">gen_event</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1259744959-3">[</span><span class="p" data-group-id="1259744959-4">{</span><span class="ss">local</span><span class="p">,</span><span class="w"> </span><span class="ss">error_man</span><span class="p" data-group-id="1259744959-4">}</span><span class="p" data-group-id="1259744959-3">]</span><span class="p" data-group-id="1259744959-2">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="ss">modules</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">dynamic</span><span class="p" data-group-id="1259744959-1">}</span></code></pre><p>Both server and event manager are registered processes which can be expected to
│ │ │  be always accessible. Thus they are specified to be <code class="inline">permanent</code>.</p><p><code class="inline">ch3</code> does not need to do any cleaning up before termination. Thus, no shutdown
│ │ │  time is needed, but <code class="inline">brutal_kill</code> is sufficient. <code class="inline">error_man</code> can need some time
│ │ │  for the event handlers to clean up, thus the shutdown time is set to 5000 ms
│ │ │ -(which is the default value).</p><p>Example: A child specification to start another supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6698256770-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">sup</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="6698256770-2">{</span><span class="ss">sup</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6698256770-3">[</span><span class="p" data-group-id="6698256770-3">]</span><span class="p" data-group-id="6698256770-2">}</span><span class="p">,</span><span class="w">
│ │ │ +(which is the default value).</p><p>Example: A child specification to start another supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3144980409-1">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">sup</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="3144980409-2">{</span><span class="ss">sup</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3144980409-3">[</span><span class="p" data-group-id="3144980409-3">]</span><span class="p" data-group-id="3144980409-2">}</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="ss">restart</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">transient</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="6698256770-1">}</span><span class="w"> </span><span class="c1">% will cause default shutdown=&gt;infinity</span></code></pre><p><a href="" id="super_tree"></a></p><h2 id="starting-a-supervisor" class="section-heading">
│ │ │ +  </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">supervisor</span><span class="p" data-group-id="3144980409-1">}</span><span class="w"> </span><span class="c1">% will cause default shutdown=&gt;infinity</span></code></pre><p><a href="" id="super_tree"></a></p><h2 id="starting-a-supervisor" class="section-heading">
│ │ │    <a href="#starting-a-supervisor" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Starting a Supervisor</span>
│ │ │  </h2>
│ │ │  <p>In the previous example, the supervisor is started by calling
│ │ │ -<code class="inline">ch_sup:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="4444859049-1">(</span><span class="p" data-group-id="4444859049-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="4444859049-2">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4444859049-3">[</span><span class="p" data-group-id="4444859049-3">]</span><span class="p" data-group-id="4444859049-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch_sup:start_link</code> calls function <a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html#start_link/2"><code class="inline">supervisor:start_link/2</code></a>, which spawns and
│ │ │ +<code class="inline">ch_sup:start_link()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">start_link</span><span class="p" data-group-id="0595783501-1">(</span><span class="p" data-group-id="0595783501-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="0595783501-2">(</span><span class="ss">ch_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0595783501-3">[</span><span class="p" data-group-id="0595783501-3">]</span><span class="p" data-group-id="0595783501-2">)</span><span class="p">.</span></code></pre><p><code class="inline">ch_sup:start_link</code> calls function <a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html#start_link/2"><code class="inline">supervisor:start_link/2</code></a>, which spawns and
│ │ │  links to a new process, a supervisor.</p><ul><li>The first argument, <code class="inline">ch_sup</code>, is the name of the callback module, that is, the
│ │ │  module where the <code class="inline">init</code> callback function is located.</li><li>The second argument, <code class="inline">[]</code>, is a term that is passed as is to the callback
│ │ │  function <code class="inline">init</code>. Here, <code class="inline">init</code> does not need any data and ignores the argument.</li></ul><p>In this case, the supervisor is not registered. Instead its pid must be used. A
│ │ │  name can be specified by calling
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link({local, Name}, Module, Args)</code></a>
│ │ │  or
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link({global, Name}, Module, Args)</code></a>.</p><p>The new supervisor process calls the callback function <code class="inline">ch_sup:init([])</code>. <code class="inline">init</code>
│ │ │ -has to return <code class="inline">{ok, {SupFlags, ChildSpecs}}</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="1077297584-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="1077297584-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1077297584-2">#{</span><span class="p" data-group-id="1077297584-2">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1077297584-3">[</span><span class="p" data-group-id="1077297584-4">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="1077297584-5">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1077297584-6">[</span><span class="p" data-group-id="1077297584-6">]</span><span class="p" data-group-id="1077297584-5">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="1077297584-4">}</span><span class="p" data-group-id="1077297584-3">]</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1077297584-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1077297584-8">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="1077297584-8">}</span><span class="p" data-group-id="1077297584-7">}</span><span class="p">.</span></code></pre><p>Subsequently, the supervisor starts its child processes according to the child
│ │ │ +has to return <code class="inline">{ok, {SupFlags, ChildSpecs}}</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">init</span><span class="p" data-group-id="0365395739-1">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="0365395739-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0365395739-2">#{</span><span class="p" data-group-id="0365395739-2">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0365395739-3">[</span><span class="p" data-group-id="0365395739-4">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">ch3</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="0365395739-5">{</span><span class="ss">ch3</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0365395739-6">[</span><span class="p" data-group-id="0365395739-6">]</span><span class="p" data-group-id="0365395739-5">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="0365395739-4">}</span><span class="p" data-group-id="0365395739-3">]</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="0365395739-7">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0365395739-8">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="0365395739-8">}</span><span class="p" data-group-id="0365395739-7">}</span><span class="p">.</span></code></pre><p>Subsequently, the supervisor starts its child processes according to the child
│ │ │  specifications in the start specification. In this case there is a single child
│ │ │  process, called <code class="inline">ch3</code>.</p><p><a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html#start_link/3"><code class="inline">supervisor:start_link/3</code></a> is synchronous. It does not return until all child
│ │ │  processes have been started.</p><h2 id="adding-a-child-process" class="section-heading">
│ │ │    <a href="#adding-a-child-process" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Adding a Child Process</span>
│ │ │ @@ -532,31 +532,31 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Simplified one_for_one Supervisors</span>
│ │ │  </h2>
│ │ │  <p>A supervisor with restart strategy <code class="inline">simple_one_for_one</code> is a simplified
│ │ │  <code class="inline">one_for_one</code> supervisor, where all child processes are dynamically added
│ │ │  instances of the same process.</p><p>The following is an example of a callback module for a <code class="inline">simple_one_for_one</code>
│ │ │ -supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8759385510-1">(</span><span class="ss">simple_sup</span><span class="p" data-group-id="8759385510-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="8759385510-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="8759385510-2">)</span><span class="p">.</span><span class="w">
│ │ │ +supervisor:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5044987476-1">(</span><span class="ss">simple_sup</span><span class="p" data-group-id="5044987476-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">behaviour</span><span class="p" data-group-id="5044987476-2">(</span><span class="ss">supervisor</span><span class="p" data-group-id="5044987476-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8759385510-3">(</span><span class="p" data-group-id="8759385510-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8759385510-4">]</span><span class="p" data-group-id="8759385510-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8759385510-5">(</span><span class="p" data-group-id="8759385510-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="8759385510-6">]</span><span class="p" data-group-id="8759385510-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5044987476-3">(</span><span class="p" data-group-id="5044987476-4">[</span><span class="ss">start_link</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5044987476-4">]</span><span class="p" data-group-id="5044987476-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5044987476-5">(</span><span class="p" data-group-id="5044987476-6">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="5044987476-6">]</span><span class="p" data-group-id="5044987476-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">start_link</span><span class="p" data-group-id="8759385510-7">(</span><span class="p" data-group-id="8759385510-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="8759385510-8">(</span><span class="ss">simple_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8759385510-9">[</span><span class="p" data-group-id="8759385510-9">]</span><span class="p" data-group-id="8759385510-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">start_link</span><span class="p" data-group-id="5044987476-7">(</span><span class="p" data-group-id="5044987476-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">supervisor</span><span class="p">:</span><span class="nf">start_link</span><span class="p" data-group-id="5044987476-8">(</span><span class="ss">simple_sup</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5044987476-9">[</span><span class="p" data-group-id="5044987476-9">]</span><span class="p" data-group-id="5044987476-8">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="8759385510-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="8759385510-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8759385510-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">simple_one_for_one</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="5044987476-10">(</span><span class="p">_</span><span class="n">Args</span><span class="p" data-group-id="5044987476-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">SupFlags</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5044987476-11">#{</span><span class="ss">strategy</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">simple_one_for_one</span><span class="p">,</span><span class="w">
│ │ │                   </span><span class="ss">intensity</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="8759385510-11">}</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8759385510-12">[</span><span class="p" data-group-id="8759385510-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">call</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="8759385510-14">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8759385510-15">[</span><span class="p" data-group-id="8759385510-15">]</span><span class="p" data-group-id="8759385510-14">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="8759385510-13">}</span><span class="p" data-group-id="8759385510-12">]</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8759385510-16">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8759385510-17">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="8759385510-17">}</span><span class="p" data-group-id="8759385510-16">}</span><span class="p">.</span></code></pre><p>When started, the supervisor does not start any child
│ │ │ +                 </span><span class="ss">period</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="5044987476-11">}</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ChildSpecs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5044987476-12">[</span><span class="p" data-group-id="5044987476-13">#{</span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">call</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="ss">start</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="5044987476-14">{</span><span class="ss">call</span><span class="p">,</span><span class="w"> </span><span class="ss">start_link</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5044987476-15">[</span><span class="p" data-group-id="5044987476-15">]</span><span class="p" data-group-id="5044987476-14">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="ss">shutdown</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">brutal_kill</span><span class="p" data-group-id="5044987476-13">}</span><span class="p" data-group-id="5044987476-12">]</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="5044987476-16">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5044987476-17">{</span><span class="n">SupFlags</span><span class="p">,</span><span class="w"> </span><span class="n">ChildSpecs</span><span class="p" data-group-id="5044987476-17">}</span><span class="p" data-group-id="5044987476-16">}</span><span class="p">.</span></code></pre><p>When started, the supervisor does not start any child
│ │ │  processes. Instead, all child processes need to be added dynamically by
│ │ │  calling <a href="../../lib/stdlib-6.2.2.2/doc/html/supervisor.html#start_child/2"><code class="inline">supervisor:start_child(Sup, List)</code></a>.</p><p><code class="inline">Sup</code> is the pid, or name, of the supervisor. <code class="inline">List</code> is an arbitrary list of
│ │ │  terms, which are added to the list of arguments specified in the child
│ │ │  specification. If the start function is specified as <code class="inline">{M, F, A}</code>, the child
│ │ │  process is started by calling <a href="../../erts-15.2.7.3/doc/html/erlang.html#apply/3"><code class="inline">apply(M, F, A++List)</code></a>.</p><p>For example, adding a child to <code class="inline">simple_sup</code> above:</p><pre><code class="text">supervisor:start_child(Pid, [id1])</code></pre><p>The result is that the child process is started by calling
│ │ │  <a href="../../erts-15.2.7.3/doc/html/erlang.html#apply/3"><code class="inline">apply(call, start_link, []++[id1])</code></a>, or actually:</p><pre><code class="text">call:start_link(id1)</code></pre><p>A child under a <code class="inline">simple_one_for_one</code> supervisor can be terminated with the
│ │ │  following:</p><pre><code class="text">supervisor:terminate_child(Sup, Pid)</code></pre><p><code class="inline">Sup</code> is the pid, or name, of the supervisor and <code class="inline">Pid</code> is the pid of the child.</p><p>Because a <code class="inline">simple_one_for_one</code> supervisor can have many children, it shuts them
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/tablesdatabases.html
│ │ │ @@ -146,73 +146,73 @@
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Deleting an Element</span>
│ │ │  </h3>
│ │ │  <p>The <code class="inline">delete</code> operation is considered successful if the element was not present
│ │ │  in the table. Hence all attempts to check that the element is present in the
│ │ │  Ets/Mnesia table before deletion are unnecessary. Here follows an example for
│ │ │ -Ets tables:</p><p><strong>DO</strong></p><pre><code class="text">ets:delete(Tab, Key),</code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="4967893100-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="4967893100-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4967893100-2">[</span><span class="p" data-group-id="4967893100-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +Ets tables:</p><p><strong>DO</strong></p><pre><code class="text">ets:delete(Tab, Key),</code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="6994094473-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="6994094473-1">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6994094473-2">[</span><span class="p" data-group-id="6994094473-2">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4967893100-3">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="4967893100-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">ets</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="4967893100-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="4967893100-4">)</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6994094473-3">[</span><span class="p">_</span><span class="p">|</span><span class="p">_</span><span class="p" data-group-id="6994094473-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nc">ets</span><span class="p">:</span><span class="nf">delete</span><span class="p" data-group-id="6994094473-4">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="6994094473-4">)</span><span class="w">
│ │ │  </span><span class="k">end</span><span class="p">,</span></code></pre><h3 id="fetching-data" class="section-heading">
│ │ │    <a href="#fetching-data" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Fetching Data</span>
│ │ │  </h3>
│ │ │  <p>Do not fetch data that you already have.</p><p>Consider that you have a module that handles the abstract data type <code class="inline">Person</code>.
│ │ │  You export the interface function <code class="inline">print_person/1</code>, which uses the internal
│ │ │  functions <code class="inline">print_name/1</code>, <code class="inline">print_age/1</code>, and <code class="inline">print_occupation/1</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>If the function <code class="inline">print_name/1</code>, and so on, had been interface functions, the
│ │ │  situation would have been different, as you do not want the user of the
│ │ │  interface to know about the internal data representation.</p></section><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Interface function</span><span class="w">
│ │ │ -</span><span class="nf">print_person</span><span class="p" data-group-id="5856701340-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="5856701340-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">print_person</span><span class="p" data-group-id="9191059828-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="9191059828-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Look up the person in the named table person,</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="5856701340-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="5856701340-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5856701340-3">[</span><span class="n">Person</span><span class="p" data-group-id="5856701340-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">print_name</span><span class="p" data-group-id="5856701340-4">(</span><span class="n">Person</span><span class="p" data-group-id="5856701340-4">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">print_age</span><span class="p" data-group-id="5856701340-5">(</span><span class="n">Person</span><span class="p" data-group-id="5856701340-5">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">print_occupation</span><span class="p" data-group-id="5856701340-6">(</span><span class="n">Person</span><span class="p" data-group-id="5856701340-6">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5856701340-7">[</span><span class="p" data-group-id="5856701340-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5856701340-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5856701340-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="5856701340-9">]</span><span class="p" data-group-id="5856701340-8">)</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="9191059828-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="9191059828-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9191059828-3">[</span><span class="n">Person</span><span class="p" data-group-id="9191059828-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">print_name</span><span class="p" data-group-id="9191059828-4">(</span><span class="n">Person</span><span class="p" data-group-id="9191059828-4">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">print_age</span><span class="p" data-group-id="9191059828-5">(</span><span class="n">Person</span><span class="p" data-group-id="9191059828-5">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">print_occupation</span><span class="p" data-group-id="9191059828-6">(</span><span class="n">Person</span><span class="p" data-group-id="9191059828-6">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9191059828-7">[</span><span class="p" data-group-id="9191059828-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9191059828-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9191059828-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="9191059828-9">]</span><span class="p" data-group-id="9191059828-8">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Internal functions</span><span class="w">
│ │ │ -</span><span class="nf">print_name</span><span class="p" data-group-id="5856701340-10">(</span><span class="n">Person</span><span class="p" data-group-id="5856701340-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5856701340-11">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5856701340-12">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="5856701340-12">]</span><span class="p" data-group-id="5856701340-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">print_name</span><span class="p" data-group-id="9191059828-10">(</span><span class="n">Person</span><span class="p" data-group-id="9191059828-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9191059828-11">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9191059828-12">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="9191059828-12">]</span><span class="p" data-group-id="9191059828-11">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">print_age</span><span class="p" data-group-id="5856701340-13">(</span><span class="n">Person</span><span class="p" data-group-id="5856701340-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5856701340-14">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5856701340-15">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="5856701340-15">]</span><span class="p" data-group-id="5856701340-14">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">print_age</span><span class="p" data-group-id="9191059828-13">(</span><span class="n">Person</span><span class="p" data-group-id="9191059828-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9191059828-14">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9191059828-15">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="9191059828-15">]</span><span class="p" data-group-id="9191059828-14">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">print_occupation</span><span class="p" data-group-id="5856701340-16">(</span><span class="n">Person</span><span class="p" data-group-id="5856701340-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5856701340-17">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5856701340-18">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="5856701340-18">]</span><span class="p" data-group-id="5856701340-17">)</span><span class="p">.</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Interface function</span><span class="w">
│ │ │ -</span><span class="nf">print_person</span><span class="p" data-group-id="9217701587-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="9217701587-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">print_occupation</span><span class="p" data-group-id="9191059828-16">(</span><span class="n">Person</span><span class="p" data-group-id="9191059828-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9191059828-17">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9191059828-18">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="9191059828-18">]</span><span class="p" data-group-id="9191059828-17">)</span><span class="p">.</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="c1">%%% Interface function</span><span class="w">
│ │ │ +</span><span class="nf">print_person</span><span class="p" data-group-id="8941087557-1">(</span><span class="n">PersonId</span><span class="p" data-group-id="8941087557-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% Look up the person in the named table person,</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="9217701587-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="9217701587-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="9217701587-3">[</span><span class="n">Person</span><span class="p" data-group-id="9217701587-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">print_name</span><span class="p" data-group-id="9217701587-4">(</span><span class="n">PersonID</span><span class="p" data-group-id="9217701587-4">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">print_age</span><span class="p" data-group-id="9217701587-5">(</span><span class="n">PersonID</span><span class="p" data-group-id="9217701587-5">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">print_occupation</span><span class="p" data-group-id="9217701587-6">(</span><span class="n">PersonID</span><span class="p" data-group-id="9217701587-6">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="9217701587-7">[</span><span class="p" data-group-id="9217701587-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9217701587-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9217701587-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="9217701587-9">]</span><span class="p" data-group-id="9217701587-8">)</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="8941087557-2">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="8941087557-2">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8941087557-3">[</span><span class="n">Person</span><span class="p" data-group-id="8941087557-3">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">print_name</span><span class="p" data-group-id="8941087557-4">(</span><span class="n">PersonID</span><span class="p" data-group-id="8941087557-4">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">print_age</span><span class="p" data-group-id="8941087557-5">(</span><span class="n">PersonID</span><span class="p" data-group-id="8941087557-5">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">print_occupation</span><span class="p" data-group-id="8941087557-6">(</span><span class="n">PersonID</span><span class="p" data-group-id="8941087557-6">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8941087557-7">[</span><span class="p" data-group-id="8941087557-7">]</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8941087557-8">(</span><span class="s">&quot;No person with ID = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8941087557-9">[</span><span class="n">PersonID</span><span class="p" data-group-id="8941087557-9">]</span><span class="p" data-group-id="8941087557-8">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%%% Internal functions</span><span class="w">
│ │ │ -</span><span class="nf">print_name</span><span class="p" data-group-id="9217701587-10">(</span><span class="n">PersonID</span><span class="p" data-group-id="9217701587-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9217701587-11">[</span><span class="n">Person</span><span class="p" data-group-id="9217701587-11">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="9217701587-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="9217701587-12">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9217701587-13">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9217701587-14">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="9217701587-14">]</span><span class="p" data-group-id="9217701587-13">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">print_age</span><span class="p" data-group-id="9217701587-15">(</span><span class="n">PersonID</span><span class="p" data-group-id="9217701587-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9217701587-16">[</span><span class="n">Person</span><span class="p" data-group-id="9217701587-16">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="9217701587-17">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="9217701587-17">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9217701587-18">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9217701587-19">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="9217701587-19">]</span><span class="p" data-group-id="9217701587-18">)</span><span class="p">.</span><span class="w">
│ │ │ -
│ │ │ -</span><span class="nf">print_occupation</span><span class="p" data-group-id="9217701587-20">(</span><span class="n">PersonID</span><span class="p" data-group-id="9217701587-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9217701587-21">[</span><span class="n">Person</span><span class="p" data-group-id="9217701587-21">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="9217701587-22">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="9217701587-22">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="9217701587-23">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9217701587-24">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="9217701587-24">]</span><span class="p" data-group-id="9217701587-23">)</span><span class="p">.</span></code></pre><h3 id="non-persistent-database-storage" class="section-heading">
│ │ │ +</span><span class="nf">print_name</span><span class="p" data-group-id="8941087557-10">(</span><span class="n">PersonID</span><span class="p" data-group-id="8941087557-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8941087557-11">[</span><span class="n">Person</span><span class="p" data-group-id="8941087557-11">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="8941087557-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="8941087557-12">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8941087557-13">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8941087557-14">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="p" data-group-id="8941087557-14">]</span><span class="p" data-group-id="8941087557-13">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">print_age</span><span class="p" data-group-id="8941087557-15">(</span><span class="n">PersonID</span><span class="p" data-group-id="8941087557-15">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8941087557-16">[</span><span class="n">Person</span><span class="p" data-group-id="8941087557-16">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="8941087557-17">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="8941087557-17">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8941087557-18">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8941087557-19">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="8941087557-19">]</span><span class="p" data-group-id="8941087557-18">)</span><span class="p">.</span><span class="w">
│ │ │ +
│ │ │ +</span><span class="nf">print_occupation</span><span class="p" data-group-id="8941087557-20">(</span><span class="n">PersonID</span><span class="p" data-group-id="8941087557-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8941087557-21">[</span><span class="n">Person</span><span class="p" data-group-id="8941087557-21">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="8941087557-22">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="n">PersonId</span><span class="p" data-group-id="8941087557-22">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8941087557-23">(</span><span class="s">&quot;No person </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8941087557-24">[</span><span class="n">Person</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">occupation</span><span class="p" data-group-id="8941087557-24">]</span><span class="p" data-group-id="8941087557-23">)</span><span class="p">.</span></code></pre><h3 id="non-persistent-database-storage" class="section-heading">
│ │ │    <a href="#non-persistent-database-storage" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Non-Persistent Database Storage</span>
│ │ │  </h3>
│ │ │  <p>For non-persistent database storage, prefer Ets tables over Mnesia
│ │ │  <code class="inline">local_content</code> tables. Even the Mnesia <code class="inline">dirty_write</code> operations carry a fixed
│ │ │ @@ -226,38 +226,38 @@
│ │ │  </h3>
│ │ │  <p>Assuming an Ets table that uses <code class="inline">idno</code> as key and contains the following:</p><pre><code class="text">[#person{idno = 1, name = &quot;Adam&quot;,  age = 31, occupation = &quot;mailman&quot;},
│ │ │   #person{idno = 2, name = &quot;Bryan&quot;, age = 31, occupation = &quot;cashier&quot;},
│ │ │   #person{idno = 3, name = &quot;Bryan&quot;, age = 35, occupation = &quot;banker&quot;},
│ │ │   #person{idno = 4, name = &quot;Carl&quot;,  age = 25, occupation = &quot;mailman&quot;}]</code></pre><p>If you <em>must</em> return all data stored in the Ets table, you can use
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#tab2list/1"><code class="inline">ets:tab2list/1</code></a>. However, usually you are only interested in a subset of the
│ │ │  information in which case <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#tab2list/1"><code class="inline">ets:tab2list/1</code></a> is expensive. If you only want to
│ │ │ -extract one field from each record, for example, the age of every person, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="0615766575-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0615766575-2">[</span><span class="p" data-group-id="0615766575-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0615766575-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ +extract one field from each record, for example, the age of every person, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="6719890015-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6719890015-2">[</span><span class="p" data-group-id="6719890015-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="6719890015-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │                            </span><span class="ss">name</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │                            </span><span class="ss">age</span><span class="o">=</span><span class="ss">&#39;$1&#39;</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="0615766575-4">}</span><span class="p">,</span><span class="w">
│ │ │ -                </span><span class="p" data-group-id="0615766575-5">[</span><span class="p" data-group-id="0615766575-5">]</span><span class="p">,</span><span class="w">
│ │ │ -                </span><span class="p" data-group-id="0615766575-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="0615766575-6">]</span><span class="p" data-group-id="0615766575-3">}</span><span class="p" data-group-id="0615766575-2">]</span><span class="p" data-group-id="0615766575-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="6341071532-1">(</span><span class="n">Tab</span><span class="p" data-group-id="6341071532-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="6341071532-2">(</span><span class="nf">fun</span><span class="p" data-group-id="6341071532-3">(</span><span class="n">X</span><span class="p" data-group-id="6341071532-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="6341071532-2">)</span><span class="p">,</span></code></pre><p>If you are only interested in the age of all persons named &quot;Bryan&quot;, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="4999815587-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4999815587-2">[</span><span class="p" data-group-id="4999815587-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4999815587-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ +                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="6719890015-4">}</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="p" data-group-id="6719890015-5">[</span><span class="p" data-group-id="6719890015-5">]</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="p" data-group-id="6719890015-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="6719890015-6">]</span><span class="p" data-group-id="6719890015-3">}</span><span class="p" data-group-id="6719890015-2">]</span><span class="p" data-group-id="6719890015-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="2683517086-1">(</span><span class="n">Tab</span><span class="p" data-group-id="2683517086-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="2683517086-2">(</span><span class="nf">fun</span><span class="p" data-group-id="2683517086-3">(</span><span class="n">X</span><span class="p" data-group-id="2683517086-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="2683517086-2">)</span><span class="p">,</span></code></pre><p>If you are only interested in the age of all persons named &quot;Bryan&quot;, then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="2095523972-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2095523972-2">[</span><span class="p" data-group-id="2095523972-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2095523972-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │                            </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Bryan&quot;</span><span class="p">,</span><span class="w">
│ │ │                            </span><span class="ss">age</span><span class="o">=</span><span class="ss">&#39;$1&#39;</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="4999815587-4">}</span><span class="p">,</span><span class="w">
│ │ │ -                </span><span class="p" data-group-id="4999815587-5">[</span><span class="p" data-group-id="4999815587-5">]</span><span class="p">,</span><span class="w">
│ │ │ -                </span><span class="p" data-group-id="4999815587-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="4999815587-6">]</span><span class="p" data-group-id="4999815587-3">}</span><span class="p" data-group-id="4999815587-2">]</span><span class="p" data-group-id="4999815587-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="1580232038-1">(</span><span class="n">Tab</span><span class="p" data-group-id="1580232038-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="1580232038-2">(</span><span class="nf">fun</span><span class="p" data-group-id="1580232038-3">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="1580232038-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="2095523972-4">}</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="p" data-group-id="2095523972-5">[</span><span class="p" data-group-id="2095523972-5">]</span><span class="p">,</span><span class="w">
│ │ │ +                </span><span class="p" data-group-id="2095523972-6">[</span><span class="ss">&#39;$1&#39;</span><span class="p" data-group-id="2095523972-6">]</span><span class="p" data-group-id="2095523972-3">}</span><span class="p" data-group-id="2095523972-2">]</span><span class="p" data-group-id="2095523972-1">)</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="7599999218-1">(</span><span class="n">Tab</span><span class="p" data-group-id="7599999218-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="7599999218-2">(</span><span class="nf">fun</span><span class="p" data-group-id="7599999218-3">(</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7599999218-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │                                  </span><span class="s">&quot;Bryan&quot;</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                                    </span><span class="p" data-group-id="1580232038-4">[</span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="1580232038-4">]</span><span class="p">;</span><span class="w">
│ │ │ +                                    </span><span class="p" data-group-id="7599999218-4">[</span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p">|</span><span class="n">Acc</span><span class="p" data-group-id="7599999218-4">]</span><span class="p">;</span><span class="w">
│ │ │                                   </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                                       </span><span class="n">Acc</span><span class="w">
│ │ │                             </span><span class="k">end</span><span class="w">
│ │ │ -             </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1580232038-5">[</span><span class="p" data-group-id="1580232038-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="1580232038-2">)</span></code></pre><p>If you need all information stored in the Ets table about persons named &quot;Bryan&quot;,
│ │ │ -then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="2114780279-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2114780279-2">[</span><span class="p" data-group-id="2114780279-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2114780279-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7599999218-5">[</span><span class="p" data-group-id="7599999218-5">]</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="7599999218-2">)</span></code></pre><p>If you need all information stored in the Ets table about persons named &quot;Bryan&quot;,
│ │ │ +then:</p><p><strong>DO</strong></p><pre><code class="makeup erlang" translate="no"><span class="nc">ets</span><span class="p">:</span><span class="nf">select</span><span class="p" data-group-id="2094687076-1">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2094687076-2">[</span><span class="p" data-group-id="2094687076-3">{</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="2094687076-4">{</span><span class="ss">idno</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │                            </span><span class="ss">name</span><span class="o">=</span><span class="s">&quot;Bryan&quot;</span><span class="p">,</span><span class="w">
│ │ │                            </span><span class="ss">age</span><span class="o">=</span><span class="ss">&#39;_&#39;</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="2114780279-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2114780279-5">[</span><span class="p" data-group-id="2114780279-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2114780279-6">[</span><span class="ss">&#39;$_&#39;</span><span class="p" data-group-id="2114780279-6">]</span><span class="p" data-group-id="2114780279-3">}</span><span class="p" data-group-id="2114780279-2">]</span><span class="p" data-group-id="2114780279-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="9964268208-1">(</span><span class="n">Tab</span><span class="p" data-group-id="9964268208-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="9964268208-2">(</span><span class="nf">fun</span><span class="p" data-group-id="9964268208-3">(</span><span class="n">X</span><span class="p" data-group-id="9964268208-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="s">&quot;Bryan&quot;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="9964268208-2">)</span><span class="p">,</span></code></pre><h3 id="ordered_set-tables" class="section-heading">
│ │ │ +                          </span><span class="ss">occupation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="2094687076-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2094687076-5">[</span><span class="p" data-group-id="2094687076-5">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2094687076-6">[</span><span class="ss">&#39;$_&#39;</span><span class="p" data-group-id="2094687076-6">]</span><span class="p" data-group-id="2094687076-3">}</span><span class="p" data-group-id="2094687076-2">]</span><span class="p" data-group-id="2094687076-1">)</span><span class="p">,</span></code></pre><p><strong>DO NOT</strong></p><pre><code class="makeup erlang" translate="no"><span class="n">TabList</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">tab2list</span><span class="p" data-group-id="5586028231-1">(</span><span class="n">Tab</span><span class="p" data-group-id="5586028231-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">filter</span><span class="p" data-group-id="5586028231-2">(</span><span class="nf">fun</span><span class="p" data-group-id="5586028231-3">(</span><span class="n">X</span><span class="p" data-group-id="5586028231-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">name</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="s">&quot;Bryan&quot;</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">TabList</span><span class="p" data-group-id="5586028231-2">)</span><span class="p">,</span></code></pre><h3 id="ordered_set-tables" class="section-heading">
│ │ │    <a href="#ordered_set-tables" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text"><code class="inline">ordered_set</code> Tables</span>
│ │ │  </h3>
│ │ │  <p>If the data in the table is to be accessed so that the order of the keys in the
│ │ │  table is significant, the table type <code class="inline">ordered_set</code> can be used instead of the
│ │ │ @@ -293,20 +293,20 @@
│ │ │  Clearly, the second table would have to be kept consistent with the master
│ │ │  table. Mnesia can do this for you, but a home-brew index table can be very
│ │ │  efficient compared to the overhead involved in using Mnesia.</p><p>An index table for the table in the previous examples would have to be a bag (as
│ │ │  keys would appear more than once) and can have the following contents:</p><pre><code class="text">[#index_entry{name=&quot;Adam&quot;, idno=1},
│ │ │   #index_entry{name=&quot;Bryan&quot;, idno=2},
│ │ │   #index_entry{name=&quot;Bryan&quot;, idno=3},
│ │ │   #index_entry{name=&quot;Carl&quot;, idno=4}]</code></pre><p>Given this index table, a lookup of the <code class="inline">age</code> fields for all persons named
│ │ │ -&quot;Bryan&quot; can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">MatchingIDs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3918462720-1">(</span><span class="n">IndexTable</span><span class="p">,</span><span class="s">&quot;Bryan&quot;</span><span class="p" data-group-id="3918462720-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="3918462720-2">(</span><span class="nf">fun</span><span class="p" data-group-id="3918462720-3">(</span><span class="o">#</span><span class="ss">index_entry</span><span class="p" data-group-id="3918462720-4">{</span><span class="ss">idno</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="3918462720-4">}</span><span class="p" data-group-id="3918462720-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="3918462720-5">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="3918462720-6">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="3918462720-6">}</span><span class="p" data-group-id="3918462720-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="3918462720-7">(</span><span class="n">PersonTable</span><span class="p">,</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="3918462720-7">)</span><span class="p">,</span><span class="w">
│ │ │ +&quot;Bryan&quot; can be done as follows:</p><pre><code class="makeup erlang" translate="no"><span class="n">MatchingIDs</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="4996797984-1">(</span><span class="n">IndexTable</span><span class="p">,</span><span class="s">&quot;Bryan&quot;</span><span class="p" data-group-id="4996797984-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="4996797984-2">(</span><span class="nf">fun</span><span class="p" data-group-id="4996797984-3">(</span><span class="o">#</span><span class="ss">index_entry</span><span class="p" data-group-id="4996797984-4">{</span><span class="ss">idno</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="4996797984-4">}</span><span class="p" data-group-id="4996797984-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="4996797984-5">[</span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="4996797984-6">{</span><span class="ss">age</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Age</span><span class="p" data-group-id="4996797984-6">}</span><span class="p" data-group-id="4996797984-5">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">ets</span><span class="p">:</span><span class="nf">lookup</span><span class="p" data-group-id="4996797984-7">(</span><span class="n">PersonTable</span><span class="p">,</span><span class="w"> </span><span class="n">ID</span><span class="p" data-group-id="4996797984-7">)</span><span class="p">,</span><span class="w">
│ │ │                   </span><span class="n">Age</span><span class="w">
│ │ │            </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="n">MatchingIDs</span><span class="p" data-group-id="3918462720-2">)</span><span class="p">,</span></code></pre><p>Notice that this code does not use <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a>, but instead uses the
│ │ │ +          </span><span class="n">MatchingIDs</span><span class="p" data-group-id="4996797984-2">)</span><span class="p">,</span></code></pre><p>Notice that this code does not use <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#match/2"><code class="inline">ets:match/2</code></a>, but instead uses the
│ │ │  <a href="../../lib/stdlib-6.2.2.2/doc/html/ets.html#lookup/2"><code class="inline">ets:lookup/2</code></a> call. The <a href="../../lib/stdlib-6.2.2.2/doc/html/lists.html#map/2"><code class="inline">lists:map/2</code></a> call is only used to traverse the <code class="inline">idno</code>s
│ │ │  matching the name &quot;Bryan&quot; in the table; thus the number of lookups in the master
│ │ │  table is minimized.</p><p>Keeping an index table introduces some overhead when inserting records in the
│ │ │  table. The number of operations gained from the table must therefore be compared
│ │ │  against the number of operations inserting objects in the table. However, notice
│ │ │  that the gain is significant when the key can be used to lookup elements.</p><h2 id="mnesia" class="section-heading">
│ │ │    <a href="#mnesia" class="hover-link">
│ │ │ @@ -321,51 +321,51 @@
│ │ │    <span class="text">Secondary Index</span>
│ │ │  </h3>
│ │ │  <p>If you frequently do lookups on a field that is not the key of the table, you
│ │ │  lose performance using <a href="../../lib/mnesia-4.23.5/doc/html/mnesia.html#select/3">mnesia:select()</a> or
│ │ │  <a href="../../lib/mnesia-4.23.5/doc/html/mnesia.html#match_object/1"><code class="inline">mnesia:match_object()</code></a> as these function traverse
│ │ │  the whole table. Instead, you can create a secondary index and use
│ │ │  <a href="../../lib/mnesia-4.23.5/doc/html/mnesia.html#index_read/3"><code class="inline">mnesia:index_read/3</code></a> to get faster access at the expense of using more
│ │ │ -memory.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5995135183-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5995135183-2">{</span><span class="ss">idno</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">occupation</span><span class="p" data-group-id="5995135183-2">}</span><span class="p" data-group-id="5995135183-1">)</span><span class="p">.</span><span class="w">
│ │ │ +memory.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1880425433-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1880425433-2">{</span><span class="ss">idno</span><span class="p">,</span><span class="w"> </span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p">,</span><span class="w"> </span><span class="ss">occupation</span><span class="p" data-group-id="1880425433-2">}</span><span class="p" data-group-id="1880425433-1">)</span><span class="p">.</span><span class="w">
│ │ │          </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5995135183-3">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="5995135183-3">}</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ -</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">create_table</span><span class="p" data-group-id="5995135183-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5995135183-5">[</span><span class="p" data-group-id="5995135183-6">{</span><span class="ss">index</span><span class="p">,</span><span class="p" data-group-id="5995135183-7">[</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="5995135183-7">]</span><span class="p" data-group-id="5995135183-6">}</span><span class="p">,</span><span class="w">
│ │ │ -                              </span><span class="p" data-group-id="5995135183-8">{</span><span class="ss">attributes</span><span class="p">,</span><span class="w">
│ │ │ -                                    </span><span class="nf">record_info</span><span class="p" data-group-id="5995135183-9">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="5995135183-9">)</span><span class="p" data-group-id="5995135183-8">}</span><span class="p" data-group-id="5995135183-5">]</span><span class="p" data-group-id="5995135183-4">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5995135183-10">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="5995135183-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">add_table_index</span><span class="p" data-group-id="5995135183-11">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="5995135183-11">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1880425433-3">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="1880425433-3">}</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ +</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">create_table</span><span class="p" data-group-id="1880425433-4">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1880425433-5">[</span><span class="p" data-group-id="1880425433-6">{</span><span class="ss">index</span><span class="p">,</span><span class="p" data-group-id="1880425433-7">[</span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="1880425433-7">]</span><span class="p" data-group-id="1880425433-6">}</span><span class="p">,</span><span class="w">
│ │ │ +                              </span><span class="p" data-group-id="1880425433-8">{</span><span class="ss">attributes</span><span class="p">,</span><span class="w">
│ │ │ +                                    </span><span class="nf">record_info</span><span class="p" data-group-id="1880425433-9">(</span><span class="ss">fields</span><span class="p">,</span><span class="w"> </span><span class="ss">person</span><span class="p" data-group-id="1880425433-9">)</span><span class="p" data-group-id="1880425433-8">}</span><span class="p" data-group-id="1880425433-5">]</span><span class="p" data-group-id="1880425433-4">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1880425433-10">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p" data-group-id="1880425433-10">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">add_table_index</span><span class="p" data-group-id="1880425433-11">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="ss">age</span><span class="p" data-group-id="1880425433-11">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="n">PersonsAge42</span><span class="w"> </span><span class="o">=</span><span class="w">
│ │ │ -     </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_index_read</span><span class="p" data-group-id="5995135183-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="5995135183-12">)</span><span class="p">,</span></code></pre><h3 id="transactions" class="section-heading">
│ │ │ +     </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_index_read</span><span class="p" data-group-id="1880425433-12">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p">.</span><span class="ss">age</span><span class="p" data-group-id="1880425433-12">)</span><span class="p">,</span></code></pre><h3 id="transactions" class="section-heading">
│ │ │    <a href="#transactions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Transactions</span>
│ │ │  </h3>
│ │ │  <p>Using transactions is a way to guarantee that the distributed Mnesia database
│ │ │  remains consistent, even when many different processes update it in parallel.
│ │ │  However, if you have real-time requirements it is recommended to use dirtry
│ │ │  operations instead of transactions. When using dirty operations, you lose the
│ │ │  consistency guarantee; this is usually solved by only letting one process update
│ │ │  the table. Other processes must send update requests to that process.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="c1">%% Using transaction</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1563439163-1">(</span><span class="p" data-group-id="1563439163-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="1563439163-2">[</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="1563439163-3">(</span><span class="p" data-group-id="1563439163-4">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="1563439163-4">}</span><span class="p" data-group-id="1563439163-3">)</span><span class="p">,</span><span class="w">
│ │ │ -           </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="1563439163-5">(</span><span class="p" data-group-id="1563439163-6">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="1563439163-6">}</span><span class="p" data-group-id="1563439163-5">)</span><span class="p" data-group-id="1563439163-2">]</span><span class="w">
│ │ │ +</span><span class="n">Fun</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="3064746236-1">(</span><span class="p" data-group-id="3064746236-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="3064746236-2">[</span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="3064746236-3">(</span><span class="p" data-group-id="3064746236-4">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="3064746236-4">}</span><span class="p" data-group-id="3064746236-3">)</span><span class="p">,</span><span class="w">
│ │ │ +           </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">read</span><span class="p" data-group-id="3064746236-5">(</span><span class="p" data-group-id="3064746236-6">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="3064746236-6">}</span><span class="p" data-group-id="3064746236-5">)</span><span class="p" data-group-id="3064746236-2">]</span><span class="w">
│ │ │        </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │  
│ │ │ -</span><span class="p" data-group-id="1563439163-7">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1563439163-8">[</span><span class="n">Result1</span><span class="p">,</span><span class="w"> </span><span class="n">Result2</span><span class="p" data-group-id="1563439163-8">]</span><span class="p" data-group-id="1563439163-7">}</span><span class="w">  </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">transaction</span><span class="p" data-group-id="1563439163-9">(</span><span class="n">Fun</span><span class="p" data-group-id="1563439163-9">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3064746236-7">{</span><span class="ss">atomic</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3064746236-8">[</span><span class="n">Result1</span><span class="p">,</span><span class="w"> </span><span class="n">Result2</span><span class="p" data-group-id="3064746236-8">]</span><span class="p" data-group-id="3064746236-7">}</span><span class="w">  </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">transaction</span><span class="p" data-group-id="3064746236-9">(</span><span class="n">Fun</span><span class="p" data-group-id="3064746236-9">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │  </span><span class="c1">%% Same thing using dirty operations</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Result1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="1563439163-10">(</span><span class="p" data-group-id="1563439163-11">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="1563439163-11">}</span><span class="p" data-group-id="1563439163-10">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Result2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="1563439163-12">(</span><span class="p" data-group-id="1563439163-13">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="1563439163-13">}</span><span class="p" data-group-id="1563439163-12">)</span><span class="p">,</span></code></pre>
│ │ │ +</span><span class="n">Result1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="3064746236-10">(</span><span class="p" data-group-id="3064746236-11">{</span><span class="n">Table</span><span class="p">,</span><span class="w"> </span><span class="n">Key</span><span class="p" data-group-id="3064746236-11">}</span><span class="p" data-group-id="3064746236-10">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Result2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">mnesia</span><span class="p">:</span><span class="nf">dirty_read</span><span class="p" data-group-id="3064746236-12">(</span><span class="p" data-group-id="3064746236-13">{</span><span class="n">Table2</span><span class="p">,</span><span class="w"> </span><span class="n">Key2</span><span class="p" data-group-id="3064746236-13">}</span><span class="p" data-group-id="3064746236-12">)</span><span class="p">,</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="eff_guide_functions.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/system/typespec.html
│ │ │ @@ -238,124 +238,124 @@
│ │ │  and optional <code class="inline">(=&gt;)</code> association types. If an association type is mandatory, an
│ │ │  association with that type needs to be present. In the case of an optional
│ │ │  association type it is not required for the key type to be present.</p><p>The notation <code class="inline">#{}</code> specifies the singleton type for the empty map. Note that
│ │ │  this notation is not a shorthand for the <a href="../../erts-15.2.7.3/doc/html/erlang.html#t:map/0"><code class="inline">map/0</code></a> type.</p><p>For convenience, the following types are also built-in. They can be thought as
│ │ │  predefined aliases for the type unions also shown in the table.</p><p><a href="" id="builtin_types"></a></p><table><thead><tr><th style="text-align: left;"><em>Built-in type</em></th><th style="text-align: left;"><em>Defined as</em></th></tr></thead><tbody><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:term/0"><code class="inline">term/0</code></a></td><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:any/0"><code class="inline">any/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:binary/0"><code class="inline">binary/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:_*8&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:nonempty_binary/0"><code class="inline">nonempty_binary/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:8, _:_*8&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:bitstring/0"><code class="inline">bitstring/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:_*1&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:nonempty_bitstring/0"><code class="inline">nonempty_bitstring/0</code></a></td><td style="text-align: left;"><code class="inline">&lt;&lt;_:1, _:_*1&gt;&gt;</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:boolean/0"><code class="inline">boolean/0</code></a></td><td style="text-align: left;"><code class="inline">'false'</code> | <code class="inline">'true'</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:byte/0"><code class="inline">byte/0</code></a></td><td style="text-align: left;"><code class="inline">0..255</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:char/0"><code class="inline">char/0</code></a></td><td style="text-align: left;"><code class="inline">0..16#10ffff</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:nil/0"><code class="inline">nil/0</code></a></td><td style="text-align: left;"><code class="inline">[]</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:number/0"><code class="inline">number/0</code></a></td><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:integer/0"><code class="inline">integer/0</code></a> | <a href="../../erts-15.2.7.3/doc/html/erlang.html#t:float/0"><code class="inline">float/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:list/0"><code class="inline">list/0</code></a></td><td style="text-align: left;"><code class="inline">[any()]</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:maybe_improper_list/0"><code class="inline">maybe_improper_list/0</code></a></td><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:maybe_improper_list/2"><code class="inline">maybe_improper_list(any(), any())</code></a></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:nonempty_list/0"><code class="inline">nonempty_list/0</code></a></td><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:nonempty_list/1"><code class="inline">nonempty_list(any())</code></a></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:string/0"><code class="inline">string/0</code></a></td><td style="text-align: left;"><code class="inline">[char()]</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:nonempty_string/0"><code class="inline">nonempty_string/0</code></a></td><td style="text-align: left;"><code class="inline">[char(),...]</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:iodata/0"><code class="inline">iodata/0</code></a></td><td style="text-align: left;"><code class="inline">iolist()</code> | <code class="inline">binary()</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:iolist/0"><code class="inline">iolist/0</code></a></td><td style="text-align: left;"><code class="inline">maybe_improper_list(byte()</code> | <code class="inline">binary()</code> | <code class="inline">iolist(), binary()</code> | <code class="inline">[])</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:map/0"><code class="inline">map/0</code></a></td><td style="text-align: left;"><code class="inline">#{any() =&gt; any()}</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:function/0"><code class="inline">function/0</code></a></td><td style="text-align: left;"><code class="inline">fun()</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:module/0"><code class="inline">module/0</code></a></td><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:atom/0"><code class="inline">atom/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:mfa/0"><code class="inline">mfa/0</code></a></td><td style="text-align: left;"><code class="inline">{module(),atom(),arity()}</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:arity/0"><code class="inline">arity/0</code></a></td><td style="text-align: left;"><code class="inline">0..255</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:identifier/0"><code class="inline">identifier/0</code></a></td><td style="text-align: left;"><code class="inline">pid()</code> | <code class="inline">port()</code> | <code class="inline">reference()</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#node/0"><code class="inline">node/0</code></a></td><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:atom/0"><code class="inline">atom/0</code></a></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:timeout/0"><code class="inline">timeout/0</code></a></td><td style="text-align: left;"><code class="inline">'infinity'</code> | <code class="inline">non_neg_integer()</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:no_return/0"><code class="inline">no_return/0</code></a></td><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:none/0"><code class="inline">none/0</code></a></td></tr></tbody></table><p><em>Table: Built-in types, predefined aliases</em></p><p>In addition, the following three built-in types exist and can be thought as
│ │ │  defined below, though strictly their &quot;type definition&quot; is not valid syntax
│ │ │  according to the type language defined above.</p><table><thead><tr><th style="text-align: left;"><em>Built-in type</em></th><th style="text-align: left;"><em>Can be thought defined by the syntax</em></th></tr></thead><tbody><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:non_neg_integer/0"><code class="inline">non_neg_integer/0</code></a></td><td style="text-align: left;"><code class="inline">0..</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:pos_integer/0"><code class="inline">pos_integer/0</code></a></td><td style="text-align: left;"><code class="inline">1..</code></td></tr><tr><td style="text-align: left;"><a href="../../erts-15.2.7.3/doc/html/erlang.html#t:neg_integer/0"><code class="inline">neg_integer/0</code></a></td><td style="text-align: left;"><code class="inline">..-1</code></td></tr></tbody></table><p><em>Table: Additional built-in types</em></p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The following built-in list types also exist, but they are expected to be
│ │ │ -rarely used. Hence, they have long names:</p></section><pre><code class="makeup erlang" translate="no"><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="3390933493-1">(</span><span class="p" data-group-id="3390933493-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="3390933493-2">(</span><span class="nf">any</span><span class="p" data-group-id="3390933493-3">(</span><span class="p" data-group-id="3390933493-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="3390933493-4">(</span><span class="p" data-group-id="3390933493-4">)</span><span class="p" data-group-id="3390933493-2">)</span><span class="w">
│ │ │ -</span><span class="nf">nonempty_improper_list</span><span class="p" data-group-id="3390933493-5">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="3390933493-5">)</span><span class="w">
│ │ │ -</span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="3390933493-6">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="3390933493-6">)</span></code></pre><p>where the last two types define the set of Erlang terms one would expect.</p><p>Also for convenience, record notation is allowed to be used. Records are
│ │ │ -shorthands for the corresponding tuples:</p><pre><code class="makeup erlang" translate="no"><span class="n">Record</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="9057334160-1">{</span><span class="p" data-group-id="9057334160-1">}</span><span class="w">
│ │ │ -        </span><span class="p">|</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="9057334160-2">{</span><span class="n">Fields</span><span class="p" data-group-id="9057334160-2">}</span></code></pre><p>Records are extended to possibly contain type information. This is described in
│ │ │ +rarely used. Hence, they have long names:</p></section><pre><code class="makeup erlang" translate="no"><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="2297661928-1">(</span><span class="p" data-group-id="2297661928-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="2297661928-2">(</span><span class="nf">any</span><span class="p" data-group-id="2297661928-3">(</span><span class="p" data-group-id="2297661928-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="2297661928-4">(</span><span class="p" data-group-id="2297661928-4">)</span><span class="p" data-group-id="2297661928-2">)</span><span class="w">
│ │ │ +</span><span class="nf">nonempty_improper_list</span><span class="p" data-group-id="2297661928-5">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="2297661928-5">)</span><span class="w">
│ │ │ +</span><span class="nf">nonempty_maybe_improper_list</span><span class="p" data-group-id="2297661928-6">(</span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="n">Type2</span><span class="p" data-group-id="2297661928-6">)</span></code></pre><p>where the last two types define the set of Erlang terms one would expect.</p><p>Also for convenience, record notation is allowed to be used. Records are
│ │ │ +shorthands for the corresponding tuples:</p><pre><code class="makeup erlang" translate="no"><span class="n">Record</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="9008505203-1">{</span><span class="p" data-group-id="9008505203-1">}</span><span class="w">
│ │ │ +        </span><span class="p">|</span><span class="w"> </span><span class="p">#</span><span class="n">Erlang_Atom</span><span class="p" data-group-id="9008505203-2">{</span><span class="n">Fields</span><span class="p" data-group-id="9008505203-2">}</span></code></pre><p>Records are extended to possibly contain type information. This is described in
│ │ │  <a href="typespec.html#typeinrecords">Type Information in Record Declarations</a>.</p><h3 id="redefining-built-in-types" class="section-heading">
│ │ │    <a href="#redefining-built-in-types" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Redefining built-in types</span>
│ │ │  </h3>
│ │ │  <section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Starting from Erlang/OTP 26, it is permitted to define a type having the same
│ │ │  name as a built-in type.</p></section><p>It is recommended to avoid deliberately reusing built-in names because it can be
│ │ │  confusing. However, when an Erlang/OTP release introduces a new type, code that
│ │ │  happened to define its own type having the same name will continue to work.</p><p>As an example, imagine that the Erlang/OTP 42 release introduces a new type
│ │ │ -<code class="inline">gadget()</code> defined like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="2076950878-1">(</span><span class="p" data-group-id="2076950878-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="2076950878-2">{</span><span class="ss">&#39;gadget&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">reference</span><span class="p" data-group-id="2076950878-3">(</span><span class="p" data-group-id="2076950878-3">)</span><span class="p" data-group-id="2076950878-2">}</span><span class="p">.</span></code></pre><p>Further imagine that some code has its own (different) definition of <code class="inline">gadget()</code>,
│ │ │ -for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="4595970206-1">(</span><span class="p" data-group-id="4595970206-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="4595970206-2">#{</span><span class="p" data-group-id="4595970206-2">}</span><span class="p">.</span></code></pre><p>Since redefinitions are allowed, the code will still compile (but with a
│ │ │ +<code class="inline">gadget()</code> defined like this:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="5550684792-1">(</span><span class="p" data-group-id="5550684792-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="5550684792-2">{</span><span class="ss">&#39;gadget&#39;</span><span class="p">,</span><span class="w"> </span><span class="nf">reference</span><span class="p" data-group-id="5550684792-3">(</span><span class="p" data-group-id="5550684792-3">)</span><span class="p" data-group-id="5550684792-2">}</span><span class="p">.</span></code></pre><p>Further imagine that some code has its own (different) definition of <code class="inline">gadget()</code>,
│ │ │ +for example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">gadget</span><span class="p" data-group-id="0513445321-1">(</span><span class="p" data-group-id="0513445321-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="0513445321-2">#{</span><span class="p" data-group-id="0513445321-2">}</span><span class="p">.</span></code></pre><p>Since redefinitions are allowed, the code will still compile (but with a
│ │ │  warning), and Dialyzer will not emit any additional warnings.</p><h2 id="type-declarations-of-user-defined-types" class="section-heading">
│ │ │    <a href="#type-declarations-of-user-defined-types" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Type Declarations of User-Defined Types</span>
│ │ │  </h2>
│ │ │  <p>As seen, the basic syntax of a type is an atom followed by closed parentheses.
│ │ │  New types are declared using <code class="inline">-type</code> and <code class="inline">-opaque</code> attributes as in the
│ │ │ -following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_struct_type</span><span class="p" data-group-id="4171158497-1">(</span><span class="p" data-group-id="4171158497-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">my_opaq_type</span><span class="p" data-group-id="4171158497-2">(</span><span class="p" data-group-id="4171158497-2">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span></code></pre><p>The type name is the atom <code class="inline">my_struct_type</code>, followed by parentheses. <code class="inline">Type</code> is a
│ │ │ +following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">my_struct_type</span><span class="p" data-group-id="7438489817-1">(</span><span class="p" data-group-id="7438489817-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">opaque</span><span class="w"> </span><span class="nf">my_opaq_type</span><span class="p" data-group-id="7438489817-2">(</span><span class="p" data-group-id="7438489817-2">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type</span><span class="p">.</span></code></pre><p>The type name is the atom <code class="inline">my_struct_type</code>, followed by parentheses. <code class="inline">Type</code> is a
│ │ │  type as defined in the previous section. A current restriction is that <code class="inline">Type</code>
│ │ │  can contain only predefined types, or user-defined types which are either of the
│ │ │  following:</p><ul><li>Module-local type, that is, with a definition that is present in the code of
│ │ │  the module</li><li>Remote type, that is, type defined in, and exported by, other modules; more
│ │ │  about this soon.</li></ul><p>For module-local types, the restriction that their definition exists in the
│ │ │  module is enforced by the compiler and results in a compilation error. (A
│ │ │  similar restriction currently exists for records.)</p><p>Type declarations can also be parameterized by including type variables between
│ │ │  the parentheses. The syntax of type variables is the same as Erlang variables,
│ │ │  that is, starts with an upper-case letter. These variables is to
│ │ │ -appear on the RHS of the definition. A concrete example follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">orddict</span><span class="p" data-group-id="7350225404-1">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="7350225404-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7350225404-2">[</span><span class="p" data-group-id="7350225404-3">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="7350225404-3">}</span><span class="p" data-group-id="7350225404-2">]</span><span class="p">.</span></code></pre><p>A module can export some types to declare that other modules are allowed to
│ │ │ -refer to them as <em>remote types</em>. This declaration has the following form:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="6271358370-1">(</span><span class="p" data-group-id="6271358370-2">[</span><span class="n">T1</span><span class="o">/</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Tk</span><span class="o">/</span><span class="n">Ak</span><span class="p" data-group-id="6271358370-2">]</span><span class="p" data-group-id="6271358370-1">)</span><span class="p">.</span></code></pre><p>Here the <code class="inline">Ti</code>s are atoms (the name of the type) and the <code class="inline">Ai</code>s are their arguments.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="6750548237-1">(</span><span class="p" data-group-id="6750548237-2">[</span><span class="ss">my_struct_type</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">orddict</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6750548237-2">]</span><span class="p" data-group-id="6750548237-1">)</span><span class="p">.</span></code></pre><p>Assuming that these types are exported from module <code class="inline">'mod'</code>, you can refer to
│ │ │ -them from other modules using remote type expressions like the following:</p><pre><code class="makeup erlang" translate="no"><span class="nc">mod</span><span class="p">:</span><span class="nf">my_struct_type</span><span class="p" data-group-id="4793850657-1">(</span><span class="p" data-group-id="4793850657-1">)</span><span class="w">
│ │ │ -</span><span class="nc">mod</span><span class="p">:</span><span class="nf">orddict</span><span class="p" data-group-id="4793850657-2">(</span><span class="nf">atom</span><span class="p" data-group-id="4793850657-3">(</span><span class="p" data-group-id="4793850657-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="4793850657-4">(</span><span class="p" data-group-id="4793850657-4">)</span><span class="p" data-group-id="4793850657-2">)</span></code></pre><p>It is not allowed to refer to types that are not declared as exported.</p><p>Types declared as <code class="inline">opaque</code> represent sets of terms whose structure is not
│ │ │ +appear on the RHS of the definition. A concrete example follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">orddict</span><span class="p" data-group-id="1795541396-1">(</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="1795541396-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="1795541396-2">[</span><span class="p" data-group-id="1795541396-3">{</span><span class="n">Key</span><span class="p">,</span><span class="w"> </span><span class="n">Val</span><span class="p" data-group-id="1795541396-3">}</span><span class="p" data-group-id="1795541396-2">]</span><span class="p">.</span></code></pre><p>A module can export some types to declare that other modules are allowed to
│ │ │ +refer to them as <em>remote types</em>. This declaration has the following form:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="1926343182-1">(</span><span class="p" data-group-id="1926343182-2">[</span><span class="n">T1</span><span class="o">/</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p">,</span><span class="w"> </span><span class="n">Tk</span><span class="o">/</span><span class="n">Ak</span><span class="p" data-group-id="1926343182-2">]</span><span class="p" data-group-id="1926343182-1">)</span><span class="p">.</span></code></pre><p>Here the <code class="inline">Ti</code>s are atoms (the name of the type) and the <code class="inline">Ai</code>s are their arguments.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">export_type</span><span class="p" data-group-id="4081740608-1">(</span><span class="p" data-group-id="4081740608-2">[</span><span class="ss">my_struct_type</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">orddict</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="4081740608-2">]</span><span class="p" data-group-id="4081740608-1">)</span><span class="p">.</span></code></pre><p>Assuming that these types are exported from module <code class="inline">'mod'</code>, you can refer to
│ │ │ +them from other modules using remote type expressions like the following:</p><pre><code class="makeup erlang" translate="no"><span class="nc">mod</span><span class="p">:</span><span class="nf">my_struct_type</span><span class="p" data-group-id="1733899843-1">(</span><span class="p" data-group-id="1733899843-1">)</span><span class="w">
│ │ │ +</span><span class="nc">mod</span><span class="p">:</span><span class="nf">orddict</span><span class="p" data-group-id="1733899843-2">(</span><span class="nf">atom</span><span class="p" data-group-id="1733899843-3">(</span><span class="p" data-group-id="1733899843-3">)</span><span class="p">,</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="1733899843-4">(</span><span class="p" data-group-id="1733899843-4">)</span><span class="p" data-group-id="1733899843-2">)</span></code></pre><p>It is not allowed to refer to types that are not declared as exported.</p><p>Types declared as <code class="inline">opaque</code> represent sets of terms whose structure is not
│ │ │  supposed to be visible from outside of their defining module. That is, only the
│ │ │  module defining them is allowed to depend on their term structure. Consequently,
│ │ │  such types do not make much sense as module local - module local types are not
│ │ │  accessible by other modules anyway - and is always to be exported.</p><p>Read more on <a href="opaques.html">Opaques</a></p><p><a href="" id="typeinrecords"></a></p><h2 id="type-information-in-record-declarations" class="section-heading">
│ │ │    <a href="#type-information-in-record-declarations" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Type Information in Record Declarations</span>
│ │ │  </h2>
│ │ │  <p>The types of record fields can be specified in the declaration of the record.
│ │ │ -The syntax for this is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8283538305-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8283538305-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="8283538305-2">}</span><span class="p" data-group-id="8283538305-1">)</span><span class="p">.</span></code></pre><p>For fields without type annotations, their type defaults to <code class="inline">any()</code>. That is, the
│ │ │ -previous example is a shorthand for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5585251466-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5585251466-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="5585251466-3">(</span><span class="p" data-group-id="5585251466-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="5585251466-2">}</span><span class="p" data-group-id="5585251466-1">)</span><span class="p">.</span></code></pre><p>In the presence of initial values for fields, the type must be declared after
│ │ │ -the initialization, as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="5206569644-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5206569644-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5206569644-3">[</span><span class="p" data-group-id="5206569644-3">]</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="5206569644-2">}</span><span class="p" data-group-id="5206569644-1">)</span><span class="p">.</span></code></pre><p>The initial values for fields are to be compatible with (that is, a member of)
│ │ │ +The syntax for this is as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1338016842-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1338016842-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="1338016842-2">}</span><span class="p" data-group-id="1338016842-1">)</span><span class="p">.</span></code></pre><p>For fields without type annotations, their type defaults to <code class="inline">any()</code>. That is, the
│ │ │ +previous example is a shorthand for the following:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="8134401372-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8134401372-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">any</span><span class="p" data-group-id="8134401372-3">(</span><span class="p" data-group-id="8134401372-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="8134401372-2">}</span><span class="p" data-group-id="8134401372-1">)</span><span class="p">.</span></code></pre><p>In the presence of initial values for fields, the type must be declared after
│ │ │ +the initialization, as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9073146822-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9073146822-2">{</span><span class="ss">field1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9073146822-3">[</span><span class="p" data-group-id="9073146822-3">]</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type1</span><span class="p">,</span><span class="w"> </span><span class="ss">field2</span><span class="p">,</span><span class="w"> </span><span class="ss">field3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="n">Type3</span><span class="p" data-group-id="9073146822-2">}</span><span class="p" data-group-id="9073146822-1">)</span><span class="p">.</span></code></pre><p>The initial values for fields are to be compatible with (that is, a member of)
│ │ │  the corresponding types. This is checked by the compiler and results in a
│ │ │  compilation error if a violation is detected.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Before Erlang/OTP 19, for fields without initial values, the singleton type
│ │ │  <code class="inline">'undefined'</code> was added to all declared types. In other words, the following
│ │ │ -two record declarations had identical effects:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7438163457-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7438163457-2">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7438163457-3">(</span><span class="p" data-group-id="7438163457-3">)</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="7438163457-4">(</span><span class="p" data-group-id="7438163457-4">)</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="7438163457-2">}</span><span class="p" data-group-id="7438163457-1">)</span><span class="p">.</span><span class="w">
│ │ │ +two record declarations had identical effects:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4638715847-1">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4638715847-2">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="4638715847-3">(</span><span class="p" data-group-id="4638715847-3">)</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="4638715847-4">(</span><span class="p" data-group-id="4638715847-4">)</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="4638715847-2">}</span><span class="p" data-group-id="4638715847-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="7438163457-5">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7438163457-6">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7438163457-7">(</span><span class="p" data-group-id="7438163457-7">)</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="7438163457-8">(</span><span class="p" data-group-id="7438163457-8">)</span><span class="p">,</span><span class="w">
│ │ │ -              </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="7438163457-6">}</span><span class="p" data-group-id="7438163457-5">)</span><span class="p">.</span></code></pre><p>This is no longer the case. If you require <code class="inline">'undefined'</code> in your record field
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="4638715847-5">(</span><span class="ss">rec</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4638715847-6">{</span><span class="ss">f1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">42</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="4638715847-7">(</span><span class="p" data-group-id="4638715847-7">)</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="ss">f2</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">float</span><span class="p" data-group-id="4638715847-8">(</span><span class="p" data-group-id="4638715847-8">)</span><span class="p">,</span><span class="w">
│ │ │ +              </span><span class="ss">f3</span><span class="w">      </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">&#39;undefined&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;a&#39;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;b&#39;</span><span class="p" data-group-id="4638715847-6">}</span><span class="p" data-group-id="4638715847-5">)</span><span class="p">.</span></code></pre><p>This is no longer the case. If you require <code class="inline">'undefined'</code> in your record field
│ │ │  type, you must explicitly add it to the typespec, as in the 2nd example.</p></section><p>Any record, containing type information or not, once defined, can be used as a
│ │ │  type using the following syntax:</p><pre><code class="text">#rec{}</code></pre><p>In addition, the record fields can be further specified when using a record type
│ │ │  by adding type information about the field as follows:</p><pre><code class="text">#rec{some_field :: Type}</code></pre><p>Any unspecified fields are assumed to have the type in the original record
│ │ │  declaration.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>When records are used to create patterns for ETS and Mnesia match functions,
│ │ │ -Dialyzer may need some help not to emit bad warnings. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="1936704143-1">(</span><span class="p" data-group-id="1936704143-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="1936704143-2">(</span><span class="p" data-group-id="1936704143-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="1936704143-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1936704143-4">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="1936704143-5">(</span><span class="p" data-group-id="1936704143-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="1936704143-6">(</span><span class="p" data-group-id="1936704143-6">)</span><span class="p" data-group-id="1936704143-4">}</span><span class="p" data-group-id="1936704143-3">)</span><span class="p">.</span><span class="w">
│ │ │ +Dialyzer may need some help not to emit bad warnings. For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="0734712373-1">(</span><span class="p" data-group-id="0734712373-1">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="0734712373-2">(</span><span class="p" data-group-id="0734712373-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="0734712373-3">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0734712373-4">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="0734712373-5">(</span><span class="p" data-group-id="0734712373-5">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="0734712373-6">(</span><span class="p" data-group-id="0734712373-6">)</span><span class="p" data-group-id="0734712373-4">}</span><span class="p" data-group-id="0734712373-3">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">lookup</span><span class="p" data-group-id="1936704143-7">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="1936704143-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="1936704143-8">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="1936704143-9">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="1936704143-9">}</span><span class="p" data-group-id="1936704143-8">)</span><span class="p">.</span></code></pre><p>Dialyzer will emit a warning since <code class="inline">'_'</code> is not in the type of record field
│ │ │ +</span><span class="nf">lookup</span><span class="p" data-group-id="0734712373-7">(</span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="n">Tab</span><span class="p" data-group-id="0734712373-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">ets</span><span class="p">:</span><span class="nf">match_object</span><span class="p" data-group-id="0734712373-8">(</span><span class="n">Tab</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0734712373-9">{</span><span class="ss">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Name</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="0734712373-9">}</span><span class="p" data-group-id="0734712373-8">)</span><span class="p">.</span></code></pre><p>Dialyzer will emit a warning since <code class="inline">'_'</code> is not in the type of record field
│ │ │  <code class="inline">height</code>.</p><p>The recommended way of dealing with this is to declare the smallest record
│ │ │  field types to accommodate all your needs, and then create refinements as
│ │ │ -needed. The modified example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="9272764369-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9272764369-2">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="9272764369-3">(</span><span class="p" data-group-id="9272764369-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="9272764369-4">(</span><span class="p" data-group-id="9272764369-4">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="9272764369-2">}</span><span class="p" data-group-id="9272764369-1">)</span><span class="p">.</span><span class="w">
│ │ │ +needed. The modified example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">record</span><span class="p" data-group-id="0536182234-1">(</span><span class="ss">person</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0536182234-2">{</span><span class="ss">name</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="0536182234-3">(</span><span class="p" data-group-id="0536182234-3">)</span><span class="p">,</span><span class="w"> </span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="0536182234-4">(</span><span class="p" data-group-id="0536182234-4">)</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">&#39;_&#39;</span><span class="p" data-group-id="0536182234-2">}</span><span class="p" data-group-id="0536182234-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">person</span><span class="p" data-group-id="9272764369-5">(</span><span class="p" data-group-id="9272764369-5">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="9272764369-6">{</span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="9272764369-7">(</span><span class="p" data-group-id="9272764369-7">)</span><span class="p" data-group-id="9272764369-6">}</span><span class="p">.</span></code></pre><p>In specifications and type declarations the type <code class="inline">person()</code> is to be preferred
│ │ │ +</span><span class="p">-</span><span class="na">type</span><span class="w"> </span><span class="nf">person</span><span class="p" data-group-id="0536182234-5">(</span><span class="p" data-group-id="0536182234-5">)</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="o">#</span><span class="ss">person</span><span class="p" data-group-id="0536182234-6">{</span><span class="ss">height</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">height</span><span class="p" data-group-id="0536182234-7">(</span><span class="p" data-group-id="0536182234-7">)</span><span class="p" data-group-id="0536182234-6">}</span><span class="p">.</span></code></pre><p>In specifications and type declarations the type <code class="inline">person()</code> is to be preferred
│ │ │  before <code class="inline">#person{}</code>.</p></section><h2 id="specifications-for-functions" class="section-heading">
│ │ │    <a href="#specifications-for-functions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Specifications for Functions</span>
│ │ │  </h2>
│ │ │  <p>A specification (or contract) for a function is given using the <code class="inline">-spec</code>
│ │ │  attribute. The general format is as follows:</p><pre><code class="text">-spec Function(ArgType1, ..., ArgTypeN) -&gt; ReturnType.</code></pre><p>An implementation of the function with the same name <code class="inline">Function</code> must exist in
│ │ │  the current module, and the arity of the function must match the number of
│ │ │  arguments, otherwise the compilation fails.</p><p>The following longer format with module name is also valid as long as <code class="inline">Module</code>
│ │ │  is the name of the current module. This can be useful for documentation
│ │ │  purposes.</p><pre><code class="text">-spec Module:Function(ArgType1, ..., ArgTypeN) -&gt; ReturnType.</code></pre><p>Also, for documentation purposes, argument names can be given:</p><pre><code class="text">-spec Function(ArgName1 :: Type1, ..., ArgNameN :: TypeN) -&gt; RT.</code></pre><p>A function specification can be overloaded. That is, it can have several types,
│ │ │ -separated by a semicolon (<code class="inline">;</code>). For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="7388502199-1">(</span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="7388502199-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T3</span><span class="p">;</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="7388502199-2">(</span><span class="n">T4</span><span class="p">,</span><span class="w"> </span><span class="n">T5</span><span class="p" data-group-id="7388502199-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T6</span><span class="p">.</span></code></pre><p>A current restriction, which currently results in a warning by Dialyzer, is that
│ │ │ +separated by a semicolon (<code class="inline">;</code>). For example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="2164322187-1">(</span><span class="n">T1</span><span class="p">,</span><span class="w"> </span><span class="n">T2</span><span class="p" data-group-id="2164322187-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T3</span><span class="p">;</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="2164322187-2">(</span><span class="n">T4</span><span class="p">,</span><span class="w"> </span><span class="n">T5</span><span class="p" data-group-id="2164322187-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">T6</span><span class="p">.</span></code></pre><p>A current restriction, which currently results in a warning by Dialyzer, is that
│ │ │  the domains of the argument types cannot overlap. For example, the following
│ │ │ -specification results in a warning:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="4724665180-1">(</span><span class="nf">pos_integer</span><span class="p" data-group-id="4724665180-2">(</span><span class="p" data-group-id="4724665180-2">)</span><span class="p" data-group-id="4724665180-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="4724665180-3">(</span><span class="p" data-group-id="4724665180-3">)</span><span class="p">;</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="4724665180-4">(</span><span class="nf">integer</span><span class="p" data-group-id="4724665180-5">(</span><span class="p" data-group-id="4724665180-5">)</span><span class="p" data-group-id="4724665180-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="4724665180-6">(</span><span class="p" data-group-id="4724665180-6">)</span><span class="p">.</span></code></pre><p>Type variables can be used in specifications to specify relations for the input
│ │ │ +specification results in a warning:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="9832023765-1">(</span><span class="nf">pos_integer</span><span class="p" data-group-id="9832023765-2">(</span><span class="p" data-group-id="9832023765-2">)</span><span class="p" data-group-id="9832023765-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="9832023765-3">(</span><span class="p" data-group-id="9832023765-3">)</span><span class="p">;</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="9832023765-4">(</span><span class="nf">integer</span><span class="p" data-group-id="9832023765-5">(</span><span class="p" data-group-id="9832023765-5">)</span><span class="p" data-group-id="9832023765-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="9832023765-6">(</span><span class="p" data-group-id="9832023765-6">)</span><span class="p">.</span></code></pre><p>Type variables can be used in specifications to specify relations for the input
│ │ │  and output arguments of a function. For example, the following specification
│ │ │  defines the type of a polymorphic identity function:</p><pre><code class="text">-spec id(X) -&gt; X.</code></pre><p>Notice that the above specification does not restrict the input and output type
│ │ │  in any way. These types can be constrained by guard-like subtype constraints and
│ │ │ -provide bounded quantification:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="5938937193-1">(</span><span class="n">X</span><span class="p" data-group-id="5938937193-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="5938937193-2">(</span><span class="p" data-group-id="5938937193-2">)</span><span class="p">.</span></code></pre><p>Currently, the <code class="inline">::</code> constraint (read as &quot;is a subtype of&quot;) is the only guard
│ │ │ +provide bounded quantification:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="2398979915-1">(</span><span class="n">X</span><span class="p" data-group-id="2398979915-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="2398979915-2">(</span><span class="p" data-group-id="2398979915-2">)</span><span class="p">.</span></code></pre><p>Currently, the <code class="inline">::</code> constraint (read as &quot;is a subtype of&quot;) is the only guard
│ │ │  constraint that can be used in the <code class="inline">when</code> part of a <code class="inline">-spec</code> attribute.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The above function specification uses multiple occurrences of the same type
│ │ │  variable. That provides more type information than the following function
│ │ │ -specification, where the type variables are missing:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="6648333047-1">(</span><span class="nf">tuple</span><span class="p" data-group-id="6648333047-2">(</span><span class="p" data-group-id="6648333047-2">)</span><span class="p" data-group-id="6648333047-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="6648333047-3">(</span><span class="p" data-group-id="6648333047-3">)</span><span class="p">.</span></code></pre><p>The latter specification says that the function takes some tuple and returns
│ │ │ +specification, where the type variables are missing:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">id</span><span class="p" data-group-id="6443192964-1">(</span><span class="nf">tuple</span><span class="p" data-group-id="6443192964-2">(</span><span class="p" data-group-id="6443192964-2">)</span><span class="p" data-group-id="6443192964-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">tuple</span><span class="p" data-group-id="6443192964-3">(</span><span class="p" data-group-id="6443192964-3">)</span><span class="p">.</span></code></pre><p>The latter specification says that the function takes some tuple and returns
│ │ │  some tuple. The specification with the <code class="inline">X</code> type variable specifies that the
│ │ │  function takes a tuple and returns <em>the same</em> tuple.</p><p>However, it is up to the tools that process the specifications to choose
│ │ │  whether to take this extra information into account or not.</p></section><p>The scope of a <code class="inline">::</code> constraint is the <code class="inline">(...) -&gt; RetType</code> specification after
│ │ │  which it appears. To avoid confusion, it is suggested that different variables
│ │ │  are used in different constituents of an overloaded contract, as shown in the
│ │ │ -following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="7417686108-1">(</span><span class="p" data-group-id="7417686108-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7417686108-3">(</span><span class="p" data-group-id="7417686108-3">)</span><span class="p" data-group-id="7417686108-2">}</span><span class="p" data-group-id="7417686108-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="7417686108-4">(</span><span class="p" data-group-id="7417686108-4">)</span><span class="p">;</span><span class="w">
│ │ │ -         </span><span class="p" data-group-id="7417686108-5">(</span><span class="p" data-group-id="7417686108-6">[</span><span class="n">Y</span><span class="p" data-group-id="7417686108-6">]</span><span class="p" data-group-id="7417686108-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="7417686108-7">(</span><span class="p" data-group-id="7417686108-7">)</span><span class="p">.</span></code></pre><p>Some functions in Erlang are not meant to return; either because they define
│ │ │ +following example:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="1953857397-1">(</span><span class="p" data-group-id="1953857397-2">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="1953857397-3">(</span><span class="p" data-group-id="1953857397-3">)</span><span class="p" data-group-id="1953857397-2">}</span><span class="p" data-group-id="1953857397-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="1953857397-4">(</span><span class="p" data-group-id="1953857397-4">)</span><span class="p">;</span><span class="w">
│ │ │ +         </span><span class="p" data-group-id="1953857397-5">(</span><span class="p" data-group-id="1953857397-6">[</span><span class="n">Y</span><span class="p" data-group-id="1953857397-6">]</span><span class="p" data-group-id="1953857397-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">number</span><span class="p" data-group-id="1953857397-7">(</span><span class="p" data-group-id="1953857397-7">)</span><span class="p">.</span></code></pre><p>Some functions in Erlang are not meant to return; either because they define
│ │ │  servers or because they are used to throw exceptions, as in the following
│ │ │ -function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_error</span><span class="p" data-group-id="0898695749-1">(</span><span class="n">Err</span><span class="p" data-group-id="0898695749-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="0898695749-2">(</span><span class="p" data-group-id="0898695749-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Err</span><span class="p" data-group-id="0898695749-3">}</span><span class="p" data-group-id="0898695749-2">)</span><span class="p">.</span></code></pre><p>For such functions, it is recommended to use the special <a href="../../erts-15.2.7.3/doc/html/erlang.html#t:no_return/0"><code class="inline">no_return/0</code></a> type
│ │ │ +function:</p><pre><code class="makeup erlang" translate="no"><span class="nf">my_error</span><span class="p" data-group-id="2657059238-1">(</span><span class="n">Err</span><span class="p" data-group-id="2657059238-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="2657059238-2">(</span><span class="p" data-group-id="2657059238-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Err</span><span class="p" data-group-id="2657059238-3">}</span><span class="p" data-group-id="2657059238-2">)</span><span class="p">.</span></code></pre><p>For such functions, it is recommended to use the special <a href="../../erts-15.2.7.3/doc/html/erlang.html#t:no_return/0"><code class="inline">no_return/0</code></a> type
│ │ │  for their &quot;return&quot;, through a contract of the following form:</p><pre><code class="text">-spec my_error(term()) -&gt; no_return().</code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Erlang uses the shorthand version <code class="inline">_</code> as an anonymous type variable equivalent
│ │ │  to <a href="../../erts-15.2.7.3/doc/html/erlang.html#t:term/0"><code class="inline">term/0</code></a> or <a href="../../erts-15.2.7.3/doc/html/erlang.html#t:any/0"><code class="inline">any/0</code></a>. For example, the following function</p><pre><code class="text">-spec Function(string(), _) -&gt; string().</code></pre><p>is equivalent to:</p><pre><code class="text">-spec Function(string(), any()) -&gt; string().</code></pre></section>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ ├── ./usr/share/doc/erlang-doc/html/doc/upcoming_incompatibilities.html
│ │ │ @@ -149,45 +149,45 @@
│ │ │  occurrences of <code class="inline">maybe</code> without quotes.</p><p><a href="" id="float_matching"></a></p><h3 id="0-0-and-0-0-will-no-longer-be-exactly-equal" class="section-heading">
│ │ │    <a href="#0-0-and-0-0-will-no-longer-be-exactly-equal" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">0.0 and -0.0 will no longer be exactly equal</span>
│ │ │  </h3>
│ │ │  <p>Currently, the floating point numbers <code class="inline">0.0</code> and <code class="inline">-0.0</code> have distinct internal
│ │ │ -representations. That can be seen if they are converted to binaries:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="4448203246-1">&lt;&lt;</span><span class="mf">0.0</span><span class="o">/</span><span class="nb">float</span><span class="p" data-group-id="4448203246-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4448203246-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="4448203246-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="p" data-group-id="4448203246-3">&lt;&lt;</span><span class="o">-</span><span class="mf">0.0</span><span class="o">/</span><span class="nb">float</span><span class="p" data-group-id="4448203246-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4448203246-4">&lt;&lt;</span><span class="mi">128</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="4448203246-4">&gt;&gt;</span></code></pre><p>However, when they are matched against each other or compared using the <code class="inline">=:=</code>
│ │ │ +representations. That can be seen if they are converted to binaries:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="p" data-group-id="7182326872-1">&lt;&lt;</span><span class="mf">0.0</span><span class="o">/</span><span class="nb">float</span><span class="p" data-group-id="7182326872-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7182326872-2">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="7182326872-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="p" data-group-id="7182326872-3">&lt;&lt;</span><span class="o">-</span><span class="mf">0.0</span><span class="o">/</span><span class="nb">float</span><span class="p" data-group-id="7182326872-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7182326872-4">&lt;&lt;</span><span class="mi">128</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="7182326872-4">&gt;&gt;</span></code></pre><p>However, when they are matched against each other or compared using the <code class="inline">=:=</code>
│ │ │  operator, they are considered to be equal. Thus, <code class="inline">0.0 =:= -0.0</code> currently
│ │ │  returns <code class="inline">true</code>.</p><p>In Erlang/OTP 27, <code class="inline">0.0 =:= -0.0</code> will return <code class="inline">false</code>, and matching <code class="inline">0.0</code> against
│ │ │  <code class="inline">-0.0</code> will fail. When used as map keys, <code class="inline">0.0</code> and <code class="inline">-0.0</code> will be considered to
│ │ │  be distinct.</p><p>The <code class="inline">==</code> operator will continue to return <code class="inline">true</code> for <code class="inline">0.0 == -0.0</code>.</p><p>To help to find code that might need to be revised, in OTP 27 there will be a
│ │ │  new compiler warning when matching against <code class="inline">0.0</code> or comparing to that value
│ │ │  using the <code class="inline">=:=</code> operator. The warning can be suppressed by matching against
│ │ │  <code class="inline">+0.0</code> instead of <code class="inline">0.0</code>.</p><p>We plan to introduce the same warning in OTP 26.1, but by default it will be
│ │ │  disabled.</p><p><a href="" id="singleton_typevars"></a></p><h3 id="singleton-type-variables-will-become-a-compile-time-error" class="section-heading">
│ │ │    <a href="#singleton-type-variables-will-become-a-compile-time-error" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Singleton type variables will become a compile-time error</span>
│ │ │  </h3>
│ │ │ -<p>Before Erlang/OTP 26, the compiler would silenty accept the following spec:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="9668833145-1">(</span><span class="n">Opts</span><span class="p" data-group-id="9668833145-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="9668833145-2">(</span><span class="p" data-group-id="9668833145-2">)</span><span class="w"> </span><span class="k">when</span><span class="w">
│ │ │ -    </span><span class="n">Opts</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="9668833145-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Unknown</span><span class="p" data-group-id="9668833145-3">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="9668833145-4">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Unknown</span><span class="p" data-group-id="9668833145-4">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">f</span><span class="p" data-group-id="9668833145-5">(</span><span class="p">_</span><span class="p" data-group-id="9668833145-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">error</span><span class="p">.</span></code></pre><p>In OTP 26, the compiler emits a warning pointing out that the type variable
│ │ │ -<code class="inline">Unknown</code> is unbound:</p><pre><code class="makeup erlang" translate="no"><span class="ss">t</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">6</span><span class="p">:</span><span class="mi">18</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="ss">variable</span><span class="w"> </span><span class="ss">&#39;Unknown&#39;</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">only</span><span class="w"> </span><span class="ss">used</span><span class="w"> </span><span class="nf">once</span><span class="w"> </span><span class="p" data-group-id="6304568471-1">(</span><span class="ss">is</span><span class="w"> </span><span class="ss">unbound</span><span class="p" data-group-id="6304568471-1">)</span><span class="w">
│ │ │ +<p>Before Erlang/OTP 26, the compiler would silenty accept the following spec:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">spec</span><span class="w"> </span><span class="nf">f</span><span class="p" data-group-id="7753550312-1">(</span><span class="n">Opts</span><span class="p" data-group-id="7753550312-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">term</span><span class="p" data-group-id="7753550312-2">(</span><span class="p" data-group-id="7753550312-2">)</span><span class="w"> </span><span class="k">when</span><span class="w">
│ │ │ +    </span><span class="n">Opts</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="p" data-group-id="7753550312-3">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Unknown</span><span class="p" data-group-id="7753550312-3">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="7753550312-4">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Unknown</span><span class="p" data-group-id="7753550312-4">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">f</span><span class="p" data-group-id="7753550312-5">(</span><span class="p">_</span><span class="p" data-group-id="7753550312-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">error</span><span class="p">.</span></code></pre><p>In OTP 26, the compiler emits a warning pointing out that the type variable
│ │ │ +<code class="inline">Unknown</code> is unbound:</p><pre><code class="makeup erlang" translate="no"><span class="ss">t</span><span class="p">.</span><span class="nc">erl</span><span class="p">:</span><span class="mi">6</span><span class="p">:</span><span class="mi">18</span><span class="p">:</span><span class="w"> </span><span class="n">Warning</span><span class="p">:</span><span class="w"> </span><span class="ss">type</span><span class="w"> </span><span class="ss">variable</span><span class="w"> </span><span class="ss">&#39;Unknown&#39;</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">only</span><span class="w"> </span><span class="ss">used</span><span class="w"> </span><span class="nf">once</span><span class="w"> </span><span class="p" data-group-id="3400311292-1">(</span><span class="ss">is</span><span class="w"> </span><span class="ss">unbound</span><span class="p" data-group-id="3400311292-1">)</span><span class="w">
│ │ │  </span><span class="c1">%    6|     Opts :: {ok, Unknown} | {error, Unknown}.</span><span class="w">
│ │ │  </span><span class="c1">%     |                  ^</span></code></pre><p>In OTP 27, that warning will become an error.</p><p><a href="" id="escripts_will_be_compiled"></a></p><h3 id="escripts-will-be-compiled-by-default" class="section-heading">
│ │ │    <a href="#escripts-will-be-compiled-by-default" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Escripts will be compiled by default</span>
│ │ │  </h3>
│ │ │  <p>Escripts will be compiled by default instead of interpreted. That means that the
│ │ │  <code class="inline">compiler</code> application must be available.</p><p>The old behavior of interpreting escripts can be restored by adding the
│ │ │ -following line to the script file:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">mode</span><span class="p" data-group-id="7832542997-1">(</span><span class="ss">interpret</span><span class="p" data-group-id="7832542997-1">)</span><span class="p">.</span></code></pre><p>In OTP 28, support for interpreting an escript will be removed.</p><h3 id="code_path_choice-will-default-to-strict" class="section-heading">
│ │ │ +following line to the script file:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">mode</span><span class="p" data-group-id="8961332509-1">(</span><span class="ss">interpret</span><span class="p" data-group-id="8961332509-1">)</span><span class="p">.</span></code></pre><p>In OTP 28, support for interpreting an escript will be removed.</p><h3 id="code_path_choice-will-default-to-strict" class="section-heading">
│ │ │    <a href="#code_path_choice-will-default-to-strict" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">-code_path_choice will default to strict</span>
│ │ │  </h3>
│ │ │  <p>This command line option controls if paths given in the command line, boot
│ │ │  scripts, and the code server should be interpreted as is strict or relaxed.</p><p>OTP 26 and earlier defaults to <code class="inline">relaxed</code>, which means <code class="inline">-pa myapp/ebin</code> would
│ │ │ @@ -231,18 +231,18 @@
│ │ │  &quot;
│ │ │  String Content
│ │ │  &quot;
│ │ │  %%
│ │ │  %% In OTP 27 it is instead interpreted as a
│ │ │  %% Triple-Quoted String equivalent to
│ │ │  &quot;String Content&quot;</code></pre><pre><code class="makeup erlang" translate="no"><span class="s">&quot;&quot;</span><span class="s">&quot;&quot;</span><span class="w">
│ │ │ -</span><span class="o">++</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="9917428771-1">(</span><span class="p" data-group-id="9917428771-1">)</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │ +</span><span class="o">++</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="9386007567-1">(</span><span class="p" data-group-id="9386007567-1">)</span><span class="w"> </span><span class="o">++</span><span class="w">
│ │ │  </span><span class="s">&quot;&quot;</span><span class="s">&quot;&quot;</span><span class="w">
│ │ │  </span><span class="c1">%% Became</span><span class="w">
│ │ │ -</span><span class="s">&quot;&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="9917428771-2">(</span><span class="p" data-group-id="9917428771-2">)</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="w">
│ │ │ +</span><span class="s">&quot;&quot;</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="nf">foo</span><span class="p" data-group-id="9386007567-2">(</span><span class="p" data-group-id="9386007567-2">)</span><span class="w"> </span><span class="o">++</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="w">
│ │ │  </span><span class="c1">%%</span><span class="w">
│ │ │  </span><span class="c1">%% In OTP 27 it is instead interpreted as a</span><span class="w">
│ │ │  </span><span class="c1">%% Triple-Quoted String (triple-or-more) equivalent to</span><span class="w">
│ │ │  </span><span class="s">&quot;++ foo() ++&quot;</span></code></pre><p>From Erlang/OTP 26.1 up to 27.0 the compiler issues a warning for a sequence of
│ │ │  3 or more double-quote characters since that is almost certainly a mistake or
│ │ │  something like a result of bad automatic code generation. If a users gets that
│ │ │  warning, the code should be corrected for example by inserting appropriate
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/.build
│ │ │ @@ -42,15 +42,15 @@
│ │ │  dist/lato-latin-300-normal-YUMVEFOL.woff2
│ │ │  dist/lato-latin-400-normal-W7754I4D.woff2
│ │ │  dist/lato-latin-700-normal-2XVSBPG4.woff2
│ │ │  dist/lato-latin-ext-300-normal-VPGGJKJL.woff2
│ │ │  dist/lato-latin-ext-400-normal-N27NCBWW.woff2
│ │ │  dist/lato-latin-ext-700-normal-Q2L5DVMW.woff2
│ │ │  dist/remixicon-NKANDIL5.woff2
│ │ │ -dist/search_data-24AC38FF.js
│ │ │ +dist/search_data-DCEA5CE3.js
│ │ │  dist/sidebar_items-0A25BDF1.js
│ │ │  driver.html
│ │ │  driver_entry.html
│ │ │  epmd_cmd.html
│ │ │  erl_cmd.html
│ │ │  erl_dist_protocol.html
│ │ │  erl_driver.html
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/alt_dist.html
│ │ │ @@ -237,50 +237,50 @@
│ │ │  <code class="inline">uds_dist</code> example using a port driver written in C, <code class="inline">erl_uds_dist</code> is written
│ │ │  entirely in Erlang.</p><h3 id="exported-callback-functions" class="section-heading">
│ │ │    <a href="#exported-callback-functions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Exported Callback Functions</span>
│ │ │  </h3>
│ │ │ -<p>The following functions are mandatory:</p><ul><li><pre id="listen"><code class="makeup erlang" translate="no"><span class="nf">listen</span><span class="p" data-group-id="4856801138-1">(</span><span class="n">Name</span><span class="p" data-group-id="4856801138-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="err"> </span><span class="err"> </span><span class="p" data-group-id="4856801138-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4856801138-3">{</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p">,</span><span class="w"> </span><span class="n">Creation</span><span class="p" data-group-id="4856801138-3">}</span><span class="p" data-group-id="4856801138-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="4856801138-4">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="4856801138-4">}</span><span class="w">
│ │ │ -</span><span class="nf">listen</span><span class="p" data-group-id="4856801138-5">(</span><span class="n">Name</span><span class="p">,</span><span class="n">Host</span><span class="p" data-group-id="4856801138-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="err"> </span><span class="err"> </span><span class="p" data-group-id="4856801138-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4856801138-7">{</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p">,</span><span class="w"> </span><span class="n">Creation</span><span class="p" data-group-id="4856801138-7">}</span><span class="p" data-group-id="4856801138-6">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="4856801138-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="4856801138-8">}</span></code></pre><p><code class="inline">listen/2</code> is called once in order to listen for incoming connection requests.
│ │ │ +<p>The following functions are mandatory:</p><ul><li><pre id="listen"><code class="makeup erlang" translate="no"><span class="nf">listen</span><span class="p" data-group-id="0088980090-1">(</span><span class="n">Name</span><span class="p" data-group-id="0088980090-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="err"> </span><span class="err"> </span><span class="p" data-group-id="0088980090-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0088980090-3">{</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p">,</span><span class="w"> </span><span class="n">Creation</span><span class="p" data-group-id="0088980090-3">}</span><span class="p" data-group-id="0088980090-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="0088980090-4">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="0088980090-4">}</span><span class="w">
│ │ │ +</span><span class="nf">listen</span><span class="p" data-group-id="0088980090-5">(</span><span class="n">Name</span><span class="p">,</span><span class="n">Host</span><span class="p" data-group-id="0088980090-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="err"> </span><span class="err"> </span><span class="p" data-group-id="0088980090-6">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0088980090-7">{</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Address</span><span class="p">,</span><span class="w"> </span><span class="n">Creation</span><span class="p" data-group-id="0088980090-7">}</span><span class="p" data-group-id="0088980090-6">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="0088980090-8">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="0088980090-8">}</span></code></pre><p><code class="inline">listen/2</code> is called once in order to listen for incoming connection requests.
│ │ │  The call is made when the distribution is brought up. The argument <code class="inline">Name</code> is
│ │ │  the part of the node name before the <code class="inline">@</code> sign in the full node name. It can be
│ │ │  either an atom or a string. The argument <code class="inline">Host</code> is the part of the node name
│ │ │  after the <code class="inline">@</code> sign in the full node name. It is always a string.</p><p>The return value consists of a <code class="inline">Listen</code> handle (which is later passed to the
│ │ │  <a href="alt_dist.html#accept"><code class="inline">accept/1</code></a> callback), <code class="inline">Address</code> which is a
│ │ │  <code class="inline">#net_address{}</code> record with information about the address for the node (the
│ │ │  <code class="inline">#net_address{}</code> record is defined in <code class="inline">kernel/include/net_address.hrl</code>), and
│ │ │  <code class="inline">Creation</code> which (currently) is an integer <code class="inline">1</code>, <code class="inline">2</code>, or <code class="inline">3</code>.</p><p>If <a href="epmd_cmd.html"><code class="inline">epmd</code></a> is to be used for node discovery, you typically want
│ │ │  to use the <code class="inline">erl_epmd</code> module (part of the <code class="inline">kernel</code> application) in order to
│ │ │ -register the listen port with <code class="inline">epmd</code> and retrieve <code class="inline">Creation</code> to use.</p></li><li><pre id="address"><code class="makeup erlang" translate="no"><span class="nf">address</span><span class="p" data-group-id="9229424460-1">(</span><span class="p" data-group-id="9229424460-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +register the listen port with <code class="inline">epmd</code> and retrieve <code class="inline">Creation</code> to use.</p></li><li><pre id="address"><code class="makeup erlang" translate="no"><span class="nf">address</span><span class="p" data-group-id="5628196768-1">(</span><span class="p" data-group-id="5628196768-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="err"> </span><span class="err"> </span><span class="n">Address</span></code></pre><p><code class="inline">address/0</code> is called in order to get the <code class="inline">Address</code> part of the
│ │ │  <a href="alt_dist.html#listen"><code class="inline">listen/2</code></a> function without creating a listen socket.
│ │ │ -All fields except <code class="inline">address</code> have to be set in the returned record</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">address</span><span class="p" data-group-id="2303399482-1">(</span><span class="p" data-group-id="2303399482-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2303399482-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Host</span><span class="p" data-group-id="2303399482-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">inet</span><span class="p">:</span><span class="nf">gethostname</span><span class="p" data-group-id="2303399482-3">(</span><span class="p" data-group-id="2303399482-3">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="o">#</span><span class="ss">net_address</span><span class="p" data-group-id="2303399482-4">{</span><span class="w"> </span><span class="ss">host</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Host</span><span class="p">,</span><span class="w"> </span><span class="ss">protocol</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">tcp</span><span class="p">,</span><span class="w"> </span><span class="ss">family</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">inet6</span><span class="w"> </span><span class="p" data-group-id="2303399482-4">}</span><span class="p">.</span></code></pre></li><li><pre id="accept"><code class="makeup erlang" translate="no"><span class="nf">accept</span><span class="p" data-group-id="4164198328-1">(</span><span class="n">Listen</span><span class="p" data-group-id="4164198328-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +All fields except <code class="inline">address</code> have to be set in the returned record</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">address</span><span class="p" data-group-id="4885914991-1">(</span><span class="p" data-group-id="4885914991-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4885914991-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Host</span><span class="p" data-group-id="4885914991-2">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">inet</span><span class="p">:</span><span class="nf">gethostname</span><span class="p" data-group-id="4885914991-3">(</span><span class="p" data-group-id="4885914991-3">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="o">#</span><span class="ss">net_address</span><span class="p" data-group-id="4885914991-4">{</span><span class="w"> </span><span class="ss">host</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Host</span><span class="p">,</span><span class="w"> </span><span class="ss">protocol</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">tcp</span><span class="p">,</span><span class="w"> </span><span class="ss">family</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">inet6</span><span class="w"> </span><span class="p" data-group-id="4885914991-4">}</span><span class="p">.</span></code></pre></li><li><pre id="accept"><code class="makeup erlang" translate="no"><span class="nf">accept</span><span class="p" data-group-id="2669490302-1">(</span><span class="n">Listen</span><span class="p" data-group-id="2669490302-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="err"> </span><span class="err"> </span><span class="n">AcceptorPid</span></code></pre><p><code class="inline">accept/1</code> should spawn a process that accepts connections. This process
│ │ │  should preferably execute on <code class="inline">max</code> priority. The process identifier of this
│ │ │  process should be returned.</p><p>The <code class="inline">Listen</code> argument will be the same as the <code class="inline">Listen</code> handle part of the
│ │ │  return value of the <a href="alt_dist.html#listen"><code class="inline">listen/1</code></a> callback above.
│ │ │  <code class="inline">accept/1</code> is called only once when the distribution protocol is started.</p><p>The caller of this function is a representative for <code class="inline">net_kernel</code> (this may or
│ │ │  may not be the process registered as <code class="inline">net_kernel</code>) and is in this document
│ │ │  identified as <code class="inline">Kernel</code>. When a connection has been accepted by the acceptor
│ │ │  process, it needs to inform <code class="inline">Kernel</code> about the accepted connection. This is
│ │ │ -done by passing a message on the form:</p><pre><code class="makeup erlang" translate="no"><span class="n">Kernel</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="8067739683-1">{</span><span class="ss">accept</span><span class="p">,</span><span class="w"> </span><span class="n">AcceptorPid</span><span class="p">,</span><span class="w"> </span><span class="n">DistController</span><span class="p">,</span><span class="w"> </span><span class="n">Family</span><span class="p">,</span><span class="w"> </span><span class="n">Proto</span><span class="p" data-group-id="8067739683-1">}</span></code></pre><p><code class="inline">DistController</code> is either the process or port identifier of the distribution
│ │ │ +done by passing a message on the form:</p><pre><code class="makeup erlang" translate="no"><span class="n">Kernel</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="2795189782-1">{</span><span class="ss">accept</span><span class="p">,</span><span class="w"> </span><span class="n">AcceptorPid</span><span class="p">,</span><span class="w"> </span><span class="n">DistController</span><span class="p">,</span><span class="w"> </span><span class="n">Family</span><span class="p">,</span><span class="w"> </span><span class="n">Proto</span><span class="p" data-group-id="2795189782-1">}</span></code></pre><p><code class="inline">DistController</code> is either the process or port identifier of the distribution
│ │ │  controller for the connection. The distribution controller should be created
│ │ │  by the acceptor processes when a new connection is accepted. Its job is to
│ │ │  dispatch traffic on the connection.</p><p><code class="inline">Kernel</code> responds with one of the following messages:</p><ul><li><p><strong><code class="inline">{Kernel, controller, SupervisorPid}</code></strong> - The request was accepted and
│ │ │  <code class="inline">SupervisorPid</code> is the process identifier of the connection supervisor
│ │ │  process (which is created in the
│ │ │  <a href="alt_dist.html#accept_connection"><code class="inline">accept_connection/5</code></a> callback).</p></li><li><p><strong><code class="inline">{Kernel, unsupported_protocol}</code></strong> - The request was rejected. This is a
│ │ │  fatal error. The acceptor process should terminate.</p></li></ul><p>When an accept sequence has been completed the acceptor process is expected to
│ │ │ -continue accepting further requests.</p></li><li><pre id="accept_connection"><code class="makeup erlang" translate="no"><span class="nf">accept_connection</span><span class="p" data-group-id="9128116939-1">(</span><span class="n">AcceptorPid</span><span class="p">,</span><span class="w"> </span><span class="n">DistCtrl</span><span class="p">,</span><span class="w"> </span><span class="n">MyNode</span><span class="p">,</span><span class="w"> </span><span class="n">Allowed</span><span class="p">,</span><span class="w"> </span><span class="n">SetupTime</span><span class="p" data-group-id="9128116939-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +continue accepting further requests.</p></li><li><pre id="accept_connection"><code class="makeup erlang" translate="no"><span class="nf">accept_connection</span><span class="p" data-group-id="1745590260-1">(</span><span class="n">AcceptorPid</span><span class="p">,</span><span class="w"> </span><span class="n">DistCtrl</span><span class="p">,</span><span class="w"> </span><span class="n">MyNode</span><span class="p">,</span><span class="w"> </span><span class="n">Allowed</span><span class="p">,</span><span class="w"> </span><span class="n">SetupTime</span><span class="p" data-group-id="1745590260-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="err"> </span><span class="err"> </span><span class="n">ConnectionSupervisorPid</span></code></pre><p><code class="inline">accept_connection/5</code> should spawn a process that will perform the Erlang
│ │ │  distribution handshake for the connection. If the handshake successfully
│ │ │  completes it should continue to function as a connection supervisor. This
│ │ │  process should preferably execute on <code class="inline">max</code> priority and should be linked to
│ │ │  the caller. The <code class="inline">dist_util:net_ticker_spawn_options()</code> function can be called
│ │ │  to get spawn options suitable for this process which can be passed directly to
│ │ │  <a href="erlang.html#spawn_opt/4"><code class="inline">erlang:spawn_opt/4</code></a>. <code class="inline">dist_util:net_ticker_spawn_options()</code> will by default
│ │ │ @@ -294,15 +294,15 @@
│ │ │  <code class="inline">dist_util:handshake_other_started(HsData)</code>.</p></li><li><p><strong><code class="inline">Allowed</code></strong> - To be passed along to
│ │ │  <code class="inline">dist_util:handshake_other_started(HsData)</code>.</p></li><li><p><strong><code class="inline">SetupTime</code></strong> - Time used for creating a setup timer by a call to
│ │ │  <code class="inline">dist_util:start_timer(SetupTime)</code>. The timer should be passed along to
│ │ │  <code class="inline">dist_util:handshake_other_started(HsData)</code>.</p></li></ul><p>The created process should provide callbacks and other information needed for
│ │ │  the handshake in a <a href="alt_dist.html#hs_data_record"><code class="inline">#hs_data{}</code></a> record and call
│ │ │  <code class="inline">dist_util:handshake_other_started(HsData)</code> with this record.</p><p><code class="inline">dist_util:handshake_other_started(HsData)</code> will perform the handshake and if
│ │ │  the handshake successfully completes this process will then continue in a
│ │ │ -connection supervisor loop as long as the connection is up.</p></li><li><pre id="setup"><code class="makeup erlang" translate="no"><span class="nf">setup</span><span class="p" data-group-id="1009438358-1">(</span><span class="n">Node</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">MyNode</span><span class="p">,</span><span class="w"> </span><span class="n">LongOrShortNames</span><span class="p">,</span><span class="w"> </span><span class="n">SetupTime</span><span class="p" data-group-id="1009438358-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +connection supervisor loop as long as the connection is up.</p></li><li><pre id="setup"><code class="makeup erlang" translate="no"><span class="nf">setup</span><span class="p" data-group-id="4602547400-1">(</span><span class="n">Node</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">MyNode</span><span class="p">,</span><span class="w"> </span><span class="n">LongOrShortNames</span><span class="p">,</span><span class="w"> </span><span class="n">SetupTime</span><span class="p" data-group-id="4602547400-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │  </span><span class="err"> </span><span class="err"> </span><span class="n">ConnectionSupervisorPid</span></code></pre><p><code class="inline">setup/5</code> should spawn a process that connects to <code class="inline">Node</code>. When connection has
│ │ │  been established it should perform the Erlang distribution handshake for the
│ │ │  connection. If the handshake successfully completes it should continue to
│ │ │  function as a connection supervisor. This process should preferably execute on
│ │ │  <code class="inline">max</code> priority and should be linked to the caller. The
│ │ │  <code class="inline">dist_util:net_ticker_spawn_options()</code> function can be called to get spawn
│ │ │  options suitable for this process which can be passed directly to
│ │ │ @@ -320,23 +320,23 @@
│ │ │  may not be the process registered as <code class="inline">net_kernel</code>) and is in this document
│ │ │  identified as <code class="inline">Kernel</code>.</p><p>This function should, besides spawning the connection supervisor, also create
│ │ │  a distribution controller. The distribution controller is either a process or
│ │ │  a port which is responsible for dispatching traffic.</p><p>The created process should provide callbacks and other information needed for
│ │ │  the handshake in a <a href="alt_dist.html#hs_data_record"><code class="inline">#hs_data{}</code></a> record and call
│ │ │  <code class="inline">dist_util:handshake_we_started(HsData)</code> with this record.</p><p><code class="inline">dist_util:handshake_we_started(HsData)</code> will perform the handshake and the
│ │ │  handshake successfully completes this process will then continue in a
│ │ │ -connection supervisor loop as long as the connection is up.</p></li><li><pre id="close"><code class="makeup erlang" translate="no"><span class="nf">close</span><span class="p" data-group-id="3582297346-1">(</span><span class="n">Listen</span><span class="p" data-group-id="3582297346-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="err"> </span><span class="err"> </span><span class="nf">void</span><span class="p" data-group-id="3582297346-2">(</span><span class="p" data-group-id="3582297346-2">)</span></code></pre><p>Called in order to close the <code class="inline">Listen</code> handle that originally was passed from
│ │ │ -the <a href="alt_dist.html#listen"><code class="inline">listen/1</code></a> callback.</p></li><li><pre id="select"><code class="makeup erlang" translate="no"><span class="nf">select</span><span class="p" data-group-id="5456605182-1">(</span><span class="n">NodeName</span><span class="p" data-group-id="5456605182-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="err"> </span><span class="err"> </span><span class="nf">boolean</span><span class="p" data-group-id="5456605182-2">(</span><span class="p" data-group-id="5456605182-2">)</span></code></pre><p>Return <code class="inline">true</code> if the host name part of the <code class="inline">NodeName</code> is valid for use with
│ │ │ -this protocol; otherwise, <code class="inline">false</code>.</p></li></ul><p>There are also two optional functions that may be exported:</p><ul><li><pre id="setopts"><code class="makeup erlang" translate="no"><span class="nf">setopts</span><span class="p" data-group-id="3396732817-1">(</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="3396732817-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="err"> </span><span class="err"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="3396732817-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="3396732817-2">}</span></code></pre><p>The argument <code class="inline">Listen</code> is the handle originally passed from the
│ │ │ +connection supervisor loop as long as the connection is up.</p></li><li><pre id="close"><code class="makeup erlang" translate="no"><span class="nf">close</span><span class="p" data-group-id="2970060026-1">(</span><span class="n">Listen</span><span class="p" data-group-id="2970060026-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="err"> </span><span class="err"> </span><span class="nf">void</span><span class="p" data-group-id="2970060026-2">(</span><span class="p" data-group-id="2970060026-2">)</span></code></pre><p>Called in order to close the <code class="inline">Listen</code> handle that originally was passed from
│ │ │ +the <a href="alt_dist.html#listen"><code class="inline">listen/1</code></a> callback.</p></li><li><pre id="select"><code class="makeup erlang" translate="no"><span class="nf">select</span><span class="p" data-group-id="0343267906-1">(</span><span class="n">NodeName</span><span class="p" data-group-id="0343267906-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="err"> </span><span class="err"> </span><span class="nf">boolean</span><span class="p" data-group-id="0343267906-2">(</span><span class="p" data-group-id="0343267906-2">)</span></code></pre><p>Return <code class="inline">true</code> if the host name part of the <code class="inline">NodeName</code> is valid for use with
│ │ │ +this protocol; otherwise, <code class="inline">false</code>.</p></li></ul><p>There are also two optional functions that may be exported:</p><ul><li><pre id="setopts"><code class="makeup erlang" translate="no"><span class="nf">setopts</span><span class="p" data-group-id="9811536199-1">(</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9811536199-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="err"> </span><span class="err"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="9811536199-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="9811536199-2">}</span></code></pre><p>The argument <code class="inline">Listen</code> is the handle originally passed from the
│ │ │  <a href="alt_dist.html#listen"><code class="inline">listen/1</code></a> callback. The argument <code class="inline">Opts</code> is a list of
│ │ │ -options to set on future connections.</p></li><li><pre id="getopts"><code class="makeup erlang" translate="no"><span class="nf">getopts</span><span class="p" data-group-id="7768915617-1">(</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="7768915617-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -</span><span class="err"> </span><span class="err"> </span><span class="p" data-group-id="7768915617-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">OptionValues</span><span class="p" data-group-id="7768915617-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="7768915617-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="7768915617-3">}</span></code></pre><p>The argument <code class="inline">Listen</code> is the handle originally passed from the
│ │ │ +options to set on future connections.</p></li><li><pre id="getopts"><code class="makeup erlang" translate="no"><span class="nf">getopts</span><span class="p" data-group-id="9704714639-1">(</span><span class="n">Listen</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="9704714639-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="err"> </span><span class="err"> </span><span class="p" data-group-id="9704714639-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">OptionValues</span><span class="p" data-group-id="9704714639-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="9704714639-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="9704714639-3">}</span></code></pre><p>The argument <code class="inline">Listen</code> is the handle originally passed from the
│ │ │  <a href="alt_dist.html#listen"><code class="inline">listen/1</code></a> callback. The argument <code class="inline">Opts</code> is a list of
│ │ │  options to read for future connections.</p></li></ul><p><a href="" id="hs_data_record"></a></p><h3 id="the-hs_data-record" class="section-heading">
│ │ │    <a href="#the-hs_data-record" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">The #hs_data{} Record</span>
│ │ │  </h3>
│ │ │ @@ -350,44 +350,44 @@
│ │ │  <a href="alt_dist.html#accept_connection"><code class="inline">accept_connection/5</code></a>.</p></li><li><p><strong><code class="inline" id="hs_data_other_node">other_node</code></strong> - Name of the other node. This field
│ │ │  is only mandatory when this node initiates the connection. That is, when
│ │ │  connection is set up via <a href="alt_dist.html#setup"><code class="inline">setup/5</code></a>.</p></li><li><p><strong><code class="inline" id="hs_data_this_node">this_node</code></strong> - The node name of this node.</p></li><li><p><strong><code class="inline" id="hs_data_socket">socket</code></strong> - The identifier of the distribution
│ │ │  controller.</p></li><li><p><strong><code class="inline" id="hs_data_timer">timer</code></strong> - The timer created using
│ │ │  <code class="inline">dist_util:start_timer/1</code>.</p></li><li><p><strong><code class="inline" id="hs_data_allowed">allowed</code></strong> - Information passed as <code class="inline">Allowed</code> to
│ │ │  <code class="inline">accept_connection/5</code>. This field is only mandatory when the remote node
│ │ │  initiated the connection. That is, when the connection is set up via
│ │ │ -<a href="alt_dist.html#accept_connection"><code class="inline">accept_connection/5</code></a>.</p></li><li><p><strong><code class="inline" id="hs_data_f_send">f_send</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="9932454359-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9932454359-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="9932454359-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="9932454359-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">Data</code>
│ │ │ -is io data to pass to the other side.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_recv">f_recv</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2349367010-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="2349367010-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2349367010-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Packet</span><span class="p" data-group-id="2349367010-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="2349367010-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="2349367010-3">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. If
│ │ │ +<a href="alt_dist.html#accept_connection"><code class="inline">accept_connection/5</code></a>.</p></li><li><p><strong><code class="inline" id="hs_data_f_send">f_send</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="4172032150-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="4172032150-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="4172032150-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="4172032150-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">Data</code>
│ │ │ +is io data to pass to the other side.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_recv">f_recv</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="0527928222-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Length</span><span class="p" data-group-id="0527928222-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="0527928222-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Packet</span><span class="p" data-group-id="0527928222-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="0527928222-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Reason</span><span class="p" data-group-id="0527928222-3">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. If
│ │ │  <code class="inline">Length</code> is <code class="inline">0</code>, all available bytes should be returned. If <code class="inline">Length &gt; 0</code>,
│ │ │  exactly <code class="inline">Length</code> bytes should be returned, or an error; possibly discarding
│ │ │  less than <code class="inline">Length</code> bytes of data when the connection is closed from the other
│ │ │  side. It is used for passive receive of data from the other end.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_setopts_pre_nodeup">f_setopts_pre_nodeup</code></strong> - A fun with the
│ │ │ -following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="8535584475-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="8535584475-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="8535584475-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="8535584475-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. Called
│ │ │ +following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="1466862915-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="1466862915-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="1466862915-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="1466862915-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. Called
│ │ │  just before the distribution channel is taken up for normal traffic.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_setopts_post_nodeup">f_setopts_post_nodeup</code></strong> - A fun with
│ │ │ -the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="8692467451-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="8692467451-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="8692467451-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="8692467451-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. Called
│ │ │ -just after distribution channel has been taken up for normal traffic.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_getll">f_getll</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="0837920773-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="0837920773-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">ID</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">ID</code> is
│ │ │ +the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2324386575-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="2324386575-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="2324386575-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="2324386575-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. Called
│ │ │ +just after distribution channel has been taken up for normal traffic.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_getll">f_getll</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="0617019714-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="0617019714-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">ID</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">ID</code> is
│ │ │  the identifier of the low level entity that handles the connection (often
│ │ │ -<code class="inline">DistCtrlr</code> itself).</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_address">f_address</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="5898554889-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="5898554889-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">NetAddress</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller, <code class="inline">Node</code> is
│ │ │ +<code class="inline">DistCtrlr</code> itself).</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_f_address">f_address</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="7355763665-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p" data-group-id="7355763665-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">NetAddress</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller, <code class="inline">Node</code> is
│ │ │  the node name of the node on the other end, and <code class="inline">NetAddress</code> is a
│ │ │  <code class="inline">#net_address{}</code> record with information about the address for the <code class="inline">Node</code> on
│ │ │  the other end of the connection. The <code class="inline">#net_address{}</code> record is defined in
│ │ │ -<code class="inline">kernel/include/net_address.hrl</code>.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_mf_tick">mf_tick</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3648043252-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="3648043252-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">void</span><span class="p" data-group-id="3648043252-2">(</span><span class="p" data-group-id="3648043252-2">)</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. This
│ │ │ +<code class="inline">kernel/include/net_address.hrl</code>.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_mf_tick">mf_tick</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3289210364-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="3289210364-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">void</span><span class="p" data-group-id="3289210364-2">(</span><span class="p" data-group-id="3289210364-2">)</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller. This
│ │ │  function should send information over the connection that is not interpreted
│ │ │  by the other end while increasing the statistics of received packets on the
│ │ │  other end. This is usually implemented by sending an empty packet.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>It is of vital importance that this operation does not block the caller for
│ │ │ -a long time. This since it is called from the connection supervisor.</p></section><p>Used when connection is up.</p></li><li><p><strong><code class="inline" id="hs_data_mf_getstat">mf_getstat</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="7055272001-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="7055272001-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7055272001-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Received</span><span class="p">,</span><span class="w"> </span><span class="n">Sent</span><span class="p">,</span><span class="w"> </span><span class="n">PendSend</span><span class="p" data-group-id="7055272001-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller, <code class="inline">Received</code>
│ │ │ +a long time. This since it is called from the connection supervisor.</p></section><p>Used when connection is up.</p></li><li><p><strong><code class="inline" id="hs_data_mf_getstat">mf_getstat</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="6371400446-1">(</span><span class="n">DistCtrlr</span><span class="p" data-group-id="6371400446-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6371400446-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Received</span><span class="p">,</span><span class="w"> </span><span class="n">Sent</span><span class="p">,</span><span class="w"> </span><span class="n">PendSend</span><span class="p" data-group-id="6371400446-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller, <code class="inline">Received</code>
│ │ │  is received packets, <code class="inline">Sent</code> is sent packets, and <code class="inline">PendSend</code> is amount of data
│ │ │  in queue to be sent (typically in bytes, but <code class="inline">dist_util</code> only checks whether
│ │ │  the value is non-zero to know there is data in queue) or a <a href="erlang.html#t:boolean/0"><code class="inline">boolean/0</code></a>
│ │ │  indicating whether there are packets in queue to be sent.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>It is of vital importance that this operation does not block the caller for
│ │ │  a long time. This since it is called from the connection supervisor.</p></section><p>Used when connection is up.</p></li><li><p><strong><code class="inline" id="hs_data_request_type">request_type</code></strong> - The request <code class="inline">Type</code> as passed to
│ │ │  <a href="alt_dist.html#setup"><code class="inline">setup/5</code></a>. This is only mandatory when the connection has
│ │ │ -been initiated by this node. That is, the connection is set up via <code class="inline">setup/5</code>.</p></li><li><p><strong><code class="inline" id="hs_data_mf_setopts">mf_setopts</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3168536327-1">(</span><span class="n">DistCtrl</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="3168536327-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="3168536327-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="3168536327-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">Opts</code>
│ │ │ -is a list of options to set on the connection.</p><p>This function is optional. Used when connection is up.</p></li><li><p><strong><code class="inline" id="hs_data_mf_getopts">mf_getopts</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="3964596681-1">(</span><span class="n">DistCtrl</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="3964596681-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3964596681-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">OptionValues</span><span class="p" data-group-id="3964596681-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="3964596681-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="3964596681-3">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">Opts</code>
│ │ │ +been initiated by this node. That is, the connection is set up via <code class="inline">setup/5</code>.</p></li><li><p><strong><code class="inline" id="hs_data_mf_setopts">mf_setopts</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="7235797529-1">(</span><span class="n">DistCtrl</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="7235797529-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="7235797529-2">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="7235797529-2">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">Opts</code>
│ │ │ +is a list of options to set on the connection.</p><p>This function is optional. Used when connection is up.</p></li><li><p><strong><code class="inline" id="hs_data_mf_getopts">mf_getopts</code></strong> - A fun with the following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="8011686450-1">(</span><span class="n">DistCtrl</span><span class="p">,</span><span class="w"> </span><span class="n">Opts</span><span class="p" data-group-id="8011686450-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8011686450-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">OptionValues</span><span class="p" data-group-id="8011686450-2">}</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="p" data-group-id="8011686450-3">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">Error</span><span class="p" data-group-id="8011686450-3">}</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller and <code class="inline">Opts</code>
│ │ │  is a list of options to read for the connection.</p><p>This function is optional. Used when connection is up.</p></li><li><p><strong><code class="inline" id="hs_data_f_handshake_complete">f_handshake_complete</code></strong> - A fun with the
│ │ │ -following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="5508047840-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p">,</span><span class="w"> </span><span class="n">DHandle</span><span class="p" data-group-id="5508047840-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">void</span><span class="p" data-group-id="5508047840-2">(</span><span class="p" data-group-id="5508047840-2">)</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller, <code class="inline">Node</code> is
│ │ │ +following signature:</p><pre><code class="makeup erlang" translate="no"><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="2518916178-1">(</span><span class="n">DistCtrlr</span><span class="p">,</span><span class="w"> </span><span class="n">Node</span><span class="p">,</span><span class="w"> </span><span class="n">DHandle</span><span class="p" data-group-id="2518916178-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">void</span><span class="p" data-group-id="2518916178-2">(</span><span class="p" data-group-id="2518916178-2">)</span></code></pre><p>where <code class="inline">DistCtrlr</code> is the identifier of the distribution controller, <code class="inline">Node</code> is
│ │ │  the node name of the node connected at the other end, and <code class="inline">DHandle</code> is a
│ │ │  distribution handle needed by a distribution controller process when calling
│ │ │  the following BIFs:</p><ul><li><a href="erlang.html#dist_ctrl_get_data/1"><code class="inline">erlang:dist_ctrl_get_data/1</code></a></li><li><a href="erlang.html#dist_ctrl_get_data_notification/1"><code class="inline">erlang:dist_ctrl_get_data_notification/1</code></a></li><li><a href="erlang.html#dist_ctrl_input_handler/2"><code class="inline">erlang:dist_ctrl_input_handler/2</code></a></li><li><a href="erlang.html#dist_ctrl_put_data/2"><code class="inline">erlang:dist_ctrl_put_data/2</code></a></li></ul><p>This function is called when the handshake has completed and the distribution
│ │ │  channel is up. The distribution controller can begin dispatching traffic over
│ │ │  the channel. This function is optional.</p><p>Only used during handshake phase.</p></li><li><p><strong><code class="inline" id="hs_data_add_flags">add_flags</code></strong> -
│ │ │  <a href="erl_dist_protocol.html#dflags">Distribution flags</a> to add to the connection.
│ │ │  Currently all (non obsolete) flags will automatically be enabled.</p><p>This flag field is optional.</p></li><li><p><strong><code class="inline" id="hs_data_reject_flags">reject_flags</code></strong> -
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/automaticyieldingofccode.html
│ │ │ @@ -209,17 +209,17 @@
│ │ │  they have to follow certain restrictions. The convention for making
│ │ │  this clear is to have a comment above the function that explains that
│ │ │  the function is transformed by YCF (see <code class="inline">maps_values_1_helper</code> in
│ │ │  <code class="inline">erl_map.c</code> for an example). If only the transformed version of the
│ │ │  function is used, the convention is to &quot;comment out&quot; the source for the
│ │ │  function by surrounding it with the following <code class="inline">#ifdef</code> (this way, one
│ │ │  will not get warnings about unused functions):</p><pre><code class="makeup erlang" translate="no"><span class="p">#</span><span class="ss">ifdef</span><span class="w"> </span><span class="n">INCLUDE_YCF_TRANSFORMED_ONLY_FUNCTIONS</span><span class="w">
│ │ │ -</span><span class="ss">void</span><span class="w"> </span><span class="nf">my_fun</span><span class="p" data-group-id="3541569781-1">(</span><span class="p" data-group-id="3541569781-1">)</span><span class="w"> </span><span class="p" data-group-id="3541569781-2">{</span><span class="w">
│ │ │ +</span><span class="ss">void</span><span class="w"> </span><span class="nf">my_fun</span><span class="p" data-group-id="1991939851-1">(</span><span class="p" data-group-id="1991939851-1">)</span><span class="w"> </span><span class="p" data-group-id="1991939851-2">{</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3541569781-2">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1991939851-2">}</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="ss">endif</span><span class="w"> </span><span class="o">/</span><span class="o">*</span><span class="w"> </span><span class="n">INCLUDE_YCF_TRANSFORMED_ONLY_FUNCTIONS</span><span class="w"> </span><span class="o">*</span><span class="o">/</span></code></pre><p>While editing the function one can define
│ │ │  <code class="inline">INCLUDE_YCF_TRANSFORMED_ONLY_FUNCTIONS</code> so that one can see errors
│ │ │  and warnings in the non-transformed source.</p><h3 id="where-to-place-ycf-transformed-functions" class="section-heading">
│ │ │    <a href="#where-to-place-ycf-transformed-functions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Where to Place YCF Transformed Functions</span>
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/beam_makeops.html
│ │ │ @@ -151,17 +151,17 @@
│ │ │  The loader translates generic instructions to specific instructions.
│ │ │  In general, for each generic instruction, there exists a family of
│ │ │  specific instructions.  The OTP 20 release has 389 specific
│ │ │  instructions.</p></li><li><p>The implementation of specific instructions for the traditional
│ │ │  BEAM interpreter. For the <a href="beamasm.html">BeamAsm JIT</a> introduced
│ │ │  in OTP 24, the implementation of instructions are defined in emitter
│ │ │  functions written in C++.</p></li></ul><p>Generic instructions have typed operands. Here are a few examples of
│ │ │ -operands for <code class="inline">move/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3822869814-1">{</span><span class="ss">move</span><span class="p">,</span><span class="p" data-group-id="3822869814-2">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">id</span><span class="p" data-group-id="3822869814-2">}</span><span class="p">,</span><span class="p" data-group-id="3822869814-3">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3822869814-3">}</span><span class="p" data-group-id="3822869814-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3822869814-4">{</span><span class="ss">move</span><span class="p">,</span><span class="p" data-group-id="3822869814-5">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3822869814-5">}</span><span class="p">,</span><span class="p" data-group-id="3822869814-6">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="3822869814-6">}</span><span class="p" data-group-id="3822869814-4">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3822869814-7">{</span><span class="ss">move</span><span class="p">,</span><span class="p" data-group-id="3822869814-8">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3822869814-8">}</span><span class="p">,</span><span class="p" data-group-id="3822869814-9">{</span><span class="ss">y</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3822869814-9">}</span><span class="p" data-group-id="3822869814-7">}</span><span class="p">.</span></code></pre><p>When those instructions are loaded, the loader rewrites them
│ │ │ +operands for <code class="inline">move/2</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5401159124-1">{</span><span class="ss">move</span><span class="p">,</span><span class="p" data-group-id="5401159124-2">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">id</span><span class="p" data-group-id="5401159124-2">}</span><span class="p">,</span><span class="p" data-group-id="5401159124-3">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5401159124-3">}</span><span class="p" data-group-id="5401159124-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5401159124-4">{</span><span class="ss">move</span><span class="p">,</span><span class="p" data-group-id="5401159124-5">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="5401159124-5">}</span><span class="p">,</span><span class="p" data-group-id="5401159124-6">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="5401159124-6">}</span><span class="p" data-group-id="5401159124-4">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5401159124-7">{</span><span class="ss">move</span><span class="p">,</span><span class="p" data-group-id="5401159124-8">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="5401159124-8">}</span><span class="p">,</span><span class="p" data-group-id="5401159124-9">{</span><span class="ss">y</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5401159124-9">}</span><span class="p" data-group-id="5401159124-7">}</span><span class="p">.</span></code></pre><p>When those instructions are loaded, the loader rewrites them
│ │ │  to specific instructions:</p><pre><code class="makeup erlang" translate="no"><span class="ss">move_cx</span><span class="w"> </span><span class="ss">id</span><span class="w"> </span><span class="mi">5</span><span class="w">
│ │ │  </span><span class="ss">move_xx</span><span class="w"> </span><span class="mi">3</span><span class="w"> </span><span class="mi">0</span><span class="w">
│ │ │  </span><span class="ss">move_xy</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="mi">1</span></code></pre><p>Corresponding to each generic instruction, there is a family of
│ │ │  specific instructions.  The types that an instance of a specific
│ │ │  instruction can handle are encoded in the instruction names.  For
│ │ │  example, <code class="inline">move_xy</code> takes an X register number as the first operand and
│ │ │  a Y register number as the second operand.  <code class="inline">move_cx</code> takes a tagged
│ │ │ @@ -185,17 +185,17 @@
│ │ │  </span><span class="ss">move</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="ss">x</span></code></pre><p>Each specific instructions is defined by following the name of the
│ │ │  instruction with the types for each operand.  An operand type is a
│ │ │  single letter.  For example, <code class="inline">x</code> means an X register, <code class="inline">y</code>
│ │ │  means a Y register, and <code class="inline">c</code> is a &quot;constant&quot; (a tagged term such as
│ │ │  an integer, an atom, or a literal).</p><p>Now let's look at the implementation of the <code class="inline">move</code> instruction.  There
│ │ │  are multiple files containing implementations of instructions in the
│ │ │  <code class="inline">erts/emulator/beam/emu</code> directory.  The <code class="inline">move</code> instruction is defined
│ │ │ -in <code class="inline">instrs.tab</code>.  It looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move</span><span class="p" data-group-id="6594286012-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="6594286012-1">)</span><span class="w"> </span><span class="p" data-group-id="6594286012-2">{</span><span class="w">
│ │ │ +in <code class="inline">instrs.tab</code>.  It looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move</span><span class="p" data-group-id="2242793824-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="2242793824-1">)</span><span class="w"> </span><span class="p" data-group-id="2242793824-2">{</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6594286012-2">}</span></code></pre><p>The implementation for an instruction largely follows the C syntax,
│ │ │ +</span><span class="p" data-group-id="2242793824-2">}</span></code></pre><p>The implementation for an instruction largely follows the C syntax,
│ │ │  except that the variables in the function head don't have any types.
│ │ │  The <code class="inline">$</code> before an identifier denotes a macro expansion.  Thus,
│ │ │  <code class="inline">$Src</code> will expand to the code to pick up the source operand for
│ │ │  the instruction and <code class="inline">$Dst</code> to the code for the destination register.</p><p>We will look at the code for each specific instruction in turn.  To
│ │ │  make the code easier to understand, let's first look at the memory
│ │ │  layout for the instruction <code class="inline">{move,{atom,id},{x,5}}</code>:</p><pre><code class="makeup erlang" translate="no"><span class="w">     </span><span class="o">+</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">+</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">+</span><span class="w">
│ │ │  </span><span class="n">I</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">|</span><span class="w">                 </span><span class="mi">40</span><span class="w"> </span><span class="p">|</span><span class="w">       </span><span class="p">&amp;&amp;</span><span class="ss">lb_move_cx</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │ @@ -204,61 +204,61 @@
│ │ │       </span><span class="o">+</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">+</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">+</span></code></pre><p>This example and all other examples in the document assumes a 64-bit
│ │ │  architecture, and furthermore that pointers to C code fit in 32 bits.</p><p><code class="inline">I</code> in the BEAM virtual machine is the instruction pointer.  When BEAM
│ │ │  executes an instruction, <code class="inline">I</code> points to the first word of the
│ │ │  instruction.</p><p><code class="inline">&amp;&amp;lb_move_cx</code> is the address to C code that implements <code class="inline">move_cx</code>.  It
│ │ │  is stored in the lower 32 bits of the word.  In the upper 32 bits is
│ │ │  the byte offset to the X register; the register number 5 has been
│ │ │  multiplied by the word size size 8.</p><p>In the next word the tagged atom <code class="inline">id</code> is stored.</p><p>With that background, we can look at the generated code for <code class="inline">move_cx</code>
│ │ │ -in <code class="inline">beam_hot.h</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="7717187555-1">(</span><span class="ss">move_cx</span><span class="p" data-group-id="7717187555-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7717187555-2">{</span><span class="w">
│ │ │ -  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="7717187555-3">(</span><span class="n">I</span><span class="p" data-group-id="7717187555-4">[</span><span class="mi">2</span><span class="p" data-group-id="7717187555-4">]</span><span class="p" data-group-id="7717187555-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="nf">xb</span><span class="p" data-group-id="7717187555-5">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="7717187555-6">(</span><span class="n">I</span><span class="p" data-group-id="7717187555-7">[</span><span class="mi">0</span><span class="p" data-group-id="7717187555-7">]</span><span class="p" data-group-id="7717187555-6">)</span><span class="p" data-group-id="7717187555-5">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="7717187555-8">[</span><span class="mi">1</span><span class="p" data-group-id="7717187555-8">]</span><span class="p">;</span><span class="w">
│ │ │ +in <code class="inline">beam_hot.h</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="7242833132-1">(</span><span class="ss">move_cx</span><span class="p" data-group-id="7242833132-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7242833132-2">{</span><span class="w">
│ │ │ +  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="7242833132-3">(</span><span class="n">I</span><span class="p" data-group-id="7242833132-4">[</span><span class="mi">2</span><span class="p" data-group-id="7242833132-4">]</span><span class="p" data-group-id="7242833132-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="nf">xb</span><span class="p" data-group-id="7242833132-5">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="7242833132-6">(</span><span class="n">I</span><span class="p" data-group-id="7242833132-7">[</span><span class="mi">0</span><span class="p" data-group-id="7242833132-7">]</span><span class="p" data-group-id="7242833132-6">)</span><span class="p" data-group-id="7242833132-5">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="7242833132-8">[</span><span class="mi">1</span><span class="p" data-group-id="7242833132-8">]</span><span class="p">;</span><span class="w">
│ │ │    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="7717187555-9">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="7717187555-10">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7717187555-10">)</span><span class="p" data-group-id="7717187555-9">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">GotoPF</span><span class="p" data-group-id="7717187555-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7717187555-11">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7717187555-2">}</span></code></pre><p>We will go through each line in turn.</p><ul><li><p><code class="inline">OpCase(move_cx):</code> defines a label for the instruction.  The
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="7242833132-9">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="7242833132-10">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7242833132-10">)</span><span class="p" data-group-id="7242833132-9">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">GotoPF</span><span class="p" data-group-id="7242833132-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7242833132-11">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7242833132-2">}</span></code></pre><p>We will go through each line in turn.</p><ul><li><p><code class="inline">OpCase(move_cx):</code> defines a label for the instruction.  The
│ │ │  <code class="inline">OpCase()</code> macro is defined in <code class="inline">beam_emu.c</code>.  It will expand this line
│ │ │  to <code class="inline">lb_move_cx:</code>.</p></li><li><p><code class="inline">BeamInstr next_pf = BeamCodeAddr(I[2]);</code> fetches the pointer to
│ │ │  code for the next instruction to be executed.  The <code class="inline">BeamCodeAddr()</code>
│ │ │  macro extracts the pointer from the lower 32 bits of the instruction
│ │ │  word.</p></li><li><p><code class="inline">xb(BeamExtraData(I[0])) = I[1];</code> is the expansion of <code class="inline">$Dst = $Src</code>.
│ │ │  <code class="inline">BeamExtraData()</code> is a macro that will extract the upper 32 bits from
│ │ │  the instruction word.  In this example, it will return 40 which is the
│ │ │  byte offset for X register 5.  The <code class="inline">xb()</code> macro will cast a byte
│ │ │  pointer to an <code class="inline">Eterm</code> pointer and dereference it.  The <code class="inline">I[1]</code> on
│ │ │  the right-hand side of the <code class="inline">=</code> fetches an Erlang term (the atom <code class="inline">id</code> in
│ │ │  this case).</p></li><li><p><code class="inline">I += 2</code> advances the instruction pointer to the next
│ │ │  instruction.</p></li><li><p>In a debug-compiled emulator, <code class="inline">ASSERT(VALID_INSTR(next_pf));</code> makes
│ │ │  sure that <code class="inline">next_pf</code> is a valid instruction (that is, that it points
│ │ │ -within the <code class="inline">process_main()</code> function in <code class="inline">beam_emu.c</code>).</p></li><li><p><code class="inline">GotoPF(next_pf);</code> transfers control to the next instruction.</p></li></ul><p>Now let's look at the implementation of <code class="inline">move_xx</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="7486027133-1">(</span><span class="ss">move_xx</span><span class="p" data-group-id="7486027133-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7486027133-2">{</span><span class="w">
│ │ │ -  </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">tmp_packed1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamExtraData</span><span class="p" data-group-id="7486027133-3">(</span><span class="n">I</span><span class="p" data-group-id="7486027133-4">[</span><span class="mi">0</span><span class="p" data-group-id="7486027133-4">]</span><span class="p" data-group-id="7486027133-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="7486027133-5">(</span><span class="n">I</span><span class="p" data-group-id="7486027133-6">[</span><span class="mi">1</span><span class="p" data-group-id="7486027133-6">]</span><span class="p" data-group-id="7486027133-5">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="nf">xb</span><span class="p" data-group-id="7486027133-7">(</span><span class="p" data-group-id="7486027133-8">(</span><span class="ss">tmp_packed1</span><span class="p">&gt;&gt;</span><span class="n">BEAM_TIGHT_SHIFT</span><span class="p" data-group-id="7486027133-8">)</span><span class="p" data-group-id="7486027133-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">xb</span><span class="p" data-group-id="7486027133-9">(</span><span class="ss">tmp_packed1</span><span class="err">&amp;</span><span class="n">BEAM_TIGHT_MASK</span><span class="p" data-group-id="7486027133-9">)</span><span class="p">;</span><span class="w">
│ │ │ +within the <code class="inline">process_main()</code> function in <code class="inline">beam_emu.c</code>).</p></li><li><p><code class="inline">GotoPF(next_pf);</code> transfers control to the next instruction.</p></li></ul><p>Now let's look at the implementation of <code class="inline">move_xx</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="0954700402-1">(</span><span class="ss">move_xx</span><span class="p" data-group-id="0954700402-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0954700402-2">{</span><span class="w">
│ │ │ +  </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">tmp_packed1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamExtraData</span><span class="p" data-group-id="0954700402-3">(</span><span class="n">I</span><span class="p" data-group-id="0954700402-4">[</span><span class="mi">0</span><span class="p" data-group-id="0954700402-4">]</span><span class="p" data-group-id="0954700402-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="0954700402-5">(</span><span class="n">I</span><span class="p" data-group-id="0954700402-6">[</span><span class="mi">1</span><span class="p" data-group-id="0954700402-6">]</span><span class="p" data-group-id="0954700402-5">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="nf">xb</span><span class="p" data-group-id="0954700402-7">(</span><span class="p" data-group-id="0954700402-8">(</span><span class="ss">tmp_packed1</span><span class="p">&gt;&gt;</span><span class="n">BEAM_TIGHT_SHIFT</span><span class="p" data-group-id="0954700402-8">)</span><span class="p" data-group-id="0954700402-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">xb</span><span class="p" data-group-id="0954700402-9">(</span><span class="ss">tmp_packed1</span><span class="err">&amp;</span><span class="n">BEAM_TIGHT_MASK</span><span class="p" data-group-id="0954700402-9">)</span><span class="p">;</span><span class="w">
│ │ │    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="7486027133-10">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="7486027133-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7486027133-11">)</span><span class="p" data-group-id="7486027133-10">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">GotoPF</span><span class="p" data-group-id="7486027133-12">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7486027133-12">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7486027133-2">}</span></code></pre><p>We will go through the lines that are new or have changed compared to
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="0954700402-10">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="0954700402-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="0954700402-11">)</span><span class="p" data-group-id="0954700402-10">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">GotoPF</span><span class="p" data-group-id="0954700402-12">(</span><span class="ss">next_pf</span><span class="p" data-group-id="0954700402-12">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0954700402-2">}</span></code></pre><p>We will go through the lines that are new or have changed compared to
│ │ │  <code class="inline">move_cx</code>.</p><ul><li><p><code class="inline">Eterm tmp_packed1 = BeamExtraData(I[0]);</code> picks up both X register
│ │ │  numbers packed into the upper 32 bits of the instruction word.</p></li><li><p><code class="inline">BeamInstr next_pf = BeamCodeAddr(I[1]);</code> pre-fetches the address of
│ │ │  the next instruction. Note that because both X registers operands fits
│ │ │  into the instruction word, the next instruction is in the very next
│ │ │  word.</p></li><li><p><code class="inline">xb((tmp_packed1&gt;&gt;BEAM_TIGHT_SHIFT)) = xb(tmp_packed1&amp;BEAM_TIGHT_MASK);</code>
│ │ │  copies the source to the destination.  (For a 64-bit architecture,
│ │ │  <code class="inline">BEAM_TIGHT_SHIFT</code> is 16 and <code class="inline">BEAM_TIGHT_MASK</code> is <code class="inline">0xFFFF</code>.)</p></li><li><p><code class="inline">I += 1;</code> advances the instruction pointer to the next instruction.</p></li></ul><p><code class="inline">move_xy</code> is almost identical to <code class="inline">move_xx</code>.  The only difference is
│ │ │  the use of the <code class="inline">yb()</code> macro instead of <code class="inline">xb()</code> to reference the
│ │ │ -destination register:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="0464369412-1">(</span><span class="ss">move_xy</span><span class="p" data-group-id="0464369412-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0464369412-2">{</span><span class="w">
│ │ │ -  </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">tmp_packed1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamExtraData</span><span class="p" data-group-id="0464369412-3">(</span><span class="n">I</span><span class="p" data-group-id="0464369412-4">[</span><span class="mi">0</span><span class="p" data-group-id="0464369412-4">]</span><span class="p" data-group-id="0464369412-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="0464369412-5">(</span><span class="n">I</span><span class="p" data-group-id="0464369412-6">[</span><span class="mi">1</span><span class="p" data-group-id="0464369412-6">]</span><span class="p" data-group-id="0464369412-5">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="nf">yb</span><span class="p" data-group-id="0464369412-7">(</span><span class="p" data-group-id="0464369412-8">(</span><span class="ss">tmp_packed1</span><span class="p">&gt;&gt;</span><span class="n">BEAM_TIGHT_SHIFT</span><span class="p" data-group-id="0464369412-8">)</span><span class="p" data-group-id="0464369412-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">xb</span><span class="p" data-group-id="0464369412-9">(</span><span class="ss">tmp_packed1</span><span class="err">&amp;</span><span class="n">BEAM_TIGHT_MASK</span><span class="p" data-group-id="0464369412-9">)</span><span class="p">;</span><span class="w">
│ │ │ +destination register:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="6884228442-1">(</span><span class="ss">move_xy</span><span class="p" data-group-id="6884228442-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6884228442-2">{</span><span class="w">
│ │ │ +  </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">tmp_packed1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamExtraData</span><span class="p" data-group-id="6884228442-3">(</span><span class="n">I</span><span class="p" data-group-id="6884228442-4">[</span><span class="mi">0</span><span class="p" data-group-id="6884228442-4">]</span><span class="p" data-group-id="6884228442-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="6884228442-5">(</span><span class="n">I</span><span class="p" data-group-id="6884228442-6">[</span><span class="mi">1</span><span class="p" data-group-id="6884228442-6">]</span><span class="p" data-group-id="6884228442-5">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="nf">yb</span><span class="p" data-group-id="6884228442-7">(</span><span class="p" data-group-id="6884228442-8">(</span><span class="ss">tmp_packed1</span><span class="p">&gt;&gt;</span><span class="n">BEAM_TIGHT_SHIFT</span><span class="p" data-group-id="6884228442-8">)</span><span class="p" data-group-id="6884228442-7">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">xb</span><span class="p" data-group-id="6884228442-9">(</span><span class="ss">tmp_packed1</span><span class="err">&amp;</span><span class="n">BEAM_TIGHT_MASK</span><span class="p" data-group-id="6884228442-9">)</span><span class="p">;</span><span class="w">
│ │ │    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="0464369412-10">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="0464369412-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="0464369412-11">)</span><span class="p" data-group-id="0464369412-10">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">GotoPF</span><span class="p" data-group-id="0464369412-12">(</span><span class="ss">next_pf</span><span class="p" data-group-id="0464369412-12">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0464369412-2">}</span></code></pre><h3 id="transformation-rules" class="section-heading">
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="6884228442-10">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="6884228442-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="6884228442-11">)</span><span class="p" data-group-id="6884228442-10">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">GotoPF</span><span class="p" data-group-id="6884228442-12">(</span><span class="ss">next_pf</span><span class="p" data-group-id="6884228442-12">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6884228442-2">}</span></code></pre><h3 id="transformation-rules" class="section-heading">
│ │ │    <a href="#transformation-rules" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Transformation rules</span>
│ │ │  </h3>
│ │ │  <p>Next let's look at how we can do some optimizations using transformation
│ │ │  rules.  For simple instructions such as <code class="inline">move/2</code>, the instruction dispatch
│ │ │ @@ -271,21 +271,21 @@
│ │ │  with an uppercase letter just as in Erlang.  A pattern variable may be
│ │ │  followed <code class="inline">=</code> and one or more type letters to constrain the match to
│ │ │  one of those types.  The variables that are bound on the left-hand side can
│ │ │  be used on the right-hand side.</p><p>We will also need to define a specific instruction and an implementation:</p><pre><code class="makeup erlang" translate="no"><span class="p">#</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="ss">ops</span><span class="p">.</span><span class="ss">tab</span><span class="w">
│ │ │  </span><span class="ss">move2</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">y</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="ss">instrs</span><span class="p">.</span><span class="ss">tab</span><span class="w">
│ │ │ -</span><span class="nf">move2</span><span class="p" data-group-id="8550787656-1">(</span><span class="n">S1</span><span class="p">,</span><span class="w"> </span><span class="n">D1</span><span class="p">,</span><span class="w"> </span><span class="n">S2</span><span class="p">,</span><span class="w"> </span><span class="n">D2</span><span class="p" data-group-id="8550787656-1">)</span><span class="w"> </span><span class="p" data-group-id="8550787656-2">{</span><span class="w">
│ │ │ +</span><span class="nf">move2</span><span class="p" data-group-id="4074639362-1">(</span><span class="n">S1</span><span class="p">,</span><span class="w"> </span><span class="n">D1</span><span class="p">,</span><span class="w"> </span><span class="n">S2</span><span class="p">,</span><span class="w"> </span><span class="n">D2</span><span class="p" data-group-id="4074639362-1">)</span><span class="w"> </span><span class="p" data-group-id="4074639362-2">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="n">V1</span><span class="p">,</span><span class="w"> </span><span class="n">V2</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">V1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">V2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="mi">1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">V1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="mi">2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">V2</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8550787656-2">}</span></code></pre><p>When the loader has found a match and replaced the matched instructions,
│ │ │ +</span><span class="p" data-group-id="4074639362-2">}</span></code></pre><p>When the loader has found a match and replaced the matched instructions,
│ │ │  it will match the new instructions against the transformation rules.
│ │ │  Because of that, we can define the rule for a <code class="inline">move3/6</code> instruction
│ │ │  as follows:</p><pre><code class="makeup erlang" translate="no"><span class="ss">move2</span><span class="w"> </span><span class="n">X1</span><span class="o">=</span><span class="ss">x</span><span class="w"> </span><span class="n">Y1</span><span class="o">=</span><span class="ss">y</span><span class="w"> </span><span class="n">X2</span><span class="o">=</span><span class="ss">x</span><span class="w"> </span><span class="n">Y2</span><span class="o">=</span><span class="ss">y</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">move</span><span class="w"> </span><span class="n">X3</span><span class="o">=</span><span class="ss">x</span><span class="w"> </span><span class="n">Y3</span><span class="o">=</span><span class="ss">y</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │        </span><span class="ss">move3</span><span class="w"> </span><span class="n">X1</span><span class="w"> </span><span class="n">Y1</span><span class="w"> </span><span class="n">X2</span><span class="w"> </span><span class="n">Y2</span><span class="w"> </span><span class="n">X3</span><span class="w"> </span><span class="n">Y3</span></code></pre><p>(For readability, a long transformation line can be broken after <code class="inline">|</code>
│ │ │  and <code class="inline">=&gt;</code> operators.)</p><p>It would also be possible to define it like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">move</span><span class="w"> </span><span class="n">X1</span><span class="o">=</span><span class="ss">x</span><span class="w"> </span><span class="n">Y1</span><span class="o">=</span><span class="ss">y</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">move</span><span class="w"> </span><span class="n">X2</span><span class="o">=</span><span class="ss">x</span><span class="w"> </span><span class="n">Y2</span><span class="o">=</span><span class="ss">y</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">move</span><span class="w"> </span><span class="n">X3</span><span class="o">=</span><span class="ss">x</span><span class="w"> </span><span class="n">Y3</span><span class="o">=</span><span class="ss">y</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │       </span><span class="ss">move3</span><span class="w"> </span><span class="n">X1</span><span class="w"> </span><span class="n">Y1</span><span class="w"> </span><span class="n">X2</span><span class="w"> </span><span class="n">Y2</span><span class="w"> </span><span class="n">X3</span><span class="w"> </span><span class="n">Y3</span></code></pre><p>but in that case it must be defined before the rule for <code class="inline">move2/4</code>
│ │ │  because the first matching rule will be applied.</p><p>One must be careful not to create infinite loops.  For example, if we
│ │ │ @@ -433,29 +433,29 @@
│ │ │  </span><span class="ss">i_bs_get_integer_32</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">f</span><span class="o">?</span><span class="w"> </span><span class="ss">x</span><span class="w">
│ │ │  </span><span class="c1">%endif</span></code></pre><p>The specific instruction <code class="inline">i_bs_get_integer_32</code> will only be defined
│ │ │  on a 64-bit machine.</p><p>The condition can be inverted by using <code class="inline">%unless</code> instead of <code class="inline">%if</code>:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%unless NO_FPE_SIGNALS</span><span class="w">
│ │ │  </span><span class="ss">fcheckerror</span><span class="w"> </span><span class="ss">p</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">i_fcheckerror</span><span class="w">
│ │ │  </span><span class="ss">i_fcheckerror</span><span class="w">
│ │ │  </span><span class="ss">fclearerror</span><span class="w">
│ │ │  </span><span class="c1">%endif</span></code></pre><p>It is also possible to add an <code class="inline">%else</code> clause:</p><pre><code class="makeup erlang" translate="no"><span class="c1">%if ARCH_64</span><span class="w">
│ │ │ -</span><span class="n">BS_SAFE_MUL</span><span class="p" data-group-id="9421167422-1">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="9421167422-1">)</span><span class="w"> </span><span class="p" data-group-id="9421167422-2">{</span><span class="w">
│ │ │ -    </span><span class="n">Uint64</span><span class="w"> </span><span class="ss">res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9421167422-3">(</span><span class="sc">$A</span><span class="p" data-group-id="9421167422-3">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="9421167422-4">(</span><span class="sc">$B</span><span class="p" data-group-id="9421167422-4">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="9421167422-5">(</span><span class="ss">res</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="sc">$B</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="sc">$A</span><span class="p" data-group-id="9421167422-5">)</span><span class="w"> </span><span class="p" data-group-id="9421167422-6">{</span><span class="w">
│ │ │ +</span><span class="n">BS_SAFE_MUL</span><span class="p" data-group-id="3193569181-1">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="3193569181-1">)</span><span class="w"> </span><span class="p" data-group-id="3193569181-2">{</span><span class="w">
│ │ │ +    </span><span class="n">Uint64</span><span class="w"> </span><span class="ss">res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3193569181-3">(</span><span class="sc">$A</span><span class="p" data-group-id="3193569181-3">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="3193569181-4">(</span><span class="sc">$B</span><span class="p" data-group-id="3193569181-4">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="3193569181-5">(</span><span class="ss">res</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="sc">$B</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="sc">$A</span><span class="p" data-group-id="3193569181-5">)</span><span class="w"> </span><span class="p" data-group-id="3193569181-6">{</span><span class="w">
│ │ │          </span><span class="sc">$F</span><span class="ss">ail</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9421167422-6">}</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3193569181-6">}</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">res</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9421167422-2">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3193569181-2">}</span><span class="w">
│ │ │  </span><span class="c1">%else</span><span class="w">
│ │ │ -</span><span class="n">BS_SAFE_MUL</span><span class="p" data-group-id="9421167422-7">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="9421167422-7">)</span><span class="w"> </span><span class="p" data-group-id="9421167422-8">{</span><span class="w">
│ │ │ -    </span><span class="n">Uint64</span><span class="w"> </span><span class="ss">res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9421167422-9">(</span><span class="n">Uint64</span><span class="p" data-group-id="9421167422-9">)</span><span class="p" data-group-id="9421167422-10">(</span><span class="sc">$A</span><span class="p" data-group-id="9421167422-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="9421167422-11">(</span><span class="n">Uint64</span><span class="p" data-group-id="9421167422-11">)</span><span class="p" data-group-id="9421167422-12">(</span><span class="sc">$B</span><span class="p" data-group-id="9421167422-12">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="9421167422-13">(</span><span class="p" data-group-id="9421167422-14">(</span><span class="ss">res</span><span class="w"> </span><span class="p">&gt;&gt;</span><span class="w"> </span><span class="p" data-group-id="9421167422-15">(</span><span class="mi">8</span><span class="o">*</span><span class="nf">sizeof</span><span class="p" data-group-id="9421167422-16">(</span><span class="n">Uint</span><span class="p" data-group-id="9421167422-16">)</span><span class="p" data-group-id="9421167422-15">)</span><span class="p" data-group-id="9421167422-14">)</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="9421167422-13">)</span><span class="w"> </span><span class="p" data-group-id="9421167422-17">{</span><span class="w">
│ │ │ +</span><span class="n">BS_SAFE_MUL</span><span class="p" data-group-id="3193569181-7">(</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="3193569181-7">)</span><span class="w"> </span><span class="p" data-group-id="3193569181-8">{</span><span class="w">
│ │ │ +    </span><span class="n">Uint64</span><span class="w"> </span><span class="ss">res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3193569181-9">(</span><span class="n">Uint64</span><span class="p" data-group-id="3193569181-9">)</span><span class="p" data-group-id="3193569181-10">(</span><span class="sc">$A</span><span class="p" data-group-id="3193569181-10">)</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="3193569181-11">(</span><span class="n">Uint64</span><span class="p" data-group-id="3193569181-11">)</span><span class="p" data-group-id="3193569181-12">(</span><span class="sc">$B</span><span class="p" data-group-id="3193569181-12">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="3193569181-13">(</span><span class="p" data-group-id="3193569181-14">(</span><span class="ss">res</span><span class="w"> </span><span class="p">&gt;&gt;</span><span class="w"> </span><span class="p" data-group-id="3193569181-15">(</span><span class="mi">8</span><span class="o">*</span><span class="nf">sizeof</span><span class="p" data-group-id="3193569181-16">(</span><span class="n">Uint</span><span class="p" data-group-id="3193569181-16">)</span><span class="p" data-group-id="3193569181-15">)</span><span class="p" data-group-id="3193569181-14">)</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3193569181-13">)</span><span class="w"> </span><span class="p" data-group-id="3193569181-17">{</span><span class="w">
│ │ │          </span><span class="sc">$F</span><span class="ss">ail</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="9421167422-17">}</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3193569181-17">}</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">res</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9421167422-8">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3193569181-8">}</span><span class="w">
│ │ │  </span><span class="c1">%endif</span></code></pre><h4>Symbols that are defined in directives</h4><p>The following symbols are always defined.</p><ul><li><code class="inline">ARCH_64</code> - is 1 for a 64-bit machine, and 0 otherwise.</li><li><code class="inline">ARCH_32</code> - is 1 for 32-bit machine, and 0 otherwise.</li></ul><p>The <code class="inline">Makefile</code> for building the emulator currently defines the
│ │ │  following symbols by using the <code class="inline">-D</code> option on the command line for
│ │ │  <strong>beam_makeops</strong>.</p><ul><li><code class="inline">USE_VM_PROBES</code> - 1 if the runtime system is compiled to use VM
│ │ │  probes (support for dtrace or systemtap), 0 otherwise.</li></ul><h3 id="defining-external-generic-instructions" class="section-heading">
│ │ │    <a href="#defining-external-generic-instructions" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -676,15 +676,15 @@
│ │ │  match both source and destination registers.  As an operand in a specific
│ │ │  instruction, it must only be used for a destination register.)</p></li><li><p><code class="inline">o</code> - Overflow.  An untagged integer that does not fit in a machine word.</p></li></ul><h4>Predicates</h4><p>If the constraints described so far is not enough, additional
│ │ │  constraints can be implemented in C and be called as a guard function
│ │ │  on the left-hand side of the transformation.  If the guard function returns
│ │ │  a non-zero value, the matching of the rule will continue, otherwise
│ │ │  the match will fail.  Such guard functions are hereafter called
│ │ │  <em>predicates</em>.</p><p>The most commonly used guard constraints is <code class="inline">equal()</code>. It can be used
│ │ │ -to remove a redundant <code class="inline">move</code> instructio like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">move</span><span class="w"> </span><span class="n">R1</span><span class="w"> </span><span class="n">R2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">equal</span><span class="p" data-group-id="3192223217-1">(</span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p" data-group-id="3192223217-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p">_</span></code></pre><p>or remove a redundant <code class="inline">is_eq_exact</code> instruction like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">is_eq_exact</span><span class="w"> </span><span class="n">Lbl</span><span class="w"> </span><span class="n">Src1</span><span class="w"> </span><span class="n">Src2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">equal</span><span class="p" data-group-id="2315886105-1">(</span><span class="n">Src1</span><span class="p">,</span><span class="w"> </span><span class="n">Src2</span><span class="p" data-group-id="2315886105-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p">_</span></code></pre><p>At the time of writing, all predicates are defined in files named
│ │ │ +to remove a redundant <code class="inline">move</code> instructio like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">move</span><span class="w"> </span><span class="n">R1</span><span class="w"> </span><span class="n">R2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">equal</span><span class="p" data-group-id="7016364132-1">(</span><span class="n">R1</span><span class="p">,</span><span class="w"> </span><span class="n">R2</span><span class="p" data-group-id="7016364132-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p">_</span></code></pre><p>or remove a redundant <code class="inline">is_eq_exact</code> instruction like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">is_eq_exact</span><span class="w"> </span><span class="n">Lbl</span><span class="w"> </span><span class="n">Src1</span><span class="w"> </span><span class="n">Src2</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="nf">equal</span><span class="p" data-group-id="9799706572-1">(</span><span class="n">Src1</span><span class="p">,</span><span class="w"> </span><span class="n">Src2</span><span class="p" data-group-id="9799706572-1">)</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p">_</span></code></pre><p>At the time of writing, all predicates are defined in files named
│ │ │  <code class="inline">predicates.tab</code> in several directories.  In <code class="inline">predicates.tab</code> directly
│ │ │  in <code class="inline">$ERL_TOP/erts/emulator/beam</code>, predicates that are used by both the
│ │ │  traditinal emulator and the JIT implementations are contained.
│ │ │  Predicates only used by the emulator can be found in
│ │ │  <code class="inline">emu/predicates.tab</code>.</p><h3 id="a-very-brief-note-on-implementation-of-predicates" class="section-heading">
│ │ │    <a href="#a-very-brief-note-on-implementation-of-predicates" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -692,41 +692,41 @@
│ │ │    <span class="text">A very brief note on implementation of predicates</span>
│ │ │  </h3>
│ │ │  <p>It is outside the scope for this document to describe in detail how
│ │ │  predicates are implemented because it requires knowledge of the
│ │ │  internal loader data structures, but here is quick look at the
│ │ │  implementation of a simple predicate called <code class="inline">literal_is_map()</code>.</p><p>Here is first an example how it is used:</p><p>   is<em>map Fail Lit=q | literal_is_map(Lit) =&gt; </em></p><p>If the <code class="inline">Lit</code> operand is a literal, then the <code class="inline">literal_is_map()</code>
│ │ │  predicate is called to determine whether it is a map literal.
│ │ │ -If it is, the instruction is not needed and can be removed.</p><p><code class="inline">literal_is_map()</code> is implemented like this (in <code class="inline">emu/predicates.tab</code>):</p><pre><code class="makeup erlang" translate="no"><span class="ss">pred</span><span class="p">.</span><span class="nf">literal_is_map</span><span class="p" data-group-id="1201187378-1">(</span><span class="n">Lit</span><span class="p" data-group-id="1201187378-1">)</span><span class="w"> </span><span class="p" data-group-id="1201187378-2">{</span><span class="w">
│ │ │ +If it is, the instruction is not needed and can be removed.</p><p><code class="inline">literal_is_map()</code> is implemented like this (in <code class="inline">emu/predicates.tab</code>):</p><pre><code class="makeup erlang" translate="no"><span class="ss">pred</span><span class="p">.</span><span class="nf">literal_is_map</span><span class="p" data-group-id="3353096392-1">(</span><span class="n">Lit</span><span class="p" data-group-id="3353096392-1">)</span><span class="w"> </span><span class="p" data-group-id="3353096392-2">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">term</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="1201187378-3">(</span><span class="n">Lit</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_q</span><span class="p" data-group-id="1201187378-3">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">term</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">beamfile_get_literal</span><span class="p" data-group-id="1201187378-4">(</span><span class="err">&amp;</span><span class="n">S</span><span class="p">-&gt;</span><span class="ss">beam</span><span class="p">,</span><span class="w"> </span><span class="n">Lit</span><span class="p">.</span><span class="ss">val</span><span class="p" data-group-id="1201187378-4">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">return</span><span class="w"> </span><span class="nf">is_map</span><span class="p" data-group-id="1201187378-5">(</span><span class="ss">term</span><span class="p" data-group-id="1201187378-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1201187378-2">}</span></code></pre><p>The <code class="inline">pred.</code> prefix tells <strong>beam_makeops</strong> that this function is a
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="3353096392-3">(</span><span class="n">Lit</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_q</span><span class="p" data-group-id="3353096392-3">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">term</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">beamfile_get_literal</span><span class="p" data-group-id="3353096392-4">(</span><span class="err">&amp;</span><span class="n">S</span><span class="p">-&gt;</span><span class="ss">beam</span><span class="p">,</span><span class="w"> </span><span class="n">Lit</span><span class="p">.</span><span class="ss">val</span><span class="p" data-group-id="3353096392-4">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">return</span><span class="w"> </span><span class="nf">is_map</span><span class="p" data-group-id="3353096392-5">(</span><span class="ss">term</span><span class="p" data-group-id="3353096392-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3353096392-2">}</span></code></pre><p>The <code class="inline">pred.</code> prefix tells <strong>beam_makeops</strong> that this function is a
│ │ │  predicate.  Without the prefix, it would have been interpreted as the
│ │ │  implementation of an instruction (described in <strong>Defining the
│ │ │  implementation</strong>).</p><p>Predicate functions have a magic variabled called <code class="inline">S</code>, which is a
│ │ │  pointer to a state struct. In the example,
│ │ │  <code class="inline">beamfile_get_literal(&amp;S-&gt;beam, Lit.val);</code> is used to retrieve the actual term
│ │ │  for the literal.</p><p>At the time of writing, the expanded C code generated by
│ │ │ -<strong>beam_makeops</strong> looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">static</span><span class="w"> </span><span class="ss">int</span><span class="w"> </span><span class="nf">literal_is_map</span><span class="p" data-group-id="4579458298-1">(</span><span class="n">LoaderState</span><span class="o">*</span><span class="w"> </span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="n">BeamOpArg</span><span class="w"> </span><span class="n">Lit</span><span class="p" data-group-id="4579458298-1">)</span><span class="w"> </span><span class="p" data-group-id="4579458298-2">{</span><span class="w">
│ │ │ +<strong>beam_makeops</strong> looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">static</span><span class="w"> </span><span class="ss">int</span><span class="w"> </span><span class="nf">literal_is_map</span><span class="p" data-group-id="3107375491-1">(</span><span class="n">LoaderState</span><span class="o">*</span><span class="w"> </span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="n">BeamOpArg</span><span class="w"> </span><span class="n">Lit</span><span class="p" data-group-id="3107375491-1">)</span><span class="w"> </span><span class="p" data-group-id="3107375491-2">{</span><span class="w">
│ │ │    </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">term</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="4579458298-3">(</span><span class="n">Lit</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_q</span><span class="p" data-group-id="4579458298-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="ss">term</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p">-&gt;</span><span class="ss">literals</span><span class="p" data-group-id="4579458298-4">[</span><span class="n">Lit</span><span class="p">.</span><span class="ss">val</span><span class="p" data-group-id="4579458298-4">]</span><span class="p">.</span><span class="ss">term</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="ss">return</span><span class="w"> </span><span class="nf">is_map</span><span class="p" data-group-id="4579458298-5">(</span><span class="ss">term</span><span class="p" data-group-id="4579458298-5">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4579458298-2">}</span></code></pre><h4>Handling instructions with variable number of operands</h4><p>Some instructions, such as <code class="inline">select_val/3</code>, essentially has a variable
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="3107375491-3">(</span><span class="n">Lit</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_q</span><span class="p" data-group-id="3107375491-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="ss">term</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">S</span><span class="p">-&gt;</span><span class="ss">literals</span><span class="p" data-group-id="3107375491-4">[</span><span class="n">Lit</span><span class="p">.</span><span class="ss">val</span><span class="p" data-group-id="3107375491-4">]</span><span class="p">.</span><span class="ss">term</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="ss">return</span><span class="w"> </span><span class="nf">is_map</span><span class="p" data-group-id="3107375491-5">(</span><span class="ss">term</span><span class="p" data-group-id="3107375491-5">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3107375491-2">}</span></code></pre><h4>Handling instructions with variable number of operands</h4><p>Some instructions, such as <code class="inline">select_val/3</code>, essentially has a variable
│ │ │  number of operands.  Such instructions have a <code class="inline">{list,[...]}</code> operand
│ │ │ -as their last operand in the BEAM assembly code.  For example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0937542988-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="0937542988-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="0937542988-2">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0937542988-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="0937542988-3">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="0937542988-4">{</span><span class="ss">list</span><span class="p">,</span><span class="p" data-group-id="0937542988-5">[</span><span class="p" data-group-id="0937542988-6">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="0937542988-6">}</span><span class="p">,</span><span class="p" data-group-id="0937542988-7">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="0937542988-7">}</span><span class="p">,</span><span class="p" data-group-id="0937542988-8">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="0937542988-8">}</span><span class="p">,</span><span class="p" data-group-id="0937542988-9">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="0937542988-9">}</span><span class="p" data-group-id="0937542988-5">]</span><span class="p" data-group-id="0937542988-4">}</span><span class="p" data-group-id="0937542988-1">}</span><span class="p">.</span></code></pre><p>The loader will convert a <code class="inline">{list,[...]}</code> operand to an <code class="inline">u</code> operand whose
│ │ │ +as their last operand in the BEAM assembly code.  For example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6027248188-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="6027248188-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="6027248188-2">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6027248188-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="6027248188-3">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6027248188-4">{</span><span class="ss">list</span><span class="p">,</span><span class="p" data-group-id="6027248188-5">[</span><span class="p" data-group-id="6027248188-6">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6027248188-6">}</span><span class="p">,</span><span class="p" data-group-id="6027248188-7">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6027248188-7">}</span><span class="p">,</span><span class="p" data-group-id="6027248188-8">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="6027248188-8">}</span><span class="p">,</span><span class="p" data-group-id="6027248188-9">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6027248188-9">}</span><span class="p" data-group-id="6027248188-5">]</span><span class="p" data-group-id="6027248188-4">}</span><span class="p" data-group-id="6027248188-1">}</span><span class="p">.</span></code></pre><p>The loader will convert a <code class="inline">{list,[...]}</code> operand to an <code class="inline">u</code> operand whose
│ │ │  value is the number of elements in the list, followed by each element in
│ │ │  the list.  The instruction above would be translated to the following
│ │ │ -generic instruction:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5619290930-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="5619290930-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="5619290930-2">}</span><span class="p">,</span><span class="p" data-group-id="5619290930-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5619290930-3">}</span><span class="p">,</span><span class="p" data-group-id="5619290930-4">{</span><span class="ss">u</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5619290930-4">}</span><span class="p">,</span><span class="p" data-group-id="5619290930-5">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5619290930-5">}</span><span class="p">,</span><span class="p" data-group-id="5619290930-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5619290930-6">}</span><span class="p">,</span><span class="p" data-group-id="5619290930-7">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="5619290930-7">}</span><span class="p">,</span><span class="p" data-group-id="5619290930-8">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5619290930-8">}</span><span class="p" data-group-id="5619290930-1">}</span></code></pre><p>To match a variable number of arguments we need to use the special
│ │ │ +generic instruction:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2571073559-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="2571073559-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="2571073559-2">}</span><span class="p">,</span><span class="p" data-group-id="2571073559-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2571073559-3">}</span><span class="p">,</span><span class="p" data-group-id="2571073559-4">{</span><span class="ss">u</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2571073559-4">}</span><span class="p">,</span><span class="p" data-group-id="2571073559-5">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="2571073559-5">}</span><span class="p">,</span><span class="p" data-group-id="2571073559-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2571073559-6">}</span><span class="p">,</span><span class="p" data-group-id="2571073559-7">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="2571073559-7">}</span><span class="p">,</span><span class="p" data-group-id="2571073559-8">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2571073559-8">}</span><span class="p" data-group-id="2571073559-1">}</span></code></pre><p>To match a variable number of arguments we need to use the special
│ │ │  operand type <code class="inline">*</code> like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">select_val</span><span class="w"> </span><span class="n">Src</span><span class="o">=</span><span class="ss">aiq</span><span class="w"> </span><span class="n">Fail</span><span class="o">=</span><span class="ss">f</span><span class="w"> </span><span class="n">Size</span><span class="o">=</span><span class="ss">u</span><span class="w"> </span><span class="n">List</span><span class="o">=</span><span class="o">*</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │      </span><span class="ss">i_const_select_val</span><span class="w"> </span><span class="n">Src</span><span class="w"> </span><span class="n">Fail</span><span class="w"> </span><span class="n">Size</span><span class="w"> </span><span class="n">List</span></code></pre><p>This transformation renames a <code class="inline">select_val/3</code> instruction
│ │ │  with a constant source operand to <code class="inline">i_const_select_val/3</code>.</p><h4>Constructing new instructions on the right-hand side</h4><p>The most common operand on the right-hand side is a variable that was
│ │ │  bound while matching the pattern on the left-hand side.  For example:</p><pre><code class="makeup erlang" translate="no"><span class="ss">trim</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="n">Remaining</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">i_trim</span><span class="w"> </span><span class="n">N</span></code></pre><p>An operand can also be a type letter to construct an operand of that
│ │ │  type.  Each type has a default value.  For example, the type <code class="inline">x</code> has
│ │ │  the default value 1023, which is the highest X register.  That makes
│ │ │  <code class="inline">x</code> on the right-hand side a convenient shortcut for a temporary X
│ │ │ @@ -746,53 +746,53 @@
│ │ │  transformation rule.</p><ul><li><p><code class="inline">u</code> - Construct an untagged integer.  The default value is 0.</p></li><li><p><code class="inline">x</code> - X register.  The default value is 1023.  That makes <code class="inline">x</code> convenient to
│ │ │  use as a temporary X register.</p></li><li><p><code class="inline">y</code> - Y register.  The default value is 0.</p></li><li><p><code class="inline">l</code> - Floating point register number.  The default value is 0.</p></li><li><p><code class="inline">i</code> - Tagged literal integer.  The default value is 0.</p></li><li><p><code class="inline">a</code> - Tagged atom.  The default value is the empty atom (<code class="inline">am_Empty</code>).</p></li><li><p><code class="inline">p</code> - Zero failure label.</p></li><li><p><code class="inline">n</code> - NIL (<code class="inline">[]</code>, the empty list).</p></li></ul><h4>Function call on the right-hand side</h4><p>Transformations that are not possible to describe with the rule
│ │ │  language as described here can be implemented as a generator function
│ │ │  in C and called from the right-hand side of a transformation.  The left-hand
│ │ │  side of the transformation will perform the match and bind operands to
│ │ │  variables.  The variables can then be passed to a generator function
│ │ │  on the right-hand side.  For example:</p><pre><code class="makeup erlang" translate="no"><span class="ss">bif2</span><span class="w"> </span><span class="n">Fail</span><span class="o">=</span><span class="ss">j</span><span class="w"> </span><span class="ss">u</span><span class="sc">$b</span><span class="nc">if</span><span class="p">:</span><span class="nc">erlang</span><span class="p">:</span><span class="nb">element</span><span class="p">/</span><span class="mi">2</span><span class="w"> </span><span class="n">Index</span><span class="o">=</span><span class="ss">s</span><span class="w"> </span><span class="n">Tuple</span><span class="o">=</span><span class="ss">xy</span><span class="w"> </span><span class="n">Dst</span><span class="o">=</span><span class="ss">d</span><span class="w"> </span><span class="p">=&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">element</span><span class="p" data-group-id="9101658713-1">(</span><span class="n">Jump</span><span class="p">,</span><span class="w"> </span><span class="n">Index</span><span class="p">,</span><span class="w"> </span><span class="n">Tuple</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="9101658713-1">)</span></code></pre><p>This transformation rule matches a call to the BIF <a href="erlang.html#element/2"><code class="inline">element/2</code></a>.
│ │ │ +    </span><span class="nf">element</span><span class="p" data-group-id="7784628491-1">(</span><span class="n">Jump</span><span class="p">,</span><span class="w"> </span><span class="n">Index</span><span class="p">,</span><span class="w"> </span><span class="n">Tuple</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="7784628491-1">)</span></code></pre><p>This transformation rule matches a call to the BIF <a href="erlang.html#element/2"><code class="inline">element/2</code></a>.
│ │ │  The operands will be captured and the generator function <code class="inline">element()</code> will
│ │ │  be called.</p><p>The <code class="inline">element()</code> generator will produce one of two instructions
│ │ │  depending on <code class="inline">Index</code>.  If <code class="inline">Index</code> is an integer in the range from 1 up
│ │ │  to the maximum tuple size, the instruction <code class="inline">i_fast_element/2</code> will be
│ │ │  produced, otherwise the instruction <code class="inline">i_element/4</code> will be produced.
│ │ │  The corresponding specific instructions are:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_fast_element</span><span class="w"> </span><span class="ss">xy</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="n">I</span><span class="w"> </span><span class="ss">d</span><span class="w">
│ │ │  </span><span class="ss">i_element</span><span class="w"> </span><span class="ss">xy</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">d</span></code></pre><p>The <code class="inline">i_fast_element/2</code> instruction is faster because the tuple is
│ │ │  already an untagged integer.  It also knows that the index is at least
│ │ │  1, so it does not have to test for that.  The <code class="inline">i_element/4</code>
│ │ │  instruction will have to fetch the index from a register, test that it
│ │ │  is an integer, and untag the integer.</p><p>At the time of writing, all generators functions were defined in files
│ │ │  named <code class="inline">generators.tab</code> in several directories (in the same directories
│ │ │  as the <code class="inline">predicates.tab</code> files).</p><p>It is outside the scope of this document to describe in detail how
│ │ │  generator functions are written, but here is the implementation of
│ │ │ -<code class="inline">element()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">gen</span><span class="p">.</span><span class="nf">element</span><span class="p" data-group-id="2251046389-1">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Index</span><span class="p">,</span><span class="w"> </span><span class="n">Tuple</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="2251046389-1">)</span><span class="w"> </span><span class="p" data-group-id="2251046389-2">{</span><span class="w">
│ │ │ +<code class="inline">element()</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">gen</span><span class="p">.</span><span class="nf">element</span><span class="p" data-group-id="8322604306-1">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Index</span><span class="p">,</span><span class="w"> </span><span class="n">Tuple</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="8322604306-1">)</span><span class="w"> </span><span class="p" data-group-id="8322604306-2">{</span><span class="w">
│ │ │      </span><span class="n">BeamOp</span><span class="o">*</span><span class="w"> </span><span class="ss">op</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="sc">$N</span><span class="nf">ewBeamOp</span><span class="p" data-group-id="2251046389-3">(</span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="ss">op</span><span class="p" data-group-id="2251046389-3">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="sc">$N</span><span class="nf">ewBeamOp</span><span class="p" data-group-id="8322604306-3">(</span><span class="n">S</span><span class="p">,</span><span class="w"> </span><span class="ss">op</span><span class="p" data-group-id="8322604306-3">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="2251046389-4">(</span><span class="n">Index</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_i</span><span class="w"> </span><span class="p">&amp;&amp;</span><span class="w"> </span><span class="n">Index</span><span class="p">.</span><span class="ss">val</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">&amp;&amp;</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="8322604306-4">(</span><span class="n">Index</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_i</span><span class="w"> </span><span class="p">&amp;&amp;</span><span class="w"> </span><span class="n">Index</span><span class="p">.</span><span class="ss">val</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">&amp;&amp;</span><span class="w">
│ │ │          </span><span class="n">Index</span><span class="p">.</span><span class="ss">val</span><span class="w"> </span><span class="o">&lt;=</span><span class="w"> </span><span class="n">ERTS_MAX_TUPLE_SIZE</span><span class="w"> </span><span class="p">&amp;&amp;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="2251046389-5">(</span><span class="n">Tuple</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_x</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Tuple</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_y</span><span class="p" data-group-id="2251046389-5">)</span><span class="p" data-group-id="2251046389-4">)</span><span class="w"> </span><span class="p" data-group-id="2251046389-6">{</span><span class="w">
│ │ │ -        </span><span class="sc">$B</span><span class="nf">eamOpNameArity</span><span class="p" data-group-id="2251046389-7">(</span><span class="ss">op</span><span class="p">,</span><span class="w"> </span><span class="ss">i_fast_element</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="2251046389-7">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-8">[</span><span class="mi">0</span><span class="p" data-group-id="2251046389-8">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Tuple</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-9">[</span><span class="mi">1</span><span class="p" data-group-id="2251046389-9">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Fail</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-10">[</span><span class="mi">2</span><span class="p" data-group-id="2251046389-10">]</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">TAG_u</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-11">[</span><span class="mi">2</span><span class="p" data-group-id="2251046389-11">]</span><span class="p">.</span><span class="ss">val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Index</span><span class="p">.</span><span class="ss">val</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-12">[</span><span class="mi">3</span><span class="p" data-group-id="2251046389-12">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dst</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2251046389-6">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p" data-group-id="2251046389-13">{</span><span class="w">
│ │ │ -        </span><span class="sc">$B</span><span class="nf">eamOpNameArity</span><span class="p" data-group-id="2251046389-14">(</span><span class="ss">op</span><span class="p">,</span><span class="w"> </span><span class="ss">i_element</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="2251046389-14">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-15">[</span><span class="mi">0</span><span class="p" data-group-id="2251046389-15">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Tuple</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-16">[</span><span class="mi">1</span><span class="p" data-group-id="2251046389-16">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Fail</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-17">[</span><span class="mi">2</span><span class="p" data-group-id="2251046389-17">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Index</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="2251046389-18">[</span><span class="mi">3</span><span class="p" data-group-id="2251046389-18">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dst</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="2251046389-13">}</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="8322604306-5">(</span><span class="n">Tuple</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_x</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">Tuple</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">TAG_y</span><span class="p" data-group-id="8322604306-5">)</span><span class="p" data-group-id="8322604306-4">)</span><span class="w"> </span><span class="p" data-group-id="8322604306-6">{</span><span class="w">
│ │ │ +        </span><span class="sc">$B</span><span class="nf">eamOpNameArity</span><span class="p" data-group-id="8322604306-7">(</span><span class="ss">op</span><span class="p">,</span><span class="w"> </span><span class="ss">i_fast_element</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="8322604306-7">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-8">[</span><span class="mi">0</span><span class="p" data-group-id="8322604306-8">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Tuple</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-9">[</span><span class="mi">1</span><span class="p" data-group-id="8322604306-9">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Fail</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-10">[</span><span class="mi">2</span><span class="p" data-group-id="8322604306-10">]</span><span class="p">.</span><span class="ss">type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">TAG_u</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-11">[</span><span class="mi">2</span><span class="p" data-group-id="8322604306-11">]</span><span class="p">.</span><span class="ss">val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Index</span><span class="p">.</span><span class="ss">val</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-12">[</span><span class="mi">3</span><span class="p" data-group-id="8322604306-12">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dst</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8322604306-6">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p" data-group-id="8322604306-13">{</span><span class="w">
│ │ │ +        </span><span class="sc">$B</span><span class="nf">eamOpNameArity</span><span class="p" data-group-id="8322604306-14">(</span><span class="ss">op</span><span class="p">,</span><span class="w"> </span><span class="ss">i_element</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="8322604306-14">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-15">[</span><span class="mi">0</span><span class="p" data-group-id="8322604306-15">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Tuple</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-16">[</span><span class="mi">1</span><span class="p" data-group-id="8322604306-16">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Fail</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-17">[</span><span class="mi">2</span><span class="p" data-group-id="8322604306-17">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Index</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="ss">op</span><span class="p">-&gt;</span><span class="ss">a</span><span class="p" data-group-id="8322604306-18">[</span><span class="mi">3</span><span class="p" data-group-id="8322604306-18">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Dst</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="8322604306-13">}</span><span class="w">
│ │ │  
│ │ │      </span><span class="ss">return</span><span class="w"> </span><span class="ss">op</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2251046389-2">}</span></code></pre><p>The <code class="inline">gen.</code> prefix tells <strong>beam_makeops</strong> that this function is a
│ │ │ +</span><span class="p" data-group-id="8322604306-2">}</span></code></pre><p>The <code class="inline">gen.</code> prefix tells <strong>beam_makeops</strong> that this function is a
│ │ │  generator.  Without the prefix, it would have been interpreted as the
│ │ │  implementation of an instruction (described in <strong>Defining the
│ │ │  implementation</strong>).</p><p>Generator functions have a magic variabled called <code class="inline">S</code>, which is a
│ │ │  pointer to a state struct.  In the example, <code class="inline">S</code> is used in the invocation
│ │ │  of the <code class="inline">NewBeamOp</code> macro.</p><h3 id="defining-the-implementation" class="section-heading">
│ │ │    <a href="#defining-the-implementation" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -814,473 +814,473 @@
│ │ │  </span><span class="ss">msg_instrs</span><span class="p">.</span><span class="ss">tab</span><span class="w">
│ │ │  </span><span class="ss">select_instrs</span><span class="p">.</span><span class="ss">tab</span><span class="w">
│ │ │  </span><span class="ss">trace_instrs</span><span class="p">.</span><span class="ss">tab</span></code></pre><p>There is also a file that only contains macro definitions:</p><pre><code class="makeup erlang" translate="no"><span class="ss">macros</span><span class="p">.</span><span class="ss">tab</span></code></pre><p>The syntax of each file is similar to C code.  In fact, most of
│ │ │  the contents <em>is</em> C code, interspersed with macro invocations.</p><p>To allow Emacs to auto-indent the code, each file starts with the
│ │ │  following line:</p><pre><code class="makeup erlang" translate="no"><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="o">-</span><span class="o">*</span><span class="o">-</span><span class="w"> </span><span class="ss">c</span><span class="w"> </span><span class="o">-</span><span class="o">*</span><span class="o">-</span></code></pre><p>To avoid messing up the indentation, all comments are written
│ │ │  as C++ style comments (<code class="inline">//</code>) instead of <code class="inline">#</code>.  Note that a comment
│ │ │  must start at the beginning of a line.</p><p>The meat of an instruction definition file are macro definitions.
│ │ │ -We have seen this macro definition before:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move</span><span class="p" data-group-id="1640241074-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="1640241074-1">)</span><span class="w"> </span><span class="p" data-group-id="1640241074-2">{</span><span class="w">
│ │ │ +We have seen this macro definition before:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move</span><span class="p" data-group-id="8177762067-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="8177762067-1">)</span><span class="w"> </span><span class="p" data-group-id="8177762067-2">{</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1640241074-2">}</span></code></pre><p>A macro definitions must start at the beginning of the line (no spaces
│ │ │ +</span><span class="p" data-group-id="8177762067-2">}</span></code></pre><p>A macro definitions must start at the beginning of the line (no spaces
│ │ │  allowed), the opening curly bracket must be on the same line, and the
│ │ │  finishing curly bracket must be at the beginning of a line.  It is
│ │ │  recommended that the macro body is properly indented.</p><p>As a convention, the macro arguments in the head all start with an
│ │ │  uppercase letter.  In the body, the macro arguments can be expanded
│ │ │  by preceding them with <code class="inline">$</code>.</p><p>A macro definition whose name and arity matches a family of
│ │ │  specific instructions is assumed to be the implementation of that
│ │ │  instruction.</p><p>A macro can also be invoked from within another macro.  For example,
│ │ │  <code class="inline">move_deallocate_return/2</code> avoids repeating code by invoking
│ │ │ -<code class="inline">$deallocate_return()</code> as a macro:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move_deallocate_return</span><span class="p" data-group-id="4269058280-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Deallocate</span><span class="p" data-group-id="4269058280-1">)</span><span class="w"> </span><span class="p" data-group-id="4269058280-2">{</span><span class="w">
│ │ │ -    </span><span class="nf">x</span><span class="p" data-group-id="4269058280-3">(</span><span class="mi">0</span><span class="p" data-group-id="4269058280-3">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="sc">$d</span><span class="nf">eallocate_return</span><span class="p" data-group-id="4269058280-4">(</span><span class="sc">$D</span><span class="ss">eallocate</span><span class="p" data-group-id="4269058280-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4269058280-2">}</span></code></pre><p>Here is the definition of <code class="inline">deallocate_return/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">deallocate_return</span><span class="p" data-group-id="0313001870-1">(</span><span class="n">Deallocate</span><span class="p" data-group-id="0313001870-1">)</span><span class="w"> </span><span class="p" data-group-id="0313001870-2">{</span><span class="w">
│ │ │ +<code class="inline">$deallocate_return()</code> as a macro:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move_deallocate_return</span><span class="p" data-group-id="9055073898-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Deallocate</span><span class="p" data-group-id="9055073898-1">)</span><span class="w"> </span><span class="p" data-group-id="9055073898-2">{</span><span class="w">
│ │ │ +    </span><span class="nf">x</span><span class="p" data-group-id="9055073898-3">(</span><span class="mi">0</span><span class="p" data-group-id="9055073898-3">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="sc">$d</span><span class="nf">eallocate_return</span><span class="p" data-group-id="9055073898-4">(</span><span class="sc">$D</span><span class="ss">eallocate</span><span class="p" data-group-id="9055073898-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9055073898-2">}</span></code></pre><p>Here is the definition of <code class="inline">deallocate_return/1</code>:</p><pre><code class="makeup erlang" translate="no"><span class="nf">deallocate_return</span><span class="p" data-group-id="4649615110-1">(</span><span class="n">Deallocate</span><span class="p" data-group-id="4649615110-1">)</span><span class="w"> </span><span class="p" data-group-id="4649615110-2">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="p">|</span><span class="w"> </span><span class="o">-</span><span class="ss">no_next</span><span class="w">
│ │ │      </span><span class="ss">int</span><span class="w"> </span><span class="ss">words_to_pop</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$D</span><span class="ss">eallocate</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">SET_I</span><span class="p" data-group-id="0313001870-3">(</span><span class="p" data-group-id="0313001870-4">(</span><span class="n">BeamInstr</span><span class="w"> </span><span class="o">*</span><span class="p" data-group-id="0313001870-4">)</span><span class="w"> </span><span class="nf">cp_val</span><span class="p" data-group-id="0313001870-5">(</span><span class="o">*</span><span class="n">E</span><span class="p" data-group-id="0313001870-5">)</span><span class="p" data-group-id="0313001870-3">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">E</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ADD_BYTE_OFFSET</span><span class="p" data-group-id="0313001870-6">(</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="ss">words_to_pop</span><span class="p" data-group-id="0313001870-6">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">CHECK_TERM</span><span class="p" data-group-id="0313001870-7">(</span><span class="nf">x</span><span class="p" data-group-id="0313001870-8">(</span><span class="mi">0</span><span class="p" data-group-id="0313001870-8">)</span><span class="p" data-group-id="0313001870-7">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">SET_I</span><span class="p" data-group-id="4649615110-3">(</span><span class="p" data-group-id="4649615110-4">(</span><span class="n">BeamInstr</span><span class="w"> </span><span class="o">*</span><span class="p" data-group-id="4649615110-4">)</span><span class="w"> </span><span class="nf">cp_val</span><span class="p" data-group-id="4649615110-5">(</span><span class="o">*</span><span class="n">E</span><span class="p" data-group-id="4649615110-5">)</span><span class="p" data-group-id="4649615110-3">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">E</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ADD_BYTE_OFFSET</span><span class="p" data-group-id="4649615110-6">(</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="ss">words_to_pop</span><span class="p" data-group-id="4649615110-6">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">CHECK_TERM</span><span class="p" data-group-id="4649615110-7">(</span><span class="nf">x</span><span class="p" data-group-id="4649615110-8">(</span><span class="mi">0</span><span class="p" data-group-id="4649615110-8">)</span><span class="p" data-group-id="4649615110-7">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">DispatchReturn</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0313001870-2">}</span></code></pre><p>The expanded code for <code class="inline">move_deallocate_return</code> will look this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="6979870227-1">(</span><span class="ss">move_deallocate_return_cQ</span><span class="p" data-group-id="6979870227-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6979870227-2">{</span><span class="w">
│ │ │ -  </span><span class="nf">x</span><span class="p" data-group-id="6979870227-3">(</span><span class="mi">0</span><span class="p" data-group-id="6979870227-3">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="6979870227-4">[</span><span class="mi">1</span><span class="p" data-group-id="6979870227-4">]</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="ss">do</span><span class="w"> </span><span class="p" data-group-id="6979870227-5">{</span><span class="w">
│ │ │ -    </span><span class="ss">int</span><span class="w"> </span><span class="ss">words_to_pop</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Qb</span><span class="p" data-group-id="6979870227-6">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="6979870227-7">(</span><span class="n">I</span><span class="p" data-group-id="6979870227-8">[</span><span class="mi">0</span><span class="p" data-group-id="6979870227-8">]</span><span class="p" data-group-id="6979870227-7">)</span><span class="p" data-group-id="6979870227-6">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">SET_I</span><span class="p" data-group-id="6979870227-9">(</span><span class="p" data-group-id="6979870227-10">(</span><span class="n">BeamInstr</span><span class="w"> </span><span class="o">*</span><span class="p" data-group-id="6979870227-10">)</span><span class="w"> </span><span class="nf">cp_val</span><span class="p" data-group-id="6979870227-11">(</span><span class="o">*</span><span class="n">E</span><span class="p" data-group-id="6979870227-11">)</span><span class="p" data-group-id="6979870227-9">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">E</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ADD_BYTE_OFFSET</span><span class="p" data-group-id="6979870227-12">(</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="ss">words_to_pop</span><span class="p" data-group-id="6979870227-12">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">CHECK_TERM</span><span class="p" data-group-id="6979870227-13">(</span><span class="nf">x</span><span class="p" data-group-id="6979870227-14">(</span><span class="mi">0</span><span class="p" data-group-id="6979870227-14">)</span><span class="p" data-group-id="6979870227-13">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4649615110-2">}</span></code></pre><p>The expanded code for <code class="inline">move_deallocate_return</code> will look this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="2039203246-1">(</span><span class="ss">move_deallocate_return_cQ</span><span class="p" data-group-id="2039203246-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2039203246-2">{</span><span class="w">
│ │ │ +  </span><span class="nf">x</span><span class="p" data-group-id="2039203246-3">(</span><span class="mi">0</span><span class="p" data-group-id="2039203246-3">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="2039203246-4">[</span><span class="mi">1</span><span class="p" data-group-id="2039203246-4">]</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="ss">do</span><span class="w"> </span><span class="p" data-group-id="2039203246-5">{</span><span class="w">
│ │ │ +    </span><span class="ss">int</span><span class="w"> </span><span class="ss">words_to_pop</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Qb</span><span class="p" data-group-id="2039203246-6">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="2039203246-7">(</span><span class="n">I</span><span class="p" data-group-id="2039203246-8">[</span><span class="mi">0</span><span class="p" data-group-id="2039203246-8">]</span><span class="p" data-group-id="2039203246-7">)</span><span class="p" data-group-id="2039203246-6">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">SET_I</span><span class="p" data-group-id="2039203246-9">(</span><span class="p" data-group-id="2039203246-10">(</span><span class="n">BeamInstr</span><span class="w"> </span><span class="o">*</span><span class="p" data-group-id="2039203246-10">)</span><span class="w"> </span><span class="nf">cp_val</span><span class="p" data-group-id="2039203246-11">(</span><span class="o">*</span><span class="n">E</span><span class="p" data-group-id="2039203246-11">)</span><span class="p" data-group-id="2039203246-9">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">E</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ADD_BYTE_OFFSET</span><span class="p" data-group-id="2039203246-12">(</span><span class="n">E</span><span class="p">,</span><span class="w"> </span><span class="ss">words_to_pop</span><span class="p" data-group-id="2039203246-12">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">CHECK_TERM</span><span class="p" data-group-id="2039203246-13">(</span><span class="nf">x</span><span class="p" data-group-id="2039203246-14">(</span><span class="mi">0</span><span class="p" data-group-id="2039203246-14">)</span><span class="p" data-group-id="2039203246-13">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">DispatchReturn</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="6979870227-5">}</span><span class="w"> </span><span class="nf">while</span><span class="w"> </span><span class="p" data-group-id="6979870227-15">(</span><span class="mi">0</span><span class="p" data-group-id="6979870227-15">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6979870227-2">}</span></code></pre><p>When expanding macros, <strong>beam_makeops</strong> wraps the expansion in a
│ │ │ +  </span><span class="p" data-group-id="2039203246-5">}</span><span class="w"> </span><span class="nf">while</span><span class="w"> </span><span class="p" data-group-id="2039203246-15">(</span><span class="mi">0</span><span class="p" data-group-id="2039203246-15">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2039203246-2">}</span></code></pre><p>When expanding macros, <strong>beam_makeops</strong> wraps the expansion in a
│ │ │  <code class="inline">do</code>/<code class="inline">while</code> wrapper unless <strong>beam_makeops</strong> can clearly see that no
│ │ │  wrapper is needed.  In this case, the wrapper is needed.</p><p>Note that arguments for macros cannot be complex expressions, because
│ │ │  the arguments are split on <code class="inline">,</code>.  For example, the following would
│ │ │  not work because <strong>beam_makeops</strong> would split the expression into
│ │ │ -two arguments:</p><pre><code class="makeup erlang" translate="no"><span class="sc">$d</span><span class="nf">eallocate_return</span><span class="p" data-group-id="1162471222-1">(</span><span class="nf">get_deallocation</span><span class="p" data-group-id="1162471222-2">(</span><span class="ss">y</span><span class="p">,</span><span class="w"> </span><span class="sc">$D</span><span class="ss">eallocate</span><span class="p" data-group-id="1162471222-2">)</span><span class="p" data-group-id="1162471222-1">)</span><span class="p">;</span></code></pre><h4>Code generation directives</h4><p>Within macro definitions, <code class="inline">//</code> comments are in general not treated
│ │ │ +two arguments:</p><pre><code class="makeup erlang" translate="no"><span class="sc">$d</span><span class="nf">eallocate_return</span><span class="p" data-group-id="6404835776-1">(</span><span class="nf">get_deallocation</span><span class="p" data-group-id="6404835776-2">(</span><span class="ss">y</span><span class="p">,</span><span class="w"> </span><span class="sc">$D</span><span class="ss">eallocate</span><span class="p" data-group-id="6404835776-2">)</span><span class="p" data-group-id="6404835776-1">)</span><span class="p">;</span></code></pre><h4>Code generation directives</h4><p>Within macro definitions, <code class="inline">//</code> comments are in general not treated
│ │ │  specially.  They will be copied to the file with the generated code
│ │ │  along with the rest of code in the body.</p><p>However, there is an exception. Within a macro definition, a line that
│ │ │  starts with whitespace followed by <code class="inline">//|</code> is treated specially.  The
│ │ │  rest of the line is assumed to contain directives to control code
│ │ │  generation.</p><p>Currently, two code generation directives are recognized:</p><ul><li><code class="inline">-no_prefetch</code></li><li><code class="inline">-no_next</code></li></ul><h5>The -no_prefetch directive</h5><p>To see what <code class="inline">-no_prefetch</code> does, let's first look at the default code
│ │ │ -generation.  Here is the code generated for <code class="inline">move_cx</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="5559023387-1">(</span><span class="ss">move_cx</span><span class="p" data-group-id="5559023387-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5559023387-2">{</span><span class="w">
│ │ │ -  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="5559023387-3">(</span><span class="n">I</span><span class="p" data-group-id="5559023387-4">[</span><span class="mi">2</span><span class="p" data-group-id="5559023387-4">]</span><span class="p" data-group-id="5559023387-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="nf">xb</span><span class="p" data-group-id="5559023387-5">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="5559023387-6">(</span><span class="n">I</span><span class="p" data-group-id="5559023387-7">[</span><span class="mi">0</span><span class="p" data-group-id="5559023387-7">]</span><span class="p" data-group-id="5559023387-6">)</span><span class="p" data-group-id="5559023387-5">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="5559023387-8">[</span><span class="mi">1</span><span class="p" data-group-id="5559023387-8">]</span><span class="p">;</span><span class="w">
│ │ │ +generation.  Here is the code generated for <code class="inline">move_cx</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="7645989443-1">(</span><span class="ss">move_cx</span><span class="p" data-group-id="7645989443-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7645989443-2">{</span><span class="w">
│ │ │ +  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="7645989443-3">(</span><span class="n">I</span><span class="p" data-group-id="7645989443-4">[</span><span class="mi">2</span><span class="p" data-group-id="7645989443-4">]</span><span class="p" data-group-id="7645989443-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="nf">xb</span><span class="p" data-group-id="7645989443-5">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="7645989443-6">(</span><span class="n">I</span><span class="p" data-group-id="7645989443-7">[</span><span class="mi">0</span><span class="p" data-group-id="7645989443-7">]</span><span class="p" data-group-id="7645989443-6">)</span><span class="p" data-group-id="7645989443-5">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="7645989443-8">[</span><span class="mi">1</span><span class="p" data-group-id="7645989443-8">]</span><span class="p">;</span><span class="w">
│ │ │    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="5559023387-9">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="5559023387-10">(</span><span class="ss">next_pf</span><span class="p" data-group-id="5559023387-10">)</span><span class="p" data-group-id="5559023387-9">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">GotoPF</span><span class="p" data-group-id="5559023387-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="5559023387-11">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5559023387-2">}</span></code></pre><p>Note that the very first thing done is to fetch the address to the
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="7645989443-9">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="7645989443-10">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7645989443-10">)</span><span class="p" data-group-id="7645989443-9">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">GotoPF</span><span class="p" data-group-id="7645989443-11">(</span><span class="ss">next_pf</span><span class="p" data-group-id="7645989443-11">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7645989443-2">}</span></code></pre><p>Note that the very first thing done is to fetch the address to the
│ │ │  next instruction.  The reason is that it usually improves performance.</p><p>Just as a demonstration, we can add a <code class="inline">-no_prefetch</code> directive to
│ │ │ -the <code class="inline">move/2</code> instruction:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move</span><span class="p" data-group-id="0049792646-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="0049792646-1">)</span><span class="w"> </span><span class="p" data-group-id="0049792646-2">{</span><span class="w">
│ │ │ +the <code class="inline">move/2</code> instruction:</p><pre><code class="makeup erlang" translate="no"><span class="nf">move</span><span class="p" data-group-id="0797874533-1">(</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="0797874533-1">)</span><span class="w"> </span><span class="p" data-group-id="0797874533-2">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="p">|</span><span class="w"> </span><span class="o">-</span><span class="ss">no_prefetch</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0049792646-2">}</span></code></pre><p>We can see that the prefetch is no longer done:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="7978299952-1">(</span><span class="ss">move_cx</span><span class="p" data-group-id="7978299952-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7978299952-2">{</span><span class="w">
│ │ │ -  </span><span class="nf">xb</span><span class="p" data-group-id="7978299952-3">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="7978299952-4">(</span><span class="n">I</span><span class="p" data-group-id="7978299952-5">[</span><span class="mi">0</span><span class="p" data-group-id="7978299952-5">]</span><span class="p" data-group-id="7978299952-4">)</span><span class="p" data-group-id="7978299952-3">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="7978299952-6">[</span><span class="mi">1</span><span class="p" data-group-id="7978299952-6">]</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0797874533-2">}</span></code></pre><p>We can see that the prefetch is no longer done:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="7647713255-1">(</span><span class="ss">move_cx</span><span class="p" data-group-id="7647713255-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7647713255-2">{</span><span class="w">
│ │ │ +  </span><span class="nf">xb</span><span class="p" data-group-id="7647713255-3">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="7647713255-4">(</span><span class="n">I</span><span class="p" data-group-id="7647713255-5">[</span><span class="mi">0</span><span class="p" data-group-id="7647713255-5">]</span><span class="p" data-group-id="7647713255-4">)</span><span class="p" data-group-id="7647713255-3">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="7647713255-6">[</span><span class="mi">1</span><span class="p" data-group-id="7647713255-6">]</span><span class="p">;</span><span class="w">
│ │ │    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="7978299952-7">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="7978299952-8">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="7978299952-8">)</span><span class="p" data-group-id="7978299952-7">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">Goto</span><span class="p" data-group-id="7978299952-9">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="7978299952-9">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7978299952-2">}</span></code></pre><p>When would we want to turn off the prefetch in practice?</p><p>In instructions that will not always execute the next instruction.
│ │ │ -For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">is_atom</span><span class="p" data-group-id="6538893185-1">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Src</span><span class="p" data-group-id="6538893185-1">)</span><span class="w"> </span><span class="p" data-group-id="6538893185-2">{</span><span class="w">
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="6538893185-3">(</span><span class="nf">is_not_atom</span><span class="p" data-group-id="6538893185-4">(</span><span class="sc">$S</span><span class="ss">rc</span><span class="p" data-group-id="6538893185-4">)</span><span class="p" data-group-id="6538893185-3">)</span><span class="w"> </span><span class="p" data-group-id="6538893185-5">{</span><span class="w">
│ │ │ -        </span><span class="sc">$F</span><span class="n">AIL</span><span class="p" data-group-id="6538893185-6">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="6538893185-6">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="6538893185-5">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6538893185-2">}</span><span class="w">
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="7647713255-7">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="7647713255-8">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="7647713255-8">)</span><span class="p" data-group-id="7647713255-7">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">Goto</span><span class="p" data-group-id="7647713255-9">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="7647713255-9">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7647713255-2">}</span></code></pre><p>When would we want to turn off the prefetch in practice?</p><p>In instructions that will not always execute the next instruction.
│ │ │ +For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">is_atom</span><span class="p" data-group-id="4664824795-1">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Src</span><span class="p" data-group-id="4664824795-1">)</span><span class="w"> </span><span class="p" data-group-id="4664824795-2">{</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="4664824795-3">(</span><span class="nf">is_not_atom</span><span class="p" data-group-id="4664824795-4">(</span><span class="sc">$S</span><span class="ss">rc</span><span class="p" data-group-id="4664824795-4">)</span><span class="p" data-group-id="4664824795-3">)</span><span class="w"> </span><span class="p" data-group-id="4664824795-5">{</span><span class="w">
│ │ │ +        </span><span class="sc">$F</span><span class="n">AIL</span><span class="p" data-group-id="4664824795-6">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="4664824795-6">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="4664824795-5">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4664824795-2">}</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">From</span><span class="w"> </span><span class="ss">macros</span><span class="p">.</span><span class="ss">tab</span><span class="w">
│ │ │ -</span><span class="n">FAIL</span><span class="p" data-group-id="6538893185-7">(</span><span class="n">Fail</span><span class="p" data-group-id="6538893185-7">)</span><span class="w"> </span><span class="p" data-group-id="6538893185-8">{</span><span class="w">
│ │ │ +</span><span class="n">FAIL</span><span class="p" data-group-id="4664824795-7">(</span><span class="n">Fail</span><span class="p" data-group-id="4664824795-7">)</span><span class="w"> </span><span class="p" data-group-id="4664824795-8">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="p">|</span><span class="w"> </span><span class="o">-</span><span class="ss">no_prefetch</span><span class="w">
│ │ │ -    </span><span class="sc">$S</span><span class="n">ET_I_REL</span><span class="p" data-group-id="6538893185-9">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="6538893185-9">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">Goto</span><span class="p" data-group-id="6538893185-10">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="6538893185-10">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6538893185-8">}</span></code></pre><p><code class="inline">is_atom/2</code> may either execute the next instruction (if the second
│ │ │ -operand is an atom) or branch to the failure label.</p><p>The generated code looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="4279174744-1">(</span><span class="ss">is_atom_fx</span><span class="p" data-group-id="4279174744-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4279174744-2">{</span><span class="w">
│ │ │ -  </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="4279174744-3">(</span><span class="nf">is_not_atom</span><span class="p" data-group-id="4279174744-4">(</span><span class="nf">xb</span><span class="p" data-group-id="4279174744-5">(</span><span class="n">I</span><span class="p" data-group-id="4279174744-6">[</span><span class="mi">1</span><span class="p" data-group-id="4279174744-6">]</span><span class="p" data-group-id="4279174744-5">)</span><span class="p" data-group-id="4279174744-4">)</span><span class="p" data-group-id="4279174744-3">)</span><span class="w"> </span><span class="p" data-group-id="4279174744-7">{</span><span class="w">
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="4279174744-8">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="4279174744-9">(</span><span class="o">*</span><span class="p" data-group-id="4279174744-10">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="4279174744-11">(</span><span class="nf">fb</span><span class="p" data-group-id="4279174744-12">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="4279174744-13">(</span><span class="n">I</span><span class="p" data-group-id="4279174744-14">[</span><span class="mi">0</span><span class="p" data-group-id="4279174744-14">]</span><span class="p" data-group-id="4279174744-13">)</span><span class="p" data-group-id="4279174744-12">)</span><span class="p" data-group-id="4279174744-11">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4279174744-10">)</span><span class="p" data-group-id="4279174744-9">)</span><span class="p" data-group-id="4279174744-8">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">fb</span><span class="p" data-group-id="4279174744-15">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="4279174744-16">(</span><span class="n">I</span><span class="p" data-group-id="4279174744-17">[</span><span class="mi">0</span><span class="p" data-group-id="4279174744-17">]</span><span class="p" data-group-id="4279174744-16">)</span><span class="p" data-group-id="4279174744-15">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">Goto</span><span class="p" data-group-id="4279174744-18">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="4279174744-18">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="4279174744-7">}</span><span class="w">
│ │ │ +    </span><span class="sc">$S</span><span class="n">ET_I_REL</span><span class="p" data-group-id="4664824795-9">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="4664824795-9">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">Goto</span><span class="p" data-group-id="4664824795-10">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="4664824795-10">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4664824795-8">}</span></code></pre><p><code class="inline">is_atom/2</code> may either execute the next instruction (if the second
│ │ │ +operand is an atom) or branch to the failure label.</p><p>The generated code looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="6985592623-1">(</span><span class="ss">is_atom_fx</span><span class="p" data-group-id="6985592623-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6985592623-2">{</span><span class="w">
│ │ │ +  </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="6985592623-3">(</span><span class="nf">is_not_atom</span><span class="p" data-group-id="6985592623-4">(</span><span class="nf">xb</span><span class="p" data-group-id="6985592623-5">(</span><span class="n">I</span><span class="p" data-group-id="6985592623-6">[</span><span class="mi">1</span><span class="p" data-group-id="6985592623-6">]</span><span class="p" data-group-id="6985592623-5">)</span><span class="p" data-group-id="6985592623-4">)</span><span class="p" data-group-id="6985592623-3">)</span><span class="w"> </span><span class="p" data-group-id="6985592623-7">{</span><span class="w">
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="6985592623-8">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="6985592623-9">(</span><span class="o">*</span><span class="p" data-group-id="6985592623-10">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="6985592623-11">(</span><span class="nf">fb</span><span class="p" data-group-id="6985592623-12">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="6985592623-13">(</span><span class="n">I</span><span class="p" data-group-id="6985592623-14">[</span><span class="mi">0</span><span class="p" data-group-id="6985592623-14">]</span><span class="p" data-group-id="6985592623-13">)</span><span class="p" data-group-id="6985592623-12">)</span><span class="p" data-group-id="6985592623-11">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="6985592623-10">)</span><span class="p" data-group-id="6985592623-9">)</span><span class="p" data-group-id="6985592623-8">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">fb</span><span class="p" data-group-id="6985592623-15">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="6985592623-16">(</span><span class="n">I</span><span class="p" data-group-id="6985592623-17">[</span><span class="mi">0</span><span class="p" data-group-id="6985592623-17">]</span><span class="p" data-group-id="6985592623-16">)</span><span class="p" data-group-id="6985592623-15">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">Goto</span><span class="p" data-group-id="6985592623-18">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="6985592623-18">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="6985592623-7">}</span><span class="w">
│ │ │    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="mi">2</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="4279174744-19">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="4279174744-20">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="4279174744-20">)</span><span class="p" data-group-id="4279174744-19">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">Goto</span><span class="p" data-group-id="4279174744-21">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="4279174744-21">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4279174744-2">}</span></code></pre><h5>The -no_next directive</h5><p>Next we will look at when the <code class="inline">-no_next</code> directive can be used.  Here
│ │ │ -is the <code class="inline">jump/1</code> instruction:</p><pre><code class="makeup erlang" translate="no"><span class="nf">jump</span><span class="p" data-group-id="9200945458-1">(</span><span class="n">Fail</span><span class="p" data-group-id="9200945458-1">)</span><span class="w"> </span><span class="p" data-group-id="9200945458-2">{</span><span class="w">
│ │ │ -    </span><span class="sc">$J</span><span class="n">UMP</span><span class="p" data-group-id="9200945458-3">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="9200945458-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9200945458-2">}</span><span class="w">
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="6985592623-19">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="6985592623-20">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="6985592623-20">)</span><span class="p" data-group-id="6985592623-19">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">Goto</span><span class="p" data-group-id="6985592623-21">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="6985592623-21">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6985592623-2">}</span></code></pre><h5>The -no_next directive</h5><p>Next we will look at when the <code class="inline">-no_next</code> directive can be used.  Here
│ │ │ +is the <code class="inline">jump/1</code> instruction:</p><pre><code class="makeup erlang" translate="no"><span class="nf">jump</span><span class="p" data-group-id="8462715028-1">(</span><span class="n">Fail</span><span class="p" data-group-id="8462715028-1">)</span><span class="w"> </span><span class="p" data-group-id="8462715028-2">{</span><span class="w">
│ │ │ +    </span><span class="sc">$J</span><span class="n">UMP</span><span class="p" data-group-id="8462715028-3">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="8462715028-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8462715028-2">}</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">From</span><span class="w"> </span><span class="ss">macros</span><span class="p">.</span><span class="ss">tab</span><span class="w">
│ │ │ -</span><span class="n">JUMP</span><span class="p" data-group-id="9200945458-4">(</span><span class="n">Fail</span><span class="p" data-group-id="9200945458-4">)</span><span class="w"> </span><span class="p" data-group-id="9200945458-5">{</span><span class="w">
│ │ │ +</span><span class="n">JUMP</span><span class="p" data-group-id="8462715028-4">(</span><span class="n">Fail</span><span class="p" data-group-id="8462715028-4">)</span><span class="w"> </span><span class="p" data-group-id="8462715028-5">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="p">|</span><span class="w"> </span><span class="o">-</span><span class="ss">no_next</span><span class="w">
│ │ │ -    </span><span class="sc">$S</span><span class="n">ET_I_REL</span><span class="p" data-group-id="9200945458-6">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="9200945458-6">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">Goto</span><span class="p" data-group-id="9200945458-7">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="9200945458-7">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9200945458-5">}</span></code></pre><p>The generated code looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="3474590151-1">(</span><span class="ss">jump_f</span><span class="p" data-group-id="3474590151-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3474590151-2">{</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="3474590151-3">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="3474590151-4">(</span><span class="o">*</span><span class="p" data-group-id="3474590151-5">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="3474590151-6">(</span><span class="nf">fb</span><span class="p" data-group-id="3474590151-7">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="3474590151-8">(</span><span class="n">I</span><span class="p" data-group-id="3474590151-9">[</span><span class="mi">0</span><span class="p" data-group-id="3474590151-9">]</span><span class="p" data-group-id="3474590151-8">)</span><span class="p" data-group-id="3474590151-7">)</span><span class="p" data-group-id="3474590151-6">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3474590151-5">)</span><span class="p" data-group-id="3474590151-4">)</span><span class="p" data-group-id="3474590151-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">fb</span><span class="p" data-group-id="3474590151-10">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="3474590151-11">(</span><span class="n">I</span><span class="p" data-group-id="3474590151-12">[</span><span class="mi">0</span><span class="p" data-group-id="3474590151-12">]</span><span class="p" data-group-id="3474590151-11">)</span><span class="p" data-group-id="3474590151-10">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">Goto</span><span class="p" data-group-id="3474590151-13">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="3474590151-13">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3474590151-2">}</span></code></pre><p>If we remove the <code class="inline">-no_next</code> directive, the code would look like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="5886670200-1">(</span><span class="ss">jump_f</span><span class="p" data-group-id="5886670200-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5886670200-2">{</span><span class="w">
│ │ │ -  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="5886670200-3">(</span><span class="n">I</span><span class="p" data-group-id="5886670200-4">[</span><span class="mi">1</span><span class="p" data-group-id="5886670200-4">]</span><span class="p" data-group-id="5886670200-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="5886670200-5">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="5886670200-6">(</span><span class="o">*</span><span class="p" data-group-id="5886670200-7">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="5886670200-8">(</span><span class="nf">fb</span><span class="p" data-group-id="5886670200-9">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="5886670200-10">(</span><span class="n">I</span><span class="p" data-group-id="5886670200-11">[</span><span class="mi">0</span><span class="p" data-group-id="5886670200-11">]</span><span class="p" data-group-id="5886670200-10">)</span><span class="p" data-group-id="5886670200-9">)</span><span class="p" data-group-id="5886670200-8">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="5886670200-7">)</span><span class="p" data-group-id="5886670200-6">)</span><span class="p" data-group-id="5886670200-5">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">fb</span><span class="p" data-group-id="5886670200-12">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="5886670200-13">(</span><span class="n">I</span><span class="p" data-group-id="5886670200-14">[</span><span class="mi">0</span><span class="p" data-group-id="5886670200-14">]</span><span class="p" data-group-id="5886670200-13">)</span><span class="p" data-group-id="5886670200-12">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">Goto</span><span class="p" data-group-id="5886670200-15">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="5886670200-15">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="sc">$S</span><span class="n">ET_I_REL</span><span class="p" data-group-id="8462715028-6">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="8462715028-6">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">Goto</span><span class="p" data-group-id="8462715028-7">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="8462715028-7">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8462715028-5">}</span></code></pre><p>The generated code looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="9097108119-1">(</span><span class="ss">jump_f</span><span class="p" data-group-id="9097108119-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9097108119-2">{</span><span class="w">
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="9097108119-3">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="9097108119-4">(</span><span class="o">*</span><span class="p" data-group-id="9097108119-5">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="9097108119-6">(</span><span class="nf">fb</span><span class="p" data-group-id="9097108119-7">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="9097108119-8">(</span><span class="n">I</span><span class="p" data-group-id="9097108119-9">[</span><span class="mi">0</span><span class="p" data-group-id="9097108119-9">]</span><span class="p" data-group-id="9097108119-8">)</span><span class="p" data-group-id="9097108119-7">)</span><span class="p" data-group-id="9097108119-6">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="9097108119-5">)</span><span class="p" data-group-id="9097108119-4">)</span><span class="p" data-group-id="9097108119-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">fb</span><span class="p" data-group-id="9097108119-10">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="9097108119-11">(</span><span class="n">I</span><span class="p" data-group-id="9097108119-12">[</span><span class="mi">0</span><span class="p" data-group-id="9097108119-12">]</span><span class="p" data-group-id="9097108119-11">)</span><span class="p" data-group-id="9097108119-10">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">Goto</span><span class="p" data-group-id="9097108119-13">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="9097108119-13">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9097108119-2">}</span></code></pre><p>If we remove the <code class="inline">-no_next</code> directive, the code would look like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="3655730572-1">(</span><span class="ss">jump_f</span><span class="p" data-group-id="3655730572-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3655730572-2">{</span><span class="w">
│ │ │ +  </span><span class="n">BeamInstr</span><span class="w"> </span><span class="ss">next_pf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BeamCodeAddr</span><span class="p" data-group-id="3655730572-3">(</span><span class="n">I</span><span class="p" data-group-id="3655730572-4">[</span><span class="mi">1</span><span class="p" data-group-id="3655730572-4">]</span><span class="p" data-group-id="3655730572-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="3655730572-5">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="3655730572-6">(</span><span class="o">*</span><span class="p" data-group-id="3655730572-7">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="3655730572-8">(</span><span class="nf">fb</span><span class="p" data-group-id="3655730572-9">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="3655730572-10">(</span><span class="n">I</span><span class="p" data-group-id="3655730572-11">[</span><span class="mi">0</span><span class="p" data-group-id="3655730572-11">]</span><span class="p" data-group-id="3655730572-10">)</span><span class="p" data-group-id="3655730572-9">)</span><span class="p" data-group-id="3655730572-8">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3655730572-7">)</span><span class="p" data-group-id="3655730572-6">)</span><span class="p" data-group-id="3655730572-5">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="nf">fb</span><span class="p" data-group-id="3655730572-12">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="3655730572-13">(</span><span class="n">I</span><span class="p" data-group-id="3655730572-14">[</span><span class="mi">0</span><span class="p" data-group-id="3655730572-14">]</span><span class="p" data-group-id="3655730572-13">)</span><span class="p" data-group-id="3655730572-12">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">Goto</span><span class="p" data-group-id="3655730572-15">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="3655730572-15">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │    </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">ASSERT</span><span class="p" data-group-id="5886670200-16">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="5886670200-17">(</span><span class="ss">next_pf</span><span class="p" data-group-id="5886670200-17">)</span><span class="p" data-group-id="5886670200-16">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">GotoPF</span><span class="p" data-group-id="5886670200-18">(</span><span class="ss">next_pf</span><span class="p" data-group-id="5886670200-18">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5886670200-2">}</span></code></pre><p>In the end, the C compiler will probably optimize this code to the
│ │ │ +  </span><span class="n">ASSERT</span><span class="p" data-group-id="3655730572-16">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="3655730572-17">(</span><span class="ss">next_pf</span><span class="p" data-group-id="3655730572-17">)</span><span class="p" data-group-id="3655730572-16">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="n">GotoPF</span><span class="p" data-group-id="3655730572-18">(</span><span class="ss">next_pf</span><span class="p" data-group-id="3655730572-18">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3655730572-2">}</span></code></pre><p>In the end, the C compiler will probably optimize this code to the
│ │ │  same native code as the first version, but the first version is certainly
│ │ │  much easier to read for human readers.</p><h4>Macros in the macros.tab file</h4><p>The file <code class="inline">macros.tab</code> contains many useful macros.  When implementing
│ │ │  new instructions it is good practice to look through <code class="inline">macros.tab</code> to
│ │ │  see if any of existing macros can be used rather than re-inventing
│ │ │  the wheel.</p><p>We will describe a few of the most useful macros here.</p><p><a href="" id="the-GC_REGEXP-definition"></a></p><h5>The GC_REGEXP definition</h5><p>The following line defines a regular expression that will recognize
│ │ │  a call to a function that does a garbage collection:</p><pre><code class="makeup erlang" translate="no"><span class="w"> </span><span class="n">GC_REGEXP</span><span class="o">=</span><span class="ss">erts_garbage_collect</span><span class="p">|</span><span class="ss">erts_gc</span><span class="p">|</span><span class="n">GcBifFunction</span><span class="p">;</span></code></pre><p>The purpose is that <strong>beam_makeops</strong> can verify that an instruction
│ │ │  that does a garbage collection and has an <code class="inline">d</code> operand uses the
│ │ │  <code class="inline">$REFRESH_GEN_DEST()</code> macro.</p><p>If you need to define a new function that does garbage collection,
│ │ │  you should give it the prefix <code class="inline">erts_gc_</code>.  If that is not possible
│ │ │  you should update the regular expression so that it will match your
│ │ │ -new function.</p><h5>FAIL(Fail)</h5><p>Branch to <code class="inline">$Fail</code>.  Will suppress prefetch (<code class="inline">-no_prefetch</code>).  Typical use:</p><pre><code class="makeup erlang" translate="no"><span class="nf">is_nonempty_list</span><span class="p" data-group-id="0856696633-1">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Src</span><span class="p" data-group-id="0856696633-1">)</span><span class="w"> </span><span class="p" data-group-id="0856696633-2">{</span><span class="w">
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="0856696633-3">(</span><span class="nf">is_not_list</span><span class="p" data-group-id="0856696633-4">(</span><span class="sc">$S</span><span class="ss">rc</span><span class="p" data-group-id="0856696633-4">)</span><span class="p" data-group-id="0856696633-3">)</span><span class="w"> </span><span class="p" data-group-id="0856696633-5">{</span><span class="w">
│ │ │ -        </span><span class="sc">$F</span><span class="n">AIL</span><span class="p" data-group-id="0856696633-6">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="0856696633-6">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0856696633-5">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0856696633-2">}</span></code></pre><h5>JUMP(Fail)</h5><p>Branch to <code class="inline">$Fail</code>.  Suppresses generation of dispatch of the next
│ │ │ -instruction (<code class="inline">-no_next</code>).  Typical use:</p><pre><code class="makeup erlang" translate="no"><span class="nf">jump</span><span class="p" data-group-id="6661282185-1">(</span><span class="n">Fail</span><span class="p" data-group-id="6661282185-1">)</span><span class="w"> </span><span class="p" data-group-id="6661282185-2">{</span><span class="w">
│ │ │ -    </span><span class="sc">$J</span><span class="n">UMP</span><span class="p" data-group-id="6661282185-3">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="6661282185-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6661282185-2">}</span></code></pre><h5>GC_TEST(NeedStack, NeedHeap, Live)</h5><p><code class="inline">$GC_TEST(NeedStack, NeedHeap, Live)</code> tests that given amount of
│ │ │ +new function.</p><h5>FAIL(Fail)</h5><p>Branch to <code class="inline">$Fail</code>.  Will suppress prefetch (<code class="inline">-no_prefetch</code>).  Typical use:</p><pre><code class="makeup erlang" translate="no"><span class="nf">is_nonempty_list</span><span class="p" data-group-id="7378252324-1">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Src</span><span class="p" data-group-id="7378252324-1">)</span><span class="w"> </span><span class="p" data-group-id="7378252324-2">{</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="7378252324-3">(</span><span class="nf">is_not_list</span><span class="p" data-group-id="7378252324-4">(</span><span class="sc">$S</span><span class="ss">rc</span><span class="p" data-group-id="7378252324-4">)</span><span class="p" data-group-id="7378252324-3">)</span><span class="w"> </span><span class="p" data-group-id="7378252324-5">{</span><span class="w">
│ │ │ +        </span><span class="sc">$F</span><span class="n">AIL</span><span class="p" data-group-id="7378252324-6">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="7378252324-6">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="7378252324-5">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7378252324-2">}</span></code></pre><h5>JUMP(Fail)</h5><p>Branch to <code class="inline">$Fail</code>.  Suppresses generation of dispatch of the next
│ │ │ +instruction (<code class="inline">-no_next</code>).  Typical use:</p><pre><code class="makeup erlang" translate="no"><span class="nf">jump</span><span class="p" data-group-id="0483098362-1">(</span><span class="n">Fail</span><span class="p" data-group-id="0483098362-1">)</span><span class="w"> </span><span class="p" data-group-id="0483098362-2">{</span><span class="w">
│ │ │ +    </span><span class="sc">$J</span><span class="n">UMP</span><span class="p" data-group-id="0483098362-3">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="0483098362-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0483098362-2">}</span></code></pre><h5>GC_TEST(NeedStack, NeedHeap, Live)</h5><p><code class="inline">$GC_TEST(NeedStack, NeedHeap, Live)</code> tests that given amount of
│ │ │  stack space and heap space is available.  If not it will do a
│ │ │ -garbage collection.  Typical use:</p><pre><code class="makeup erlang" translate="no"><span class="nf">test_heap</span><span class="p" data-group-id="7509089151-1">(</span><span class="n">Nh</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p" data-group-id="7509089151-1">)</span><span class="w"> </span><span class="p" data-group-id="7509089151-2">{</span><span class="w">
│ │ │ -    </span><span class="sc">$G</span><span class="n">C_TEST</span><span class="p" data-group-id="7509089151-3">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="sc">$N</span><span class="ss">h</span><span class="p">,</span><span class="w"> </span><span class="sc">$L</span><span class="ss">ive</span><span class="p" data-group-id="7509089151-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7509089151-2">}</span></code></pre><h5>AH(NeedStack, NeedHeap, Live)</h5><p><code class="inline">AH(NeedStack, NeedHeap, Live)</code> allocates a stack frame and
│ │ │ +garbage collection.  Typical use:</p><pre><code class="makeup erlang" translate="no"><span class="nf">test_heap</span><span class="p" data-group-id="8826536719-1">(</span><span class="n">Nh</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p" data-group-id="8826536719-1">)</span><span class="w"> </span><span class="p" data-group-id="8826536719-2">{</span><span class="w">
│ │ │ +    </span><span class="sc">$G</span><span class="n">C_TEST</span><span class="p" data-group-id="8826536719-3">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="sc">$N</span><span class="ss">h</span><span class="p">,</span><span class="w"> </span><span class="sc">$L</span><span class="ss">ive</span><span class="p" data-group-id="8826536719-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8826536719-2">}</span></code></pre><h5>AH(NeedStack, NeedHeap, Live)</h5><p><code class="inline">AH(NeedStack, NeedHeap, Live)</code> allocates a stack frame and
│ │ │  optionally additional heap space.</p><h4>Pre-defined macros and variables</h4><p><strong>beam_makeops</strong> defines several built-in macros and pre-bound variables.</p><h5>The NEXT_INSTRUCTION pre-bound variable</h5><p>The NEXT_INSTRUCTION is a pre-bound variable that is available in
│ │ │ -all instructions.  It expands to the address of the next instruction.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">i_call</span><span class="p" data-group-id="0984118111-1">(</span><span class="n">CallDest</span><span class="p" data-group-id="0984118111-1">)</span><span class="w"> </span><span class="p" data-group-id="0984118111-2">{</span><span class="w">
│ │ │ +all instructions.  It expands to the address of the next instruction.</p><p>Here is an example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">i_call</span><span class="p" data-group-id="0120380468-1">(</span><span class="n">CallDest</span><span class="p" data-group-id="0120380468-1">)</span><span class="w"> </span><span class="p" data-group-id="0120380468-2">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="p">|</span><span class="w"> </span><span class="o">-</span><span class="ss">no_next</span><span class="w">
│ │ │ -    </span><span class="sc">$S</span><span class="n">AVE_CONTINUATION_POINTER</span><span class="p" data-group-id="0984118111-3">(</span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="p" data-group-id="0984118111-3">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="sc">$D</span><span class="n">ISPATCH_REL</span><span class="p" data-group-id="0984118111-4">(</span><span class="sc">$C</span><span class="ss">allDest</span><span class="p" data-group-id="0984118111-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0984118111-2">}</span></code></pre><p>When calling a function, the return address is first stored in <code class="inline">E[0]</code>
│ │ │ +    </span><span class="sc">$S</span><span class="n">AVE_CONTINUATION_POINTER</span><span class="p" data-group-id="0120380468-3">(</span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="p" data-group-id="0120380468-3">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="sc">$D</span><span class="n">ISPATCH_REL</span><span class="p" data-group-id="0120380468-4">(</span><span class="sc">$C</span><span class="ss">allDest</span><span class="p" data-group-id="0120380468-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0120380468-2">}</span></code></pre><p>When calling a function, the return address is first stored in <code class="inline">E[0]</code>
│ │ │  (using the <code class="inline">$SAVE_CONTINUATION_POINTER()</code> macro), and then control is
│ │ │ -transferred to the callee.  Here is the generated code:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="9993846443-1">(</span><span class="ss">i_call_f</span><span class="p" data-group-id="9993846443-1">)</span><span class="p">:</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9993846443-2">{</span><span class="w">
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="9993846443-3">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="9993846443-4">(</span><span class="o">*</span><span class="p" data-group-id="9993846443-5">(</span><span class="n">I</span><span class="o">+</span><span class="mi">2</span><span class="p" data-group-id="9993846443-5">)</span><span class="p" data-group-id="9993846443-4">)</span><span class="p" data-group-id="9993846443-3">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="o">*</span><span class="n">E</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9993846443-6">(</span><span class="n">BeamInstr</span><span class="p" data-group-id="9993846443-6">)</span><span class="w"> </span><span class="p" data-group-id="9993846443-7">(</span><span class="n">I</span><span class="o">+</span><span class="mi">2</span><span class="p" data-group-id="9993846443-7">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │ +transferred to the callee.  Here is the generated code:</p><pre><code class="makeup erlang" translate="no"><span class="n">OpCase</span><span class="p" data-group-id="7100391004-1">(</span><span class="ss">i_call_f</span><span class="p" data-group-id="7100391004-1">)</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7100391004-2">{</span><span class="w">
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="7100391004-3">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="7100391004-4">(</span><span class="o">*</span><span class="p" data-group-id="7100391004-5">(</span><span class="n">I</span><span class="o">+</span><span class="mi">2</span><span class="p" data-group-id="7100391004-5">)</span><span class="p" data-group-id="7100391004-4">)</span><span class="p" data-group-id="7100391004-3">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="o">*</span><span class="n">E</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7100391004-6">(</span><span class="n">BeamInstr</span><span class="p" data-group-id="7100391004-6">)</span><span class="w"> </span><span class="p" data-group-id="7100391004-7">(</span><span class="n">I</span><span class="o">+</span><span class="mi">2</span><span class="p" data-group-id="7100391004-7">)</span><span class="p">;</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │      </span><span class="o">/</span><span class="o">*</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="ss">dispatch</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">intentionally</span><span class="w"> </span><span class="ss">left</span><span class="w"> </span><span class="ss">out</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="o">*</span><span class="o">/</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9993846443-2">}</span></code></pre><p>We can see that that <code class="inline">$NEXT_INSTRUCTION</code> has been expanded to <code class="inline">I+2</code>.
│ │ │ +</span><span class="p" data-group-id="7100391004-2">}</span></code></pre><p>We can see that that <code class="inline">$NEXT_INSTRUCTION</code> has been expanded to <code class="inline">I+2</code>.
│ │ │  That makes sense since the size of the <code class="inline">i_call_f/1</code> instruction is
│ │ │  two words.</p><h5>The IP_ADJUSTMENT pre-bound variable</h5><p><code class="inline">$IP_ADJUSTMENT</code> is usually 0.  In a few combined instructions
│ │ │  (described below) it can be non-zero.  It is used like this
│ │ │ -in <code class="inline">macros.tab</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">SET_I_REL</span><span class="p" data-group-id="5333437962-1">(</span><span class="n">Offset</span><span class="p" data-group-id="5333437962-1">)</span><span class="w"> </span><span class="p" data-group-id="5333437962-2">{</span><span class="w">
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="5333437962-3">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="5333437962-4">(</span><span class="o">*</span><span class="p" data-group-id="5333437962-5">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="5333437962-6">(</span><span class="sc">$O</span><span class="ss">ffset</span><span class="p" data-group-id="5333437962-6">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="sc">$I</span><span class="n">P_ADJUSTMENT</span><span class="p" data-group-id="5333437962-5">)</span><span class="p" data-group-id="5333437962-4">)</span><span class="p" data-group-id="5333437962-3">)</span><span class="p">;</span><span class="w">
│ │ │ +in <code class="inline">macros.tab</code>:</p><pre><code class="makeup erlang" translate="no"><span class="n">SET_I_REL</span><span class="p" data-group-id="4663170900-1">(</span><span class="n">Offset</span><span class="p" data-group-id="4663170900-1">)</span><span class="w"> </span><span class="p" data-group-id="4663170900-2">{</span><span class="w">
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="4663170900-3">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="4663170900-4">(</span><span class="o">*</span><span class="p" data-group-id="4663170900-5">(</span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="4663170900-6">(</span><span class="sc">$O</span><span class="ss">ffset</span><span class="p" data-group-id="4663170900-6">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="sc">$I</span><span class="n">P_ADJUSTMENT</span><span class="p" data-group-id="4663170900-5">)</span><span class="p" data-group-id="4663170900-4">)</span><span class="p" data-group-id="4663170900-3">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="sc">$O</span><span class="ss">ffset</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="sc">$I</span><span class="n">P_ADJUSTMENT</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5333437962-2">}</span></code></pre><p>Avoid using <code class="inline">IP_ADJUSTMENT</code> directly.  Use <code class="inline">SET_I_REL()</code> or
│ │ │ +</span><span class="p" data-group-id="4663170900-2">}</span></code></pre><p>Avoid using <code class="inline">IP_ADJUSTMENT</code> directly.  Use <code class="inline">SET_I_REL()</code> or
│ │ │  one of the macros that invoke such as <code class="inline">FAIL()</code> or <code class="inline">JUMP()</code>
│ │ │  defined in <code class="inline">macros.tab</code>.</p><h4>Pre-defined macro functions</h4><h5>The IF() macro</h5><p><code class="inline">$IF(Expr, IfTrue, IfFalse)</code> evaluates <code class="inline">Expr</code>, which must be a valid
│ │ │  Perl expression (which for simple numeric expressions have the same
│ │ │  syntax as C).  If <code class="inline">Expr</code> evaluates to 0, the entire <code class="inline">IF()</code> expression will be
│ │ │  replaced with <code class="inline">IfFalse</code>, otherwise it will be replaced with <code class="inline">IfTrue</code>.</p><p>See the description of <code class="inline">OPERAND_POSITION()</code> for an example.</p><h5>The OPERAND_POSITION() macro</h5><p><code class="inline">$OPERAND_POSITION(Expr)</code> returns the position for <code class="inline">Expr</code>, if
│ │ │  <code class="inline">Expr</code> is an operand that is not packed.  The first operand is
│ │ │ -at position 1.</p><p>Returns 0 otherwise.</p><p>This macro could be used like this in order to share code:</p><pre><code class="makeup erlang" translate="no"><span class="n">FAIL</span><span class="p" data-group-id="7771664600-1">(</span><span class="n">Fail</span><span class="p" data-group-id="7771664600-1">)</span><span class="w"> </span><span class="p" data-group-id="7771664600-2">{</span><span class="w">
│ │ │ +at position 1.</p><p>Returns 0 otherwise.</p><p>This macro could be used like this in order to share code:</p><pre><code class="makeup erlang" translate="no"><span class="n">FAIL</span><span class="p" data-group-id="5322578681-1">(</span><span class="n">Fail</span><span class="p" data-group-id="5322578681-1">)</span><span class="w"> </span><span class="p" data-group-id="5322578681-2">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="p">|</span><span class="w"> </span><span class="o">-</span><span class="ss">no_prefetch</span><span class="w">
│ │ │ -    </span><span class="sc">$I</span><span class="n">F</span><span class="p" data-group-id="7771664600-3">(</span><span class="sc">$O</span><span class="n">PERAND_POSITION</span><span class="p" data-group-id="7771664600-4">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="7771664600-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">&amp;&amp;</span><span class="w"> </span><span class="sc">$I</span><span class="n">P_ADJUSTMENT</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="sc">$I</span><span class="n">F</span><span class="p" data-group-id="5322578681-3">(</span><span class="sc">$O</span><span class="n">PERAND_POSITION</span><span class="p" data-group-id="5322578681-4">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="5322578681-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="p">&amp;&amp;</span><span class="w"> </span><span class="sc">$I</span><span class="n">P_ADJUSTMENT</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │          </span><span class="ss">goto</span><span class="w"> </span><span class="ss">common_jump</span><span class="p">,</span><span class="w">
│ │ │ -        </span><span class="sc">$D</span><span class="n">O_JUMP</span><span class="p" data-group-id="7771664600-5">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="7771664600-5">)</span><span class="p" data-group-id="7771664600-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7771664600-2">}</span><span class="w">
│ │ │ +        </span><span class="sc">$D</span><span class="n">O_JUMP</span><span class="p" data-group-id="5322578681-5">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="5322578681-5">)</span><span class="p" data-group-id="5322578681-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5322578681-2">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">DO_JUMP</span><span class="p" data-group-id="7771664600-6">(</span><span class="n">Fail</span><span class="p" data-group-id="7771664600-6">)</span><span class="w"> </span><span class="p" data-group-id="7771664600-7">{</span><span class="w">
│ │ │ -    </span><span class="sc">$S</span><span class="n">ET_I_REL</span><span class="p" data-group-id="7771664600-8">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="7771664600-8">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">Goto</span><span class="p" data-group-id="7771664600-9">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="7771664600-9">)</span><span class="p">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7771664600-7">}</span><span class="w">
│ │ │ +</span><span class="n">DO_JUMP</span><span class="p" data-group-id="5322578681-6">(</span><span class="n">Fail</span><span class="p" data-group-id="5322578681-6">)</span><span class="w"> </span><span class="p" data-group-id="5322578681-7">{</span><span class="w">
│ │ │ +    </span><span class="sc">$S</span><span class="n">ET_I_REL</span><span class="p" data-group-id="5322578681-8">(</span><span class="sc">$F</span><span class="ss">ail</span><span class="p" data-group-id="5322578681-8">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">Goto</span><span class="p" data-group-id="5322578681-9">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="5322578681-9">)</span><span class="p">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5322578681-7">}</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="ss">beam_emu</span><span class="p">.</span><span class="nc">c</span><span class="p">:</span><span class="w">
│ │ │  </span><span class="nc">common_jump</span><span class="p">:</span><span class="w">
│ │ │ -   </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="7771664600-10">[</span><span class="mi">1</span><span class="p" data-group-id="7771664600-10">]</span><span class="p">;</span><span class="w">
│ │ │ -   </span><span class="n">Goto</span><span class="p" data-group-id="7771664600-11">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="7771664600-11">)</span><span class="p">)</span><span class="p">;</span></code></pre><h4>The $REFRESH_GEN_DEST() macro</h4><p>When a specific instruction has a <code class="inline">d</code> operand, early during execution
│ │ │ +   </span><span class="n">I</span><span class="w"> </span><span class="o">+</span><span class="o">=</span><span class="w"> </span><span class="n">I</span><span class="p" data-group-id="5322578681-10">[</span><span class="mi">1</span><span class="p" data-group-id="5322578681-10">]</span><span class="p">;</span><span class="w">
│ │ │ +   </span><span class="n">Goto</span><span class="p" data-group-id="5322578681-11">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="5322578681-11">)</span><span class="p">)</span><span class="p">;</span></code></pre><h4>The $REFRESH_GEN_DEST() macro</h4><p>When a specific instruction has a <code class="inline">d</code> operand, early during execution
│ │ │  of the instruction, a pointer will be initialized to point to the X or
│ │ │  Y register in question.</p><p>If there is a garbage collection before the result is stored,
│ │ │  the stack will move and if the <code class="inline">d</code> operand referred to a Y
│ │ │  register, the pointer will no longer be valid.  (Y registers are
│ │ │  stored on the stack.)</p><p>In those circumstances, <code class="inline">$REFRESH_GEN_DEST()</code> must be invoked
│ │ │  to set up the pointer again. <strong>beam_makeops</strong> will notice
│ │ │  if there is a call to a function that does a garbage collection and
│ │ │  <code class="inline">$REFRESH_GEN_DEST()</code> is not called.</p><p>Here is a complete example.  The <code class="inline">new_map</code> instruction is defined
│ │ │ -like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">new_map</span><span class="w"> </span><span class="ss">d</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="n">I</span></code></pre><p>It is implemented like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">new_map</span><span class="p" data-group-id="5279414772-1">(</span><span class="n">Dst</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p" data-group-id="5279414772-1">)</span><span class="w"> </span><span class="p" data-group-id="5279414772-2">{</span><span class="w">
│ │ │ +like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">new_map</span><span class="w"> </span><span class="ss">d</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="n">I</span></code></pre><p>It is implemented like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">new_map</span><span class="p" data-group-id="4070597240-1">(</span><span class="n">Dst</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p" data-group-id="4070597240-1">)</span><span class="w"> </span><span class="p" data-group-id="4070597240-2">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">res</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │      </span><span class="n">HEAVY_SWAPOUT</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_gc_new_map</span><span class="p" data-group-id="5279414772-3">(</span><span class="ss">c_p</span><span class="p">,</span><span class="w"> </span><span class="ss">reg</span><span class="p">,</span><span class="w"> </span><span class="sc">$L</span><span class="ss">ive</span><span class="p">,</span><span class="w"> </span><span class="sc">$N</span><span class="p">,</span><span class="w"> </span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="p" data-group-id="5279414772-3">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_gc_new_map</span><span class="p" data-group-id="4070597240-3">(</span><span class="ss">c_p</span><span class="p">,</span><span class="w"> </span><span class="ss">reg</span><span class="p">,</span><span class="w"> </span><span class="sc">$L</span><span class="ss">ive</span><span class="p">,</span><span class="w"> </span><span class="sc">$N</span><span class="p">,</span><span class="w"> </span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="p" data-group-id="4070597240-3">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">HEAVY_SWAPIN</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="5279414772-4">(</span><span class="p" data-group-id="5279414772-4">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="4070597240-4">(</span><span class="p" data-group-id="4070597240-4">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">res</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="sc">$N</span><span class="n">EXT</span><span class="p" data-group-id="5279414772-5">(</span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="o">+</span><span class="sc">$N</span><span class="p" data-group-id="5279414772-5">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5279414772-2">}</span></code></pre><p>If we have forgotten the <code class="inline">$REFRESH_GEN_DEST()</code> there would be a message
│ │ │ -similar to this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">pointer</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">destination</span><span class="w"> </span><span class="nb">register</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">invalid</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="n">GC</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="ss">use</span><span class="w"> </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="4098187314-1">(</span><span class="p" data-group-id="4098187314-1">)</span><span class="w">
│ │ │ -</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">body</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="ss">new_map</span><span class="w"> </span><span class="ss">at</span><span class="w"> </span><span class="ss">beam</span><span class="o">/</span><span class="ss">map_instrs</span><span class="p">.</span><span class="nf">tab</span><span class="p" data-group-id="4098187314-2">(</span><span class="mi">30</span><span class="p" data-group-id="4098187314-2">)</span></code></pre><h4>Variable number of operands</h4><p>Here follows an example of how to handle an instruction with a variable number
│ │ │ +    </span><span class="sc">$N</span><span class="n">EXT</span><span class="p" data-group-id="4070597240-5">(</span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="o">+</span><span class="sc">$N</span><span class="p" data-group-id="4070597240-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4070597240-2">}</span></code></pre><p>If we have forgotten the <code class="inline">$REFRESH_GEN_DEST()</code> there would be a message
│ │ │ +similar to this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">pointer</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">destination</span><span class="w"> </span><span class="nb">register</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">invalid</span><span class="w"> </span><span class="k">after</span><span class="w"> </span><span class="n">GC</span><span class="w"> </span><span class="o">--</span><span class="w"> </span><span class="ss">use</span><span class="w"> </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="4723259740-1">(</span><span class="p" data-group-id="4723259740-1">)</span><span class="w">
│ │ │ +</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">body</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="ss">new_map</span><span class="w"> </span><span class="ss">at</span><span class="w"> </span><span class="ss">beam</span><span class="o">/</span><span class="ss">map_instrs</span><span class="p">.</span><span class="nf">tab</span><span class="p" data-group-id="4723259740-2">(</span><span class="mi">30</span><span class="p" data-group-id="4723259740-2">)</span></code></pre><h4>Variable number of operands</h4><p>Here follows an example of how to handle an instruction with a variable number
│ │ │  of operands for the interpreter.  Here is the instruction definition in <code class="inline">emu/ops.tab</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">put_tuple2</span><span class="w"> </span><span class="ss">xy</span><span class="w"> </span><span class="n">I</span><span class="w"> </span><span class="o">*</span></code></pre><p>For the interpreter, the <code class="inline">*</code> is optional, because it does not effect code generation
│ │ │  in any way. However, it is recommended to include it to make it clear for human readers
│ │ │  that there is a variable number of operands.</p><p>Use the <code class="inline">$NEXT_INSTRUCTION</code> macro to obtain a pointer to the first of the variable
│ │ │ -operands.</p><p>Here is the implementation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">put_tuple2</span><span class="p" data-group-id="3147946467-1">(</span><span class="n">Dst</span><span class="p">,</span><span class="w"> </span><span class="n">Arity</span><span class="p" data-group-id="3147946467-1">)</span><span class="w"> </span><span class="p" data-group-id="3147946467-2">{</span><span class="w">
│ │ │ +operands.</p><p>Here is the implementation:</p><pre><code class="makeup erlang" translate="no"><span class="nf">put_tuple2</span><span class="p" data-group-id="1796358249-1">(</span><span class="n">Dst</span><span class="p">,</span><span class="w"> </span><span class="n">Arity</span><span class="p" data-group-id="1796358249-1">)</span><span class="w"> </span><span class="p" data-group-id="1796358249-2">{</span><span class="w">
│ │ │  </span><span class="n">Eterm</span><span class="o">*</span><span class="w"> </span><span class="ss">hp</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">HTOP</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">arity</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$A</span><span class="ss">rity</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="n">Eterm</span><span class="o">*</span><span class="w"> </span><span class="ss">dst_ptr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="err">&amp;</span><span class="p" data-group-id="3147946467-3">(</span><span class="sc">$D</span><span class="ss">st</span><span class="p" data-group-id="3147946467-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="n">Eterm</span><span class="o">*</span><span class="w"> </span><span class="ss">dst_ptr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="err">&amp;</span><span class="p" data-group-id="1796358249-3">(</span><span class="sc">$D</span><span class="ss">st</span><span class="p" data-group-id="1796358249-3">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">/</span><span class="p">|</span><span class="w"> </span><span class="o">-</span><span class="ss">no_next</span><span class="w">
│ │ │ -</span><span class="n">ASSERT</span><span class="p" data-group-id="3147946467-4">(</span><span class="ss">arity</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3147946467-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="ss">hp</span><span class="o">++</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_arityval</span><span class="p" data-group-id="3147946467-5">(</span><span class="ss">arity</span><span class="p" data-group-id="3147946467-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="n">ASSERT</span><span class="p" data-group-id="1796358249-4">(</span><span class="ss">arity</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="1796358249-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="ss">hp</span><span class="o">++</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_arityval</span><span class="p" data-group-id="1796358249-5">(</span><span class="ss">arity</span><span class="p" data-group-id="1796358249-5">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">*</span><span class="w">
│ │ │   </span><span class="o">*</span><span class="w"> </span><span class="n">The</span><span class="w"> </span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="w"> </span><span class="ss">macro</span><span class="w"> </span><span class="ss">points</span><span class="w"> </span><span class="ss">just</span><span class="w"> </span><span class="ss">beyond</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">fixed</span><span class="w">
│ │ │   </span><span class="o">*</span><span class="w"> </span><span class="ss">operands</span><span class="p">.</span><span class="w"> </span><span class="n">In</span><span class="w"> </span><span class="ss">this</span><span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="ss">it</span><span class="w"> </span><span class="ss">points</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">descriptor</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │   </span><span class="o">*</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">first</span><span class="w"> </span><span class="nb">element</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">be</span><span class="w"> </span><span class="nb">put</span><span class="w"> </span><span class="ss">into</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">tuple</span><span class="p">.</span><span class="w">
│ │ │   </span><span class="o">*</span><span class="o">/</span><span class="w">
│ │ │  </span><span class="n">I</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$N</span><span class="n">EXT_INSTRUCTION</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="ss">do</span><span class="w"> </span><span class="p" data-group-id="3147946467-6">{</span><span class="w">
│ │ │ +</span><span class="ss">do</span><span class="w"> </span><span class="p" data-group-id="1796358249-6">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">term</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">*</span><span class="n">I</span><span class="o">++</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nf">switch</span><span class="w"> </span><span class="p" data-group-id="3147946467-7">(</span><span class="nf">loader_tag</span><span class="p" data-group-id="3147946467-8">(</span><span class="ss">term</span><span class="p" data-group-id="3147946467-8">)</span><span class="p" data-group-id="3147946467-7">)</span><span class="w"> </span><span class="p" data-group-id="3147946467-9">{</span><span class="w">
│ │ │ +    </span><span class="nf">switch</span><span class="w"> </span><span class="p" data-group-id="1796358249-7">(</span><span class="nf">loader_tag</span><span class="p" data-group-id="1796358249-8">(</span><span class="ss">term</span><span class="p" data-group-id="1796358249-8">)</span><span class="p" data-group-id="1796358249-7">)</span><span class="w"> </span><span class="p" data-group-id="1796358249-9">{</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">LOADER_X_REG</span><span class="p">:</span><span class="w">
│ │ │ -    </span><span class="o">*</span><span class="ss">hp</span><span class="o">++</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">x</span><span class="p" data-group-id="3147946467-10">(</span><span class="nf">loader_x_reg_index</span><span class="p" data-group-id="3147946467-11">(</span><span class="ss">term</span><span class="p" data-group-id="3147946467-11">)</span><span class="p" data-group-id="3147946467-10">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="o">*</span><span class="ss">hp</span><span class="o">++</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">x</span><span class="p" data-group-id="1796358249-10">(</span><span class="nf">loader_x_reg_index</span><span class="p" data-group-id="1796358249-11">(</span><span class="ss">term</span><span class="p" data-group-id="1796358249-11">)</span><span class="p" data-group-id="1796358249-10">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">break</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="k">case</span><span class="w"> </span><span class="n">LOADER_Y_REG</span><span class="p">:</span><span class="w">
│ │ │ -    </span><span class="o">*</span><span class="ss">hp</span><span class="o">++</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">y</span><span class="p" data-group-id="3147946467-12">(</span><span class="nf">loader_y_reg_index</span><span class="p" data-group-id="3147946467-13">(</span><span class="ss">term</span><span class="p" data-group-id="3147946467-13">)</span><span class="p" data-group-id="3147946467-12">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="o">*</span><span class="ss">hp</span><span class="o">++</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">y</span><span class="p" data-group-id="1796358249-12">(</span><span class="nf">loader_y_reg_index</span><span class="p" data-group-id="1796358249-13">(</span><span class="ss">term</span><span class="p" data-group-id="1796358249-13">)</span><span class="p" data-group-id="1796358249-12">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">break</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="nc">default</span><span class="p">:</span><span class="w">
│ │ │      </span><span class="o">*</span><span class="ss">hp</span><span class="o">++</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">term</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">break</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="3147946467-9">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3147946467-6">}</span><span class="w"> </span><span class="nf">while</span><span class="w"> </span><span class="p" data-group-id="3147946467-14">(</span><span class="o">--</span><span class="ss">arity</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="3147946467-14">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="o">*</span><span class="ss">dst_ptr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_tuple</span><span class="p" data-group-id="3147946467-15">(</span><span class="n">HTOP</span><span class="p" data-group-id="3147946467-15">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1796358249-9">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1796358249-6">}</span><span class="w"> </span><span class="nf">while</span><span class="w"> </span><span class="p" data-group-id="1796358249-14">(</span><span class="o">--</span><span class="ss">arity</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="1796358249-14">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="o">*</span><span class="ss">dst_ptr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_tuple</span><span class="p" data-group-id="1796358249-15">(</span><span class="n">HTOP</span><span class="p" data-group-id="1796358249-15">)</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="n">HTOP</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">hp</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="n">ASSERT</span><span class="p" data-group-id="3147946467-16">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="3147946467-17">(</span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="3147946467-18">(</span><span class="n">Eterm</span><span class="w"> </span><span class="o">*</span><span class="p" data-group-id="3147946467-18">)</span><span class="n">I</span><span class="p" data-group-id="3147946467-17">)</span><span class="p" data-group-id="3147946467-16">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="n">Goto</span><span class="p" data-group-id="3147946467-19">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="3147946467-19">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3147946467-2">}</span></code></pre><h4>Combined instructions</h4><p><strong>Problem</strong>: For frequently executed instructions we want to use
│ │ │ +</span><span class="n">ASSERT</span><span class="p" data-group-id="1796358249-16">(</span><span class="n">VALID_INSTR</span><span class="p" data-group-id="1796358249-17">(</span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="1796358249-18">(</span><span class="n">Eterm</span><span class="w"> </span><span class="o">*</span><span class="p" data-group-id="1796358249-18">)</span><span class="n">I</span><span class="p" data-group-id="1796358249-17">)</span><span class="p" data-group-id="1796358249-16">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="n">Goto</span><span class="p" data-group-id="1796358249-19">(</span><span class="o">*</span><span class="n">I</span><span class="p" data-group-id="1796358249-19">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1796358249-2">}</span></code></pre><h4>Combined instructions</h4><p><strong>Problem</strong>: For frequently executed instructions we want to use
│ │ │  &quot;fast&quot; operands types such as <code class="inline">x</code> and <code class="inline">y</code>, as opposed to <code class="inline">s</code> or <code class="inline">S</code>.
│ │ │  To avoid an explosion in code size, we want to share most of the
│ │ │  implementation between the instructions.  Here are the specific
│ │ │  instructions for <code class="inline">i_increment/5</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_increment</span><span class="w"> </span><span class="ss">r</span><span class="w"> </span><span class="n">W</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span><span class="w">
│ │ │  </span><span class="ss">i_increment</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="n">W</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span><span class="w">
│ │ │ -</span><span class="ss">i_increment</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="n">W</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span></code></pre><p>The <code class="inline">i_increment</code> instruction is implemented like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">i_increment</span><span class="p" data-group-id="1929826416-1">(</span><span class="n">Source</span><span class="p">,</span><span class="w"> </span><span class="n">IncrementVal</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="1929826416-1">)</span><span class="w"> </span><span class="p" data-group-id="1929826416-2">{</span><span class="w">
│ │ │ +</span><span class="ss">i_increment</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="n">W</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span></code></pre><p>The <code class="inline">i_increment</code> instruction is implemented like this:</p><pre><code class="makeup erlang" translate="no"><span class="nf">i_increment</span><span class="p" data-group-id="9290250416-1">(</span><span class="n">Source</span><span class="p">,</span><span class="w"> </span><span class="n">IncrementVal</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="9290250416-1">)</span><span class="w"> </span><span class="p" data-group-id="9290250416-2">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">increment_reg_source</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">ource</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">increment_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$I</span><span class="ss">ncrementVal</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Uint</span><span class="w"> </span><span class="ss">live</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">result</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="1929826416-3">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="1929826416-4">(</span><span class="nf">is_small</span><span class="p" data-group-id="1929826416-5">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="1929826416-5">)</span><span class="p" data-group-id="1929826416-4">)</span><span class="p" data-group-id="1929826416-3">)</span><span class="w"> </span><span class="p" data-group-id="1929826416-6">{</span><span class="w">
│ │ │ -        </span><span class="n">Sint</span><span class="w"> </span><span class="ss">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">signed_val</span><span class="p" data-group-id="1929826416-7">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="1929826416-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">increment_val</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="1929826416-8">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="1929826416-9">(</span><span class="n">IS_SSMALL</span><span class="p" data-group-id="1929826416-10">(</span><span class="ss">i</span><span class="p" data-group-id="1929826416-10">)</span><span class="p" data-group-id="1929826416-9">)</span><span class="p" data-group-id="1929826416-8">)</span><span class="w"> </span><span class="p" data-group-id="1929826416-11">{</span><span class="w">
│ │ │ -            </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="1929826416-12">(</span><span class="ss">i</span><span class="p" data-group-id="1929826416-12">)</span><span class="p">;</span><span class="w">
│ │ │ -            </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="1929826416-13">(</span><span class="p" data-group-id="1929826416-13">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="1929826416-11">}</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1929826416-6">}</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="9290250416-3">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="9290250416-4">(</span><span class="nf">is_small</span><span class="p" data-group-id="9290250416-5">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="9290250416-5">)</span><span class="p" data-group-id="9290250416-4">)</span><span class="p" data-group-id="9290250416-3">)</span><span class="w"> </span><span class="p" data-group-id="9290250416-6">{</span><span class="w">
│ │ │ +        </span><span class="n">Sint</span><span class="w"> </span><span class="ss">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">signed_val</span><span class="p" data-group-id="9290250416-7">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="9290250416-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">increment_val</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="9290250416-8">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="9290250416-9">(</span><span class="n">IS_SSMALL</span><span class="p" data-group-id="9290250416-10">(</span><span class="ss">i</span><span class="p" data-group-id="9290250416-10">)</span><span class="p" data-group-id="9290250416-9">)</span><span class="p" data-group-id="9290250416-8">)</span><span class="w"> </span><span class="p" data-group-id="9290250416-11">{</span><span class="w">
│ │ │ +            </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="9290250416-12">(</span><span class="ss">i</span><span class="p" data-group-id="9290250416-12">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="9290250416-13">(</span><span class="p" data-group-id="9290250416-13">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9290250416-11">}</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9290250416-6">}</span><span class="w">
│ │ │      </span><span class="ss">live</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$L</span><span class="ss">ive</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">HEAVY_SWAPOUT</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">reg</span><span class="p" data-group-id="1929826416-14">[</span><span class="ss">live</span><span class="p" data-group-id="1929826416-14">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">increment_reg_val</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">reg</span><span class="p" data-group-id="1929826416-15">[</span><span class="ss">live</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="1929826416-15">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="1929826416-16">(</span><span class="ss">increment_val</span><span class="p" data-group-id="1929826416-16">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_gc_mixed_plus</span><span class="p" data-group-id="1929826416-17">(</span><span class="ss">c_p</span><span class="p">,</span><span class="w"> </span><span class="ss">reg</span><span class="p">,</span><span class="w"> </span><span class="ss">live</span><span class="p" data-group-id="1929826416-17">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">reg</span><span class="p" data-group-id="9290250416-14">[</span><span class="ss">live</span><span class="p" data-group-id="9290250416-14">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">increment_reg_val</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">reg</span><span class="p" data-group-id="9290250416-15">[</span><span class="ss">live</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="9290250416-15">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="9290250416-16">(</span><span class="ss">increment_val</span><span class="p" data-group-id="9290250416-16">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_gc_mixed_plus</span><span class="p" data-group-id="9290250416-17">(</span><span class="ss">c_p</span><span class="p">,</span><span class="w"> </span><span class="ss">reg</span><span class="p">,</span><span class="w"> </span><span class="ss">live</span><span class="p" data-group-id="9290250416-17">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">HEAVY_SWAPIN</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">ERTS_HOLE_CHECK</span><span class="p" data-group-id="1929826416-18">(</span><span class="ss">c_p</span><span class="p" data-group-id="1929826416-18">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="1929826416-19">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="1929826416-20">(</span><span class="nf">is_value</span><span class="p" data-group-id="1929826416-21">(</span><span class="ss">result</span><span class="p" data-group-id="1929826416-21">)</span><span class="p" data-group-id="1929826416-20">)</span><span class="p" data-group-id="1929826416-19">)</span><span class="w"> </span><span class="p" data-group-id="1929826416-22">{</span><span class="w">
│ │ │ -        </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="1929826416-23">(</span><span class="p" data-group-id="1929826416-23">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">ERTS_HOLE_CHECK</span><span class="p" data-group-id="9290250416-18">(</span><span class="ss">c_p</span><span class="p" data-group-id="9290250416-18">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="9290250416-19">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="9290250416-20">(</span><span class="nf">is_value</span><span class="p" data-group-id="9290250416-21">(</span><span class="ss">result</span><span class="p" data-group-id="9290250416-21">)</span><span class="p" data-group-id="9290250416-20">)</span><span class="p" data-group-id="9290250416-19">)</span><span class="w"> </span><span class="p" data-group-id="9290250416-22">{</span><span class="w">
│ │ │ +        </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="9290250416-23">(</span><span class="p" data-group-id="9290250416-23">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">result</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="1929826416-24">(</span><span class="p" data-group-id="1929826416-24">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="1929826416-22">}</span><span class="w">
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="1929826416-25">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">freason</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="n">BADMATCH</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_value</span><span class="p" data-group-id="1929826416-26">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">fvalue</span><span class="p" data-group-id="1929826416-26">)</span><span class="p" data-group-id="1929826416-25">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="9290250416-24">(</span><span class="p" data-group-id="9290250416-24">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="9290250416-22">}</span><span class="w">
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="9290250416-25">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">freason</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="n">BADMATCH</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_value</span><span class="p" data-group-id="9290250416-26">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">fvalue</span><span class="p" data-group-id="9290250416-26">)</span><span class="p" data-group-id="9290250416-25">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">goto</span><span class="w"> </span><span class="ss">find_func_info</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1929826416-2">}</span></code></pre><p>There will be three almost identical copies of the code.  Given the
│ │ │ +</span><span class="p" data-group-id="9290250416-2">}</span></code></pre><p>There will be three almost identical copies of the code.  Given the
│ │ │  size of the code, that could be too high cost to pay.</p><p>To avoid the three copies of the code, we could use only one specific
│ │ │  instruction:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_increment</span><span class="w"> </span><span class="n">S</span><span class="w"> </span><span class="n">W</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span></code></pre><p>(The same implementation as above will work.)</p><p>That reduces the code size, but is slower because <code class="inline">S</code> means that
│ │ │  there will be extra code to test whether the operand refers to an X
│ │ │  register or a Y register.</p><p><strong>Solution</strong>: We can use &quot;combined instructions&quot;.  Combined
│ │ │  instructions are combined from instruction fragments.  The
│ │ │  bulk of the code can be shared.</p><p>Here we will show how <code class="inline">i_increment</code> can be implemented as a combined
│ │ │  instruction.  We will show each individual fragment first, and then
│ │ │  show how to connect them together.  First we will need a variable that
│ │ │ -we can store the value fetched from the register in:</p><pre><code class="makeup erlang" translate="no"><span class="ss">increment</span><span class="p">.</span><span class="nf">head</span><span class="p" data-group-id="0642928714-1">(</span><span class="p" data-group-id="0642928714-1">)</span><span class="w"> </span><span class="p" data-group-id="0642928714-2">{</span><span class="w">
│ │ │ +we can store the value fetched from the register in:</p><pre><code class="makeup erlang" translate="no"><span class="ss">increment</span><span class="p">.</span><span class="nf">head</span><span class="p" data-group-id="4048977735-1">(</span><span class="p" data-group-id="4048977735-1">)</span><span class="w"> </span><span class="p" data-group-id="4048977735-2">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">increment_reg_val</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0642928714-2">}</span></code></pre><p>The name <code class="inline">increment</code> is the name of the group that the fragment
│ │ │ +</span><span class="p" data-group-id="4048977735-2">}</span></code></pre><p>The name <code class="inline">increment</code> is the name of the group that the fragment
│ │ │  belongs to.  Note that it does not need to have the same
│ │ │  name as the instruction.  The group name is followed by <code class="inline">.</code> and
│ │ │  the name of the fragment.  The name <code class="inline">head</code> is pre-defined.
│ │ │  The code in it will be placed at the beginning of a block, so
│ │ │  that all fragments in the group can access it.</p><p>Next we define the fragment that will pick up the value from the
│ │ │ -register from the first operand:</p><pre><code class="makeup erlang" translate="no"><span class="ss">increment</span><span class="p">.</span><span class="nf">fetch</span><span class="p" data-group-id="1101405808-1">(</span><span class="n">Src</span><span class="p" data-group-id="1101405808-1">)</span><span class="w"> </span><span class="p" data-group-id="1101405808-2">{</span><span class="w">
│ │ │ +register from the first operand:</p><pre><code class="makeup erlang" translate="no"><span class="ss">increment</span><span class="p">.</span><span class="nf">fetch</span><span class="p" data-group-id="1619198977-1">(</span><span class="n">Src</span><span class="p" data-group-id="1619198977-1">)</span><span class="w"> </span><span class="p" data-group-id="1619198977-2">{</span><span class="w">
│ │ │      </span><span class="ss">increment_reg_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1101405808-2">}</span></code></pre><p>We call this fragment <code class="inline">fetch</code>.  This fragment will be duplicated three
│ │ │ -times, one for each value of the first operand (<code class="inline">r</code>, <code class="inline">x</code>, and <code class="inline">y</code>).</p><p>Next we define the main part of the code that do the actual incrementing.</p><pre><code class="makeup erlang" translate="no"><span class="ss">increment</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="0366325390-1">(</span><span class="n">IncrementVal</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="0366325390-1">)</span><span class="w"> </span><span class="p" data-group-id="0366325390-2">{</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1619198977-2">}</span></code></pre><p>We call this fragment <code class="inline">fetch</code>.  This fragment will be duplicated three
│ │ │ +times, one for each value of the first operand (<code class="inline">r</code>, <code class="inline">x</code>, and <code class="inline">y</code>).</p><p>Next we define the main part of the code that do the actual incrementing.</p><pre><code class="makeup erlang" translate="no"><span class="ss">increment</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="6180919361-1">(</span><span class="n">IncrementVal</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="6180919361-1">)</span><span class="w"> </span><span class="p" data-group-id="6180919361-2">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">increment_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$I</span><span class="ss">ncrementVal</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Uint</span><span class="w"> </span><span class="ss">live</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">result</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="0366325390-3">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="0366325390-4">(</span><span class="nf">is_small</span><span class="p" data-group-id="0366325390-5">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="0366325390-5">)</span><span class="p" data-group-id="0366325390-4">)</span><span class="p" data-group-id="0366325390-3">)</span><span class="w"> </span><span class="p" data-group-id="0366325390-6">{</span><span class="w">
│ │ │ -        </span><span class="n">Sint</span><span class="w"> </span><span class="ss">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">signed_val</span><span class="p" data-group-id="0366325390-7">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="0366325390-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">increment_val</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="0366325390-8">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="0366325390-9">(</span><span class="n">IS_SSMALL</span><span class="p" data-group-id="0366325390-10">(</span><span class="ss">i</span><span class="p" data-group-id="0366325390-10">)</span><span class="p" data-group-id="0366325390-9">)</span><span class="p" data-group-id="0366325390-8">)</span><span class="w"> </span><span class="p" data-group-id="0366325390-11">{</span><span class="w">
│ │ │ -            </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="0366325390-12">(</span><span class="ss">i</span><span class="p" data-group-id="0366325390-12">)</span><span class="p">;</span><span class="w">
│ │ │ -            </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="0366325390-13">(</span><span class="p" data-group-id="0366325390-13">)</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0366325390-11">}</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0366325390-6">}</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="6180919361-3">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="6180919361-4">(</span><span class="nf">is_small</span><span class="p" data-group-id="6180919361-5">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="6180919361-5">)</span><span class="p" data-group-id="6180919361-4">)</span><span class="p" data-group-id="6180919361-3">)</span><span class="w"> </span><span class="p" data-group-id="6180919361-6">{</span><span class="w">
│ │ │ +        </span><span class="n">Sint</span><span class="w"> </span><span class="ss">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">signed_val</span><span class="p" data-group-id="6180919361-7">(</span><span class="ss">increment_reg_val</span><span class="p" data-group-id="6180919361-7">)</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">increment_val</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="6180919361-8">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="6180919361-9">(</span><span class="n">IS_SSMALL</span><span class="p" data-group-id="6180919361-10">(</span><span class="ss">i</span><span class="p" data-group-id="6180919361-10">)</span><span class="p" data-group-id="6180919361-9">)</span><span class="p" data-group-id="6180919361-8">)</span><span class="w"> </span><span class="p" data-group-id="6180919361-11">{</span><span class="w">
│ │ │ +            </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="6180919361-12">(</span><span class="ss">i</span><span class="p" data-group-id="6180919361-12">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="6180919361-13">(</span><span class="p" data-group-id="6180919361-13">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="6180919361-11">}</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6180919361-6">}</span><span class="w">
│ │ │      </span><span class="ss">live</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$L</span><span class="ss">ive</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">HEAVY_SWAPOUT</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">reg</span><span class="p" data-group-id="0366325390-14">[</span><span class="ss">live</span><span class="p" data-group-id="0366325390-14">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">increment_reg_val</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">reg</span><span class="p" data-group-id="0366325390-15">[</span><span class="ss">live</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="0366325390-15">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="0366325390-16">(</span><span class="ss">increment_val</span><span class="p" data-group-id="0366325390-16">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_gc_mixed_plus</span><span class="p" data-group-id="0366325390-17">(</span><span class="ss">c_p</span><span class="p">,</span><span class="w"> </span><span class="ss">reg</span><span class="p">,</span><span class="w"> </span><span class="ss">live</span><span class="p" data-group-id="0366325390-17">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">reg</span><span class="p" data-group-id="6180919361-14">[</span><span class="ss">live</span><span class="p" data-group-id="6180919361-14">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">increment_reg_val</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">reg</span><span class="p" data-group-id="6180919361-15">[</span><span class="ss">live</span><span class="o">+</span><span class="mi">1</span><span class="p" data-group-id="6180919361-15">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_small</span><span class="p" data-group-id="6180919361-16">(</span><span class="ss">increment_val</span><span class="p" data-group-id="6180919361-16">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_gc_mixed_plus</span><span class="p" data-group-id="6180919361-17">(</span><span class="ss">c_p</span><span class="p">,</span><span class="w"> </span><span class="ss">reg</span><span class="p">,</span><span class="w"> </span><span class="ss">live</span><span class="p" data-group-id="6180919361-17">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">HEAVY_SWAPIN</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">ERTS_HOLE_CHECK</span><span class="p" data-group-id="0366325390-18">(</span><span class="ss">c_p</span><span class="p" data-group-id="0366325390-18">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="0366325390-19">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="0366325390-20">(</span><span class="nf">is_value</span><span class="p" data-group-id="0366325390-21">(</span><span class="ss">result</span><span class="p" data-group-id="0366325390-21">)</span><span class="p" data-group-id="0366325390-20">)</span><span class="p" data-group-id="0366325390-19">)</span><span class="w"> </span><span class="p" data-group-id="0366325390-22">{</span><span class="w">
│ │ │ -        </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="0366325390-23">(</span><span class="p" data-group-id="0366325390-23">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">ERTS_HOLE_CHECK</span><span class="p" data-group-id="6180919361-18">(</span><span class="ss">c_p</span><span class="p" data-group-id="6180919361-18">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">if</span><span class="w"> </span><span class="p" data-group-id="6180919361-19">(</span><span class="n">ERTS_LIKELY</span><span class="p" data-group-id="6180919361-20">(</span><span class="nf">is_value</span><span class="p" data-group-id="6180919361-21">(</span><span class="ss">result</span><span class="p" data-group-id="6180919361-21">)</span><span class="p" data-group-id="6180919361-20">)</span><span class="p" data-group-id="6180919361-19">)</span><span class="w"> </span><span class="p" data-group-id="6180919361-22">{</span><span class="w">
│ │ │ +        </span><span class="sc">$R</span><span class="n">EFRESH_GEN_DEST</span><span class="p" data-group-id="6180919361-23">(</span><span class="p" data-group-id="6180919361-23">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="sc">$D</span><span class="ss">st</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">result</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="0366325390-24">(</span><span class="p" data-group-id="0366325390-24">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="0366325390-22">}</span><span class="w">
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="0366325390-25">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">freason</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="n">BADMATCH</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_value</span><span class="p" data-group-id="0366325390-26">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">fvalue</span><span class="p" data-group-id="0366325390-26">)</span><span class="p" data-group-id="0366325390-25">)</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="sc">$N</span><span class="n">EXT0</span><span class="p" data-group-id="6180919361-24">(</span><span class="p" data-group-id="6180919361-24">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6180919361-22">}</span><span class="w">
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="6180919361-25">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">freason</span><span class="w"> </span><span class="o">!</span><span class="o">=</span><span class="w"> </span><span class="n">BADMATCH</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="nf">is_value</span><span class="p" data-group-id="6180919361-26">(</span><span class="ss">c_p</span><span class="p">-&gt;</span><span class="ss">fvalue</span><span class="p" data-group-id="6180919361-26">)</span><span class="p" data-group-id="6180919361-25">)</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">goto</span><span class="w"> </span><span class="ss">find_func_info</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0366325390-2">}</span></code></pre><p>We call this fragment <code class="inline">execute</code>.  It will handle the three remaining
│ │ │ +</span><span class="p" data-group-id="6180919361-2">}</span></code></pre><p>We call this fragment <code class="inline">execute</code>.  It will handle the three remaining
│ │ │  operands (<code class="inline">W t d</code>).  There will only be one copy of this fragment.</p><p>Now that we have defined the fragments, we need to inform
│ │ │  <strong>beam_makeops</strong> how they should be connected:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_increment</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">increment</span><span class="p">.</span><span class="ss">fetch</span><span class="p">.</span><span class="ss">execute</span><span class="p">;</span></code></pre><p>To the left of the <code class="inline">:=</code> is the name of the specific instruction that
│ │ │  should be implemented by the fragments, in this case <code class="inline">i_increment</code>.
│ │ │  To the right of <code class="inline">:=</code> is the name of the group with the fragments,
│ │ │  followed by a <code class="inline">.</code>.  Then the name of the fragments in the group are
│ │ │  listed in the order they should be executed.  Note that the <code class="inline">head</code>
│ │ │  fragment is not listed.</p><p>The line ends in <code class="inline">;</code> (to avoid messing up the indentation in Emacs).</p><p>(Note that in practice the <code class="inline">:=</code> line is usually placed before the
│ │ │ -fragments.)</p><p>The generated code looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1137211517-1">{</span><span class="w">
│ │ │ +fragments.)</p><p>The generated code looks like this:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="1336584352-1">{</span><span class="w">
│ │ │    </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">increment_reg_val</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="n">OpCase</span><span class="p" data-group-id="1137211517-2">(</span><span class="ss">i_increment_rWtd</span><span class="p" data-group-id="1137211517-2">)</span><span class="p">:</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="1137211517-3">{</span><span class="w">
│ │ │ -    </span><span class="ss">increment_reg_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">r</span><span class="p" data-group-id="1137211517-4">(</span><span class="mi">0</span><span class="p" data-group-id="1137211517-4">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="1137211517-3">}</span><span class="w">
│ │ │ +  </span><span class="n">OpCase</span><span class="p" data-group-id="1336584352-2">(</span><span class="ss">i_increment_rWtd</span><span class="p" data-group-id="1336584352-2">)</span><span class="p">:</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1336584352-3">{</span><span class="w">
│ │ │ +    </span><span class="ss">increment_reg_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">r</span><span class="p" data-group-id="1336584352-4">(</span><span class="mi">0</span><span class="p" data-group-id="1336584352-4">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1336584352-3">}</span><span class="w">
│ │ │    </span><span class="ss">goto</span><span class="w"> </span><span class="ss">increment__execute</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -  </span><span class="n">OpCase</span><span class="p" data-group-id="1137211517-5">(</span><span class="ss">i_increment_xWtd</span><span class="p" data-group-id="1137211517-5">)</span><span class="p">:</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="1137211517-6">{</span><span class="w">
│ │ │ -    </span><span class="ss">increment_reg_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">xb</span><span class="p" data-group-id="1137211517-7">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="1137211517-8">(</span><span class="n">I</span><span class="p" data-group-id="1137211517-9">[</span><span class="mi">0</span><span class="p" data-group-id="1137211517-9">]</span><span class="p" data-group-id="1137211517-8">)</span><span class="p" data-group-id="1137211517-7">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="1137211517-6">}</span><span class="w">
│ │ │ +  </span><span class="n">OpCase</span><span class="p" data-group-id="1336584352-5">(</span><span class="ss">i_increment_xWtd</span><span class="p" data-group-id="1336584352-5">)</span><span class="p">:</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1336584352-6">{</span><span class="w">
│ │ │ +    </span><span class="ss">increment_reg_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">xb</span><span class="p" data-group-id="1336584352-7">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="1336584352-8">(</span><span class="n">I</span><span class="p" data-group-id="1336584352-9">[</span><span class="mi">0</span><span class="p" data-group-id="1336584352-9">]</span><span class="p" data-group-id="1336584352-8">)</span><span class="p" data-group-id="1336584352-7">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1336584352-6">}</span><span class="w">
│ │ │    </span><span class="ss">goto</span><span class="w"> </span><span class="ss">increment__execute</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -  </span><span class="n">OpCase</span><span class="p" data-group-id="1137211517-10">(</span><span class="ss">i_increment_yWtd</span><span class="p" data-group-id="1137211517-10">)</span><span class="p">:</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="1137211517-11">{</span><span class="w">
│ │ │ -    </span><span class="ss">increment_reg_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">yb</span><span class="p" data-group-id="1137211517-12">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="1137211517-13">(</span><span class="n">I</span><span class="p" data-group-id="1137211517-14">[</span><span class="mi">0</span><span class="p" data-group-id="1137211517-14">]</span><span class="p" data-group-id="1137211517-13">)</span><span class="p" data-group-id="1137211517-12">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="1137211517-11">}</span><span class="w">
│ │ │ +  </span><span class="n">OpCase</span><span class="p" data-group-id="1336584352-10">(</span><span class="ss">i_increment_yWtd</span><span class="p" data-group-id="1336584352-10">)</span><span class="p">:</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1336584352-11">{</span><span class="w">
│ │ │ +    </span><span class="ss">increment_reg_val</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">yb</span><span class="p" data-group-id="1336584352-12">(</span><span class="n">BeamExtraData</span><span class="p" data-group-id="1336584352-13">(</span><span class="n">I</span><span class="p" data-group-id="1336584352-14">[</span><span class="mi">0</span><span class="p" data-group-id="1336584352-14">]</span><span class="p" data-group-id="1336584352-13">)</span><span class="p" data-group-id="1336584352-12">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1336584352-11">}</span><span class="w">
│ │ │    </span><span class="ss">goto</span><span class="w"> </span><span class="ss">increment__execute</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │    </span><span class="nc">increment__execute</span><span class="p">:</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="1137211517-15">{</span><span class="w">
│ │ │ -    </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">Here</span><span class="w"> </span><span class="ss">follows</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">increment</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="1137211517-16">(</span><span class="p" data-group-id="1137211517-16">)</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1336584352-15">{</span><span class="w">
│ │ │ +    </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">Here</span><span class="w"> </span><span class="ss">follows</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">increment</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="1336584352-16">(</span><span class="p" data-group-id="1336584352-16">)</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1137211517-15">}</span></code></pre><h5>Some notes about combined instructions</h5><p>The operands that are different must be at
│ │ │ +</span><span class="p" data-group-id="1336584352-15">}</span></code></pre><h5>Some notes about combined instructions</h5><p>The operands that are different must be at
│ │ │  the beginning of the instruction.  All operands in the last
│ │ │  fragment must have the same operands in all variants of
│ │ │  the specific instruction.</p><p>As an example, the following specific instructions cannot be
│ │ │  implemented as a combined instruction:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_times</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">d</span><span class="w">
│ │ │  </span><span class="ss">i_times</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="ss">d</span><span class="w">
│ │ │  </span><span class="ss">i_times</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">d</span></code></pre><p>We would have to change the order of the operands so that the
│ │ │  two operands that are different are placed first:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_times</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span><span class="w">
│ │ │  </span><span class="ss">i_times</span><span class="w"> </span><span class="ss">x</span><span class="w"> </span><span class="ss">y</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span><span class="w">
│ │ │  </span><span class="ss">i_times</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="w"> </span><span class="ss">d</span></code></pre><p>We can then define:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_times</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">times</span><span class="p">.</span><span class="ss">fetch</span><span class="p">.</span><span class="ss">execute</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">times</span><span class="p">.</span><span class="ss">head</span><span class="w"> </span><span class="p" data-group-id="7761755052-1">{</span><span class="w">
│ │ │ +</span><span class="ss">times</span><span class="p">.</span><span class="ss">head</span><span class="w"> </span><span class="p" data-group-id="0563109330-1">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">op1</span><span class="p">,</span><span class="w"> </span><span class="ss">op2</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7761755052-1">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0563109330-1">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">times</span><span class="p">.</span><span class="nf">fetch</span><span class="p" data-group-id="7761755052-2">(</span><span class="n">Src1</span><span class="p">,</span><span class="w"> </span><span class="n">Src2</span><span class="p" data-group-id="7761755052-2">)</span><span class="w"> </span><span class="p" data-group-id="7761755052-3">{</span><span class="w">
│ │ │ +</span><span class="ss">times</span><span class="p">.</span><span class="nf">fetch</span><span class="p" data-group-id="0563109330-2">(</span><span class="n">Src1</span><span class="p">,</span><span class="w"> </span><span class="n">Src2</span><span class="p" data-group-id="0563109330-2">)</span><span class="w"> </span><span class="p" data-group-id="0563109330-3">{</span><span class="w">
│ │ │      </span><span class="ss">op1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc1</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">op2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$S</span><span class="ss">rc2</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7761755052-3">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0563109330-3">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">times</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="7761755052-4">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="7761755052-4">)</span><span class="w"> </span><span class="p" data-group-id="7761755052-5">{</span><span class="w">
│ │ │ +</span><span class="ss">times</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="0563109330-4">(</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="0563109330-4">)</span><span class="w"> </span><span class="p" data-group-id="0563109330-5">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">Multiply</span><span class="w"> </span><span class="ss">op1</span><span class="w"> </span><span class="ow">and</span><span class="w"> </span><span class="ss">op2</span><span class="p">.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7761755052-5">}</span></code></pre><p>Several instructions can share a group.  As an example, the following
│ │ │ +</span><span class="p" data-group-id="0563109330-5">}</span></code></pre><p>Several instructions can share a group.  As an example, the following
│ │ │  instructions have different names, but in the end they all create a
│ │ │  binary.  The last two operands are common for all of them:</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_bs_init_fail</span><span class="w">       </span><span class="ss">xy</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="o">?</span><span class="w"> </span><span class="ss">x</span><span class="w">
│ │ │  </span><span class="ss">i_bs_init_fail_heap</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="n">I</span><span class="w"> </span><span class="ss">j</span><span class="o">?</span><span class="w"> </span><span class="ss">t</span><span class="o">?</span><span class="w"> </span><span class="ss">x</span><span class="w">
│ │ │  </span><span class="ss">i_bs_init</span><span class="w">                </span><span class="n">W</span><span class="w"> </span><span class="ss">t</span><span class="o">?</span><span class="w"> </span><span class="ss">x</span><span class="w">
│ │ │  </span><span class="ss">i_bs_init_heap</span><span class="w">         </span><span class="n">W</span><span class="w"> </span><span class="n">I</span><span class="w"> </span><span class="ss">t</span><span class="o">?</span><span class="w"> </span><span class="ss">x</span></code></pre><p>The instructions are defined like this (formatted with extra
│ │ │  spaces for clarity):</p><pre><code class="makeup erlang" translate="no"><span class="ss">i_bs_init_fail_heap</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="ss">bs_init</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="ss">fail_heap</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="ss">verify</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="ss">execute</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="ss">i_bs_init_fail</span><span class="w">      </span><span class="p">:=</span><span class="w"> </span><span class="ss">bs_init</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="ss">fail</span><span class="w">      </span><span class="p">.</span><span class="w"> </span><span class="ss">verify</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="ss">execute</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="ss">i_bs_init</span><span class="w">           </span><span class="p">:=</span><span class="w"> </span><span class="ss">bs_init</span><span class="w"> </span><span class="p">.</span><span class="w">           </span><span class="p">.</span><span class="w">  </span><span class="ss">plain</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="ss">execute</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="ss">i_bs_init_heap</span><span class="w">      </span><span class="p">:=</span><span class="w"> </span><span class="ss">bs_init</span><span class="w"> </span><span class="p">.</span><span class="w">               </span><span class="ss">heap</span><span class="w"> </span><span class="p">.</span><span class="w"> </span><span class="ss">execute</span><span class="p">;</span></code></pre><p>Note that the first two instruction have three fragments, while the
│ │ │ -other two only have two fragments.  Here are the fragments:</p><pre><code class="makeup erlang" translate="no"><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">head</span><span class="p" data-group-id="0838302937-1">(</span><span class="p" data-group-id="0838302937-1">)</span><span class="w"> </span><span class="p" data-group-id="0838302937-2">{</span><span class="w">
│ │ │ +other two only have two fragments.  Here are the fragments:</p><pre><code class="makeup erlang" translate="no"><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">head</span><span class="p" data-group-id="4576577115-1">(</span><span class="p" data-group-id="4576577115-1">)</span><span class="w"> </span><span class="p" data-group-id="4576577115-2">{</span><span class="w">
│ │ │      </span><span class="n">Eterm</span><span class="w"> </span><span class="ss">num_bits_term</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Uint</span><span class="w"> </span><span class="ss">num_bits</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">Uint</span><span class="w"> </span><span class="ss">alloc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0838302937-2">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4576577115-2">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">plain</span><span class="p" data-group-id="0838302937-3">(</span><span class="n">NumBits</span><span class="p" data-group-id="0838302937-3">)</span><span class="w"> </span><span class="p" data-group-id="0838302937-4">{</span><span class="w">
│ │ │ +</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">plain</span><span class="p" data-group-id="4576577115-3">(</span><span class="n">NumBits</span><span class="p" data-group-id="4576577115-3">)</span><span class="w"> </span><span class="p" data-group-id="4576577115-4">{</span><span class="w">
│ │ │      </span><span class="ss">num_bits</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$N</span><span class="ss">umBits</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">alloc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0838302937-4">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4576577115-4">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">heap</span><span class="p" data-group-id="0838302937-5">(</span><span class="n">NumBits</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="0838302937-5">)</span><span class="w"> </span><span class="p" data-group-id="0838302937-6">{</span><span class="w">
│ │ │ +</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">heap</span><span class="p" data-group-id="4576577115-5">(</span><span class="n">NumBits</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="4576577115-5">)</span><span class="w"> </span><span class="p" data-group-id="4576577115-6">{</span><span class="w">
│ │ │      </span><span class="ss">num_bits</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$N</span><span class="ss">umBits</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">alloc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$A</span><span class="ss">lloc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0838302937-6">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4576577115-6">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">fail</span><span class="p" data-group-id="0838302937-7">(</span><span class="n">NumBitsTerm</span><span class="p" data-group-id="0838302937-7">)</span><span class="w"> </span><span class="p" data-group-id="0838302937-8">{</span><span class="w">
│ │ │ +</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">fail</span><span class="p" data-group-id="4576577115-7">(</span><span class="n">NumBitsTerm</span><span class="p" data-group-id="4576577115-7">)</span><span class="w"> </span><span class="p" data-group-id="4576577115-8">{</span><span class="w">
│ │ │      </span><span class="ss">num_bits_term</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$N</span><span class="ss">umBitsTerm</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">alloc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0838302937-8">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4576577115-8">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">fail_heap</span><span class="p" data-group-id="0838302937-9">(</span><span class="n">NumBitsTerm</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="0838302937-9">)</span><span class="w"> </span><span class="p" data-group-id="0838302937-10">{</span><span class="w">
│ │ │ +</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">fail_heap</span><span class="p" data-group-id="4576577115-9">(</span><span class="n">NumBitsTerm</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="p" data-group-id="4576577115-9">)</span><span class="w"> </span><span class="p" data-group-id="4576577115-10">{</span><span class="w">
│ │ │      </span><span class="ss">num_bits_term</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$N</span><span class="ss">umBitsTerm</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">alloc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">$A</span><span class="ss">lloc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0838302937-10">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4576577115-10">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">verify</span><span class="p" data-group-id="0838302937-11">(</span><span class="n">Fail</span><span class="p" data-group-id="0838302937-11">)</span><span class="w"> </span><span class="p" data-group-id="0838302937-12">{</span><span class="w">
│ │ │ +</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">verify</span><span class="p" data-group-id="4576577115-11">(</span><span class="n">Fail</span><span class="p" data-group-id="4576577115-11">)</span><span class="w"> </span><span class="p" data-group-id="4576577115-12">{</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">Verify</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">num_bits_term</span><span class="p">,</span><span class="w"> </span><span class="ss">fail</span><span class="w"> </span><span class="ss">using</span><span class="w"> </span><span class="sc">$F</span><span class="n">AIL</span><span class="w">
│ │ │      </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="ss">there</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="ss">problem</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0838302937-12">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4576577115-12">}</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="0838302937-13">(</span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="0838302937-13">)</span><span class="w"> </span><span class="p" data-group-id="0838302937-14">{</span><span class="w">
│ │ │ +</span><span class="ss">bs_init_bits</span><span class="p">.</span><span class="nf">execute</span><span class="p" data-group-id="4576577115-13">(</span><span class="n">Live</span><span class="p">,</span><span class="w"> </span><span class="n">Dst</span><span class="p" data-group-id="4576577115-13">)</span><span class="w"> </span><span class="p" data-group-id="4576577115-14">{</span><span class="w">
│ │ │     </span><span class="o">/</span><span class="o">/</span><span class="w"> </span><span class="n">Long</span><span class="w"> </span><span class="ss">complicated</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="ss">create</span><span class="w"> </span><span class="ss">a</span><span class="w"> </span><span class="ss">binary</span><span class="p">.</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="w">
│ │ │     </span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0838302937-14">}</span></code></pre><p>The full definitions of those instructions can be found in <code class="inline">bs_instrs.tab</code>.
│ │ │ +</span><span class="p" data-group-id="4576577115-14">}</span></code></pre><p>The full definitions of those instructions can be found in <code class="inline">bs_instrs.tab</code>.
│ │ │  The generated code can be found in <code class="inline">beam_warm.h</code>.</p><h3 id="code-generation-for-beamasm" class="section-heading">
│ │ │    <a href="#code-generation-for-beamasm" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Code generation for BeamAsm</span>
│ │ │  </h3>
│ │ │  <p>For the BeamAsm runtime system, the implementation of each instruction is defined
│ │ │  by emitter functions written in C++ that emit the assembly code for each instruction.
│ │ │  There is one emitter function for each family of specific instructions.</p><p>Take for example the <code class="inline">move</code> instruction. In <code class="inline">beam/asm/ops.tab</code> there is a
│ │ │ -single specific instruction for <code class="inline">move</code> defined like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">move</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">d</span></code></pre><p>The implementation is found in <code class="inline">beam/asm/instr_common.cpp</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_move</span><span class="p" data-group-id="1398807684-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Dst</span><span class="p" data-group-id="1398807684-1">)</span><span class="w"> </span><span class="p" data-group-id="1398807684-2">{</span><span class="w">
│ │ │ -    </span><span class="nf">mov_arg</span><span class="p" data-group-id="1398807684-3">(</span><span class="n">Dst</span><span class="p">,</span><span class="w"> </span><span class="n">Src</span><span class="p" data-group-id="1398807684-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1398807684-2">}</span></code></pre><p>The <code class="inline">mov_arg()</code> helper function will handle all combinations of source and destination
│ │ │ -operands.  For example, the instruction <code class="inline">{move,{x,1},{y,1}}</code> will be translated like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mov</span><span class="w"> </span><span class="ss">rdi</span><span class="p">,</span><span class="w"> </span><span class="ss">qword</span><span class="w"> </span><span class="p" data-group-id="8734241872-1">[</span><span class="ss">rbx</span><span class="o">+</span><span class="mi">8</span><span class="p" data-group-id="8734241872-1">]</span><span class="w">
│ │ │ -</span><span class="ss">mov</span><span class="w"> </span><span class="ss">qword</span><span class="w"> </span><span class="p" data-group-id="8734241872-2">[</span><span class="ss">rsp</span><span class="o">+</span><span class="mi">8</span><span class="p" data-group-id="8734241872-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">rdi</span></code></pre><p>while <code class="inline">{move,{integer,42},{x,0}}</code> will be translated like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mov</span><span class="w"> </span><span class="ss">qword</span><span class="w"> </span><span class="p" data-group-id="9329234530-1">[</span><span class="ss">rbx</span><span class="p" data-group-id="9329234530-1">]</span><span class="p">,</span><span class="w"> </span><span class="mi">687</span></code></pre><p>It is possible to define more than one specific instruction, but there will still be
│ │ │ +single specific instruction for <code class="inline">move</code> defined like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">move</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">d</span></code></pre><p>The implementation is found in <code class="inline">beam/asm/instr_common.cpp</code>:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_move</span><span class="p" data-group-id="9911504480-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Dst</span><span class="p" data-group-id="9911504480-1">)</span><span class="w"> </span><span class="p" data-group-id="9911504480-2">{</span><span class="w">
│ │ │ +    </span><span class="nf">mov_arg</span><span class="p" data-group-id="9911504480-3">(</span><span class="n">Dst</span><span class="p">,</span><span class="w"> </span><span class="n">Src</span><span class="p" data-group-id="9911504480-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9911504480-2">}</span></code></pre><p>The <code class="inline">mov_arg()</code> helper function will handle all combinations of source and destination
│ │ │ +operands.  For example, the instruction <code class="inline">{move,{x,1},{y,1}}</code> will be translated like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mov</span><span class="w"> </span><span class="ss">rdi</span><span class="p">,</span><span class="w"> </span><span class="ss">qword</span><span class="w"> </span><span class="p" data-group-id="1811243159-1">[</span><span class="ss">rbx</span><span class="o">+</span><span class="mi">8</span><span class="p" data-group-id="1811243159-1">]</span><span class="w">
│ │ │ +</span><span class="ss">mov</span><span class="w"> </span><span class="ss">qword</span><span class="w"> </span><span class="p" data-group-id="1811243159-2">[</span><span class="ss">rsp</span><span class="o">+</span><span class="mi">8</span><span class="p" data-group-id="1811243159-2">]</span><span class="p">,</span><span class="w"> </span><span class="ss">rdi</span></code></pre><p>while <code class="inline">{move,{integer,42},{x,0}}</code> will be translated like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">mov</span><span class="w"> </span><span class="ss">qword</span><span class="w"> </span><span class="p" data-group-id="6802866039-1">[</span><span class="ss">rbx</span><span class="p" data-group-id="6802866039-1">]</span><span class="p">,</span><span class="w"> </span><span class="mi">687</span></code></pre><p>It is possible to define more than one specific instruction, but there will still be
│ │ │  only one emitter function. For example:</p><pre><code class="makeup erlang" translate="no"><span class="ss">fload</span><span class="w"> </span><span class="n">S</span><span class="w"> </span><span class="ss">l</span><span class="w">
│ │ │  </span><span class="ss">fload</span><span class="w"> </span><span class="ss">q</span><span class="w"> </span><span class="ss">l</span></code></pre><p>By defining <code class="inline">fload</code> like this, the source operand must be a X register, Y register, or
│ │ │  a literal.  If not, the loading will be aborted.  If the instruction instead had been
│ │ │  defined like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">fload</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">l</span></code></pre><p>attempting to load an invalid instruction such as <code class="inline">{fload,{atom,clearly_bad},{fr,0}}</code>
│ │ │  would cause a crash (either at load time or when the instruction was executed).</p><p>Regardless on how many specific instructions there are in the family,
│ │ │ -only a single <code class="inline">emit_fload()</code> function is allowed:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_fload</span><span class="p" data-group-id="8897934290-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Dst</span><span class="p" data-group-id="8897934290-1">)</span><span class="w"> </span><span class="p" data-group-id="8897934290-2">{</span><span class="w">
│ │ │ +only a single <code class="inline">emit_fload()</code> function is allowed:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_fload</span><span class="p" data-group-id="1393850688-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p">,</span><span class="w"> </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Dst</span><span class="p" data-group-id="1393850688-1">)</span><span class="w"> </span><span class="p" data-group-id="1393850688-2">{</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │      </span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8897934290-2">}</span></code></pre><p><a href="" id="handling-a-variable-number-of-operands"></a></p><h4>Handling a variable number of operands</h4><p>Here follows an example of how an instruction with a variable number
│ │ │ +</span><span class="p" data-group-id="1393850688-2">}</span></code></pre><p><a href="" id="handling-a-variable-number-of-operands"></a></p><h4>Handling a variable number of operands</h4><p>Here follows an example of how an instruction with a variable number
│ │ │  of operands could be handled.  One such instructions is
│ │ │ -<code class="inline">select_val/3</code>. Here is an example how it can look like in BEAM code:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5609551828-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="5609551828-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="5609551828-2">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="5609551828-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5609551828-3">}</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="5609551828-4">{</span><span class="ss">list</span><span class="p">,</span><span class="p" data-group-id="5609551828-5">[</span><span class="p" data-group-id="5609551828-6">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5609551828-6">}</span><span class="p">,</span><span class="p" data-group-id="5609551828-7">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5609551828-7">}</span><span class="p">,</span><span class="p" data-group-id="5609551828-8">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="5609551828-8">}</span><span class="p">,</span><span class="p" data-group-id="5609551828-9">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5609551828-9">}</span><span class="p" data-group-id="5609551828-5">]</span><span class="p" data-group-id="5609551828-4">}</span><span class="p" data-group-id="5609551828-1">}</span><span class="p">.</span></code></pre><p>The loader will convert a <code class="inline">{list,[...]}</code> operand to an <code class="inline">u</code> operand whose
│ │ │ +<code class="inline">select_val/3</code>. Here is an example how it can look like in BEAM code:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="6556491034-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="6556491034-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="6556491034-2">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6556491034-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="6556491034-3">}</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="6556491034-4">{</span><span class="ss">list</span><span class="p">,</span><span class="p" data-group-id="6556491034-5">[</span><span class="p" data-group-id="6556491034-6">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="6556491034-6">}</span><span class="p">,</span><span class="p" data-group-id="6556491034-7">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="6556491034-7">}</span><span class="p">,</span><span class="p" data-group-id="6556491034-8">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="6556491034-8">}</span><span class="p">,</span><span class="p" data-group-id="6556491034-9">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6556491034-9">}</span><span class="p" data-group-id="6556491034-5">]</span><span class="p" data-group-id="6556491034-4">}</span><span class="p" data-group-id="6556491034-1">}</span><span class="p">.</span></code></pre><p>The loader will convert a <code class="inline">{list,[...]}</code> operand to an <code class="inline">u</code> operand whose
│ │ │  value is the number of elements in the list, followed by each element in
│ │ │  the list.  The instruction above would be translated to the following
│ │ │ -instruction:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="5722270346-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="5722270346-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="5722270346-2">}</span><span class="p">,</span><span class="p" data-group-id="5722270346-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="5722270346-3">}</span><span class="p">,</span><span class="p" data-group-id="5722270346-4">{</span><span class="ss">u</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5722270346-4">}</span><span class="p">,</span><span class="p" data-group-id="5722270346-5">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="5722270346-5">}</span><span class="p">,</span><span class="p" data-group-id="5722270346-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="5722270346-6">}</span><span class="p">,</span><span class="p" data-group-id="5722270346-7">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="5722270346-7">}</span><span class="p">,</span><span class="p" data-group-id="5722270346-8">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5722270346-8">}</span><span class="p" data-group-id="5722270346-1">}</span></code></pre><p>A definition of a specific instruction for that instruction would look
│ │ │ +instruction:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="2003653391-1">{</span><span class="ss">select_val</span><span class="p">,</span><span class="p" data-group-id="2003653391-2">{</span><span class="ss">x</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="2003653391-2">}</span><span class="p">,</span><span class="p" data-group-id="2003653391-3">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="2003653391-3">}</span><span class="p">,</span><span class="p" data-group-id="2003653391-4">{</span><span class="ss">u</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2003653391-4">}</span><span class="p">,</span><span class="p" data-group-id="2003653391-5">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">b</span><span class="p" data-group-id="2003653391-5">}</span><span class="p">,</span><span class="p" data-group-id="2003653391-6">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="2003653391-6">}</span><span class="p">,</span><span class="p" data-group-id="2003653391-7">{</span><span class="ss">atom</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="2003653391-7">}</span><span class="p">,</span><span class="p" data-group-id="2003653391-8">{</span><span class="ss">f</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2003653391-8">}</span><span class="p" data-group-id="2003653391-1">}</span></code></pre><p>A definition of a specific instruction for that instruction would look
│ │ │  like this:</p><pre><code class="makeup erlang" translate="no"><span class="ss">select_val</span><span class="w"> </span><span class="ss">s</span><span class="w"> </span><span class="ss">f</span><span class="w"> </span><span class="n">I</span><span class="w"> </span><span class="o">*</span></code></pre><p>The <code class="inline">*</code> as the last operand will make sure that the variable operands
│ │ │  are passed in as a <code class="inline">Span</code> of <code class="inline">ArgVal</code> (will be <code class="inline">std::span</code> in C++20 onwards).
│ │ │ -Here is the emitter function:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_select_val</span><span class="p" data-group-id="0038661927-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p">,</span><span class="w">
│ │ │ +Here is the emitter function:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_select_val</span><span class="p" data-group-id="9691246852-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p">,</span><span class="w">
│ │ │                                            </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Fail</span><span class="p">,</span><span class="w">
│ │ │                                            </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Size</span><span class="p">,</span><span class="w">
│ │ │ -                                          </span><span class="ss">const</span><span class="w"> </span><span class="n">Span</span><span class="o">&lt;</span><span class="n">ArgVal</span><span class="o">&gt;</span><span class="w"> </span><span class="err">&amp;</span><span class="ss">args</span><span class="p" data-group-id="0038661927-1">)</span><span class="w"> </span><span class="p" data-group-id="0038661927-2">{</span><span class="w">
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="0038661927-3">(</span><span class="n">Size</span><span class="p">.</span><span class="nf">getValue</span><span class="p" data-group-id="0038661927-4">(</span><span class="p" data-group-id="0038661927-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="ss">args</span><span class="p">.</span><span class="nf">size</span><span class="p" data-group-id="0038661927-5">(</span><span class="p" data-group-id="0038661927-5">)</span><span class="p" data-group-id="0038661927-3">)</span><span class="p">;</span><span class="w">
│ │ │ +                                          </span><span class="ss">const</span><span class="w"> </span><span class="n">Span</span><span class="o">&lt;</span><span class="n">ArgVal</span><span class="o">&gt;</span><span class="w"> </span><span class="err">&amp;</span><span class="ss">args</span><span class="p" data-group-id="9691246852-1">)</span><span class="w"> </span><span class="p" data-group-id="9691246852-2">{</span><span class="w">
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="9691246852-3">(</span><span class="n">Size</span><span class="p">.</span><span class="nf">getValue</span><span class="p" data-group-id="9691246852-4">(</span><span class="p" data-group-id="9691246852-4">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="ss">args</span><span class="p">.</span><span class="nf">size</span><span class="p" data-group-id="9691246852-5">(</span><span class="p" data-group-id="9691246852-5">)</span><span class="p" data-group-id="9691246852-3">)</span><span class="p">;</span><span class="w">
│ │ │         </span><span class="p">.</span><span class="w">
│ │ │         </span><span class="p">.</span><span class="w">
│ │ │         </span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0038661927-2">}</span></code></pre>
│ │ │ +</span><span class="p" data-group-id="9691246852-2">}</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="tracing.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/beamasm.html
│ │ │ @@ -145,26 +145,26 @@
│ │ │  </h2>
│ │ │  <p>The code is loaded very similarly to how it is loaded for the interpreter. Each beam
│ │ │  file is parsed and then optimized through the transformations described in
│ │ │  <a href="beam_makeops.html#defining-transformation-rules">beam_makeops</a>. The transformations
│ │ │  used in BeamAsm are much simpler than the interpreter's, as most of the
│ │ │  transformations for the interpreter are done only to eliminate the instruction
│ │ │  dispatch overhead.</p><p>Then each instruction is encoded using the C++ functions in the
│ │ │ -<code class="inline">jit/$ARCH/instr_*.cpp</code> files. For example:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_is_nonempty_list</span><span class="p" data-group-id="2806812710-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p" data-group-id="2806812710-1">)</span><span class="w"> </span><span class="p" data-group-id="2806812710-2">{</span><span class="w">
│ │ │ -  </span><span class="ss">a</span><span class="p">.</span><span class="nf">test</span><span class="p" data-group-id="2806812710-3">(</span><span class="nf">getArgRef</span><span class="p" data-group-id="2806812710-4">(</span><span class="n">Src</span><span class="p" data-group-id="2806812710-4">)</span><span class="p">,</span><span class="w"> </span><span class="nf">imm</span><span class="p" data-group-id="2806812710-5">(</span><span class="p">_</span><span class="n">TAG_PRIMARY_MASK</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">TAG_PRIMARY_LIST</span><span class="p" data-group-id="2806812710-5">)</span><span class="p" data-group-id="2806812710-3">)</span><span class="p">;</span><span class="w">
│ │ │ -  </span><span class="ss">a</span><span class="p">.</span><span class="nf">jne</span><span class="p" data-group-id="2806812710-6">(</span><span class="ss">labels</span><span class="p" data-group-id="2806812710-7">[</span><span class="n">Fail</span><span class="p">.</span><span class="nf">getLabel</span><span class="p" data-group-id="2806812710-8">(</span><span class="p" data-group-id="2806812710-8">)</span><span class="p" data-group-id="2806812710-7">]</span><span class="p" data-group-id="2806812710-6">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2806812710-2">}</span></code></pre><p><a href="https://github.com/asmjit/asmjit">asmjit</a> provides a fairly straightforward
│ │ │ +<code class="inline">jit/$ARCH/instr_*.cpp</code> files. For example:</p><pre><code class="makeup erlang" translate="no"><span class="ss">void</span><span class="w"> </span><span class="n">BeamModuleAssembler</span><span class="p">:</span><span class="p">:</span><span class="nf">emit_is_nonempty_list</span><span class="p" data-group-id="2709787933-1">(</span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Fail</span><span class="p">,</span><span class="w"> </span><span class="ss">const</span><span class="w"> </span><span class="n">ArgVal</span><span class="w"> </span><span class="err">&amp;</span><span class="n">Src</span><span class="p" data-group-id="2709787933-1">)</span><span class="w"> </span><span class="p" data-group-id="2709787933-2">{</span><span class="w">
│ │ │ +  </span><span class="ss">a</span><span class="p">.</span><span class="nf">test</span><span class="p" data-group-id="2709787933-3">(</span><span class="nf">getArgRef</span><span class="p" data-group-id="2709787933-4">(</span><span class="n">Src</span><span class="p" data-group-id="2709787933-4">)</span><span class="p">,</span><span class="w"> </span><span class="nf">imm</span><span class="p" data-group-id="2709787933-5">(</span><span class="p">_</span><span class="n">TAG_PRIMARY_MASK</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">TAG_PRIMARY_LIST</span><span class="p" data-group-id="2709787933-5">)</span><span class="p" data-group-id="2709787933-3">)</span><span class="p">;</span><span class="w">
│ │ │ +  </span><span class="ss">a</span><span class="p">.</span><span class="nf">jne</span><span class="p" data-group-id="2709787933-6">(</span><span class="ss">labels</span><span class="p" data-group-id="2709787933-7">[</span><span class="n">Fail</span><span class="p">.</span><span class="nf">getLabel</span><span class="p" data-group-id="2709787933-8">(</span><span class="p" data-group-id="2709787933-8">)</span><span class="p" data-group-id="2709787933-7">]</span><span class="p" data-group-id="2709787933-6">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2709787933-2">}</span></code></pre><p><a href="https://github.com/asmjit/asmjit">asmjit</a> provides a fairly straightforward
│ │ │  mapping from a C++ function call to the x86 assembly instruction. The above
│ │ │  instruction tests if the value in the <code class="inline">Src</code> register is a non-empty list and if
│ │ │  it is not then it jumps to the fail label.</p><p>For comparison, the interpreter has 8 combinations and specializations of
│ │ │  this implementation to minimize the instruction dispatch overhead for
│ │ │  common patterns.</p><p>The original register allocation done by the Erlang compiler is used to manage the
│ │ │  liveness of values and the physical registers are statically allocated to keep
│ │ │  the necessary process state. At the moment this is the static register
│ │ │ -allocation on x86-64:</p><pre><code class="makeup erlang" translate="no"><span class="nc">rbx</span><span class="p">:</span><span class="w"> </span><span class="n">ErtsSchedulerRegisters</span><span class="w"> </span><span class="nf">struct</span><span class="w"> </span><span class="p" data-group-id="8847891936-1">(</span><span class="ss">contains</span><span class="w"> </span><span class="ss">x</span><span class="o">/</span><span class="nb">float</span><span class="w"> </span><span class="ss">registers</span><span class="w"> </span><span class="ow">and</span><span class="w"> </span><span class="ss">some</span><span class="w"> </span><span class="ss">metadata</span><span class="p" data-group-id="8847891936-1">)</span><span class="w">
│ │ │ +allocation on x86-64:</p><pre><code class="makeup erlang" translate="no"><span class="nc">rbx</span><span class="p">:</span><span class="w"> </span><span class="n">ErtsSchedulerRegisters</span><span class="w"> </span><span class="nf">struct</span><span class="w"> </span><span class="p" data-group-id="5908667368-1">(</span><span class="ss">contains</span><span class="w"> </span><span class="ss">x</span><span class="o">/</span><span class="nb">float</span><span class="w"> </span><span class="ss">registers</span><span class="w"> </span><span class="ow">and</span><span class="w"> </span><span class="ss">some</span><span class="w"> </span><span class="ss">metadata</span><span class="p" data-group-id="5908667368-1">)</span><span class="w">
│ │ │  </span><span class="nc">rbp</span><span class="p">:</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="ss">frame</span><span class="w"> </span><span class="ss">pointer</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="err">`</span><span class="ss">perf</span><span class="err">`</span><span class="w"> </span><span class="ss">support</span><span class="w"> </span><span class="ss">is</span><span class="w"> </span><span class="ss">enabled</span><span class="p">,</span><span class="w"> </span><span class="ss">otherwise</span><span class="w"> </span><span class="ss">this</span><span class="w">
│ │ │       </span><span class="ss">is</span><span class="w"> </span><span class="ss">an</span><span class="w"> </span><span class="ss">optional</span><span class="w"> </span><span class="ss">save</span><span class="w"> </span><span class="ss">slot</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="ss">stack</span><span class="w"> </span><span class="ss">pointer</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="ss">executing</span><span class="w"> </span><span class="n">C</span><span class="w">
│ │ │       </span><span class="ss">code</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="nc">r12</span><span class="p">:</span><span class="w"> </span><span class="n">Active</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">index</span><span class="w">
│ │ │  </span><span class="nc">r13</span><span class="p">:</span><span class="w"> </span><span class="n">Current</span><span class="w"> </span><span class="ss">running</span><span class="w"> </span><span class="ss">process</span><span class="w">
│ │ │  </span><span class="nc">r14</span><span class="p">:</span><span class="w"> </span><span class="n">Remaining</span><span class="w"> </span><span class="ss">reductions</span><span class="w">
│ │ │  </span><span class="nc">r15</span><span class="p">:</span><span class="w"> </span><span class="n">Erlang</span><span class="w"> </span><span class="ss">heap</span><span class="w"> </span><span class="ss">pointer</span></code></pre><p>Note that all of these are callee save registers under the System V and Windows
│ │ │ @@ -183,21 +183,21 @@
│ │ │  shared and only the arguments to the instructions vary. Using as little memory as
│ │ │  possible has many advantages; less memory is used, loading time decreases,
│ │ │  higher cache hit-rate.</p><p>In BeamAsm we need to achieve something similar since the load-time of a module
│ │ │  scales almost linearly with the amount of memory it uses. Early BeamAsm prototypes
│ │ │  used about double the amount of memory for code as the interpreter, while current
│ │ │  versions use about 10% more. How was this achieved?</p><p>In BeamAsm we heavily use shared code fragments to try to emit as much code as
│ │ │  possible as global shared fragments instead of duplicating the code unnecessarily.
│ │ │ -For instance, the return instruction looks something like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Label</span><span class="w"> </span><span class="ss">yield</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">a</span><span class="p">.</span><span class="nf">newLabel</span><span class="p" data-group-id="2558231317-1">(</span><span class="p" data-group-id="2558231317-1">)</span><span class="p">;</span><span class="w">
│ │ │ +For instance, the return instruction looks something like this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Label</span><span class="w"> </span><span class="ss">yield</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">a</span><span class="p">.</span><span class="nf">newLabel</span><span class="p" data-group-id="5703564190-1">(</span><span class="p" data-group-id="5703564190-1">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">*</span><span class="w"> </span><span class="n">Decrement</span><span class="w"> </span><span class="ss">reduction</span><span class="w"> </span><span class="ss">counter</span><span class="w"> </span><span class="o">*</span><span class="o">/</span><span class="w">
│ │ │ -</span><span class="ss">a</span><span class="p">.</span><span class="nf">dec</span><span class="p" data-group-id="2558231317-2">(</span><span class="n">FCALLS</span><span class="p" data-group-id="2558231317-2">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="ss">a</span><span class="p">.</span><span class="nf">dec</span><span class="p" data-group-id="5703564190-2">(</span><span class="n">FCALLS</span><span class="p" data-group-id="5703564190-2">)</span><span class="p">;</span><span class="w">
│ │ │  </span><span class="o">/</span><span class="o">*</span><span class="w"> </span><span class="n">If</span><span class="w"> </span><span class="n">FCALLS</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">jump</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">yield</span><span class="o">-</span><span class="ss">on</span><span class="o">-</span><span class="ss">return</span><span class="w"> </span><span class="ss">fragment</span><span class="w"> </span><span class="o">*</span><span class="o">/</span><span class="w">
│ │ │ -</span><span class="ss">a</span><span class="p">.</span><span class="nf">jl</span><span class="p" data-group-id="2558231317-3">(</span><span class="nf">resolve_fragment</span><span class="p" data-group-id="2558231317-4">(</span><span class="ss">ga</span><span class="p">-&gt;</span><span class="nf">get_dispatch_return</span><span class="p" data-group-id="2558231317-5">(</span><span class="p" data-group-id="2558231317-5">)</span><span class="p" data-group-id="2558231317-4">)</span><span class="p" data-group-id="2558231317-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="ss">a</span><span class="p">.</span><span class="nf">ret</span><span class="p" data-group-id="2558231317-6">(</span><span class="p" data-group-id="2558231317-6">)</span><span class="p">;</span></code></pre><p>The code above is not exactly what is emitted, but close enough. The thing to note
│ │ │ +</span><span class="ss">a</span><span class="p">.</span><span class="nf">jl</span><span class="p" data-group-id="5703564190-3">(</span><span class="nf">resolve_fragment</span><span class="p" data-group-id="5703564190-4">(</span><span class="ss">ga</span><span class="p">-&gt;</span><span class="nf">get_dispatch_return</span><span class="p" data-group-id="5703564190-5">(</span><span class="p" data-group-id="5703564190-5">)</span><span class="p" data-group-id="5703564190-4">)</span><span class="p" data-group-id="5703564190-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="ss">a</span><span class="p">.</span><span class="nf">ret</span><span class="p" data-group-id="5703564190-6">(</span><span class="p" data-group-id="5703564190-6">)</span><span class="p">;</span></code></pre><p>The code above is not exactly what is emitted, but close enough. The thing to note
│ │ │  is that the code for doing the context switch is never emitted. Instead, we jump
│ │ │  to a global fragment that all return instructions share. This greatly reduces
│ │ │  the amount of code that has to be emitted for each module.</p><h2 id="running-erlang-code" class="section-heading">
│ │ │    <a href="#running-erlang-code" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Running Erlang code</span>
│ │ │ @@ -239,43 +239,43 @@
│ │ │    <a href="#running-c-code" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Running C code</span>
│ │ │  </h2>
│ │ │  <p>As Erlang stacks can be very small, we have to switch over to a different stack
│ │ │  when we need to execute C code (which may expect a much larger stack). This is
│ │ │ -done through <code class="inline">emit_enter_runtime</code> and <code class="inline">emit_leave_runtime</code>, for example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">mov_arg</span><span class="p" data-group-id="4211448406-1">(</span><span class="n">ARG4</span><span class="p">,</span><span class="w"> </span><span class="n">NumFree</span><span class="p" data-group-id="4211448406-1">)</span><span class="p">;</span><span class="w">
│ │ │ +done through <code class="inline">emit_enter_runtime</code> and <code class="inline">emit_leave_runtime</code>, for example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">mov_arg</span><span class="p" data-group-id="7239447392-1">(</span><span class="n">ARG4</span><span class="p">,</span><span class="w"> </span><span class="n">NumFree</span><span class="p" data-group-id="7239447392-1">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">*</span><span class="w"> </span><span class="n">Move</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="ss">stack</span><span class="w"> </span><span class="ow">and</span><span class="w"> </span><span class="ss">swap</span><span class="w"> </span><span class="ss">out</span><span class="w"> </span><span class="ss">our</span><span class="w"> </span><span class="ss">current</span><span class="w"> </span><span class="ss">reductions</span><span class="p">,</span><span class="w"> </span><span class="ss">stack</span><span class="o">-</span><span class="p">,</span><span class="w"> </span><span class="ow">and</span><span class="w">
│ │ │   </span><span class="o">*</span><span class="w"> </span><span class="ss">heap</span><span class="w"> </span><span class="ss">pointer</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">process</span><span class="w"> </span><span class="ss">structure</span><span class="p">.</span><span class="w"> </span><span class="o">*</span><span class="o">/</span><span class="w">
│ │ │ -</span><span class="ss">emit_enter_runtime</span><span class="o">&lt;</span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eReductions</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eStack</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eHeap</span><span class="o">&gt;</span><span class="p" data-group-id="4211448406-2">(</span><span class="p" data-group-id="4211448406-2">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="ss">emit_enter_runtime</span><span class="o">&lt;</span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eReductions</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eStack</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eHeap</span><span class="o">&gt;</span><span class="p" data-group-id="7239447392-2">(</span><span class="p" data-group-id="7239447392-2">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">a</span><span class="p">.</span><span class="nf">mov</span><span class="p" data-group-id="4211448406-3">(</span><span class="n">ARG1</span><span class="p">,</span><span class="w"> </span><span class="ss">c_p</span><span class="p" data-group-id="4211448406-3">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">load_x_reg_array</span><span class="p" data-group-id="4211448406-4">(</span><span class="n">ARG2</span><span class="p" data-group-id="4211448406-4">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">make_move_patch</span><span class="p" data-group-id="4211448406-5">(</span><span class="n">ARG3</span><span class="p">,</span><span class="w"> </span><span class="ss">lambdas</span><span class="p" data-group-id="4211448406-6">[</span><span class="n">Fun</span><span class="p">.</span><span class="nf">getValue</span><span class="p" data-group-id="4211448406-7">(</span><span class="p" data-group-id="4211448406-7">)</span><span class="p" data-group-id="4211448406-6">]</span><span class="p">.</span><span class="ss">patches</span><span class="p" data-group-id="4211448406-5">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="ss">a</span><span class="p">.</span><span class="nf">mov</span><span class="p" data-group-id="7239447392-3">(</span><span class="n">ARG1</span><span class="p">,</span><span class="w"> </span><span class="ss">c_p</span><span class="p" data-group-id="7239447392-3">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">load_x_reg_array</span><span class="p" data-group-id="7239447392-4">(</span><span class="n">ARG2</span><span class="p" data-group-id="7239447392-4">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="nf">make_move_patch</span><span class="p" data-group-id="7239447392-5">(</span><span class="n">ARG3</span><span class="p">,</span><span class="w"> </span><span class="ss">lambdas</span><span class="p" data-group-id="7239447392-6">[</span><span class="n">Fun</span><span class="p">.</span><span class="nf">getValue</span><span class="p" data-group-id="7239447392-7">(</span><span class="p" data-group-id="7239447392-7">)</span><span class="p" data-group-id="7239447392-6">]</span><span class="p">.</span><span class="ss">patches</span><span class="p" data-group-id="7239447392-5">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">*</span><span class="w"> </span><span class="n">Call</span><span class="w"> </span><span class="err">`</span><span class="ss">new_fun</span><span class="err">`</span><span class="p">,</span><span class="w"> </span><span class="ss">asserting</span><span class="w"> </span><span class="ss">that</span><span class="w"> </span><span class="ss">we</span><span class="err">&#39;</span><span class="ss">re</span><span class="w"> </span><span class="ss">on</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="ss">stack</span><span class="p">.</span><span class="w"> </span><span class="o">*</span><span class="o">/</span><span class="w">
│ │ │ -</span><span class="ss">runtime_call</span><span class="o">&lt;</span><span class="mi">4</span><span class="o">&gt;</span><span class="p" data-group-id="4211448406-8">(</span><span class="ss">new_fun</span><span class="p" data-group-id="4211448406-8">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="ss">runtime_call</span><span class="o">&lt;</span><span class="mi">4</span><span class="o">&gt;</span><span class="p" data-group-id="7239447392-8">(</span><span class="ss">new_fun</span><span class="p" data-group-id="7239447392-8">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │  </span><span class="o">/</span><span class="o">*</span><span class="w"> </span><span class="n">Move</span><span class="w"> </span><span class="ss">back</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="n">C</span><span class="w"> </span><span class="ss">stack</span><span class="p">,</span><span class="w"> </span><span class="ow">and</span><span class="w"> </span><span class="ss">read</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">updated</span><span class="w"> </span><span class="ss">values</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">process</span><span class="w">
│ │ │   </span><span class="o">*</span><span class="w"> </span><span class="ss">structure</span><span class="w"> </span><span class="o">*</span><span class="o">/</span><span class="w">
│ │ │ -</span><span class="ss">emit_leave_runtime</span><span class="o">&lt;</span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eReductions</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eStack</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eHeap</span><span class="o">&gt;</span><span class="p" data-group-id="4211448406-9">(</span><span class="p" data-group-id="4211448406-9">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="ss">emit_leave_runtime</span><span class="o">&lt;</span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eReductions</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eStack</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Update</span><span class="p">:</span><span class="p">:</span><span class="ss">eHeap</span><span class="o">&gt;</span><span class="p" data-group-id="7239447392-9">(</span><span class="p" data-group-id="7239447392-9">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -</span><span class="ss">a</span><span class="p">.</span><span class="nf">mov</span><span class="p" data-group-id="4211448406-10">(</span><span class="nf">getXRef</span><span class="p" data-group-id="4211448406-11">(</span><span class="mi">0</span><span class="p" data-group-id="4211448406-11">)</span><span class="p">,</span><span class="w"> </span><span class="n">RET</span><span class="p" data-group-id="4211448406-10">)</span><span class="p">;</span></code></pre><p>All combinations of the <code class="inline">Update</code> constants are legal, but the ones given to
│ │ │ +</span><span class="ss">a</span><span class="p">.</span><span class="nf">mov</span><span class="p" data-group-id="7239447392-10">(</span><span class="nf">getXRef</span><span class="p" data-group-id="7239447392-11">(</span><span class="mi">0</span><span class="p" data-group-id="7239447392-11">)</span><span class="p">,</span><span class="w"> </span><span class="n">RET</span><span class="p" data-group-id="7239447392-10">)</span><span class="p">;</span></code></pre><p>All combinations of the <code class="inline">Update</code> constants are legal, but the ones given to
│ │ │  <code class="inline">emit_leave_runtime</code> <em>must</em> be the same as those given to <code class="inline">emit_enter_runtime</code>.</p><h2 id="tracing-and-nif-loading" class="section-heading">
│ │ │    <a href="#tracing-and-nif-loading" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Tracing and NIF Loading</span>
│ │ │  </h2>
│ │ │  <p>To make tracing and NIF loading work there needs to be a way to intercept
│ │ │  any function call. In the interpreter, this is done by rewriting the loaded
│ │ │  BEAM code, but this is more complicated in BeamAsm as we want to have a fast
│ │ │  and compact way to do this. This is solved by emitting the code below at the
│ │ │ -start of each function (x86 variant below):</p><pre><code class="makeup erlang" translate="no"><span class="w">  </span><span class="mi">0</span><span class="nc">x0</span><span class="p">:</span><span class="w"> </span><span class="ss">short</span><span class="w"> </span><span class="ss">jmp</span><span class="w"> </span><span class="mi">6</span><span class="w"> </span><span class="p" data-group-id="5481697726-1">(</span><span class="ss">address</span><span class="w"> </span><span class="mi">0</span><span class="ss">x8</span><span class="p" data-group-id="5481697726-1">)</span><span class="w">
│ │ │ +start of each function (x86 variant below):</p><pre><code class="makeup erlang" translate="no"><span class="w">  </span><span class="mi">0</span><span class="nc">x0</span><span class="p">:</span><span class="w"> </span><span class="ss">short</span><span class="w"> </span><span class="ss">jmp</span><span class="w"> </span><span class="mi">6</span><span class="w"> </span><span class="p" data-group-id="6207080879-1">(</span><span class="ss">address</span><span class="w"> </span><span class="mi">0</span><span class="ss">x8</span><span class="p" data-group-id="6207080879-1">)</span><span class="w">
│ │ │    </span><span class="mi">0</span><span class="nc">x2</span><span class="p">:</span><span class="w"> </span><span class="ss">nop</span><span class="w">
│ │ │    </span><span class="mi">0</span><span class="nc">x3</span><span class="p">:</span><span class="w"> </span><span class="ss">relative</span><span class="w"> </span><span class="ss">near</span><span class="w"> </span><span class="ss">call</span><span class="w"> </span><span class="ss">to</span><span class="w"> </span><span class="ss">shared</span><span class="w"> </span><span class="ss">breakpoint</span><span class="w"> </span><span class="ss">fragment</span><span class="w">
│ │ │    </span><span class="mi">0</span><span class="nc">x8</span><span class="p">:</span><span class="w"> </span><span class="ss">actual</span><span class="w"> </span><span class="ss">code</span><span class="w"> </span><span class="ss">for</span><span class="w"> </span><span class="ss">function</span></code></pre><p>When code starts to execute it will simply see the <code class="inline">short jmp 6</code> instruction
│ │ │  which skips the prologue and starts to execute the code directly.</p><p>When we want to enable a certain breakpoint we set the jmp target to be 1,
│ │ │  which means it will land on the call to the shared breakpoint fragment. This
│ │ │  fragment checks the current <code class="inline">breakpoint_flag</code> stored in the ErtsCodeInfo of
│ │ │  this function, and then calls <code class="inline">erts_call_nif_early</code> and
│ │ │ @@ -289,31 +289,31 @@
│ │ │    <span class="text">Updating code</span>
│ │ │  </h3>
│ │ │  <p>Because many environments enforce <a href="https://en.wikipedia.org/wiki/W%5EX" title="">W^X</a> it's not always possible to write
│ │ │  directly to the code pages. Because of this we map code twice: once with an
│ │ │  executable page and once with a writable page. Since they're backed by the
│ │ │  same memory, writes to the writable page appear magically in the executable
│ │ │  one.</p><p>The <code class="inline">erts_writable_code_ptr</code> function can be used to get writable pointers
│ │ │ -given a module instance, provided that it has been unsealed first:</p><pre><code class="makeup erlang" translate="no"><span class="nf">for</span><span class="w"> </span><span class="p" data-group-id="0425263073-1">(</span><span class="ss">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="ss">i</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="ss">n</span><span class="p">;</span><span class="w"> </span><span class="ss">i</span><span class="o">++</span><span class="p" data-group-id="0425263073-1">)</span><span class="w"> </span><span class="p" data-group-id="0425263073-2">{</span><span class="w">
│ │ │ +given a module instance, provided that it has been unsealed first:</p><pre><code class="makeup erlang" translate="no"><span class="nf">for</span><span class="w"> </span><span class="p" data-group-id="7189090920-1">(</span><span class="ss">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="ss">i</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="ss">n</span><span class="p">;</span><span class="w"> </span><span class="ss">i</span><span class="o">++</span><span class="p" data-group-id="7189090920-1">)</span><span class="w"> </span><span class="p" data-group-id="7189090920-2">{</span><span class="w">
│ │ │      </span><span class="ss">const</span><span class="w"> </span><span class="n">ErtsCodeInfo</span><span class="o">*</span><span class="w"> </span><span class="ss">ci_exec</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="n">ErtsCodeInfo</span><span class="o">*</span><span class="w"> </span><span class="ss">ci_rw</span><span class="p">;</span><span class="w">
│ │ │      </span><span class="ss">void</span><span class="w"> </span><span class="o">*</span><span class="ss">w_ptr</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nf">erts_unseal_module</span><span class="p" data-group-id="0425263073-3">(</span><span class="err">&amp;</span><span class="ss">modp</span><span class="p">-&gt;</span><span class="ss">curr</span><span class="p" data-group-id="0425263073-3">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">erts_unseal_module</span><span class="p" data-group-id="7189090920-3">(</span><span class="err">&amp;</span><span class="ss">modp</span><span class="p">-&gt;</span><span class="ss">curr</span><span class="p" data-group-id="7189090920-3">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="ss">ci_exec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">code_hdr</span><span class="p">-&gt;</span><span class="ss">functions</span><span class="p" data-group-id="0425263073-4">[</span><span class="ss">i</span><span class="p" data-group-id="0425263073-4">]</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">w_ptr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_writable_code_ptr</span><span class="p" data-group-id="0425263073-5">(</span><span class="err">&amp;</span><span class="ss">modp</span><span class="p">-&gt;</span><span class="ss">curr</span><span class="p">,</span><span class="w"> </span><span class="ss">ci_exec</span><span class="p" data-group-id="0425263073-5">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="ss">ci_rw</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="0425263073-6">(</span><span class="n">ErtsCodeInfo</span><span class="o">*</span><span class="p" data-group-id="0425263073-6">)</span><span class="ss">w_ptr</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">ci_exec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="ss">code_hdr</span><span class="p">-&gt;</span><span class="ss">functions</span><span class="p" data-group-id="7189090920-4">[</span><span class="ss">i</span><span class="p" data-group-id="7189090920-4">]</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">w_ptr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erts_writable_code_ptr</span><span class="p" data-group-id="7189090920-5">(</span><span class="err">&amp;</span><span class="ss">modp</span><span class="p">-&gt;</span><span class="ss">curr</span><span class="p">,</span><span class="w"> </span><span class="ss">ci_exec</span><span class="p" data-group-id="7189090920-5">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="ss">ci_rw</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7189090920-6">(</span><span class="n">ErtsCodeInfo</span><span class="o">*</span><span class="p" data-group-id="7189090920-6">)</span><span class="ss">w_ptr</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nf">uninstall_breakpoint</span><span class="p" data-group-id="0425263073-7">(</span><span class="ss">ci_rw</span><span class="p">,</span><span class="w"> </span><span class="ss">ci_exec</span><span class="p" data-group-id="0425263073-7">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="nf">consolidate_bp_data</span><span class="p" data-group-id="0425263073-8">(</span><span class="ss">modp</span><span class="p">,</span><span class="w"> </span><span class="ss">ci_rw</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="0425263073-8">)</span><span class="p">;</span><span class="w">
│ │ │ -    </span><span class="n">ASSERT</span><span class="p" data-group-id="0425263073-9">(</span><span class="ss">ci_rw</span><span class="p">-&gt;</span><span class="ss">gen_bp</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">NULL</span><span class="p" data-group-id="0425263073-9">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">uninstall_breakpoint</span><span class="p" data-group-id="7189090920-7">(</span><span class="ss">ci_rw</span><span class="p">,</span><span class="w"> </span><span class="ss">ci_exec</span><span class="p" data-group-id="7189090920-7">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="nf">consolidate_bp_data</span><span class="p" data-group-id="7189090920-8">(</span><span class="ss">modp</span><span class="p">,</span><span class="w"> </span><span class="ss">ci_rw</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7189090920-8">)</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">ASSERT</span><span class="p" data-group-id="7189090920-9">(</span><span class="ss">ci_rw</span><span class="p">-&gt;</span><span class="ss">gen_bp</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">NULL</span><span class="p" data-group-id="7189090920-9">)</span><span class="p">;</span><span class="w">
│ │ │  
│ │ │ -    </span><span class="nf">erts_seal_module</span><span class="p" data-group-id="0425263073-10">(</span><span class="err">&amp;</span><span class="ss">modp</span><span class="p">-&gt;</span><span class="ss">curr</span><span class="p" data-group-id="0425263073-10">)</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0425263073-2">}</span></code></pre><p>Without the module instance there's no reliable way to figure out the writable
│ │ │ +    </span><span class="nf">erts_seal_module</span><span class="p" data-group-id="7189090920-10">(</span><span class="err">&amp;</span><span class="ss">modp</span><span class="p">-&gt;</span><span class="ss">curr</span><span class="p" data-group-id="7189090920-10">)</span><span class="p">;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7189090920-2">}</span></code></pre><p>Without the module instance there's no reliable way to figure out the writable
│ │ │  address of a code page, and we rely on <em>address space layout randomization</em>
│ │ │  (ASLR) to make it difficult to guess. On some platforms, security is further
│ │ │  enhanced by protecting the writable area from writes until the module has been
│ │ │  unsealed by <code class="inline">erts_unseal_module</code>.</p><h3 id="export-tracing" class="section-heading">
│ │ │    <a href="#export-tracing" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │ @@ -393,15 +393,15 @@
│ │ │  </span><span class="ss">perf</span><span class="w"> </span><span class="ss">script</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">perf</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="p">#</span><span class="w"> </span><span class="ss">run</span><span class="w"> </span><span class="ss">stackcollapse</span><span class="w">
│ │ │  </span><span class="ss">stackcollapse</span><span class="o">-</span><span class="ss">perf</span><span class="p">.</span><span class="ss">pl</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">perf</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">folded</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="p">#</span><span class="w"> </span><span class="n">Create</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">svg</span><span class="w">
│ │ │  </span><span class="ss">flamegraph</span><span class="p">.</span><span class="ss">pl</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">folded</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">svg</span></code></pre><p>We get a graph that would look something like this:</p><p><img src="assets/perf-beamasm.svg" alt="Linux Perf FlameGraph: dialyzer PLT build"/></p><p>You can view a larger version <a href="assets/perf-beamasm.svg">here</a>. It contains
│ │ │  the same information, but it is easier to share with others as it does
│ │ │  not need the symbols in the executable.</p><p>Using the same data we can also produce a graph where the scheduler profile data
│ │ │ -has been merged by using <code class="inline">sed</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">#</span><span class="p">#</span><span class="w"> </span><span class="n">Strip</span><span class="w"> </span><span class="p" data-group-id="5895815976-1">[</span><span class="mi">0</span><span class="o">-</span><span class="mi">9</span><span class="p" data-group-id="5895815976-1">]</span><span class="o">+</span><span class="p">_</span><span class="w"> </span><span class="ow">and</span><span class="o">/</span><span class="ow">or</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="5895815976-2">[</span><span class="mi">0</span><span class="o">-</span><span class="mi">9</span><span class="p" data-group-id="5895815976-2">]</span><span class="o">+</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">scheduler</span><span class="w"> </span><span class="ss">names</span><span class="w">
│ │ │ +has been merged by using <code class="inline">sed</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">#</span><span class="p">#</span><span class="w"> </span><span class="n">Strip</span><span class="w"> </span><span class="p" data-group-id="7208623147-1">[</span><span class="mi">0</span><span class="o">-</span><span class="mi">9</span><span class="p" data-group-id="7208623147-1">]</span><span class="o">+</span><span class="p">_</span><span class="w"> </span><span class="ow">and</span><span class="o">/</span><span class="ow">or</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="7208623147-2">[</span><span class="mi">0</span><span class="o">-</span><span class="mi">9</span><span class="p" data-group-id="7208623147-2">]</span><span class="o">+</span><span class="w"> </span><span class="ss">from</span><span class="w"> </span><span class="ss">all</span><span class="w"> </span><span class="ss">scheduler</span><span class="w"> </span><span class="ss">names</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="p">#</span><span class="w"> </span><span class="ss">scheduler</span><span class="w"> </span><span class="ss">names</span><span class="w"> </span><span class="ss">changed</span><span class="w"> </span><span class="ss">in</span><span class="w"> </span><span class="n">OTP26</span><span class="p">,</span><span class="w"> </span><span class="ss">hence</span><span class="w"> </span><span class="ss">two</span><span class="w"> </span><span class="ss">expressions</span><span class="w">
│ │ │  </span><span class="ss">sed</span><span class="w"> </span><span class="o">-</span><span class="ss">e</span><span class="w"> </span><span class="ss">&#39;s/^[0-9]\+_//&#39;</span><span class="w"> </span><span class="o">-</span><span class="ss">e</span><span class="w"> </span><span class="ss">&#39;s/^erts_\([^_]\+\)_[0-9]\+/erts_\1/&#39;</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">folded</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">folded_sched</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="p">#</span><span class="w"> </span><span class="n">Create</span><span class="w"> </span><span class="ss">the</span><span class="w"> </span><span class="ss">svg</span><span class="w">
│ │ │  </span><span class="ss">flamegraph</span><span class="p">.</span><span class="ss">pl</span><span class="w"> </span><span class="ss">out</span><span class="p">.</span><span class="ss">folded_sched</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="ss">out_sched</span><span class="p">.</span><span class="ss">svg</span></code></pre><p><img src="assets/perf-beamasm-merged.svg" alt="Linux Perf FlameGraph: dialyzer PLT build"/></p><p>You can view a larger version <a href="assets/perf-beamasm-merged.svg">here</a>.
│ │ │  There are many different transformations that you can do to make the graph show
│ │ │  you what you want.</p><h3 id="annotate-perf-functions" class="section-heading">
│ │ │    <a href="#annotate-perf-functions" class="hover-link">
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/codeloading.html
│ │ │ @@ -163,16 +163,16 @@
│ │ │  only be done by one loader process at a time. A second loader process
│ │ │  trying to enter finishing phase will be suspended until the first
│ │ │  loader is done. This will only block the process, the scheduler is
│ │ │  free to schedule other work while the second loader is waiting. (See
│ │ │  <code class="inline">erts_try_seize_code_load_permission</code> and
│ │ │  <code class="inline">erts_release_code_load_permission</code>).</p><p>The ability to prepare several modules in parallel is not currently
│ │ │  used as almost all code loading is serialized by the code_server
│ │ │ -process. The BIF interface is however prepared for this.</p><pre><code class="makeup erlang" translate="no"><span class="w">  </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">prepare_loading</span><span class="p" data-group-id="3977048715-1">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="3977048715-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">LoaderState</span><span class="w">
│ │ │ -  </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">finish_loading</span><span class="p" data-group-id="3977048715-2">(</span><span class="p" data-group-id="3977048715-3">[</span><span class="n">LoaderState</span><span class="p" data-group-id="3977048715-3">]</span><span class="p" data-group-id="3977048715-2">)</span></code></pre><p>The idea is that <code class="inline">prepare_loading</code> could be called in parallel for
│ │ │ +process. The BIF interface is however prepared for this.</p><pre><code class="makeup erlang" translate="no"><span class="w">  </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">prepare_loading</span><span class="p" data-group-id="5154876448-1">(</span><span class="n">Module</span><span class="p">,</span><span class="w"> </span><span class="n">Code</span><span class="p" data-group-id="5154876448-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">LoaderState</span><span class="w">
│ │ │ +  </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">finish_loading</span><span class="p" data-group-id="5154876448-2">(</span><span class="p" data-group-id="5154876448-3">[</span><span class="n">LoaderState</span><span class="p" data-group-id="5154876448-3">]</span><span class="p" data-group-id="5154876448-2">)</span></code></pre><p>The idea is that <code class="inline">prepare_loading</code> could be called in parallel for
│ │ │  different modules and returns a &quot;magic binary&quot; containing the internal
│ │ │  state of each prepared module. Function <code class="inline">finish_loading</code> could take a
│ │ │  list of such states and do the finishing of all of them in one go.</p><p>Currently we use the legacy BIF <code class="inline">erlang:load_module</code> which is now
│ │ │  implemented in Erlang by calling the above two functions in
│ │ │  sequence. Function <code class="inline">finish_loading</code> is limited to only accepts a list
│ │ │  with one module state as we do not yet use the multi module loading
│ │ │  feature.</p><h2 id="the-finishing-sequence" class="section-heading">
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/crash_dump.html
│ │ │ @@ -401,21 +401,21 @@
│ │ │  <a href="erlang.html#put/2"><code class="inline">put/2</code></a> and <a href="erlang.html#get/1"><code class="inline">get/1</code></a> thing) is non-empty.</p><p>The raw memory information can be decoded by the Crashdump Viewer tool. You can
│ │ │  then see the stack dump, the message queue (if any), and the dictionary (if
│ │ │  any).</p><p>The stack dump is a dump of the Erlang process stack. Most of the live data
│ │ │  (that is, variables currently in use) are placed on the stack; thus this can be
│ │ │  interesting. One has to &quot;guess&quot; what is what, but as the information is
│ │ │  symbolic, thorough reading of this information can be useful. As an example, we
│ │ │  can find the state variable of the Erlang primitive loader online <code class="inline">(5)</code> and
│ │ │ -<code class="inline">(6)</code> in the following example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9632916860-1">(</span><span class="mi">1</span><span class="p" data-group-id="9632916860-1">)</span><span class="w">  </span><span class="mi">3</span><span class="ss">cac44</span><span class="w">   </span><span class="n">Return</span><span class="w"> </span><span class="ss">addr</span><span class="w"> </span><span class="mi">0</span><span class="nf">x13BF58</span><span class="w"> </span><span class="p" data-group-id="9632916860-2">(</span><span class="o">&lt;</span><span class="ss">terminate</span><span class="w"> </span><span class="ss">process</span><span class="w"> </span><span class="ss">normally</span><span class="o">&gt;</span><span class="p" data-group-id="9632916860-2">)</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9632916860-3">(</span><span class="mi">2</span><span class="p" data-group-id="9632916860-3">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9632916860-4">(</span><span class="mi">0</span><span class="p" data-group-id="9632916860-4">)</span><span class="w">     </span><span class="p" data-group-id="9632916860-5">[</span><span class="s">&quot;/view/siri_r10_dev/clearcase/otp/erts/lib/kernel/ebin&quot;</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9632916860-6">(</span><span class="mi">3</span><span class="p" data-group-id="9632916860-6">)</span><span class="w">            </span><span class="s">&quot;/view/siri_r10_dev/clearcase/otp/erts/lib/stdlib/ebin&quot;</span><span class="p" data-group-id="9632916860-5">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9632916860-7">(</span><span class="mi">4</span><span class="p" data-group-id="9632916860-7">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9632916860-8">(</span><span class="mi">1</span><span class="p" data-group-id="9632916860-8">)</span><span class="w">     </span><span class="o">&lt;</span><span class="mf">0.1</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9632916860-9">(</span><span class="mi">5</span><span class="p" data-group-id="9632916860-9">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9632916860-10">(</span><span class="mi">2</span><span class="p" data-group-id="9632916860-10">)</span><span class="w">     </span><span class="p" data-group-id="9632916860-11">{</span><span class="ss">state</span><span class="p">,</span><span class="p" data-group-id="9632916860-12">[</span><span class="p" data-group-id="9632916860-12">]</span><span class="p">,</span><span class="ss">none</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">6.7085890</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">undefined</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">7.9000327</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9632916860-13">(</span><span class="mi">6</span><span class="p" data-group-id="9632916860-13">)</span><span class="w">            </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">8.116480692</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.2</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">infinity</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">9.10708760</span><span class="o">&gt;</span><span class="p" data-group-id="9632916860-11">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9632916860-14">(</span><span class="mi">7</span><span class="p" data-group-id="9632916860-14">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9632916860-15">(</span><span class="mi">3</span><span class="p" data-group-id="9632916860-15">)</span><span class="w">     </span><span class="ss">infinity</span></code></pre><p>When interpreting the data for a process, it is helpful to know that anonymous
│ │ │ +<code class="inline">(6)</code> in the following example:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9699696955-1">(</span><span class="mi">1</span><span class="p" data-group-id="9699696955-1">)</span><span class="w">  </span><span class="mi">3</span><span class="ss">cac44</span><span class="w">   </span><span class="n">Return</span><span class="w"> </span><span class="ss">addr</span><span class="w"> </span><span class="mi">0</span><span class="nf">x13BF58</span><span class="w"> </span><span class="p" data-group-id="9699696955-2">(</span><span class="o">&lt;</span><span class="ss">terminate</span><span class="w"> </span><span class="ss">process</span><span class="w"> </span><span class="ss">normally</span><span class="o">&gt;</span><span class="p" data-group-id="9699696955-2">)</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9699696955-3">(</span><span class="mi">2</span><span class="p" data-group-id="9699696955-3">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9699696955-4">(</span><span class="mi">0</span><span class="p" data-group-id="9699696955-4">)</span><span class="w">     </span><span class="p" data-group-id="9699696955-5">[</span><span class="s">&quot;/view/siri_r10_dev/clearcase/otp/erts/lib/kernel/ebin&quot;</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9699696955-6">(</span><span class="mi">3</span><span class="p" data-group-id="9699696955-6">)</span><span class="w">            </span><span class="s">&quot;/view/siri_r10_dev/clearcase/otp/erts/lib/stdlib/ebin&quot;</span><span class="p" data-group-id="9699696955-5">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9699696955-7">(</span><span class="mi">4</span><span class="p" data-group-id="9699696955-7">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9699696955-8">(</span><span class="mi">1</span><span class="p" data-group-id="9699696955-8">)</span><span class="w">     </span><span class="o">&lt;</span><span class="mf">0.1</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9699696955-9">(</span><span class="mi">5</span><span class="p" data-group-id="9699696955-9">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9699696955-10">(</span><span class="mi">2</span><span class="p" data-group-id="9699696955-10">)</span><span class="w">     </span><span class="p" data-group-id="9699696955-11">{</span><span class="ss">state</span><span class="p">,</span><span class="p" data-group-id="9699696955-12">[</span><span class="p" data-group-id="9699696955-12">]</span><span class="p">,</span><span class="ss">none</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">6.7085890</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">undefined</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">7.9000327</span><span class="o">&gt;</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9699696955-13">(</span><span class="mi">6</span><span class="p" data-group-id="9699696955-13">)</span><span class="w">            </span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">8.116480692</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.2</span><span class="o">&gt;</span><span class="p">,</span><span class="ss">infinity</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_prim_loader</span><span class="p">.</span><span class="mf">9.10708760</span><span class="o">&gt;</span><span class="p" data-group-id="9699696955-11">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9699696955-14">(</span><span class="mi">7</span><span class="p" data-group-id="9699696955-14">)</span><span class="w">  </span><span class="nf">y</span><span class="p" data-group-id="9699696955-15">(</span><span class="mi">3</span><span class="p" data-group-id="9699696955-15">)</span><span class="w">     </span><span class="ss">infinity</span></code></pre><p>When interpreting the data for a process, it is helpful to know that anonymous
│ │ │  function objects (funs) are given the following:</p><ul><li>A name constructed from the name of the function in which they are created</li><li>A number (starting with 0) indicating the number of that fun within that
│ │ │  function</li></ul><h2 id="atoms" class="section-heading">
│ │ │    <a href="#atoms" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Atoms</span>
│ │ │  </h2>
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/driver.html
│ │ │ @@ -364,41 +364,41 @@
│ │ │  <p>Before a driver can be called from Erlang, it must be loaded and opened. Loading
│ │ │  is done using the <a href="../../../lib/kernel-10.2.7.2/doc/html/erl_ddll.html"><code class="inline">erl_ddll</code></a> module (the <a href="../../../lib/kernel-10.2.7.2/doc/html/erl_ddll.html"><code class="inline">erl_ddll</code></a> driver that loads dynamic
│ │ │  driver is actually a driver itself). If loading is successful, the port can be
│ │ │  opened with <a href="erlang.html#open_port/2"><code class="inline">open_port/2</code></a>. The port name must match the name of
│ │ │  the shared library and the name in the driver entry structure.</p><p>When the port has been opened, the driver can be called. In the <code class="inline">pg_sync</code>
│ │ │  example, we do not have any data from the port, only the return value from the
│ │ │  <a href="erlang.html#port_control/3"><code class="inline">port_control/3</code></a>.</p><p>The following code is the Erlang part of the synchronous postgres driver,
│ │ │ -<code class="inline">pg_sync.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="7320468427-1">(</span><span class="ss">pg_sync</span><span class="p" data-group-id="7320468427-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">pg_sync.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5968359547-1">(</span><span class="ss">pg_sync</span><span class="p" data-group-id="5968359547-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7320468427-2">(</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="7320468427-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7320468427-3">(</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="7320468427-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="7320468427-4">(</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="7320468427-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5968359547-2">(</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="5968359547-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5968359547-3">(</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="5968359547-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="5968359547-4">(</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="5968359547-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="7320468427-5">(</span><span class="p" data-group-id="7320468427-6">[</span><span class="ss">connect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">disconnect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">select</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="7320468427-6">]</span><span class="p" data-group-id="7320468427-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5968359547-5">(</span><span class="p" data-group-id="5968359547-6">[</span><span class="ss">connect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">disconnect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">select</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="5968359547-6">]</span><span class="p" data-group-id="5968359547-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">connect</span><span class="p" data-group-id="7320468427-7">(</span><span class="n">ConnectStr</span><span class="p" data-group-id="7320468427-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="7320468427-8">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;pg_sync&quot;</span><span class="p" data-group-id="7320468427-8">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">connect</span><span class="p" data-group-id="5968359547-7">(</span><span class="n">ConnectStr</span><span class="p" data-group-id="5968359547-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="5968359547-8">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;pg_sync&quot;</span><span class="p" data-group-id="5968359547-8">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7320468427-9">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="7320468427-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="n">E</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="7320468427-10">(</span><span class="p" data-group-id="7320468427-11">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="p" data-group-id="7320468427-11">}</span><span class="p" data-group-id="7320468427-10">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="5968359547-9">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="5968359547-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="n">E</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="5968359547-10">(</span><span class="p" data-group-id="5968359547-11">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="p" data-group-id="5968359547-11">}</span><span class="p" data-group-id="5968359547-10">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="7320468427-12">(</span><span class="p" data-group-id="7320468427-13">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p" data-group-id="7320468427-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7320468427-14">[</span><span class="p" data-group-id="7320468427-14">]</span><span class="p" data-group-id="7320468427-12">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="7320468427-15">(</span><span class="nf">port_control</span><span class="p" data-group-id="7320468427-16">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="n">ConnectStr</span><span class="p" data-group-id="7320468427-16">)</span><span class="p" data-group-id="7320468427-15">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ -        </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7320468427-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="7320468427-17">}</span><span class="p">;</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="5968359547-12">(</span><span class="p" data-group-id="5968359547-13">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p" data-group-id="5968359547-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5968359547-14">[</span><span class="p" data-group-id="5968359547-14">]</span><span class="p" data-group-id="5968359547-12">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="5968359547-15">(</span><span class="nf">port_control</span><span class="p" data-group-id="5968359547-16">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="n">ConnectStr</span><span class="p" data-group-id="5968359547-16">)</span><span class="p" data-group-id="5968359547-15">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +        </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="5968359547-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="5968359547-17">}</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="n">Error</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Error</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">disconnect</span><span class="p" data-group-id="7320468427-18">(</span><span class="n">Port</span><span class="p" data-group-id="7320468427-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">R</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="7320468427-19">(</span><span class="nf">port_control</span><span class="p" data-group-id="7320468427-20">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p" data-group-id="7320468427-20">)</span><span class="p" data-group-id="7320468427-19">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">port_close</span><span class="p" data-group-id="7320468427-21">(</span><span class="n">Port</span><span class="p" data-group-id="7320468427-21">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">disconnect</span><span class="p" data-group-id="5968359547-18">(</span><span class="n">Port</span><span class="p" data-group-id="5968359547-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">R</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="5968359547-19">(</span><span class="nf">port_control</span><span class="p" data-group-id="5968359547-20">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p" data-group-id="5968359547-20">)</span><span class="p" data-group-id="5968359547-19">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">port_close</span><span class="p" data-group-id="5968359547-21">(</span><span class="n">Port</span><span class="p" data-group-id="5968359547-21">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="n">R</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">select</span><span class="p" data-group-id="7320468427-22">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="7320468427-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">binary_to_term</span><span class="p" data-group-id="7320468427-23">(</span><span class="nf">port_control</span><span class="p" data-group-id="7320468427-24">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="7320468427-24">)</span><span class="p" data-group-id="7320468427-23">)</span><span class="p">.</span></code></pre><p>The API is simple:</p><ul><li><code class="inline">connect/1</code> loads the driver, opens it, and logs on to the database, returning
│ │ │ +</span><span class="nf">select</span><span class="p" data-group-id="5968359547-22">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="5968359547-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">binary_to_term</span><span class="p" data-group-id="5968359547-23">(</span><span class="nf">port_control</span><span class="p" data-group-id="5968359547-24">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="5968359547-24">)</span><span class="p" data-group-id="5968359547-23">)</span><span class="p">.</span></code></pre><p>The API is simple:</p><ul><li><code class="inline">connect/1</code> loads the driver, opens it, and logs on to the database, returning
│ │ │  the Erlang port if successful.</li><li><code class="inline">select/2</code> sends a query to the driver and returns the result.</li><li><code class="inline">disconnect/1</code> closes the database connection and the driver. (However, it
│ │ │  does not unload it.)</li></ul><p>The connection string is to be a connection string for postgres.</p><p>The driver is loaded with <a href="../../../lib/kernel-10.2.7.2/doc/html/erl_ddll.html#load_driver/2"><code class="inline">erl_ddll:load_driver/2</code></a>. If this is successful, or if
│ │ │  it is already loaded, it is opened. This will call the <code class="inline">start</code> function in the
│ │ │  driver.</p><p>We use the <a href="erlang.html#port_control/3"><code class="inline">port_control/3</code></a> function for all calls into the
│ │ │  driver. The result from the driver is returned immediately and converted to
│ │ │  terms by calling <a href="erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>. (We trust that the
│ │ │  terms returned from the driver are well-formed, otherwise the <a href="erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>
│ │ │ @@ -536,51 +536,51 @@
│ │ │  successful, or error if it is not. If the connection is not yet established, we
│ │ │  simply return; <code class="inline">ready_io</code> is called again.</p><p>If we have a result from a connect, indicated by having data in the <code class="inline">x</code> buffer,
│ │ │  we no longer need to select on output (<a href="../../../erts-15.2.7.3/doc/html/driver_entry.html#ready_output" title=""><code class="inline">ready_output</code></a>), so we remove this by
│ │ │  calling <a href="../../../erts-15.2.7.3/doc/html/erl_driver.html#driver_select" title=""><code class="inline">driver_select</code></a>.</p><p>If we are not connecting, we wait for results from a <code class="inline">PQsendQuery</code>, so we get
│ │ │  the result and return it. The encoding is done with the same functions as in the
│ │ │  earlier example.</p><p>Error handling is to be added here, for example, checking that the socket is
│ │ │  still open, but this is only a simple example.</p><p>The Erlang part of the asynchronous driver consists of the sample file
│ │ │ -<code class="inline">pg_async.erl</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1034491706-1">(</span><span class="ss">pg_async</span><span class="p" data-group-id="1034491706-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">pg_async.erl</code>.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9684221863-1">(</span><span class="ss">pg_async</span><span class="p" data-group-id="9684221863-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1034491706-2">(</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="sc">$C</span><span class="p" data-group-id="1034491706-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1034491706-3">(</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="sc">$D</span><span class="p" data-group-id="1034491706-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="1034491706-4">(</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="sc">$S</span><span class="p" data-group-id="1034491706-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9684221863-2">(</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="sc">$C</span><span class="p" data-group-id="9684221863-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9684221863-3">(</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="sc">$D</span><span class="p" data-group-id="9684221863-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">define</span><span class="p" data-group-id="9684221863-4">(</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="sc">$S</span><span class="p" data-group-id="9684221863-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1034491706-5">(</span><span class="p" data-group-id="1034491706-6">[</span><span class="ss">connect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">disconnect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">select</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="1034491706-6">]</span><span class="p" data-group-id="1034491706-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9684221863-5">(</span><span class="p" data-group-id="9684221863-6">[</span><span class="ss">connect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">disconnect</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">select</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9684221863-6">]</span><span class="p" data-group-id="9684221863-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">connect</span><span class="p" data-group-id="1034491706-7">(</span><span class="n">ConnectStr</span><span class="p" data-group-id="1034491706-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="1034491706-8">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;pg_async&quot;</span><span class="p" data-group-id="1034491706-8">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">connect</span><span class="p" data-group-id="9684221863-7">(</span><span class="n">ConnectStr</span><span class="p" data-group-id="9684221863-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="9684221863-8">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;pg_async&quot;</span><span class="p" data-group-id="9684221863-8">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="1034491706-9">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="1034491706-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="1034491706-10">(</span><span class="p" data-group-id="1034491706-11">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="1034491706-11">}</span><span class="p" data-group-id="1034491706-10">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9684221863-9">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="9684221863-9">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ +        </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="9684221863-10">(</span><span class="p" data-group-id="9684221863-11">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">could_not_load_driver</span><span class="p" data-group-id="9684221863-11">}</span><span class="p" data-group-id="9684221863-10">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="1034491706-12">(</span><span class="p" data-group-id="1034491706-13">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p" data-group-id="1034491706-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1034491706-14">[</span><span class="ss">binary</span><span class="p" data-group-id="1034491706-14">]</span><span class="p" data-group-id="1034491706-12">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">port_control</span><span class="p" data-group-id="1034491706-15">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="n">ConnectStr</span><span class="p" data-group-id="1034491706-15">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">return_port_data</span><span class="p" data-group-id="1034491706-16">(</span><span class="n">Port</span><span class="p" data-group-id="1034491706-16">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +    </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="9684221863-12">(</span><span class="p" data-group-id="9684221863-13">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">MODULE</span><span class="p" data-group-id="9684221863-13">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9684221863-14">[</span><span class="ss">binary</span><span class="p" data-group-id="9684221863-14">]</span><span class="p" data-group-id="9684221863-12">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">port_control</span><span class="p" data-group-id="9684221863-15">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_CONNECT</span><span class="p">,</span><span class="w"> </span><span class="n">ConnectStr</span><span class="p" data-group-id="9684221863-15">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">return_port_data</span><span class="p" data-group-id="9684221863-16">(</span><span class="n">Port</span><span class="p" data-group-id="9684221863-16">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="p" data-group-id="1034491706-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="1034491706-17">}</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="p" data-group-id="9684221863-17">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="9684221863-17">}</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="n">Error</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Error</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">disconnect</span><span class="p" data-group-id="1034491706-18">(</span><span class="n">Port</span><span class="p" data-group-id="1034491706-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">port_control</span><span class="p" data-group-id="1034491706-19">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p" data-group-id="1034491706-19">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">R</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">return_port_data</span><span class="p" data-group-id="1034491706-20">(</span><span class="n">Port</span><span class="p" data-group-id="1034491706-20">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">port_close</span><span class="p" data-group-id="1034491706-21">(</span><span class="n">Port</span><span class="p" data-group-id="1034491706-21">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">disconnect</span><span class="p" data-group-id="9684221863-18">(</span><span class="n">Port</span><span class="p" data-group-id="9684221863-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">port_control</span><span class="p" data-group-id="9684221863-19">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_DISCONNECT</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;&quot;</span><span class="p" data-group-id="9684221863-19">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">R</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">return_port_data</span><span class="p" data-group-id="9684221863-20">(</span><span class="n">Port</span><span class="p" data-group-id="9684221863-20">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">port_close</span><span class="p" data-group-id="9684221863-21">(</span><span class="n">Port</span><span class="p" data-group-id="9684221863-21">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="n">R</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">select</span><span class="p" data-group-id="1034491706-22">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="1034491706-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">port_control</span><span class="p" data-group-id="1034491706-23">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="1034491706-23">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">return_port_data</span><span class="p" data-group-id="1034491706-24">(</span><span class="n">Port</span><span class="p" data-group-id="1034491706-24">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">select</span><span class="p" data-group-id="9684221863-22">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="9684221863-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">port_control</span><span class="p" data-group-id="9684221863-23">(</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="o">?</span><span class="n">DRV_SELECT</span><span class="p">,</span><span class="w"> </span><span class="n">Query</span><span class="p" data-group-id="9684221863-23">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">return_port_data</span><span class="p" data-group-id="9684221863-24">(</span><span class="n">Port</span><span class="p" data-group-id="9684221863-24">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">return_port_data</span><span class="p" data-group-id="1034491706-25">(</span><span class="n">Port</span><span class="p" data-group-id="1034491706-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">return_port_data</span><span class="p" data-group-id="9684221863-25">(</span><span class="n">Port</span><span class="p" data-group-id="9684221863-25">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="1034491706-26">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1034491706-27">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="1034491706-27">}</span><span class="p" data-group-id="1034491706-26">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">binary_to_term</span><span class="p" data-group-id="1034491706-28">(</span><span class="n">Data</span><span class="p" data-group-id="1034491706-28">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="9684221863-26">{</span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9684221863-27">{</span><span class="ss">data</span><span class="p">,</span><span class="w"> </span><span class="n">Data</span><span class="p" data-group-id="9684221863-27">}</span><span class="p" data-group-id="9684221863-26">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">binary_to_term</span><span class="p" data-group-id="9684221863-28">(</span><span class="n">Data</span><span class="p" data-group-id="9684221863-28">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>The Erlang code is slightly different, as we do not return the result
│ │ │  synchronously from <a href="erlang.html#port_control/3"><code class="inline">port_control/3</code></a>, instead we get it from <a href="../../../erts-15.2.7.3/doc/html/erl_driver.html#driver_output" title=""><code class="inline">driver_output</code></a> as
│ │ │  data in the message queue. The function <code class="inline">return_port_data</code> above receives data
│ │ │  from the port. As the data is in binary format, we use
│ │ │  <a href="erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a> to convert it to an Erlang term. Notice
│ │ │  that the driver is opened in binary mode (<a href="erlang.html#open_port/2"><code class="inline">open_port/2</code></a> is
│ │ │  called with option <code class="inline">[binary]</code>). This means that data sent from the driver to the
│ │ │ @@ -677,59 +677,59 @@
│ │ │      *rp++ = ERL_DRV_LIST;
│ │ │      *rp++ = n+1;
│ │ │      driver_output_term(port, result, result_n);
│ │ │      delete[] result;
│ │ │      delete d;
│ │ │  }</code></pre><p>This driver is called like the others from Erlang. However, as we use
│ │ │  <a href="../../../erts-15.2.7.3/doc/html/erl_driver.html#driver_output_term" title=""><code class="inline">driver_output_term</code></a>, there is no need to call <a href="erlang.html#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>. The Erlang code
│ │ │ -is in the sample file <code class="inline">next_perm.erl</code>.</p><p>The input is changed into a list of integers and sent to the driver.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="4960960548-1">(</span><span class="ss">next_perm</span><span class="p" data-group-id="4960960548-1">)</span><span class="p">.</span><span class="w">
│ │ │ +is in the sample file <code class="inline">next_perm.erl</code>.</p><p>The input is changed into a list of integers and sent to the driver.</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="3554768155-1">(</span><span class="ss">next_perm</span><span class="p" data-group-id="3554768155-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="4960960548-2">(</span><span class="p" data-group-id="4960960548-3">[</span><span class="ss">next_perm</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">prev_perm</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">load</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">all_perm</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="4960960548-3">]</span><span class="p" data-group-id="4960960548-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="3554768155-2">(</span><span class="p" data-group-id="3554768155-3">[</span><span class="ss">next_perm</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">prev_perm</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">load</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">all_perm</span><span class="p">/</span><span class="mi">1</span><span class="p" data-group-id="3554768155-3">]</span><span class="p" data-group-id="3554768155-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">load</span><span class="p" data-group-id="4960960548-4">(</span><span class="p" data-group-id="4960960548-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="4960960548-5">(</span><span class="ss">next_perm</span><span class="p" data-group-id="4960960548-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +</span><span class="nf">load</span><span class="p" data-group-id="3554768155-4">(</span><span class="p" data-group-id="3554768155-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="k">case</span><span class="w"> </span><span class="nf">whereis</span><span class="p" data-group-id="3554768155-5">(</span><span class="ss">next_perm</span><span class="p" data-group-id="3554768155-5">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │          </span><span class="ss">undefined</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="4960960548-6">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;next_perm&quot;</span><span class="p" data-group-id="4960960548-6">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │ +            </span><span class="k">case</span><span class="w"> </span><span class="nc">erl_ddll</span><span class="p">:</span><span class="nf">load_driver</span><span class="p" data-group-id="3554768155-6">(</span><span class="s">&quot;.&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;next_perm&quot;</span><span class="p" data-group-id="3554768155-6">)</span><span class="w"> </span><span class="k">of</span><span class="w">
│ │ │                  </span><span class="ss">ok</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -                </span><span class="p" data-group-id="4960960548-7">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="4960960548-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ -                </span><span class="n">E</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="4960960548-8">(</span><span class="n">E</span><span class="p" data-group-id="4960960548-8">)</span><span class="w">
│ │ │ +                </span><span class="p" data-group-id="3554768155-7">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="ss">already_loaded</span><span class="p" data-group-id="3554768155-7">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="ss">ok</span><span class="p">;</span><span class="w">
│ │ │ +                </span><span class="n">E</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="3554768155-8">(</span><span class="n">E</span><span class="p" data-group-id="3554768155-8">)</span><span class="w">
│ │ │              </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="4960960548-9">(</span><span class="p" data-group-id="4960960548-10">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;next_perm&quot;</span><span class="p" data-group-id="4960960548-10">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4960960548-11">[</span><span class="p" data-group-id="4960960548-11">]</span><span class="p" data-group-id="4960960548-9">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="nf">register</span><span class="p" data-group-id="4960960548-12">(</span><span class="ss">next_perm</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="4960960548-12">)</span><span class="p">;</span><span class="w">
│ │ │ +            </span><span class="n">Port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">open_port</span><span class="p" data-group-id="3554768155-9">(</span><span class="p" data-group-id="3554768155-10">{</span><span class="nb">spawn</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;next_perm&quot;</span><span class="p" data-group-id="3554768155-10">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3554768155-11">[</span><span class="p" data-group-id="3554768155-11">]</span><span class="p" data-group-id="3554768155-9">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">register</span><span class="p" data-group-id="3554768155-12">(</span><span class="ss">next_perm</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="3554768155-12">)</span><span class="p">;</span><span class="w">
│ │ │          </span><span class="p">_</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="ss">ok</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">list_to_integer_binaries</span><span class="p" data-group-id="4960960548-13">(</span><span class="n">L</span><span class="p" data-group-id="4960960548-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="4960960548-14">[</span><span class="p" data-group-id="4960960548-15">&lt;&lt;</span><span class="n">I</span><span class="p">:</span><span class="mi">32</span><span class="o">/</span><span class="ss">integer</span><span class="o">-</span><span class="ss">native</span><span class="p" data-group-id="4960960548-15">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">I</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="4960960548-14">]</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">list_to_integer_binaries</span><span class="p" data-group-id="3554768155-13">(</span><span class="n">L</span><span class="p" data-group-id="3554768155-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="3554768155-14">[</span><span class="p" data-group-id="3554768155-15">&lt;&lt;</span><span class="n">I</span><span class="p">:</span><span class="mi">32</span><span class="o">/</span><span class="ss">integer</span><span class="o">-</span><span class="ss">native</span><span class="p" data-group-id="3554768155-15">&gt;&gt;</span><span class="w"> </span><span class="p">||</span><span class="w"> </span><span class="n">I</span><span class="w"> </span><span class="o">&lt;-</span><span class="w"> </span><span class="n">L</span><span class="p" data-group-id="3554768155-14">]</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">next_perm</span><span class="p" data-group-id="4960960548-16">(</span><span class="n">L</span><span class="p" data-group-id="4960960548-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">next_perm</span><span class="p" data-group-id="4960960548-17">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4960960548-17">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">next_perm</span><span class="p" data-group-id="3554768155-16">(</span><span class="n">L</span><span class="p" data-group-id="3554768155-16">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">next_perm</span><span class="p" data-group-id="3554768155-17">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="3554768155-17">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">prev_perm</span><span class="p" data-group-id="4960960548-18">(</span><span class="n">L</span><span class="p" data-group-id="4960960548-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">next_perm</span><span class="p" data-group-id="4960960548-19">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="4960960548-19">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">prev_perm</span><span class="p" data-group-id="3554768155-18">(</span><span class="n">L</span><span class="p" data-group-id="3554768155-18">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">next_perm</span><span class="p" data-group-id="3554768155-19">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3554768155-19">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">next_perm</span><span class="p" data-group-id="4960960548-20">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Nxt</span><span class="p" data-group-id="4960960548-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nf">load</span><span class="p" data-group-id="4960960548-21">(</span><span class="p" data-group-id="4960960548-21">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">B</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">list_to_integer_binaries</span><span class="p" data-group-id="4960960548-22">(</span><span class="n">L</span><span class="p" data-group-id="4960960548-22">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">port_control</span><span class="p" data-group-id="4960960548-23">(</span><span class="ss">next_perm</span><span class="p">,</span><span class="w"> </span><span class="n">Nxt</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="4960960548-23">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">next_perm</span><span class="p" data-group-id="3554768155-20">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Nxt</span><span class="p" data-group-id="3554768155-20">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nf">load</span><span class="p" data-group-id="3554768155-21">(</span><span class="p" data-group-id="3554768155-21">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">B</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">list_to_integer_binaries</span><span class="p" data-group-id="3554768155-22">(</span><span class="n">L</span><span class="p" data-group-id="3554768155-22">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">port_control</span><span class="p" data-group-id="3554768155-23">(</span><span class="ss">next_perm</span><span class="p">,</span><span class="w"> </span><span class="n">Nxt</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p" data-group-id="3554768155-23">)</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │          </span><span class="n">Result</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Result</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">all_perm</span><span class="p" data-group-id="4960960548-24">(</span><span class="n">L</span><span class="p" data-group-id="4960960548-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">New</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">prev_perm</span><span class="p" data-group-id="4960960548-25">(</span><span class="n">L</span><span class="p" data-group-id="4960960548-25">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">all_perm</span><span class="p" data-group-id="4960960548-26">(</span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4960960548-27">[</span><span class="n">New</span><span class="p" data-group-id="4960960548-27">]</span><span class="p" data-group-id="4960960548-26">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">all_perm</span><span class="p" data-group-id="3554768155-24">(</span><span class="n">L</span><span class="p" data-group-id="3554768155-24">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">New</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">prev_perm</span><span class="p" data-group-id="3554768155-25">(</span><span class="n">L</span><span class="p" data-group-id="3554768155-25">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">all_perm</span><span class="p" data-group-id="3554768155-26">(</span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3554768155-27">[</span><span class="n">New</span><span class="p" data-group-id="3554768155-27">]</span><span class="p" data-group-id="3554768155-26">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">all_perm</span><span class="p" data-group-id="4960960548-28">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="4960960548-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">all_perm</span><span class="p" data-group-id="3554768155-28">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3554768155-28">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">all_perm</span><span class="p" data-group-id="4960960548-29">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Orig</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="4960960548-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">New</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">prev_perm</span><span class="p" data-group-id="4960960548-30">(</span><span class="n">L</span><span class="p" data-group-id="4960960548-30">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">all_perm</span><span class="p" data-group-id="4960960548-31">(</span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">Orig</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4960960548-32">[</span><span class="n">New</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="4960960548-32">]</span><span class="p" data-group-id="4960960548-31">)</span><span class="p">.</span></code></pre>
│ │ │ +</span><span class="nf">all_perm</span><span class="p" data-group-id="3554768155-29">(</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">Orig</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3554768155-29">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">New</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">prev_perm</span><span class="p" data-group-id="3554768155-30">(</span><span class="n">L</span><span class="p" data-group-id="3554768155-30">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">all_perm</span><span class="p" data-group-id="3554768155-31">(</span><span class="n">New</span><span class="p">,</span><span class="w"> </span><span class="n">Orig</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3554768155-32">[</span><span class="n">New</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="3554768155-32">]</span><span class="p" data-group-id="3554768155-31">)</span><span class="p">.</span></code></pre>
│ │ │  </div>
│ │ │  
│ │ │  <div class="bottom-actions" id="bottom-actions">
│ │ │    <div class="bottom-actions-item">
│ │ │  
│ │ │        <a href="tty.html" class="bottom-actions-button" rel="prev">
│ │ │          <span class="subheader">
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_cmd.html
│ │ │ @@ -149,26 +149,26 @@
│ │ │  runtime system, more specifically to the <code class="inline">init</code> system process, see <a href="init.html"><code class="inline">init</code></a>.</p><p>The <code class="inline">init</code> process itself interprets some of these flags, the <em>init flags</em>. It
│ │ │  also stores any remaining flags, the <em>user flags</em>. The latter can be retrieved
│ │ │  by calling <a href="init.html#get_argument/1"><code class="inline">init:get_argument/1</code></a>.</p><p>A small number of &quot;-&quot; flags exist, which now actually are emulator flags, see
│ │ │  the description below.</p></li><li><p>Plain arguments are not interpreted in any way. They are also stored by the
│ │ │  <code class="inline">init</code> process and can be retrieved by calling <a href="init.html#get_plain_arguments/0"><code class="inline">init:get_plain_arguments/0</code></a>.
│ │ │  Plain arguments can occur before the first flag, or after a <code class="inline">--</code> flag. Also,
│ │ │  the <code class="inline">-extra</code> flag causes everything that follows to become plain arguments.</p></li></ul><p><em>Examples:</em></p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl +W w -sname arnie +R 9 -s my_init -extra +bertie</span><span class="gp unselectable">
│ │ │ -(arnie@host)1&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_argument</span><span class="p" data-group-id="5946385359-1">(</span><span class="ss">sname</span><span class="p" data-group-id="5946385359-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5946385359-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="5946385359-3">[</span><span class="p" data-group-id="5946385359-4">[</span><span class="s">&quot;arnie&quot;</span><span class="p" data-group-id="5946385359-4">]</span><span class="p" data-group-id="5946385359-3">]</span><span class="p" data-group-id="5946385359-2">}</span><span class="gp unselectable">
│ │ │ -(arnie@host)2&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_plain_arguments</span><span class="p" data-group-id="5946385359-5">(</span><span class="p" data-group-id="5946385359-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5946385359-6">[</span><span class="s">&quot;+bertie&quot;</span><span class="p" data-group-id="5946385359-6">]</span></code></pre><p>Here <code class="inline">+W w</code> and <code class="inline">+R 9</code> are emulator flags. <code class="inline">-s my_init</code> is an init flag,
│ │ │ +(arnie@host)1&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_argument</span><span class="p" data-group-id="7721445623-1">(</span><span class="ss">sname</span><span class="p" data-group-id="7721445623-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7721445623-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="7721445623-3">[</span><span class="p" data-group-id="7721445623-4">[</span><span class="s">&quot;arnie&quot;</span><span class="p" data-group-id="7721445623-4">]</span><span class="p" data-group-id="7721445623-3">]</span><span class="p" data-group-id="7721445623-2">}</span><span class="gp unselectable">
│ │ │ +(arnie@host)2&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_plain_arguments</span><span class="p" data-group-id="7721445623-5">(</span><span class="p" data-group-id="7721445623-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7721445623-6">[</span><span class="s">&quot;+bertie&quot;</span><span class="p" data-group-id="7721445623-6">]</span></code></pre><p>Here <code class="inline">+W w</code> and <code class="inline">+R 9</code> are emulator flags. <code class="inline">-s my_init</code> is an init flag,
│ │ │  interpreted by <code class="inline">init</code>. <code class="inline">-sname arnie</code> is a user flag, stored by <code class="inline">init</code>. It is
│ │ │  read by Kernel and causes the Erlang runtime system to become distributed.
│ │ │  Finally, everything after <code class="inline">-extra</code> (that is, <code class="inline">+bertie</code>) is considered as plain
│ │ │  arguments.</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl -myflag 1</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_argument</span><span class="p" data-group-id="2497966887-1">(</span><span class="ss">myflag</span><span class="p" data-group-id="2497966887-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2497966887-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="2497966887-3">[</span><span class="p" data-group-id="2497966887-4">[</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="2497966887-4">]</span><span class="p" data-group-id="2497966887-3">]</span><span class="p" data-group-id="2497966887-2">}</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_plain_arguments</span><span class="p" data-group-id="2497966887-5">(</span><span class="p" data-group-id="2497966887-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2497966887-6">[</span><span class="p" data-group-id="2497966887-6">]</span></code></pre><p>Here the user flag <code class="inline">-myflag 1</code> is passed to and stored by the <code class="inline">init</code> process. It
│ │ │ +1&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_argument</span><span class="p" data-group-id="9121617207-1">(</span><span class="ss">myflag</span><span class="p" data-group-id="9121617207-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9121617207-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="9121617207-3">[</span><span class="p" data-group-id="9121617207-4">[</span><span class="s">&quot;1&quot;</span><span class="p" data-group-id="9121617207-4">]</span><span class="p" data-group-id="9121617207-3">]</span><span class="p" data-group-id="9121617207-2">}</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nc">init</span><span class="p">:</span><span class="nf">get_plain_arguments</span><span class="p" data-group-id="9121617207-5">(</span><span class="p" data-group-id="9121617207-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9121617207-6">[</span><span class="p" data-group-id="9121617207-6">]</span></code></pre><p>Here the user flag <code class="inline">-myflag 1</code> is passed to and stored by the <code class="inline">init</code> process. It
│ │ │  is a user-defined flag, presumably used by some user-defined application.</p><h2 id="flags" class="section-heading">
│ │ │    <a href="#flags" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Flags</span>
│ │ │  </h2>
│ │ │  <p>In the following list, init flags are marked &quot;(init flag)&quot;. Unless otherwise
│ │ │ @@ -700,15 +700,15 @@
│ │ │  processes) into a smaller set of schedulers when schedulers frequently run
│ │ │  out of work. When disabled, the frequency with which schedulers run out of
│ │ │  work is not taken into account by the load balancing logic.</p><p><code class="inline">+scl false</code> is similar to <a href="#%2Bsub"><code class="inline">+sub true</code></a>, but <code class="inline">+sub true</code>
│ │ │  also balances scheduler utilization between schedulers.</p></li><li><p><strong><code class="inline" id="+sct">+sct CpuTopology</code></strong> - Sets a user-defined CPU topology.
│ │ │  The user-defined CPU topology overrides
│ │ │  any automatically detected CPU topology. The CPU topology is used when
│ │ │  <a href="#%2Bsbt">binding schedulers to logical processors</a>. This option must be before
│ │ │ -<a href="#%2Bsbt"><code class="inline">+sbt</code></a> on the command-line.</p><pre><code class="makeup erlang" translate="no"><span class="o">&lt;</span><span class="n">Id</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="4195413730-1">(</span><span class="p" data-group-id="4195413730-1">)</span><span class="p">;</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="o">&lt;</span><span class="n">Id</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mi">65535</span><span class="w">
│ │ │ +<a href="#%2Bsbt"><code class="inline">+sbt</code></a> on the command-line.</p><pre><code class="makeup erlang" translate="no"><span class="o">&lt;</span><span class="n">Id</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="7035251920-1">(</span><span class="p" data-group-id="7035251920-1">)</span><span class="p">;</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="o">&lt;</span><span class="n">Id</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="mi">65535</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="n">IdRange</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">&lt;</span><span class="n">Id</span><span class="o">&gt;</span><span class="o">-</span><span class="o">&lt;</span><span class="n">Id</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="n">IdOrIdRange</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">&lt;</span><span class="n">Id</span><span class="o">&gt;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="o">&lt;</span><span class="n">IdRange</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">&lt;</span><span class="n">IdOrIdRange</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="n">IdOrIdRange</span><span class="o">&gt;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="o">&lt;</span><span class="n">IdOrIdRange</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="n">LogicalIds</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">L</span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="n">ThreadIds</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">T</span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">t</span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="n">CoreIds</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">C</span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">c</span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="n">ProcessorIds</span><span class="o">&gt;</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">P</span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">p</span><span class="o">&lt;</span><span class="n">IdList</span><span class="o">&gt;</span><span class="w">
│ │ │ @@ -733,30 +733,30 @@
│ │ │  node.</li><li><code class="inline">&lt;LogicalIds&gt;&lt;ThreadIds&gt;&lt;CoreIds&gt;&lt;NodeIds&gt;&lt;ProcessorIds&gt;</code>, that is, thread
│ │ │  is part of a core that is part of a NUMA node, which is part of a
│ │ │  processor.</li></ul><p>A CPU topology can consist of both processor external, and processor
│ │ │  internal NUMA nodes as long as each logical processor belongs to only one
│ │ │  NUMA node. If <code class="inline">&lt;ProcessorIds&gt;</code> is omitted, its default position is before
│ │ │  <code class="inline">&lt;NodeIds&gt;</code>. That is, the default is processor external NUMA nodes.</p><p>If a list of identifiers is used in an <code class="inline">&lt;IdDefs&gt;</code>:</p><ul><li><code class="inline">&lt;LogicalIds&gt;</code> must be a list of identifiers.</li><li>At least one other identifier type besides <code class="inline">&lt;LogicalIds&gt;</code> must also have a
│ │ │  list of identifiers.</li><li>All lists of identifiers must produce the same number of identifiers.</li></ul><p>A simple example. A single quad core processor can be described as follows:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl +sct L0-3c0-3</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="3545314767-1">(</span><span class="ss">cpu_topology</span><span class="p" data-group-id="3545314767-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3545314767-2">[</span><span class="p" data-group-id="3545314767-3">{</span><span class="ss">processor</span><span class="p">,</span><span class="p" data-group-id="3545314767-4">[</span><span class="p" data-group-id="3545314767-5">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="3545314767-6">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="3545314767-6">}</span><span class="p" data-group-id="3545314767-5">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="3545314767-7">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="3545314767-8">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="3545314767-8">}</span><span class="p" data-group-id="3545314767-7">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="3545314767-9">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="3545314767-10">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="3545314767-10">}</span><span class="p" data-group-id="3545314767-9">}</span><span class="p">,</span><span class="w">
│ │ │ -             </span><span class="p" data-group-id="3545314767-11">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="3545314767-12">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3545314767-12">}</span><span class="p" data-group-id="3545314767-11">}</span><span class="p" data-group-id="3545314767-4">]</span><span class="p" data-group-id="3545314767-3">}</span><span class="p" data-group-id="3545314767-2">]</span></code></pre><p>A more complicated example with two quad core processors, each processor in
│ │ │ +1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="1527163265-1">(</span><span class="ss">cpu_topology</span><span class="p" data-group-id="1527163265-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1527163265-2">[</span><span class="p" data-group-id="1527163265-3">{</span><span class="ss">processor</span><span class="p">,</span><span class="p" data-group-id="1527163265-4">[</span><span class="p" data-group-id="1527163265-5">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="1527163265-6">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="1527163265-6">}</span><span class="p" data-group-id="1527163265-5">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="1527163265-7">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="1527163265-8">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="1527163265-8">}</span><span class="p" data-group-id="1527163265-7">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="1527163265-9">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="1527163265-10">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1527163265-10">}</span><span class="p" data-group-id="1527163265-9">}</span><span class="p">,</span><span class="w">
│ │ │ +             </span><span class="p" data-group-id="1527163265-11">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="1527163265-12">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1527163265-12">}</span><span class="p" data-group-id="1527163265-11">}</span><span class="p" data-group-id="1527163265-4">]</span><span class="p" data-group-id="1527163265-3">}</span><span class="p" data-group-id="1527163265-2">]</span></code></pre><p>A more complicated example with two quad core processors, each processor in
│ │ │  its own NUMA node. The ordering of logical processors is a bit weird. This
│ │ │  to give a better example of identifier lists:</p><pre><code class="makeup erlang" translate="no"><span class="c1">% erl +sct L0-1,3-2c0-3p0N0:L7,4,6-5c0-3p1N1</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="8185268458-1">(</span><span class="ss">cpu_topology</span><span class="p" data-group-id="8185268458-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8185268458-2">[</span><span class="p" data-group-id="8185268458-3">{</span><span class="nb">node</span><span class="p">,</span><span class="p" data-group-id="8185268458-4">[</span><span class="p" data-group-id="8185268458-5">{</span><span class="ss">processor</span><span class="p">,</span><span class="p" data-group-id="8185268458-6">[</span><span class="p" data-group-id="8185268458-7">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-8">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="8185268458-8">}</span><span class="p" data-group-id="8185268458-7">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="8185268458-9">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-10">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="8185268458-10">}</span><span class="p" data-group-id="8185268458-9">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="8185268458-11">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-12">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8185268458-12">}</span><span class="p" data-group-id="8185268458-11">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="8185268458-13">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-14">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="8185268458-14">}</span><span class="p" data-group-id="8185268458-13">}</span><span class="p" data-group-id="8185268458-6">]</span><span class="p" data-group-id="8185268458-5">}</span><span class="p" data-group-id="8185268458-4">]</span><span class="p" data-group-id="8185268458-3">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8185268458-15">{</span><span class="nb">node</span><span class="p">,</span><span class="p" data-group-id="8185268458-16">[</span><span class="p" data-group-id="8185268458-17">{</span><span class="ss">processor</span><span class="p">,</span><span class="p" data-group-id="8185268458-18">[</span><span class="p" data-group-id="8185268458-19">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-20">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="8185268458-20">}</span><span class="p" data-group-id="8185268458-19">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="8185268458-21">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-22">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="8185268458-22">}</span><span class="p" data-group-id="8185268458-21">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="8185268458-23">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-24">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8185268458-24">}</span><span class="p" data-group-id="8185268458-23">}</span><span class="p">,</span><span class="w">
│ │ │ -                    </span><span class="p" data-group-id="8185268458-25">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="8185268458-26">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8185268458-26">}</span><span class="p" data-group-id="8185268458-25">}</span><span class="p" data-group-id="8185268458-18">]</span><span class="p" data-group-id="8185268458-17">}</span><span class="p" data-group-id="8185268458-16">]</span><span class="p" data-group-id="8185268458-15">}</span><span class="p" data-group-id="8185268458-2">]</span></code></pre><p>As long as real identifiers are correct, it is OK to pass a CPU topology
│ │ │ +1&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="7775195563-1">(</span><span class="ss">cpu_topology</span><span class="p" data-group-id="7775195563-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7775195563-2">[</span><span class="p" data-group-id="7775195563-3">{</span><span class="nb">node</span><span class="p">,</span><span class="p" data-group-id="7775195563-4">[</span><span class="p" data-group-id="7775195563-5">{</span><span class="ss">processor</span><span class="p">,</span><span class="p" data-group-id="7775195563-6">[</span><span class="p" data-group-id="7775195563-7">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-8">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="7775195563-8">}</span><span class="p" data-group-id="7775195563-7">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="7775195563-9">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-10">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="7775195563-10">}</span><span class="p" data-group-id="7775195563-9">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="7775195563-11">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-12">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7775195563-12">}</span><span class="p" data-group-id="7775195563-11">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="7775195563-13">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-14">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7775195563-14">}</span><span class="p" data-group-id="7775195563-13">}</span><span class="p" data-group-id="7775195563-6">]</span><span class="p" data-group-id="7775195563-5">}</span><span class="p" data-group-id="7775195563-4">]</span><span class="p" data-group-id="7775195563-3">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="7775195563-15">{</span><span class="nb">node</span><span class="p">,</span><span class="p" data-group-id="7775195563-16">[</span><span class="p" data-group-id="7775195563-17">{</span><span class="ss">processor</span><span class="p">,</span><span class="p" data-group-id="7775195563-18">[</span><span class="p" data-group-id="7775195563-19">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-20">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">7</span><span class="p" data-group-id="7775195563-20">}</span><span class="p" data-group-id="7775195563-19">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="7775195563-21">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-22">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="7775195563-22">}</span><span class="p" data-group-id="7775195563-21">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="7775195563-23">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-24">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="7775195563-24">}</span><span class="p" data-group-id="7775195563-23">}</span><span class="p">,</span><span class="w">
│ │ │ +                    </span><span class="p" data-group-id="7775195563-25">{</span><span class="ss">core</span><span class="p">,</span><span class="p" data-group-id="7775195563-26">{</span><span class="ss">logical</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7775195563-26">}</span><span class="p" data-group-id="7775195563-25">}</span><span class="p" data-group-id="7775195563-18">]</span><span class="p" data-group-id="7775195563-17">}</span><span class="p" data-group-id="7775195563-16">]</span><span class="p" data-group-id="7775195563-15">}</span><span class="p" data-group-id="7775195563-2">]</span></code></pre><p>As long as real identifiers are correct, it is OK to pass a CPU topology
│ │ │  that is not a correct description of the CPU topology. When used with care
│ │ │  this can be very useful. This to trick the emulator to bind its schedulers
│ │ │  as you want. For example, if you want to run multiple Erlang runtime systems
│ │ │  on the same machine, you want to reduce the number of schedulers used and
│ │ │  manipulate the CPU topology so that they bind to different logical CPUs. An
│ │ │  example, with two Erlang runtime systems on a quad core machine:</p><pre><code class="text">% erl +sct L0-3c0-3 +sbt db +S3:2 -detached -noinput -noshell -sname one
│ │ │  % erl +sct L3-0c0-3 +sbt db +S3:2 -detached -noinput -noshell -sname two</code></pre><p>In this example, each runtime system have two schedulers each online, and
│ │ │ @@ -923,18 +923,18 @@
│ │ │  </h2>
│ │ │  <p>The standard Erlang/OTP system can be reconfigured to change the default
│ │ │  behavior on startup.</p><ul><li><p><strong>The <code class="inline">.erlang</code> startup file</strong> - When Erlang/OTP is started, the system
│ │ │  searches for a file named <code class="inline">.erlang</code> in the
│ │ │  <a href="init.html#home">user's home directory</a> and then
│ │ │  <a href="../../../lib/stdlib-6.2.2.2/doc/html/filename.html#user_config"><code class="inline">filename:basedir(user_config, &quot;erlang&quot;)</code></a>.</p><p>If an <code class="inline">.erlang</code> file is found, it is assumed to contain valid Erlang
│ │ │  expressions. These expressions are evaluated as if they were input to the
│ │ │ -shell.</p><p>A typical <code class="inline">.erlang</code> file contains a set of search paths, for example:</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5336915520-1">(</span><span class="s">&quot;executing user profile in $HOME/.erlang\n&quot;</span><span class="p">,</span><span class="p" data-group-id="5336915520-2">[</span><span class="p" data-group-id="5336915520-2">]</span><span class="p" data-group-id="5336915520-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nc">code</span><span class="p">:</span><span class="nf">add_path</span><span class="p" data-group-id="5336915520-3">(</span><span class="s">&quot;/home/calvin/test/ebin&quot;</span><span class="p" data-group-id="5336915520-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nc">code</span><span class="p">:</span><span class="nf">add_path</span><span class="p" data-group-id="5336915520-4">(</span><span class="s">&quot;/home/hobbes/bigappl-1.2/ebin&quot;</span><span class="p" data-group-id="5336915520-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5336915520-5">(</span><span class="s">&quot;.erlang rc finished\n&quot;</span><span class="p">,</span><span class="p" data-group-id="5336915520-6">[</span><span class="p" data-group-id="5336915520-6">]</span><span class="p" data-group-id="5336915520-5">)</span><span class="p">.</span></code></pre></li><li><p><strong>user_default</strong> and <strong>shell_default</strong> - Functions in the shell that are not
│ │ │ +shell.</p><p>A typical <code class="inline">.erlang</code> file contains a set of search paths, for example:</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0903335101-1">(</span><span class="s">&quot;executing user profile in $HOME/.erlang\n&quot;</span><span class="p">,</span><span class="p" data-group-id="0903335101-2">[</span><span class="p" data-group-id="0903335101-2">]</span><span class="p" data-group-id="0903335101-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nc">code</span><span class="p">:</span><span class="nf">add_path</span><span class="p" data-group-id="0903335101-3">(</span><span class="s">&quot;/home/calvin/test/ebin&quot;</span><span class="p" data-group-id="0903335101-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nc">code</span><span class="p">:</span><span class="nf">add_path</span><span class="p" data-group-id="0903335101-4">(</span><span class="s">&quot;/home/hobbes/bigappl-1.2/ebin&quot;</span><span class="p" data-group-id="0903335101-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0903335101-5">(</span><span class="s">&quot;.erlang rc finished\n&quot;</span><span class="p">,</span><span class="p" data-group-id="0903335101-6">[</span><span class="p" data-group-id="0903335101-6">]</span><span class="p" data-group-id="0903335101-5">)</span><span class="p">.</span></code></pre></li><li><p><strong>user_default</strong> and <strong>shell_default</strong> - Functions in the shell that are not
│ │ │  prefixed by a module name are assumed to be functional objects (funs),
│ │ │  built-in functions (BIFs), or belong to the module <code class="inline">user_default</code> or
│ │ │  <code class="inline">shell_default</code>.</p><p>To include private shell commands, define them in a module <code class="inline">user_default</code> and
│ │ │  add the following argument as the first line in the <code class="inline">.erlang</code> file:</p><pre><code class="text">code:load_abs(&quot;..../user_default&quot;).</code></pre></li><li><p><strong>erl</strong> - If the contents of <code class="inline">.erlang</code> are changed and a private version of
│ │ │  <code class="inline">user_default</code> is defined, the Erlang/OTP environment can be customized. More
│ │ │  powerful changes can be made by supplying command-line arguments in the
│ │ │  startup script <code class="inline">erl</code>. For more information, see <a href="init.html"><code class="inline">init</code></a>.</p></li></ul><h2 id="see-also" class="section-heading">
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_dist_protocol.html
│ │ │ @@ -252,32 +252,32 @@
│ │ │  ---
│ │ │  sequenceDiagram
│ │ │      participant client as Client (or Node)
│ │ │      participant EPMD
│ │ │      
│ │ │      client -&gt;&gt; EPMD: NAMES_REQ
│ │ │      EPMD --&gt;&gt; client: NAMES_RESP</code></pre><table><thead><tr><th style="text-align: left;">1</th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">110</code></td></tr></tbody></table><p><em>Table: NAMES_REQ (110)</em></p><p>The response for a <code class="inline">NAMES_REQ</code> is as follows:</p><table><thead><tr><th style="text-align: left;">4</th><th style="text-align: left;"></th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">EPMDPortNo</code></td><td style="text-align: left;"><code class="inline">NodeInfo*</code></td></tr></tbody></table><p><em>Table: NAMES_RESP</em></p><p><code class="inline">NodeInfo</code> is a string written for each active node. When all <code class="inline">NodeInfo</code> has
│ │ │ -been written the connection is closed by the EPMD.</p><p><code class="inline">NodeInfo</code> is, as expressed in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="8657286236-1">(</span><span class="s">&quot;name ~ts at port </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8657286236-2">[</span><span class="n">NodeName</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="8657286236-2">]</span><span class="p" data-group-id="8657286236-1">)</span><span class="p">.</span></code></pre><h3 id="dump-all-data-from-epmd" class="section-heading">
│ │ │ +been written the connection is closed by the EPMD.</p><p><code class="inline">NodeInfo</code> is, as expressed in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5846924653-1">(</span><span class="s">&quot;name ~ts at port </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5846924653-2">[</span><span class="n">NodeName</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p" data-group-id="5846924653-2">]</span><span class="p" data-group-id="5846924653-1">)</span><span class="p">.</span></code></pre><h3 id="dump-all-data-from-epmd" class="section-heading">
│ │ │    <a href="#dump-all-data-from-epmd" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Dump All Data from EPMD</span>
│ │ │  </h3>
│ │ │  <p>This request is not really used, it is to be regarded as a debug feature.</p><pre><code class="mermaid">---
│ │ │  title: Dump All Data from EPMD
│ │ │  ---
│ │ │  sequenceDiagram
│ │ │      participant client as Client (or Node)
│ │ │      participant EPMD
│ │ │      
│ │ │      client -&gt;&gt; EPMD: DUMP_REQ
│ │ │      EPMD --&gt;&gt; client: DUMP_RESP</code></pre><table><thead><tr><th style="text-align: left;">1</th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">100</code></td></tr></tbody></table><p><em>Table: DUMP_REQ</em></p><p>The response for a <code class="inline">DUMP_REQ</code> is as follows:</p><table><thead><tr><th style="text-align: left;">4</th><th style="text-align: left;"></th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">EPMDPortNo</code></td><td style="text-align: left;"><code class="inline">NodeInfo*</code></td></tr></tbody></table><p><em>Table: DUMP_RESP</em></p><p><code class="inline">NodeInfo</code> is a string written for each node kept in the EPMD. When all
│ │ │ -<code class="inline">NodeInfo</code> has been written the connection is closed by the EPMD.</p><p><code class="inline">NodeInfo</code> is, as expressed in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3320190260-1">(</span><span class="s">&quot;active name     ~ts at port </span><span class="si">~p</span><span class="s">, fd = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="3320190260-2">[</span><span class="n">NodeName</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="3320190260-2">]</span><span class="p" data-group-id="3320190260-1">)</span><span class="p">.</span></code></pre><p>or</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="0083321753-1">(</span><span class="s">&quot;old/unused name ~ts at port </span><span class="si">~p</span><span class="s">, fd = </span><span class="si">~p</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ -          </span><span class="p" data-group-id="0083321753-2">[</span><span class="n">NodeName</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="0083321753-2">]</span><span class="p" data-group-id="0083321753-1">)</span><span class="p">.</span></code></pre><h3 id="kill-epmd" class="section-heading">
│ │ │ +<code class="inline">NodeInfo</code> has been written the connection is closed by the EPMD.</p><p><code class="inline">NodeInfo</code> is, as expressed in Erlang:</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3277956291-1">(</span><span class="s">&quot;active name     ~ts at port </span><span class="si">~p</span><span class="s">, fd = </span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="3277956291-2">[</span><span class="n">NodeName</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="3277956291-2">]</span><span class="p" data-group-id="3277956291-1">)</span><span class="p">.</span></code></pre><p>or</p><pre><code class="makeup erlang" translate="no"><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1026178012-1">(</span><span class="s">&quot;old/unused name ~ts at port </span><span class="si">~p</span><span class="s">, fd = </span><span class="si">~p</span><span class="s"> </span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w">
│ │ │ +          </span><span class="p" data-group-id="1026178012-2">[</span><span class="n">NodeName</span><span class="p">,</span><span class="w"> </span><span class="n">Port</span><span class="p">,</span><span class="w"> </span><span class="n">Fd</span><span class="p" data-group-id="1026178012-2">]</span><span class="p" data-group-id="1026178012-1">)</span><span class="p">.</span></code></pre><h3 id="kill-epmd" class="section-heading">
│ │ │    <a href="#kill-epmd" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Kill EPMD</span>
│ │ │  </h3>
│ │ │  <p>This request kills the running EPMD. It is almost never used.</p><pre><code class="mermaid">---
│ │ │  title: Kill EPMD
│ │ │ @@ -407,54 +407,54 @@
│ │ │  received from <code class="inline">A</code> is correct and generates a digest from the challenge
│ │ │  received from <code class="inline">A</code>. The digest is then sent to <code class="inline">A</code>. The message is as follows:</p><table><thead><tr><th style="text-align: left;">1</th><th style="text-align: left;">16</th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">'a'</code></td><td style="text-align: left;"><code class="inline">Digest</code></td></tr></tbody></table><p><em>Table: The challenge_ack message</em></p><p><code class="inline">Digest</code> is the digest calculated by <code class="inline">B</code> for <code class="inline">A</code>'s challenge.</p></li><li><p><strong>7) check</strong> - <code class="inline">A</code> checks the digest from <code class="inline">B</code> and the connection is up.</p></li></ul><h3 id="semigraphic-view" class="section-heading">
│ │ │    <a href="#semigraphic-view" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">Semigraphic View</span>
│ │ │  </h3>
│ │ │ -<pre><code class="makeup erlang" translate="no"><span class="n">A</span><span class="w"> </span><span class="p" data-group-id="4483065113-1">(</span><span class="ss">initiator</span><span class="p" data-group-id="4483065113-1">)</span><span class="w">                                      </span><span class="n">B</span><span class="w"> </span><span class="p" data-group-id="4483065113-2">(</span><span class="ss">acceptor</span><span class="p" data-group-id="4483065113-2">)</span><span class="w">
│ │ │ +<pre><code class="makeup erlang" translate="no"><span class="n">A</span><span class="w"> </span><span class="p" data-group-id="5091001355-1">(</span><span class="ss">initiator</span><span class="p" data-group-id="5091001355-1">)</span><span class="w">                                      </span><span class="n">B</span><span class="w"> </span><span class="p" data-group-id="5091001355-2">(</span><span class="ss">acceptor</span><span class="p" data-group-id="5091001355-2">)</span><span class="w">
│ │ │  
│ │ │  </span><span class="n">TCP</span><span class="w"> </span><span class="ss">connect</span><span class="w"> </span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">&gt;</span><span class="w">
│ │ │                                                     </span><span class="n">TCP</span><span class="w"> </span><span class="ss">accept</span><span class="w">
│ │ │  
│ │ │  </span><span class="ss">send_name</span><span class="w"> </span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">&gt;</span><span class="w">
│ │ │                                                     </span><span class="ss">recv_name</span><span class="w">
│ │ │  
│ │ │    </span><span class="o">&lt;-</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">-</span><span class="w"> </span><span class="ss">send_status</span><span class="w">
│ │ │  </span><span class="nf">recv_status</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4483065113-3">(</span><span class="k">if</span><span class="w"> </span><span class="ss">status</span><span class="w"> </span><span class="ss">was</span><span class="w"> </span><span class="ss">&#39;alive&#39;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5091001355-3">(</span><span class="k">if</span><span class="w"> </span><span class="ss">status</span><span class="w"> </span><span class="ss">was</span><span class="w"> </span><span class="ss">&#39;alive&#39;</span><span class="w">
│ │ │   </span><span class="ss">send_status</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                                                   </span><span class="ss">recv_status</span><span class="p" data-group-id="4483065113-3">)</span><span class="w">
│ │ │ +                                                   </span><span class="ss">recv_status</span><span class="p" data-group-id="5091001355-3">)</span><span class="w">
│ │ │  
│ │ │ -                          </span><span class="p" data-group-id="4483065113-4">(</span><span class="n">ChB</span><span class="p" data-group-id="4483065113-4">)</span><span class="w">                      </span><span class="n">ChB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_challenge</span><span class="p" data-group-id="4483065113-5">(</span><span class="p" data-group-id="4483065113-5">)</span><span class="w">
│ │ │ +                          </span><span class="p" data-group-id="5091001355-4">(</span><span class="n">ChB</span><span class="p" data-group-id="5091001355-4">)</span><span class="w">                      </span><span class="n">ChB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_challenge</span><span class="p" data-group-id="5091001355-5">(</span><span class="p" data-group-id="5091001355-5">)</span><span class="w">
│ │ │    </span><span class="o">&lt;-</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">-</span><span class="w"> </span><span class="ss">send_challenge</span><span class="w">
│ │ │  </span><span class="nf">recv_challenge</span><span class="w">
│ │ │  
│ │ │ -</span><span class="p" data-group-id="4483065113-6">(</span><span class="k">if</span><span class="w"> </span><span class="ss">old</span><span class="w"> </span><span class="ss">send_name</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5091001355-6">(</span><span class="k">if</span><span class="w"> </span><span class="ss">old</span><span class="w"> </span><span class="ss">send_name</span><span class="w">
│ │ │   </span><span class="ss">send_complement</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                                                   </span><span class="ss">recv_complement</span><span class="p" data-group-id="4483065113-6">)</span><span class="w">
│ │ │ +                                                   </span><span class="ss">recv_complement</span><span class="p" data-group-id="5091001355-6">)</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">ChA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_challenge</span><span class="p" data-group-id="4483065113-7">(</span><span class="p" data-group-id="4483065113-7">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">OCA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">out_cookie</span><span class="p" data-group-id="4483065113-8">(</span><span class="n">B</span><span class="p" data-group-id="4483065113-8">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">DiA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_digest</span><span class="p" data-group-id="4483065113-9">(</span><span class="n">ChB</span><span class="p">,</span><span class="w"> </span><span class="n">OCA</span><span class="p" data-group-id="4483065113-9">)</span><span class="w">
│ │ │ -                          </span><span class="p" data-group-id="4483065113-10">(</span><span class="n">ChA</span><span class="p">,</span><span class="w"> </span><span class="n">DiA</span><span class="p" data-group-id="4483065113-10">)</span><span class="w">
│ │ │ +</span><span class="n">ChA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_challenge</span><span class="p" data-group-id="5091001355-7">(</span><span class="p" data-group-id="5091001355-7">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">OCA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">out_cookie</span><span class="p" data-group-id="5091001355-8">(</span><span class="n">B</span><span class="p" data-group-id="5091001355-8">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">DiA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_digest</span><span class="p" data-group-id="5091001355-9">(</span><span class="n">ChB</span><span class="p">,</span><span class="w"> </span><span class="n">OCA</span><span class="p" data-group-id="5091001355-9">)</span><span class="w">
│ │ │ +                          </span><span class="p" data-group-id="5091001355-10">(</span><span class="n">ChA</span><span class="p">,</span><span class="w"> </span><span class="n">DiA</span><span class="p" data-group-id="5091001355-10">)</span><span class="w">
│ │ │  </span><span class="ss">send_challenge_reply</span><span class="w"> </span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="p">-&gt;</span><span class="w">
│ │ │                                                     </span><span class="ss">recv_challenge_reply</span><span class="w">
│ │ │ -                                                   </span><span class="n">ICB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">in_cookie</span><span class="p" data-group-id="4483065113-11">(</span><span class="n">A</span><span class="p" data-group-id="4483065113-11">)</span><span class="p">,</span><span class="w">
│ │ │ +                                                   </span><span class="n">ICB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">in_cookie</span><span class="p" data-group-id="5091001355-11">(</span><span class="n">A</span><span class="p" data-group-id="5091001355-11">)</span><span class="p">,</span><span class="w">
│ │ │                                                     </span><span class="nc">check</span><span class="p">:</span><span class="w">
│ │ │ -                                                   </span><span class="n">DiA</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nf">gen_digest</span><span class="w"> </span><span class="p" data-group-id="4483065113-12">(</span><span class="n">ChB</span><span class="p">,</span><span class="w"> </span><span class="n">ICB</span><span class="p" data-group-id="4483065113-12">)</span><span class="o">?</span><span class="w">
│ │ │ +                                                   </span><span class="n">DiA</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nf">gen_digest</span><span class="w"> </span><span class="p" data-group-id="5091001355-12">(</span><span class="n">ChB</span><span class="p">,</span><span class="w"> </span><span class="n">ICB</span><span class="p" data-group-id="5091001355-12">)</span><span class="o">?</span><span class="w">
│ │ │  </span><span class="w">                                                   </span><span class="p">-</span><span class="w"> </span><span class="na">if</span><span class="w"> </span><span class="n">OK</span><span class="p">:</span><span class="w">
│ │ │ -                                                    </span><span class="n">OCB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">out_cookie</span><span class="p" data-group-id="4483065113-13">(</span><span class="n">A</span><span class="p" data-group-id="4483065113-13">)</span><span class="p">,</span><span class="w">
│ │ │ -                                                    </span><span class="n">DiB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_digest</span><span class="w"> </span><span class="p" data-group-id="4483065113-14">(</span><span class="n">ChA</span><span class="p">,</span><span class="w"> </span><span class="n">OCB</span><span class="p" data-group-id="4483065113-14">)</span><span class="w">
│ │ │ -                          </span><span class="p" data-group-id="4483065113-15">(</span><span class="n">DiB</span><span class="p" data-group-id="4483065113-15">)</span><span class="w">
│ │ │ +                                                    </span><span class="n">OCB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">out_cookie</span><span class="p" data-group-id="5091001355-13">(</span><span class="n">A</span><span class="p" data-group-id="5091001355-13">)</span><span class="p">,</span><span class="w">
│ │ │ +                                                    </span><span class="n">DiB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">gen_digest</span><span class="w"> </span><span class="p" data-group-id="5091001355-14">(</span><span class="n">ChA</span><span class="p">,</span><span class="w"> </span><span class="n">OCB</span><span class="p" data-group-id="5091001355-14">)</span><span class="w">
│ │ │ +                          </span><span class="p" data-group-id="5091001355-15">(</span><span class="n">DiB</span><span class="p" data-group-id="5091001355-15">)</span><span class="w">
│ │ │    </span><span class="o">&lt;-</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="o">--</span><span class="w"> </span><span class="ss">send_challenge_ack</span><span class="w">
│ │ │  </span><span class="ss">recv_challenge_ack</span><span class="w">                                  </span><span class="n">DONE</span><span class="w">
│ │ │ -</span><span class="n">ICA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">in_cookie</span><span class="p" data-group-id="4483065113-16">(</span><span class="n">B</span><span class="p" data-group-id="4483065113-16">)</span><span class="p">,</span><span class="w">                                </span><span class="o">-</span><span class="w"> </span><span class="nc">else</span><span class="p">:</span><span class="w">
│ │ │ +</span><span class="n">ICA</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">in_cookie</span><span class="p" data-group-id="5091001355-16">(</span><span class="n">B</span><span class="p" data-group-id="5091001355-16">)</span><span class="p">,</span><span class="w">                                </span><span class="o">-</span><span class="w"> </span><span class="nc">else</span><span class="p">:</span><span class="w">
│ │ │  </span><span class="nc">check</span><span class="p">:</span><span class="w">                                              </span><span class="n">CLOSE</span><span class="w">
│ │ │ -</span><span class="n">DiB</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nf">gen_digest</span><span class="p" data-group-id="4483065113-17">(</span><span class="n">ChA</span><span class="p">,</span><span class="w"> </span><span class="n">ICA</span><span class="p" data-group-id="4483065113-17">)</span><span class="o">?</span><span class="w">
│ │ │ +</span><span class="n">DiB</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nf">gen_digest</span><span class="p" data-group-id="5091001355-17">(</span><span class="n">ChA</span><span class="p">,</span><span class="w"> </span><span class="n">ICA</span><span class="p" data-group-id="5091001355-17">)</span><span class="o">?</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="w"> </span><span class="na">if</span><span class="w"> </span><span class="n">OK</span><span class="p">:</span><span class="w">
│ │ │   </span><span class="n">DONE</span><span class="w">
│ │ │  </span><span class="p">-</span><span class="w"> </span><span class="na">else</span><span class="p">:</span><span class="w">
│ │ │   </span><span class="n">CLOSE</span></code></pre><p><a href="" id="dflags"></a></p><h3 id="distribution-flags" class="section-heading">
│ │ │    <a href="#distribution-flags" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_ext_dist.html
│ │ │ @@ -436,15 +436,15 @@
│ │ │    </a>
│ │ │    <span class="text">SMALL_BIG_EXT</span>
│ │ │  </h2>
│ │ │  <table><thead><tr><th style="text-align: left;">1</th><th style="text-align: left;">1</th><th style="text-align: left;">1</th><th style="text-align: left;">n</th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">110</code></td><td style="text-align: left;"><code class="inline">n</code></td><td style="text-align: left;"><code class="inline">Sign</code></td><td style="text-align: left;"><code class="inline">d(0)</code> ... <code class="inline">d(n-1)</code></td></tr></tbody></table><p>Bignums are stored in unary form with a <code class="inline">Sign</code> byte, that is, 0 if the bignum is
│ │ │  positive and 1 if it is negative. The digits are stored with the least
│ │ │  significant byte stored first. To calculate the integer, the following formula
│ │ │  can be used:</p><pre><code class="makeup erlang" translate="no"><span class="n">B</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">256</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5021826598-1">(</span><span class="ss">d0</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="mi">0</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">d1</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">d2</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="mi">2</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="nf">d</span><span class="p" data-group-id="5021826598-2">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="5021826598-2">)</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="p" data-group-id="5021826598-3">(</span><span class="ss">n</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="5021826598-3">)</span><span class="p" data-group-id="5021826598-1">)</span></code></pre><h2 id="large_big_ext" class="section-heading">
│ │ │ +</span><span class="p" data-group-id="9273972563-1">(</span><span class="ss">d0</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="mi">0</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">d1</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="mi">1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="ss">d2</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="mi">2</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="w"> </span><span class="nf">d</span><span class="p" data-group-id="9273972563-2">(</span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="9273972563-2">)</span><span class="o">*</span><span class="n">B</span><span class="err">^</span><span class="p" data-group-id="9273972563-3">(</span><span class="ss">n</span><span class="o">-</span><span class="mi">1</span><span class="p" data-group-id="9273972563-3">)</span><span class="p" data-group-id="9273972563-1">)</span></code></pre><h2 id="large_big_ext" class="section-heading">
│ │ │    <a href="#large_big_ext" class="hover-link">
│ │ │      <i class="ri-link-m" aria-hidden="true"></i>
│ │ │    </a>
│ │ │    <span class="text">LARGE_BIG_EXT</span>
│ │ │  </h2>
│ │ │  <table><thead><tr><th style="text-align: left;">1</th><th style="text-align: left;">4</th><th style="text-align: left;">1</th><th style="text-align: left;">n</th></tr></thead><tbody><tr><td style="text-align: left;"><code class="inline">111</code></td><td style="text-align: left;"><code class="inline">n</code></td><td style="text-align: left;"><code class="inline">Sign</code></td><td style="text-align: left;"><code class="inline">d(0)</code> ... <code class="inline">d(n-1)</code></td></tr></tbody></table><p>Same as <a href="erl_ext_dist.html#small_big_ext"><code class="inline">SMALL_BIG_EXT</code></a> except that the length
│ │ │  field is an unsigned 4 byte integer.</p><h2 id="reference_ext-deprecated" class="section-heading">
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_nif.html
│ │ │ @@ -161,27 +161,27 @@
│ │ │  }
│ │ │  
│ │ │  static ErlNifFunc nif_funcs[] =
│ │ │  {
│ │ │      {&quot;hello&quot;, 0, hello}
│ │ │  };
│ │ │  
│ │ │ -ERL_NIF_INIT(niftest,nif_funcs,NULL,NULL,NULL,NULL)</code></pre><p>The Erlang module can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="0728212148-1">(</span><span class="ss">niftest</span><span class="p" data-group-id="0728212148-1">)</span><span class="p">.</span><span class="w">
│ │ │ +ERL_NIF_INIT(niftest,nif_funcs,NULL,NULL,NULL,NULL)</code></pre><p>The Erlang module can look as follows:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9756866119-1">(</span><span class="ss">niftest</span><span class="p" data-group-id="9756866119-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="0728212148-2">(</span><span class="p" data-group-id="0728212148-3">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">hello</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0728212148-3">]</span><span class="p" data-group-id="0728212148-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9756866119-2">(</span><span class="p" data-group-id="9756866119-3">[</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">hello</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9756866119-3">]</span><span class="p" data-group-id="9756866119-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">nifs</span><span class="p" data-group-id="0728212148-4">(</span><span class="p" data-group-id="0728212148-5">[</span><span class="ss">hello</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0728212148-5">]</span><span class="p" data-group-id="0728212148-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">nifs</span><span class="p" data-group-id="9756866119-4">(</span><span class="p" data-group-id="9756866119-5">[</span><span class="ss">hello</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9756866119-5">]</span><span class="p" data-group-id="9756866119-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="0728212148-6">(</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="0728212148-6">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">on_load</span><span class="p" data-group-id="9756866119-6">(</span><span class="ss">init</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="9756866119-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">init</span><span class="p" data-group-id="0728212148-7">(</span><span class="p" data-group-id="0728212148-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -      </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="0728212148-8">(</span><span class="s">&quot;./niftest&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="0728212148-8">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">init</span><span class="p" data-group-id="9756866119-7">(</span><span class="p" data-group-id="9756866119-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +      </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="9756866119-8">(</span><span class="s">&quot;./niftest&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="9756866119-8">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">hello</span><span class="p" data-group-id="0728212148-9">(</span><span class="p" data-group-id="0728212148-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -      </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="0728212148-10">(</span><span class="s">&quot;NIF library not loaded&quot;</span><span class="p" data-group-id="0728212148-10">)</span><span class="p">.</span></code></pre><p>Compile and test can look as follows (on Linux):</p><pre><code class="text">$&gt; gcc -fPIC -shared -o niftest.so niftest.c -I $ERL_ROOT/usr/include/
│ │ │ +</span><span class="nf">hello</span><span class="p" data-group-id="9756866119-9">(</span><span class="p" data-group-id="9756866119-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +      </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">nif_error</span><span class="p" data-group-id="9756866119-10">(</span><span class="s">&quot;NIF library not loaded&quot;</span><span class="p" data-group-id="9756866119-10">)</span><span class="p">.</span></code></pre><p>Compile and test can look as follows (on Linux):</p><pre><code class="text">$&gt; gcc -fPIC -shared -o niftest.so niftest.c -I $ERL_ROOT/usr/include/
│ │ │  $&gt; erl
│ │ │  
│ │ │  1&gt; c(niftest).
│ │ │  {ok,niftest}
│ │ │  2&gt; niftest:hello().
│ │ │  &quot;Hello world!&quot;</code></pre><p>In the example above the <a href="../../../doc/system/code_loading.html#on_load"><em><code class="inline">on_load</code></em></a>
│ │ │  directive is used get function <code class="inline">init</code> called automatically when the module is
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_prim_loader.html
│ │ │ @@ -398,15 +398,15 @@
│ │ │                          when Filename :: <a href="erlang.html#t:string/0">string</a>(), FileInfo :: <a href="../../../lib/kernel-10.2.7.2/doc/html/file.html#t:file_info/0">file:file_info</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Retrieves information about a file.</p><p>Returns <code class="inline">{ok, FileInfo}</code> if successful, otherwise <code class="inline">error</code>. <code class="inline">FileInfo</code> is a
│ │ │  record <a href="../../../lib/kernel-10.2.7.2/doc/html/file.html#t:file_info/0"><code class="inline">file_info</code></a>, defined in the Kernel include file
│ │ │   <code class="inline">file.hrl</code>. Include the following directive in the module from which the
│ │ │ -function is called:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="9584942436-1">(</span><span class="s">&quot;kernel/include/file.hrl&quot;</span><span class="p" data-group-id="9584942436-1">)</span><span class="p">.</span></code></pre><p>For more information about the record see <a href="../../../lib/kernel-10.2.7.2/doc/html/file.html#read_file_info/2"><code class="inline">file:read_file_info/2</code></a>.</p><p><code class="inline">Filename</code> can also be a file in an archive, for example,
│ │ │ +function is called:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">include_lib</span><span class="p" data-group-id="4760571398-1">(</span><span class="s">&quot;kernel/include/file.hrl&quot;</span><span class="p" data-group-id="4760571398-1">)</span><span class="p">.</span></code></pre><p>For more information about the record see <a href="../../../lib/kernel-10.2.7.2/doc/html/file.html#read_file_info/2"><code class="inline">file:read_file_info/2</code></a>.</p><p><code class="inline">Filename</code> can also be a file in an archive, for example,
│ │ │  <code class="inline">$OTPROOT/lib/mnesia-4.4.7.ez/mnesia-4.4.7/ebin/mnesia</code>. For information
│ │ │  about archive files, see <a href="../../../lib/kernel-10.2.7.2/doc/html/code.html"><code class="inline">code</code></a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="read_link_info/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erl_tracer.html
│ │ │ @@ -145,44 +145,44 @@
│ │ │    <span class="text">Erl Tracer Module Example</span>
│ │ │  </h2>
│ │ │  <p>In this example, a tracer module with a NIF back end sends a message for each
│ │ │  <code class="inline">send</code> trace tag containing only the sender and receiver. Using this tracer
│ │ │  module, a much more lightweight message tracer is used, which only records who
│ │ │  sent messages to who.</p><p>The following is an example session using it on Linux:</p><pre><code class="makeup erlang" translate="no"><span class="sc">$ </span><span class="ss">gcc</span><span class="w"> </span><span class="o">-</span><span class="n">I</span><span class="w"> </span><span class="ss">erts</span><span class="o">-</span><span class="mf">8.0</span><span class="o">/</span><span class="ss">include</span><span class="o">/</span><span class="w"> </span><span class="o">-</span><span class="ss">fPIC</span><span class="w"> </span><span class="o">-</span><span class="ss">shared</span><span class="w"> </span><span class="o">-</span><span class="ss">o</span><span class="w"> </span><span class="ss">erl_msg_tracer</span><span class="p">.</span><span class="ss">so</span><span class="w"> </span><span class="ss">erl_msg_tracer</span><span class="p">.</span><span class="ss">c</span><span class="w">
│ │ │  </span><span class="sc">$ </span><span class="ss">erl</span><span class="w">
│ │ │ -</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">19</span><span class="w"> </span><span class="p" data-group-id="5048982441-1">[</span><span class="n">DEVELOPMENT</span><span class="p" data-group-id="5048982441-1">]</span><span class="w"> </span><span class="p" data-group-id="5048982441-2">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">8.0</span><span class="p" data-group-id="5048982441-2">]</span><span class="w"> </span><span class="p" data-group-id="5048982441-3">[</span><span class="ss">source</span><span class="o">-</span><span class="ss">ed2b56b</span><span class="p" data-group-id="5048982441-3">]</span><span class="w"> </span><span class="p" data-group-id="5048982441-4">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="5048982441-4">]</span><span class="w"> </span><span class="p" data-group-id="5048982441-5">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="5048982441-5">]</span><span class="w"> </span><span class="p" data-group-id="5048982441-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="5048982441-6">]</span><span class="w"> </span><span class="p" data-group-id="5048982441-7">[</span><span class="ss">hipe</span><span class="p" data-group-id="5048982441-7">]</span><span class="w"> </span><span class="p" data-group-id="5048982441-8">[</span><span class="ss">kernel</span><span class="o">-</span><span class="nc">poll</span><span class="p">:</span><span class="ss">false</span><span class="p" data-group-id="5048982441-8">]</span><span class="w">
│ │ │ +</span><span class="n">Erlang</span><span class="o">/</span><span class="n">OTP</span><span class="w"> </span><span class="mi">19</span><span class="w"> </span><span class="p" data-group-id="3574915603-1">[</span><span class="n">DEVELOPMENT</span><span class="p" data-group-id="3574915603-1">]</span><span class="w"> </span><span class="p" data-group-id="3574915603-2">[</span><span class="ss">erts</span><span class="o">-</span><span class="mf">8.0</span><span class="p" data-group-id="3574915603-2">]</span><span class="w"> </span><span class="p" data-group-id="3574915603-3">[</span><span class="ss">source</span><span class="o">-</span><span class="ss">ed2b56b</span><span class="p" data-group-id="3574915603-3">]</span><span class="w"> </span><span class="p" data-group-id="3574915603-4">[</span><span class="mi">64</span><span class="o">-</span><span class="ss">bit</span><span class="p" data-group-id="3574915603-4">]</span><span class="w"> </span><span class="p" data-group-id="3574915603-5">[</span><span class="nc">smp</span><span class="p">:</span><span class="mi">8</span><span class="p">:</span><span class="mi">8</span><span class="p" data-group-id="3574915603-5">]</span><span class="w"> </span><span class="p" data-group-id="3574915603-6">[</span><span class="ss">async</span><span class="o">-</span><span class="nc">threads</span><span class="p">:</span><span class="mi">10</span><span class="p" data-group-id="3574915603-6">]</span><span class="w"> </span><span class="p" data-group-id="3574915603-7">[</span><span class="ss">hipe</span><span class="p" data-group-id="3574915603-7">]</span><span class="w"> </span><span class="p" data-group-id="3574915603-8">[</span><span class="ss">kernel</span><span class="o">-</span><span class="nc">poll</span><span class="p">:</span><span class="ss">false</span><span class="p" data-group-id="3574915603-8">]</span><span class="w">
│ │ │  
│ │ │ -</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V8</span><span class="p">.</span><span class="mi">0</span><span class="w">  </span><span class="p" data-group-id="5048982441-9">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="5048982441-9">)</span><span class="gp unselectable">
│ │ │ -1&gt; </span><span class="nf">c</span><span class="p" data-group-id="5048982441-10">(</span><span class="ss">erl_msg_tracer</span><span class="p" data-group-id="5048982441-10">)</span><span class="p">,</span><span class="w"> </span><span class="nc">erl_msg_tracer</span><span class="p">:</span><span class="nf">load</span><span class="p" data-group-id="5048982441-11">(</span><span class="p" data-group-id="5048982441-11">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="n">Eshell</span><span class="w"> </span><span class="n">V8</span><span class="p">.</span><span class="mi">0</span><span class="w">  </span><span class="p" data-group-id="3574915603-9">(</span><span class="ss">abort</span><span class="w"> </span><span class="ss">with</span><span class="w"> </span><span class="err">^</span><span class="n">G</span><span class="p" data-group-id="3574915603-9">)</span><span class="gp unselectable">
│ │ │ +1&gt; </span><span class="nf">c</span><span class="p" data-group-id="3574915603-10">(</span><span class="ss">erl_msg_tracer</span><span class="p" data-group-id="3574915603-10">)</span><span class="p">,</span><span class="w"> </span><span class="nc">erl_msg_tracer</span><span class="p">:</span><span class="nf">load</span><span class="p" data-group-id="3574915603-11">(</span><span class="p" data-group-id="3574915603-11">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="n">Tracer</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="5048982441-12">(</span><span class="k">fun</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="5048982441-13">(</span><span class="p" data-group-id="5048982441-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="5048982441-14">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="5048982441-15">[</span><span class="n">M</span><span class="p" data-group-id="5048982441-15">]</span><span class="p" data-group-id="5048982441-14">)</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="5048982441-16">(</span><span class="p" data-group-id="5048982441-16">)</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="5048982441-12">)</span><span class="p">.</span><span class="w">
│ │ │ +2&gt; </span><span class="n">Tracer</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">spawn</span><span class="p" data-group-id="3574915603-12">(</span><span class="k">fun</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="3574915603-13">(</span><span class="p" data-group-id="3574915603-13">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">receive</span><span class="w"> </span><span class="n">M</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3574915603-14">(</span><span class="s">&quot;</span><span class="si">~p</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="p" data-group-id="3574915603-15">[</span><span class="n">M</span><span class="p" data-group-id="3574915603-15">]</span><span class="p" data-group-id="3574915603-14">)</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="p" data-group-id="3574915603-16">(</span><span class="p" data-group-id="3574915603-16">)</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="3574915603-12">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.37</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="gp unselectable">
│ │ │ -3&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="5048982441-17">(</span><span class="ss">new</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5048982441-18">[</span><span class="nb">send</span><span class="p">,</span><span class="p" data-group-id="5048982441-19">{</span><span class="ss">tracer</span><span class="p">,</span><span class="w"> </span><span class="ss">erl_msg_tracer</span><span class="p">,</span><span class="w"> </span><span class="n">Tracer</span><span class="p" data-group-id="5048982441-19">}</span><span class="p" data-group-id="5048982441-18">]</span><span class="p" data-group-id="5048982441-17">)</span><span class="p">.</span><span class="w">
│ │ │ +3&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">trace</span><span class="p" data-group-id="3574915603-17">(</span><span class="ss">new</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3574915603-18">[</span><span class="nb">send</span><span class="p">,</span><span class="p" data-group-id="3574915603-19">{</span><span class="ss">tracer</span><span class="p">,</span><span class="w"> </span><span class="ss">erl_msg_tracer</span><span class="p">,</span><span class="w"> </span><span class="n">Tracer</span><span class="p" data-group-id="3574915603-19">}</span><span class="p" data-group-id="3574915603-18">]</span><span class="p" data-group-id="3574915603-17">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">0</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-20">{</span><span class="nb">trace</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.39</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.27</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-20">}</span><span class="gp unselectable">
│ │ │ -4&gt; </span><span class="p" data-group-id="5048982441-21">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="5048982441-21">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="5048982441-22">(</span><span class="s">&quot;/tmp/tmp.data&quot;</span><span class="p">,</span><span class="p" data-group-id="5048982441-23">[</span><span class="ss">write</span><span class="p" data-group-id="5048982441-23">]</span><span class="p" data-group-id="5048982441-22">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-24">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.486</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.40</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-24">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-25">{</span><span class="nb">trace</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.40</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.21</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-25">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-26">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.487</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-26">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-27">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.488</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-27">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-28">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.489</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-28">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-29">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.490</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-29">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-30">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.40</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-30">}</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5048982441-31">{</span><span class="nb">trace</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.41</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.27</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="5048982441-31">}</span><span class="w">
│ │ │ -</span><span class="mi">5</span><span class="o">&gt;</span></code></pre><p><code class="inline">erl_msg_tracer.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="8021172340-1">(</span><span class="ss">erl_msg_tracer</span><span class="p" data-group-id="8021172340-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-20">{</span><span class="nb">trace</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.39</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.27</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-20">}</span><span class="gp unselectable">
│ │ │ +4&gt; </span><span class="p" data-group-id="3574915603-21">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">D</span><span class="p" data-group-id="3574915603-21">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">file</span><span class="p">:</span><span class="nf">open</span><span class="p" data-group-id="3574915603-22">(</span><span class="s">&quot;/tmp/tmp.data&quot;</span><span class="p">,</span><span class="p" data-group-id="3574915603-23">[</span><span class="ss">write</span><span class="p" data-group-id="3574915603-23">]</span><span class="p" data-group-id="3574915603-22">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-24">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.486</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.40</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-24">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-25">{</span><span class="nb">trace</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.40</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.21</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-25">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-26">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.487</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-26">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-27">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.488</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-27">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-28">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.489</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-28">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-29">{</span><span class="nb">trace</span><span class="p">,</span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.490</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-29">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-30">{</span><span class="ss">ok</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.40</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-30">}</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3574915603-31">{</span><span class="nb">trace</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.41</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.27</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="3574915603-31">}</span><span class="w">
│ │ │ +</span><span class="mi">5</span><span class="o">&gt;</span></code></pre><p><code class="inline">erl_msg_tracer.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="5686920302-1">(</span><span class="ss">erl_msg_tracer</span><span class="p" data-group-id="5686920302-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="8021172340-2">(</span><span class="p" data-group-id="8021172340-3">[</span><span class="ss">enabled</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="nb">trace</span><span class="p">/</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="ss">load</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="8021172340-3">]</span><span class="p" data-group-id="8021172340-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="5686920302-2">(</span><span class="p" data-group-id="5686920302-3">[</span><span class="ss">enabled</span><span class="p">/</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="nb">trace</span><span class="p">/</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="ss">load</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="5686920302-3">]</span><span class="p" data-group-id="5686920302-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">load</span><span class="p" data-group-id="8021172340-4">(</span><span class="p" data-group-id="8021172340-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="8021172340-5">(</span><span class="s">&quot;erl_msg_tracer&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8021172340-6">[</span><span class="p" data-group-id="8021172340-6">]</span><span class="p" data-group-id="8021172340-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">load</span><span class="p" data-group-id="5686920302-4">(</span><span class="p" data-group-id="5686920302-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">load_nif</span><span class="p" data-group-id="5686920302-5">(</span><span class="s">&quot;erl_msg_tracer&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5686920302-6">[</span><span class="p" data-group-id="5686920302-6">]</span><span class="p" data-group-id="5686920302-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">enabled</span><span class="p" data-group-id="8021172340-7">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="8021172340-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">enabled</span><span class="p" data-group-id="5686920302-7">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="5686920302-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">error</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">trace</span><span class="p" data-group-id="8021172340-8">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="8021172340-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">trace</span><span class="p" data-group-id="5686920302-8">(</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="5686920302-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="ss">error</span><span class="p">.</span></code></pre><p><code class="inline">erl_msg_tracer.c</code>:</p><pre><code class="c">#include &lt;erl_nif.h&gt;
│ │ │  
│ │ │  /* NIF interface declarations */
│ │ │  static int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info);
│ │ │  static int upgrade(ErlNifEnv* env, void** priv_data, void** old_priv_data, ERL_NIF_TERM load_info);
│ │ │  static void unload(ErlNifEnv* env, void* priv_data);
│ │ ├── ./usr/share/doc/erlang-doc/html/erts-15.2.7.3/doc/html/erlang.html
│ │ │ @@ -6846,16 +6846,16 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> adler32(OldAdler, Data) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when OldAdler :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(), Data :: <a href="#t:iodata/0">iodata</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Continues computing the adler32 checksum by combining the previous checksum,
│ │ │ -<code class="inline">OldAdler</code>, with the checksum of <code class="inline">Data</code>.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="0187536269-1">(</span><span class="n">Data1</span><span class="p" data-group-id="0187536269-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="0187536269-2">(</span><span class="n">X</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="0187536269-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Y</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="2953424807-1">(</span><span class="p" data-group-id="2953424807-2">[</span><span class="n">Data1</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="2953424807-2">]</span><span class="p" data-group-id="2953424807-1">)</span><span class="p">.</span></code></pre>
│ │ │ +<code class="inline">OldAdler</code>, with the checksum of <code class="inline">Data</code>.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="3109331653-1">(</span><span class="n">Data1</span><span class="p" data-group-id="3109331653-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="3109331653-2">(</span><span class="n">X</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="3109331653-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Y</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="5735987424-1">(</span><span class="p" data-group-id="5735987424-2">[</span><span class="n">Data1</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="5735987424-2">]</span><span class="p" data-group-id="5735987424-1">)</span><span class="p">.</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="adler32_combine/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#adler32_combine/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -6878,18 +6878,18 @@
│ │ │                               FirstAdler :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(),
│ │ │                               SecondAdler :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(),
│ │ │                               SecondSize :: <a href="#t:non_neg_integer/0">non_neg_integer</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Combines two previously computed adler32 checksums.</p><p>This computation requires the size of the data object for the second checksum
│ │ │ -to be known.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="1242429559-1">(</span><span class="n">Data1</span><span class="p" data-group-id="1242429559-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="1242429559-2">(</span><span class="n">Y</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="1242429559-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Z</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="3426859125-1">(</span><span class="n">Data1</span><span class="p" data-group-id="3426859125-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="3426859125-2">(</span><span class="n">Data2</span><span class="p" data-group-id="3426859125-2">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32_combine</span><span class="p" data-group-id="3426859125-3">(</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="nf">iolist_size</span><span class="p" data-group-id="3426859125-4">(</span><span class="n">Data2</span><span class="p" data-group-id="3426859125-4">)</span><span class="p" data-group-id="3426859125-3">)</span><span class="p">.</span></code></pre>
│ │ │ +to be known.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="3421285454-1">(</span><span class="n">Data1</span><span class="p" data-group-id="3421285454-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="3421285454-2">(</span><span class="n">Y</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="3421285454-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Z</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="8337129083-1">(</span><span class="n">Data1</span><span class="p" data-group-id="8337129083-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32</span><span class="p" data-group-id="8337129083-2">(</span><span class="n">Data2</span><span class="p" data-group-id="8337129083-2">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">adler32_combine</span><span class="p" data-group-id="8337129083-3">(</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="nf">iolist_size</span><span class="p" data-group-id="8337129083-4">(</span><span class="n">Data2</span><span class="p" data-group-id="8337129083-4">)</span><span class="p" data-group-id="8337129083-3">)</span><span class="p">.</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="crc32/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#crc32/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -6934,16 +6934,16 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> crc32(OldCrc, Data) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when OldCrc :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(), Data :: <a href="#t:iodata/0">iodata</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Continues computing the crc32 checksum by combining the previous checksum,
│ │ │ -<code class="inline">OldCrc</code>, with the checksum of <code class="inline">Data</code>.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="5592566894-1">(</span><span class="n">Data1</span><span class="p" data-group-id="5592566894-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="5592566894-2">(</span><span class="n">X</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="5592566894-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Y</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="8569182757-1">(</span><span class="p" data-group-id="8569182757-2">[</span><span class="n">Data1</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="8569182757-2">]</span><span class="p" data-group-id="8569182757-1">)</span><span class="p">.</span></code></pre>
│ │ │ +<code class="inline">OldCrc</code>, with the checksum of <code class="inline">Data</code>.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="6324055835-1">(</span><span class="n">Data1</span><span class="p" data-group-id="6324055835-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="6324055835-2">(</span><span class="n">X</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="6324055835-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Y</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="7187522202-1">(</span><span class="p" data-group-id="7187522202-2">[</span><span class="n">Data1</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="7187522202-2">]</span><span class="p" data-group-id="7187522202-1">)</span><span class="p">.</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="crc32_combine/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#crc32_combine/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -6966,18 +6966,18 @@
│ │ │                             FirstCrc :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(),
│ │ │                             SecondCrc :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(),
│ │ │                             SecondSize :: <a href="#t:non_neg_integer/0">non_neg_integer</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Combines two previously computed crc32 checksums.</p><p>This computation requires the size of the data object for the second checksum
│ │ │ -to be known.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="8368078205-1">(</span><span class="n">Data1</span><span class="p" data-group-id="8368078205-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="8368078205-2">(</span><span class="n">Y</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="8368078205-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Z</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="8132737276-1">(</span><span class="n">Data1</span><span class="p" data-group-id="8132737276-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="8132737276-2">(</span><span class="n">Data2</span><span class="p" data-group-id="8132737276-2">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32_combine</span><span class="p" data-group-id="8132737276-3">(</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="nf">iolist_size</span><span class="p" data-group-id="8132737276-4">(</span><span class="n">Data2</span><span class="p" data-group-id="8132737276-4">)</span><span class="p" data-group-id="8132737276-3">)</span><span class="p">.</span></code></pre>
│ │ │ +to be known.</p><p>The following code:</p><pre><code class="makeup erlang" translate="no"><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="7543768911-1">(</span><span class="n">Data1</span><span class="p" data-group-id="7543768911-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="7543768911-2">(</span><span class="n">Y</span><span class="p">,</span><span class="n">Data2</span><span class="p" data-group-id="7543768911-2">)</span><span class="p">.</span></code></pre><p>assigns the same value to <code class="inline">Z</code> as this:</p><pre><code class="makeup erlang" translate="no"><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="3232706974-1">(</span><span class="n">Data1</span><span class="p" data-group-id="3232706974-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32</span><span class="p" data-group-id="3232706974-2">(</span><span class="n">Data2</span><span class="p" data-group-id="3232706974-2">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">crc32_combine</span><span class="p" data-group-id="3232706974-3">(</span><span class="n">X</span><span class="p">,</span><span class="n">Y</span><span class="p">,</span><span class="nf">iolist_size</span><span class="p" data-group-id="3232706974-4">(</span><span class="n">Data2</span><span class="p" data-group-id="3232706974-4">)</span><span class="p" data-group-id="3232706974-3">)</span><span class="p">.</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="md5/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#md5/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8129,19 +8129,19 @@
│ │ │  the <code class="inline">Info</code> map in the returned result will contain the key <code class="inline">node_type</code>
│ │ │  associated with the value <code class="inline">NodeTypeInfo</code>. Currently the following node types
│ │ │  exist:</p><ul><li><p><strong><code class="inline">visible</code></strong> - The node is connected to the node of the calling process
│ │ │  through an ordinary visible connection. That is, the node name would appear
│ │ │  in the result returned by <a href="#nodes/0"><code class="inline">nodes/0</code></a>.</p></li><li><p><strong><code class="inline">hidden</code></strong> - The node is connected to the node of the calling process
│ │ │  through a hidden connection. That is, the node name would <em>not</em> appear in
│ │ │  the result returned by <a href="#nodes/0"><code class="inline">nodes/0</code></a>.</p></li><li><p><strong><code class="inline">this</code></strong> - This is the node of the calling process.</p></li><li><p><strong><code class="inline">known</code></strong> - The node is not connected but known to the node of the calling
│ │ │ -process.</p></li></ul></li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(a@localhost)1&gt; </span><span class="nf">nodes</span><span class="p" data-group-id="0435291448-1">(</span><span class="p" data-group-id="0435291448-2">[</span><span class="ss">this</span><span class="p">,</span><span class="w"> </span><span class="ss">connected</span><span class="p" data-group-id="0435291448-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0435291448-3">#{</span><span class="ss">connection_id</span><span class="p">=&gt;</span><span class="ss">true</span><span class="p">,</span><span class="w"> </span><span class="ss">node_type</span><span class="p">=&gt;</span><span class="ss">true</span><span class="p" data-group-id="0435291448-3">}</span><span class="p" data-group-id="0435291448-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0435291448-4">[</span><span class="p" data-group-id="0435291448-5">{</span><span class="ss">c@localhost</span><span class="p">,</span><span class="p" data-group-id="0435291448-6">#{</span><span class="ss">connection_id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">13892108</span><span class="p">,</span><span class="ss">node_type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">hidden</span><span class="p" data-group-id="0435291448-6">}</span><span class="p" data-group-id="0435291448-5">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0435291448-7">{</span><span class="ss">b@localhost</span><span class="p">,</span><span class="p" data-group-id="0435291448-8">#{</span><span class="ss">connection_id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3067553</span><span class="p">,</span><span class="ss">node_type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">visible</span><span class="p" data-group-id="0435291448-8">}</span><span class="p" data-group-id="0435291448-7">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="0435291448-9">{</span><span class="ss">a@localhost</span><span class="p">,</span><span class="p" data-group-id="0435291448-10">#{</span><span class="ss">connection_id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">undefined</span><span class="p">,</span><span class="ss">node_type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">this</span><span class="p" data-group-id="0435291448-10">}</span><span class="p" data-group-id="0435291448-9">}</span><span class="p" data-group-id="0435291448-4">]</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0435291448-11">(</span><span class="ss">a@localhost</span><span class="p" data-group-id="0435291448-11">)</span><span class="mi">2</span><span class="o">&gt;</span></code></pre>
│ │ │ +process.</p></li></ul></li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">(a@localhost)1&gt; </span><span class="nf">nodes</span><span class="p" data-group-id="4420000992-1">(</span><span class="p" data-group-id="4420000992-2">[</span><span class="ss">this</span><span class="p">,</span><span class="w"> </span><span class="ss">connected</span><span class="p" data-group-id="4420000992-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4420000992-3">#{</span><span class="ss">connection_id</span><span class="p">=&gt;</span><span class="ss">true</span><span class="p">,</span><span class="w"> </span><span class="ss">node_type</span><span class="p">=&gt;</span><span class="ss">true</span><span class="p" data-group-id="4420000992-3">}</span><span class="p" data-group-id="4420000992-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4420000992-4">[</span><span class="p" data-group-id="4420000992-5">{</span><span class="ss">c@localhost</span><span class="p">,</span><span class="p" data-group-id="4420000992-6">#{</span><span class="ss">connection_id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">13892108</span><span class="p">,</span><span class="ss">node_type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">hidden</span><span class="p" data-group-id="4420000992-6">}</span><span class="p" data-group-id="4420000992-5">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="4420000992-7">{</span><span class="ss">b@localhost</span><span class="p">,</span><span class="p" data-group-id="4420000992-8">#{</span><span class="ss">connection_id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">3067553</span><span class="p">,</span><span class="ss">node_type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">visible</span><span class="p" data-group-id="4420000992-8">}</span><span class="p" data-group-id="4420000992-7">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="4420000992-9">{</span><span class="ss">a@localhost</span><span class="p">,</span><span class="p" data-group-id="4420000992-10">#{</span><span class="ss">connection_id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">undefined</span><span class="p">,</span><span class="ss">node_type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">this</span><span class="p" data-group-id="4420000992-10">}</span><span class="p" data-group-id="4420000992-9">}</span><span class="p" data-group-id="4420000992-4">]</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4420000992-11">(</span><span class="ss">a@localhost</span><span class="p" data-group-id="4420000992-11">)</span><span class="mi">2</span><span class="o">&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="set_cookie/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#set_cookie/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8237,17 +8237,17 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> abs(Float) -> <a href="#t:float/0">float</a>() when Float :: <a href="#t:float/0">float</a>();
│ │ │           (Int) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Int :: <a href="#t:integer/0">integer</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns an integer or float that is the arithmetical absolute value of <code class="inline">Float</code>
│ │ │ -or <code class="inline">Int</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">abs</span><span class="p" data-group-id="0248678142-1">(</span><span class="o">-</span><span class="mf">3.33</span><span class="p" data-group-id="0248678142-1">)</span><span class="p">.</span><span class="w">
│ │ │ +or <code class="inline">Int</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">abs</span><span class="p" data-group-id="2380086192-1">(</span><span class="o">-</span><span class="mf">3.33</span><span class="p" data-group-id="2380086192-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">3.33</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">abs</span><span class="p" data-group-id="0248678142-2">(</span><span class="o">-</span><span class="mi">3</span><span class="p" data-group-id="0248678142-2">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">abs</span><span class="p" data-group-id="2380086192-2">(</span><span class="o">-</span><span class="mi">3</span><span class="p" data-group-id="2380086192-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="append_element/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#append_element/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -8269,16 +8269,16 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> append_element(Tuple1, Term) -> Tuple2 when Tuple1 :: <a href="#t:tuple/0">tuple</a>(), Tuple2 :: <a href="#t:tuple/0">tuple</a>(), Term :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a new tuple that has one element more than <code class="inline">Tuple1</code>, and contains the
│ │ │  elements in <code class="inline">Tuple1</code> followed by <code class="inline">Term</code> as the last element.</p><p>Semantically equivalent to
│ │ │  <a href="#list_to_tuple/1"><code class="inline">list_to_tuple(tuple_to_list(Tuple1) ++ [Term])</code></a>, but much
│ │ │ -faster.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">append_element</span><span class="p" data-group-id="5780832225-1">(</span><span class="p" data-group-id="5780832225-2">{</span><span class="ss">one</span><span class="p">,</span><span class="w"> </span><span class="ss">two</span><span class="p" data-group-id="5780832225-2">}</span><span class="p">,</span><span class="w"> </span><span class="ss">three</span><span class="p" data-group-id="5780832225-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5780832225-3">{</span><span class="ss">one</span><span class="p">,</span><span class="ss">two</span><span class="p">,</span><span class="ss">three</span><span class="p" data-group-id="5780832225-3">}</span></code></pre>
│ │ │ +faster.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">append_element</span><span class="p" data-group-id="1765945688-1">(</span><span class="p" data-group-id="1765945688-2">{</span><span class="ss">one</span><span class="p">,</span><span class="w"> </span><span class="ss">two</span><span class="p" data-group-id="1765945688-2">}</span><span class="p">,</span><span class="w"> </span><span class="ss">three</span><span class="p" data-group-id="1765945688-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1765945688-3">{</span><span class="ss">one</span><span class="p">,</span><span class="ss">two</span><span class="p">,</span><span class="ss">three</span><span class="p" data-group-id="1765945688-3">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="atom_to_binary/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#atom_to_binary/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8333,16 +8333,16 @@
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a binary corresponding to the text representation of <code class="inline">Atom</code>.</p><p>If <code class="inline">Encoding</code> is <code class="inline">latin1</code>, one byte exists for each character in the text
│ │ │  representation. If <code class="inline">Encoding</code> is <code class="inline">utf8</code> or <code class="inline">unicode</code>, the characters are encoded
│ │ │  using UTF-8 where characters may require multiple bytes.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>As from Erlang/OTP 20, atoms can contain any Unicode character and
│ │ │  <a href="#atom_to_binary/2"><code class="inline">atom_to_binary(Atom, latin1)</code></a> may fail if the text
│ │ │ -representation for <code class="inline">Atom</code> contains a Unicode character &gt; 255.</p></section><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">atom_to_binary</span><span class="p" data-group-id="7396496056-1">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p">,</span><span class="w"> </span><span class="ss">latin1</span><span class="p" data-group-id="7396496056-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7396496056-2">&lt;&lt;</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="7396496056-2">&gt;&gt;</span></code></pre>
│ │ │ +representation for <code class="inline">Atom</code> contains a Unicode character &gt; 255.</p></section><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">atom_to_binary</span><span class="p" data-group-id="1813799299-1">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p">,</span><span class="w"> </span><span class="ss">latin1</span><span class="p" data-group-id="1813799299-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1813799299-2">&lt;&lt;</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="1813799299-2">&gt;&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="atom_to_list/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#atom_to_list/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8363,17 +8363,17 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> atom_to_list(Atom) -> <a href="#t:string/0">string</a>() when Atom :: <a href="#t:atom/0">atom</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a list of unicode code points corresponding to the text representation
│ │ │ -of <code class="inline">Atom</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="8827219753-1">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="8827219753-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="s">&quot;Erlang&quot;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="9459203553-1">(</span><span class="ss">&#39;你好&#39;</span><span class="p" data-group-id="9459203553-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9459203553-2">[</span><span class="mi">20320</span><span class="p">,</span><span class="mi">22909</span><span class="p" data-group-id="9459203553-2">]</span></code></pre><p>See <a href="../../../lib/stdlib-6.2.2.2/doc/html/unicode.html"><code class="inline">unicode</code></a> for how to convert the resulting list to different formats.</p>
│ │ │ +of <code class="inline">Atom</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="0040776293-1">(</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="0040776293-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="s">&quot;Erlang&quot;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">atom_to_list</span><span class="p" data-group-id="2204426379-1">(</span><span class="ss">&#39;你好&#39;</span><span class="p" data-group-id="2204426379-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2204426379-2">[</span><span class="mi">20320</span><span class="p">,</span><span class="mi">22909</span><span class="p" data-group-id="2204426379-2">]</span></code></pre><p>See <a href="../../../lib/stdlib-6.2.2.2/doc/html/unicode.html"><code class="inline">unicode</code></a> for how to convert the resulting list to different formats.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="binary_part/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#binary_part/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8400,19 +8400,19 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> binary_part(Subject, PosLen) -> <a href="#t:binary/0">binary</a>()
│ │ │                       when
│ │ │                           Subject :: <a href="#t:binary/0">binary</a>(),
│ │ │                           PosLen :: {Start :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(), Length :: <a href="#t:integer/0">integer</a>()}.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Extracts the part of the binary described by <code class="inline">PosLen</code>.</p><p>Negative length can be used to extract bytes at the end of a binary. </p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7059486549-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="7059486549-1">&gt;&gt;</span><span class="p">.</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">binary_part</span><span class="p" data-group-id="7059486549-2">(</span><span class="n">Bin</span><span class="p">,</span><span class="p" data-group-id="7059486549-3">{</span><span class="nf">byte_size</span><span class="p" data-group-id="7059486549-4">(</span><span class="n">Bin</span><span class="p" data-group-id="7059486549-4">)</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">5</span><span class="p" data-group-id="7059486549-3">}</span><span class="p" data-group-id="7059486549-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7059486549-5">&lt;&lt;</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="7059486549-5">&gt;&gt;</span></code></pre><p>Failure: <code class="inline">badarg</code> if <code class="inline">PosLen</code> in any way references outside the binary.</p><p><code class="inline">Start</code> is zero-based, that is:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9161316956-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="9161316956-1">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -2&gt; </span><span class="nf">binary_part</span><span class="p" data-group-id="9161316956-2">(</span><span class="n">Bin</span><span class="p">,</span><span class="p" data-group-id="9161316956-3">{</span><span class="mi">0</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9161316956-3">}</span><span class="p" data-group-id="9161316956-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9161316956-4">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="9161316956-4">&gt;&gt;</span></code></pre><p>For details about the <code class="inline">PosLen</code> semantics, see <a href="../../../lib/stdlib-6.2.2.2/doc/html/binary.html"><code class="inline">binary</code></a>.</p>
│ │ │ +<p>Extracts the part of the binary described by <code class="inline">PosLen</code>.</p><p>Negative length can be used to extract bytes at the end of a binary. </p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3512452101-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="3512452101-1">&gt;&gt;</span><span class="p">.</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nf">binary_part</span><span class="p" data-group-id="3512452101-2">(</span><span class="n">Bin</span><span class="p">,</span><span class="p" data-group-id="3512452101-3">{</span><span class="nf">byte_size</span><span class="p" data-group-id="3512452101-4">(</span><span class="n">Bin</span><span class="p" data-group-id="3512452101-4">)</span><span class="p">,</span><span class="w"> </span><span class="o">-</span><span class="mi">5</span><span class="p" data-group-id="3512452101-3">}</span><span class="p" data-group-id="3512452101-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3512452101-5">&lt;&lt;</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p">,</span><span class="mi">10</span><span class="p" data-group-id="3512452101-5">&gt;&gt;</span></code></pre><p>Failure: <code class="inline">badarg</code> if <code class="inline">PosLen</code> in any way references outside the binary.</p><p><code class="inline">Start</code> is zero-based, that is:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">1&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1721189001-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1721189001-1">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +2&gt; </span><span class="nf">binary_part</span><span class="p" data-group-id="1721189001-2">(</span><span class="n">Bin</span><span class="p">,</span><span class="p" data-group-id="1721189001-3">{</span><span class="mi">0</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1721189001-3">}</span><span class="p" data-group-id="1721189001-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1721189001-4">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1721189001-4">&gt;&gt;</span></code></pre><p>For details about the <code class="inline">PosLen</code> semantics, see <a href="../../../lib/stdlib-6.2.2.2/doc/html/binary.html"><code class="inline">binary</code></a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="binary_part/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#binary_part/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8505,16 +8505,16 @@
│ │ │  capable of decoding any Unicode character. Earlier versions would fail if the
│ │ │  binary contained Unicode characters &gt; 255.</p></section><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The number of characters that are permitted in an atom name is limited. The
│ │ │  default limits can be found in the
│ │ │  <a href="../../../doc/system/system_limits.html">Efficiency Guide (section System Limits)</a>.</p></section><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>There is configurable limit on how many atoms that can exist and atoms are not
│ │ │  garbage collected. Therefore, it is recommended to consider whether
│ │ │  <a href="#binary_to_existing_atom/2"><code class="inline">binary_to_existing_atom/2</code></a> is a better option
│ │ │  than <a href="#binary_to_atom/2"><code class="inline">binary_to_atom/2</code></a>. The default limits can be found
│ │ │ -in <a href="../../../doc/system/system_limits.html#atoms">Efficiency Guide (section System Limits)</a>.</p></section><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_atom</span><span class="p" data-group-id="4177795535-1">(</span><span class="p" data-group-id="4177795535-2">&lt;&lt;</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="4177795535-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="ss">latin1</span><span class="p" data-group-id="4177795535-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="ss">&#39;Erlang&#39;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_atom</span><span class="p" data-group-id="5846790812-1">(</span><span class="p" data-group-id="5846790812-2">&lt;&lt;</span><span class="mi">1024</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="5846790812-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="ss">utf8</span><span class="p" data-group-id="5846790812-1">)</span><span class="p">.</span><span class="w">
│ │ │ +in <a href="../../../doc/system/system_limits.html#atoms">Efficiency Guide (section System Limits)</a>.</p></section><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_atom</span><span class="p" data-group-id="2472218683-1">(</span><span class="p" data-group-id="2472218683-2">&lt;&lt;</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="2472218683-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="ss">latin1</span><span class="p" data-group-id="2472218683-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="ss">&#39;Erlang&#39;</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_atom</span><span class="p" data-group-id="1650923661-1">(</span><span class="p" data-group-id="1650923661-2">&lt;&lt;</span><span class="mi">1024</span><span class="o">/</span><span class="ss">utf8</span><span class="p" data-group-id="1650923661-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="ss">utf8</span><span class="p" data-group-id="1650923661-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">&#39;Ѐ&#39;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="binary_to_existing_atom/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#binary_to_existing_atom/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -8613,15 +8613,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> binary_to_float(Binary) -> <a href="#t:float/0">float</a>() when Binary :: <a href="#t:binary/0">binary</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the float whose text representation is <code class="inline">Binary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_float</span><span class="p" data-group-id="2789751220-1">(</span><span class="p" data-group-id="2789751220-2">&lt;&lt;</span><span class="s">&quot;2.2017764e+0&quot;</span><span class="p" data-group-id="2789751220-2">&gt;&gt;</span><span class="p" data-group-id="2789751220-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the float whose text representation is <code class="inline">Binary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_float</span><span class="p" data-group-id="6247514863-1">(</span><span class="p" data-group-id="6247514863-2">&lt;&lt;</span><span class="s">&quot;2.2017764e+0&quot;</span><span class="p" data-group-id="6247514863-2">&gt;&gt;</span><span class="p" data-group-id="6247514863-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">2.2017764</span></code></pre><p>The float string format is the same as the format for
│ │ │  <a href="../../../doc/system/data_types.html">Erlang float literals</a> except for that underscores
│ │ │  are not permitted.</p><p>Failure: <code class="inline">badarg</code> if <code class="inline">Binary</code> contains a bad representation of a float.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="binary_to_integer/1">
│ │ │  
│ │ │ @@ -8646,15 +8646,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> binary_to_integer(Binary) -> <a href="#t:integer/0">integer</a>() when Binary :: <a href="#t:binary/0">binary</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer whose text representation is <code class="inline">Binary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="1682443913-1">(</span><span class="p" data-group-id="1682443913-2">&lt;&lt;</span><span class="s">&quot;123&quot;</span><span class="p" data-group-id="1682443913-2">&gt;&gt;</span><span class="p" data-group-id="1682443913-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer whose text representation is <code class="inline">Binary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="1026570318-1">(</span><span class="p" data-group-id="1026570318-2">&lt;&lt;</span><span class="s">&quot;123&quot;</span><span class="p" data-group-id="1026570318-2">&gt;&gt;</span><span class="p" data-group-id="1026570318-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">123</span></code></pre><p><a href="#binary_to_integer/1"><code class="inline">binary_to_integer/1</code></a> accepts the same string formats
│ │ │  as <a href="#list_to_integer/1"><code class="inline">list_to_integer/1</code></a>.</p><p>Failure: <code class="inline">badarg</code> if <code class="inline">Binary</code> contains a bad representation of an integer.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="binary_to_integer/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -8678,15 +8678,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> binary_to_integer(Binary, Base) -> <a href="#t:integer/0">integer</a>() when Binary :: <a href="#t:binary/0">binary</a>(), Base :: 2..36.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer whose text representation in base <code class="inline">Base</code> is <code class="inline">Binary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="0783573911-1">(</span><span class="p" data-group-id="0783573911-2">&lt;&lt;</span><span class="s">&quot;3FF&quot;</span><span class="p" data-group-id="0783573911-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="0783573911-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer whose text representation in base <code class="inline">Base</code> is <code class="inline">Binary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_integer</span><span class="p" data-group-id="8085303919-1">(</span><span class="p" data-group-id="8085303919-2">&lt;&lt;</span><span class="s">&quot;3FF&quot;</span><span class="p" data-group-id="8085303919-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="8085303919-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">1023</span></code></pre><p><a href="#binary_to_integer/2"><code class="inline">binary_to_integer/2</code></a> accepts the same string formats
│ │ │  as <a href="#list_to_integer/2"><code class="inline">list_to_integer/2</code></a>.</p><p>Failure: <code class="inline">badarg</code> if <code class="inline">Binary</code> contains a bad representation of an integer.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="binary_to_list/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -8771,17 +8771,17 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> binary_to_term(Binary) -> <a href="#t:term/0">term</a>() when Binary :: <a href="#t:ext_binary/0">ext_binary</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns an Erlang term that is the result of decoding binary object <code class="inline">Binary</code>,
│ │ │  which must be encoded according to the
│ │ │ -<a href="erl_ext_dist.html">Erlang external term format</a>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="5267541959-1">(</span><span class="ss">hello</span><span class="p" data-group-id="5267541959-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="5267541959-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="5267541959-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="ss">hello</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="5267541959-3">(</span><span class="n">Bin</span><span class="p" data-group-id="5267541959-3">)</span><span class="p">.</span><span class="w">
│ │ │ +<a href="erl_ext_dist.html">Erlang external term format</a>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="0525736199-1">(</span><span class="ss">hello</span><span class="p" data-group-id="0525736199-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0525736199-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="0525736199-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="ss">hello</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="0525736199-3">(</span><span class="n">Bin</span><span class="p" data-group-id="0525736199-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span></code></pre><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p>When decoding binaries from untrusted sources, the untrusted source may submit
│ │ │  data in a way to create resources, such as atoms and remote references, that
│ │ │  cannot be garbage collected and lead to Denial of Service attack. In such
│ │ │  cases, consider using <a href="#binary_to_term/2"><code class="inline">binary_to_term/2</code></a> with the <code class="inline">safe</code>
│ │ │  option.</p></section><p>See also <a href="#term_to_binary/1"><code class="inline">term_to_binary/1</code></a> and <a href="#binary_to_term/2"><code class="inline">binary_to_term/2</code></a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │ @@ -8820,30 +8820,30 @@
│ │ │  <p>Equivalent to <a href="#binary_to_term/1"><code class="inline">binary_to_term(Binary)</code></a>, but can be configured to
│ │ │  fit special purposes.</p><p>The allowed options are:</p><ul><li><p><strong><code class="inline">safe</code></strong> - Use this option when receiving binaries from an untrusted source.</p><p>When enabled, it prevents decoding data that can be used to attack the Erlang
│ │ │  runtime. In the event of receiving unsafe data, decoding fails with a <code class="inline">badarg</code>
│ │ │  error.</p><p>This prevents creation of new atoms directly, creation of new atoms indirectly
│ │ │  (as they are embedded in certain structures, such as process identifiers,
│ │ │  refs, and funs), and creation of new external function references. None of
│ │ │  those resources are garbage collected, so unchecked creation of them can
│ │ │ -exhaust available memory.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="0425875780-1">(</span><span class="p" data-group-id="0425875780-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0425875780-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0425875780-3">[</span><span class="ss">safe</span><span class="p" data-group-id="0425875780-3">]</span><span class="p" data-group-id="0425875780-1">)</span><span class="p">.</span><span class="w">
│ │ │ +exhaust available memory.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="7399154349-1">(</span><span class="p" data-group-id="7399154349-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="7399154349-2">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7399154349-3">[</span><span class="ss">safe</span><span class="p" data-group-id="7399154349-3">]</span><span class="p" data-group-id="7399154349-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: bad argument</span><span class="gp unselectable">
│ │ │  &gt; </span><span class="ss">hello</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="0425875780-4">(</span><span class="p" data-group-id="0425875780-5">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="0425875780-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0425875780-6">[</span><span class="ss">safe</span><span class="p" data-group-id="0425875780-6">]</span><span class="p" data-group-id="0425875780-4">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">binary_to_term</span><span class="p" data-group-id="7399154349-4">(</span><span class="p" data-group-id="7399154349-5">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;hello&quot;</span><span class="p" data-group-id="7399154349-5">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7399154349-6">[</span><span class="ss">safe</span><span class="p" data-group-id="7399154349-6">]</span><span class="p" data-group-id="7399154349-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span></code></pre><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p>The <code class="inline">safe</code> option ensures the data is safely processed by the Erlang runtime
│ │ │  but it does not guarantee the data is safe to your application. You must
│ │ │  always validate data from untrusted sources. If the binary is stored or
│ │ │  transits through untrusted sources, you should also consider
│ │ │  cryptographically signing it.</p></section></li><li><p><strong><code class="inline">used</code></strong> - Changes the return value to <code class="inline">{Term, Used}</code> where <code class="inline">Used</code> is the
│ │ │ -number of bytes actually read from <code class="inline">Binary</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Input</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="9213888808-1">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="s">&quot;world&quot;</span><span class="p" data-group-id="9213888808-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9213888808-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p">,</span><span class="mi">119</span><span class="p">,</span><span class="mi">111</span><span class="p">,</span><span class="mi">114</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">100</span><span class="p" data-group-id="9213888808-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="p" data-group-id="9213888808-3">{</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="n">Used</span><span class="p" data-group-id="9213888808-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="9213888808-4">(</span><span class="n">Input</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9213888808-5">[</span><span class="ss">used</span><span class="p" data-group-id="9213888808-5">]</span><span class="p" data-group-id="9213888808-4">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9213888808-6">{</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="9213888808-6">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">split_binary</span><span class="p" data-group-id="9213888808-7">(</span><span class="n">Input</span><span class="p">,</span><span class="w"> </span><span class="n">Used</span><span class="p" data-group-id="9213888808-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9213888808-8">{</span><span class="p" data-group-id="9213888808-9">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="9213888808-9">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9213888808-10">&lt;&lt;</span><span class="s">&quot;world&quot;</span><span class="p" data-group-id="9213888808-10">&gt;&gt;</span><span class="p" data-group-id="9213888808-8">}</span></code></pre></li></ul><p>Failure: <code class="inline">badarg</code> if <code class="inline">safe</code> is specified and unsafe data is decoded.</p><p>See also <a href="#term_to_binary/1"><code class="inline">term_to_binary/1</code></a>, <a href="#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>, and <a href="#list_to_existing_atom/1"><code class="inline">list_to_existing_atom/1</code></a>.</p>
│ │ │ +number of bytes actually read from <code class="inline">Binary</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Input</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8576146749-1">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;hello&quot;</span><span class="p">,</span><span class="s">&quot;world&quot;</span><span class="p" data-group-id="8576146749-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8576146749-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p">,</span><span class="mi">119</span><span class="p">,</span><span class="mi">111</span><span class="p">,</span><span class="mi">114</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">100</span><span class="p" data-group-id="8576146749-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="p" data-group-id="8576146749-3">{</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="n">Used</span><span class="p" data-group-id="8576146749-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="8576146749-4">(</span><span class="n">Input</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8576146749-5">[</span><span class="ss">used</span><span class="p" data-group-id="8576146749-5">]</span><span class="p" data-group-id="8576146749-4">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8576146749-6">{</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="mi">9</span><span class="p" data-group-id="8576146749-6">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">split_binary</span><span class="p" data-group-id="8576146749-7">(</span><span class="n">Input</span><span class="p">,</span><span class="w"> </span><span class="n">Used</span><span class="p" data-group-id="8576146749-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8576146749-8">{</span><span class="p" data-group-id="8576146749-9">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="8576146749-9">&gt;&gt;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8576146749-10">&lt;&lt;</span><span class="s">&quot;world&quot;</span><span class="p" data-group-id="8576146749-10">&gt;&gt;</span><span class="p" data-group-id="8576146749-8">}</span></code></pre></li></ul><p>Failure: <code class="inline">badarg</code> if <code class="inline">safe</code> is specified and unsafe data is decoded.</p><p>See also <a href="#term_to_binary/1"><code class="inline">term_to_binary/1</code></a>, <a href="#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>, and <a href="#list_to_existing_atom/1"><code class="inline">list_to_existing_atom/1</code></a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="bit_size/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#bit_size/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8865,17 +8865,17 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> bit_size(Bitstring) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Bitstring :: <a href="#t:bitstring/0">bitstring</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer that is the size in bits of <code class="inline">Bitstring</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">bit_size</span><span class="p" data-group-id="3255867796-1">(</span><span class="p" data-group-id="3255867796-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="3255867796-2">&gt;&gt;</span><span class="p" data-group-id="3255867796-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer that is the size in bits of <code class="inline">Bitstring</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">bit_size</span><span class="p" data-group-id="7436350182-1">(</span><span class="p" data-group-id="7436350182-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="7436350182-2">&gt;&gt;</span><span class="p" data-group-id="7436350182-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">19</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">bit_size</span><span class="p" data-group-id="3255867796-3">(</span><span class="p" data-group-id="3255867796-4">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3255867796-4">&gt;&gt;</span><span class="p" data-group-id="3255867796-3">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">bit_size</span><span class="p" data-group-id="7436350182-3">(</span><span class="p" data-group-id="7436350182-4">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7436350182-4">&gt;&gt;</span><span class="p" data-group-id="7436350182-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">24</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="bitstring_to_list/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#bitstring_to_list/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -8897,17 +8897,17 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> bitstring_to_list(Bitstring) -> [<a href="#t:byte/0">byte</a>() | <a href="#t:bitstring/0">bitstring</a>()] when Bitstring :: <a href="#t:bitstring/0">bitstring</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a list of integers corresponding to the bytes of <code class="inline">Bitstring</code>.</p><p>If the number of bits in the binary is not divisible by 8, the last element of
│ │ │ -the list is a bitstring containing the remaining 1-7 bits.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">bitstring_to_list</span><span class="p" data-group-id="4131417301-1">(</span><span class="p" data-group-id="4131417301-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="4131417301-2">&gt;&gt;</span><span class="p" data-group-id="4131417301-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4131417301-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">177</span><span class="p" data-group-id="4131417301-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">bitstring_to_list</span><span class="p" data-group-id="9406744945-1">(</span><span class="p" data-group-id="9406744945-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="9406744945-2">&gt;&gt;</span><span class="p" data-group-id="9406744945-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9406744945-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">177</span><span class="p">,</span><span class="p" data-group-id="9406744945-4">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="9406744945-4">&gt;&gt;</span><span class="p" data-group-id="9406744945-3">]</span></code></pre>
│ │ │ +the list is a bitstring containing the remaining 1-7 bits.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">bitstring_to_list</span><span class="p" data-group-id="9028033149-1">(</span><span class="p" data-group-id="9028033149-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p" data-group-id="9028033149-2">&gt;&gt;</span><span class="p" data-group-id="9028033149-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9028033149-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">177</span><span class="p" data-group-id="9028033149-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">bitstring_to_list</span><span class="p" data-group-id="7308750127-1">(</span><span class="p" data-group-id="7308750127-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="7308750127-2">&gt;&gt;</span><span class="p" data-group-id="7308750127-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7308750127-3">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">177</span><span class="p">,</span><span class="p" data-group-id="7308750127-4">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="7308750127-4">&gt;&gt;</span><span class="p" data-group-id="7308750127-3">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="byte_size/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#byte_size/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -8931,17 +8931,17 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> byte_size(Bitstring) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Bitstring :: <a href="#t:bitstring/0">bitstring</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns an integer that is the number of bytes needed to contain <code class="inline">Bitstring</code>.
│ │ │  That is, if the number of bits in <code class="inline">Bitstring</code> is not divisible by 8, the
│ │ │ -resulting number of bytes is rounded <em>up</em>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="3900240263-1">(</span><span class="p" data-group-id="3900240263-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="3900240263-2">&gt;&gt;</span><span class="p" data-group-id="3900240263-1">)</span><span class="p">.</span><span class="w">
│ │ │ +resulting number of bytes is rounded <em>up</em>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="1244845760-1">(</span><span class="p" data-group-id="1244845760-2">&lt;&lt;</span><span class="mi">433</span><span class="p">:</span><span class="mi">16</span><span class="p">,</span><span class="mi">3</span><span class="p">:</span><span class="mi">3</span><span class="p" data-group-id="1244845760-2">&gt;&gt;</span><span class="p" data-group-id="1244845760-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="3900240263-3">(</span><span class="p" data-group-id="3900240263-4">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3900240263-4">&gt;&gt;</span><span class="p" data-group-id="3900240263-3">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="1244845760-3">(</span><span class="p" data-group-id="1244845760-4">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1244845760-4">&gt;&gt;</span><span class="p" data-group-id="1244845760-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="ceil/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#ceil/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -8966,15 +8966,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> ceil(Number) -> <a href="#t:integer/0">integer</a>() when Number :: <a href="#t:number/0">number</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the smallest integer not less than <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">ceil</span><span class="p" data-group-id="6292851988-1">(</span><span class="mf">5.5</span><span class="p" data-group-id="6292851988-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the smallest integer not less than <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">ceil</span><span class="p" data-group-id="8027755154-1">(</span><span class="mf">5.5</span><span class="p" data-group-id="8027755154-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">6</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="decode_packet/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#decode_packet/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -9074,18 +9074,18 @@
│ │ │  <a href="https://www.ietf.org/rfc/rfc2732.txt">RFC2732 </a>.</p></li></ul><p>Options:</p><ul><li><p><strong><code class="inline">{packet_size, integer() &gt;= 0}</code></strong> - Sets the maximum allowed size of the
│ │ │  packet body. If the packet header indicates that the length of the packet is
│ │ │  longer than the maximum allowed length, the packet is considered invalid.
│ │ │  Defaults to 0, which means no size limit.</p></li><li><p><strong><code class="inline">{line_length, integer() &gt;= 0}</code></strong> - For packet type <code class="inline">line</code>, lines longer
│ │ │  than the indicated length are truncated.</p><p>Option <code class="inline">line_length</code> also applies to <code class="inline">http*</code> packet types as an alias for
│ │ │  option <code class="inline">packet_size</code> if <code class="inline">packet_size</code> itself is not set. This use is only
│ │ │  intended for backward compatibility.</p></li><li><p><strong><code class="inline">{line_delimiter, 0 =&lt; byte() =&lt; 255}</code></strong> - For packet type <code class="inline">line</code>, sets the
│ │ │ -delimiting byte. Default is the latin-1 character <code class="inline">$\n</code>.</p></li></ul><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">decode_packet</span><span class="p" data-group-id="2771097736-1">(</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="2771097736-2">&lt;&lt;</span><span class="mi">3</span><span class="p">,</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="2771097736-2">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="2771097736-3">[</span><span class="p" data-group-id="2771097736-3">]</span><span class="p" data-group-id="2771097736-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2771097736-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="2771097736-5">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="2771097736-5">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="2771097736-6">&lt;&lt;</span><span class="s">&quot;d&quot;</span><span class="p" data-group-id="2771097736-6">&gt;&gt;</span><span class="p" data-group-id="2771097736-4">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">decode_packet</span><span class="p" data-group-id="2771097736-7">(</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="2771097736-8">&lt;&lt;</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="2771097736-8">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="2771097736-9">[</span><span class="p" data-group-id="2771097736-9">]</span><span class="p" data-group-id="2771097736-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2771097736-10">{</span><span class="ss">more</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2771097736-10">}</span></code></pre>
│ │ │ +delimiting byte. Default is the latin-1 character <code class="inline">$\n</code>.</p></li></ul><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">decode_packet</span><span class="p" data-group-id="5121242854-1">(</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="5121242854-2">&lt;&lt;</span><span class="mi">3</span><span class="p">,</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="5121242854-2">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="5121242854-3">[</span><span class="p" data-group-id="5121242854-3">]</span><span class="p" data-group-id="5121242854-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5121242854-4">{</span><span class="ss">ok</span><span class="p">,</span><span class="p" data-group-id="5121242854-5">&lt;&lt;</span><span class="s">&quot;abc&quot;</span><span class="p" data-group-id="5121242854-5">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="5121242854-6">&lt;&lt;</span><span class="s">&quot;d&quot;</span><span class="p" data-group-id="5121242854-6">&gt;&gt;</span><span class="p" data-group-id="5121242854-4">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">decode_packet</span><span class="p" data-group-id="5121242854-7">(</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="5121242854-8">&lt;&lt;</span><span class="mi">5</span><span class="p">,</span><span class="s">&quot;abcd&quot;</span><span class="p" data-group-id="5121242854-8">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="5121242854-9">[</span><span class="p" data-group-id="5121242854-9">]</span><span class="p" data-group-id="5121242854-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5121242854-10">{</span><span class="ss">more</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="5121242854-10">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="delete_element/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#delete_element/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9106,16 +9106,16 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> delete_element(Index, Tuple1) -> Tuple2
│ │ │                          when Index :: <a href="#t:pos_integer/0">pos_integer</a>(), Tuple1 :: <a href="#t:tuple/0">tuple</a>(), Tuple2 :: <a href="#t:tuple/0">tuple</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a new tuple with element at <code class="inline">Index</code> removed from tuple <code class="inline">Tuple1</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">delete_element</span><span class="p" data-group-id="1304428661-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1304428661-2">{</span><span class="ss">one</span><span class="p">,</span><span class="w"> </span><span class="ss">two</span><span class="p">,</span><span class="w"> </span><span class="ss">three</span><span class="p" data-group-id="1304428661-2">}</span><span class="p" data-group-id="1304428661-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1304428661-3">{</span><span class="ss">one</span><span class="p">,</span><span class="ss">three</span><span class="p" data-group-id="1304428661-3">}</span></code></pre>
│ │ │ +<p>Returns a new tuple with element at <code class="inline">Index</code> removed from tuple <code class="inline">Tuple1</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">delete_element</span><span class="p" data-group-id="0497952798-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0497952798-2">{</span><span class="ss">one</span><span class="p">,</span><span class="w"> </span><span class="ss">two</span><span class="p">,</span><span class="w"> </span><span class="ss">three</span><span class="p" data-group-id="0497952798-2">}</span><span class="p" data-group-id="0497952798-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0497952798-3">{</span><span class="ss">one</span><span class="p">,</span><span class="ss">three</span><span class="p" data-group-id="0497952798-3">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="display/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#display/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9165,15 +9165,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> element(N, Tuple) -> <a href="#t:term/0">term</a>() when N :: <a href="#t:pos_integer/0">pos_integer</a>(), Tuple :: <a href="#t:tuple/0">tuple</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the <code class="inline">N</code>th element (numbering from 1) of <code class="inline">Tuple</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">element</span><span class="p" data-group-id="6102215018-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6102215018-2">{</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="6102215018-2">}</span><span class="p" data-group-id="6102215018-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the <code class="inline">N</code>th element (numbering from 1) of <code class="inline">Tuple</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">element</span><span class="p" data-group-id="1787261502-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1787261502-2">{</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="1787261502-2">}</span><span class="p" data-group-id="1787261502-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">b</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="external_size/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#external_size/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -9195,18 +9195,18 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> external_size(Term) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Term :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Calculates, without doing the encoding, the maximum byte size for a term encoded
│ │ │ -in the Erlang external term format.</p><p>The following condition applies always:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Size1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="5333191287-1">(</span><span class="nf">term_to_binary</span><span class="p" data-group-id="5333191287-2">(</span><span class="n">Term</span><span class="p" data-group-id="5333191287-2">)</span><span class="p" data-group-id="5333191287-1">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Size2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">external_size</span><span class="p" data-group-id="5333191287-3">(</span><span class="n">Term</span><span class="p" data-group-id="5333191287-3">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │ +in the Erlang external term format.</p><p>The following condition applies always:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Size1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="9436420014-1">(</span><span class="nf">term_to_binary</span><span class="p" data-group-id="9436420014-2">(</span><span class="n">Term</span><span class="p" data-group-id="9436420014-2">)</span><span class="p" data-group-id="9436420014-1">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Size2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">external_size</span><span class="p" data-group-id="9436420014-3">(</span><span class="n">Term</span><span class="p" data-group-id="9436420014-3">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │  &gt; </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Size1</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">Size2</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="ss">true</span></code></pre><p>This is equivalent to a call to:</p><pre><code class="makeup erlang" translate="no"><span class="nc">erlang</span><span class="p">:</span><span class="nf">external_size</span><span class="p" data-group-id="8561229205-1">(</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8561229205-2">[</span><span class="p" data-group-id="8561229205-2">]</span><span class="p" data-group-id="8561229205-1">)</span></code></pre>
│ │ │ +</span><span class="ss">true</span></code></pre><p>This is equivalent to a call to:</p><pre><code class="makeup erlang" translate="no"><span class="nc">erlang</span><span class="p">:</span><span class="nf">external_size</span><span class="p" data-group-id="4097560084-1">(</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4097560084-2">[</span><span class="p" data-group-id="4097560084-2">]</span><span class="p" data-group-id="4097560084-1">)</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="external_size/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#external_size/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9235,16 +9235,16 @@
│ │ │                                  deterministic |
│ │ │                                  {minor_version, Version :: 0..2} |
│ │ │                                  local].</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Calculates, without doing the encoding, the maximum byte size for a term encoded
│ │ │ -in the Erlang external term format.</p><p>The following condition applies always:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Size1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="6522469530-1">(</span><span class="nf">term_to_binary</span><span class="p" data-group-id="6522469530-2">(</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="6522469530-2">)</span><span class="p" data-group-id="6522469530-1">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Size2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">external_size</span><span class="p" data-group-id="6522469530-3">(</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="6522469530-3">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │ +in the Erlang external term format.</p><p>The following condition applies always:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Size1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">byte_size</span><span class="p" data-group-id="7000059337-1">(</span><span class="nf">term_to_binary</span><span class="p" data-group-id="7000059337-2">(</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="7000059337-2">)</span><span class="p" data-group-id="7000059337-1">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Size2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">external_size</span><span class="p" data-group-id="7000059337-3">(</span><span class="n">Term</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="p" data-group-id="7000059337-3">)</span><span class="p">,</span><span class="gp unselectable">
│ │ │  &gt; </span><span class="ss">true</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Size1</span><span class="w"> </span><span class="o">=&lt;</span><span class="w"> </span><span class="n">Size2</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><p>Option <code class="inline">{minor_version, Version}</code> specifies how floats are encoded. For a
│ │ │  detailed description, see <a href="#term_to_binary/2"><code class="inline">term_to_binary/2</code></a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="float/1">
│ │ │  
│ │ │ @@ -9269,15 +9269,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> float(Number) -> <a href="#t:float/0">float</a>() when Number :: <a href="#t:number/0">number</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a float by converting <code class="inline">Number</code> to a float.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">float</span><span class="p" data-group-id="5724270117-1">(</span><span class="mi">55</span><span class="p" data-group-id="5724270117-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns a float by converting <code class="inline">Number</code> to a float.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">float</span><span class="p" data-group-id="4490832192-1">(</span><span class="mi">55</span><span class="p" data-group-id="4490832192-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">55.0</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>If used on the top level in a guard, it tests whether the argument is a
│ │ │  floating point number; for clarity, use <a href="#is_float/1"><code class="inline">is_float/1</code></a> instead.</p><p>When <a href="#float/1"><code class="inline">float/1</code></a> is used in an expression in a guard, such as
│ │ │  '<code class="inline">float(A) == 4.0</code>', it converts a number as described earlier.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="float_to_binary/1">
│ │ │  
│ │ │ @@ -9340,26 +9340,26 @@
│ │ │                                   {decimals, Decimals :: 0..253} |
│ │ │                                   {scientific, Decimals :: 0..249} |
│ │ │                                   compact | short.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a binary corresponding to the text representation of <code class="inline">Float</code> using fixed
│ │ │ -decimal point formatting.</p><p><code class="inline">Options</code> behaves in the same way as <a href="#float_to_list/2"><code class="inline">float_to_list/2</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="4945809201-1">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4945809201-2">[</span><span class="p" data-group-id="4945809201-3">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="4945809201-3">}</span><span class="p" data-group-id="4945809201-2">]</span><span class="p" data-group-id="4945809201-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4945809201-4">&lt;&lt;</span><span class="s">&quot;7.1200&quot;</span><span class="p" data-group-id="4945809201-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="4945809201-5">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4945809201-6">[</span><span class="p" data-group-id="4945809201-7">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="4945809201-7">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compact</span><span class="p" data-group-id="4945809201-6">]</span><span class="p" data-group-id="4945809201-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4945809201-8">&lt;&lt;</span><span class="s">&quot;7.12&quot;</span><span class="p" data-group-id="4945809201-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="4945809201-9">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4945809201-10">[</span><span class="p" data-group-id="4945809201-11">{</span><span class="ss">scientific</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="4945809201-11">}</span><span class="p" data-group-id="4945809201-10">]</span><span class="p" data-group-id="4945809201-9">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4945809201-12">&lt;&lt;</span><span class="s">&quot;7.120e+00&quot;</span><span class="p" data-group-id="4945809201-12">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="4945809201-13">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4945809201-14">[</span><span class="ss">short</span><span class="p" data-group-id="4945809201-14">]</span><span class="p" data-group-id="4945809201-13">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4945809201-15">&lt;&lt;</span><span class="s">&quot;7.12&quot;</span><span class="p" data-group-id="4945809201-15">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="4945809201-16">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4945809201-17">[</span><span class="ss">short</span><span class="p" data-group-id="4945809201-17">]</span><span class="p" data-group-id="4945809201-16">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4945809201-18">&lt;&lt;</span><span class="s">&quot;0.30000000000000004&quot;</span><span class="p" data-group-id="4945809201-18">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="4945809201-19">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p" data-group-id="4945809201-19">)</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4945809201-20">&lt;&lt;</span><span class="s">&quot;3.00000000000000044409e-01&quot;</span><span class="p" data-group-id="4945809201-20">&gt;&gt;</span></code></pre>
│ │ │ +decimal point formatting.</p><p><code class="inline">Options</code> behaves in the same way as <a href="#float_to_list/2"><code class="inline">float_to_list/2</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="2689799249-1">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2689799249-2">[</span><span class="p" data-group-id="2689799249-3">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="2689799249-3">}</span><span class="p" data-group-id="2689799249-2">]</span><span class="p" data-group-id="2689799249-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2689799249-4">&lt;&lt;</span><span class="s">&quot;7.1200&quot;</span><span class="p" data-group-id="2689799249-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="2689799249-5">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2689799249-6">[</span><span class="p" data-group-id="2689799249-7">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="2689799249-7">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compact</span><span class="p" data-group-id="2689799249-6">]</span><span class="p" data-group-id="2689799249-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2689799249-8">&lt;&lt;</span><span class="s">&quot;7.12&quot;</span><span class="p" data-group-id="2689799249-8">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="2689799249-9">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2689799249-10">[</span><span class="p" data-group-id="2689799249-11">{</span><span class="ss">scientific</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="2689799249-11">}</span><span class="p" data-group-id="2689799249-10">]</span><span class="p" data-group-id="2689799249-9">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2689799249-12">&lt;&lt;</span><span class="s">&quot;7.120e+00&quot;</span><span class="p" data-group-id="2689799249-12">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="2689799249-13">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2689799249-14">[</span><span class="ss">short</span><span class="p" data-group-id="2689799249-14">]</span><span class="p" data-group-id="2689799249-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2689799249-15">&lt;&lt;</span><span class="s">&quot;7.12&quot;</span><span class="p" data-group-id="2689799249-15">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="2689799249-16">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2689799249-17">[</span><span class="ss">short</span><span class="p" data-group-id="2689799249-17">]</span><span class="p" data-group-id="2689799249-16">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2689799249-18">&lt;&lt;</span><span class="s">&quot;0.30000000000000004&quot;</span><span class="p" data-group-id="2689799249-18">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">float_to_binary</span><span class="p" data-group-id="2689799249-19">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p" data-group-id="2689799249-19">)</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2689799249-20">&lt;&lt;</span><span class="s">&quot;3.00000000000000044409e-01&quot;</span><span class="p" data-group-id="2689799249-20">&gt;&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="float_to_list/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#float_to_list/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9427,25 +9427,25 @@
│ │ │  are truncated. This option is only meaningful together with option <code class="inline">decimals</code>.</li><li>If option <code class="inline">scientific</code> is specified, the float is formatted using scientific
│ │ │  notation with <code class="inline">Decimals</code> digits of precision.</li><li>If option <code class="inline">short</code> is specified, the float is formatted with the smallest
│ │ │  number of digits that still guarantees that
│ │ │  <code class="inline">F =:= list_to_float(float_to_list(F, [short]))</code>. When the float is inside the
│ │ │  range (-2⁵³, 2⁵³), the notation that yields the smallest number of characters
│ │ │  is used (scientific notation or normal decimal notation). Floats outside the
│ │ │  range (-2⁵³, 2⁵³) are always formatted using scientific notation to avoid
│ │ │ -confusing results when doing arithmetic operations.</li><li>If <code class="inline">Options</code> is <code class="inline">[]</code>, the function behaves as <a href="#float_to_list/1"><code class="inline">float_to_list/1</code></a>.</li></ul><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="1869446360-1">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1869446360-2">[</span><span class="p" data-group-id="1869446360-3">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="1869446360-3">}</span><span class="p" data-group-id="1869446360-2">]</span><span class="p" data-group-id="1869446360-1">)</span><span class="p">.</span><span class="w">
│ │ │ +confusing results when doing arithmetic operations.</li><li>If <code class="inline">Options</code> is <code class="inline">[]</code>, the function behaves as <a href="#float_to_list/1"><code class="inline">float_to_list/1</code></a>.</li></ul><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="2356857659-1">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2356857659-2">[</span><span class="p" data-group-id="2356857659-3">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="2356857659-3">}</span><span class="p" data-group-id="2356857659-2">]</span><span class="p" data-group-id="2356857659-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;7.1200&quot;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="1869446360-4">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1869446360-5">[</span><span class="p" data-group-id="1869446360-6">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="1869446360-6">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compact</span><span class="p" data-group-id="1869446360-5">]</span><span class="p" data-group-id="1869446360-4">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="2356857659-4">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2356857659-5">[</span><span class="p" data-group-id="2356857659-6">{</span><span class="ss">decimals</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p" data-group-id="2356857659-6">}</span><span class="p">,</span><span class="w"> </span><span class="ss">compact</span><span class="p" data-group-id="2356857659-5">]</span><span class="p" data-group-id="2356857659-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;7.12&quot;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="1869446360-7">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1869446360-8">[</span><span class="p" data-group-id="1869446360-9">{</span><span class="ss">scientific</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="1869446360-9">}</span><span class="p" data-group-id="1869446360-8">]</span><span class="p" data-group-id="1869446360-7">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="2356857659-7">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2356857659-8">[</span><span class="p" data-group-id="2356857659-9">{</span><span class="ss">scientific</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="2356857659-9">}</span><span class="p" data-group-id="2356857659-8">]</span><span class="p" data-group-id="2356857659-7">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;7.120e+00&quot;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="1869446360-10">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1869446360-11">[</span><span class="ss">short</span><span class="p" data-group-id="1869446360-11">]</span><span class="p" data-group-id="1869446360-10">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="2356857659-10">(</span><span class="mf">7.12</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2356857659-11">[</span><span class="ss">short</span><span class="p" data-group-id="2356857659-11">]</span><span class="p" data-group-id="2356857659-10">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;7.12&quot;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="1869446360-12">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1869446360-13">[</span><span class="ss">short</span><span class="p" data-group-id="1869446360-13">]</span><span class="p" data-group-id="1869446360-12">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="2356857659-12">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2356857659-13">[</span><span class="ss">short</span><span class="p" data-group-id="2356857659-13">]</span><span class="p" data-group-id="2356857659-12">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;0.30000000000000004&quot;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="1869446360-14">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p" data-group-id="1869446360-14">)</span><span class="w">
│ │ │ +&gt; </span><span class="nf">float_to_list</span><span class="p" data-group-id="2356857659-14">(</span><span class="mf">0.1</span><span class="o">+</span><span class="mf">0.2</span><span class="p" data-group-id="2356857659-14">)</span><span class="w">
│ │ │  </span><span class="s">&quot;3.00000000000000044409e-01&quot;</span></code></pre><p>In the last example, <a href="#float_to_list/1"><code class="inline">float_to_list(0.1+0.2)</code></a> evaluates to
│ │ │  <code class="inline">&quot;3.00000000000000044409e-01&quot;</code>. The reason for this is explained in
│ │ │  <a href="../../../doc/system/data_types.html#float_representation_problem">Representation of Floating Point Numbers</a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="floor/1">
│ │ │  
│ │ │ @@ -9472,15 +9472,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> floor(Number) -> <a href="#t:integer/0">integer</a>() when Number :: <a href="#t:number/0">number</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the largest integer not greater than <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">floor</span><span class="p" data-group-id="8307209643-1">(</span><span class="o">-</span><span class="mf">10.5</span><span class="p" data-group-id="8307209643-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the largest integer not greater than <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">floor</span><span class="p" data-group-id="2702854584-1">(</span><span class="o">-</span><span class="mf">10.5</span><span class="p" data-group-id="2702854584-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">-</span><span class="mi">11</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="fun_info/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#fun_info/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -9600,25 +9600,25 @@
│ │ │  named <code class="inline">module</code>, <code class="inline">index</code> and <code class="inline">uniq</code> in the result of
│ │ │  <a href="#fun_info/1"><code class="inline">erlang:fun_info(Fun)</code></a>.</p></li><li><p><strong>uncompiled code</strong> - All funs created from fun expressions in uncompiled code
│ │ │  with the same arity are mapped to the same list by
│ │ │  <a href="#fun_to_list/1"><code class="inline">fun_to_list/1</code></a>.</p></li></ul><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Generally, one can not use <a href="#fun_to_list/1"><code class="inline">fun_to_list/1</code></a> to check if two
│ │ │  funs are equal as <a href="#fun_to_list/1"><code class="inline">fun_to_list/1</code></a> does not take the fun's
│ │ │  environment into account. See <a href="#fun_info/1"><code class="inline">erlang:fun_info/1</code></a> for how to
│ │ │  get the environment of a fun.</p></section><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>The output of <a href="#fun_to_list/1"><code class="inline">fun_to_list/1</code></a> can differ between Erlang
│ │ │ -implementations and may change in future versions.</p></section><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1312870903-1">(</span><span class="ss">test</span><span class="p" data-group-id="1312870903-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1312870903-2">(</span><span class="p" data-group-id="1312870903-3">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">add2</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">fun_tuple</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1312870903-3">]</span><span class="p" data-group-id="1312870903-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add</span><span class="p" data-group-id="1312870903-4">(</span><span class="n">A</span><span class="p" data-group-id="1312870903-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1312870903-5">(</span><span class="n">B</span><span class="p" data-group-id="1312870903-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">add2</span><span class="p" data-group-id="1312870903-6">(</span><span class="p" data-group-id="1312870903-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="nf">fun_tuple</span><span class="p" data-group-id="1312870903-7">(</span><span class="p" data-group-id="1312870903-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1312870903-8">{</span><span class="nf">fun</span><span class="p" data-group-id="1312870903-9">(</span><span class="p" data-group-id="1312870903-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1312870903-10">(</span><span class="p" data-group-id="1312870903-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="1312870903-8">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="7496826428-1">{</span><span class="k">fun</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="nf">add2</span><span class="p" data-group-id="7496826428-2">(</span><span class="p" data-group-id="7496826428-2">)</span><span class="p" data-group-id="7496826428-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7496826428-3">{</span><span class="k">fun</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">1.107738983</span><span class="o">&gt;</span><span class="p" data-group-id="7496826428-3">}</span></code></pre><p>Explanation: <code class="inline">fun test:add/1</code> is upgradable but <code class="inline">test:add2()</code> is not upgradable.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="2100314367-1">{</span><span class="nc">test</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="2100314367-2">(</span><span class="mi">1</span><span class="p" data-group-id="2100314367-2">)</span><span class="p">,</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="2100314367-3">(</span><span class="mi">42</span><span class="p" data-group-id="2100314367-3">)</span><span class="p" data-group-id="2100314367-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2100314367-4">{</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">0.107738983</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">0.107738983</span><span class="o">&gt;</span><span class="p" data-group-id="2100314367-4">}</span></code></pre><p>Explanation: <code class="inline">test:add(1)</code> and <code class="inline">test:add(42)</code> has the same string representation
│ │ │ -as the environment is not taken into account.</p><pre><code class="makeup erlang" translate="no"><span class="o">&gt;</span><span class="nc">test</span><span class="p">:</span><span class="nf">fun_tuple</span><span class="p" data-group-id="6216079199-1">(</span><span class="p" data-group-id="6216079199-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6216079199-2">{</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">2.107738983</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">3.107738983</span><span class="o">&gt;</span><span class="p" data-group-id="6216079199-2">}</span></code></pre><p>Explanation: The string representations differ because the funs come from
│ │ │ -different fun expressions.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="0502615976-1">{</span><span class="nf">fun</span><span class="p" data-group-id="0502615976-2">(</span><span class="p" data-group-id="0502615976-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="0502615976-3">(</span><span class="p" data-group-id="0502615976-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="0502615976-1">}</span><span class="p">.</span><span class="w"> </span><span class="o">&gt;</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0502615976-4">{</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">45.97283095</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">45.97283095</span><span class="o">&gt;</span><span class="p" data-group-id="0502615976-4">}</span></code></pre><p>Explanation: All funs created from fun expressions of this form in uncompiled
│ │ │ +implementations and may change in future versions.</p></section><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="1327570299-1">(</span><span class="ss">test</span><span class="p" data-group-id="1327570299-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="1327570299-2">(</span><span class="p" data-group-id="1327570299-3">[</span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">add2</span><span class="p">/</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="ss">fun_tuple</span><span class="p">/</span><span class="mi">0</span><span class="p" data-group-id="1327570299-3">]</span><span class="p" data-group-id="1327570299-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add</span><span class="p" data-group-id="1327570299-4">(</span><span class="n">A</span><span class="p" data-group-id="1327570299-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1327570299-5">(</span><span class="n">B</span><span class="p" data-group-id="1327570299-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="k">end</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">add2</span><span class="p" data-group-id="1327570299-6">(</span><span class="p" data-group-id="1327570299-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">fun_tuple</span><span class="p" data-group-id="1327570299-7">(</span><span class="p" data-group-id="1327570299-7">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1327570299-8">{</span><span class="nf">fun</span><span class="p" data-group-id="1327570299-9">(</span><span class="p" data-group-id="1327570299-9">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="1327570299-10">(</span><span class="p" data-group-id="1327570299-10">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="1327570299-8">}</span><span class="p">.</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="2301446964-1">{</span><span class="k">fun</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="nf">add2</span><span class="p" data-group-id="2301446964-2">(</span><span class="p" data-group-id="2301446964-2">)</span><span class="p" data-group-id="2301446964-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2301446964-3">{</span><span class="k">fun</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="ss">add</span><span class="p">/</span><span class="mi">1</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">1.107738983</span><span class="o">&gt;</span><span class="p" data-group-id="2301446964-3">}</span></code></pre><p>Explanation: <code class="inline">fun test:add/1</code> is upgradable but <code class="inline">test:add2()</code> is not upgradable.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="2259653731-1">{</span><span class="nc">test</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="2259653731-2">(</span><span class="mi">1</span><span class="p" data-group-id="2259653731-2">)</span><span class="p">,</span><span class="w"> </span><span class="nc">test</span><span class="p">:</span><span class="nf">add</span><span class="p" data-group-id="2259653731-3">(</span><span class="mi">42</span><span class="p" data-group-id="2259653731-3">)</span><span class="p" data-group-id="2259653731-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2259653731-4">{</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">0.107738983</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">0.107738983</span><span class="o">&gt;</span><span class="p" data-group-id="2259653731-4">}</span></code></pre><p>Explanation: <code class="inline">test:add(1)</code> and <code class="inline">test:add(42)</code> has the same string representation
│ │ │ +as the environment is not taken into account.</p><pre><code class="makeup erlang" translate="no"><span class="o">&gt;</span><span class="nc">test</span><span class="p">:</span><span class="nf">fun_tuple</span><span class="p" data-group-id="6627022900-1">(</span><span class="p" data-group-id="6627022900-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6627022900-2">{</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">2.107738983</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">test</span><span class="p">.</span><span class="mf">3.107738983</span><span class="o">&gt;</span><span class="p" data-group-id="6627022900-2">}</span></code></pre><p>Explanation: The string representations differ because the funs come from
│ │ │ +different fun expressions.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="8073882535-1">{</span><span class="nf">fun</span><span class="p" data-group-id="8073882535-2">(</span><span class="p" data-group-id="8073882535-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nf">fun</span><span class="p" data-group-id="8073882535-3">(</span><span class="p" data-group-id="8073882535-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="k">end</span><span class="p" data-group-id="8073882535-1">}</span><span class="p">.</span><span class="w"> </span><span class="o">&gt;</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8073882535-4">{</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">45.97283095</span><span class="o">&gt;</span><span class="p">,</span><span class="p">#</span><span class="n">Fun</span><span class="o">&lt;</span><span class="ss">erl_eval</span><span class="p">.</span><span class="mf">45.97283095</span><span class="o">&gt;</span><span class="p" data-group-id="8073882535-4">}</span></code></pre><p>Explanation: All funs created from fun expressions of this form in uncompiled
│ │ │  code with the same arity are mapped to the same list by
│ │ │  <a href="#fun_to_list/1"><code class="inline">fun_to_list/1</code></a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="hd/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -9642,16 +9642,16 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> hd(List) -> Head when List :: <a href="#t:nonempty_maybe_improper_list/0">nonempty_maybe_improper_list</a>(), Head :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the head of <code class="inline">List</code>, that is, the first element.</p><p>It works with improper lists.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">hd</span><span class="p" data-group-id="4602920584-1">(</span><span class="p" data-group-id="4602920584-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4602920584-2">]</span><span class="p" data-group-id="4602920584-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">hd</span><span class="p" data-group-id="2867143431-1">(</span><span class="p" data-group-id="2867143431-2">[</span><span class="ss">first</span><span class="p">,</span><span class="w"> </span><span class="ss">second</span><span class="p">,</span><span class="w"> </span><span class="ss">third</span><span class="p">,</span><span class="w"> </span><span class="ss">so_on</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="2867143431-2">]</span><span class="p" data-group-id="2867143431-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the head of <code class="inline">List</code>, that is, the first element.</p><p>It works with improper lists.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">hd</span><span class="p" data-group-id="5175425019-1">(</span><span class="p" data-group-id="5175425019-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="5175425019-2">]</span><span class="p" data-group-id="5175425019-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">hd</span><span class="p" data-group-id="0082924862-1">(</span><span class="p" data-group-id="0082924862-2">[</span><span class="ss">first</span><span class="p">,</span><span class="w"> </span><span class="ss">second</span><span class="p">,</span><span class="w"> </span><span class="ss">third</span><span class="p">,</span><span class="w"> </span><span class="ss">so_on</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="0082924862-2">]</span><span class="p" data-group-id="0082924862-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">first</span></code></pre><p>Failure: <code class="inline">badarg</code> if <code class="inline">List</code> is an empty list <code class="inline">[]</code>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="insert_element/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#insert_element/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -9676,16 +9676,16 @@
│ │ │                          when
│ │ │                              Index :: <a href="#t:pos_integer/0">pos_integer</a>(), Tuple1 :: <a href="#t:tuple/0">tuple</a>(), Tuple2 :: <a href="#t:tuple/0">tuple</a>(), Term :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a new tuple with element <code class="inline">Term</code> inserted at position <code class="inline">Index</code> in tuple
│ │ │  <code class="inline">Tuple1</code>. All elements from position <code class="inline">Index</code> and upwards are pushed one step
│ │ │ -higher in the new tuple <code class="inline">Tuple2</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">insert_element</span><span class="p" data-group-id="4115300618-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4115300618-2">{</span><span class="ss">one</span><span class="p">,</span><span class="w"> </span><span class="ss">two</span><span class="p">,</span><span class="w"> </span><span class="ss">three</span><span class="p" data-group-id="4115300618-2">}</span><span class="p">,</span><span class="w"> </span><span class="ss">new</span><span class="p" data-group-id="4115300618-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4115300618-3">{</span><span class="ss">one</span><span class="p">,</span><span class="ss">new</span><span class="p">,</span><span class="ss">two</span><span class="p">,</span><span class="ss">three</span><span class="p" data-group-id="4115300618-3">}</span></code></pre>
│ │ │ +higher in the new tuple <code class="inline">Tuple2</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">insert_element</span><span class="p" data-group-id="9369493186-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9369493186-2">{</span><span class="ss">one</span><span class="p">,</span><span class="w"> </span><span class="ss">two</span><span class="p">,</span><span class="w"> </span><span class="ss">three</span><span class="p" data-group-id="9369493186-2">}</span><span class="p">,</span><span class="w"> </span><span class="ss">new</span><span class="p" data-group-id="9369493186-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9369493186-3">{</span><span class="ss">one</span><span class="p">,</span><span class="ss">new</span><span class="p">,</span><span class="ss">two</span><span class="p">,</span><span class="ss">three</span><span class="p" data-group-id="9369493186-3">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="integer_to_binary/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#integer_to_binary/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9707,16 +9707,16 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> integer_to_binary(Integer) -> <a href="#t:binary/0">binary</a>() when Integer :: <a href="#t:integer/0">integer</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a binary corresponding to the text representation of <code class="inline">Integer</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="1451969158-1">(</span><span class="mi">77</span><span class="p" data-group-id="1451969158-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1451969158-2">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="1451969158-2">&gt;&gt;</span></code></pre>
│ │ │ +<p>Returns a binary corresponding to the text representation of <code class="inline">Integer</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="8749364148-1">(</span><span class="mi">77</span><span class="p" data-group-id="8749364148-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8749364148-2">&lt;&lt;</span><span class="s">&quot;77&quot;</span><span class="p" data-group-id="8749364148-2">&gt;&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="integer_to_binary/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#integer_to_binary/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9739,16 +9739,16 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> integer_to_binary(Integer, Base) -> <a href="#t:binary/0">binary</a>() when Integer :: <a href="#t:integer/0">integer</a>(), Base :: 2..36.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a binary corresponding to the text representation of <code class="inline">Integer</code> in base
│ │ │ -<code class="inline">Base</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="2412565842-1">(</span><span class="mi">1023</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="2412565842-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2412565842-2">&lt;&lt;</span><span class="s">&quot;3FF&quot;</span><span class="p" data-group-id="2412565842-2">&gt;&gt;</span></code></pre>
│ │ │ +<code class="inline">Base</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_binary</span><span class="p" data-group-id="3814431822-1">(</span><span class="mi">1023</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="3814431822-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3814431822-2">&lt;&lt;</span><span class="s">&quot;3FF&quot;</span><span class="p" data-group-id="3814431822-2">&gt;&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="integer_to_list/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#integer_to_list/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9768,15 +9768,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> integer_to_list(Integer) -> <a href="#t:string/0">string</a>() when Integer :: <a href="#t:integer/0">integer</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a string corresponding to the text representation of <code class="inline">Integer</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="8584632256-1">(</span><span class="mi">77</span><span class="p" data-group-id="8584632256-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns a string corresponding to the text representation of <code class="inline">Integer</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="6001458269-1">(</span><span class="mi">77</span><span class="p" data-group-id="6001458269-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;77&quot;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="integer_to_list/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#integer_to_list/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -9798,15 +9798,15 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> integer_to_list(Integer, Base) -> <a href="#t:string/0">string</a>() when Integer :: <a href="#t:integer/0">integer</a>(), Base :: 2..36.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a string corresponding to the text representation of <code class="inline">Integer</code> in base
│ │ │ -<code class="inline">Base</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="5013497612-1">(</span><span class="mi">1023</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="5013497612-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">Base</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">integer_to_list</span><span class="p" data-group-id="7306089258-1">(</span><span class="mi">1023</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="7306089258-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;3FF&quot;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="iolist_size/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#iolist_size/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -9828,15 +9828,15 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> iolist_size(Item) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Item :: <a href="#t:iolist/0">iolist</a>() | <a href="#t:binary/0">binary</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns an integer, that is the size in bytes, of the binary that would be the
│ │ │ -result of <a href="#iolist_to_binary/1"><code class="inline">iolist_to_binary(Item)</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">iolist_size</span><span class="p" data-group-id="9175934317-1">(</span><span class="p" data-group-id="9175934317-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">|</span><span class="p" data-group-id="9175934317-3">&lt;&lt;</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="9175934317-3">&gt;&gt;</span><span class="p" data-group-id="9175934317-2">]</span><span class="p" data-group-id="9175934317-1">)</span><span class="p">.</span><span class="w">
│ │ │ +result of <a href="#iolist_to_binary/1"><code class="inline">iolist_to_binary(Item)</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">iolist_size</span><span class="p" data-group-id="4401338052-1">(</span><span class="p" data-group-id="4401338052-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">|</span><span class="p" data-group-id="4401338052-3">&lt;&lt;</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p" data-group-id="4401338052-3">&gt;&gt;</span><span class="p" data-group-id="4401338052-2">]</span><span class="p" data-group-id="4401338052-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">4</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="iolist_to_binary/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#iolist_to_binary/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -9858,22 +9858,22 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> iolist_to_binary(IoListOrBinary) -> <a href="#t:binary/0">binary</a>() when IoListOrBinary :: <a href="#t:iolist/0">iolist</a>() | <a href="#t:binary/0">binary</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a binary that is made from the integers and binaries in
│ │ │ -<code class="inline">IoListOrBinary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8592102420-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8592102420-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8592102420-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8592102420-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8592102420-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8592102420-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8592102420-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="8592102420-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="8592102420-5">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="8592102420-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8592102420-6">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="8592102420-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">iolist_to_binary</span><span class="p" data-group-id="8592102420-7">(</span><span class="p" data-group-id="8592102420-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="8592102420-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="8592102420-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="8592102420-8">]</span><span class="p" data-group-id="8592102420-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8592102420-10">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="8592102420-10">&gt;&gt;</span></code></pre>
│ │ │ +<code class="inline">IoListOrBinary</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3680913981-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3680913981-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3680913981-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3680913981-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3680913981-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3680913981-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3680913981-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3680913981-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3680913981-5">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="3680913981-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3680913981-6">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="3680913981-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">iolist_to_binary</span><span class="p" data-group-id="3680913981-7">(</span><span class="p" data-group-id="3680913981-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3680913981-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="3680913981-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="3680913981-8">]</span><span class="p" data-group-id="3680913981-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3680913981-10">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3680913981-10">&gt;&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="iolist_to_iovec/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#iolist_to_iovec/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -9899,31 +9899,31 @@
│ │ │  
│ │ │  <p>Returns an <a href="#t:iovec/0">iovec</a> that is made from the integers and binaries in
│ │ │  <code class="inline">IoListOrBinary</code>. This function is useful when you want to flatten an iolist but
│ │ │  you do not need a single binary. This can be useful for passing the data to nif
│ │ │  functions such as <a href="erl_nif.html#enif_inspect_iovec"><code class="inline">enif_inspect_iovec</code></a> or do
│ │ │  more efficient message passing. The advantage of using this function over
│ │ │  <a href="#iolist_to_binary/1"><code class="inline">iolist_to_binary/1</code></a> is that it does not have to copy
│ │ │ -<a href="../../../doc/system/binaryhandling.html#refc_binary">off-heap binaries</a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1000387934-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1000387934-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1000387934-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1000387934-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1000387934-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="1000387934-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1000387934-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="1000387934-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1000387934-5">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="1000387934-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1000387934-6">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="1000387934-6">&gt;&gt;</span><span class="w">
│ │ │ +<a href="../../../doc/system/binaryhandling.html#refc_binary">off-heap binaries</a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2139384143-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2139384143-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2139384143-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="2139384143-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2139384143-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2139384143-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2139384143-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="2139384143-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="2139384143-5">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="2139384143-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2139384143-6">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="2139384143-6">&gt;&gt;</span><span class="w">
│ │ │  </span><span class="c1">%% If you pass small binaries and integers it works as iolist_to_binary</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">iolist_to_iovec</span><span class="p" data-group-id="1000387934-7">(</span><span class="p" data-group-id="1000387934-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="1000387934-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="1000387934-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="1000387934-8">]</span><span class="p" data-group-id="1000387934-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1000387934-10">[</span><span class="p" data-group-id="1000387934-11">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="1000387934-11">&gt;&gt;</span><span class="p" data-group-id="1000387934-10">]</span><span class="w">
│ │ │ +&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">iolist_to_iovec</span><span class="p" data-group-id="2139384143-7">(</span><span class="p" data-group-id="2139384143-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="2139384143-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="2139384143-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="2139384143-8">]</span><span class="p" data-group-id="2139384143-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2139384143-10">[</span><span class="p" data-group-id="2139384143-11">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="2139384143-11">&gt;&gt;</span><span class="p" data-group-id="2139384143-10">]</span><span class="w">
│ │ │  </span><span class="c1">%% If you pass larger binaries, they are split and returned in a form</span><span class="w">
│ │ │  </span><span class="c1">%% optimized for calling the C function writev.</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">iolist_to_iovec</span><span class="p" data-group-id="1000387934-12">(</span><span class="p" data-group-id="1000387934-13">[</span><span class="p" data-group-id="1000387934-14">&lt;&lt;</span><span class="mi">1</span><span class="p" data-group-id="1000387934-14">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="1000387934-15">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">8096</span><span class="p" data-group-id="1000387934-15">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="1000387934-16">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">8096</span><span class="p" data-group-id="1000387934-16">&gt;&gt;</span><span class="p" data-group-id="1000387934-13">]</span><span class="p" data-group-id="1000387934-12">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1000387934-17">[</span><span class="p" data-group-id="1000387934-18">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="mi">0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1000387934-18">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1000387934-19">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1000387934-19">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="1000387934-20">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="1000387934-20">&gt;&gt;</span><span class="p" data-group-id="1000387934-17">]</span></code></pre>
│ │ │ +&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">iolist_to_iovec</span><span class="p" data-group-id="2139384143-12">(</span><span class="p" data-group-id="2139384143-13">[</span><span class="p" data-group-id="2139384143-14">&lt;&lt;</span><span class="mi">1</span><span class="p" data-group-id="2139384143-14">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="2139384143-15">&lt;&lt;</span><span class="mi">2</span><span class="p">:</span><span class="mi">8096</span><span class="p" data-group-id="2139384143-15">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="2139384143-16">&lt;&lt;</span><span class="mi">3</span><span class="p">:</span><span class="mi">8096</span><span class="p" data-group-id="2139384143-16">&gt;&gt;</span><span class="p" data-group-id="2139384143-13">]</span><span class="p" data-group-id="2139384143-12">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2139384143-17">[</span><span class="p" data-group-id="2139384143-18">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="mi">0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2139384143-18">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2139384143-19">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="w">
│ │ │ +   </span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2139384143-19">&gt;&gt;</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="2139384143-20">&lt;&lt;</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="2139384143-20">&gt;&gt;</span><span class="p" data-group-id="2139384143-17">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="is_atom/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#is_atom/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -10253,19 +10253,19 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> is_map_key(Key, Map) -> <a href="#t:boolean/0">boolean</a>() when Key :: <a href="#t:term/0">term</a>(), Map :: <a href="#t:map/0">map</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns <code class="inline">true</code> if map <code class="inline">Map</code> contains <code class="inline">Key</code> and returns <code class="inline">false</code> if it does not
│ │ │ -contain the <code class="inline">Key</code>.</p><p>The call fails with a <code class="inline">{badmap,Map}</code> exception if <code class="inline">Map</code> is not a map.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1762441035-1">#{</span><span class="s">&quot;42&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="1762441035-1">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1762441035-2">#{</span><span class="s">&quot;42&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="1762441035-2">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">is_map_key</span><span class="p" data-group-id="1762441035-3">(</span><span class="s">&quot;42&quot;</span><span class="p">,</span><span class="n">Map</span><span class="p" data-group-id="1762441035-3">)</span><span class="p">.</span><span class="w">
│ │ │ +contain the <code class="inline">Key</code>.</p><p>The call fails with a <code class="inline">{badmap,Map}</code> exception if <code class="inline">Map</code> is not a map.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6877293920-1">#{</span><span class="s">&quot;42&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="6877293920-1">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6877293920-2">#{</span><span class="s">&quot;42&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value</span><span class="p" data-group-id="6877293920-2">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">is_map_key</span><span class="p" data-group-id="6877293920-3">(</span><span class="s">&quot;42&quot;</span><span class="p">,</span><span class="n">Map</span><span class="p" data-group-id="6877293920-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">is_map_key</span><span class="p" data-group-id="1762441035-4">(</span><span class="ss">value</span><span class="p">,</span><span class="n">Map</span><span class="p" data-group-id="1762441035-4">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">is_map_key</span><span class="p" data-group-id="6877293920-4">(</span><span class="ss">value</span><span class="p">,</span><span class="n">Map</span><span class="p" data-group-id="6877293920-4">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="is_number/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#is_number/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -10508,15 +10508,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> length(List) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when List :: [<a href="#t:term/0">term</a>()].</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the length of <code class="inline">List</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">length</span><span class="p" data-group-id="4540071752-1">(</span><span class="p" data-group-id="4540071752-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p" data-group-id="4540071752-2">]</span><span class="p" data-group-id="4540071752-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the length of <code class="inline">List</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">length</span><span class="p" data-group-id="4389428200-1">(</span><span class="p" data-group-id="4389428200-2">[</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">8</span><span class="p">,</span><span class="mi">9</span><span class="p" data-group-id="4389428200-2">]</span><span class="p" data-group-id="4389428200-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">9</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_atom/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#list_to_atom/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -10546,15 +10546,15 @@
│ │ │  Unicode characters above 255.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The number of characters that are permitted in an atom name is limited. The
│ │ │  default limits can be found in the
│ │ │  <a href="../../../doc/system/system_limits.html">efficiency guide (section System Limits)</a>.</p></section><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>There is a <a href="../../../doc/system/system_limits.html#atoms">configurable limit</a>
│ │ │  on how many atoms that can exist and atoms are not
│ │ │  garbage collected. Therefore, it is recommended to consider if
│ │ │  <a href="#list_to_existing_atom/1"><code class="inline">list_to_existing_atom/1</code></a> is a better option than
│ │ │  <a href="#list_to_atom/1"><code class="inline">list_to_atom/1</code></a>. The default limits can be found in the
│ │ │ -<a href="../../../doc/system/system_limits.html">Efficiency Guide (section System Limits)</a>.</p></section><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="0033613107-1">(</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="0033613107-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<a href="../../../doc/system/system_limits.html">Efficiency Guide (section System Limits)</a>.</p></section><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_atom</span><span class="p" data-group-id="0177397240-1">(</span><span class="s">&quot;Erlang&quot;</span><span class="p" data-group-id="0177397240-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">&#39;Erlang&#39;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_binary/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#list_to_binary/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -10575,22 +10575,22 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_binary(IoList) -> <a href="#t:binary/0">binary</a>() when IoList :: <a href="#t:iolist/0">iolist</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a binary that is made from the integers and binaries in <code class="inline">IoList</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3325069918-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3325069918-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3325069918-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3325069918-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3325069918-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3325069918-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3325069918-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="3325069918-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="3325069918-5">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="3325069918-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3325069918-6">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="3325069918-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">list_to_binary</span><span class="p" data-group-id="3325069918-7">(</span><span class="p" data-group-id="3325069918-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="3325069918-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="3325069918-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="3325069918-8">]</span><span class="p" data-group-id="3325069918-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="3325069918-10">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="3325069918-10">&gt;&gt;</span></code></pre>
│ │ │ +<p>Returns a binary that is made from the integers and binaries in <code class="inline">IoList</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6820874572-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="6820874572-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6820874572-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="6820874572-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6820874572-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6820874572-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6820874572-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="6820874572-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6820874572-5">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="6820874572-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6820874572-6">&lt;&lt;</span><span class="mi">6</span><span class="p" data-group-id="6820874572-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">list_to_binary</span><span class="p" data-group-id="6820874572-7">(</span><span class="p" data-group-id="6820874572-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="6820874572-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="6820874572-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="6820874572-8">]</span><span class="p" data-group-id="6820874572-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="6820874572-10">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p" data-group-id="6820874572-10">&gt;&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_bitstring/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#list_to_bitstring/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -10612,22 +10612,22 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_bitstring(BitstringList) -> <a href="#t:bitstring/0">bitstring</a>() when BitstringList :: <a href="#t:bitstring_list/0">bitstring_list</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a bitstring that is made from the integers and bitstrings in
│ │ │  <code class="inline">BitstringList</code>. (The last tail in <code class="inline">BitstringList</code> is allowed to be a
│ │ │ -bitstring.)</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4694871468-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4694871468-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4694871468-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="4694871468-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4694871468-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4694871468-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4694871468-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="4694871468-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="4694871468-5">&lt;&lt;</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="4694871468-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4694871468-6">&lt;&lt;</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="4694871468-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">list_to_bitstring</span><span class="p" data-group-id="4694871468-7">(</span><span class="p" data-group-id="4694871468-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="4694871468-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="4694871468-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="4694871468-8">]</span><span class="p" data-group-id="4694871468-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4694871468-10">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="4694871468-10">&gt;&gt;</span></code></pre>
│ │ │ +bitstring.)</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7629680451-1">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7629680451-1">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7629680451-2">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7629680451-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7629680451-3">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7629680451-3">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7629680451-4">&lt;&lt;</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p" data-group-id="7629680451-4">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="n">Bin3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="7629680451-5">&lt;&lt;</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="7629680451-5">&gt;&gt;</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7629680451-6">&lt;&lt;</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="7629680451-6">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">list_to_bitstring</span><span class="p" data-group-id="7629680451-7">(</span><span class="p" data-group-id="7629680451-8">[</span><span class="n">Bin1</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="p" data-group-id="7629680451-9">[</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="n">Bin2</span><span class="p" data-group-id="7629680451-9">]</span><span class="p">,</span><span class="mi">4</span><span class="p">|</span><span class="n">Bin3</span><span class="p" data-group-id="7629680451-8">]</span><span class="p" data-group-id="7629680451-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7629680451-10">&lt;&lt;</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="mi">7</span><span class="p">:</span><span class="mi">4</span><span class="p" data-group-id="7629680451-10">&gt;&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_existing_atom/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#list_to_existing_atom/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -10683,15 +10683,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_float(String) -> <a href="#t:float/0">float</a>() when String :: <a href="#t:string/0">string</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the float whose text representation is <code class="inline">String</code>. </p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_float</span><span class="p" data-group-id="5277466846-1">(</span><span class="s">&quot;2.2017764e+0&quot;</span><span class="p" data-group-id="5277466846-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the float whose text representation is <code class="inline">String</code>. </p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_float</span><span class="p" data-group-id="1778848723-1">(</span><span class="s">&quot;2.2017764e+0&quot;</span><span class="p" data-group-id="1778848723-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">2.2017764</span></code></pre><p>The float string format is the same as the format for
│ │ │  <a href="../../../doc/system/data_types.html">Erlang float literals</a> except for that underscores
│ │ │  are not permitted.</p><p>Failure: <code class="inline">badarg</code> if <code class="inline">String</code> contains a bad representation of a float.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_integer/1">
│ │ │  
│ │ │ @@ -10714,17 +10714,17 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_integer(String) -> <a href="#t:integer/0">integer</a>() when String :: <a href="#t:string/0">string</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer whose text representation is <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="5748224061-1">(</span><span class="s">&quot;123&quot;</span><span class="p" data-group-id="5748224061-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">123</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="0378519164-1">(</span><span class="s">&quot;-123&quot;</span><span class="p" data-group-id="0378519164-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">-</span><span class="mi">123</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="0022837754-1">(</span><span class="s">&quot;+123234982304982309482093833234234&quot;</span><span class="p" data-group-id="0022837754-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer whose text representation is <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="0847116015-1">(</span><span class="s">&quot;123&quot;</span><span class="p" data-group-id="0847116015-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">123</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="9377834143-1">(</span><span class="s">&quot;-123&quot;</span><span class="p" data-group-id="9377834143-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">-</span><span class="mi">123</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="9776663199-1">(</span><span class="s">&quot;+123234982304982309482093833234234&quot;</span><span class="p" data-group-id="9776663199-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">123234982304982309482093833234234</span></code></pre><p><code class="inline">String</code> must contain at least one digit character and can have an optional
│ │ │  prefix consisting of a single &quot;<code class="inline">+</code>&quot; or &quot;<code class="inline">-</code>&quot; character (that is, <code class="inline">String</code> must
│ │ │  match the regular expression <code class="inline">&quot;^[+-]?[0-9]+$&quot;</code>).</p><p>Failure: <code class="inline">badarg</code> if <code class="inline">String</code> contains a bad representation of an integer.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_integer/2">
│ │ │  
│ │ │ @@ -10747,19 +10747,19 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_integer(String, Base) -> <a href="#t:integer/0">integer</a>() when String :: <a href="#t:string/0">string</a>(), Base :: 2..36.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer whose text representation in base <code class="inline">Base</code> is <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="1697016962-1">(</span><span class="s">&quot;3FF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="1697016962-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="4575367978-1">(</span><span class="s">&quot;+3FF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="4575367978-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="7681385362-1">(</span><span class="s">&quot;3ff&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="7681385362-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="0361724297-1">(</span><span class="s">&quot;3fF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="0361724297-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="0518257416-1">(</span><span class="s">&quot;-3FF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="0518257416-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer whose text representation in base <code class="inline">Base</code> is <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="2744217180-1">(</span><span class="s">&quot;3FF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="2744217180-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="8991048058-1">(</span><span class="s">&quot;+3FF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="8991048058-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="5363055717-1">(</span><span class="s">&quot;3ff&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="5363055717-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="9799474446-1">(</span><span class="s">&quot;3fF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="9799474446-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1023</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_integer</span><span class="p" data-group-id="8117576711-1">(</span><span class="s">&quot;-3FF&quot;</span><span class="p">,</span><span class="w"> </span><span class="mi">16</span><span class="p" data-group-id="8117576711-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">-</span><span class="mi">1023</span></code></pre><p>For example, when <code class="inline">Base</code> is 16, <code class="inline">String</code> must match the regular expression
│ │ │  <code class="inline">&quot;^[+-]?([0-9]|[A-F]|[a-f])+$&quot;</code>.</p><p>Failure: <code class="inline">badarg</code> if <code class="inline">String</code> contains a bad representation of an integer.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_pid/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -10781,15 +10781,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_pid(String) -> <a href="#t:pid/0">pid</a>() when String :: <a href="#t:string/0">string</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a process identifier whose text representation is a <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_pid</span><span class="p" data-group-id="0488037862-1">(</span><span class="s">&quot;&lt;0.4.1&gt;&quot;</span><span class="p" data-group-id="0488037862-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns a process identifier whose text representation is a <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_pid</span><span class="p" data-group-id="0097245080-1">(</span><span class="s">&quot;&lt;0.4.1&gt;&quot;</span><span class="p" data-group-id="0097245080-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">1</span><span class="o">&gt;</span></code></pre><p>Failure: <code class="inline">badarg</code> if <code class="inline">String</code> contains a bad representation of a process
│ │ │  identifier.</p><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p>This BIF is intended for debugging and is not to be used in application
│ │ │  programs.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_port/1">
│ │ │  
│ │ │ @@ -10814,15 +10814,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_port(String) -> <a href="#t:port/0">port</a>() when String :: <a href="#t:string/0">string</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a port identifier whose text representation is a <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_port</span><span class="p" data-group-id="5834087335-1">(</span><span class="s">&quot;#Port&lt;0.4&gt;&quot;</span><span class="p" data-group-id="5834087335-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns a port identifier whose text representation is a <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_port</span><span class="p" data-group-id="7518753749-1">(</span><span class="s">&quot;#Port&lt;0.4&gt;&quot;</span><span class="p" data-group-id="7518753749-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Port</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="o">&gt;</span></code></pre><p>Failure: <code class="inline">badarg</code> if <code class="inline">String</code> contains a bad representation of a port
│ │ │  identifier.</p><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p>This BIF is intended for debugging and is not to be used in application
│ │ │  programs.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_ref/1">
│ │ │  
│ │ │ @@ -10847,15 +10847,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_ref(String) -> <a href="#t:reference/0">reference</a>() when String :: <a href="#t:string/0">string</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a reference whose text representation is a <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_ref</span><span class="p" data-group-id="8489827359-1">(</span><span class="s">&quot;#Ref&lt;0.4192537678.4073193475.71181&gt;&quot;</span><span class="p" data-group-id="8489827359-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns a reference whose text representation is a <code class="inline">String</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_ref</span><span class="p" data-group-id="2628377210-1">(</span><span class="s">&quot;#Ref&lt;0.4192537678.4073193475.71181&gt;&quot;</span><span class="p" data-group-id="2628377210-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="p">#</span><span class="n">Ref</span><span class="o">&lt;</span><span class="mf">0.4192537678</span><span class="p">.</span><span class="mf">4073193475.71181</span><span class="o">&gt;</span></code></pre><p>Failure: <code class="inline">badarg</code> if <code class="inline">String</code> contains a bad representation of a reference.</p><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p>This BIF is intended for debugging and is not to be used in application
│ │ │  programs.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="list_to_tuple/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -10877,16 +10877,16 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> list_to_tuple(List) -> <a href="#t:tuple/0">tuple</a>() when List :: [<a href="#t:term/0">term</a>()].</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a tuple corresponding to <code class="inline">List</code>, for example</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_tuple</span><span class="p" data-group-id="6075428591-1">(</span><span class="p" data-group-id="6075428591-2">[</span><span class="ss">share</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6075428591-3">[</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="w"> </span><span class="mi">163</span><span class="p" data-group-id="6075428591-3">]</span><span class="p" data-group-id="6075428591-2">]</span><span class="p" data-group-id="6075428591-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6075428591-4">{</span><span class="ss">share</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6075428591-5">[</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="w"> </span><span class="mi">163</span><span class="p" data-group-id="6075428591-5">]</span><span class="p" data-group-id="6075428591-4">}</span></code></pre><p><code class="inline">List</code> can contain any Erlang terms.</p>
│ │ │ +<p>Returns a tuple corresponding to <code class="inline">List</code>, for example</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">list_to_tuple</span><span class="p" data-group-id="5889379075-1">(</span><span class="p" data-group-id="5889379075-2">[</span><span class="ss">share</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5889379075-3">[</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="w"> </span><span class="mi">163</span><span class="p" data-group-id="5889379075-3">]</span><span class="p" data-group-id="5889379075-2">]</span><span class="p" data-group-id="5889379075-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5889379075-4">{</span><span class="ss">share</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5889379075-5">[</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="w"> </span><span class="mi">163</span><span class="p" data-group-id="5889379075-5">]</span><span class="p" data-group-id="5889379075-4">}</span></code></pre><p><code class="inline">List</code> can contain any Erlang terms.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="make_ref/0">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#make_ref/0" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -10936,16 +10936,16 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> make_tuple(Arity, InitialValue) -> <a href="#t:tuple/0">tuple</a>() when Arity :: <a href="#t:arity/0">arity</a>(), InitialValue :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Creates a new tuple of the specified <code class="inline">Arity</code>, where all elements are
│ │ │ -<code class="inline">InitialValue</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">make_tuple</span><span class="p" data-group-id="6000036745-1">(</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6000036745-2">[</span><span class="p" data-group-id="6000036745-2">]</span><span class="p" data-group-id="6000036745-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6000036745-3">{</span><span class="p" data-group-id="6000036745-4">[</span><span class="p" data-group-id="6000036745-4">]</span><span class="p">,</span><span class="p" data-group-id="6000036745-5">[</span><span class="p" data-group-id="6000036745-5">]</span><span class="p">,</span><span class="p" data-group-id="6000036745-6">[</span><span class="p" data-group-id="6000036745-6">]</span><span class="p">,</span><span class="p" data-group-id="6000036745-7">[</span><span class="p" data-group-id="6000036745-7">]</span><span class="p" data-group-id="6000036745-3">}</span></code></pre>
│ │ │ +<code class="inline">InitialValue</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">make_tuple</span><span class="p" data-group-id="2117878009-1">(</span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2117878009-2">[</span><span class="p" data-group-id="2117878009-2">]</span><span class="p" data-group-id="2117878009-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2117878009-3">{</span><span class="p" data-group-id="2117878009-4">[</span><span class="p" data-group-id="2117878009-4">]</span><span class="p">,</span><span class="p" data-group-id="2117878009-5">[</span><span class="p" data-group-id="2117878009-5">]</span><span class="p">,</span><span class="p" data-group-id="2117878009-6">[</span><span class="p" data-group-id="2117878009-6">]</span><span class="p">,</span><span class="p" data-group-id="2117878009-7">[</span><span class="p" data-group-id="2117878009-7">]</span><span class="p" data-group-id="2117878009-3">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="make_tuple/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#make_tuple/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -10971,16 +10971,16 @@
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Creates a tuple of size <code class="inline">Arity</code>, where each element has value <code class="inline">DefaultValue</code>,
│ │ │  and then fills in values from <code class="inline">InitList</code>.</p><p>Each list element in <code class="inline">InitList</code> must be a two-tuple, where the first element is
│ │ │  a position in the newly created tuple and the second element is any term. If a
│ │ │  position occurs more than once in the list, the term corresponding to the last
│ │ │ -occurrence is used.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">make_tuple</span><span class="p" data-group-id="1919076148-1">(</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1919076148-2">[</span><span class="p" data-group-id="1919076148-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1919076148-3">[</span><span class="p" data-group-id="1919076148-4">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">ignored</span><span class="p" data-group-id="1919076148-4">}</span><span class="p">,</span><span class="p" data-group-id="1919076148-5">{</span><span class="mi">5</span><span class="p">,</span><span class="ss">zz</span><span class="p" data-group-id="1919076148-5">}</span><span class="p">,</span><span class="p" data-group-id="1919076148-6">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">aa</span><span class="p" data-group-id="1919076148-6">}</span><span class="p" data-group-id="1919076148-3">]</span><span class="p" data-group-id="1919076148-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1919076148-7">{</span><span class="p" data-group-id="1919076148-8">[</span><span class="p" data-group-id="1919076148-8">]</span><span class="p">,</span><span class="ss">aa</span><span class="p">,</span><span class="p" data-group-id="1919076148-9">[</span><span class="p" data-group-id="1919076148-9">]</span><span class="p">,</span><span class="p" data-group-id="1919076148-10">[</span><span class="p" data-group-id="1919076148-10">]</span><span class="p">,</span><span class="ss">zz</span><span class="p" data-group-id="1919076148-7">}</span></code></pre>
│ │ │ +occurrence is used.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">make_tuple</span><span class="p" data-group-id="8986661969-1">(</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8986661969-2">[</span><span class="p" data-group-id="8986661969-2">]</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8986661969-3">[</span><span class="p" data-group-id="8986661969-4">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">ignored</span><span class="p" data-group-id="8986661969-4">}</span><span class="p">,</span><span class="p" data-group-id="8986661969-5">{</span><span class="mi">5</span><span class="p">,</span><span class="ss">zz</span><span class="p" data-group-id="8986661969-5">}</span><span class="p">,</span><span class="p" data-group-id="8986661969-6">{</span><span class="mi">2</span><span class="p">,</span><span class="ss">aa</span><span class="p" data-group-id="8986661969-6">}</span><span class="p" data-group-id="8986661969-3">]</span><span class="p" data-group-id="8986661969-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8986661969-7">{</span><span class="p" data-group-id="8986661969-8">[</span><span class="p" data-group-id="8986661969-8">]</span><span class="p">,</span><span class="ss">aa</span><span class="p">,</span><span class="p" data-group-id="8986661969-9">[</span><span class="p" data-group-id="8986661969-9">]</span><span class="p">,</span><span class="p" data-group-id="8986661969-10">[</span><span class="p" data-group-id="8986661969-10">]</span><span class="p">,</span><span class="ss">zz</span><span class="p" data-group-id="8986661969-7">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="map_get/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#map_get/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -11006,16 +11006,16 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> map_get(Key, Map) -> Value when Map :: <a href="#t:map/0">map</a>(), Key :: <a href="#t:any/0">any</a>(), Value :: <a href="#t:any/0">any</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns value <code class="inline">Value</code> associated with <code class="inline">Key</code> if <code class="inline">Map</code> contains <code class="inline">Key</code>.</p><p>The call fails with a <code class="inline">{badmap,Map}</code> exception if <code class="inline">Map</code> is not a map, or with a
│ │ │  <code class="inline">{badkey,Key}</code> exception if no value is associated with <code class="inline">Key</code>.</p><p><em>Example:</em></p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Key</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">1337</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5345578787-1">#{</span><span class="mi">42</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value_two</span><span class="p">,</span><span class="mi">1337</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;value one&quot;</span><span class="p">,</span><span class="s">&quot;a&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="5345578787-1">}</span><span class="p">,</span><span class="w">
│ │ │ -  </span><span class="nf">map_get</span><span class="p" data-group-id="5345578787-2">(</span><span class="n">Key</span><span class="p">,</span><span class="n">Map</span><span class="p" data-group-id="5345578787-2">)</span><span class="p">.</span><span class="w">
│ │ │ +  </span><span class="n">Map</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="5077727378-1">#{</span><span class="mi">42</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">value_two</span><span class="p">,</span><span class="mi">1337</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="s">&quot;value one&quot;</span><span class="p">,</span><span class="s">&quot;a&quot;</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="5077727378-1">}</span><span class="p">,</span><span class="w">
│ │ │ +  </span><span class="nf">map_get</span><span class="p" data-group-id="5077727378-2">(</span><span class="n">Key</span><span class="p">,</span><span class="n">Map</span><span class="p" data-group-id="5077727378-2">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;value one&quot;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="map_size/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#map_size/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -11040,15 +11040,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> map_size(Map) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Map :: <a href="#t:map/0">map</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer, which is the number of key-value pairs in <code class="inline">Map</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="3287806492-1">(</span><span class="p" data-group-id="3287806492-2">#{</span><span class="ss">a</span><span class="p">=&gt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">=&gt;</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p">=&gt;</span><span class="mi">3</span><span class="p" data-group-id="3287806492-2">}</span><span class="p" data-group-id="3287806492-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer, which is the number of key-value pairs in <code class="inline">Map</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">map_size</span><span class="p" data-group-id="1922248427-1">(</span><span class="p" data-group-id="1922248427-2">#{</span><span class="ss">a</span><span class="p">=&gt;</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">=&gt;</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p">=&gt;</span><span class="mi">3</span><span class="p" data-group-id="1922248427-2">}</span><span class="p" data-group-id="1922248427-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="match_spec_test/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#match_spec_test/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -11119,18 +11119,18 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> max(Term1, Term2) -> Maximum when Term1 :: <a href="#t:term/0">term</a>(), Term2 :: <a href="#t:term/0">term</a>(), Maximum :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the largest of <code class="inline">Term1</code> and <code class="inline">Term2</code>. If the terms compare equal with the
│ │ │  <code class="inline">==</code> operator, <code class="inline">Term1</code> is returned.</p><p>The <a href="../../../doc/system/expressions.html#term-comparisons">Expressions section</a> contains
│ │ │ -descriptions of the <code class="inline">==</code> operator and how terms are ordered.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="3373883494-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="3373883494-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">2</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="0758014013-1">(</span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="0758014013-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mf">1.0</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="7156432196-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="7156432196-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="1705100604-1">(</span><span class="s">&quot;abc&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;b&quot;</span><span class="p" data-group-id="1705100604-1">)</span><span class="p">.</span><span class="w">
│ │ │ +descriptions of the <code class="inline">==</code> operator and how terms are ordered.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="0563708741-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="0563708741-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">2</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="5904579057-1">(</span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="5904579057-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mf">1.0</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="0325182607-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="0325182607-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">max</span><span class="p" data-group-id="5601900627-1">(</span><span class="s">&quot;abc&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;b&quot;</span><span class="p" data-group-id="5601900627-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;b&quot;</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Allowed in guards tests from Erlang/OTP 26.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="min/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#min/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -11155,18 +11155,18 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> min(Term1, Term2) -> Minimum when Term1 :: <a href="#t:term/0">term</a>(), Term2 :: <a href="#t:term/0">term</a>(), Minimum :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the smallest of <code class="inline">Term1</code> and <code class="inline">Term2</code>. If the terms compare equal with the
│ │ │  <code class="inline">==</code> operator, <code class="inline">Term1</code> is returned.</p><p>The <a href="../../../doc/system/expressions.html#term-comparisons">Expressions section</a> contains
│ │ │ -descriptions of the <code class="inline">==</code> operator and how terms are ordered.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="7720264007-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="7720264007-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="5301017134-1">(</span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="5301017134-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mf">1.0</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="0233750873-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="0233750873-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="1097749060-1">(</span><span class="s">&quot;abc&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;b&quot;</span><span class="p" data-group-id="1097749060-1">)</span><span class="p">.</span><span class="w">
│ │ │ +descriptions of the <code class="inline">==</code> operator and how terms are ordered.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="9551694196-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="9551694196-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="4595631610-1">(</span><span class="mf">1.0</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p" data-group-id="4595631610-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mf">1.0</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="5211096342-1">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mf">1.0</span><span class="p" data-group-id="5211096342-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">1</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">min</span><span class="p" data-group-id="7918731166-1">(</span><span class="s">&quot;abc&quot;</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;b&quot;</span><span class="p" data-group-id="7918731166-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;abc&quot;</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Allowed in guards tests from Erlang/OTP 26.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="node/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#node/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -11276,15 +11276,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> pid_to_list(Pid) -> <a href="#t:string/0">string</a>() when Pid :: <a href="#t:pid/0">pid</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a string corresponding to the text representation of <code class="inline">Pid</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">pid_to_list</span><span class="p" data-group-id="0278366948-1">(</span><span class="nf">self</span><span class="p" data-group-id="0278366948-2">(</span><span class="p" data-group-id="0278366948-2">)</span><span class="p" data-group-id="0278366948-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns a string corresponding to the text representation of <code class="inline">Pid</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">pid_to_list</span><span class="p" data-group-id="0768646379-1">(</span><span class="nf">self</span><span class="p" data-group-id="0768646379-2">(</span><span class="p" data-group-id="0768646379-2">)</span><span class="p" data-group-id="0768646379-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;&lt;0.85.0&gt;&quot;</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The <a href="erl_dist_protocol.html">creation</a> for the node is not included in the list
│ │ │  representation of <code class="inline">Pid</code>. This means that processes in different incarnations
│ │ │  of a node with a specific name can get the same list representation.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="port_to_list/1">
│ │ │  
│ │ │ @@ -11367,18 +11367,18 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> round(Number) -> <a href="#t:integer/0">integer</a>() when Number :: <a href="#t:number/0">number</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer by rounding <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="5141285902-1">(</span><span class="mf">42.1</span><span class="p" data-group-id="5141285902-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">42</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="8533997665-1">(</span><span class="mf">5.5</span><span class="p" data-group-id="8533997665-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">6</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="8904450553-1">(</span><span class="o">-</span><span class="mf">5.5</span><span class="p" data-group-id="8904450553-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">-</span><span class="mi">6</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="9530800233-1">(</span><span class="mf">36028797018963969.0</span><span class="p" data-group-id="9530800233-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer by rounding <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="3055006490-1">(</span><span class="mf">42.1</span><span class="p" data-group-id="3055006490-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">42</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="1227880778-1">(</span><span class="mf">5.5</span><span class="p" data-group-id="1227880778-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">6</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="0776721430-1">(</span><span class="o">-</span><span class="mf">5.5</span><span class="p" data-group-id="0776721430-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">-</span><span class="mi">6</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="nf">round</span><span class="p" data-group-id="9161574996-1">(</span><span class="mf">36028797018963969.0</span><span class="p" data-group-id="9161574996-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">36028797018963968</span></code></pre><p>In the last example, <a href="#round/1"><code class="inline">round(36028797018963969.0)</code></a> evaluates to
│ │ │  <code class="inline">36028797018963968</code>. The reason for this is that the number
│ │ │  <code class="inline">36028797018963969.0</code> cannot be represented exactly as a float value. Instead,
│ │ │  the float literal is represented as <code class="inline">36028797018963968.0</code>, which is the closest
│ │ │  number that can be represented exactly as a float value. See
│ │ │  <a href="../../../doc/system/data_types.html#float_representation_problem">Representation of Floating Point Numbers</a>
│ │ │  for additional information.</p>
│ │ │ @@ -11408,16 +11408,16 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> setelement(Index, Tuple1, Value) -> Tuple2
│ │ │                      when Index :: <a href="#t:pos_integer/0">pos_integer</a>(), Tuple1 :: <a href="#t:tuple/0">tuple</a>(), Tuple2 :: <a href="#t:tuple/0">tuple</a>(), Value :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a tuple that is a copy of argument <code class="inline">Tuple1</code> with the element specified
│ │ │  by integer argument <code class="inline">Index</code> (the first element is the element with index 1)
│ │ │ -replaced by argument <code class="inline">Value</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">setelement</span><span class="p" data-group-id="9400157638-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9400157638-2">{</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="p">,</span><span class="w"> </span><span class="ss">bottles</span><span class="p" data-group-id="9400157638-2">}</span><span class="p">,</span><span class="w"> </span><span class="ss">red</span><span class="p" data-group-id="9400157638-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9400157638-3">{</span><span class="mi">10</span><span class="p">,</span><span class="ss">red</span><span class="p">,</span><span class="ss">bottles</span><span class="p" data-group-id="9400157638-3">}</span></code></pre>
│ │ │ +replaced by argument <code class="inline">Value</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">setelement</span><span class="p" data-group-id="2569213935-1">(</span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2569213935-2">{</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="ss">green</span><span class="p">,</span><span class="w"> </span><span class="ss">bottles</span><span class="p" data-group-id="2569213935-2">}</span><span class="p">,</span><span class="w"> </span><span class="ss">red</span><span class="p" data-group-id="2569213935-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2569213935-3">{</span><span class="mi">10</span><span class="p">,</span><span class="ss">red</span><span class="p">,</span><span class="ss">bottles</span><span class="p" data-group-id="2569213935-3">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="size/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#size/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -11440,17 +11440,17 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> size(Item) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Item :: <a href="#t:tuple/0">tuple</a>() | <a href="#t:binary/0">binary</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the number of elements in a tuple or the number of bytes in a binary or
│ │ │ -bitstring.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">size</span><span class="p" data-group-id="1466426710-1">(</span><span class="p" data-group-id="1466426710-2">{</span><span class="ss">morni</span><span class="p">,</span><span class="w"> </span><span class="ss">mulle</span><span class="p">,</span><span class="w"> </span><span class="ss">bwange</span><span class="p" data-group-id="1466426710-2">}</span><span class="p" data-group-id="1466426710-1">)</span><span class="p">.</span><span class="w">
│ │ │ +bitstring.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">size</span><span class="p" data-group-id="1720437697-1">(</span><span class="p" data-group-id="1720437697-2">{</span><span class="ss">morni</span><span class="p">,</span><span class="w"> </span><span class="ss">mulle</span><span class="p">,</span><span class="w"> </span><span class="ss">bwange</span><span class="p" data-group-id="1720437697-2">}</span><span class="p" data-group-id="1720437697-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">size</span><span class="p" data-group-id="1466426710-3">(</span><span class="p" data-group-id="1466426710-4">&lt;&lt;</span><span class="mi">11</span><span class="p">,</span><span class="w"> </span><span class="mi">22</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="1466426710-4">&gt;&gt;</span><span class="p" data-group-id="1466426710-3">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">size</span><span class="p" data-group-id="1720437697-3">(</span><span class="p" data-group-id="1720437697-4">&lt;&lt;</span><span class="mi">11</span><span class="p">,</span><span class="w"> </span><span class="mi">22</span><span class="p">,</span><span class="w"> </span><span class="mi">33</span><span class="p" data-group-id="1720437697-4">&gt;&gt;</span><span class="p" data-group-id="1720437697-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span></code></pre><p>For bitstrings, the number of whole bytes is returned. That is, if the number of
│ │ │  bits in the bitstring is not divisible by 8, the resulting number of bytes is
│ │ │  rounded <em>down</em>.</p><p>See also <a href="#tuple_size/1"><code class="inline">tuple_size/1</code></a>, <a href="#byte_size/1"><code class="inline">byte_size/1</code></a>, and <a href="#bit_size/1"><code class="inline">bit_size/1</code></a>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="split_binary/2">
│ │ │  
│ │ │ @@ -11474,23 +11474,23 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> split_binary(Bin, Pos) -> {<a href="#t:binary/0">binary</a>(), <a href="#t:binary/0">binary</a>()} when Bin :: <a href="#t:binary/0">binary</a>(), Pos :: <a href="#t:non_neg_integer/0">non_neg_integer</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a tuple containing the binaries that are the result of splitting <code class="inline">Bin</code>
│ │ │ -into two parts at position <code class="inline">Pos</code>.</p><p>This is not a destructive operation. After the operation, there are three binaries altogether.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">B</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">list_to_binary</span><span class="p" data-group-id="6709197224-1">(</span><span class="s">&quot;0123456789&quot;</span><span class="p" data-group-id="6709197224-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6709197224-2">&lt;&lt;</span><span class="s">&quot;0123456789&quot;</span><span class="p" data-group-id="6709197224-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="6709197224-3">(</span><span class="n">B</span><span class="p" data-group-id="6709197224-3">)</span><span class="p">.</span><span class="w">
│ │ │ +into two parts at position <code class="inline">Pos</code>.</p><p>This is not a destructive operation. After the operation, there are three binaries altogether.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">B</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">list_to_binary</span><span class="p" data-group-id="0421081621-1">(</span><span class="s">&quot;0123456789&quot;</span><span class="p" data-group-id="0421081621-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0421081621-2">&lt;&lt;</span><span class="s">&quot;0123456789&quot;</span><span class="p" data-group-id="0421081621-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="0421081621-3">(</span><span class="n">B</span><span class="p" data-group-id="0421081621-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">10</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="p" data-group-id="6709197224-4">{</span><span class="n">B1</span><span class="p">,</span><span class="w"> </span><span class="n">B2</span><span class="p" data-group-id="6709197224-4">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">split_binary</span><span class="p" data-group-id="6709197224-5">(</span><span class="n">B</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="6709197224-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6709197224-6">{</span><span class="p" data-group-id="6709197224-7">&lt;&lt;</span><span class="s">&quot;012&quot;</span><span class="p" data-group-id="6709197224-7">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="6709197224-8">&lt;&lt;</span><span class="s">&quot;3456789&quot;</span><span class="p" data-group-id="6709197224-8">&gt;&gt;</span><span class="p" data-group-id="6709197224-6">}</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="6709197224-9">(</span><span class="n">B1</span><span class="p" data-group-id="6709197224-9">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="p" data-group-id="0421081621-4">{</span><span class="n">B1</span><span class="p">,</span><span class="w"> </span><span class="n">B2</span><span class="p" data-group-id="0421081621-4">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">split_binary</span><span class="p" data-group-id="0421081621-5">(</span><span class="n">B</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="0421081621-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="0421081621-6">{</span><span class="p" data-group-id="0421081621-7">&lt;&lt;</span><span class="s">&quot;012&quot;</span><span class="p" data-group-id="0421081621-7">&gt;&gt;</span><span class="p">,</span><span class="p" data-group-id="0421081621-8">&lt;&lt;</span><span class="s">&quot;3456789&quot;</span><span class="p" data-group-id="0421081621-8">&gt;&gt;</span><span class="p" data-group-id="0421081621-6">}</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="0421081621-9">(</span><span class="n">B1</span><span class="p" data-group-id="0421081621-9">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="6709197224-10">(</span><span class="n">B2</span><span class="p" data-group-id="6709197224-10">)</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="nf">byte_size</span><span class="p" data-group-id="0421081621-10">(</span><span class="n">B2</span><span class="p" data-group-id="0421081621-10">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">7</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="term_to_binary/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#term_to_binary/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -11514,17 +11514,17 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> term_to_binary(Term) -> <a href="#t:ext_binary/0">ext_binary</a>() when Term :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a binary data object that is the result of encoding <code class="inline">Term</code> according to
│ │ │  the <a href="erl_ext_dist.html">Erlang external term format.</a></p><p>This can be used for various purposes, for example, writing a term to a file in
│ │ │  an efficient way, or sending an Erlang term to some type of communications
│ │ │ -channel not supported by distributed Erlang.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="8718193981-1">(</span><span class="ss">hello</span><span class="p" data-group-id="8718193981-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8718193981-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="8718193981-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="ss">hello</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="8718193981-3">(</span><span class="n">Bin</span><span class="p" data-group-id="8718193981-3">)</span><span class="p">.</span><span class="w">
│ │ │ +channel not supported by distributed Erlang.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Bin</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">term_to_binary</span><span class="p" data-group-id="5827276069-1">(</span><span class="ss">hello</span><span class="p" data-group-id="5827276069-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5827276069-2">&lt;&lt;</span><span class="mi">131</span><span class="p">,</span><span class="mi">100</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">104</span><span class="p">,</span><span class="mi">101</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">108</span><span class="p">,</span><span class="mi">111</span><span class="p" data-group-id="5827276069-2">&gt;&gt;</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="ss">hello</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">binary_to_term</span><span class="p" data-group-id="5827276069-3">(</span><span class="n">Bin</span><span class="p" data-group-id="5827276069-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">hello</span></code></pre><p>See also <a href="#binary_to_term/1"><code class="inline">binary_to_term/1</code></a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>There is no guarantee that this function will return the same encoded
│ │ │  representation for the same term.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="term_to_binary/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -11741,18 +11741,18 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> tl(List) -> Tail when List :: <a href="#t:nonempty_maybe_improper_list/0">nonempty_maybe_improper_list</a>(), Tail :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the tail of <code class="inline">List</code>, that is, the list minus the first element</p><p>It works with improper lists.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="6457745526-1">(</span><span class="p" data-group-id="6457745526-2">[</span><span class="ss">geesties</span><span class="p">,</span><span class="w"> </span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="p" data-group-id="6457745526-2">]</span><span class="p" data-group-id="6457745526-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6457745526-3">[</span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="p" data-group-id="6457745526-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="9052432379-1">(</span><span class="p" data-group-id="9052432379-2">[</span><span class="ss">geesties</span><span class="p" data-group-id="9052432379-2">]</span><span class="p" data-group-id="9052432379-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9052432379-3">[</span><span class="p" data-group-id="9052432379-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="1633996340-1">(</span><span class="p" data-group-id="1633996340-2">[</span><span class="ss">geesties</span><span class="p">,</span><span class="w"> </span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="1633996340-2">]</span><span class="p" data-group-id="1633996340-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1633996340-3">[</span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="1633996340-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="4815095324-1">(</span><span class="p" data-group-id="4815095324-2">[</span><span class="ss">geesties</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="4815095324-2">]</span><span class="p" data-group-id="4815095324-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the tail of <code class="inline">List</code>, that is, the list minus the first element</p><p>It works with improper lists.</p><p>Examples:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="8839186941-1">(</span><span class="p" data-group-id="8839186941-2">[</span><span class="ss">geesties</span><span class="p">,</span><span class="w"> </span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="p" data-group-id="8839186941-2">]</span><span class="p" data-group-id="8839186941-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8839186941-3">[</span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="p" data-group-id="8839186941-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="2486903969-1">(</span><span class="p" data-group-id="2486903969-2">[</span><span class="ss">geesties</span><span class="p" data-group-id="2486903969-2">]</span><span class="p" data-group-id="2486903969-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2486903969-3">[</span><span class="p" data-group-id="2486903969-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="1276993790-1">(</span><span class="p" data-group-id="1276993790-2">[</span><span class="ss">geesties</span><span class="p">,</span><span class="w"> </span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="1276993790-2">]</span><span class="p" data-group-id="1276993790-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1276993790-3">[</span><span class="ss">guilies</span><span class="p">,</span><span class="w"> </span><span class="ss">beasties</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="1276993790-3">]</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tl</span><span class="p" data-group-id="6383521444-1">(</span><span class="p" data-group-id="6383521444-2">[</span><span class="ss">geesties</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="ss">improper_end</span><span class="p" data-group-id="6383521444-2">]</span><span class="p" data-group-id="6383521444-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">improper_end</span></code></pre><p>Failure: <code class="inline">badarg</code> if <code class="inline">List</code> is an empty list <code class="inline">[]</code>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="trunc/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#trunc/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -11775,18 +11775,18 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> trunc(Number) -> <a href="#t:integer/0">integer</a>() when Number :: <a href="#t:number/0">number</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Truncates the decimals of <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="0730632574-1">(</span><span class="mf">5.7</span><span class="p" data-group-id="0730632574-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">5</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="5245383080-1">(</span><span class="o">-</span><span class="mf">5.7</span><span class="p" data-group-id="5245383080-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="o">-</span><span class="mi">5</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="8427686583-1">(</span><span class="mi">5</span><span class="p" data-group-id="8427686583-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="mi">5</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="0066028051-1">(</span><span class="mf">36028797018963969.0</span><span class="p" data-group-id="0066028051-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Truncates the decimals of <code class="inline">Number</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="4019931788-1">(</span><span class="mf">5.7</span><span class="p" data-group-id="4019931788-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">5</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="7369509139-1">(</span><span class="o">-</span><span class="mf">5.7</span><span class="p" data-group-id="7369509139-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="o">-</span><span class="mi">5</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="8003959903-1">(</span><span class="mi">5</span><span class="p" data-group-id="8003959903-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="mi">5</span></code></pre><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">trunc</span><span class="p" data-group-id="8561863215-1">(</span><span class="mf">36028797018963969.0</span><span class="p" data-group-id="8561863215-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">36028797018963968</span></code></pre><p>In the last example, <a href="#trunc/1"><code class="inline">trunc(36028797018963969.0)</code></a> evaluates to
│ │ │  <code class="inline">36028797018963968</code>. The reason for this is that the number
│ │ │  <code class="inline">36028797018963969.0</code> cannot be represented exactly as a float value. Instead,
│ │ │  the float literal is represented as <code class="inline">36028797018963968.0</code>, which is the closest
│ │ │  number that can be represented exactly as a float value. See
│ │ │  <a href="../../../doc/system/data_types.html#float_representation_problem">Representation of Floating Point Numbers</a>
│ │ │  for additional information.</p>
│ │ │ @@ -11815,15 +11815,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> tuple_size(Tuple) -> <a href="#t:non_neg_integer/0">non_neg_integer</a>() when Tuple :: <a href="#t:tuple/0">tuple</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns an integer that is the number of elements in <code class="inline">Tuple</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="0137036703-1">(</span><span class="p" data-group-id="0137036703-2">{</span><span class="ss">morni</span><span class="p">,</span><span class="w"> </span><span class="ss">mulle</span><span class="p">,</span><span class="w"> </span><span class="ss">bwange</span><span class="p" data-group-id="0137036703-2">}</span><span class="p" data-group-id="0137036703-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns an integer that is the number of elements in <code class="inline">Tuple</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tuple_size</span><span class="p" data-group-id="5206636291-1">(</span><span class="p" data-group-id="5206636291-2">{</span><span class="ss">morni</span><span class="p">,</span><span class="w"> </span><span class="ss">mulle</span><span class="p">,</span><span class="w"> </span><span class="ss">bwange</span><span class="p" data-group-id="5206636291-2">}</span><span class="p" data-group-id="5206636291-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mi">3</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="tuple_to_list/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#tuple_to_list/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -11845,16 +11845,16 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> tuple_to_list(Tuple) -> [<a href="#t:term/0">term</a>()] when Tuple :: <a href="#t:tuple/0">tuple</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a list corresponding to <code class="inline">Tuple</code>. <code class="inline">Tuple</code> can contain any Erlang terms.
│ │ │ -Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tuple_to_list</span><span class="p" data-group-id="1606360975-1">(</span><span class="p" data-group-id="1606360975-2">{</span><span class="ss">share</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1606360975-3">{</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="w"> </span><span class="mi">163</span><span class="p" data-group-id="1606360975-3">}</span><span class="p" data-group-id="1606360975-2">}</span><span class="p" data-group-id="1606360975-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="1606360975-4">[</span><span class="ss">share</span><span class="p">,</span><span class="p" data-group-id="1606360975-5">{</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="mi">163</span><span class="p" data-group-id="1606360975-5">}</span><span class="p" data-group-id="1606360975-4">]</span></code></pre>
│ │ │ +Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">tuple_to_list</span><span class="p" data-group-id="8626497215-1">(</span><span class="p" data-group-id="8626497215-2">{</span><span class="ss">share</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8626497215-3">{</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="w"> </span><span class="mi">163</span><span class="p" data-group-id="8626497215-3">}</span><span class="p" data-group-id="8626497215-2">}</span><span class="p" data-group-id="8626497215-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8626497215-4">[</span><span class="ss">share</span><span class="p">,</span><span class="p" data-group-id="8626497215-5">{</span><span class="ss">&#39;Ericsson_B&#39;</span><span class="p">,</span><span class="mi">163</span><span class="p" data-group-id="8626497215-5">}</span><span class="p" data-group-id="8626497215-4">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="unique_integer/0">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#unique_integer/0" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12009,35 +12009,35 @@
│ │ │  
│ │ │  <p>Create an alias which can be used when sending messages to the process that
│ │ │  created the alias. When the alias has been deactivated, messages sent using the
│ │ │  alias will be dropped. An alias can be deactivated using <a href="#unalias/1"><code class="inline">unalias/1</code></a>.</p><p>Currently available options for <a href="#alias/1"><code class="inline">alias/1</code></a>:</p><ul><li><p><strong><code class="inline">explicit_unalias</code></strong> - The alias can only be deactivated via a call to
│ │ │  <a href="#unalias/1"><code class="inline">unalias/1</code></a>. This is also the default behaviour if no options
│ │ │  are passed or if <a href="#alias/0"><code class="inline">alias/0</code></a> is called.</p></li><li><p><strong><code class="inline">reply</code></strong> - The alias will be automatically deactivated when a reply message
│ │ │  sent via the alias is received. The alias can also still be deactivated via a
│ │ │ -call to <a href="#unalias/1"><code class="inline">unalias/1</code></a>.</p></li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server</span><span class="p" data-group-id="0118413583-1">(</span><span class="p" data-group-id="0118413583-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +call to <a href="#unalias/1"><code class="inline">unalias/1</code></a>.</p></li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server</span><span class="p" data-group-id="7565651867-1">(</span><span class="p" data-group-id="7565651867-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0118413583-2">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="0118413583-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">perform_request</span><span class="p" data-group-id="0118413583-3">(</span><span class="n">Request</span><span class="p" data-group-id="0118413583-3">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">AliasReqId</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0118413583-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="0118413583-4">}</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="7565651867-2">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="7565651867-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">perform_request</span><span class="p" data-group-id="7565651867-3">(</span><span class="n">Request</span><span class="p" data-group-id="7565651867-3">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">AliasReqId</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7565651867-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7565651867-4">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">server</span><span class="p" data-group-id="0118413583-5">(</span><span class="p" data-group-id="0118413583-5">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">server</span><span class="p" data-group-id="7565651867-5">(</span><span class="p" data-group-id="7565651867-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="0118413583-6">(</span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="0118413583-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">AliasReqId</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alias</span><span class="p" data-group-id="0118413583-7">(</span><span class="p" data-group-id="0118413583-8">[</span><span class="ss">reply</span><span class="p" data-group-id="0118413583-8">]</span><span class="p" data-group-id="0118413583-7">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ServerPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="0118413583-9">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="0118413583-9">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="7565651867-6">(</span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="7565651867-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">AliasReqId</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">alias</span><span class="p" data-group-id="7565651867-7">(</span><span class="p" data-group-id="7565651867-8">[</span><span class="ss">reply</span><span class="p" data-group-id="7565651867-8">]</span><span class="p" data-group-id="7565651867-7">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ServerPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7565651867-9">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="7565651867-9">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="c1">%% Alias will be automatically deactivated if we receive a reply</span><span class="w">
│ │ │      </span><span class="c1">%% since we used the &#39;reply&#39; option...</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="0118413583-10">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="0118413583-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="7565651867-10">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7565651867-10">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="w">
│ │ │      </span><span class="k">after</span><span class="w"> </span><span class="mi">5000</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">unalias</span><span class="p" data-group-id="0118413583-11">(</span><span class="n">AliasReqId</span><span class="p" data-group-id="0118413583-11">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="nf">unalias</span><span class="p" data-group-id="7565651867-11">(</span><span class="n">AliasReqId</span><span class="p" data-group-id="7565651867-11">)</span><span class="p">,</span><span class="w">
│ │ │              </span><span class="c1">%% Flush message queue in case the reply arrived</span><span class="w">
│ │ │              </span><span class="c1">%% just before the alias was deactivated...</span><span class="w">
│ │ │ -            </span><span class="k">receive</span><span class="w"> </span><span class="p" data-group-id="0118413583-12">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="0118413583-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="w">
│ │ │ -            </span><span class="k">after</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="0118413583-13">(</span><span class="ss">timeout</span><span class="p" data-group-id="0118413583-13">)</span><span class="w">
│ │ │ +            </span><span class="k">receive</span><span class="w"> </span><span class="p" data-group-id="7565651867-12">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7565651867-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">Result</span><span class="w">
│ │ │ +            </span><span class="k">after</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="7565651867-13">(</span><span class="ss">timeout</span><span class="p" data-group-id="7565651867-13">)</span><span class="w">
│ │ │              </span><span class="k">end</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Note that both the server and the client in this example must be executing on at
│ │ │  least OTP 24 systems in order for this to work.</p><p>For more information on process aliases see the
│ │ │  <a href="../../../doc/system/ref_man_processes.html#process-aliases"><em>Process Aliases</em></a> section of
│ │ │  the <em>Erlang Reference Manual</em>.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │ @@ -12096,17 +12096,17 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> apply(Module, Function, Args) -> <a href="#t:term/0">term</a>()
│ │ │                 when Module :: <a href="#t:module/0">module</a>(), Function :: <a href="#t:atom/0">atom</a>(), Args :: [<a href="#t:term/0">term</a>()].</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the result of applying <code class="inline">Function</code> in <code class="inline">Module</code> to <code class="inline">Args</code>. The applied
│ │ │  function must be exported from <code class="inline">Module</code>. The arity of the function is the length
│ │ │ -of <code class="inline">Args</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">apply</span><span class="p" data-group-id="6787256278-1">(</span><span class="ss">lists</span><span class="p">,</span><span class="w"> </span><span class="ss">reverse</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787256278-2">[</span><span class="p" data-group-id="6787256278-3">[</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="6787256278-3">]</span><span class="p" data-group-id="6787256278-2">]</span><span class="p" data-group-id="6787256278-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6787256278-4">[</span><span class="ss">c</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="6787256278-4">]</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nf">apply</span><span class="p" data-group-id="6787256278-5">(</span><span class="ss">erlang</span><span class="p">,</span><span class="w"> </span><span class="nb">atom_to_list</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787256278-6">[</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="6787256278-6">]</span><span class="p" data-group-id="6787256278-5">)</span><span class="p">.</span><span class="w">
│ │ │ +of <code class="inline">Args</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">apply</span><span class="p" data-group-id="3066936093-1">(</span><span class="ss">lists</span><span class="p">,</span><span class="w"> </span><span class="ss">reverse</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3066936093-2">[</span><span class="p" data-group-id="3066936093-3">[</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="3066936093-3">]</span><span class="p" data-group-id="3066936093-2">]</span><span class="p" data-group-id="3066936093-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3066936093-4">[</span><span class="ss">c</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">a</span><span class="p" data-group-id="3066936093-4">]</span><span class="gp unselectable">
│ │ │ +&gt; </span><span class="nf">apply</span><span class="p" data-group-id="3066936093-5">(</span><span class="ss">erlang</span><span class="p">,</span><span class="w"> </span><span class="nb">atom_to_list</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3066936093-6">[</span><span class="ss">&#39;Erlang&#39;</span><span class="p" data-group-id="3066936093-6">]</span><span class="p" data-group-id="3066936093-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="s">&quot;Erlang&quot;</span></code></pre><p>If the number of arguments are known at compile time, the call is better written
│ │ │  as <code class="inline">Module:Function(Arg1, Arg2, ..., ArgN)</code>.</p><p>Failure: <a href="../../../lib/kernel-10.2.7.2/doc/html/error_handler.html#undefined_function/3"><code class="inline">error_handler:undefined_function/3</code></a> is called if the applied function
│ │ │  is not exported. The error handler can be redefined (see <a href="#process_flag/2"><code class="inline">process_flag/2</code></a>). If
│ │ │  <code class="inline">error_handler</code> is undefined, or if the user has redefined the default
│ │ │  <code class="inline">error_handler</code> so the replacement module is undefined, an error with reason
│ │ │  <code class="inline">undef</code> is generated.</p>
│ │ │    </section>
│ │ │ @@ -12213,17 +12213,17 @@
│ │ │                     when MonitorRef :: <a href="#t:reference/0">reference</a>(), OptionList :: [Option], Option :: flush | info.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>The returned value is <code class="inline">true</code> unless <code class="inline">info</code> is part of <code class="inline">OptionList</code>.</p><p><a href="#demonitor/2"><code class="inline">demonitor(MonitorRef, [])</code></a> is equivalent to
│ │ │  <a href="#demonitor/1"><code class="inline">demonitor(MonitorRef)</code></a>.</p><p><code class="inline">Option</code>s:</p><ul><li><p><strong><code class="inline">flush</code></strong> - Removes (one) <code class="inline">{_, MonitorRef, _, _, _}</code> message, if there is
│ │ │  one, from the caller message queue after monitoring has been stopped.</p><p>Calling <a href="#demonitor/2"><code class="inline">demonitor(MonitorRef, [flush])</code></a> is equivalent to the
│ │ │ -following, but more efficient:</p><pre><code class="makeup erlang" translate="no"><span class="nf">demonitor</span><span class="p" data-group-id="5371710998-1">(</span><span class="n">MonitorRef</span><span class="p" data-group-id="5371710998-1">)</span><span class="p">,</span><span class="w">
│ │ │ +following, but more efficient:</p><pre><code class="makeup erlang" translate="no"><span class="nf">demonitor</span><span class="p" data-group-id="1744463620-1">(</span><span class="n">MonitorRef</span><span class="p" data-group-id="1744463620-1">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="5371710998-2">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="5371710998-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="1744463620-2">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="1744463620-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w">
│ │ │  </span><span class="k">after</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre></li><li><p><strong><code class="inline">info</code></strong> - The returned value is one of the following:</p><ul><li><p><strong><code class="inline">true</code></strong> - The monitor was found and removed. In this case, no <code class="inline">'DOWN'</code>
│ │ │  message corresponding to this monitor has been delivered and will not be
│ │ │  delivered.</p></li><li><p><strong><code class="inline">false</code></strong> - The monitor was not found and could not be removed. This
│ │ │  probably because someone already has placed a <code class="inline">'DOWN'</code> message corresponding
│ │ │ @@ -12252,18 +12252,18 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> erase() -> [{Key, Val}] when Key :: <a href="#t:term/0">term</a>(), Val :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the process dictionary and deletes it.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="8937526289-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8937526289-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="8937526289-2">}</span><span class="p" data-group-id="8937526289-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="8937526289-3">(</span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8937526289-4">[</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="8937526289-4">]</span><span class="p" data-group-id="8937526289-3">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">erase</span><span class="p" data-group-id="8937526289-5">(</span><span class="p" data-group-id="8937526289-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8937526289-6">[</span><span class="p" data-group-id="8937526289-7">{</span><span class="ss">key1</span><span class="p">,</span><span class="p" data-group-id="8937526289-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="8937526289-8">}</span><span class="p" data-group-id="8937526289-7">}</span><span class="p">,</span><span class="p" data-group-id="8937526289-9">{</span><span class="ss">key2</span><span class="p">,</span><span class="p" data-group-id="8937526289-10">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="8937526289-10">]</span><span class="p" data-group-id="8937526289-9">}</span><span class="p" data-group-id="8937526289-6">]</span></code></pre>
│ │ │ +<p>Returns the process dictionary and deletes it.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="3101916426-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3101916426-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="3101916426-2">}</span><span class="p" data-group-id="3101916426-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="3101916426-3">(</span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3101916426-4">[</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="ss">b</span><span class="p">,</span><span class="w"> </span><span class="ss">c</span><span class="p" data-group-id="3101916426-4">]</span><span class="p" data-group-id="3101916426-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">erase</span><span class="p" data-group-id="3101916426-5">(</span><span class="p" data-group-id="3101916426-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3101916426-6">[</span><span class="p" data-group-id="3101916426-7">{</span><span class="ss">key1</span><span class="p">,</span><span class="p" data-group-id="3101916426-8">{</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="3101916426-8">}</span><span class="p" data-group-id="3101916426-7">}</span><span class="p">,</span><span class="p" data-group-id="3101916426-9">{</span><span class="ss">key2</span><span class="p">,</span><span class="p" data-group-id="3101916426-10">[</span><span class="ss">a</span><span class="p">,</span><span class="ss">b</span><span class="p">,</span><span class="ss">c</span><span class="p" data-group-id="3101916426-10">]</span><span class="p" data-group-id="3101916426-9">}</span><span class="p" data-group-id="3101916426-6">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="erase/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#erase/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12286,18 +12286,18 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> erase(Key) -> Val | undefined when Key :: <a href="#t:term/0">term</a>(), Val :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the value <code class="inline">Val</code> associated with <code class="inline">Key</code> and deletes it from the process
│ │ │  dictionary. Returns <code class="inline">undefined</code> if no value is associated with <code class="inline">Key</code>.</p><p>The average time complexity for the current implementation of this function is
│ │ │  O(<code class="inline">1</code>) and the worst case time complexity is O(<code class="inline">N</code>), where <code class="inline">N</code> is the number of
│ │ │ -items in the process dictionary.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="4797685383-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4797685383-2">{</span><span class="ss">merry</span><span class="p">,</span><span class="w"> </span><span class="ss">lambs</span><span class="p">,</span><span class="w"> </span><span class="ss">are</span><span class="p">,</span><span class="w"> </span><span class="ss">playing</span><span class="p" data-group-id="4797685383-2">}</span><span class="p" data-group-id="4797685383-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erase</span><span class="p" data-group-id="4797685383-3">(</span><span class="ss">key1</span><span class="p" data-group-id="4797685383-3">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4797685383-4">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="nf">erase</span><span class="p" data-group-id="4797685383-5">(</span><span class="ss">key1</span><span class="p" data-group-id="4797685383-5">)</span><span class="p" data-group-id="4797685383-4">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4797685383-6">{</span><span class="p" data-group-id="4797685383-7">{</span><span class="ss">merry</span><span class="p">,</span><span class="ss">lambs</span><span class="p">,</span><span class="ss">are</span><span class="p">,</span><span class="ss">playing</span><span class="p" data-group-id="4797685383-7">}</span><span class="p">,</span><span class="ss">undefined</span><span class="p" data-group-id="4797685383-6">}</span></code></pre>
│ │ │ +items in the process dictionary.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="1294602927-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1294602927-2">{</span><span class="ss">merry</span><span class="p">,</span><span class="w"> </span><span class="ss">lambs</span><span class="p">,</span><span class="w"> </span><span class="ss">are</span><span class="p">,</span><span class="w"> </span><span class="ss">playing</span><span class="p" data-group-id="1294602927-2">}</span><span class="p" data-group-id="1294602927-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">erase</span><span class="p" data-group-id="1294602927-3">(</span><span class="ss">key1</span><span class="p" data-group-id="1294602927-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1294602927-4">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="nf">erase</span><span class="p" data-group-id="1294602927-5">(</span><span class="ss">key1</span><span class="p" data-group-id="1294602927-5">)</span><span class="p" data-group-id="1294602927-4">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1294602927-6">{</span><span class="p" data-group-id="1294602927-7">{</span><span class="ss">merry</span><span class="p">,</span><span class="ss">lambs</span><span class="p">,</span><span class="ss">are</span><span class="p">,</span><span class="ss">playing</span><span class="p" data-group-id="1294602927-7">}</span><span class="p">,</span><span class="ss">undefined</span><span class="p" data-group-id="1294602927-6">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="error/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#error/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12321,22 +12321,22 @@
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Raises an exception of class <code class="inline">error</code> with the reason <code class="inline">Reason</code>.</p><p>As evaluating this function causes an exception to be thrown, it has no return value.</p><p>The intent of the exception class <code class="inline">error</code> is to signal that an unexpected error
│ │ │  has happened (for example, a function is called with a parameter that has an
│ │ │  incorrect type). See the guide about
│ │ │  <a href="../../../doc/system/errors.html">errors and error handling</a> for additional information.
│ │ │ -Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">error</span><span class="p" data-group-id="0749510811-1">(</span><span class="ss">foobar</span><span class="p" data-group-id="0749510811-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0749510811-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="0749510811-3">{</span><span class="ss">foobar</span><span class="p">,</span><span class="p" data-group-id="0749510811-4">[</span><span class="p" data-group-id="0749510811-5">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ -                        </span><span class="p" data-group-id="0749510811-6">[</span><span class="p" data-group-id="0749510811-7">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="0749510811-7">}</span><span class="p">,</span><span class="p" data-group-id="0749510811-8">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">906</span><span class="p" data-group-id="0749510811-8">}</span><span class="p" data-group-id="0749510811-6">]</span><span class="p" data-group-id="0749510811-5">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="0749510811-9">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="0749510811-10">[</span><span class="p" data-group-id="0749510811-11">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="0749510811-11">}</span><span class="p">,</span><span class="p" data-group-id="0749510811-12">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">677</span><span class="p" data-group-id="0749510811-12">}</span><span class="p" data-group-id="0749510811-10">]</span><span class="p" data-group-id="0749510811-9">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="0749510811-13">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">expr</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="p" data-group-id="0749510811-14">[</span><span class="p" data-group-id="0749510811-15">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="0749510811-15">}</span><span class="p">,</span><span class="p" data-group-id="0749510811-16">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">430</span><span class="p" data-group-id="0749510811-16">}</span><span class="p" data-group-id="0749510811-14">]</span><span class="p" data-group-id="0749510811-13">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="0749510811-17">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="0749510811-18">[</span><span class="p" data-group-id="0749510811-19">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="0749510811-19">}</span><span class="p">,</span><span class="p" data-group-id="0749510811-20">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">687</span><span class="p" data-group-id="0749510811-20">}</span><span class="p" data-group-id="0749510811-18">]</span><span class="p" data-group-id="0749510811-17">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="0749510811-21">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="0749510811-22">[</span><span class="p" data-group-id="0749510811-23">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="0749510811-23">}</span><span class="p">,</span><span class="p" data-group-id="0749510811-24">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">642</span><span class="p" data-group-id="0749510811-24">}</span><span class="p" data-group-id="0749510811-22">]</span><span class="p" data-group-id="0749510811-21">}</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="p" data-group-id="0749510811-25">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_loop</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="0749510811-26">[</span><span class="p" data-group-id="0749510811-27">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="0749510811-27">}</span><span class="p">,</span><span class="p" data-group-id="0749510811-28">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">627</span><span class="p" data-group-id="0749510811-28">}</span><span class="p" data-group-id="0749510811-26">]</span><span class="p" data-group-id="0749510811-25">}</span><span class="p" data-group-id="0749510811-4">]</span><span class="p" data-group-id="0749510811-3">}</span><span class="p" data-group-id="0749510811-2">}</span></code></pre>
│ │ │ +Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">error</span><span class="p" data-group-id="4331987587-1">(</span><span class="ss">foobar</span><span class="p" data-group-id="4331987587-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="4331987587-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="p" data-group-id="4331987587-3">{</span><span class="ss">foobar</span><span class="p">,</span><span class="p" data-group-id="4331987587-4">[</span><span class="p" data-group-id="4331987587-5">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">apply_fun</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="w">
│ │ │ +                        </span><span class="p" data-group-id="4331987587-6">[</span><span class="p" data-group-id="4331987587-7">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="4331987587-7">}</span><span class="p">,</span><span class="p" data-group-id="4331987587-8">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">906</span><span class="p" data-group-id="4331987587-8">}</span><span class="p" data-group-id="4331987587-6">]</span><span class="p" data-group-id="4331987587-5">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="4331987587-9">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">do_apply</span><span class="p">,</span><span class="mi">6</span><span class="p">,</span><span class="p" data-group-id="4331987587-10">[</span><span class="p" data-group-id="4331987587-11">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="4331987587-11">}</span><span class="p">,</span><span class="p" data-group-id="4331987587-12">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">677</span><span class="p" data-group-id="4331987587-12">}</span><span class="p" data-group-id="4331987587-10">]</span><span class="p" data-group-id="4331987587-9">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="4331987587-13">{</span><span class="ss">erl_eval</span><span class="p">,</span><span class="ss">expr</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="p" data-group-id="4331987587-14">[</span><span class="p" data-group-id="4331987587-15">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;erl_eval.erl&quot;</span><span class="p" data-group-id="4331987587-15">}</span><span class="p">,</span><span class="p" data-group-id="4331987587-16">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">430</span><span class="p" data-group-id="4331987587-16">}</span><span class="p" data-group-id="4331987587-14">]</span><span class="p" data-group-id="4331987587-13">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="4331987587-17">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="4331987587-18">[</span><span class="p" data-group-id="4331987587-19">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="4331987587-19">}</span><span class="p">,</span><span class="p" data-group-id="4331987587-20">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">687</span><span class="p" data-group-id="4331987587-20">}</span><span class="p" data-group-id="4331987587-18">]</span><span class="p" data-group-id="4331987587-17">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="4331987587-21">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_exprs</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="p" data-group-id="4331987587-22">[</span><span class="p" data-group-id="4331987587-23">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="4331987587-23">}</span><span class="p">,</span><span class="p" data-group-id="4331987587-24">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">642</span><span class="p" data-group-id="4331987587-24">}</span><span class="p" data-group-id="4331987587-22">]</span><span class="p" data-group-id="4331987587-21">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="p" data-group-id="4331987587-25">{</span><span class="ss">shell</span><span class="p">,</span><span class="ss">eval_loop</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span><span class="p" data-group-id="4331987587-26">[</span><span class="p" data-group-id="4331987587-27">{</span><span class="ss">file</span><span class="p">,</span><span class="s">&quot;shell.erl&quot;</span><span class="p" data-group-id="4331987587-27">}</span><span class="p">,</span><span class="p" data-group-id="4331987587-28">{</span><span class="ss">line</span><span class="p">,</span><span class="mi">627</span><span class="p" data-group-id="4331987587-28">}</span><span class="p" data-group-id="4331987587-26">]</span><span class="p" data-group-id="4331987587-25">}</span><span class="p" data-group-id="4331987587-4">]</span><span class="p" data-group-id="4331987587-3">}</span><span class="p" data-group-id="4331987587-2">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="error/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#error/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12365,21 +12365,21 @@
│ │ │  <code class="inline">none</code>.</p><p>If <code class="inline">Args</code> is a list, it is used to provide the arguments for the current
│ │ │  function in the stack back-trace. If it is <code class="inline">none</code>, the arity of the calling
│ │ │  function is used in the stacktrace. As evaluating this function causes an
│ │ │  exception to be raised, it has no return value.</p><p>The intent of the exception class <code class="inline">error</code> is to signal that an unexpected error
│ │ │  has happened (for example, a function is called with a parameter that has an
│ │ │  incorrect type). See the guide about
│ │ │  <a href="../../../doc/system/errors.html">errors and error handling</a> for additional information.
│ │ │ -Example:</p><p><code class="inline">test.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="6176328802-1">(</span><span class="ss">test</span><span class="p" data-group-id="6176328802-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="6176328802-2">(</span><span class="p" data-group-id="6176328802-3">[</span><span class="ss">example_fun</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="6176328802-3">]</span><span class="p" data-group-id="6176328802-2">)</span><span class="p">.</span><span class="w">
│ │ │ +Example:</p><p><code class="inline">test.erl</code>:</p><pre><code class="makeup erlang" translate="no"><span class="p">-</span><span class="na">module</span><span class="p" data-group-id="9339342144-1">(</span><span class="ss">test</span><span class="p" data-group-id="9339342144-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p">-</span><span class="na">export</span><span class="p" data-group-id="9339342144-2">(</span><span class="p" data-group-id="9339342144-3">[</span><span class="ss">example_fun</span><span class="p">/</span><span class="mi">2</span><span class="p" data-group-id="9339342144-3">]</span><span class="p" data-group-id="9339342144-2">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">example_fun</span><span class="p" data-group-id="6176328802-4">(</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">A2</span><span class="p" data-group-id="6176328802-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">error</span><span class="p" data-group-id="6176328802-5">(</span><span class="ss">my_error</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6176328802-6">[</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">A2</span><span class="p" data-group-id="6176328802-6">]</span><span class="p" data-group-id="6176328802-5">)</span><span class="p">.</span></code></pre><p>Erlang shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">6&gt; </span><span class="nf">c</span><span class="p" data-group-id="2394263088-1">(</span><span class="ss">test</span><span class="p" data-group-id="2394263088-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2394263088-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">test</span><span class="p" data-group-id="2394263088-2">}</span><span class="gp unselectable">
│ │ │ -7&gt; </span><span class="nc">test</span><span class="p">:</span><span class="nf">example_fun</span><span class="p" data-group-id="2394263088-3">(</span><span class="ss">arg1</span><span class="p">,</span><span class="s">&quot;this is the second argument&quot;</span><span class="p" data-group-id="2394263088-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="nf">example_fun</span><span class="p" data-group-id="9339342144-4">(</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">A2</span><span class="p" data-group-id="9339342144-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">error</span><span class="p" data-group-id="9339342144-5">(</span><span class="ss">my_error</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="9339342144-6">[</span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">A2</span><span class="p" data-group-id="9339342144-6">]</span><span class="p" data-group-id="9339342144-5">)</span><span class="p">.</span></code></pre><p>Erlang shell:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">6&gt; </span><span class="nf">c</span><span class="p" data-group-id="3635353046-1">(</span><span class="ss">test</span><span class="p" data-group-id="3635353046-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3635353046-2">{</span><span class="ss">ok</span><span class="p">,</span><span class="ss">test</span><span class="p" data-group-id="3635353046-2">}</span><span class="gp unselectable">
│ │ │ +7&gt; </span><span class="nc">test</span><span class="p">:</span><span class="nf">example_fun</span><span class="p" data-group-id="3635353046-3">(</span><span class="ss">arg1</span><span class="p">,</span><span class="s">&quot;this is the second argument&quot;</span><span class="p" data-group-id="3635353046-3">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception error: my_error
│ │ │       in function  test:example_fun/2
│ │ │           called as test:example_fun(arg1,&quot;this is the second argument&quot;)</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="error/3">
│ │ │  
│ │ │ @@ -12456,18 +12456,18 @@
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Raises an exception of class <code class="inline">exit</code> with exit reason <code class="inline">Reason</code>.</p><p>As evaluating this function causes an exception to be raised, it has no return value.</p><p>The intent of the exception class <code class="inline">exit</code> is that the current process should be
│ │ │  stopped (for example when a message telling a process to stop is received).</p><p>This function differ from <a href="#error/1"><code class="inline">error/1,2,3</code></a> by causing an exception of
│ │ │  a different class and by having a reason that does not include the list of
│ │ │  functions from the call stack.</p><p>See the guide about <a href="../../../doc/system/errors.html">errors and error handling</a> for
│ │ │ -additional information.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">exit</span><span class="p" data-group-id="0454285098-1">(</span><span class="ss">foobar</span><span class="p" data-group-id="0454285098-1">)</span><span class="p">.</span><span class="w">
│ │ │ +additional information.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">exit</span><span class="p" data-group-id="3645050149-1">(</span><span class="ss">foobar</span><span class="p" data-group-id="3645050149-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="gt">** exception exit: foobar</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="0454285098-2">(</span><span class="ss">foobar</span><span class="p" data-group-id="0454285098-2">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0454285098-3">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="ss">foobar</span><span class="p" data-group-id="0454285098-3">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>If a process calls <a href="#exit/1"><code class="inline">exit(kill)</code></a> and does not catch the exception,
│ │ │ +&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">exit</span><span class="p" data-group-id="3645050149-2">(</span><span class="ss">foobar</span><span class="p" data-group-id="3645050149-2">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3645050149-3">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="ss">foobar</span><span class="p" data-group-id="3645050149-3">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>If a process calls <a href="#exit/1"><code class="inline">exit(kill)</code></a> and does not catch the exception,
│ │ │  it will terminate with exit reason <code class="inline">kill</code> and also emit exit signals with exit
│ │ │  reason <code class="inline">kill</code> (not <code class="inline">killed</code>) to all linked processes. Such exit signals with
│ │ │  exit reason <code class="inline">kill</code> can be trapped by the linked processes. Note that this
│ │ │  means that signals with exit reason <code class="inline">kill</code> behave differently depending on how
│ │ │  they are sent because the signal will be untrappable if a process sends such a
│ │ │  signal to another process with <a href="#exit/2"><code class="inline">erlang:exit/2</code></a>.</p></section>
│ │ │    </section>
│ │ │ @@ -12660,19 +12660,19 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> get() -> [{Key, Val}] when Key :: <a href="#t:term/0">term</a>(), Val :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the process dictionary as a list of <code class="inline">{Key, Val}</code> tuples. The items in
│ │ │ -the returned list can be in any order.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="0551261830-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="ss">merry</span><span class="p" data-group-id="0551261830-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="0551261830-2">(</span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">lambs</span><span class="p" data-group-id="0551261830-2">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="0551261830-3">(</span><span class="ss">key3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="0551261830-4">{</span><span class="ss">are</span><span class="p">,</span><span class="w"> </span><span class="ss">playing</span><span class="p" data-group-id="0551261830-4">}</span><span class="p" data-group-id="0551261830-3">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">get</span><span class="p" data-group-id="0551261830-5">(</span><span class="p" data-group-id="0551261830-5">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="0551261830-6">[</span><span class="p" data-group-id="0551261830-7">{</span><span class="ss">key1</span><span class="p">,</span><span class="ss">merry</span><span class="p" data-group-id="0551261830-7">}</span><span class="p">,</span><span class="p" data-group-id="0551261830-8">{</span><span class="ss">key2</span><span class="p">,</span><span class="ss">lambs</span><span class="p" data-group-id="0551261830-8">}</span><span class="p">,</span><span class="p" data-group-id="0551261830-9">{</span><span class="ss">key3</span><span class="p">,</span><span class="p" data-group-id="0551261830-10">{</span><span class="ss">are</span><span class="p">,</span><span class="ss">playing</span><span class="p" data-group-id="0551261830-10">}</span><span class="p" data-group-id="0551261830-9">}</span><span class="p" data-group-id="0551261830-6">]</span></code></pre>
│ │ │ +the returned list can be in any order.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="3532967225-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="ss">merry</span><span class="p" data-group-id="3532967225-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="3532967225-2">(</span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">lambs</span><span class="p" data-group-id="3532967225-2">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="3532967225-3">(</span><span class="ss">key3</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3532967225-4">{</span><span class="ss">are</span><span class="p">,</span><span class="w"> </span><span class="ss">playing</span><span class="p" data-group-id="3532967225-4">}</span><span class="p" data-group-id="3532967225-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">get</span><span class="p" data-group-id="3532967225-5">(</span><span class="p" data-group-id="3532967225-5">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3532967225-6">[</span><span class="p" data-group-id="3532967225-7">{</span><span class="ss">key1</span><span class="p">,</span><span class="ss">merry</span><span class="p" data-group-id="3532967225-7">}</span><span class="p">,</span><span class="p" data-group-id="3532967225-8">{</span><span class="ss">key2</span><span class="p">,</span><span class="ss">lambs</span><span class="p" data-group-id="3532967225-8">}</span><span class="p">,</span><span class="p" data-group-id="3532967225-9">{</span><span class="ss">key3</span><span class="p">,</span><span class="p" data-group-id="3532967225-10">{</span><span class="ss">are</span><span class="p">,</span><span class="ss">playing</span><span class="p" data-group-id="3532967225-10">}</span><span class="p" data-group-id="3532967225-9">}</span><span class="p" data-group-id="3532967225-6">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="get/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#get/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12695,19 +12695,19 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> get(Key) -> Val | undefined when Key :: <a href="#t:term/0">term</a>(), Val :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the value <code class="inline">Val</code> associated with <code class="inline">Key</code> in the process dictionary, or
│ │ │  <code class="inline">undefined</code> if <code class="inline">Key</code> does not exist.</p><p>The expected time complexity for the current implementation of this function is
│ │ │  O(<code class="inline">1</code>) and the worst case time complexity is O(<code class="inline">N</code>), where <code class="inline">N</code> is the number of
│ │ │ -items in the process dictionary.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="6798515356-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="ss">merry</span><span class="p" data-group-id="6798515356-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="6798515356-2">(</span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">lambs</span><span class="p" data-group-id="6798515356-2">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="6798515356-3">(</span><span class="p" data-group-id="6798515356-4">{</span><span class="ss">any</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6798515356-5">[</span><span class="ss">valid</span><span class="p">,</span><span class="w"> </span><span class="ss">term</span><span class="p" data-group-id="6798515356-5">]</span><span class="p" data-group-id="6798515356-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6798515356-6">{</span><span class="ss">are</span><span class="p">,</span><span class="w"> </span><span class="ss">playing</span><span class="p" data-group-id="6798515356-6">}</span><span class="p" data-group-id="6798515356-3">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">get</span><span class="p" data-group-id="6798515356-7">(</span><span class="p" data-group-id="6798515356-8">{</span><span class="ss">any</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6798515356-9">[</span><span class="ss">valid</span><span class="p">,</span><span class="w"> </span><span class="ss">term</span><span class="p" data-group-id="6798515356-9">]</span><span class="p" data-group-id="6798515356-8">}</span><span class="p" data-group-id="6798515356-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6798515356-10">{</span><span class="ss">are</span><span class="p">,</span><span class="ss">playing</span><span class="p" data-group-id="6798515356-10">}</span></code></pre>
│ │ │ +items in the process dictionary.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="8033930147-1">(</span><span class="ss">key1</span><span class="p">,</span><span class="w"> </span><span class="ss">merry</span><span class="p" data-group-id="8033930147-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="8033930147-2">(</span><span class="ss">key2</span><span class="p">,</span><span class="w"> </span><span class="ss">lambs</span><span class="p" data-group-id="8033930147-2">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="8033930147-3">(</span><span class="p" data-group-id="8033930147-4">{</span><span class="ss">any</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8033930147-5">[</span><span class="ss">valid</span><span class="p">,</span><span class="w"> </span><span class="ss">term</span><span class="p" data-group-id="8033930147-5">]</span><span class="p" data-group-id="8033930147-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8033930147-6">{</span><span class="ss">are</span><span class="p">,</span><span class="w"> </span><span class="ss">playing</span><span class="p" data-group-id="8033930147-6">}</span><span class="p" data-group-id="8033930147-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">get</span><span class="p" data-group-id="8033930147-7">(</span><span class="p" data-group-id="8033930147-8">{</span><span class="ss">any</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8033930147-9">[</span><span class="ss">valid</span><span class="p">,</span><span class="w"> </span><span class="ss">term</span><span class="p" data-group-id="8033930147-9">]</span><span class="p" data-group-id="8033930147-8">}</span><span class="p" data-group-id="8033930147-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8033930147-10">{</span><span class="ss">are</span><span class="p">,</span><span class="ss">playing</span><span class="p" data-group-id="8033930147-10">}</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="get_keys/0">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#get_keys/0" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12730,19 +12730,19 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> get_keys() -> [Key] when Key :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a list of all keys present in the process dictionary. The items in the
│ │ │ -returned list can be in any order.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="7148561498-1">(</span><span class="ss">dog</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7148561498-2">{</span><span class="ss">animal</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="7148561498-2">}</span><span class="p" data-group-id="7148561498-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="7148561498-3">(</span><span class="ss">cow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7148561498-4">{</span><span class="ss">animal</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="7148561498-4">}</span><span class="p" data-group-id="7148561498-3">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="7148561498-5">(</span><span class="ss">lamb</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7148561498-6">{</span><span class="ss">animal</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="7148561498-6">}</span><span class="p" data-group-id="7148561498-5">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">get_keys</span><span class="p" data-group-id="7148561498-7">(</span><span class="p" data-group-id="7148561498-7">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="7148561498-8">[</span><span class="ss">dog</span><span class="p">,</span><span class="ss">cow</span><span class="p">,</span><span class="ss">lamb</span><span class="p" data-group-id="7148561498-8">]</span></code></pre>
│ │ │ +returned list can be in any order.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="1604005999-1">(</span><span class="ss">dog</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1604005999-2">{</span><span class="ss">animal</span><span class="p">,</span><span class="mi">1</span><span class="p" data-group-id="1604005999-2">}</span><span class="p" data-group-id="1604005999-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="1604005999-3">(</span><span class="ss">cow</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1604005999-4">{</span><span class="ss">animal</span><span class="p">,</span><span class="mi">2</span><span class="p" data-group-id="1604005999-4">}</span><span class="p" data-group-id="1604005999-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="1604005999-5">(</span><span class="ss">lamb</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1604005999-6">{</span><span class="ss">animal</span><span class="p">,</span><span class="mi">3</span><span class="p" data-group-id="1604005999-6">}</span><span class="p" data-group-id="1604005999-5">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">get_keys</span><span class="p" data-group-id="1604005999-7">(</span><span class="p" data-group-id="1604005999-7">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1604005999-8">[</span><span class="ss">dog</span><span class="p">,</span><span class="ss">cow</span><span class="p">,</span><span class="ss">lamb</span><span class="p" data-group-id="1604005999-8">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="get_keys/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#get_keys/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12763,22 +12763,22 @@
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> get_keys(Val) -> [Key] when Val :: <a href="#t:term/0">term</a>(), Key :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a list of keys that are associated with the value <code class="inline">Val</code> in the process
│ │ │ -dictionary. The items in the returned list can be in any order.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="6787917941-1">(</span><span class="ss">mary</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787917941-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6787917941-2">}</span><span class="p" data-group-id="6787917941-1">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="6787917941-3">(</span><span class="ss">had</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787917941-4">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6787917941-4">}</span><span class="p" data-group-id="6787917941-3">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="6787917941-5">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787917941-6">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6787917941-6">}</span><span class="p" data-group-id="6787917941-5">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="6787917941-7">(</span><span class="ss">little</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787917941-8">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6787917941-8">}</span><span class="p" data-group-id="6787917941-7">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="6787917941-9">(</span><span class="ss">dog</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787917941-10">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="6787917941-10">}</span><span class="p" data-group-id="6787917941-9">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">put</span><span class="p" data-group-id="6787917941-11">(</span><span class="ss">lamb</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6787917941-12">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6787917941-12">}</span><span class="p" data-group-id="6787917941-11">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="nf">get_keys</span><span class="p" data-group-id="6787917941-13">(</span><span class="p" data-group-id="6787917941-14">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="6787917941-14">}</span><span class="p" data-group-id="6787917941-13">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6787917941-15">[</span><span class="ss">mary</span><span class="p">,</span><span class="ss">had</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">little</span><span class="p">,</span><span class="ss">lamb</span><span class="p" data-group-id="6787917941-15">]</span></code></pre>
│ │ │ +dictionary. The items in the returned list can be in any order.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">put</span><span class="p" data-group-id="2053776482-1">(</span><span class="ss">mary</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2053776482-2">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2053776482-2">}</span><span class="p" data-group-id="2053776482-1">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="2053776482-3">(</span><span class="ss">had</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2053776482-4">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2053776482-4">}</span><span class="p" data-group-id="2053776482-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="2053776482-5">(</span><span class="ss">a</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2053776482-6">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2053776482-6">}</span><span class="p" data-group-id="2053776482-5">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="2053776482-7">(</span><span class="ss">little</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2053776482-8">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2053776482-8">}</span><span class="p" data-group-id="2053776482-7">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="2053776482-9">(</span><span class="ss">dog</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2053776482-10">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p" data-group-id="2053776482-10">}</span><span class="p" data-group-id="2053776482-9">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">put</span><span class="p" data-group-id="2053776482-11">(</span><span class="ss">lamb</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2053776482-12">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2053776482-12">}</span><span class="p" data-group-id="2053776482-11">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">get_keys</span><span class="p" data-group-id="2053776482-13">(</span><span class="p" data-group-id="2053776482-14">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p" data-group-id="2053776482-14">}</span><span class="p" data-group-id="2053776482-13">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="2053776482-15">[</span><span class="ss">mary</span><span class="p">,</span><span class="ss">had</span><span class="p">,</span><span class="ss">a</span><span class="p">,</span><span class="ss">little</span><span class="p">,</span><span class="ss">lamb</span><span class="p" data-group-id="2053776482-15">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="group_leader/0">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#group_leader/0" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -12925,17 +12925,17 @@
│ │ │  <p><code class="inline">Pid</code> must refer to a process at the local node.</p><p>Returns <code class="inline">true</code> if the process exists and is alive, that is, is not exiting and
│ │ │  has not exited. Otherwise returns <code class="inline">false</code>.</p><p>If process <code class="inline">P1</code> calls <a href="#is_process_alive/1"><code class="inline">is_process_alive(P2Pid)</code></a> it is
│ │ │  guaranteed that all signals, sent from <code class="inline">P1</code> to <code class="inline">P2</code> (<code class="inline">P2</code> is the process with
│ │ │  identifier <code class="inline">P2Pid</code>) before the call, will be delivered to <code class="inline">P2</code> before the
│ │ │  aliveness of <code class="inline">P2</code> is checked. This guarantee means that one can use
│ │ │  <a href="#is_process_alive/1"><code class="inline">is_process_alive/1</code></a> to let a process <code class="inline">P1</code> wait until a
│ │ │  process <code class="inline">P2</code>, which has got an exit signal with reason <code class="inline">kill</code> from P1, is
│ │ │ -killed.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">exit</span><span class="p" data-group-id="7730706216-1">(</span><span class="n">P2Pid</span><span class="p">,</span><span class="w"> </span><span class="ss">kill</span><span class="p" data-group-id="7730706216-1">)</span><span class="p">,</span><span class="w">
│ │ │ +killed.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">exit</span><span class="p" data-group-id="0933701491-1">(</span><span class="n">P2Pid</span><span class="p">,</span><span class="w"> </span><span class="ss">kill</span><span class="p" data-group-id="0933701491-1">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="c1">% P2 might not be killed</span><span class="w">
│ │ │ -</span><span class="nf">is_process_alive</span><span class="p" data-group-id="7730706216-2">(</span><span class="n">P2Pid</span><span class="p" data-group-id="7730706216-2">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">is_process_alive</span><span class="p" data-group-id="0933701491-2">(</span><span class="n">P2Pid</span><span class="p" data-group-id="0933701491-2">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="c1">% P2 is not alive (the call above always return false)</span></code></pre><p>See the documentation about <a href="../../../doc/system/ref_man_processes.html#signals">signals</a>
│ │ │  and <a href="#exit/2">erlang:exit/2</a> for more information about signals and exit
│ │ │  signals.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="link/1">
│ │ │  
│ │ │ @@ -13016,24 +13016,24 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> monitor(process, <a href="#t:monitor_process_identifier/0">monitor_process_identifier</a>()) -> MonitorRef when MonitorRef :: <a href="#t:reference/0">reference</a>();
│ │ │               (port, <a href="#t:monitor_port_identifier/0">monitor_port_identifier</a>()) -> MonitorRef when MonitorRef :: <a href="#t:reference/0">reference</a>();
│ │ │               (time_offset, clock_service) -> MonitorRef when MonitorRef :: <a href="#t:reference/0">reference</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Sends a monitor request of type <code class="inline">Type</code> to the entity identified by <code class="inline">Item</code>.</p><p id="monitor_message">If the monitored entity does not exist or it changes monitored state, the caller
│ │ │ -of <a href="#monitor/2"><code class="inline">monitor/2</code></a> is notified by a message on the following format:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="3224224214-1">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Object</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="3224224214-1">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The monitor request is an asynchronous signal. That is, it takes time before
│ │ │ +of <a href="#monitor/2"><code class="inline">monitor/2</code></a> is notified by a message on the following format:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7566392856-1">{</span><span class="n">Tag</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Object</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="7566392856-1">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The monitor request is an asynchronous signal. That is, it takes time before
│ │ │  the signal reaches its destination.</p></section><p><code class="inline">Type</code> can be one of the following atoms: <code class="inline">process</code>, <code class="inline">port</code> or <code class="inline">time_offset</code>.</p><p>A <code class="inline">process</code> or <code class="inline">port</code> monitor is triggered only once, after that it is removed
│ │ │  from both monitoring process and the monitored entity. Monitors are fired when
│ │ │  the monitored process or port terminates, does not exist at the moment of
│ │ │  creation, or if the connection to it is lost. If the connection to it is lost,
│ │ │  we do not know if it still exists. The monitoring is also turned off when
│ │ │  <a href="#demonitor/1"><code class="inline">demonitor/1</code></a> is called.</p><p>A <code class="inline">process</code> or <code class="inline">port</code> monitor by name resolves the <code class="inline">RegisteredName</code> to <a href="#t:pid/0"><code class="inline">pid/0</code></a>
│ │ │  or <a href="#t:port/0"><code class="inline">port/0</code></a> only once at the moment of monitor instantiation, later changes to
│ │ │  the name registration will not affect the existing monitor.</p><p>When a <code class="inline">process</code> or <code class="inline">port</code> monitor is triggered, a <code class="inline">'DOWN'</code> message is sent that
│ │ │ -has the following pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="8205730109-1">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Object</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="8205730109-1">}</span></code></pre><p>In the monitor message <code class="inline">MonitorRef</code> and <code class="inline">Type</code> are the same as described
│ │ │ +has the following pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="7010823815-1">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Object</span><span class="p">,</span><span class="w"> </span><span class="n">Info</span><span class="p" data-group-id="7010823815-1">}</span></code></pre><p>In the monitor message <code class="inline">MonitorRef</code> and <code class="inline">Type</code> are the same as described
│ │ │  earlier, and:</p><ul><li><p><strong><code class="inline">Object</code></strong> - The monitored entity, which triggered the event. When
│ │ │  monitoring a process or a local port, <code class="inline">Object</code> will be equal to the <a href="#t:pid/0"><code class="inline">pid/0</code></a>
│ │ │  or <a href="#t:port/0"><code class="inline">port/0</code></a> that was being monitored. When monitoring process or port by
│ │ │  name, <code class="inline">Object</code> will have format <code class="inline">{RegisteredName, Node}</code> where
│ │ │  <code class="inline">RegisteredName</code> is the name which has been used with
│ │ │  <a href="#monitor/2"><code class="inline">monitor/2</code></a> call and <code class="inline">Node</code> is local or remote node name (for
│ │ │  ports monitored by name, <code class="inline">Node</code> is always local node name).</p></li><li><p><strong><code class="inline">Info</code></strong> - Either the exit reason of the process, <code class="inline">noproc</code> (process or port
│ │ │ @@ -13069,15 +13069,15 @@
│ │ │  offset is changed when the runtime system detects that the
│ │ │  <a href="time_correction.html#os-system-time">OS system time</a> has changed. The runtime
│ │ │  system does, however, not detect this immediately when it occurs. A task
│ │ │  checking the time offset is scheduled to execute at least once a minute, so
│ │ │  under normal operation this is to be detected within a minute, but during
│ │ │  heavy load it can take longer time.</p><p>The monitor is <em>not</em> automatically removed after it has been triggered. That
│ │ │  is, repeated changes of the time offset trigger the monitor repeatedly.</p><p>When the monitor is triggered a <code class="inline">'CHANGE'</code> message is sent to the monitoring
│ │ │ -process. A <code class="inline">'CHANGE'</code> message has the following pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="9087171077-1">{</span><span class="ss">&#39;CHANGE&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Item</span><span class="p">,</span><span class="w"> </span><span class="n">NewTimeOffset</span><span class="p" data-group-id="9087171077-1">}</span></code></pre><p>where <code class="inline">MonitorRef</code>, <code class="inline">Type</code>, and <code class="inline">Item</code> are the same as described above, and
│ │ │ +process. A <code class="inline">'CHANGE'</code> message has the following pattern:</p><pre><code class="makeup erlang" translate="no"><span class="p" data-group-id="0845849352-1">{</span><span class="ss">&#39;CHANGE&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">MonitorRef</span><span class="p">,</span><span class="w"> </span><span class="n">Type</span><span class="p">,</span><span class="w"> </span><span class="n">Item</span><span class="p">,</span><span class="w"> </span><span class="n">NewTimeOffset</span><span class="p" data-group-id="0845849352-1">}</span></code></pre><p>where <code class="inline">MonitorRef</code>, <code class="inline">Type</code>, and <code class="inline">Item</code> are the same as described above, and
│ │ │  <code class="inline">NewTimeOffset</code> is the new time offset.</p><p>When the <code class="inline">'CHANGE'</code> message has been received you are guaranteed not to
│ │ │  retrieve the old time offset when calling
│ │ │  <a href="#time_offset/0"><code class="inline">erlang:time_offset/0</code></a>. Notice that you can observe the
│ │ │  change of the time offset when calling <a href="#time_offset/0"><code class="inline">erlang:time_offset/0</code></a> before you get
│ │ │  the <code class="inline">'CHANGE'</code> message.</p><p>Available since OTP 18.0.</p></li></ul><p>Making several calls to <a href="#monitor/2"><code class="inline">monitor/2</code></a> for the same <code class="inline">Item</code> and/or
│ │ │  <code class="inline">Type</code> is not an error; it results in as many independent monitoring instances.</p><p>The monitor functionality is expected to be extended. That is, other <code class="inline">Type</code>s and
│ │ │  <code class="inline">Item</code>s are expected to be supported in a future release.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>If or when <a href="#monitor/2"><code class="inline">monitor/2</code></a> is extended, other possible values for
│ │ │ @@ -13133,78 +13133,78 @@
│ │ │  via the alias is received. When a reply message is received via the alias
│ │ │  the monitor will also be automatically removed. This is useful in
│ │ │  client/server scenarios when a client monitors the server and will get the
│ │ │  reply via the alias. Once the response is received both the alias and the
│ │ │  monitor will be automatically removed regardless of whether the response is
│ │ │  a reply or a <code class="inline">'DOWN'</code> message. The alias can also still be deactivated via a
│ │ │  call to <a href="#unalias/1"><code class="inline">unalias/1</code></a>. Note that if the alias is removed using
│ │ │ -the <a href="#unalias/1"><code class="inline">unalias/1</code></a> BIF, the monitor will still be left active.</p></li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server</span><span class="p" data-group-id="6614639735-1">(</span><span class="p" data-group-id="6614639735-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +the <a href="#unalias/1"><code class="inline">unalias/1</code></a> BIF, the monitor will still be left active.</p></li></ul><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server</span><span class="p" data-group-id="1971048229-1">(</span><span class="p" data-group-id="1971048229-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="6614639735-2">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="6614639735-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">perform_request</span><span class="p" data-group-id="6614639735-3">(</span><span class="n">Request</span><span class="p" data-group-id="6614639735-3">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">AliasReqId</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6614639735-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6614639735-4">}</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1971048229-2">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="1971048229-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">perform_request</span><span class="p" data-group-id="1971048229-3">(</span><span class="n">Request</span><span class="p" data-group-id="1971048229-3">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">AliasReqId</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1971048229-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="1971048229-4">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">server</span><span class="p" data-group-id="6614639735-5">(</span><span class="p" data-group-id="6614639735-5">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">server</span><span class="p" data-group-id="1971048229-5">(</span><span class="p" data-group-id="1971048229-5">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="6614639735-6">(</span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="6614639735-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">AliasMonReqId</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="6614639735-7">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6614639735-8">[</span><span class="p" data-group-id="6614639735-9">{</span><span class="ss">alias</span><span class="p">,</span><span class="w"> </span><span class="ss">reply_demonitor</span><span class="p" data-group-id="6614639735-9">}</span><span class="p" data-group-id="6614639735-8">]</span><span class="p" data-group-id="6614639735-7">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ServerPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6614639735-10">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasMonReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="6614639735-10">}</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="1971048229-6">(</span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="1971048229-6">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">AliasMonReqId</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="1971048229-7">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1971048229-8">[</span><span class="p" data-group-id="1971048229-9">{</span><span class="ss">alias</span><span class="p">,</span><span class="w"> </span><span class="ss">reply_demonitor</span><span class="p" data-group-id="1971048229-9">}</span><span class="p" data-group-id="1971048229-8">]</span><span class="p" data-group-id="1971048229-7">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ServerPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="1971048229-10">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">AliasMonReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="1971048229-10">}</span><span class="p">,</span><span class="w">
│ │ │      </span><span class="c1">%% Alias as well as monitor will be automatically deactivated if we</span><span class="w">
│ │ │      </span><span class="c1">%% receive a reply or a &#39;DOWN&#39; message since we used &#39;reply_demonitor&#39;</span><span class="w">
│ │ │      </span><span class="c1">%% as unalias option...</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="6614639735-11">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasMonReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6614639735-11">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1971048229-11">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">AliasMonReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="1971048229-11">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │              </span><span class="n">Result</span><span class="p">;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="6614639735-12">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">AliasMonReqId</span><span class="p">,</span><span class="w"> </span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ExitReason</span><span class="p" data-group-id="6614639735-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="nf">error</span><span class="p" data-group-id="6614639735-13">(</span><span class="n">ExitReason</span><span class="p" data-group-id="6614639735-13">)</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1971048229-12">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">AliasMonReqId</span><span class="p">,</span><span class="w"> </span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ExitReason</span><span class="p" data-group-id="1971048229-12">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="nf">error</span><span class="p" data-group-id="1971048229-13">(</span><span class="n">ExitReason</span><span class="p" data-group-id="1971048229-13">)</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">.</span></code></pre><p>Note that both the server and the client in this example must be executing on
│ │ │  at least OTP 24 systems in order for this to work.</p><p>For more information on process aliases see the
│ │ │  <a href="../../../doc/system/ref_man_processes.html#process-aliases"><em>Process Aliases</em></a> section
│ │ │  of the <em>Erlang Reference Manual</em>.</p></li><li><p><strong><code class="inline">{tag, UserDefinedTag}</code></strong> - Replace the default <code class="inline">Tag</code> with <code class="inline">UserDefinedTag</code>
│ │ │  in the <a href="#monitor_message">monitor message</a> delivered when the
│ │ │  monitor is triggered. For example, when monitoring a process, the <code class="inline">'DOWN'</code> tag
│ │ │  in the down message will be replaced by <code class="inline">UserDefinedTag</code>.</p><p>An example of how the <code class="inline">{tag, UserDefinedTag}</code> option can be used in order to
│ │ │  enable the new
│ │ │  <a href="../../../doc/system/eff_guide_processes.html#receiving-messages">selective receive optimization</a>,
│ │ │ -introduced in OTP 24, when making multiple requests to different servers:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server</span><span class="p" data-group-id="7596102900-1">(</span><span class="p" data-group-id="7596102900-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +introduced in OTP 24, when making multiple requests to different servers:</p><pre><code class="makeup erlang" translate="no"><span class="nf">server</span><span class="p" data-group-id="6902956764-1">(</span><span class="p" data-group-id="6902956764-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="k">receive</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="7596102900-2">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="7596102900-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -            </span><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">perform_request</span><span class="p" data-group-id="7596102900-3">(</span><span class="n">Request</span><span class="p" data-group-id="7596102900-3">)</span><span class="p">,</span><span class="w">
│ │ │ -            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7596102900-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7596102900-5">(</span><span class="p" data-group-id="7596102900-5">)</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7596102900-4">}</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="6902956764-2">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="n">From</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="6902956764-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +            </span><span class="n">Result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">perform_request</span><span class="p" data-group-id="6902956764-3">(</span><span class="n">Request</span><span class="p" data-group-id="6902956764-3">)</span><span class="p">,</span><span class="w">
│ │ │ +            </span><span class="n">From</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6902956764-4">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6902956764-5">(</span><span class="p" data-group-id="6902956764-5">)</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6902956764-4">}</span><span class="w">
│ │ │      </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">server</span><span class="p" data-group-id="7596102900-6">(</span><span class="p" data-group-id="7596102900-6">)</span><span class="p">.</span><span class="w">
│ │ │ +    </span><span class="nf">server</span><span class="p" data-group-id="6902956764-6">(</span><span class="p" data-group-id="6902956764-6">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">client</span><span class="p" data-group-id="7596102900-7">(</span><span class="n">ServerPids</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="7596102900-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_list</span><span class="p" data-group-id="7596102900-8">(</span><span class="n">ServerPids</span><span class="p" data-group-id="7596102900-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -    </span><span class="n">ReqId</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="7596102900-9">(</span><span class="p" data-group-id="7596102900-9">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="7596102900-10">(</span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="7596102900-11">(</span><span class="n">ServerPid</span><span class="p" data-group-id="7596102900-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                          </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="7596102900-12">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w">
│ │ │ -                                      </span><span class="p" data-group-id="7596102900-13">[</span><span class="p" data-group-id="7596102900-14">{</span><span class="ss">tag</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7596102900-15">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p" data-group-id="7596102900-15">}</span><span class="p" data-group-id="7596102900-14">}</span><span class="p" data-group-id="7596102900-13">]</span><span class="p" data-group-id="7596102900-12">)</span><span class="p">,</span><span class="w">
│ │ │ -                          </span><span class="n">ServerPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="7596102900-16">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="7596102900-17">(</span><span class="p" data-group-id="7596102900-17">)</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="7596102900-16">}</span><span class="w">
│ │ │ +</span><span class="nf">client</span><span class="p" data-group-id="6902956764-7">(</span><span class="n">ServerPids</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="6902956764-7">)</span><span class="w"> </span><span class="k">when</span><span class="w"> </span><span class="nf">is_list</span><span class="p" data-group-id="6902956764-8">(</span><span class="n">ServerPids</span><span class="p" data-group-id="6902956764-8">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="n">ReqId</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">make_ref</span><span class="p" data-group-id="6902956764-9">(</span><span class="p" data-group-id="6902956764-9">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foreach</span><span class="p" data-group-id="6902956764-10">(</span><span class="nf">fun</span><span class="w"> </span><span class="p" data-group-id="6902956764-11">(</span><span class="n">ServerPid</span><span class="p" data-group-id="6902956764-11">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                          </span><span class="p">_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">monitor</span><span class="p" data-group-id="6902956764-12">(</span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w">
│ │ │ +                                      </span><span class="p" data-group-id="6902956764-13">[</span><span class="p" data-group-id="6902956764-14">{</span><span class="ss">tag</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6902956764-15">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p" data-group-id="6902956764-15">}</span><span class="p" data-group-id="6902956764-14">}</span><span class="p" data-group-id="6902956764-13">]</span><span class="p" data-group-id="6902956764-12">)</span><span class="p">,</span><span class="w">
│ │ │ +                          </span><span class="n">ServerPid</span><span class="w"> </span><span class="o">!</span><span class="w"> </span><span class="p" data-group-id="6902956764-16">{</span><span class="ss">request</span><span class="p">,</span><span class="w"> </span><span class="nf">self</span><span class="p" data-group-id="6902956764-17">(</span><span class="p" data-group-id="6902956764-17">)</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Request</span><span class="p" data-group-id="6902956764-16">}</span><span class="w">
│ │ │                    </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -                  </span><span class="n">ServerPids</span><span class="p" data-group-id="7596102900-10">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">receive_replies</span><span class="p" data-group-id="7596102900-18">(</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="7596102900-19">(</span><span class="n">ServerPids</span><span class="p" data-group-id="7596102900-19">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7596102900-20">[</span><span class="p" data-group-id="7596102900-20">]</span><span class="p" data-group-id="7596102900-18">)</span><span class="p">.</span><span class="w">
│ │ │ +                  </span><span class="n">ServerPids</span><span class="p" data-group-id="6902956764-10">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="nf">receive_replies</span><span class="p" data-group-id="6902956764-18">(</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="nf">length</span><span class="p" data-group-id="6902956764-19">(</span><span class="n">ServerPids</span><span class="p" data-group-id="6902956764-19">)</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6902956764-20">[</span><span class="p" data-group-id="6902956764-20">]</span><span class="p" data-group-id="6902956764-18">)</span><span class="p">.</span><span class="w">
│ │ │  
│ │ │ -</span><span class="nf">receive_replies</span><span class="p" data-group-id="7596102900-21">(</span><span class="p">_</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7596102900-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">receive_replies</span><span class="p" data-group-id="6902956764-21">(</span><span class="p">_</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6902956764-21">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="n">Acc</span><span class="p">;</span><span class="w">
│ │ │ -</span><span class="nf">receive_replies</span><span class="p" data-group-id="7596102900-22">(</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7596102900-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +</span><span class="nf">receive_replies</span><span class="p" data-group-id="6902956764-22">(</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="p">,</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6902956764-22">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │      </span><span class="c1">%% The compiler will detect that we match on the &#39;ReqId&#39;</span><span class="w">
│ │ │      </span><span class="c1">%% reference in all clauses, and will enable the selective</span><span class="w">
│ │ │      </span><span class="c1">%% receive optimization which makes the receive able to</span><span class="w">
│ │ │      </span><span class="c1">%% skip past all messages present in the message queue at</span><span class="w">
│ │ │      </span><span class="c1">%% the time when the &#39;ReqId&#39; reference was created...</span><span class="w">
│ │ │      </span><span class="n">Res</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">receive</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7596102900-23">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7596102900-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="6902956764-23">{</span><span class="ss">reply</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6902956764-23">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │                    </span><span class="c1">%% Here we typically would have deactivated the</span><span class="w">
│ │ │                    </span><span class="c1">%% monitor by a call to demonitor(Mon, [flush]) but</span><span class="w">
│ │ │                    </span><span class="c1">%% we ignore this in this example for simplicity...</span><span class="w">
│ │ │ -                  </span><span class="p" data-group-id="7596102900-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="7596102900-24">}</span><span class="p">;</span><span class="w">
│ │ │ -              </span><span class="p" data-group-id="7596102900-25">{</span><span class="p" data-group-id="7596102900-26">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p" data-group-id="7596102900-26">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Mon</span><span class="p">,</span><span class="w"> </span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ExitReason</span><span class="p" data-group-id="7596102900-25">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                  </span><span class="p" data-group-id="7596102900-27">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ExitReason</span><span class="p" data-group-id="7596102900-27">}</span><span class="w">
│ │ │ +                  </span><span class="p" data-group-id="6902956764-24">{</span><span class="ss">ok</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">Result</span><span class="p" data-group-id="6902956764-24">}</span><span class="p">;</span><span class="w">
│ │ │ +              </span><span class="p" data-group-id="6902956764-25">{</span><span class="p" data-group-id="6902956764-26">{</span><span class="ss">&#39;DOWN&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">ReqId</span><span class="p" data-group-id="6902956764-26">}</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="n">Mon</span><span class="p">,</span><span class="w"> </span><span class="ss">process</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ExitReason</span><span class="p" data-group-id="6902956764-25">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                  </span><span class="p" data-group-id="6902956764-27">{</span><span class="ss">error</span><span class="p">,</span><span class="w"> </span><span class="n">ServerPid</span><span class="p">,</span><span class="w"> </span><span class="n">ExitReason</span><span class="p" data-group-id="6902956764-27">}</span><span class="w">
│ │ │            </span><span class="k">end</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="nf">receive_replies</span><span class="p" data-group-id="7596102900-28">(</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7596102900-29">[</span><span class="n">Res</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="7596102900-29">]</span><span class="p" data-group-id="7596102900-28">)</span><span class="p">.</span></code></pre><p>In order for this example to work as intended, the client must be executing on
│ │ │ +    </span><span class="nf">receive_replies</span><span class="p" data-group-id="6902956764-28">(</span><span class="n">ReqId</span><span class="p">,</span><span class="w"> </span><span class="n">N</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6902956764-29">[</span><span class="n">Res</span><span class="w"> </span><span class="p">|</span><span class="w"> </span><span class="n">Acc</span><span class="p" data-group-id="6902956764-29">]</span><span class="p" data-group-id="6902956764-28">)</span><span class="p">.</span></code></pre><p>In order for this example to work as intended, the client must be executing on
│ │ │  at least an OTP 24 system, but the servers may execute on older systems.</p></li></ul>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="nif_error/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#nif_error/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -13910,15 +13910,15 @@
│ │ │                    (sensitive, Boolean) -> OldBoolean when Boolean :: <a href="#t:boolean/0">boolean</a>(), OldBoolean :: <a href="#t:boolean/0">boolean</a>();
│ │ │                    ({monitor_nodes, <a href="#t:term/0">term</a>()}, <a href="#t:term/0">term</a>()) -> <a href="#t:term/0">term</a>();
│ │ │                    (monitor_nodes, <a href="#t:term/0">term</a>()) -> <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Sets the process flag indicated to the specified value. Returns the previous value
│ │ │ -of the flag.</p><p><code class="inline">Flag</code> is one of the following:</p><ul><li><pre id="process_flag_async_dist"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="0503558545-1">(</span><span class="ss">async_dist</span><span class="p">,</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="0503558545-2">(</span><span class="p" data-group-id="0503558545-2">)</span><span class="p" data-group-id="0503558545-1">)</span></code></pre><p>Enable or disable <em>fully asynchronous distributed signaling</em> for the calling
│ │ │ +of the flag.</p><p><code class="inline">Flag</code> is one of the following:</p><ul><li><pre id="process_flag_async_dist"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="2558003810-1">(</span><span class="ss">async_dist</span><span class="p">,</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="2558003810-2">(</span><span class="p" data-group-id="2558003810-2">)</span><span class="p" data-group-id="2558003810-1">)</span></code></pre><p>Enable or disable <em>fully asynchronous distributed signaling</em> for the calling
│ │ │  process. When disabled, which is the default, the process sending a distributed
│ │ │  signal will block in the send operation if the buffer for the distribution
│ │ │  channel reach the <a href="erl_cmd.html#%2Bzdbbl">distribution buffer busy limit</a>. The
│ │ │  process will remain blocked until the buffer shrinks enough. This might in some
│ │ │  cases take a substantial amount of time. When <code class="inline">async_dist</code> is enabled, send
│ │ │  operations of distributed signals will always buffer the signal on the outgoing
│ │ │  distribution channel and then immediately return. That is, these send operations
│ │ │ @@ -13935,22 +13935,22 @@
│ │ │  caller.</p><p>The <code class="inline">async_dist</code> flag can also be set on a new process when spawning it using
│ │ │  the <a href="#spawn_opt/4"><code class="inline">spawn_opt()</code></a> BIF with the option
│ │ │  <a href="#spawn_opt_async_dist"><code class="inline">{async_dist, Enable}</code></a>. The default
│ │ │  <code class="inline">async_dist</code> flag to use on newly spawned processes can be set by passing the
│ │ │  command line argument <a href="erl_cmd.html#%2Bpad"><code class="inline">+pad &lt;boolean&gt;</code></a> when starting the
│ │ │  runtime system. If the <code class="inline">+pad &lt;boolean&gt;</code> command line argument is not passed, the
│ │ │  default value of the <code class="inline">async_dist</code> flag will be <code class="inline">false</code>.</p><p>You can inspect the state of the <code class="inline">async_dist</code> process flag of a process by
│ │ │ -calling <a href="#process_info_async_dist"><code class="inline">process_info(Pid, async_dist)</code></a>.</p></li><li><pre id="process_flag_trap_exit"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="2190685343-1">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="2190685343-2">(</span><span class="p" data-group-id="2190685343-2">)</span><span class="p" data-group-id="2190685343-1">)</span></code></pre><p>When <code class="inline">trap_exit</code> is set to <code class="inline">true</code>, exit signals arriving to a process are
│ │ │ +calling <a href="#process_info_async_dist"><code class="inline">process_info(Pid, async_dist)</code></a>.</p></li><li><pre id="process_flag_trap_exit"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="7327523985-1">(</span><span class="ss">trap_exit</span><span class="p">,</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="7327523985-2">(</span><span class="p" data-group-id="7327523985-2">)</span><span class="p" data-group-id="7327523985-1">)</span></code></pre><p>When <code class="inline">trap_exit</code> is set to <code class="inline">true</code>, exit signals arriving to a process are
│ │ │  converted to <code class="inline">{'EXIT', From, Reason}</code> messages, which can be received as
│ │ │  ordinary messages. If <code class="inline">trap_exit</code> is set to <code class="inline">false</code>, the process exits if it
│ │ │  receives an exit signal other than <code class="inline">normal</code> and the exit signal is propagated to
│ │ │ -its linked processes. Application processes are normally not to trap exits.</p><p>See also <a href="#exit/2"><code class="inline">exit/2</code></a>.</p></li><li><pre id="process_flag_error_handler"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="5020630852-1">(</span><span class="ss">error_handler</span><span class="p">,</span><span class="w"> </span><span class="nf">module</span><span class="p" data-group-id="5020630852-2">(</span><span class="p" data-group-id="5020630852-2">)</span><span class="p" data-group-id="5020630852-1">)</span></code></pre><p>Used by a process to redefine the <a href="../../../lib/kernel-10.2.7.2/doc/html/error_handler.html"><code class="inline">error_handler</code></a> for undefined function calls and
│ │ │ +its linked processes. Application processes are normally not to trap exits.</p><p>See also <a href="#exit/2"><code class="inline">exit/2</code></a>.</p></li><li><pre id="process_flag_error_handler"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="7067725556-1">(</span><span class="ss">error_handler</span><span class="p">,</span><span class="w"> </span><span class="nf">module</span><span class="p" data-group-id="7067725556-2">(</span><span class="p" data-group-id="7067725556-2">)</span><span class="p" data-group-id="7067725556-1">)</span></code></pre><p>Used by a process to redefine the <a href="../../../lib/kernel-10.2.7.2/doc/html/error_handler.html"><code class="inline">error_handler</code></a> for undefined function calls and
│ │ │  undefined registered processes. Use this flag with substantial caution, as code
│ │ │ -auto-loading depends on the correct operation of the error handling module.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="0903762577-1">(</span><span class="ss">fullsweep_after</span><span class="p">,</span><span class="w">  </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="0903762577-2">(</span><span class="p" data-group-id="0903762577-2">)</span><span class="p" data-group-id="0903762577-1">)</span></code></pre><p>Changes the maximum number of generational collections before forcing a
│ │ │ -fullsweep for the calling process.</p></li><li><pre id="process_flag_min_heap_size"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="6091082056-1">(</span><span class="ss">min_heap_size</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6091082056-2">(</span><span class="p" data-group-id="6091082056-2">)</span><span class="p" data-group-id="6091082056-1">)</span></code></pre><p>Changes the minimum heap size for the calling process.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="6650164870-1">(</span><span class="ss">min_bin_vheap_size</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6650164870-2">(</span><span class="p" data-group-id="6650164870-2">)</span><span class="p" data-group-id="6650164870-1">)</span></code></pre><p>Changes the minimum binary virtual heap size for the calling process.</p></li><li><pre id="process_flag_max_heap_size"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="3698448601-1">(</span><span class="ss">max_heap_size</span><span class="p">,</span><span class="w"> </span><span class="nf">max_heap_size</span><span class="p" data-group-id="3698448601-2">(</span><span class="p" data-group-id="3698448601-2">)</span><span class="p" data-group-id="3698448601-1">)</span></code></pre><p>This flag sets the maximum heap size for the calling process. If <code class="inline">MaxHeapSize</code>
│ │ │ +auto-loading depends on the correct operation of the error handling module.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="9476827870-1">(</span><span class="ss">fullsweep_after</span><span class="p">,</span><span class="w">  </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="9476827870-2">(</span><span class="p" data-group-id="9476827870-2">)</span><span class="p" data-group-id="9476827870-1">)</span></code></pre><p>Changes the maximum number of generational collections before forcing a
│ │ │ +fullsweep for the calling process.</p></li><li><pre id="process_flag_min_heap_size"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="4845187844-1">(</span><span class="ss">min_heap_size</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4845187844-2">(</span><span class="p" data-group-id="4845187844-2">)</span><span class="p" data-group-id="4845187844-1">)</span></code></pre><p>Changes the minimum heap size for the calling process.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="1788763021-1">(</span><span class="ss">min_bin_vheap_size</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1788763021-2">(</span><span class="p" data-group-id="1788763021-2">)</span><span class="p" data-group-id="1788763021-1">)</span></code></pre><p>Changes the minimum binary virtual heap size for the calling process.</p></li><li><pre id="process_flag_max_heap_size"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="4903800955-1">(</span><span class="ss">max_heap_size</span><span class="p">,</span><span class="w"> </span><span class="nf">max_heap_size</span><span class="p" data-group-id="4903800955-2">(</span><span class="p" data-group-id="4903800955-2">)</span><span class="p" data-group-id="4903800955-1">)</span></code></pre><p>This flag sets the maximum heap size for the calling process. If <code class="inline">MaxHeapSize</code>
│ │ │  is an integer, the system default values for <code class="inline">kill</code> and <code class="inline">error_logger</code> are used.</p><p>For details on how the heap grows, see
│ │ │  <a href="garbagecollection.html#sizing-the-heap">Sizing the heap</a> in the ERTS internal
│ │ │  documentation.</p><ul><li><p><strong><code class="inline">size</code></strong> - The maximum size in words of the process. If set to zero, the
│ │ │  heap size limit is disabled. <code class="inline">badarg</code> is be thrown if the value is smaller
│ │ │  than <a href="#process_flag_min_heap_size"><code class="inline">min_heap_size</code></a>. The size check
│ │ │  is only done when a garbage collection is triggered.</p><p><code class="inline">size</code> is the entire heap of the process when garbage collection is triggered.
│ │ │  This includes all generational heaps, the process stack, any
│ │ │ @@ -13978,27 +13978,27 @@
│ │ │  of it is referred by the process.</p><p>If <code class="inline">include_shared_binaries</code> is not defined in the map, the system default is
│ │ │  used. The default system default is <code class="inline">false</code>. It can be changed by either the
│ │ │  option <a href="erl_cmd.html#%2Bhmaxib">+hmaxib</a> in <a href="erl_cmd.html">erl</a>, or
│ │ │  <a href="#system_flag_max_heap_size"><code class="inline">erlang:system_flag(max_heap_size, MaxHeapSize)</code></a>.</p></li></ul><p>The heap size of a process is quite hard to predict, especially the amount of
│ │ │  memory that is used during the garbage collection. When contemplating using this
│ │ │  option, it is recommended to first run it in production with <code class="inline">kill</code> set to
│ │ │  <code class="inline">false</code> and inspect the log events to see what the normal peak sizes of the
│ │ │ -processes in the system is and then tune the value accordingly.</p></li><li><pre id="process_flag_message_queue_data"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="6223180775-1">(</span><span class="ss">message_queue_data</span><span class="p">,</span><span class="w"> </span><span class="nf">message_queue_data</span><span class="p" data-group-id="6223180775-2">(</span><span class="p" data-group-id="6223180775-2">)</span><span class="p" data-group-id="6223180775-1">)</span></code></pre><p>Determines how messages in the message queue are stored, as follows:</p><ul><li><p><strong><code class="inline">off_heap</code></strong> - <em>All</em> messages in the message queue will be stored outside
│ │ │ +processes in the system is and then tune the value accordingly.</p></li><li><pre id="process_flag_message_queue_data"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="8251269884-1">(</span><span class="ss">message_queue_data</span><span class="p">,</span><span class="w"> </span><span class="nf">message_queue_data</span><span class="p" data-group-id="8251269884-2">(</span><span class="p" data-group-id="8251269884-2">)</span><span class="p" data-group-id="8251269884-1">)</span></code></pre><p>Determines how messages in the message queue are stored, as follows:</p><ul><li><p><strong><code class="inline">off_heap</code></strong> - <em>All</em> messages in the message queue will be stored outside
│ │ │  the process heap. This implies that <em>no</em> messages in the message queue will be
│ │ │  part of a garbage collection of the process.</p></li><li><p><strong><code class="inline">on_heap</code></strong> - All messages in the message queue will eventually be placed on
│ │ │  the process heap. They can, however, be temporarily stored off the heap. This
│ │ │  is how messages have always been stored up until ERTS 8.0.</p></li></ul><p>The default value of the <code class="inline">message_queue_data</code> process flag is determined by the
│ │ │  command-line argument <a href="erl_cmd.html#%2Bhmqd"><code class="inline">+hmqd</code></a> in <a href="erl_cmd.html">erl</a>.</p><p>If the process may potentially accumulate a large number of messages in its
│ │ │  queue it is recommended to set the flag value to <code class="inline">off_heap</code>. This is due to the
│ │ │  fact that the garbage collection of a process that has a large number of
│ │ │  messages stored on the heap can become extremely expensive and the process can
│ │ │  consume large amounts of memory. The performance of the actual message passing
│ │ │  is, however, generally better when the flag value is <code class="inline">on_heap</code>.</p><p>Changing the flag value causes any existing messages to be moved. The move
│ │ │  operation is initiated, but not necessarily completed, by the time the function
│ │ │ -returns.</p></li><li><pre id="process_flag_priority"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="8532797466-1">(</span><span class="ss">priority</span><span class="p">,</span><span class="w"> </span><span class="nf">priority_level</span><span class="p" data-group-id="8532797466-2">(</span><span class="p" data-group-id="8532797466-2">)</span><span class="p" data-group-id="8532797466-1">)</span></code></pre><p>Sets the process priority. <code class="inline">Level</code> is an atom. Four priority levels exist:
│ │ │ +returns.</p></li><li><pre id="process_flag_priority"><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="3416289229-1">(</span><span class="ss">priority</span><span class="p">,</span><span class="w"> </span><span class="nf">priority_level</span><span class="p" data-group-id="3416289229-2">(</span><span class="p" data-group-id="3416289229-2">)</span><span class="p" data-group-id="3416289229-1">)</span></code></pre><p>Sets the process priority. <code class="inline">Level</code> is an atom. Four priority levels exist:
│ │ │  <code class="inline">low</code>, <code class="inline">normal</code>, <code class="inline">high</code>, and <code class="inline">max</code>. Default is <code class="inline">normal</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Priority level <code class="inline">max</code> is reserved for internal use in the Erlang runtime
│ │ │  system, and is <em>not</em> to be used by others.</p></section><p>Internally in each priority level, processes are scheduled in a round robin
│ │ │  fashion.</p><p>Execution of processes on priority <code class="inline">normal</code> and <code class="inline">low</code> are interleaved. Processes
│ │ │  on priority <code class="inline">low</code> are selected for execution less frequently than processes on
│ │ │  priority <code class="inline">normal</code>.</p><p>When runnable processes on priority <code class="inline">high</code> exist, no processes on priority <code class="inline">low</code>
│ │ │  or <code class="inline">normal</code> are selected for execution. Notice however that this does <em>not</em> mean
│ │ │  that no processes on priority <code class="inline">low</code> or <code class="inline">normal</code> can run when processes are
│ │ │ @@ -14019,24 +14019,24 @@
│ │ │  process during the call. Even if this is not the case with one version of the
│ │ │  code that you have no control over, it can be the case in a future version of
│ │ │  it. This can, for example, occur if a <code class="inline">high</code> priority process triggers code
│ │ │  loading, as the code server runs on priority <code class="inline">normal</code>.</p><p>Other priorities than <code class="inline">normal</code> are normally not needed. When other priorities
│ │ │  are used, use them with care, <em>especially</em> priority <code class="inline">high</code>. A process on
│ │ │  priority <code class="inline">high</code> is only to perform work for short periods. Busy looping for long
│ │ │  periods in a <code class="inline">high</code> priority process causes most likely problems, as important
│ │ │ -OTP servers run on priority <code class="inline">normal</code>.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="5576180193-1">(</span><span class="ss">save_calls</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">.</span><span class="p">.</span><span class="mi">10000</span><span class="p" data-group-id="5576180193-1">)</span></code></pre><p><code class="inline">N</code> must be an integer in the interval 0..10000. If <code class="inline">N</code> &gt; 0, call saving is made
│ │ │ +OTP servers run on priority <code class="inline">normal</code>.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="9612603980-1">(</span><span class="ss">save_calls</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">.</span><span class="p">.</span><span class="mi">10000</span><span class="p" data-group-id="9612603980-1">)</span></code></pre><p><code class="inline">N</code> must be an integer in the interval 0..10000. If <code class="inline">N</code> &gt; 0, call saving is made
│ │ │  active for the process. This means that information about the <code class="inline">N</code> most recent
│ │ │  global function calls, BIF calls, sends, and receives made by the process are
│ │ │  saved in a list, which can be retrieved with
│ │ │  <a href="#process_info/2"><code class="inline">process_info(Pid, last_calls)</code></a>. A global function call is
│ │ │  one in which the module of the function is explicitly mentioned. Only a fixed
│ │ │  amount of information is saved, as follows:</p><ul><li>A tuple <code class="inline">{Module, Function, Arity}</code> for function calls</li><li>The atoms <code class="inline">send</code>, <code class="inline">'receive'</code>, and <code class="inline">timeout</code> for sends and receives
│ │ │  (<code class="inline">'receive'</code> when a message is received and <code class="inline">timeout</code> when a receive times
│ │ │  out)</li></ul><p>If <code class="inline">N</code> = 0, call saving is disabled for the process, which is the default.
│ │ │ -Whenever the size of the call saving list is set, its contents are reset.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="0444349671-1">(</span><span class="ss">sensitive</span><span class="p">,</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="0444349671-2">(</span><span class="p" data-group-id="0444349671-2">)</span><span class="p" data-group-id="0444349671-1">)</span></code></pre><p>Sets or clears flag <code class="inline">sensitive</code> for the current process. When a process has been
│ │ │ +Whenever the size of the call saving list is set, its contents are reset.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">process_flag</span><span class="p" data-group-id="0002371673-1">(</span><span class="ss">sensitive</span><span class="p">,</span><span class="w"> </span><span class="nf">boolean</span><span class="p" data-group-id="0002371673-2">(</span><span class="p" data-group-id="0002371673-2">)</span><span class="p" data-group-id="0002371673-1">)</span></code></pre><p>Sets or clears flag <code class="inline">sensitive</code> for the current process. When a process has been
│ │ │  marked as sensitive by calling
│ │ │  <a href="#process_flag/2"><code class="inline">process_flag(sensitive, true)</code></a>, features in the runtime
│ │ │  system that can be used for examining the data or inner working of the process
│ │ │  are silently disabled.</p><p>Features that are disabled include (but are not limited to) the following:</p><ul><li>Tracing. Trace flags can still be set for the process, but no trace messages
│ │ │  of any kind are generated. (If flag <code class="inline">sensitive</code> is turned off, trace messages
│ │ │  are again generated if any trace flags are set.)</li><li>Sequential tracing. The sequential trace token is propagated as usual, but no
│ │ │  sequential trace messages are generated.</li></ul><p><code class="inline">process_info/1,2</code> cannot be used to read out the message queue or the process
│ │ │ @@ -14280,16 +14280,16 @@
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns a list of process identifiers corresponding to all the processes
│ │ │  currently existing on the local node.</p><p>Notice that an exiting process exists, but is not alive. That is,
│ │ │  <a href="#is_process_alive/1"><code class="inline">is_process_alive/1</code></a> returns <code class="inline">false</code> for an exiting
│ │ │  process, but its process identifier is part of the result returned from
│ │ │ -<a href="#processes/0"><code class="inline">processes/0</code></a>.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">processes</span><span class="p" data-group-id="4848957389-1">(</span><span class="p" data-group-id="4848957389-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4848957389-2">[</span><span class="o">&lt;</span><span class="mf">0.0</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.2</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.5</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.7</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.8</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="4848957389-2">]</span></code></pre>
│ │ │ +<a href="#processes/0"><code class="inline">processes/0</code></a>.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">processes</span><span class="p" data-group-id="1062113372-1">(</span><span class="p" data-group-id="1062113372-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1062113372-2">[</span><span class="o">&lt;</span><span class="mf">0.0</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.2</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.4</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.5</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.7</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p">,</span><span class="o">&lt;</span><span class="mf">0.8</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span><span class="p" data-group-id="1062113372-2">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="put/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#put/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -14313,18 +14313,18 @@
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Adds a new <code class="inline">Key</code> to the process dictionary, associated with the value <code class="inline">Val</code>, and
│ │ │  returns <code class="inline">undefined</code>. If <code class="inline">Key</code> exists, the old value is deleted and replaced by
│ │ │  <code class="inline">Val</code>, and the function returns the old value.</p><p>The average time complexity for the current implementation of this function is
│ │ │  O(<code class="inline">1</code>) and the worst case time complexity is O(<code class="inline">N</code>), where <code class="inline">N</code> is the number of
│ │ │ -items in the process dictionary.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">put</span><span class="p" data-group-id="6996708372-1">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">walrus</span><span class="p" data-group-id="6996708372-1">)</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">put</span><span class="p" data-group-id="6996708372-2">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">carpenter</span><span class="p" data-group-id="6996708372-2">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">get</span><span class="p" data-group-id="6996708372-3">(</span><span class="ss">name</span><span class="p" data-group-id="6996708372-3">)</span><span class="p">,</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6996708372-4">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="6996708372-4">}</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6996708372-5">{</span><span class="ss">undefined</span><span class="p">,</span><span class="ss">walrus</span><span class="p">,</span><span class="ss">carpenter</span><span class="p" data-group-id="6996708372-5">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The values stored when <code class="inline">put</code> is evaluated within the scope of a <code class="inline">catch</code> are
│ │ │ +items in the process dictionary.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">X</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">put</span><span class="p" data-group-id="3302539369-1">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">walrus</span><span class="p" data-group-id="3302539369-1">)</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">put</span><span class="p" data-group-id="3302539369-2">(</span><span class="ss">name</span><span class="p">,</span><span class="w"> </span><span class="ss">carpenter</span><span class="p" data-group-id="3302539369-2">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="n">Z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nf">get</span><span class="p" data-group-id="3302539369-3">(</span><span class="ss">name</span><span class="p" data-group-id="3302539369-3">)</span><span class="p">,</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3302539369-4">{</span><span class="n">X</span><span class="p">,</span><span class="w"> </span><span class="n">Y</span><span class="p">,</span><span class="w"> </span><span class="n">Z</span><span class="p" data-group-id="3302539369-4">}</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="3302539369-5">{</span><span class="ss">undefined</span><span class="p">,</span><span class="ss">walrus</span><span class="p">,</span><span class="ss">carpenter</span><span class="p" data-group-id="3302539369-5">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The values stored when <code class="inline">put</code> is evaluated within the scope of a <code class="inline">catch</code> are
│ │ │  not retracted if a <code class="inline">throw</code> is evaluated, or if an error occurs.</p></section>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="raise/3">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#raise/3" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -14395,15 +14395,15 @@
│ │ │        </div>
│ │ │  
│ │ │  <p>Registers the name <code class="inline">RegName</code> with a process identifier (pid) or a port
│ │ │  identifier in the
│ │ │  <a href="../../../doc/system/ref_man_processes.html#runtime-service"><code class="inline">name registry</code></a>.
│ │ │  <code class="inline">RegName</code>, which must be an atom, can be used instead of the pid or port
│ │ │  identifier in send operator (<code class="inline">RegName ! Message</code>) and most other BIFs that take
│ │ │ -a pid or port identifies as an argument.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">register</span><span class="p" data-group-id="5836807821-1">(</span><span class="ss">db</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="5836807821-1">)</span><span class="p">.</span><span class="w">
│ │ │ +a pid or port identifies as an argument.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">register</span><span class="p" data-group-id="9841154292-1">(</span><span class="ss">db</span><span class="p">,</span><span class="w"> </span><span class="n">Pid</span><span class="p" data-group-id="9841154292-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><p>The registered name is considered a
│ │ │  <a href="../../../doc/system/ref_man_processes.html#visible-resources">Directly Visible Erlang Resource</a>
│ │ │  and is automatically unregistered when the process terminates.</p><p>Failures:</p><ul><li><p><strong><code class="inline">badarg</code></strong> - If <code class="inline">PidOrPort</code> is not an existing local process or port.</p></li><li><p><strong><code class="inline">badarg</code></strong> - If <code class="inline">RegName</code> is already in use.</p></li><li><p><strong><code class="inline">badarg</code></strong> - If the process or port is already registered (already has a
│ │ │  name).</p></li><li><p><strong><code class="inline">badarg</code></strong> - If <code class="inline">RegName</code> is the atom <code class="inline">undefined</code>.</p></li></ul>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="registered/0">
│ │ │ @@ -14427,16 +14427,16 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> registered() -> [RegName] when RegName :: <a href="#t:atom/0">atom</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns a list of names that have been registered using <a href="#register/2"><code class="inline">register/2</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">registered</span><span class="p" data-group-id="9884069813-1">(</span><span class="p" data-group-id="9884069813-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9884069813-2">[</span><span class="ss">code_server</span><span class="p">,</span><span class="w"> </span><span class="ss">file_server</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="ss">user</span><span class="p">,</span><span class="w"> </span><span class="ss">my_db</span><span class="p" data-group-id="9884069813-2">]</span></code></pre>
│ │ │ +<p>Returns a list of names that have been registered using <a href="#register/2"><code class="inline">register/2</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">registered</span><span class="p" data-group-id="5286163553-1">(</span><span class="p" data-group-id="5286163553-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="5286163553-2">[</span><span class="ss">code_server</span><span class="p">,</span><span class="w"> </span><span class="ss">file_server</span><span class="p">,</span><span class="w"> </span><span class="ss">init</span><span class="p">,</span><span class="w"> </span><span class="ss">user</span><span class="p">,</span><span class="w"> </span><span class="ss">my_db</span><span class="p" data-group-id="5286163553-2">]</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="resume_process/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#resume_process/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │        <i class="ri-link-m" aria-hidden="true"></i>
│ │ │ @@ -14491,15 +14491,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> self() -> <a href="#t:pid/0">pid</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns the process identifier of the calling process.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">self</span><span class="p" data-group-id="5336197756-1">(</span><span class="p" data-group-id="5336197756-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Returns the process identifier of the calling process.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">self</span><span class="p" data-group-id="2870863501-1">(</span><span class="p" data-group-id="2870863501-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.26</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="send/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#send/2" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -14741,15 +14741,15 @@
│ │ │  <p>Returns the process identifier of a new process started by the application of
│ │ │  <code class="inline">Module:Function</code> to <code class="inline">Args</code>.</p><p><a href="../../../lib/kernel-10.2.7.2/doc/html/error_handler.html"><code class="inline">error_handler:undefined_function(Module, Function, Args)</code></a> is
│ │ │   evaluated by the new process if <code class="inline">Module:Function/Arity</code> does not exist
│ │ │  (where <code class="inline">Arity</code> is the length of <code class="inline">Args</code>). The error handler can be redefined
│ │ │  (see <a href="#process_flag/2"><code class="inline">process_flag/2</code></a>). If
│ │ │  <code class="inline">error_handler</code> is undefined, or the user has redefined the default
│ │ │  <code class="inline">error_handler</code> and its replacement is undefined, a failure with reason <code class="inline">undef</code>
│ │ │ -occurs.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">spawn</span><span class="p" data-group-id="7702748537-1">(</span><span class="ss">speed</span><span class="p">,</span><span class="w"> </span><span class="ss">regulator</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7702748537-2">[</span><span class="ss">high_speed</span><span class="p">,</span><span class="w"> </span><span class="ss">thin_cut</span><span class="p" data-group-id="7702748537-2">]</span><span class="p" data-group-id="7702748537-1">)</span><span class="p">.</span><span class="w">
│ │ │ +occurs.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">spawn</span><span class="p" data-group-id="7151478102-1">(</span><span class="ss">speed</span><span class="p">,</span><span class="w"> </span><span class="ss">regulator</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7151478102-2">[</span><span class="ss">high_speed</span><span class="p">,</span><span class="w"> </span><span class="ss">thin_cut</span><span class="p" data-group-id="7151478102-2">]</span><span class="p" data-group-id="7151478102-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.13</span><span class="p">.</span><span class="mi">1</span><span class="o">&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="spawn/4">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#spawn/4" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -15689,22 +15689,22 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> throw(Any) -> <a href="#t:no_return/0">no_return</a>() when Any :: <a href="#t:term/0">term</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Raises an exception of class <code class="inline">throw</code>. Intended to be used to do non-local
│ │ │  returns from functions.</p><p>If evaluated within a <a href="../../../doc/system/expressions.html#catch-and-throw">catch expression</a>, the
│ │ │ -catch expression returns value <code class="inline">Any</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="5637090366-1">(</span><span class="p" data-group-id="5637090366-2">{</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">there</span><span class="p" data-group-id="5637090366-2">}</span><span class="p" data-group-id="5637090366-1">)</span><span class="p">.</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="5637090366-3">{</span><span class="ss">hello</span><span class="p">,</span><span class="ss">there</span><span class="p" data-group-id="5637090366-3">}</span></code></pre><p>If evaluated within a <code class="inline">try</code>-block of a
│ │ │ +catch expression returns value <code class="inline">Any</code>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="k">catch</span><span class="w"> </span><span class="nf">throw</span><span class="p" data-group-id="0612607283-1">(</span><span class="p" data-group-id="0612607283-2">{</span><span class="ss">hello</span><span class="p">,</span><span class="w"> </span><span class="ss">there</span><span class="p" data-group-id="0612607283-2">}</span><span class="p" data-group-id="0612607283-1">)</span><span class="p">.</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="0612607283-3">{</span><span class="ss">hello</span><span class="p">,</span><span class="ss">there</span><span class="p" data-group-id="0612607283-3">}</span></code></pre><p>If evaluated within a <code class="inline">try</code>-block of a
│ │ │  <a href="../../../doc/system/expressions.html#try">try expression</a>, the value <code class="inline">Any</code> can be caught
│ │ │  within the catch block.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="k">try</span><span class="w">
│ │ │ -    </span><span class="nf">throw</span><span class="p" data-group-id="3874209512-1">(</span><span class="p" data-group-id="3874209512-2">{</span><span class="ss">my_exception</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Something happened&quot;</span><span class="p" data-group-id="3874209512-2">}</span><span class="p" data-group-id="3874209512-1">)</span><span class="w">
│ │ │ +    </span><span class="nf">throw</span><span class="p" data-group-id="1320344335-1">(</span><span class="p" data-group-id="1320344335-2">{</span><span class="ss">my_exception</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Something happened&quot;</span><span class="p" data-group-id="1320344335-2">}</span><span class="p" data-group-id="1320344335-1">)</span><span class="w">
│ │ │  </span><span class="k">catch</span><span class="w">
│ │ │ -    </span><span class="nc">throw</span><span class="p">:</span><span class="p" data-group-id="3874209512-3">{</span><span class="ss">my_exception</span><span class="p">,</span><span class="w"> </span><span class="n">Desc</span><span class="p" data-group-id="3874209512-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="3874209512-4">(</span><span class="ss">standard_error</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Error: </span><span class="si">~s</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3874209512-5">[</span><span class="n">Desc</span><span class="p" data-group-id="3874209512-5">]</span><span class="p" data-group-id="3874209512-4">)</span><span class="w">
│ │ │ +    </span><span class="nc">throw</span><span class="p">:</span><span class="p" data-group-id="1320344335-3">{</span><span class="ss">my_exception</span><span class="p">,</span><span class="w"> </span><span class="n">Desc</span><span class="p" data-group-id="1320344335-3">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="nc">io</span><span class="p">:</span><span class="nf">format</span><span class="p" data-group-id="1320344335-4">(</span><span class="ss">standard_error</span><span class="p">,</span><span class="w"> </span><span class="s">&quot;Error: </span><span class="si">~s</span><span class="si">~n</span><span class="s">&quot;</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1320344335-5">[</span><span class="n">Desc</span><span class="p" data-group-id="1320344335-5">]</span><span class="p" data-group-id="1320344335-4">)</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>Failure: <code class="inline">nocatch</code> if not caught by an exception handler.</p><p>See the guide about <a href="../../../doc/system/errors.html">errors and error handling</a> for
│ │ │  additional information.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="unalias/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -15774,17 +15774,17 @@
│ │ │  <a href="#process_flag_trap_exit">trapping exits</a>, an
│ │ │  <code class="inline">{'EXIT', Id, ExitReason}</code> message due to the link may have been placed in the
│ │ │  message queue of the caller before the <a href="#unlink/1"><code class="inline">unlink(Id)</code></a> call
│ │ │  completed. Also note that the <code class="inline">{'EXIT', Id, ExitReason}</code> message may be the
│ │ │  result of the link, but may also be the result of the unlikee sending the caller
│ │ │  an exit signal by calling the <a href="#exit/2"><code class="inline">exit/2</code></a> BIF. Therefore, it may or may not be
│ │ │  appropriate to clean up the message queue after a call to
│ │ │ -<a href="#unlink/1"><code class="inline">unlink(Id)</code></a> as follows, when trapping exits:</p><pre><code class="makeup erlang" translate="no"><span class="nf">unlink</span><span class="p" data-group-id="8322756209-1">(</span><span class="n">Id</span><span class="p" data-group-id="8322756209-1">)</span><span class="p">,</span><span class="w">
│ │ │ +<a href="#unlink/1"><code class="inline">unlink(Id)</code></a> as follows, when trapping exits:</p><pre><code class="makeup erlang" translate="no"><span class="nf">unlink</span><span class="p" data-group-id="6044695589-1">(</span><span class="n">Id</span><span class="p" data-group-id="6044695589-1">)</span><span class="p">,</span><span class="w">
│ │ │  </span><span class="k">receive</span><span class="w">
│ │ │ -    </span><span class="p" data-group-id="8322756209-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Id</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="8322756209-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +    </span><span class="p" data-group-id="6044695589-2">{</span><span class="ss">&#39;EXIT&#39;</span><span class="p">,</span><span class="w"> </span><span class="n">Id</span><span class="p">,</span><span class="w"> </span><span class="p">_</span><span class="p" data-group-id="6044695589-2">}</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w">
│ │ │  </span><span class="k">after</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │          </span><span class="ss">true</span><span class="w">
│ │ │  </span><span class="k">end</span></code></pre><p>The link removal is performed asynchronously. If such a link does not exist,
│ │ │  nothing is done. A detailed description of the
│ │ │  <a href="erl_dist_protocol.html#link_protocol">link protocol</a> can be found in the
│ │ │  <em>Distribution Protocol</em> chapter of the <em>ERTS User's Guide</em>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>For some important information about distributed signals, see the
│ │ │ @@ -15815,15 +15815,15 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> unregister(RegName) -> true when RegName :: <a href="#t:atom/0">atom</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Removes the <a href="#register/2"><code class="inline">registered name</code></a> <code class="inline">RegName</code> associated with a
│ │ │  process identifier or a port identifier from the
│ │ │ -<a href="../../../doc/system/ref_man_processes.html#runtime-service"><code class="inline">name registry</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">unregister</span><span class="p" data-group-id="4233502535-1">(</span><span class="ss">db</span><span class="p" data-group-id="4233502535-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<a href="../../../doc/system/ref_man_processes.html#runtime-service"><code class="inline">name registry</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">unregister</span><span class="p" data-group-id="6450416177-1">(</span><span class="ss">db</span><span class="p" data-group-id="6450416177-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">true</span></code></pre><p>Keep in mind that you can still receive signals associated with the registered
│ │ │  name after it has been unregistered as the sender may have looked up the name
│ │ │  before sending to it.</p><p>Users are advised not to unregister system processes.</p><p>Failure: <code class="inline">badarg</code> if <code class="inline">RegName</code> is not a registered name.</p>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="whereis/1">
│ │ │  
│ │ │ @@ -15849,15 +15849,15 @@
│ │ │            <pre translate="no"><span class="attribute">-spec</span> whereis(RegName) -> <a href="#t:pid/0">pid</a>() | <a href="#t:port/0">port</a>() | undefined when RegName :: <a href="#t:atom/0">atom</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │  <p>Returns the process identifier or port identifier with the
│ │ │  <a href="#register/2"><code class="inline">registered name</code></a> <code class="inline">RegName</code> from the
│ │ │  <a href="../../../doc/system/ref_man_processes.html#runtime-service"><code class="inline">name registry</code></a>. Returns
│ │ │ -<code class="inline">undefined</code> if the name is not registered.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">whereis</span><span class="p" data-group-id="0780803220-1">(</span><span class="ss">db</span><span class="p" data-group-id="0780803220-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">undefined</code> if the name is not registered.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">whereis</span><span class="p" data-group-id="9536398246-1">(</span><span class="ss">db</span><span class="p" data-group-id="9536398246-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="o">&lt;</span><span class="mf">0.43</span><span class="p">.</span><span class="mi">0</span><span class="o">&gt;</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="yield/0">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#yield/0" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -15924,15 +15924,15 @@
│ │ │  
│ │ │        <div class="specs">
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> halt() -> <a href="#t:no_return/0">no_return</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Equivalent to calling <a href="#halt/2"><code class="inline">halt(0, [])</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">halt</span><span class="p" data-group-id="4653546647-1">(</span><span class="p" data-group-id="4653546647-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Equivalent to calling <a href="#halt/2"><code class="inline">halt(0, [])</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">halt</span><span class="p" data-group-id="8439829173-1">(</span><span class="p" data-group-id="8439829173-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">os_prompt</span><span class="c1">%</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="halt/1">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │      <a href="#halt/1" class="detail-link" data-no-tooltip aria-label="Link to this function">
│ │ │ @@ -15955,15 +15955,15 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> halt(Status :: <a href="#t:non_neg_integer/0">non_neg_integer</a>()) -> <a href="#t:no_return/0">no_return</a>();
│ │ │            (Abort :: abort) -> <a href="#t:no_return/0">no_return</a>();
│ │ │            (CrashDumpSlogan :: <a href="#t:string/0">string</a>()) -> <a href="#t:no_return/0">no_return</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Equivalent to calling <a href="#halt/2"><code class="inline">halt(HaltType, [])</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">halt</span><span class="p" data-group-id="4608926561-1">(</span><span class="mi">17</span><span class="p" data-group-id="4608926561-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<p>Equivalent to calling <a href="#halt/2"><code class="inline">halt(HaltType, [])</code></a>.</p><p>For example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">halt</span><span class="p" data-group-id="9043909327-1">(</span><span class="mi">17</span><span class="p" data-group-id="9043909327-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">os_prompt</span><span class="c1">% echo $?</span><span class="w">
│ │ │  </span><span class="mi">17</span><span class="w">
│ │ │  </span><span class="ss">os_prompt</span><span class="c1">%</span></code></pre>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="halt/2">
│ │ │  
│ │ │ @@ -15990,15 +15990,15 @@
│ │ │  
│ │ │            <pre translate="no"><span class="attribute">-spec</span> halt(Status :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(), Options :: <a href="#t:halt_options/0">halt_options</a>()) -> <a href="#t:no_return/0">no_return</a>();
│ │ │            (Abort :: abort, Options :: <a href="#t:halt_options/0">halt_options</a>()) -> <a href="#t:no_return/0">no_return</a>();
│ │ │            (CrashDumpSlogan :: <a href="#t:string/0">string</a>(), Options :: <a href="#t:halt_options/0">halt_options</a>()) -> <a href="#t:no_return/0">no_return</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Halt the runtime system.</p><ul><li><pre id="halt_status_2"><code class="makeup erlang" translate="no"><span class="nf">halt</span><span class="p" data-group-id="6651161779-1">(</span><span class="n">Status</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6651161779-2">(</span><span class="p" data-group-id="6651161779-2">)</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">halt_options</span><span class="p" data-group-id="6651161779-3">(</span><span class="p" data-group-id="6651161779-3">)</span><span class="p" data-group-id="6651161779-1">)</span></code></pre><p>Halt the runtime system with status code <code class="inline">Status</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>On many platforms, the OS supports only status codes 0-255. A too large
│ │ │ +<p>Halt the runtime system.</p><ul><li><pre id="halt_status_2"><code class="makeup erlang" translate="no"><span class="nf">halt</span><span class="p" data-group-id="1703815589-1">(</span><span class="n">Status</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1703815589-2">(</span><span class="p" data-group-id="1703815589-2">)</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">halt_options</span><span class="p" data-group-id="1703815589-3">(</span><span class="p" data-group-id="1703815589-3">)</span><span class="p" data-group-id="1703815589-1">)</span></code></pre><p>Halt the runtime system with status code <code class="inline">Status</code>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>On many platforms, the OS supports only status codes 0-255. A too large
│ │ │  status code is truncated by clearing the high bits.</p></section><p>Currently the following options are valid:</p><ul><li><p><strong><code class="inline" id="halt_flush">{flush, EnableFlushing}</code></strong> - If <code class="inline">EnableFlushing</code> equals
│ │ │  <code class="inline">true</code>, which also is the default behavior, the runtime system will perform
│ │ │  the following operations before terminating:</p><ul><li>Flush all outstanding output.</li><li>Send all Erlang ports exit signals and wait for them to exit.</li><li>Wait for all async threads to complete all outstanding async jobs.</li><li>Call all installed <a href="erl_nif.html#on_halt">NIF <em>on halt</em> callbacks</a>.</li><li>Wait for all ongoing
│ │ │  <a href="erl_nif.html#delay_halt">NIF calls with the <em>delay halt</em> setting</a> enabled
│ │ │  to return.</li><li>Call all installed <code class="inline">atexit</code>/<code class="inline">on_exit</code> callbacks.</li></ul><p>If <code class="inline">EnableFlushing</code> equals <code class="inline">false</code>, the runtime system will terminate
│ │ │  immediately without performing any of the above listed operations.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Runtime systems prior to OTP 26.0 called all installed <code class="inline">atexit</code>/<code class="inline">on_exit</code>
│ │ │  callbacks also when <code class="inline">flush</code> was disabled, but as of OTP 26.0 this is no
│ │ │ @@ -16007,18 +16007,18 @@
│ │ │  termination of the runtime system. <code class="inline">Timeout</code> is in milliseconds. The default
│ │ │  value is determined by the the <code class="inline">erl</code> <a href="erl_cmd.html#+zhft"><code class="inline">+zhft &lt;Timeout&gt;</code></a>
│ │ │  command line flag.</p><p>If flushing has been ongoing for <code class="inline">Timeout</code> milliseconds, flushing operations
│ │ │  will be interrupted and the runtime system will immediately be terminated
│ │ │  with the exit code <code class="inline">255</code>. If flushing is not enabled, the timeout will have
│ │ │  no effect on the system.</p><p>See also the <code class="inline">erl</code> <a href="erl_cmd.html#+zhft"><code class="inline">+zhft &lt;Timeout&gt;</code></a> command line flag.
│ │ │  Note that the shortest timeout set by the command line flag and the
│ │ │ -<code class="inline">flush_timeout</code> option will be the actual timeout value in effect.</p><p>Since: OTP 27.0</p></li></ul></li><li><pre id="halt_abort_2"><code class="makeup erlang" translate="no"><span class="nf">halt</span><span class="p" data-group-id="2336776536-1">(</span><span class="n">Abort</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">halt_options</span><span class="p" data-group-id="2336776536-2">(</span><span class="p" data-group-id="2336776536-2">)</span><span class="p" data-group-id="2336776536-1">)</span></code></pre><p>Halt the Erlang runtime system by aborting and produce a core dump if core
│ │ │ +<code class="inline">flush_timeout</code> option will be the actual timeout value in effect.</p><p>Since: OTP 27.0</p></li></ul></li><li><pre id="halt_abort_2"><code class="makeup erlang" translate="no"><span class="nf">halt</span><span class="p" data-group-id="4977735570-1">(</span><span class="n">Abort</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">abort</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">halt_options</span><span class="p" data-group-id="4977735570-2">(</span><span class="p" data-group-id="4977735570-2">)</span><span class="p" data-group-id="4977735570-1">)</span></code></pre><p>Halt the Erlang runtime system by aborting and produce a core dump if core
│ │ │  dumping has been enabled in the environment that the runtime system is
│ │ │  executing in.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The <a href="#halt_flush"><code class="inline">{flush, boolean()}</code></a> option will be ignored, and
│ │ │ -flushing will be disabled.</p></section></li><li><pre id="halt_crash_dump_2"><code class="makeup erlang" translate="no"><span class="nf">halt</span><span class="p" data-group-id="9462263256-1">(</span><span class="n">CrashDumpSlogan</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="9462263256-2">(</span><span class="p" data-group-id="9462263256-2">)</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">halt_options</span><span class="p" data-group-id="9462263256-3">(</span><span class="p" data-group-id="9462263256-3">)</span><span class="p" data-group-id="9462263256-1">)</span></code></pre><p>Halt the Erlang runtime system and generate an
│ │ │ +flushing will be disabled.</p></section></li><li><pre id="halt_crash_dump_2"><code class="makeup erlang" translate="no"><span class="nf">halt</span><span class="p" data-group-id="8256338048-1">(</span><span class="n">CrashDumpSlogan</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">string</span><span class="p" data-group-id="8256338048-2">(</span><span class="p" data-group-id="8256338048-2">)</span><span class="p">,</span><span class="w"> </span><span class="n">Options</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">halt_options</span><span class="p" data-group-id="8256338048-3">(</span><span class="p" data-group-id="8256338048-3">)</span><span class="p" data-group-id="8256338048-1">)</span></code></pre><p>Halt the Erlang runtime system and generate an
│ │ │  <a href="crash_dump.html">Erlang crash dump</a>. The string <code class="inline">CrashDumpSlogan</code> will be used
│ │ │  as slogan in the Erlang crash dump created. The slogan will be trunkated if
│ │ │  <code class="inline">CrashDumpSlogan</code> is longer than 1023 characters.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The <a href="#halt_flush"><code class="inline">{flush, boolean()}</code></a> option will be ignored, and
│ │ │  flushing will be disabled.</p></section><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>Behavior changes compared to earlier versions:</p><ul><li>Before OTP 24.2, the slogan was truncated if <code class="inline">CrashDumpSlogan</code> was longer
│ │ │  than 200 characters. Now it will be truncated if longer than 1023
│ │ │  characters.</li><li>Before OTP 20.1, only code points in the range 0-255 were accepted in the
│ │ │  slogan. Now any Unicode string is valid.</li></ul></section></li></ul>
│ │ │ @@ -16195,19 +16195,19 @@
│ │ │                  (wall_clock) -> {Total_Wallclock_Time, Wallclock_Time_Since_Last_Call}
│ │ │                      when
│ │ │                          Total_Wallclock_Time :: <a href="#t:non_neg_integer/0">non_neg_integer</a>(),
│ │ │                          Wallclock_Time_Since_Last_Call :: <a href="#t:non_neg_integer/0">non_neg_integer</a>().</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Returns statistics about the current system.</p><p>The possible flags are:</p><ul><li><pre id="statistics_active_tasks"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1590278269-1">(</span><span class="ss">active_tasks</span><span class="p" data-group-id="1590278269-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1590278269-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1590278269-3">(</span><span class="p" data-group-id="1590278269-3">)</span><span class="p" data-group-id="1590278269-2">]</span></code></pre><p>Returns the same as
│ │ │ +<p>Returns statistics about the current system.</p><p>The possible flags are:</p><ul><li><pre id="statistics_active_tasks"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="8069026751-1">(</span><span class="ss">active_tasks</span><span class="p" data-group-id="8069026751-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8069026751-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="8069026751-3">(</span><span class="p" data-group-id="8069026751-3">)</span><span class="p" data-group-id="8069026751-2">]</span></code></pre><p>Returns the same as
│ │ │  <a href="#statistics_active_tasks_all"><code class="inline">statistics(active_tasks_all)</code></a> with
│ │ │  the exception that no information about the dirty IO run queue and its
│ │ │  associated schedulers is part of the result. That is, only tasks that are
│ │ │ -expected to be CPU bound are part of the result.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_active_tasks_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="3990150715-1">(</span><span class="ss">active_tasks_all</span><span class="p" data-group-id="3990150715-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3990150715-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="3990150715-3">(</span><span class="p" data-group-id="3990150715-3">)</span><span class="p" data-group-id="3990150715-2">]</span></code></pre><p>Returns a list where each element represents the amount of active processes and
│ │ │ +expected to be CPU bound are part of the result.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_active_tasks_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="3091163978-1">(</span><span class="ss">active_tasks_all</span><span class="p" data-group-id="3091163978-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="3091163978-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="3091163978-3">(</span><span class="p" data-group-id="3091163978-3">)</span><span class="p" data-group-id="3091163978-2">]</span></code></pre><p>Returns a list where each element represents the amount of active processes and
│ │ │  ports on each run queue and its associated schedulers. That is, the number of
│ │ │  processes and ports that are ready to run, or are currently running. Values for
│ │ │  normal run queues and their associated schedulers are located first in the
│ │ │  resulting list. The first element corresponds to scheduler number 1 and so on.
│ │ │  If support for dirty schedulers exist, an element with the value for the dirty
│ │ │  CPU run queue and its associated dirty CPU schedulers follow and then as last
│ │ │  element the value for the dirty IO run queue and its associated dirty IO
│ │ │ @@ -16221,44 +16221,44 @@
│ │ │  migrate to other normal run queues. This has to be taken into account when
│ │ │  evaluating the result.</p></section><p>See also
│ │ │  <a href="#statistics_total_active_tasks"><code class="inline">statistics(total_active_tasks)</code></a>,
│ │ │  <a href="#statistics_run_queue_lengths"><code class="inline">statistics(run_queue_lengths)</code></a>,
│ │ │  <a href="#statistics_run_queue_lengths_all"><code class="inline">statistics(run_queue_lengths_all)</code></a>,
│ │ │  <a href="#statistics_total_run_queue_lengths"><code class="inline">statistics(total_run_queue_lengths)</code></a>,
│ │ │  and
│ │ │ -<a href="#statistics_total_run_queue_lengths_all"><code class="inline">statistics(total_run_queue_lengths_all)</code></a>.</p><p>Available since OTP 20.0</p></li><li><pre id="statistics_context_switches"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="8399538531-1">(</span><span class="ss">context_switches</span><span class="p" data-group-id="8399538531-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8399538531-2">{</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="8399538531-3">(</span><span class="p" data-group-id="8399538531-3">)</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="8399538531-2">}</span></code></pre><p>Returns the total number of context switches since the system started.</p></li><li><pre id="statistics_exact_reductions"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="4349380459-1">(</span><span class="ss">exact_reductions</span><span class="p" data-group-id="4349380459-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4349380459-2">{</span><span class="n">Total</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4349380459-3">(</span><span class="p" data-group-id="4349380459-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4349380459-4">(</span><span class="p" data-group-id="4349380459-4">)</span><span class="p" data-group-id="4349380459-2">}</span></code></pre><p>Returns the number of exact reductions.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p><a href="#statistics/1"><code class="inline">statistics(exact_reductions)</code></a> is a more expensive operation
│ │ │ -than <a href="#statistics_reductions">statistics(reductions)</a>.</p></section></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="6577642050-1">(</span><span class="ss">garbage_collection</span><span class="p" data-group-id="6577642050-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="6577642050-2">{</span><span class="w"> </span><span class="n">NumerOfGCs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6577642050-3">(</span><span class="p" data-group-id="6577642050-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">WordsReclaimed</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6577642050-4">(</span><span class="p" data-group-id="6577642050-4">)</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="6577642050-2">}</span></code></pre><p>Returns information about garbage collection, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">statistics</span><span class="p" data-group-id="6753837303-1">(</span><span class="ss">garbage_collection</span><span class="p" data-group-id="6753837303-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="6753837303-2">{</span><span class="mi">85</span><span class="p">,</span><span class="mi">23961</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="6753837303-2">}</span></code></pre><p>This information can be invalid for some implementations.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="6895201792-1">(</span><span class="ss">io</span><span class="p" data-group-id="6895201792-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6895201792-2">{</span><span class="p" data-group-id="6895201792-3">{</span><span class="ss">input</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6895201792-4">(</span><span class="p" data-group-id="6895201792-4">)</span><span class="p" data-group-id="6895201792-3">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="6895201792-5">{</span><span class="ss">output</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6895201792-6">(</span><span class="p" data-group-id="6895201792-6">)</span><span class="p" data-group-id="6895201792-5">}</span><span class="p" data-group-id="6895201792-2">}</span></code></pre><p>Returns <code class="inline">Input</code>, which is the total number of bytes received through ports, and
│ │ │ -<code class="inline">Output</code>, which is the total number of bytes output to ports.</p></li><li><pre id="statistics_microstate_accounting"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="4247341678-1">(</span><span class="ss">microstate_accounting</span><span class="p" data-group-id="4247341678-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4247341678-2">[</span><span class="n">MSAcc_Thread</span><span class="p" data-group-id="4247341678-2">]</span></code></pre><p>Microstate accounting can be used to measure how much time the Erlang runtime
│ │ │ +<a href="#statistics_total_run_queue_lengths_all"><code class="inline">statistics(total_run_queue_lengths_all)</code></a>.</p><p>Available since OTP 20.0</p></li><li><pre id="statistics_context_switches"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1622891127-1">(</span><span class="ss">context_switches</span><span class="p" data-group-id="1622891127-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1622891127-2">{</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1622891127-3">(</span><span class="p" data-group-id="1622891127-3">)</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="1622891127-2">}</span></code></pre><p>Returns the total number of context switches since the system started.</p></li><li><pre id="statistics_exact_reductions"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="6786447714-1">(</span><span class="ss">exact_reductions</span><span class="p" data-group-id="6786447714-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6786447714-2">{</span><span class="n">Total</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6786447714-3">(</span><span class="p" data-group-id="6786447714-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6786447714-4">(</span><span class="p" data-group-id="6786447714-4">)</span><span class="p" data-group-id="6786447714-2">}</span></code></pre><p>Returns the number of exact reductions.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p><a href="#statistics/1"><code class="inline">statistics(exact_reductions)</code></a> is a more expensive operation
│ │ │ +than <a href="#statistics_reductions">statistics(reductions)</a>.</p></section></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="2801663853-1">(</span><span class="ss">garbage_collection</span><span class="p" data-group-id="2801663853-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="2801663853-2">{</span><span class="w"> </span><span class="n">NumerOfGCs</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="2801663853-3">(</span><span class="p" data-group-id="2801663853-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">WordsReclaimed</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="2801663853-4">(</span><span class="p" data-group-id="2801663853-4">)</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="2801663853-2">}</span></code></pre><p>Returns information about garbage collection, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">statistics</span><span class="p" data-group-id="8363674269-1">(</span><span class="ss">garbage_collection</span><span class="p" data-group-id="8363674269-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8363674269-2">{</span><span class="mi">85</span><span class="p">,</span><span class="mi">23961</span><span class="p">,</span><span class="mi">0</span><span class="p" data-group-id="8363674269-2">}</span></code></pre><p>This information can be invalid for some implementations.</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="7625735007-1">(</span><span class="ss">io</span><span class="p" data-group-id="7625735007-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7625735007-2">{</span><span class="p" data-group-id="7625735007-3">{</span><span class="ss">input</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="7625735007-4">(</span><span class="p" data-group-id="7625735007-4">)</span><span class="p" data-group-id="7625735007-3">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="7625735007-5">{</span><span class="ss">output</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="7625735007-6">(</span><span class="p" data-group-id="7625735007-6">)</span><span class="p" data-group-id="7625735007-5">}</span><span class="p" data-group-id="7625735007-2">}</span></code></pre><p>Returns <code class="inline">Input</code>, which is the total number of bytes received through ports, and
│ │ │ +<code class="inline">Output</code>, which is the total number of bytes output to ports.</p></li><li><pre id="statistics_microstate_accounting"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="8849422059-1">(</span><span class="ss">microstate_accounting</span><span class="p" data-group-id="8849422059-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="8849422059-2">[</span><span class="n">MSAcc_Thread</span><span class="p" data-group-id="8849422059-2">]</span></code></pre><p>Microstate accounting can be used to measure how much time the Erlang runtime
│ │ │  system spends doing various tasks. It is designed to be as lightweight as
│ │ │  possible, but some overhead exists when this is enabled. Microstate accounting
│ │ │  is meant to be a profiling tool to help finding performance bottlenecks. To
│ │ │  <code class="inline">start</code>/<code class="inline">stop</code>/<code class="inline">reset</code> microstate accounting, use system flag
│ │ │  <a href="#system_flag_microstate_accounting"><code class="inline">microstate_accounting</code></a>.</p><p><a href="#statistics/1"><code class="inline">statistics(microstate_accounting)</code></a> returns a list of maps
│ │ │  representing some of the OS threads within ERTS. Each map contains <code class="inline">type</code> and
│ │ │  <code class="inline">id</code> fields that can be used to identify what thread it is, and also a counters
│ │ │  field that contains data about how much time has been spent in the various
│ │ │ -states.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="4252536013-1">(</span><span class="ss">microstate_accounting</span><span class="p" data-group-id="4252536013-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="4252536013-2">[</span><span class="p" data-group-id="4252536013-3">#{</span><span class="ss">counters</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="4252536013-4">#{</span><span class="ss">aux</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1899182914</span><span class="p">,</span><span class="w">
│ │ │ +states.</p><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="7307782301-1">(</span><span class="ss">microstate_accounting</span><span class="p" data-group-id="7307782301-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="7307782301-2">[</span><span class="p" data-group-id="7307782301-3">#{</span><span class="ss">counters</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="p" data-group-id="7307782301-4">#{</span><span class="ss">aux</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1899182914</span><span class="p">,</span><span class="w">
│ │ │                   </span><span class="ss">check_io</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">2605863602</span><span class="p">,</span><span class="w">
│ │ │                   </span><span class="ss">emulator</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">45731880463</span><span class="p">,</span><span class="w">
│ │ │                   </span><span class="ss">gc</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1512206910</span><span class="p">,</span><span class="w">
│ │ │                   </span><span class="ss">other</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">5421338456</span><span class="p">,</span><span class="w">
│ │ │                   </span><span class="ss">port</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">221631</span><span class="p">,</span><span class="w">
│ │ │ -                 </span><span class="ss">sleep</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">5150294100</span><span class="p" data-group-id="4252536013-4">}</span><span class="p">,</span><span class="w">
│ │ │ +                 </span><span class="ss">sleep</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">5150294100</span><span class="p" data-group-id="7307782301-4">}</span><span class="p">,</span><span class="w">
│ │ │     </span><span class="ss">id</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w">
│ │ │ -   </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">scheduler</span><span class="p" data-group-id="4252536013-3">}</span><span class="p">|</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="4252536013-2">]</span></code></pre><p>The time unit is the same as returned by <a href="../../../lib/kernel-10.2.7.2/doc/html/os.html#perf_counter/0"><code class="inline">os:perf_counter/0</code></a>. So, to convert it
│ │ │ -to milliseconds, you can do something like this:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="9394615556-1">(</span><span class="w">
│ │ │ -  </span><span class="nf">fun</span><span class="p" data-group-id="9394615556-2">(</span><span class="p" data-group-id="9394615556-3">#{</span><span class="w"> </span><span class="ss">counters</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Cnt</span><span class="w"> </span><span class="p" data-group-id="9394615556-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p" data-group-id="9394615556-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -         </span><span class="n">MsCnt</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="9394615556-4">(</span><span class="nf">fun</span><span class="p" data-group-id="9394615556-5">(</span><span class="p">_</span><span class="n">K</span><span class="p">,</span><span class="w"> </span><span class="n">PerfCount</span><span class="p" data-group-id="9394615556-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -                                    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">convert_time_unit</span><span class="p" data-group-id="9394615556-6">(</span><span class="n">PerfCount</span><span class="p">,</span><span class="w"> </span><span class="ss">perf_counter</span><span class="p">,</span><span class="w"> </span><span class="mi">1000</span><span class="p" data-group-id="9394615556-6">)</span><span class="w">
│ │ │ -                           </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Cnt</span><span class="p" data-group-id="9394615556-4">)</span><span class="p">,</span><span class="w">
│ │ │ -         </span><span class="n">M</span><span class="p" data-group-id="9394615556-7">#{</span><span class="w"> </span><span class="ss">counters</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">MsCnt</span><span class="w"> </span><span class="p" data-group-id="9394615556-7">}</span><span class="w">
│ │ │ -  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="9394615556-8">(</span><span class="ss">microstate_accounting</span><span class="p" data-group-id="9394615556-8">)</span><span class="p" data-group-id="9394615556-1">)</span><span class="p">.</span></code></pre><p>Notice that these values are not guaranteed to be the exact time spent in each
│ │ │ +   </span><span class="ss">type</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"> </span><span class="ss">scheduler</span><span class="p" data-group-id="7307782301-3">}</span><span class="p">|</span><span class="p">.</span><span class="p">.</span><span class="p">.</span><span class="p" data-group-id="7307782301-2">]</span></code></pre><p>The time unit is the same as returned by <a href="../../../lib/kernel-10.2.7.2/doc/html/os.html#perf_counter/0"><code class="inline">os:perf_counter/0</code></a>. So, to convert it
│ │ │ +to milliseconds, you can do something like this:</p><pre><code class="makeup erlang" translate="no"><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="0058076601-1">(</span><span class="w">
│ │ │ +  </span><span class="nf">fun</span><span class="p" data-group-id="0058076601-2">(</span><span class="p" data-group-id="0058076601-3">#{</span><span class="w"> </span><span class="ss">counters</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">Cnt</span><span class="w"> </span><span class="p" data-group-id="0058076601-3">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">M</span><span class="p" data-group-id="0058076601-2">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +         </span><span class="n">MsCnt</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">maps</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="0058076601-4">(</span><span class="nf">fun</span><span class="p" data-group-id="0058076601-5">(</span><span class="p">_</span><span class="n">K</span><span class="p">,</span><span class="w"> </span><span class="n">PerfCount</span><span class="p" data-group-id="0058076601-5">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +                                    </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">convert_time_unit</span><span class="p" data-group-id="0058076601-6">(</span><span class="n">PerfCount</span><span class="p">,</span><span class="w"> </span><span class="ss">perf_counter</span><span class="p">,</span><span class="w"> </span><span class="mi">1000</span><span class="p" data-group-id="0058076601-6">)</span><span class="w">
│ │ │ +                           </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="n">Cnt</span><span class="p" data-group-id="0058076601-4">)</span><span class="p">,</span><span class="w">
│ │ │ +         </span><span class="n">M</span><span class="p" data-group-id="0058076601-7">#{</span><span class="w"> </span><span class="ss">counters</span><span class="w"> </span><span class="p">:=</span><span class="w"> </span><span class="n">MsCnt</span><span class="w"> </span><span class="p" data-group-id="0058076601-7">}</span><span class="w">
│ │ │ +  </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="0058076601-8">(</span><span class="ss">microstate_accounting</span><span class="p" data-group-id="0058076601-8">)</span><span class="p" data-group-id="0058076601-1">)</span><span class="p">.</span></code></pre><p>Notice that these values are not guaranteed to be the exact time spent in each
│ │ │  state. This is because of various optimisation done to keep the overhead as
│ │ │  small as possible.</p><p><code class="inline">MSAcc_Thread_Type</code>s:</p><ul><li><p><strong><code class="inline">scheduler</code></strong> - The main execution threads that do most of the work. See
│ │ │  <a href="erl_cmd.html#%2BS">erl +S</a> for more details.</p></li><li><p><strong><code class="inline">dirty_cpu_scheduler</code></strong> - The threads for long running cpu intensive work.
│ │ │  See <a href="erl_cmd.html#%2BSDcpu">erl +SDcpu</a> for more details.</p></li><li><p><strong><code class="inline">dirty_io_scheduler</code></strong> - The threads for long running I/O work. See
│ │ │  <a href="erl_cmd.html#%2BSDio">erl +SDio</a> for more details.</p></li><li><p><strong><code class="inline">async</code></strong> - Async threads are used by various linked-in drivers (mainly the
│ │ │  file drivers) do offload non-CPU intensive work. See
│ │ │  <a href="erl_cmd.html#async_thread_pool_size">erl +A</a> for more details.</p></li><li><p><strong><code class="inline">aux</code></strong> - Takes care of any work that is not specifically assigned to a
│ │ │ @@ -16282,28 +16282,28 @@
│ │ │  states this time is part of the <code class="inline">gc</code> state.</p></li><li><p><strong><code class="inline">nif</code></strong> - Time spent in NIFs. Without extra states this time is part of the
│ │ │  <code class="inline">emulator</code> state.</p></li><li><p><strong><code class="inline">send</code></strong> - Time spent sending messages (processes only). Without extra
│ │ │  states this time is part of the <code class="inline">emulator</code> state.</p></li><li><p><strong><code class="inline">timers</code></strong> - Time spent managing timers. Without extra states this time is
│ │ │  part of the <code class="inline">other</code> state.</p></li></ul><p>The utility module <a href="../../../lib/runtime_tools-2.1.1/doc/html/msacc.html"><code class="inline">msacc</code></a> can be used to more easily analyse these
│ │ │  statistics.</p><p>Returns <code class="inline">undefined</code> if system flag
│ │ │  <a href="#system_flag_microstate_accounting"><code class="inline">microstate_accounting</code></a> is
│ │ │  turned off.</p><p>The list of thread information is unsorted and can appear in different order
│ │ │ -between calls.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The threads and states are subject to change without any prior notice.</p></section><p>Available since OTP 19.0</p></li><li><pre id="statistics_reductions"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1281505113-1">(</span><span class="ss">reductions</span><span class="p" data-group-id="1281505113-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1281505113-2">{</span><span class="n">Reductions</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1281505113-3">(</span><span class="p" data-group-id="1281505113-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1281505113-4">(</span><span class="p" data-group-id="1281505113-4">)</span><span class="p" data-group-id="1281505113-2">}</span></code></pre><p>Returns information about reductions, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">statistics</span><span class="p" data-group-id="9643665168-1">(</span><span class="ss">reductions</span><span class="p" data-group-id="9643665168-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="9643665168-2">{</span><span class="mi">2046</span><span class="p">,</span><span class="mi">11</span><span class="p" data-group-id="9643665168-2">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>As from ERTS 5.5 (Erlang/OTP R11B), this value does not include reductions
│ │ │ +between calls.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The threads and states are subject to change without any prior notice.</p></section><p>Available since OTP 19.0</p></li><li><pre id="statistics_reductions"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="4908043088-1">(</span><span class="ss">reductions</span><span class="p" data-group-id="4908043088-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4908043088-2">{</span><span class="n">Reductions</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4908043088-3">(</span><span class="p" data-group-id="4908043088-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4908043088-4">(</span><span class="p" data-group-id="4908043088-4">)</span><span class="p" data-group-id="4908043088-2">}</span></code></pre><p>Returns information about reductions, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">statistics</span><span class="p" data-group-id="9897386132-1">(</span><span class="ss">reductions</span><span class="p" data-group-id="9897386132-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="9897386132-2">{</span><span class="mi">2046</span><span class="p">,</span><span class="mi">11</span><span class="p" data-group-id="9897386132-2">}</span></code></pre><section role="note" class="admonition info"><h4 class="admonition-title info">Change</h4><p>As from ERTS 5.5 (Erlang/OTP R11B), this value does not include reductions
│ │ │  performed in current time slices of currently scheduled processes. If an exact
│ │ │  value is wanted, use
│ │ │ -<a href="#statistics_exact_reductions"><code class="inline">statistics(exact_reductions)</code></a>.</p></section></li><li><pre id="statistics_run_queue"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="3930222018-1">(</span><span class="ss">run_queue</span><span class="p" data-group-id="3930222018-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="3930222018-2">(</span><span class="p" data-group-id="3930222018-2">)</span></code></pre><p>Returns the total length of all normal and dirty CPU run queues. That is, queued
│ │ │ +<a href="#statistics_exact_reductions"><code class="inline">statistics(exact_reductions)</code></a>.</p></section></li><li><pre id="statistics_run_queue"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="0830794962-1">(</span><span class="ss">run_queue</span><span class="p" data-group-id="0830794962-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="0830794962-2">(</span><span class="p" data-group-id="0830794962-2">)</span></code></pre><p>Returns the total length of all normal and dirty CPU run queues. That is, queued
│ │ │  work that is expected to be CPU bound. The information is gathered atomically.
│ │ │  That is, the result is a consistent snapshot of the state, but this operation is
│ │ │  much more expensive compared to
│ │ │  <a href="#statistics_total_run_queue_lengths"><code class="inline">statistics(total_run_queue_lengths)</code></a>,
│ │ │ -especially when a large amount of schedulers is used.</p></li><li><pre id="statistics_run_queue_lengths"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="2354494351-1">(</span><span class="ss">run_queue_lengths</span><span class="p" data-group-id="2354494351-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2354494351-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="2354494351-3">(</span><span class="p" data-group-id="2354494351-3">)</span><span class="p" data-group-id="2354494351-2">]</span></code></pre><p>Returns the same as
│ │ │ +especially when a large amount of schedulers is used.</p></li><li><pre id="statistics_run_queue_lengths"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1618324384-1">(</span><span class="ss">run_queue_lengths</span><span class="p" data-group-id="1618324384-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1618324384-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1618324384-3">(</span><span class="p" data-group-id="1618324384-3">)</span><span class="p" data-group-id="1618324384-2">]</span></code></pre><p>Returns the same as
│ │ │  <a href="#statistics_run_queue_lengths_all"><code class="inline">statistics(run_queue_lengths_all)</code></a>
│ │ │  with the exception that no information about the dirty IO run queue is part of
│ │ │  the result. That is, only run queues with work that is expected to be CPU bound
│ │ │ -is part of the result.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_run_queue_lengths_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="9197906993-1">(</span><span class="ss">run_queue_lengths_all</span><span class="p" data-group-id="9197906993-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="9197906993-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="9197906993-3">(</span><span class="p" data-group-id="9197906993-3">)</span><span class="p" data-group-id="9197906993-2">]</span></code></pre><p>Returns a list where each element represents the amount of processes and ports
│ │ │ +is part of the result.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_run_queue_lengths_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1975850653-1">(</span><span class="ss">run_queue_lengths_all</span><span class="p" data-group-id="1975850653-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="1975850653-2">[</span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1975850653-3">(</span><span class="p" data-group-id="1975850653-3">)</span><span class="p" data-group-id="1975850653-2">]</span></code></pre><p>Returns a list where each element represents the amount of processes and ports
│ │ │  ready to run for each run queue. Values for normal run queues are located first
│ │ │  in the resulting list. The first element corresponds to the normal run queue of
│ │ │  scheduler number 1 and so on. If support for dirty schedulers exist, values for
│ │ │  the dirty CPU run queue and the dirty IO run queue follow (in that order) at the
│ │ │  end. The information is <em>not</em> gathered atomically. That is, the result is not
│ │ │  necessarily a consistent snapshot of the state, but instead quite efficiently
│ │ │  gathered.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Each normal scheduler has one run queue that it manages. If dirty schedulers
│ │ │ @@ -16315,21 +16315,21 @@
│ │ │  evaluating the result.</p></section><p>See also
│ │ │  <a href="#statistics_run_queue_lengths"><code class="inline">statistics(run_queue_lengths)</code></a>,
│ │ │  <a href="#statistics_total_run_queue_lengths_all"><code class="inline">statistics(total_run_queue_lengths_all)</code></a>,
│ │ │  <a href="#statistics_total_run_queue_lengths"><code class="inline">statistics(total_run_queue_lengths)</code></a>,
│ │ │  <a href="#statistics_active_tasks"><code class="inline">statistics(active_tasks)</code></a>,
│ │ │  <a href="#statistics_active_tasks_all"><code class="inline">statistics(active_tasks_all)</code></a>, and
│ │ │  <a href="#statistics_total_active_tasks"><code class="inline">statistics(total_active_tasks)</code></a>,
│ │ │ -<a href="#statistics_total_active_tasks_all"><code class="inline">statistics(total_active_tasks_all)</code></a>.</p><p>Available since OTP 20.0</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="6166856813-1">(</span><span class="ss">runtime</span><span class="p" data-group-id="6166856813-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="6166856813-2">{</span><span class="n">Total</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6166856813-3">(</span><span class="p" data-group-id="6166856813-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="6166856813-4">(</span><span class="p" data-group-id="6166856813-4">)</span><span class="p" data-group-id="6166856813-2">}</span></code></pre><p>Returns information about runtime, in milliseconds.</p><p>This is the sum of the runtime for all threads in the Erlang runtime system and
│ │ │ +<a href="#statistics_total_active_tasks_all"><code class="inline">statistics(total_active_tasks_all)</code></a>.</p><p>Available since OTP 20.0</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="4047224126-1">(</span><span class="ss">runtime</span><span class="p" data-group-id="4047224126-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="4047224126-2">{</span><span class="n">Total</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4047224126-3">(</span><span class="p" data-group-id="4047224126-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4047224126-4">(</span><span class="p" data-group-id="4047224126-4">)</span><span class="p" data-group-id="4047224126-2">}</span></code></pre><p>Returns information about runtime, in milliseconds.</p><p>This is the sum of the runtime for all threads in the Erlang runtime system and
│ │ │  can therefore be greater than the wall clock time.</p><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p>This value might wrap due to limitations in the underlying functionality
│ │ │ -provided by the operating system that is used.</p></section><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">statistics</span><span class="p" data-group-id="2443583021-1">(</span><span class="ss">runtime</span><span class="p" data-group-id="2443583021-1">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="2443583021-2">{</span><span class="mi">1690</span><span class="p">,</span><span class="mi">1620</span><span class="p" data-group-id="2443583021-2">}</span></code></pre></li><li><pre id="statistics_scheduler_wall_time"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="4353130016-1">(</span><span class="ss">scheduler_wall_time</span><span class="p" data-group-id="4353130016-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="4353130016-2">[</span><span class="p" data-group-id="4353130016-3">{</span><span class="n">Id</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">pos_integer</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ActiveTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4353130016-4">(</span><span class="p" data-group-id="4353130016-4">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">TotalTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="4353130016-5">(</span><span class="p" data-group-id="4353130016-5">)</span><span class="p" data-group-id="4353130016-3">}</span><span class="p" data-group-id="4353130016-2">]</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │ +provided by the operating system that is used.</p></section><p>Example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nf">statistics</span><span class="p" data-group-id="8105512030-1">(</span><span class="ss">runtime</span><span class="p" data-group-id="8105512030-1">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="8105512030-2">{</span><span class="mi">1690</span><span class="p">,</span><span class="mi">1620</span><span class="p" data-group-id="8105512030-2">}</span></code></pre></li><li><pre id="statistics_scheduler_wall_time"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1916458824-1">(</span><span class="ss">scheduler_wall_time</span><span class="p" data-group-id="1916458824-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="1916458824-2">[</span><span class="p" data-group-id="1916458824-3">{</span><span class="n">Id</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">pos_integer</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ActiveTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1916458824-4">(</span><span class="p" data-group-id="1916458824-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">TotalTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1916458824-5">(</span><span class="p" data-group-id="1916458824-5">)</span><span class="p" data-group-id="1916458824-3">}</span><span class="p" data-group-id="1916458824-2">]</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │    </span><span class="ss">undefined</span></code></pre><p>Returns information describing how much time
│ │ │  <a href="#system_info_schedulers">normal</a> and
│ │ │  <a href="#system_info_dirty_cpu_schedulers">dirty CPU</a> schedulers in the
│ │ │  system have been busy. This value is normally a better indicator of how much
│ │ │  load an Erlang node is under instead of looking at the CPU utilization provided
│ │ │  by tools such as <code class="inline">top</code> or <code class="inline">sysstat</code>. This is because <code class="inline">scheduler_wall_time</code> also
│ │ │  includes time where the scheduler is waiting for some other reasource (such as
│ │ │ @@ -16361,60 +16361,60 @@
│ │ │  Dirty CPU schedulers will have scheduler identifiers in the range
│ │ │  <code class="inline">erlang:system_info(schedulers) &lt; SchedulerId =&lt; erlang:system_info(schedulers) +</code><a href="#system_info_dirty_cpu_schedulers"><code class="inline">erlang:system_info(dirty_cpu_schedulers)</code></a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>The different types of schedulers handle specific types of jobs. Every job is
│ │ │  assigned to a specific scheduler type. Jobs can migrate between different
│ │ │  schedulers of the same type, but never between schedulers of different types.
│ │ │  This fact has to be taken under consideration when evaluating the result
│ │ │  returned.</p></section><p>You can use <code class="inline">scheduler_wall_time</code> to calculate scheduler utilization. First you
│ │ │  take a sample of the values returned by
│ │ │ -<code class="inline">erlang:statistics(scheduler_wall_time)</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_flag</span><span class="p" data-group-id="3708188802-1">(</span><span class="ss">scheduler_wall_time</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="3708188802-1">)</span><span class="p">.</span><span class="w">
│ │ │ +<code class="inline">erlang:statistics(scheduler_wall_time)</code>.</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_flag</span><span class="p" data-group-id="2744146039-1">(</span><span class="ss">scheduler_wall_time</span><span class="p">,</span><span class="w"> </span><span class="ss">true</span><span class="p" data-group-id="2744146039-1">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">false</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="n">Ts0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="3708188802-2">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="3708188802-3">(</span><span class="ss">scheduler_wall_time</span><span class="p" data-group-id="3708188802-3">)</span><span class="p" data-group-id="3708188802-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ +&gt; </span><span class="n">Ts0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="2744146039-2">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="2744146039-3">(</span><span class="ss">scheduler_wall_time</span><span class="p" data-group-id="2744146039-3">)</span><span class="p" data-group-id="2744146039-2">)</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span></code></pre><p>Some time later the user takes another snapshot and calculates scheduler
│ │ │ -utilization per scheduler, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Ts1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="8624142087-1">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="8624142087-2">(</span><span class="ss">scheduler_wall_time</span><span class="p" data-group-id="8624142087-2">)</span><span class="p" data-group-id="8624142087-1">)</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │ +utilization per scheduler, for example:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">Ts1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">sort</span><span class="p" data-group-id="1252919596-1">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">statistics</span><span class="p" data-group-id="1252919596-2">(</span><span class="ss">scheduler_wall_time</span><span class="p" data-group-id="1252919596-2">)</span><span class="p" data-group-id="1252919596-1">)</span><span class="p">,</span><span class="w"> </span><span class="ss">ok</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="ss">ok</span><span class="gp unselectable">
│ │ │ -&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="8624142087-3">(</span><span class="nf">fun</span><span class="p" data-group-id="8624142087-4">(</span><span class="p" data-group-id="8624142087-5">{</span><span class="p" data-group-id="8624142087-6">{</span><span class="n">I</span><span class="p">,</span><span class="w"> </span><span class="n">A0</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="8624142087-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8624142087-7">{</span><span class="n">I</span><span class="p">,</span><span class="w"> </span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="8624142087-7">}</span><span class="p" data-group-id="8624142087-5">}</span><span class="p" data-group-id="8624142087-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="8624142087-8">{</span><span class="n">I</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="8624142087-9">(</span><span class="n">A1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">A0</span><span class="p" data-group-id="8624142087-9">)</span><span class="o">/</span><span class="p" data-group-id="8624142087-10">(</span><span class="n">T1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="8624142087-10">)</span><span class="p" data-group-id="8624142087-8">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">zip</span><span class="p" data-group-id="8624142087-11">(</span><span class="n">Ts0</span><span class="p">,</span><span class="n">Ts1</span><span class="p" data-group-id="8624142087-11">)</span><span class="p" data-group-id="8624142087-3">)</span><span class="p">.</span><span class="w">
│ │ │ -</span><span class="p" data-group-id="8624142087-12">[</span><span class="p" data-group-id="8624142087-13">{</span><span class="mi">1</span><span class="p">,</span><span class="mf">0.9743474730177548</span><span class="p" data-group-id="8624142087-13">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8624142087-14">{</span><span class="mi">2</span><span class="p">,</span><span class="mf">0.9744843782751444</span><span class="p" data-group-id="8624142087-14">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8624142087-15">{</span><span class="mi">3</span><span class="p">,</span><span class="mf">0.9995902361669045</span><span class="p" data-group-id="8624142087-15">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8624142087-16">{</span><span class="mi">4</span><span class="p">,</span><span class="mf">0.9738012596572161</span><span class="p" data-group-id="8624142087-16">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8624142087-17">{</span><span class="mi">5</span><span class="p">,</span><span class="mf">0.9717956667018103</span><span class="p" data-group-id="8624142087-17">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8624142087-18">{</span><span class="mi">6</span><span class="p">,</span><span class="mf">0.9739235846420741</span><span class="p" data-group-id="8624142087-18">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8624142087-19">{</span><span class="mi">7</span><span class="p">,</span><span class="mf">0.973237033077876</span><span class="p" data-group-id="8624142087-19">}</span><span class="p">,</span><span class="w">
│ │ │ - </span><span class="p" data-group-id="8624142087-20">{</span><span class="mi">8</span><span class="p">,</span><span class="mf">0.9741297293248656</span><span class="p" data-group-id="8624142087-20">}</span><span class="p" data-group-id="8624142087-12">]</span></code></pre><p>Using the same snapshots to calculate a total scheduler utilization:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="4470412785-1">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="4470412785-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="4470412785-2">(</span><span class="nf">fun</span><span class="p" data-group-id="4470412785-3">(</span><span class="p" data-group-id="4470412785-4">{</span><span class="p" data-group-id="4470412785-5">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A0</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="4470412785-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4470412785-6">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="4470412785-6">}</span><span class="p" data-group-id="4470412785-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4470412785-7">{</span><span class="n">Ai</span><span class="p">,</span><span class="n">Ti</span><span class="p" data-group-id="4470412785-7">}</span><span class="p" data-group-id="4470412785-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -        </span><span class="p" data-group-id="4470412785-8">{</span><span class="n">Ai</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="4470412785-9">(</span><span class="n">A1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">A0</span><span class="p" data-group-id="4470412785-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Ti</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="4470412785-10">(</span><span class="n">T1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="4470412785-10">)</span><span class="p" data-group-id="4470412785-8">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="4470412785-11">{</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="4470412785-11">}</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">zip</span><span class="p" data-group-id="4470412785-12">(</span><span class="n">Ts0</span><span class="p">,</span><span class="n">Ts1</span><span class="p" data-group-id="4470412785-12">)</span><span class="p" data-group-id="4470412785-2">)</span><span class="p">,</span><span class="w">
│ │ │ +&gt; </span><span class="nc">lists</span><span class="p">:</span><span class="nf">map</span><span class="p" data-group-id="1252919596-3">(</span><span class="nf">fun</span><span class="p" data-group-id="1252919596-4">(</span><span class="p" data-group-id="1252919596-5">{</span><span class="p" data-group-id="1252919596-6">{</span><span class="n">I</span><span class="p">,</span><span class="w"> </span><span class="n">A0</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="1252919596-6">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1252919596-7">{</span><span class="n">I</span><span class="p">,</span><span class="w"> </span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="1252919596-7">}</span><span class="p" data-group-id="1252919596-5">}</span><span class="p" data-group-id="1252919596-4">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="1252919596-8">{</span><span class="n">I</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="1252919596-9">(</span><span class="n">A1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">A0</span><span class="p" data-group-id="1252919596-9">)</span><span class="o">/</span><span class="p" data-group-id="1252919596-10">(</span><span class="n">T1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="1252919596-10">)</span><span class="p" data-group-id="1252919596-8">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">zip</span><span class="p" data-group-id="1252919596-11">(</span><span class="n">Ts0</span><span class="p">,</span><span class="n">Ts1</span><span class="p" data-group-id="1252919596-11">)</span><span class="p" data-group-id="1252919596-3">)</span><span class="p">.</span><span class="w">
│ │ │ +</span><span class="p" data-group-id="1252919596-12">[</span><span class="p" data-group-id="1252919596-13">{</span><span class="mi">1</span><span class="p">,</span><span class="mf">0.9743474730177548</span><span class="p" data-group-id="1252919596-13">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1252919596-14">{</span><span class="mi">2</span><span class="p">,</span><span class="mf">0.9744843782751444</span><span class="p" data-group-id="1252919596-14">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1252919596-15">{</span><span class="mi">3</span><span class="p">,</span><span class="mf">0.9995902361669045</span><span class="p" data-group-id="1252919596-15">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1252919596-16">{</span><span class="mi">4</span><span class="p">,</span><span class="mf">0.9738012596572161</span><span class="p" data-group-id="1252919596-16">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1252919596-17">{</span><span class="mi">5</span><span class="p">,</span><span class="mf">0.9717956667018103</span><span class="p" data-group-id="1252919596-17">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1252919596-18">{</span><span class="mi">6</span><span class="p">,</span><span class="mf">0.9739235846420741</span><span class="p" data-group-id="1252919596-18">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1252919596-19">{</span><span class="mi">7</span><span class="p">,</span><span class="mf">0.973237033077876</span><span class="p" data-group-id="1252919596-19">}</span><span class="p">,</span><span class="w">
│ │ │ + </span><span class="p" data-group-id="1252919596-20">{</span><span class="mi">8</span><span class="p">,</span><span class="mf">0.9741297293248656</span><span class="p" data-group-id="1252919596-20">}</span><span class="p" data-group-id="1252919596-12">]</span></code></pre><p>Using the same snapshots to calculate a total scheduler utilization:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="p" data-group-id="2163874938-1">{</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="p" data-group-id="2163874938-1">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">foldl</span><span class="p" data-group-id="2163874938-2">(</span><span class="nf">fun</span><span class="p" data-group-id="2163874938-3">(</span><span class="p" data-group-id="2163874938-4">{</span><span class="p" data-group-id="2163874938-5">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A0</span><span class="p">,</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="2163874938-5">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2163874938-6">{</span><span class="p">_</span><span class="p">,</span><span class="w"> </span><span class="n">A1</span><span class="p">,</span><span class="w"> </span><span class="n">T1</span><span class="p" data-group-id="2163874938-6">}</span><span class="p" data-group-id="2163874938-4">}</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2163874938-7">{</span><span class="n">Ai</span><span class="p">,</span><span class="n">Ti</span><span class="p" data-group-id="2163874938-7">}</span><span class="p" data-group-id="2163874938-3">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +        </span><span class="p" data-group-id="2163874938-8">{</span><span class="n">Ai</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="2163874938-9">(</span><span class="n">A1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">A0</span><span class="p" data-group-id="2163874938-9">)</span><span class="p">,</span><span class="w"> </span><span class="n">Ti</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="p" data-group-id="2163874938-10">(</span><span class="n">T1</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">T0</span><span class="p" data-group-id="2163874938-10">)</span><span class="p" data-group-id="2163874938-8">}</span><span class="w"> </span><span class="k">end</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="2163874938-11">{</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p" data-group-id="2163874938-11">}</span><span class="p">,</span><span class="w"> </span><span class="nc">lists</span><span class="p">:</span><span class="nf">zip</span><span class="p" data-group-id="2163874938-12">(</span><span class="n">Ts0</span><span class="p">,</span><span class="n">Ts1</span><span class="p" data-group-id="2163874938-12">)</span><span class="p" data-group-id="2163874938-2">)</span><span class="p">,</span><span class="w">
│ │ │    </span><span class="n">TotalSchedulerUtilization</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">A</span><span class="o">/</span><span class="n">T</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">0.9769136803764825</span></code></pre><p>Total scheduler utilization will equal <code class="inline">1.0</code> when all schedulers have been
│ │ │  active all the time between the two measurements.</p><p>Another (probably more) useful value is to calculate total scheduler utilization
│ │ │ -weighted against maximum amount of available CPU time:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">WeightedSchedulerUtilization</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="1158371236-1">(</span><span class="n">TotalSchedulerUtilization</span><span class="w">
│ │ │ -                                  </span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="1158371236-2">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="1158371236-3">(</span><span class="ss">schedulers</span><span class="p" data-group-id="1158371236-3">)</span><span class="w">
│ │ │ -                                     </span><span class="o">+</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="1158371236-4">(</span><span class="ss">dirty_cpu_schedulers</span><span class="p" data-group-id="1158371236-4">)</span><span class="p" data-group-id="1158371236-2">)</span><span class="p" data-group-id="1158371236-1">)</span><span class="w">
│ │ │ -                                 </span><span class="o">/</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="1158371236-5">(</span><span class="ss">logical_processors_available</span><span class="p" data-group-id="1158371236-5">)</span><span class="p">.</span><span class="w">
│ │ │ +weighted against maximum amount of available CPU time:</p><pre><code class="makeup erlang" translate="no"><span class="gp unselectable">&gt; </span><span class="n">WeightedSchedulerUtilization</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p" data-group-id="6242454908-1">(</span><span class="n">TotalSchedulerUtilization</span><span class="w">
│ │ │ +                                  </span><span class="o">*</span><span class="w"> </span><span class="p" data-group-id="6242454908-2">(</span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="6242454908-3">(</span><span class="ss">schedulers</span><span class="p" data-group-id="6242454908-3">)</span><span class="w">
│ │ │ +                                     </span><span class="o">+</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="6242454908-4">(</span><span class="ss">dirty_cpu_schedulers</span><span class="p" data-group-id="6242454908-4">)</span><span class="p" data-group-id="6242454908-2">)</span><span class="p" data-group-id="6242454908-1">)</span><span class="w">
│ │ │ +                                 </span><span class="o">/</span><span class="w"> </span><span class="nc">erlang</span><span class="p">:</span><span class="nf">system_info</span><span class="p" data-group-id="6242454908-5">(</span><span class="ss">logical_processors_available</span><span class="p" data-group-id="6242454908-5">)</span><span class="p">.</span><span class="w">
│ │ │  </span><span class="mf">0.9769136803764825</span></code></pre><p>This weighted scheduler utilization will reach <code class="inline">1.0</code> when schedulers are active
│ │ │  the same amount of time as maximum available CPU time. If more schedulers exist
│ │ │  than available logical processors, this value may be greater than <code class="inline">1.0</code>.</p><p>As of ERTS version 9.0, the Erlang runtime system will as default have more
│ │ │  schedulers than logical processors. This due to the dirty schedulers.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p><code class="inline">scheduler_wall_time</code> is by default disabled. To enable it, use
│ │ │ -<a href="#system_flag_scheduler_wall_time"><code class="inline">erlang:system_flag(scheduler_wall_time, true)</code></a>.</p></section><p>Available since OTP R15B01</p></li><li><pre id="statistics_scheduler_wall_time_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="9063640250-1">(</span><span class="ss">scheduler_wall_time_all</span><span class="p" data-group-id="9063640250-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ -  </span><span class="p" data-group-id="9063640250-2">[</span><span class="p" data-group-id="9063640250-3">{</span><span class="n">Id</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">pos_integer</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">ActiveTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="9063640250-4">(</span><span class="p" data-group-id="9063640250-4">)</span><span class="p">,</span><span class="w">
│ │ │ -    </span><span class="n">TotalTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="9063640250-5">(</span><span class="p" data-group-id="9063640250-5">)</span><span class="p" data-group-id="9063640250-3">}</span><span class="p" data-group-id="9063640250-2">]</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │ +<a href="#system_flag_scheduler_wall_time"><code class="inline">erlang:system_flag(scheduler_wall_time, true)</code></a>.</p></section><p>Available since OTP R15B01</p></li><li><pre id="statistics_scheduler_wall_time_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="3977848777-1">(</span><span class="ss">scheduler_wall_time_all</span><span class="p" data-group-id="3977848777-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +  </span><span class="p" data-group-id="3977848777-2">[</span><span class="p" data-group-id="3977848777-3">{</span><span class="n">Id</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="ss">pos_integer</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">ActiveTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="3977848777-4">(</span><span class="p" data-group-id="3977848777-4">)</span><span class="p">,</span><span class="w">
│ │ │ +    </span><span class="n">TotalTime</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="3977848777-5">(</span><span class="p" data-group-id="3977848777-5">)</span><span class="p" data-group-id="3977848777-3">}</span><span class="p" data-group-id="3977848777-2">]</span><span class="w"> </span><span class="p">|</span><span class="w">
│ │ │    </span><span class="ss">undefined</span></code></pre><p>Equivalent to
│ │ │  <a href="#statistics_scheduler_wall_time"><code class="inline">statistics(scheduler_wall_time)</code></a>,
│ │ │  except that it also include information about all dirty I/O schedulers.</p><p>Dirty IO schedulers will have scheduler identifiers in the range
│ │ │  <a href="#system_info_schedulers"><code class="inline">erlang:system_info(schedulers)</code></a><code class="inline">+</code><a href="#system_info_dirty_cpu_schedulers"><code class="inline">erlang:system_info(dirty_cpu_schedulers)</code></a><code class="inline">&lt; SchedulerId =&lt; erlang:system_info(schedulers) + erlang:system_info(dirty_cpu_schedulers) +</code><a href="#system_info_dirty_io_schedulers"><code class="inline">erlang:system_info(dirty_io_schedulers)</code></a>.</p><section role="note" class="admonition info"><h4 class="admonition-title info">Note</h4><p>Note that work executing on dirty I/O schedulers are expected to mainly wait
│ │ │  for I/O. That is, when you get high scheduler utilization on dirty I/O
│ │ │ -schedulers, CPU utilization is <em>not</em> expected to be high due to this work.</p></section><p>Available since OTP 20.0</p></li><li><pre id="statistics_total_active_tasks"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="9487764390-1">(</span><span class="ss">total_active_tasks</span><span class="p" data-group-id="9487764390-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="9487764390-2">(</span><span class="p" data-group-id="9487764390-2">)</span></code></pre><p>Equivalent to calling
│ │ │ +schedulers, CPU utilization is <em>not</em> expected to be high due to this work.</p></section><p>Available since OTP 20.0</p></li><li><pre id="statistics_total_active_tasks"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1665493162-1">(</span><span class="ss">total_active_tasks</span><span class="p" data-group-id="1665493162-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1665493162-2">(</span><span class="p" data-group-id="1665493162-2">)</span></code></pre><p>Equivalent to calling
│ │ │  <code class="inline">lists:sum(</code><a href="#statistics_active_tasks"><code class="inline">statistics(active_tasks)</code></a><code class="inline">)</code>,
│ │ │ -but more efficient.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_total_active_tasks_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="8930813938-1">(</span><span class="ss">total_active_tasks_all</span><span class="p" data-group-id="8930813938-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="8930813938-2">(</span><span class="p" data-group-id="8930813938-2">)</span></code></pre><p>Equivalent to calling
│ │ │ +but more efficient.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_total_active_tasks_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="1721020074-1">(</span><span class="ss">total_active_tasks_all</span><span class="p" data-group-id="1721020074-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1721020074-2">(</span><span class="p" data-group-id="1721020074-2">)</span></code></pre><p>Equivalent to calling
│ │ │  <code class="inline">lists:sum(</code><a href="#statistics_active_tasks_all"><code class="inline">statistics(active_tasks_all)</code></a><code class="inline">)</code>,
│ │ │ -but more efficient.</p><p>Available since OTP 20.0</p></li><li><pre id="statistics_total_run_queue_lengths"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="3667537814-1">(</span><span class="ss">total_run_queue_lengths</span><span class="p" data-group-id="3667537814-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="3667537814-2">(</span><span class="p" data-group-id="3667537814-2">)</span></code></pre><p>Equivalent to calling
│ │ │ +but more efficient.</p><p>Available since OTP 20.0</p></li><li><pre id="statistics_total_run_queue_lengths"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="7091723392-1">(</span><span class="ss">total_run_queue_lengths</span><span class="p" data-group-id="7091723392-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="7091723392-2">(</span><span class="p" data-group-id="7091723392-2">)</span></code></pre><p>Equivalent to calling
│ │ │  <code class="inline">lists:sum(</code><a href="#statistics_run_queue_lengths"><code class="inline">statistics(run_queue_lengths)</code></a><code class="inline">)</code>,
│ │ │ -but more efficient.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_total_run_queue_lengths_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="0882120457-1">(</span><span class="ss">total_run_queue_lengths_all</span><span class="p" data-group-id="0882120457-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="0882120457-2">(</span><span class="p" data-group-id="0882120457-2">)</span></code></pre><p>Equivalent to calling
│ │ │ +but more efficient.</p><p>Available since OTP 18.3</p></li><li><pre id="statistics_total_run_queue_lengths_all"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="3532873389-1">(</span><span class="ss">total_run_queue_lengths_all</span><span class="p" data-group-id="3532873389-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="3532873389-2">(</span><span class="p" data-group-id="3532873389-2">)</span></code></pre><p>Equivalent to calling
│ │ │  <code class="inline">lists:sum(</code><a href="#statistics_run_queue_lengths_all"><code class="inline">statistics(run_queue_lengths_all)</code></a><code class="inline">)</code>,
│ │ │ -but more efficient.</p><p>Available since OTP 20.0</p></li><li><pre id="statistics_wall_clock"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="2363691234-1">(</span><span class="ss">wall_clock</span><span class="p" data-group-id="2363691234-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="2363691234-2">{</span><span class="n">Total</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="2363691234-3">(</span><span class="p" data-group-id="2363691234-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="2363691234-4">(</span><span class="p" data-group-id="2363691234-4">)</span><span class="p" data-group-id="2363691234-2">}</span></code></pre><p>Returns information about wall clock. <code class="inline">wall_clock</code> can be used in the same
│ │ │ +but more efficient.</p><p>Available since OTP 20.0</p></li><li><pre id="statistics_wall_clock"><code class="makeup erlang" translate="no"><span class="nf">statistics</span><span class="p" data-group-id="7705376790-1">(</span><span class="ss">wall_clock</span><span class="p" data-group-id="7705376790-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p" data-group-id="7705376790-2">{</span><span class="n">Total</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="7705376790-3">(</span><span class="p" data-group-id="7705376790-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">SinceLastCall</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="7705376790-4">(</span><span class="p" data-group-id="7705376790-4">)</span><span class="p" data-group-id="7705376790-2">}</span></code></pre><p>Returns information about wall clock. <code class="inline">wall_clock</code> can be used in the same
│ │ │  manner as <code class="inline">runtime</code>, except that real time is measured as opposed to runtime or
│ │ │  CPU time.</p></li></ul>
│ │ │    </section>
│ │ │  </section>
│ │ │  <section class="detail" id="system_flag/2">
│ │ │  
│ │ │    <div class="detail-header">
│ │ │ @@ -16478,65 +16478,65 @@
│ │ │                       when
│ │ │                           Tracer :: <a href="#t:pid/0">pid</a>() | <a href="#t:port/0">port</a>() | {<a href="#t:module/0">module</a>(), <a href="#t:term/0">term</a>()} | false,
│ │ │                           PrevTracer :: <a href="#t:pid/0">pid</a>() | <a href="#t:port/0">port</a>() | {<a href="#t:module/0">module</a>(), <a href="#t:term/0">term</a>()} | false;
│ │ │                   (reset_seq_trace, true) -> true.</pre>
│ │ │  
│ │ │        </div>
│ │ │  
│ │ │ -<p>Sets a system flag to the given value.</p><p>The possible flags to set are:</p><ul><li><pre><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="1974402869-1">(</span><span class="ss">backtrace_depths</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1974402869-2">(</span><span class="p" data-group-id="1974402869-2">)</span><span class="p" data-group-id="1974402869-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="1974402869-3">(</span><span class="p" data-group-id="1974402869-3">)</span></code></pre><p> Sets the maximum depth of call stack back-traces in the exit reason element of
│ │ │ +<p>Sets a system flag to the given value.</p><p>The possible flags to set are:</p><ul><li><pre><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="0613165479-1">(</span><span class="ss">backtrace_depths</span><span class="p">,</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="0613165479-2">(</span><span class="p" data-group-id="0613165479-2">)</span><span class="p" data-group-id="0613165479-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">non_neg_integer</span><span class="p" data-group-id="0613165479-3">(</span><span class="p" data-group-id="0613165479-3">)</span></code></pre><p> Sets the maximum depth of call stack back-traces in the exit reason element of
│ │ │  <code class="inline">'EXIT'</code> tuples. The flag also limits the stacktrace depth returned by
│ │ │ -<a href="#process_info/2"><code class="inline">process_info/2</code></a> item <a href="#process_info_current_stacktrace"><code class="inline">current_stacktrace</code></a>.</p><p>Returns the old value of the flag.</p></li><li><pre id="system_flag_cpu_topology"><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="1842656371-1">(</span><span class="ss">cpu_topology</span><span class="p">,</span><span class="w"> </span><span class="nf">cpu_topology</span><span class="p" data-group-id="1842656371-2">(</span><span class="p" data-group-id="1842656371-2">)</span><span class="p" data-group-id="1842656371-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">cpu_topology</span><span class="p" data-group-id="1842656371-3">(</span><span class="p" data-group-id="1842656371-3">)</span></code></pre><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p><em>This argument is deprecated.</em> Instead of using this argument, use
│ │ │ +<a href="#process_info/2"><code class="inline">process_info/2</code></a> item <a href="#process_info_current_stacktrace"><code class="inline">current_stacktrace</code></a>.</p><p>Returns the old value of the flag.</p></li><li><pre id="system_flag_cpu_topology"><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="2251069954-1">(</span><span class="ss">cpu_topology</span><span class="p">,</span><span class="w"> </span><span class="nf">cpu_topology</span><span class="p" data-group-id="2251069954-2">(</span><span class="p" data-group-id="2251069954-2">)</span><span class="p" data-group-id="2251069954-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">cpu_topology</span><span class="p" data-group-id="2251069954-3">(</span><span class="p" data-group-id="2251069954-3">)</span></code></pre><section role="note" class="admonition warning"><h4 class="admonition-title warning">Warning</h4><p><em>This argument is deprecated.</em> Instead of using this argument, use
│ │ │  command-line argument <a href="erl_cmd.html#%2Bsct"><code class="inline">+sct</code></a> in <a href="erl_cmd.html">erl</a>.</p><p>When this argument is removed, a final CPU topology to use is determined at
│ │ │  emulator boot time.</p></section><p>Sets the user-defined <code class="inline">CpuTopology</code>. The user-defined CPU topology overrides any
│ │ │  automatically detected CPU topology. By passing <code class="inline">undefined</code> as <code class="inline">CpuTopology</code>,
│ │ │  the system reverts to the CPU topology automatically detected. The returned
│ │ │  value equals the value returned from <code class="inline">erlang:system_info(cpu_topology)</code> before
│ │ │  the change was made.</p><p>Returns the old value of the flag.</p><p>The CPU topology is used when binding schedulers to logical processors. If
│ │ │  schedulers are already bound when the CPU topology is changed, the schedulers
│ │ │  are sent a request to rebind according to the new CPU topology.</p><p>The user-defined CPU topology can also be set by passing command-line argument
│ │ │  <a href="erl_cmd.html#%2Bsct"><code class="inline">+sct</code></a> to <a href="erl_cmd.html">erl</a>.</p><p>For information on type <code class="inline">CpuTopology</code> and more, see
│ │ │  <a href="#system_info_cpu_topology"><code class="inline">erlang:system_info(cpu_topology)</code></a> as
│ │ │  well as command-line flags <a href="erl_cmd.html#%2Bsct"><code class="inline">+sct</code></a> and
│ │ │ -<a href="erl_cmd.html#%2Bsbt"><code class="inline">+sbt</code></a> in <a href="erl_cmd.html">erl</a>.</p></li><li><pre id="system_flag_dirty_cpu_schedulers_online"><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="7821714854-1">(</span><span class="ss">dirty_cpu_schedulers_online</span><span class="p">,</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="7821714854-2">(</span><span class="p" data-group-id="7821714854-2">)</span><span class="p" data-group-id="7821714854-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="7821714854-3">(</span><span class="p" data-group-id="7821714854-3">)</span></code></pre><p>Sets the number of dirty CPU schedulers online. Range is
│ │ │ +<a href="erl_cmd.html#%2Bsbt"><code class="inline">+sbt</code></a> in <a href="erl_cmd.html">erl</a>.</p></li><li><pre id="system_flag_dirty_cpu_schedulers_online"><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="8110078075-1">(</span><span class="ss">dirty_cpu_schedulers_online</span><span class="p">,</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="8110078075-2">(</span><span class="p" data-group-id="8110078075-2">)</span><span class="p" data-group-id="8110078075-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="nf">pos_integer</span><span class="p" data-group-id="8110078075-3">(</span><span class="p" data-group-id="8110078075-3">)</span></code></pre><p>Sets the number of dirty CPU schedulers online. Range is
│ │ │  <code class="inline">1 &lt;= DirtyCPUSchedulersOnline &lt;= N</code>, where <code class="inline">N</code> is the smallest of the return
│ │ │  values of <code class="inline">erlang:system_info(dirty_cpu_schedulers)</code> and
│ │ │  <code class="inline">erlang:system_info(schedulers_online)</code>.</p><p>Returns the old value of the flag.</p><p>The number of dirty CPU schedulers online can change if the number of schedulers
│ │ │  online changes. For example, if 12 schedulers and 6 dirty CPU schedulers are
│ │ │  online, and <a href="#system_flag/2"><code class="inline">system_flag/2</code></a> is used to set the number of
│ │ │  schedulers online to 6, then the number of dirty CPU schedulers online is
│ │ │  automatically decreased by half as well, down to 3. Similarly, the number of
│ │ │  dirty CPU schedulers online increases proportionally to increases in the number
│ │ │  of schedulers online.</p><p>For more information, see
│ │ │  <a href="#system_info_dirty_cpu_schedulers"><code class="inline">erlang:system_info(dirty_cpu_schedulers)</code></a>
│ │ │  and
│ │ │ -<a href="#system_info_dirty_cpu_schedulers_online"><code class="inline">erlang:system_info(dirty_cpu_schedulers_online)</code></a>.</p><p>Available since OTP 17.0</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="5909187763-1">(</span><span class="ss">erts_alloc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="5909187763-2">{</span><span class="n">Alloc</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="5909187763-3">(</span><span class="p" data-group-id="5909187763-3">)</span><span class="p">,</span><span class="w"> </span><span class="n">F</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">atom</span><span class="p" data-group-id="5909187763-4">(</span><span class="p" data-group-id="5909187763-4">)</span><span class="p">,</span><span class="w"> </span><span class="n">V</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><span class="w"> </span><span class="nf">integer</span><span class="p" data-group-id="5909187763-5">(</span><span class="p" data-group-id="5909187763-5">)</span><span class="p" data-group-id="5909187763-2">}</span><span class="p" data-group-id="5909187763-1">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w">
│ │ │ +<a href="#system_info_dirty_cpu_schedulers_online"><code class="inline">erlang:system_info(dirty_cpu_schedulers_online)</code></a>.</p><p>Available since OTP 17.0</p></li><li><pre><code class="makeup erlang" translate="no"><span class="nf">system_flag</span><span class="p" data-group-id="3765060131-1">(</span><span class="ss">erts_alloc</span><span class="p">,</span><span class="w"> </span><span class="p" data-group-id="3765060131-2">{</span><span class="n">Alloc</span><span class="w"> </span><span class="p">:</span><span class="p">:</span><

TRUNCATED DUE TO SIZE LIMIT: 10485760 bytes